Status Reports

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Spirit Mission Manager Reports:
 
Spirit Standing By
Sols 1643-1650

Spirit continues to ride out the Martian winter by doing minimal activities to conserve power. The rover completes very light science observations every three to four Martian days, known as sols, and relays data to NASA's Odyssey orbiter to be transmitted to Earth every four sols. Otherwise, Spirit mostly sleeps. This pattern is not likely to change until sunlight on the rover's solar array consistently generates 250 watt-hours or more (enough energy to light a 100-w

Spirit Standing By
Sols 1643-1650

Spirit continues to ride out the Martian winter by doing minimal activities to conserve power. The rover completes very light science observations every three to four Martian days, known as sols, and relays data to NASA's Odyssey orbiter to be transmitted to Earth every four sols. Otherwise, Spirit mostly sleeps. This pattern is not likely to change until sunlight on the rover's solar array consistently generates 250 watt-hours or more (enough energy to light a 100-watt bulb for 2.5 hours). Barring dust-cleaning winds, that is not expected to happen before about mid-October.

Spirit remains healthy, with all subsystems performing as expected as of the Odyssey downlink to Earth on sol 1646 (Aug. 19, 2008). Solar-array energy has dropped back to 229 watt-hours after recently reaching the high 230's. This drop is the result of an increase in tau -- a measure of atmospheric opacity caused by suspended dust -- from 0.19 to 0.29. Spirit is approaching a time of year when the rover has historically seen increased atmospheric dust levels. Given the rover's low power state, engineers will be watching this trend very closely.

Sol-by-sol summary

During the past week, Spirit completed the following activities:

Sol 1643 (Aug. 16, 2008): Spirit monitored atmospheric darkness caused by dust with the panoramic camera. Spirit acquired column 15, part 2 of the so-called "Bonestell panorama," using all 13 filters of the panoramic camera.

Sol 1644: Spirit recharged the batteries.

Sol 1645: Spirit recharged the batteries.

Sol 1646: Engineers on Earth transmitted a new plan of activities at X-band frequencies directly to Spirit's high-gain antenna. Spirit relayed data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1647: Spirit monitored atmospheric opacity with the navigation camera and acquired column 17, part 2 of the "Bonestell camera," using all 13 color filters of the panoramic camera.

Sol 1648: Spirit recharged the batteries.

Sol 1649: Plans called for Spirit to continue to rest and recharge the batteries.

Sol 1650 (Aug. 24, 2008): Spirit was to receive a new plan of activities transmitted at X-band frequencies directly to Spirit's high-gain antenna. The rover was scheduled to relay data to NASA's Odyssey orbiter for transmission to Earth.

Odometry

As of sol 1642 (Aug. 15, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Spirit Standing By
Sols 1635-1642

Though Spirit is using less energy to run heaters as Martian winter slowly gives way to spring, dust on the rover's solar arrays continues to block sunlight. Presently about one-third -- 34 percent -- of sunlight reaching the arrays is penetrating the layer of dust to generate electricity. This is a primary reason why Spirit's third winter on the red planet has been more difficult than the first two.

Energy has been steady, averaging 235 watt-hours daily (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Tau, a measure of atmospheric dust, and the dust factor, a measure of the amount of dust on the solar arrays, have also been steady at 0.197 and 0.340, respectively. The Tau measurement indicates that 80 to 82 percent of direct sunlight makes it through the atmosphere and reaches the array (the rest is scattered or absorbed, though scattered light also contributes to Spirit's energy).

Currently, Spirit spends one of every four Martian days, or sols, taking science images. The slight energy increase isn't yet sufficient to allow more activity.

Spirit remains healthy and all subsystems are normal as of the latest downlink of information from the Odyssey orbiter on sol 1638 (Aug. 11, 2008).

Sol-by-sol summary

 

In addition to measuring atmospheric dust with the panoramic camera, Spirit completed the following activities:

Sol 1635 (Aug. 8, 2008): Spirit implemented the runout portion of the master sequence of commands already on board the rover, then received new instructions from Earth via the rover's high-gain antenna. The rover recharged the batteries.

Sol 1636: Spirit implemented the runout portion of the master sequence of commands already on board the rover and recharged the batteries.

Sol 1637: Spirit woke up and listened for potential transmissions from Earth at X-band frequencies using the rover's broad-beam, low-gain antenna. Spirit acquired column 13, part 2 of the so-called "Bonestell panorama," using all 13 filters of the panoramic camera.

Sol 1638: Spirit woke up and listened for signals from Earth at X-band frequencies using the low-gain antenna. Spirit completed the runout portion of the master sequence of commands on board the rover and relayed data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1639: Spirit woke up and listened for signals from Earth using the rover's low-gain antenna. Engineers on Earth transmitted a new plan of activities at X-band frequencies to the rover's high-gain antenna. Those plans called for Spirit to spend the day surveying the horizon and monitoring the dune field known as "El Dorado" with the panoramic camera.

Sol 1640: Plans called for Spirit to complete the runout portion of the master sequence of commands on board the rover. Spirit was to wake up and listen for signals from Earth using the low-gain antenna and recharge the batteries. To save energy, Spirit was not directed to measure atmospheric opacity, known as Tau.

Sol 1641: Plans called for Spirit to complete the runout portion of the master sequence of commands on board the rover. Spirit was to wake up and listen for signals from Earth using the low-gain antenna and recharge the batteries. Spirit was not scheduled to measure atmospheric opacity.

Sol 1642 (Aug. 15, 2008): Plans called for Spirit to wake up and listen for signals from Earth using the low-gain antenna. Later, the rover was to relay information to Odyssey about the past four sols of activity.

Odometry

As of sol 1638 (Aug. 11, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Waiting Out the Winter
Sols 1628-1634

Spirit's battery levels are slowly edging upward, thanks to a slight decrease in atmospheric dust (Tau) and a gradual increase in sunlight as winter gives way to spring.

Early in the week, Spirit spent two Martian days carrying out contingency plans following a temporary delay in data transmission from Earth. Spirit implemented the so-called "runout" portion of an earlier master sequence on sols 1628 and 1629 (Aug. 1-2, 2008). Subsequent relays of new instructions from Earth on sols 1629 and 1632 (Aug. 2 and Aug. 5, 2008) went off without a hitch.

Spirit remains healthy, with all subsystems performing as expected as of sol 1630 (Aug. 3, 2008).

 

Sol-by-sol summary

In addition to using the panoramic camera to make daily measurements of dust-related changes in atmospheric clarity, Spirit completed the following activities:

Sol 1628 (Aug. 1, 2008): Spirit implemented the runout portion of the master sequence of commands already on board the rover.

Sol 1629: Upon awakening, Spirit continued to implement the runout portion of the master sequence sent earlier. Spirit then received new instructions directly from Earth via the rover's high-gain antenna.

Sol 1630: Spirit acquired column 13 of the "Bonestell panorama" using all 13 color filters of the panoramic camera. The rover relayed fresh data from Mars at UHF radio frequencies to NASA's Odyssey orbiter to be transmitted to Earth.

Sol 1631: Spirit recharged the batteries.

Sol 1632: Spirit received new instructions from Earth via the rover's high-gain antenna.

Sol 1633: Spirit acquired six freeze frames for a time-lapse movie in search of Martian clouds using the navigation camera. The rover took spot images of the sky for calibration purposes with the panoramic camera and monitored dust on the panoramic-camera mast assembly.

Sol 1634 (Aug. 7, 2008): Spirit transmitted fresh data to Odyssey to be relayed to Earth.

 

Odometry

As of sol 1634 (Aug. 7, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Time to Recharge the Batteries
Sols 1621-1627

With Batteries Charged, Spirit is Ready for More Science

Spirit has fully recovered from a recent rundown in battery power. Energy has improved to levels not seen since sol (Martian day) 1604 (July 7, 2008). The hit in battery energy was primarily the result of data transmissions taking place later in the day, when less solar energy was available.

During the past week, rover planners eliminated the late communications sessions. Spirit is not scheduled to have another one until sol 1636 (Aug. 9, 2008). To mitigate the impact that one will have on power, rover planners plan to shorten the duration of data transmission from 20 minutes to only 10 minutes. This will allow sufficient time to get new instructions on board the rover while minimizing battery drain.

A transmitter problem thwarted data transmission on sol 1625 (July 29, 2008). The uplink from Earth was to have loaded activity plans and maintenance instructions for sols 1626, 1627, 1628 and 1629 (July 30-Aug. 2, 2008). The sequences already on board Spirit were designed with built-in contingency plans to handle just such an event. As a result, while Spirit continues the "runout" portion of the earlier master sequence, rover operators will send a new set of commands for sols 1630, 1631 and 1632 (Aug. 3-5, 2008) on sol 1629 (Aug. 2, 2008).

Spirit remains healthy, with all subsystems performing as expected as of sol 1626.

Sol-by-sol summary

In addition to using the panoramic camera to make daily measurements of dust-related changes in visibility, Spirit completed the following activities:

Sol 1621 (July 25, 2008): Spirit recharged the batteries.

Sol 1622: Spirit received instructions from Earth via the rover's high-gain antenna and relayed data to NASA's Odyssey orbiter via the rover's UHF antenna.

Sol 1623: Spirit acquired images of sand formations with the rear hazard-avoidance and navigation cameras. The rover took six, time-lapse, movie frames in search of clouds with the navigation camera, as well as images of the sky (called "sky flats") for calibration purposes.

Sol 1624: Spirit recharged the batteries.

Sol 1625: Spirit took spot images of the sky for calibration purposes with the panoramic camera and acquired movie frames in search of clouds with the navigation camera.

Sol 1626: Spirit completed a horizon survey with the panoramic camera and relayed data to Odyssey for transmission to Earth.

Sol 1627 (July 31, 2008): Spirit recharged the batteries.

Odometry

As of sol 1626 (July 30, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Time to Recharge the Batteries
Sols 1615-1620

Time to Recharge the Batteries

Spirit is recovering from a recent rundown in battery power. Over the last two weeks, Spirit's battery levels have steadily dropped by about 18 percent. The decrease appears to be a result of transmitting data to Earth later in the day and staying awake longer to accommodate extra science activities.

When Spirit sends transmissions late in the day, there's not enough sunlight left to recharge the batteries. As a consequence, each late uplink has contributed to an energy deficit.

Barring sudden changes in Martian temperature or atmospheric dust levels, engineers expect it may take as long as two weeks to recharge the batteries enough to resume work on the Bonestell panorama and other science activities.

Spirit remains healthy and all subsystems are operating as expected as of Martian day, or sol, 1618 (July 22, 2008).

Sol-by-sol summary

In addition to daily, panoramic-camera measurements of atmospheric opacity caused by dust, Spirit completed the following activities:

Sol 1615 (July 19, 2008): Spirit received new instructions from Earth via the rover's high-gain antenna.

Sol 1616: Spirit monitored dust accumulation on the panoramic-camera mast assembly.

Sol 1617: Spirit recharged the batteries.

Sol 1618: Spirit received instructions from Earth over the rover's high-gain antenna and relayed data to Earth via NASA's Mars Odyssey orbiter.

Sol 1619: Spirit took spot images of the sky for calibration purposes with the panoramic camera and acquired movie frames in search of clouds with the navigation camera.

Sol 1620 (July 24, 2008): Spirit recharged the batteries.

Odometry

As of sol 1618 (July 22, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





A Juggling Act
Sols 1608-1614

Winter planning for Spirit requires human operators to perform a complex juggling act to maintain overall rover health. They must manage engineering activities, such as receiving science and engineering data from Mars and sending new operation plans from Earth, as well as try to fit in science observations when possible. But they must also give the rover sufficient downtime between these activities to recharge the batteries. In recent months, the team's juggling skills have continued to improve.

Meanwhile, Mars has been helping out with steady temperatures and low levels of atmospheric dust, providing stability when it comes to allocating energy for heating and predicting the amount of sunlight reaching the rover's solar panels to generate electricity. Solar energy has been steady between 225 watt-hours to 230 watt-hours, of which about 65 to 75 watt-hours is required for heating the batteries and the miniature thermal emission spectrometer.

The overall state of charge on the battery has dropped slightly as a result of the timing of engineering and science activities. To restore the state of charge, the rover team will be making adjustments in upcoming plans.

Spirit is healthy and all subsystems are performing as expected as of sol 1610 (July 13, 2008).

Sol-by-sol summary

During the past week, in addition to making daily measurements of atmospheric opacity caused by dust with the panoramic camera, Spirit completed the following activities:

Sol 1608 (July 11, 2008): Spirit received new instructions from Earth via the rover's high-gain antenna.

Sol 1609: Spirit acquired column 17, part 3 of the so-called "Bonestell panorama" using all 13 color filters of the panoramic camera. The rover acquired six, time-lapse, movie frames in search of clouds with the navigation camera.

Sol 1610: Spirit relayed science and engineering data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1611: Spirit received instructions from Earth over the rover's high-gain antenna and sent a timing beep to Earth at X-band frequencies.

Sol 1612: Spirit acquired column 15, part 3 of the full-color Bonestell panorama.

Sol 1613: Spirit recharged the battery.

Sol 1614 (July 18, 2008): Spirit relayed science and engineering data to Odyssey for transmission to Earth.

Odometry

As of sol 1610 (July 13, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Solar Energy Evens Out
Sols 1601-1607

A week after the winter solstice, NASA's Mars rover Spirit is experiencing stable solar energy levels of between 225 watt-hours and 230 watt-hours. (One hundred watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Spirit continues to perform light science activities every three to four Martian days, or sols. Science activities this week included acquiring additional frames of the so-called "Bonestell panorama" of Spirit's overwintering locale.

The rover continues to relay data to NASA's Odyssey orbiter every four sols. The reduced level of activity has allowed Spirit to maintain a healthy battery charge despite the low level of solar energy input.

Spirit is healthy and all subsystems were performing as expected as of the downlink of fresh data from Odyssey on Sol 1606 (July 9, 2008).

Sol-by-sol summary

During the past week, Spirit completed the following activities:

Sol 1601 (July 4, 2008): Spirit assessed atmospheric dust levels based on the darkness of the sky with the panoramic camera.

Sol 1602: Spirit assessed atmospheric dust, monitored the dune field known as "El Dorado," and took spot images of the sky for calibration purposes with the panoramic camera. The rover relayed data to Odyssey for transmission to Earth.

Sol 1603: Spirit recharged the battery and measured atmospheric dust opacity with the panoramic camera.

Sol 1604: Spirit received a new activity plan from Earth via the rover's high-gain antenna and assessed atmospheric dust levels with the panoramic camera.

Sol 1605: Spirit again gauged atmospheric dust levels and also surveyed the horizon with the panoramic camera. The rover acquired Column 16, Part 4 of the Bonestell panorama, using all 13 color filters of the panoramic camera.

Sol 1606: Spirit assessed atmospheric dust with the panoramic camera and sent fresh data to Odyssey for transmision to Earth.

Sol 1607 (July 10, 2008): Spirit recharged the battery and measured atmospheric dust with the panoramic camera.

Odometry

As of sol 1606 (July 9, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).





Biding Time

Sols 1594-1600, posted July 8, 2008

Spirit continues to ride out the Martian winter by doing minimal activities to conserve power. The rover conducts very light science activities every three to four Martian days, or sols, and relays data to NASA's Odyssey orbiter for transmission to Earth every 4 sols. The rest of the time, Spirit mostly sleeps.

As it has been some time since Spirit's operators were able to synchronize the spacecraft clock to Earth time, they wished to determine how far the spacecraft clock had drifted (how much it had changed over time). Synchronization of the clock is a process that requires a power-intensive, two-way, X-band communications link. When the power situation allowed it, they decided to perform an X-band "beep" (a five-minute, low-gain communication session) to estimate the amount of drift. The transmission of plans to do so on sol 1594 (June 27, 2008) were not detected by the ground station. Engineers hoped to make another attempt on sol 1604 (July 7, 2008).

Spirit is healthy and all subsystems were performing as expected as of the Odyssey downlink on sol 1598 (July 1, 2008). Solar-array energy has been steady within the range of 225 watt-hours to 230 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Sol-by-sol summary

During the past week, Spirit completed the following activities:

Sol 1594 (June 27, 2008): Plans called for Spirit to perform a five-minute "beep" at X-band frequencies after relaying data to Earth via the Odyssey orbiter.

Sol 1595: Spirit recharged the battery and measured atmospheric dust opacity, known as Tau, using the panoramic camera.

Sol 1596: Spirit recharged the battery and measured atmospheric dust opacity with the panoramic camera.

Sol 1597: Spirit recharged the battery and measured atmospheric dust opacity with the panoramic camera.

Sol 1598: Spirit received new instructions from Earth via the rover's high-gain, X-band antenna and relayed data to Odyssey at UHF frequencies for transmission of the latest Martian data to Earth. The rover measured atmospheric darkness caused by suspended dust particles with the panoramic camera.

Sol 1599: Spirit conducted light remote sensing.

Sol 1600 (July 3, 2008): Spirit recharged the battery and again measured atmospheric dust with the panoramic camera.

Odometry

As of sol 1598 (July 1, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).


Here Comes the Sun

Sols 1587-1593, posted July 8, 2008

With this week's passage of the longest night and shortest day of the year, also known as the winter solstice, Spirit's solar power levels should slowly but steadily increase. The winter solstice occurred on Martian day, or sol, 1591 (June 24, 2008, Pacific time).

In fact, Spirit's solar array energy and battery state of charge have already improved in recent days to the point where rover operators have begun adding some planning features back into the rover's schedule. The first change, adopted as of sol 1592 (June 25, 2008), was to return to a planning schedule covering every 3 or 4 sols. The plans themselves remain quite spartan at this time. In particular, rover operators are still planning to have Spirit relay data to Earth only every 4 sols. To do this, the rover sends data to NASA's Odyssey spacecraft, in orbit above Mars. To save power, engineers are keeping the data relays short in duration. Spirit has begun measuring dust-related atmospheric darkness every sol instead of every other sol.

Because it has been some time since engineers have been able to synchronize the spacecraft clock to Earth time, they decided to determine how much the clock had "drifted" -- that is, changed with time. To do this usually requires a power-intensive, two-way, X-Band communication session. This time, to save energy, they decided to perform an X-band "beep," a five-minute communication session using the rover's low-gain antenna, on sol 1594 (June 27, 2008). Accuracy will not be as good, but they expect to get an estimate of drift that is accurate to within about a minute.

Spirit is healthy and all subsystems are performing as expected as of the Odyssey downlink on sol 1590 (June 23, 2008). Solar array energy has been steady at 230 watt-hours, enough energy to light a 100-watt bulb for 2.5 hours.

Sol-by-sol summary

During the past week, Spirit completed the following activities:

Sol 1587 (June 20, 2008): Spirit recharged the battery.

Sol 1588: Spirit recharged the battery and received new instructions direct from Earth via the rover's high-gain dish antenna. Spirit measured atmospheric dust opacity, known as Tau, with the panoramic camera.

Sol 1589: Spirit recharged the battery.

Sol 1590: Spirit recharged the battery, measured atmospheric opacity caused by dust with the panoramic camera, and relayed data to Odyssey for transmission to Earth.

Sol 1591: Spirit recharged the battery and received a backup relay of commands from Earth via the rover's high-gain antenna.

Sol 1592: Spirit recharged the battery and conducted light remote sensing.

Sol 1593: Spirit recharged the battery.

Sol 1594 (June 27, 2008): Plans called for Spirit to send data to Odyssey for relay to Earth and transmit a five-minute signal to Earth to allow spacecraft operators to estimate drift in the spacecraft clock.

Odometry

As of sol 1586 (June 19, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).


Battery Power on the Rise

Sols 1580-1586, posted July 8, 2008

Spirit's battery is recharging nicely now that rover planners have reduced the frequency of communications to and from the rover during the darkest days of Martian winter. Most measures of battery health are showing an increase of about 2 amp-hours in the battery state of charge (an amp-hour is equivalent to the amount of charge flowing for one hour from a current of 1 amp). The minimum state of charge has improved from 10.92 amp-hours to 12.97 amp-hours, the maximum from 16.77 amp-hours to 18.17 amp-hours, which is fairly close to the battery's full capacity of 19.5 amp-hours.

Because battery energy increased sufficiently, the team added 12 minutes of remote sensing science to Spirit's to-do list for Sol 1586 (June 19, 2008). Spirit was to monitor atmospheric dust with the panoramic camera as well as dust on the panoramic-camera mast assembly and acquire seven, time-lapse movie frames in search of clouds with the navigation camera. Engineers anticipate that the additional activities will have no significant effect on the battery's state of charge.

Skies remain remarkably clear. Solar array energy is up slightly, averaging 229 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Atmospheric darkness caused by dust (known as Tau) increased by an insignificant amount, going from an average of 0.193 the previous week to 0.205 this week. The dust factor, the fraction of sunlight hitting the arrays that penetrates the dust layer, also rose insignificantly, from 0.349 to 0.352.

Rover planners are generating new activity plans for Spirit only once a week to minimize uplink time and therefore the length of time the rover must stay awake. Spirit relays data to Earth only every fourth sol to minimize battery usage.

In addition to estimating the amount of scattering and absorption of sunlight by atmospheric dust, Spirit received one transmission of new instructions direct from Earth to the rover's high-gain antenna on Sol 1581 (June 14, 2008). Spirit sent two transmissions of data to Earth via Odyssey on sols 1582 and 1586 (June 15 and June 19, 2008). Data from the sol 1582 downlink showed that the backup uplink on sol 1584 (June 17, 2008) was not needed and the communications link was shortened to save energy.

Spirit remains healthy and all subsystems were performing as expected as of the downlink to Earth via NASA's Odyssey Mars orbiter on sol (Martian day) 1582 (June 15, 2008).

Sol-by-sol summary

During the past week, Spirit completed the following activities:

Sol 1580 (June 13, 2008): Spirit recharged the battery and measured atmospheric opacity caused by dust (Tau) using the panoramic camera.

Sol 1581: Spirit recharged the battery and received new instructions direct from Earth to the rover's high-gain dish antenna.

Sol 1582: Spirit soaked up the sunlight to recharge the battery, assessed atmospheric darkness caused by dust particles with the panoramic camera, and sent data to NASA's Odyssey orbiter for transmission to Earth.

Sol 1583: Spirit recharged the battery.

Sol 1584: Spirit recharged the battery, surveyed atmospheric dust with the panoramic camera, and received new commands from Earth over the rover's high-gain antenna.

Sol 1585: Spirit recharged the battery.

Sol 1586 (June 19, 2008): Plans called for Spirit to recharge the battery, conducted remote sensing, and send data to Odyssey for relay to Earth.

Odometry

As of sol 1578 (June 11, 2008), Spirit’s total odometry remained at 7,528.0 meters (4.7 miles).


Visit the rover site for all status reports. Spirit Still "Sitting Pretty" for This Time of Year

Sols 1517-1524, April 21, 2008

Despite a slight increase in atmospheric opacity caused by dust, Spirit is still enjoying higher-than-expected energy levels for this time of year. Solar array input has been approximately 240 watt-hours per Martian day, or sol (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

Clear skies have had the unfavorable effect, however, of causing a drop in temperatures at the surface of Mars, increasing the bitter cold experienced by Spirit's rover electronics module. Nighttime temperatures are creeping closer to the point where they will trigger the survival heaters, which draw a large amount of power. A much more desirable strategy is to keep Spirit awake long enough each day to keep the electronics module sufficiently warm with heat from normal operations, providing more time for science observations. "Awake time" vs. heating time is just one of the many trade-offs the team makes each day to keep Spirit going through the Martian winter.

Sol-by-sol summary

In addition to daily communications that include direct-from-Earth instructions via the rover's high-gain antenna and, as power permits, data relays to Earth via the Odyssey orbiter, Spirit continues to monitor atmospheric dust levels each day with the panoramic camera. In addition, during the past week, Spirit completed the following activities:

Sol 1517 (April 9, 2008): Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; acquired column 8, part 3 of the full-color "Bonestell Panorama" using all 13 filters of the panoramic camera; and shot movie frames in search of clouds with the navigation camera.

Sol 1518: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; acquired a 2-by-1-by-1 stack of microscopic images of the rover's solar array; acquired column 9, part 1 of the Bonestell panorama; and took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1519: Spirit surveyed the rover's external calibration target with the miniature thermal emission spectrometer and acquired column 9, part 2 of the Bonestell panorama. To conserve energy, the rover did not relay data to Odyssey.

Sol 1520: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; measured atmospheric opacity caused by dust with the navigation camera (as well as the panoramic camera); and acquired movie frames in search of clouds with the navigation camera. The rover took spot images of the sky and surveyed the horizon with the panoramic camera. Spirit did not relay data to Odyssey.

Sol 1521: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; calibrated the elevation of the miniature thermal emission spectrometer; and acquired column 9, part 3 of the Bonestell panorama.

Sol 1522: Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer; took thumbnail images of the sky and surveyed the horizon with the panoramic camera; and acquired lossless-compression images of wind-blown deposits next to the rover with the hazard-avoidance cameras. Spirit did not relay data to Odyssesy.

Sol 1523: Spirit recharged the battery and did not relay data to Odyssey.

Sol 1524: (April 16, 2008): Spirit recharged the battery.

Odometry

As of sol 1524 (April 16, 2008), Spirit’s total odometry remained at 7,528.07 meters (4.68 miles).


Clear Skies at "Home Plate"

Sols 1511-1516

Spirit is currently experiencing the clearest skies seen by either of NASA's two Mars Exploration Rovers. On sol 1511 (April 3, 2008), Tau measurements of atmospheric dust hit an all-time low of 0.127. By sol 1516 (April 8, 2008), this measurement had increased slightly to 0.170. The low Tau values have held power levels at around 250 watt-hours (enough energy to light a 100-watt bulb for about 2.5 hours). If Tau were not so cooperative, Spirit would be getting only about 200 watt-hours of energy, compelling the rover's handlers to disable the heaters on the miniature thermal emission spectrometer and take other measures to conserve power.

The engineering team still expects to implement energy-conservation strategies, but not for several weeks. Meanwhile, Spirit continues to make progress on remote-sensing activities, scientific investigations, and the "Bonestell panorama" of the rover's view from the north rim of "Home Plate."

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera and survey the sky and ground with the miniature thermal emission spectrometer. In addition, during the past week, Spirit completed the following activities:

Sol 1511 (April 3, 2008): Spirit took thumbnail images of the sky with the panoramic camera.

Sol 1512: Spirit gathered compositional data from the soil target known as "Arthur C. Harmon" using the alpha-particle X-ray spectrometer. The rover used the panoramic camera to acquire super-resolution images of a target informally named "Arthur C. Clarke."

Sol 1513: Spirit acquired column 7, part 3 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera.

Sol 1514: Spirit pointed the alpha-particle X-ray spectrometer skyward to measure argon gas in the Martian atmosphere and acquired stability images of the rover's 30-degree tilt. The rover transmitted data to Odyssey and spent about 4.5 hours measuring atmospheric argon. Spirit also acquired column 8, part 1 of the Bonestell panorama and took spot images of the sky for calibration purposes with the panoramic camera.

Sol 1515: Spirit surveyed the sky with the panoramic camera and monitored dust on the panoramic camera mast assembly.

Sol 1516: (April 8, 2008): Spirit acquired column 8, part 2 of the Bonestell panorama and surveyed the horizon with the panoramic camera.

Odometry

As of sol 1516 (April 8, 2008), Spirit’s total odometry remained at 7,528.07 meters (almost 4.68 miles).


Spirit Sees Clearest Skies Since Landing on Mars!

Sols 1498-1503

Like a calm after the recent Martian dust storms, atmospheric dust above Spirit's overwintering site has reached the lowest levels the rover has seen since arriving on Mars. To be sure, sunblocking dust that has settled on the rover's solar panels and low-angle winter sunlight have combined to reduce Spirit's energy levels. But clear skies mean more sunlight penetrates the atmosphere, making rover planners optimistic that Spirit will have a slim but adequate amount of energy to survive until Martian spring.

Earlier estimates predicted a near-starvation energy diet for Spirit during the darkest days of winter. The coming winter solstice, the peak of Martian winter, will be June 25, 2008. To conserve energy, Spirit may have to disable some heaters and curtail communications and other activities, but is expected to be able to conduct limited scientific investigations.

Solar-array energy during the past week has varied between 244 watt-hours and 254 watt-hours, averaging 249.5 watt-hours for the period (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Tau, the measure of atmospheric dust, has averaged 0.2, varying by only a few hundredths. The dust factor has been nearly constant at 0.36 (meaning 36 percent of the sunlight reaching the arrays penetrates the dust layer to make electricity). A low Tau is good; a low dust factor is bad.

Because dust is constantly settling out from the Martian atmosphere onto the solar arrays, Tau and the change in the dust factor are related. When Tau is high, the dust factor rapidly decreases as dust from the atmosphere rains onto the arrays. When Tau is low (as it is now), the atmosphere carries less dust and the dust factor decreases more slowly. The clearer atmosphere doesn't affect dust already on the solar arrays, but it does affect the rate at which new dust is added.

The atmosphere above the Spirit site is remarkably clear at present and Tau has been as low as 0.170 -- the lowest seen by Spirit in the entire mission. Not surprisingly, the dust factor has been virtually unchanged.

Spirit also analyzed material on the external capture magnet. Spirit has several magnets of which two, the capture and filter magnets, are mounted at the front of the solar array. The capture magnet is relatively strong, the filter magnet only half as strong.

Viking data from the 1970s showed that Martian dust was slightly magnetic, comprising 1 to 7 percent magnetic material. Spirit's filter and capture magnets winnow the dust for this material. The capture magnet, being stronger, gathers all magnetic materials while the filter magnet retains only the most magnetic particles. Using the alpha-particle X-ray spectrometer, Spirit can determine the chemical composition of the captured particles. The observations will help scientists ascertain whether the magnetic material is uniform or has more than one constituent. The dust composition provides insight into whether the magnetic material is the product of weathering in the presence of water or weathering of dry bedrock.

Spirit continued to scale back the frequency of afternoon communications with the Odyssey orbiter to save energy. Overhead passes by Odyssey happen late in the day when little solar energy is available, requiring the use of significant battery power. By deleting some of the passes, Spirit can conserve energy acquired earlier in the day to provide power for subsequent science observations. The downside is that fewer passes slow the rate at which pictures and other data can be downlinked to Earth.

Spirit continued work on the Bonestell (Bon-ES-tell) panorama, a high-resolution, 360-degree mosaic of images divided into wedges (columns) spanning roughly 5 compass degrees and extending from near the rover to just above the horizon. Each column typically has three or four separate images or "parts." The panorama is named for Chesley Bonestell (1888-1986), considered the "father of modern space art."

Spirit is healthy and all subsystems are performing as expected.

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera, check for drift (changes with time) in the miniature thermal emission spectrometer, and survey the sky and ground with the instrument. In addition, during the past week, Spirit completed the following activities:

Sol 1498 (March 20, 2008): Spirit placed the alpha-particle X-ray spectrometer on the capture magnet, took images with the hazard avoidance cameras, took images with the navigation camera for lossless-compression visual odometry, and relayed data to Odyssey.

Sol 1499: Spirit acquired column 4, part 2 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera.

Sol 1500: Spirit acquired column 4, part 3 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera.

Sol 1501: Spirit acquired column 5, part 1 of the full-color Bonestell panorama and relayed data to Odyssey during the orbiter's afternoon pass.

Sol 1502: Spirit took six movie frames in search of clouds with the navigation camera and acquired column 5, part 2 of the Bonestell panorama. Using the alpha-particle X-ray spectrometer, Spirit acquired data on the elemental composition of magnetic particles on the external capture magnet.

Sol 1503 (March 26, 2008): Spirit acquired column 5, part 3 of the Bonestell panorama and relayed data to Odyssey. Plans for the following morning called for Spirit to acquire super-resolution images of a rock target informally named "Roger_Zelazny" (after the science fiction author) with the panoramic camera.

Odometry

As of sol 1501 (March 23, 2008), Spirit’s total odometry was 7,528.07 meters (4.68 miles).


Spirit Advances Toward Midwinter

Sols 1504-1510, April 9, 2008

Seasons are about twice as long on Mars as on Earth and are offset relative to Earth because Mars takes about twice as long to complete one orbit around the Sun. At Spirit's location, the fall equinox -- the start of fall, when night and day are equal in length -- arrived Dec. 12, 2007. The winter solstice -- the time of year with the shortest day -- will arrive June 25, 2008.

Solar array energy has varied from 244 watt-hours to 256 watt-hours, averaging 250.4 watt-hours for this period (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Tau, the measure of atmospheric dust, has averaged 0.16, varying by only a hundredth. The dust factor has been nearly constant at 0.35, meaning 35 percent of the sunlight reaching the arrays penetrates the dust layer to make electricity. A low Tau is good because it means the skies are fairly clear; a low dust factor is bad because it means the solar arrays are coated with a fair amount of dust.

Astronomers use the symbol L(s) -- pronounced L-sub-s -- to denote how far Mars has progressed in its orbit around the Sun. If you imagine looking down at the solar system, with the Sun in the middle and Mars orbiting around it, L(s) gives the location of Mars. By definition, L(s) = 0 degrees when the Sun crosses the Martian equator. This is the first day of Martian spring, the vernal equinox, when night and day are equal in length, in the northern hemisphere. It's also the first day of fall, the autumnal equinox, in the southern hemisphere. At Spirit's location in Mars' southern hemisphere, the season is currently mid- to late fall, and L(s) is about 55 degrees, roughly equivalent to Nov. 17 in Earth's northern hemisphere and May 18 in Earth's southern hemisphere. L(s) will equal 90 degrees at the time of the winter solstice.

Spirit is healthy and all subsystems are performing as expected.

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera, check for drift (changes with time) in the miniature thermal emission spectrometer, and survey the sky and ground with the instrument. In addition, during the past week, Spirit completed the following activities:

Sol 1504 (March 27, 2008): Spirit calibrated the miniature thermal emission spectrometer and acquired a microscopic image of the capture magnet.

Sol 1505: Upon awakening, Spirit took spot images of the sky for calibration purposes with the panoramic camera and acquired column 6, part 1 of the full-color "Bonestell panorama" using all 13 filters of the panoramic camera. The rover also recharged the battery.

Sol 1506: Spirit acquired column 6, part 2 of the Bonestell panorama and monitored dust on the panoramic-camera mast assembly. Spirit looked at the miniature thermal emission spectrometer for calibration purposes, acquired microscopic images of the solar panel, and acquired images of the external magnets, which capture magnetic dust particles, using the panoramic camera.

Sol 1507: Spirit acquired column 6, part 3 of the full-color Bonestell panorama and recharged the battery.

Sol 1508: Spirit acquired column 7, part 1 of the full-color Bonestell panorama and relayed data to Odyssey during the orbiter's afternoon pass overhead.

Sol 1509: Spirit surveyed the sky at high Sun with the panoramic camera and completed a "runout" of previously loaded activities after not being able to receive new instructions from Earth. The rover recharged the battery and relayed data to Odyssey.

Sol 1510: (April 2, 2008): Spirit acquired a 1-by-1-by-3 stack of microscopic images of a soil target known informally as "Arthur_C_Hammon" and placed the alpha-particle X-ray spectrometer on the soil target. Plans for the following morning called for Spirit to acquire column 7, part 2 of the full-color Bonestell panorama.

Odometry

As of sol 1509 (April 1, 2008), Spirit’s total odometry was 7,528 meters (almost 4.7 miles).


Spirit Phones Home to Set Clock

Sols 1491-1497, April 2, 2008

Spirit is feeling the strain of juggling activities on Mars in the face of declining power levels as the winter Sun sinks lower on the horizon. After acquiring compositional data from a rock target informally named "Wendell Pruitt," Spirit had to wait a few sols (Martian days) to have enough energy to conduct atmospheric studies and move the robotic arm out of the way for a panoramic-camera portrait of a rock target known as "Freeman." First, the rover had to make a "phone call" to Earth to correct for drift -- changes in time -- in the spacecraft clock.

When Spirit phones home using a direct-to-Earth, X-band communications link, the rover's transmitter has to be running, which requires a fair amount of energy. During more typical, direct-from-Earth communications, only the rover's receiver has to be on. To set the spacecraft clock, Spirit transmits a data product called a time packet. The time packet is used to synchronize the rover's clock back to Earth time (also known as Universal Time). A previous attempt to relay the time packet was unsuccessful, causing Spirit's clock to be off by as much as a minute and a half.

In addition to resetting the clock, Spirit completed a light schedule of activities on sols 1493-1494 (March 15-16, 2008). By sol 1496 (March 18, 2008), Spirit had generated enough solar power to proceed with measurements of argon gas in the Martian atmosphere and studies of the Freeman rock target. Interspersed with those activities, Spirit continued to work on the "Bonestell panorama" and take panoramic-camera images of a target dubbed "C.S. Lewis." The rover spent sols 1492, 1494, and 1497 (March 14, 16, and 19, 2008) recharging the battery, conducting only minimal science activities, and storing data for later transmission to Earth.

Spirit continued to have difficulty receiving spacecraft commands via the rover's high-gain, X-band, dish antenna as a result of the mast that holds the panoramic and navigation cameras getting in the way and partially obscuring the signal. To help address this challenge, rover planners had Spirit complete a self-assessment to see if the rover could independently recognize an occlusion of the high-gain signal and respond by swiveling the high-gain antenna to a different position. The self-assessment, on sol 1493 (March 15, 2008), was successful. Spirit used the technique prior to an actual uplink session on sol 1496 (March 18, 2008), when the rover's handlers were expecting a particularly severe occlusion. The activity was successful and the uplink did not appear to be impeded in any way. Currently, this activity involves having the rover use a temporary parameter that then goes away when the rover shuts down for a nap. Rover planners are considering making the temporary parameter permanent.

Looking forward, Spirit will go increasingly into "hibernate" mode as the Sun continues to dim. Rover planners predict Spirit will be able to conduct science activities until about late April.

Spirit is healthy and all subsystems are performing as expected. The latest available power readings from sol 1496 (March 18, 2008) showed power at 249 watt-hours (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Spirit has no plans to move before the next Martian spring and is hard at work accomplishing as much as possible before power levels drop to a point that temporarily precludes use of the scientific instruments on the rover's arm.

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera, check for drift (changes with time) in the miniature thermal emission spectrometer, and survey the sky and ground with the instrument. In addition, during the past week, Spirit completed the following activities:

Sol 1491 (March 13, 2008): After communicating with Odyssey, Spirit studied the elemental composition of "Wendell Pruitt" with the alpha-particle X-ray spectrometer.

Sol 1492: In addition to monitoring atmospheric dust and conducting surveys with the miniature thermal emission spectrometer, Spirit recharged the battery.

Sol 1493: Spirit initiated a direct-to-Earth communications link using the X-band antenna and transmitted a data packet to correct the spacecraft clock.

Sol 1494: In addition to monitoring atmospheric dust and conducting surveys with the miniature thermal emission spectrometer, Spirit recharged the battery.

Sol 1495: In the morning, Spirit acquired column 3, part 1 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera. Spirit positioned the alpha-particle X-ray spectrometer to measure argon gas in the Martian atmosphere. The rover took a single-frame image with the navigation camera. After communicating with Odyssey, Spirit measured argon with the alpha-particle X-ray spectrometer.

Sol 1496: Spirit monitored dust accumulation on the rover mast and acquired column 3, part 3 of the full-color Bonestell panorama. The rover acquired full-color images, using all 13 filters of the panoramic camera, of the Freeman rock target.

Sol 1497 (March 19, 2008): Spirit looked for changes in the "El Dorado" dune field with the panoramic camera and acquired column 4, part 1 of the Bonestell panorama. The rover recharged the battery. The following morning, Spirit was to acquire movie frames in search of clouds with the navigation camera, acquire super-resolution, panoramic-camera images of a target dubbed "C.S. Lewis half," and survey the horizon with the panoramic camera.

Odometry

As of sol 1496 (March 18, 2008), Spirit’s total odometry was 7,528 meters (almost 4.7 miles).




Work Continues on 360-Degree View of Spirit's Winter Perch

Sols 1478-1483, April 2, 2008

Spirit continued work on the "Bonestell panorama," a full-color, 360-degree view of the rover's surroundings from its overwintering perch on the north-facing edge of "Home Plate." Spirit acquired images for the panoramic mosaic on sols 1478, 1479, 1480 and 1483 (Feb. 29, March 1-2, and March 5, 2008). By the time the final product is ready, the rover will have completed an estimated 60 separate pointings of the panoramic camera in all different directions. Rover planners have nicknamed the panorama in honor of Chesley Bonestell (1888-1986), considered the father of modern space art.

Spirit has also been engaged in efforts to brush away dust from a rock target known as "Wendell Pruitt." The rover used the rock abrasion tool to brush the surface on sol 1479 (March 1, 2008), but the brushing cleared only about half the expected area. On the basis of the results, the rover's handlers adjusted the command sequence to have Spirit perform a "grind scan" to locate the surface of Wendell Pruitt on sol 1482 (March 4, 2008). The goal of this maneuver was to get the rock abrasion tool in place for another attempted brushing, scheduled for sol 1484 (March 6, 2008).

Spirit is healthy and all subsystems are performing as expected.

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera, check for drift (changes over time) in the miniature thermal emission spectrometer, and survey the sky and ground with the instrument. In addition, during the past week, Spirit completed the following activities:

Sol-by-sol summary

To conserve energy, mission planners have restricted the number of sols on which Spirit receives direct-from-Earth instructions via the rover's high-gain antenna and transmits data to Earth via the Odyssey orbiter. Spirit continues, on a daily basis, to monitor atmospheric dust levels with the panoramic camera, check for drift (changes over time) in the miniature thermal emission spectrometer, and survey the sky and ground with the instrument. In addition, during the past week, Spirit completed the following activities:

Sol 1478 (Feb. 29, 2008): Spirit acquired column 1, part 2 of the full-color, panoramic camera images, using all 13 filters of the camera, that will make up the Bonestell panorama. Spirit also recharged the batteries.

Sol 1479: Using the wire brush on the rock abrasion tool, Spirit brushed the surface of Wendell Pruitt. The rover acquired a single-frame, lossless-compression (highly detailed) image of the area in front of the rover using the navigation camera. Spirit relayed data at UHF frequencies to NASA's Odyssey orbiter for transmission to Earth.

Sol 1480: Spirit acquired column 1, part 3 of the Bonestell panorama and measured argon gas in the Martian atmosphere with the alpha-particle X-ray spectrometer.

Sol 1481: Spirit acquired column 2, part 1 of the Bonestell panorama, and recharged the batteries.

Sol 1482: Spirit acquired an image with the panoramic camera pointing south, then completed "Grind Scan2" of the surface of "Wendell Pruitt." The rover acquired a single-frame, lossless-compresson image of the area in front of the spacecraft with the navigation camera. Spirit relayed data at UHF frequencies to NASA's Odyssey orbiter for transmission to Earth.

Sol 1483 (March 5, 2008): Early in the day, Spirit acquired a super-resolution image of the target nicknamed "FredericBrown half" with the panoramic camera. The rover recharged the batteries. The following morning, Spirit was to acquire full-color, panoramic camera images of column 2, part 2 of the Bonestell panorama.

Odometry

As of sol 1482 (March 4, 2008), Spirit's total odometry remained at 7,528.07 meters (4.68 miles).




Sturdy Rover Gets No Penalty for Tilting

Sols 1471-1477, March 12, 2008

Scarcely a pinball wizard on Earth could tilt the machine nearly 30 degrees without ending play, yet engineers tilted NASA's Spirit rover 29.9 degrees and completed the robotic equivalent of a one-armed toe-touch to test its stability. The rover remained in play, racking up scientific data points after remaining perfectly balanced even while pressing the ground with the Mössbauer spectrometer at the end of its robotic arm.

During the past week, Spirit began work on a 360-degree, full-color panorama of the rover's winter surroundings as viewed from the north edge of the elevated, volcanic plateau known as "Home Plate." The resulting mosaic of high-resolution images, to be acquired during approximately 60 individual pointings of the panoramic camera, will be nicknamed the "Bonestell panorama" in honor of Chesley Bonestell (pronounced BON-es-tell), a science fiction illustrator and designer. (Last year's spectacular image mosaic of Spirit's winter haven was called the "McMurdo panorama.")

Spirit took microscopic images of dust that has settled out of the Martian sky onto the solar panels. The rover also made two attempts to complete the first of a two-part process for brushing the surface of a rock target dubbed "Wendell Pruitt" with the rock abrasion tool, another of the instruments on the rover's robotic arm. Because the results were inconclusive after the first try, Spirit's handlers decided to have the rover repeat the procedure, known as a "grind scan," during which the rover locates the surface by touching it with the brush and the grinding bit, two days later. The second attempt was successful, clearing the way for actual brushing of Wendell Pruitt.

Spirit is healthy and all subsystems are performing as expected.

Sol-by-sol summary

In addition to measurements of atmospheric dust levels with the panoramic camera and daily communications activities, which include morning direct-from-Earth uplinks over the rover's high-gain antenna and evening relays to Earth via the UHF antenna on the Mars Odyssey orbiter, Spirit completed the following activities:

Sol 1471 (Feb. 22, 2008): Spirit completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer, touched the ground and exerted 10 newtons of force with the Mössbauer spectrometer to test the rover's stability at the new tilt of 29.9 degrees, and acquired super-resolution images of a target dubbed "Gekko." Spirit took spot images of the sky for calibration purposes using the panoramic camera.

Sol 1472: Spirit checked for drift (changes over time) in the miniature thermal emission spectrometer, surveyed the external calibration target and completed a mini-survey of the sky and ground with the miniature thermal emission spectrometer, and acquired super-resolution images of a rock target known as "Monolith" with the panoramic camera.

Sol 1473: Spirit acquired full-color images, using all 13 filters of the panoramic camera, of a rock target dubbed "William A. Johnston," a deceased member of the Tuskegee Airmen. Spirit checked for drift in the miniature thermal emission spectrometer, completed a mini-survey of the sky and ground with the instrument, and acquired a 2-by-2-by-1 stack of microscopic images of a target on the rover's solar panels as well as microscopic images of the external capture magnet and filter magnet. The rover acquired single-frame, lossless-compression (high-definition) images of the area directly in front of the rover with the navigation camera.

Sol 1474: Spirit monitored dust on the rover mast, surveyed the sky at varying elevations and the ground with the miniature thermal emission spectrometer, completed another mini-survey of the sky and ground, and checked for drift in the spectrometer.

Sol 1475: Spirit took full-color images, using all 13 filters of the panoramic camera, of a rock target nicknamed "Bennett Hardy" (also a Tuskegee Airman). The rover checked for drift in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit made the first attempt to use a grind-scan procedure to contact the surface of Wendell Pruitt. The rover took single-frame, lossless-compression (high-definition) images with the navigation camera.

Sol 1476: Spirit acquired super-resolution images of a rock target dubbed "Reuben C. Franklin" (a Tuskegee Airman) with the panoramic camera, checked for drift in the miniature thermal emission spectrometer, and completed a mini-survey of the sky and ground with the instrument. The rover took diagnostic images of the rock abrasion tool and recharged the batteries.

Sol 1477 (Feb. 28, 2008): Spirit acquired column 1 of part 1 of the full-color Bonestell panorama, using all 13 filters of the panoramic camera. The rover checked for drift in the miniature thermal emission spectrometer and completed a mini-survey of the sky and ground with the instrument. Spirit completed the second, successful attempt to locate the surface of Wendell Pruitt using the grind-scan procedure with the rock abrasion tool. The rover acquired single-frame, lossless-compression images with the navigation camera. Plans for the following morning called for Spirit to point the panoramic camera starboard and take thumbnail images of the sky.

Odometry

As of sol 1476 (Feb. 27, 2008), Spirit’s total odometry remained at 7,528.07 meters (4.68 miles).




Tenacious Rover Just Might Make It

Sols 1464-1470, March 3, 2008

Spirit has achieved a northerly tilt of 29.9 degrees! As a result, based on power projections, Spirit has a fighting chance of surviving another winter on Mars, if the weather and environment cooperate.

Plans for sol 1471 (Feb. 22, 2008) called for a test of the stability of Spirit's new perch prior to using the rock abrasion tool by having the rover touch the Martian surface with the Mössbauer spectrometer and apply 10 newtons of pressure (called a pre-load).

Sol-by-sol summary

In addition to measurements of atmospheric dust levels with the panoramic camera and daily communications activities, which include morning direct-from-Earth uplinks over the rover's high-gain antenna and evening relays to Earth via the UHF antenna on the Mars Odyssey orbiter, Spirit completed the following activities:

Sol 1464 (Feb. 14, 2008): Spirit edged downslope another 4 centimeters (about 1.5 inches). The rover took thumbnail images of the sky for calibration purposes with the panoramic camera.

Sol 1465: Spirit took mid-field images and spot images of the sky for calibration purposes with the panoramic camera.

Sol 1466: Spirit acquired images for updating the rover's precise attitude relative to the Sun, surveyed the horizon and took spot images of the sky with the panoramic camera, and surveyed the external calibration target with the miniature thermal emission spectrometer.

Sol 1467: Spirit acquired images of the "El Dorado" dune field with the panoramic camera and snapped movie frames in search of dust devils with the navigation camera. The rover took thumbnail images of the sky with the panoramic camera.

Sol 1468: Spirit surveyed the sky at high Sun using the panoramic camera.

Sol 1469: Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and took before-and-after stereo images with the navigation camera to enable the on-board visual odometry software to determine the rover's position. Spirit acquired a 5-by-1 mosaic of forward-looking images and a 5-by-1 mosaic of rearward-looking images with the navigation camera. Also with the navigation camera, the rover assessed atmospheric opacity caused by dust and scanned the sky for clouds.

Sol 1470 (Feb. 21, 2008): Spirit unstowed the robotic arm and moved it to test the rover's stability. Spirit measured atmospheric opacity caused by dust using both the panoramic and navigation cameras. The rover took spot images of the sky with the panoramic camera and surveyed the sky and ground with the miniature thermal emission spectrometer.

Odometry

As of sol 1470 (Feb. 21, 2008), Spirit's total odometry was 7,528.07 meters (4.68 miles).




Spirit Inches Downward

Sols 1457-1463, February 20, 2008

Spirit is tiptoeing ever so carefully down the north edge of the elevated volcanic plateau known as "Home Plate." Having completed a 4-centimeter (1.6-inch) drive on sol 1463 (Feb. 13, 2008), the rover's current northerly tilt is 27.1 degrees. Spirit's handlers plan to have the rover drive another 4 centimeters on sol 1464 (Feb. 14, 2008).

They expect Spirit to be at the rover's final winter perch by the end of next week, following a few more 4-centimeter drives. Given recent progress, Spirit may achieve a northerly, Sun-facing tilt of 30 degrees, higher than originally anticipated. Spirit remains healthy.

Sol-by-sol summary

In addition to measurements of atmospheric dust levels with the panoramic camera and daily communications activities, which include morning direct-from-Earth uplinks over the rover's high-gain antenna and evening relays to Earth via the UHF antenna on the Mars Odyssey orbiter, Spirit completed the following activities:

Sol 1457 (Feb. 7, 2008): Spirit surveyed the Martian sky and ground using the miniature thermal emission spectrometer, stowed the rover's robotic arm, and drove downslope.

Sol 1458: Spirit acquired images of the dune field known as "El Dorado," surveyed the Martian horizon, and took spot images of the sky for calibration purposes using the rover's panoramic camera. Spirit acquired movie frames in search of dust devils using the navigation camera.

Sol 1459: Spirit drove 12 centimeters (4.7 inches) further down the north edge of Home Plate. The rover surveyed the sky and ground with the miniature thermal emission spectrometer.

Sol 1460: Spirit surveyed the sky and ground using the miniature thermal emission spectrometer and took thumbnail images of the sky with the panoramic camera.

Sol 1461: Spirit acquired mid-field and far-field images using the panoramic camera.

Sol 1462: Spirit acquired a second set of mid-field images as well as thumbnail images of the sky using the panoramic camera.

Sol 1463 (Feb. 13, 2008): Spirit drove another 4 centimeters (1.6 inches) downslope. Using the panoramic camera, Spirit surveyed the horizon, monitored changes in the El Dorado dune field, and took spot images of the sky.

Odometry

As of sol 1463 (Feb. 13, 2008), Spirit's total odometry was 7,528.01 meters (4.68 miles).



Dust on Spirit's Solar Panels Increases as Dust in the Atmosphere Decreases

Sols 1450-1456, February 19, 2008

Spirit is healthy and all subsystems are operating as expected. Energy has been steady at about 260 watt-hours per Martian day, or sol (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). On Sol 1450 (Jan. 31, 2008), measurements of atmospheric opacity caused by dust -- known as Tau -- increased by 0.02 to 0.4, then fell back to 0.38, then drifted lower still to 0.333. Small changes such as these are typical of sol-by-sol variations during Martian fall and winter. As the atmosphere cleared, however, a different measurement known as the dust factor -- an estimate of the ability of sunlight to penetrate the layer of dust on the solar arrays -- also dipped slightly and continued to slowly decline, causing overall energy levels to remain about constant.

The dust factor is now 0.374, meaning that only about three-eighths of the sunlight reaching the arrays penetrates the dust layer to generate electricity. The dust factor continues to set new lows nearly every sol. The good news is that the decline has been slower than predicted, resulting in absolute values that are higher than predicted. The difference isn't great -- about 10 to 15 watt-hours, or enough energy to light a 15-watt sewing machine bulb for one hour -- but every bit is welcome.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, measuring atmospheric dust levels with the panoramic camera, checking for drift (changes in time) in the miniature thermal emission spectrometer, and surveying the sky and ground with the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1450 (Jan. 31, 2008): Spirit brushed the surface of the rock target known as "Freeman" (commemorating the Freeman Field Mutiny, a series of attempts in 1945 by African-Americans in the U.S. Air Force to integrate an all-white officers' club) using the wire brush on the rock abrasion tool. Spirit took high-resolution images with the navigation camera to verify on-board software measurements of rover slippage based on comparison of before-and-after stereo images of the terrain (the software is known as the visual odometry system). After communicating with the Odyssey orbiter, the rover acquired panoramic-camera images of the sunset.

Sol 1451: Spirit acquired data from a rock known as "Fuzzy Smith" using the miniature thermal emission spectrometer.

Sol 1452: Spirit took measurements of the external calibration target with the miniature thermal emission spectrometer and acquired a 2-by-2-by-5 mosaic of stereo microscopic images of the brushed surface of Freeman. The rover then placed the alpha-particle X-ray spectrometer on Freeman.

Sol 1453: Spirit took measurements of the external calibration target, a rock target known as "Winston_Gaskins3," and the background of Fuzzy Smith (the specific target was nicknamed "Fuzzy Smith bg2") using the miniature thermal emission spectrometer. After sending data to the Odyssey orbiter, Spirit spent about 6.3 hours integrating data from the brushed surface of Freeman with the alpha-particle X-ray spectrometer.

Sol 1454: Spirit took measurements of the external calibration target with the miniature thermal emission spectrometer.

Sol 1455: Spirit surveyed the external calibration target with the miniature thermal emission spectrometer and, after communicating with Odyssey, spent about 6.3 hours collecting additional data from Freeman with the alpha-particle X-ray spectrometer.

Sol 1456 (Feb. 6, 2008): Spirit took measurements of the external calibration target with the miniature thermal emission spectrometer. The following morning, the rover was to acquire full-color images, using all 13 filters of the panoramic camera, of a rock target known as "Samuel_Hughes."

Odometry

As of sol 1455 (Feb. 5, 2008), Spirit's total odometry remained at 7,527.83 meters (4.68 miles).



Spirit Takes Steps to Conserve Energy During Martian Winter

Sols 1445-1449, February 14, 2008

Spirit is responding to declining winter power levels by dipping into the batteries on one sol (Martian day), then recharging them on the next. In addition, one of the first things the rover did to conserve energy was eliminate afternoon data transfers to the Odyssey orbiter on days when the batteries were being recharged. Though this approach meant the rover wouldn't be able to send data on those sols, it saved enough energy to be worth the sacrifice. As Martian winter deepens, it's possible that, as the Opportunity rover did during the depth of the dust storm a few months ago, Spirit will use only every third Odyssey pass or adopt even more stringent power-conserving measures.

Meanwhile, Spirit remains healthy. For the most part, all subsystems are performing as expected. Energy has been holding steady in the range of 260 watt-hours. Tau (atmospheric opacity) continues to decline slightly, but the dust factor (the ability of sunlight to penetrate dust on the solar panels) also continues to decline slightly.

The winter Sun continues to dip lower in the sky. As of sol 1450 (Jan. 31, 2008), the noontime Sun was 64.6 degrees above the northern horizon, indicating that the optimal northern tilt of the rover deck would be 25.4 degrees from vertical (90 - 64.6 = 25.4). Spirit's current northward tilt is 22 degrees, relatively close to optimal. By mid-February, the optimal tilt will increase to about 28 degrees, the maximum Spirit is anticipated to be able to achieve. That's about the time when rover drivers plan to have the rover complete one more short drive to get into position for the winter.

The orbiting Odyssey spacecraft continues to provide a relay from the rovers to Earth. Each rover sends data to Odyssey via a UHF link. (UHF is "Ultra High Frequency" and represents the same band of frequencies used by the UHF channels on a TV set, channels 14-83, which transmit signals at roughly 400-500 megahertz.) Odyssey stores the data until it can transmit it to Earth using the X-band link. X-band is a microwave frequency that operates at roughly 7-8 gigahertz (megahertz and gigahertz refer, respectively, to millions of cycles per second and billions of cycles per second).

Originally, the Mars rover mission was intended to be an X-band mission, with the rovers using their X-band transmitters to return data directly to Earth. The UHF radio was intended to serve as a backup. But because relay operations via Odyssey proved wildly successful, Odyssey became the preferred avenue for returning data. For one thing, the UHF link can accommodate data at either 128 kilobits per second or 256 kilobits per second (in these cases, "kilo" actually means 1,024 rather than the usual 1,000). The highest X-band data rate for the rovers is only 28.4 kilobits per second, and most of the time, even that rate is unachievable. Odysssey, however, can return data at up to 124.4 kilobits per second using the X-band link. In fact, the lowest rate of data transmission from Odyssey is the same as the highest rate for the rovers.

During the past week, Spirit twice conducted a "grind scan" procedure with the rock abrasion tool. After the tool's encoder failed some time ago, engineers redesigned how the tool is used. Part of that redesign includes doing a "scan" before the rover grinds or brushes any surface (except, of course, that Spirit is no longer grinding into rock surfaces -- after performing more than 10 times longer than expected and contributing a great deal of science data to the mission, the grind bit wore out.)

During the "scan" procedure, the rover pushes the brush and bit into a targeted surface until it measures an increase in electrical current, which implies contact with the rock surface. Detecting the exact location of a possibly irregular surface is important for safely operating the rock abrasion tool.

The only reason Spirit is using the rock abrasion tool at this time is that the rover has moved to a new location as of sol 1440 (Jan. 21, 2008). As Spirit inches down the north-facing slope of "Home Plate," the rover will sample each new location for insight into how the rocks change and how Home Plate was formed.

As Spirit is stationed on a fairly steep slope, engineers have been concerned that moving the robotic arm might cause the rover to slip. The arm is very light and represents only a percent or two of Spirit's weight, but on a slope, it's always possible that even a slight shift could cause a slide. On top of that, the "grind scan" function requires the rover to press down on ("preload") the target. The pressure isn't much, only 15 newtons (not quite 3.5 pounds), but that, too, could conceivably cause a slip. The rover's handlers have created a plan that includes some safety checks.

The first time around, based on receipt of erroneous data, they had to double-check that the slope beneath the rover didn't exceed 20 degrees, the maximum slope previously allowed. Because Spirit was already tilted 22.4 degrees, the safety check tripped immediately and the rover did not conduct any of the planned activities with the rock abrasion tool. Rover handlers re-planned the activities and successfully completed the "scan" procedure on sol 1448 (Jan. 29, 2008).

The next step will be to actually brush the surface. But that's a story for another week.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, measuring atmospheric dust levels with the panoramic camera, and checking for drift (changes in time) in the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1445 (Jan. 26, 2008): Spirit conducted a grind scan procedure at a target called "Freeman." Spirit took high-resolution images with the navigation camera to verify on-board software measurements of rover slippage based on comparison of before-and-after stereo images of the terrain (the software is known as the visual odometry system).

Sol 1446: Spirit re-took part 12 of a mosaic of images of the rover deck and took thumbnail images of the sky with the panoramic camera. The rover acquired data from rock targets known as "Fuzzy_Smith_2" and "Winston_Gaskins_2" using the miniature thermal emission spectrometer.

Sol 1447: Spirit monitored dust accumulation on the rover mast, completed a survey of rock clasts with the panoramic camera, and surveyed the external calibration target, the sky, and the ground with the miniature thermal emission spectrometer.

Sol 1448: Spirit took spot images of the sky and surveyed the horizon with the panoramic camera and scanned the sky for clouds with the navigation camera. The rover monitored changes in the distant dune field known as "El Dorado" with the panoramic camera. Spirit conducted a grind scan at Freeman with the rock abrasion tool. Spirit took high-resolution images with the navigation camera to verify on-board software measurements of rover slippage based on comparison of before-and-after stereo images of the terrain.

Sol 1449: (Jan. 30, 2008): Spirit surveyed the sky and ground with the miniature thermal emission spectrometer and acquired movies in search of dust devils using the navigation camera. The following day, plans called for the rover to survey the external calibration target using the miniature thermal emission spectrometer.

Odometry

As of sol 1448 (Jan. 29, 2008), Spirit’s total odometry remained at 7,527.83 meters (4.68 miles).




Atmospheric Dust Levels Decline Slightly for Spirit

Sols 1437-1444, February 12, 2008

Spirit received some welcome news, as atmospheric dust levels decreased slightly, enabling power levels to remain fairly steady at 260 watt-hours to 270 watt- hours, even as the Martian sun continued to sink toward the northern horizon. (One hundred watt-hours is the amount of energy needed to light a 100-watt bulb for one hour.) Tau measurements of atmospheric opacity decreased from 0.44 to 0.36. The dust factor -- representing the fraction of predicted solar power actually generated after blocking of sunlight by dust on the solar panels -- was nearly steady, declining only 0.05 from 0.39 to 0.385.

Spirit remained perched on the north edge of "Home Plate," a slightly bowl-shaped surface feature with a raised rim that, along its northern edge, is roughly 2 meters (6 feet) above the surrounding area. Directly below Spirit, the slope is about 28 degrees. As Martian winter approaches and the Sun gets lower and lower in the sky, engineers will direct Spirit farther and farther down the slope, increasing the rover's tilt to follow the sun.

As of Sol 1444 (Jan. 25, 2008), Spirit's 22.4-degree northerly tilt was almost perfectly matched to the position of the Sun, which is about 22 degrees below the zenith (the point in the Martian sky directly above the rover). In roughly two to three weeks, Spirit will be adjusted to a final winter position with an expected tilt of about 28 degrees to the north. This will be the best Spirit can do, given the absence of steeper slopes in the vicinity. Even if there were steeper slopes nearby, safety concerns would probably preclude their use.

With more dust on the solar arrays than ever before in the mission, Spirit's third winter will be especially challenging. Estimates indicate that at the winter solstice, the point where the noontime sun will be lowest in the sky, Spirit's energy production will be near the edge of survival. But with Tau and dust accumulation both slightly better than expected and with careful management, the rover's handlers are hopeful that Spirit will ride out the winter and begin roving again in the spring.

While parked for the winter, Spirit will not be idle. Except for the period of very lowest power, the rover will be studying the atmosphere, watching for clouds, monitoring the dust accumulation, checking for frost, and surveying the immediate surroundings, along with completing other tasks.

One of the ways the rover maximizes efficiency is by replacing a large amount of redundant data with a smaller amount of data. This is known as image compression. A simple, everyday analogy is multiplication, in which the mathematical operation, (5 * 4), takes fewer characters than (4 + 4 + 4 + 4 + 4). The rover uses a process called lossless compression, or LOCO for short. There are two classes of compression, lossless and lossy. Lossy compression is sort of like standard television, producing images that are usually sufficient. Lossless compression is analogous to high-definition television and is used for a few images that need to be mathematically processed to include all the detail the cameras can capture. For Spirit, lossless compression is particularly important for collecting detailed images of the area in front of the rover directly after moving to a new location. It is used to generate maps of surfaces reachable with the robotic arm and each of the instruments, called "reachability maps," as well as mathematical models of the area around the rover that are used to simulate the rover's motion during planning, called "terrain meshes." Lossless compression is also used to create slope maps that show steepness and orientation toward the Sun.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna and measuring atmospheric dust levels with the panoramic camera, Spirit completed the following activities:

Sol 1437 (Jan. 18, 2008): Spirit communicated with the Odyssey orbiter while surveying the background of the rock known as "Fuzzy Smith" with the miniature thermal emission spectrometer.

Sol 1438: Spirit surveyed the sky and ground with the miniature thermal emission spectrometer, surveyed the horizon with the panoramic camera, and checked for drift -- changes with time -- in the miniature thermal emission spectrometer.

Sol 1439: Spirit acquired full-color images of the external dust capture magnets using all 13 filters of the panoramic camera, took spot images of the sky with the panoramic camera, and checked for drift in the miniature thermal emission spectrometer. The rover studied Fuzzy Smith and a rock known as "Winston Gaskins" with the miniature thermal emission spectrometer.

Sol 1440: Spirit acquired several panoramic camera images of the rover deck, scanned the sky for clouds with the navigation camera, and took spot images of the sky with the panoramic camera. The rover checked for drift in the miniature thermal emission spectrometer and adjusted position to achieve a greater northerly tilt. After adjusting position, Spirit took images with the hazard avoidance cameras and a single-frame LOCO image with the navigation camera.

Sol 1441: Spirit surveyed the horizon with the panoramic camera, surveyed the external calibration target with the miniature thermal emission spectrometer, and watched for dust devils. The rover also checked for drift in the miniature thermal emission spectrometer.

Sol 1442: Spirit acquired a 1-by-1 panoramic camera mosaic of the work volume reachable with the robotic arm and took thumbnail images of the sky with the panoramic camera. Spirit checked for drift in the miniature thermal emission spectrometer, unstowed the robotic arm, acquired diagnostic images of the rock abrasion tool with the hazard avoidance and panoramic cameras, and exchanged tools to the alpha-particle X-ray spectrometer. The rover sent data to Odyssey during the overhead pass of the orbiter.

Sol 1443: Spirit acquired a 5-by-1 standard tier of images as well as a 5-by-1, rearward-looking mosaic of images with the navigation camera. The rover conducted a horizon survey and acquired more images of the rover deck with the panoramic camera. Spirit checked for drift in the miniature thermal emission spectrometer, communicated with the Odyssey orbiter, and spent 6.75 hours acquiring data with the alpha-particle X-ray spectrometer.

Sol 1444 (Jan. 25, 2008): Spirit surveyed the sky at high Sun with the panoramic camera and checked for drift in the miniature thermal emission spectrometer. The following morning, the rover was to scan the sky for clouds with the navigation camera and take spot images of the sky with the panoramic camera.

Odometry

As of sol 1444 (Jan. 25, 2008), Spirit's total odometry was 7,527.83 meters (4.68 miles).



Spirit Continues to Increase Northerly Tilt

Sols 1430-1436, February 12, 2008

Spirit is currently engaged in a campaign of short bumps -- adjustments in position -- that will incrementally increase the rover's northerly tilt to 22 degrees and eventually to 29 degrees by month's end. Spirit is healthy and all subsystems are operating as expected. The latest power levels measured on sol 1436 (Jan. 17, 2008) were 261 watt-hours (by definition, 100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour).

After successfully adjusting position on sol 1429 (Jan. 9, 2008) to achieve a northerly tilt of about 16 degrees, Spirit completed scientific studies of the rock target known as "Chanute." From sols 1431-1433 (Jan. 12-14, 2008), Spirit acquired a microscopic image mosaic of the brushed surface, placed the alpha-particle X-ray spectrometer on the target, and collected compositional data for about six hours. Sol 1433 was a recharge sol with no UHF-band communication. After reviewing the data, scientists agreed there was too much dust and debris in the alpha-particle X-ray spectrometer measurements. They thus decided to move the instrument to a "cleaner" location in the activity plan for sols 1434-1435 (Jan. 15-16, 2008) and collect another six hours worth of data. They documented the new site with a single-frame microscopic image.

Following sol 1435, also a recharge sol with no UHF communication, the rover's handlers planned another bump on sol 1436 (Jan. 17, 2008). Because of power limitations, they delayed a plan to inspect some strange-appearing brush patterns that may indicate normal brush wear or possible damage. They planned to use the miniature thermal emission spectrometer on sol 1437 (Jan. 18, 2008) at the start of a three-part imaging campaign on a rock known as "Fuzzy Smith."

Spirit's bump on sol 1436 was successful and put the rover at a new northerly tilt of approximately 18 degrees. The impact on power will not be known until receipt of data on sol 1437. The science team's goal is to achieve a northerly tilt of 22 degrees as soon as possible, at which point they will likely pause to perform scientific studies of a new target.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, Spirit completed the following activities:

Sol 1430 (Jan. 11, 2008): Spirit monitored atmospheric dust with the panoramic camera.

Sol 1431: Spirit took full-color images of Chanute using all 13 filters of the panoramic camera. The rover monitored atmospheric dust, unstowed the robotic arm, and acquired navigation camera images. Spirit acquired a 2-by-2-by-5 mosaic of stereo microscopic images of the brushed surface of Chanute and placed the alpha-particle X-ray spectrometer on the target. The rover took images following instrument placement with the navigation camera.

Sol 1432: Spirit measured atmospheric opacity caused by dust with the panoramic and navigation cameras and scanned the sky for morning clouds with the navigation camera. The rover acquired compositional data from the brushed surface of Chanute with the alpha-particle X-ray spectrometer.

Sol 1433: Spirit monitored atmospheric dust levels using the panoramic and navigation cameras and scanned the sky for clouds with the navigation camera.

Sol 1434: Spirit measured atmospheric dust with the panoramic and navigation cameras and scanned the sky for clouds with the navigation camera. The rover acquired a 1-by-1-by-1 mosaic and a 1-by-1-by-3 mosaic of microscopic images of the brushed surface of Chanute and placed the alpha-particle X-ray spectrometer on the target. Spirit acquired navigation camera images after placing the spectrometer on the target. The rover communicated with the Odyssey orbiter and acquired data from the brushed target with the alpha-particle X-ray spectrometer.

Sol 1435: Spirit measured atmospheric dust opacity with the panoramic camera and acquired a 5-by-1 mosaic of navigation camera images of the rover deck, a 2-by-1 mosaic of panoramic camera images, and two views of the rover deck with the panoramic camera.

Sol 1436 (Jan. 17, 2008): Spirit took thumbnail images of the sky with the panoramic camera, meaasured atmospheric dust with the panoramic camera, took images of the brush on the rock abrasion tool, and bumped into a new position to increase northerly tilt. The rover took images with the hazard avoidance and navigation cameras after the bump. Spirit also acquired navigation camera images of Fuzzy Smith after the bump. The rover took a 1-by-1 image mosaic of the work volume with the panoramic camera. The following day's plans called for Spirit to measure atmospheric dust with the panoramic camera, monitor dust accumulation on the rover mast, and acquire additional images of the rover deck as well as spot images of the sky with the panoramic camera.

Odometry

As of sol 1436 (Jan. 17, 2008), Spirit's total odometry was 7,527.71 meters (4.68 miles).



Sols 1423-1429, February 12, 2008

Spirit Tilts Toward the Sinking Sun

After directing the rover to brush the surface of the rock target known as "Chanute," engineers placed continued studies on hold while they adjusted Spirit's position to achieve a greater northerly tilt, in the direction of the sinking winter Sun. The latest available power levels measured on sol 1429 (Jan. 9, 2008) were 268 watt-hours, a sobering reminder of the onset of winter. Spirit was in the middle of a campaign of scientific studies with the brush on the rock abrasion tool, alpha-particle X-ray spectrometer, and microscopic imager. The move was successful and gave the rover a new northerly tilt of about 16 degrees.

Spirit is healthy and all subsystems are nominal.

After Spirit had completed acquisition of the "Tuskegee panorama" on sol 1423 (Jan. 3, 2008), planned science activities included brushing the surface of Chanute prior to continued investigation with the alpha-particle X-ray and Mössbauer spectrometers. To locate the surface, the rover performed a "seek scan" with the rock abrasion tool on sol 1424 (Jan. 4, 2008). This activity is a work-around procedure that compensates for a broken encoder and allows the rover to stall the motor of the rock abrasion tool when it makes contact with the surface.

The next two Martian days were recharge sols. Spirit brushed the surface of Chanute on sol 1427 (Jan. 7, 2008). This was also followed by another recharge sol. The rover's handlers then made two significant changes to the strategic plan to address the deteriorating power situation. First, because recharge sols were becoming less and less effective, they decided to begin deleting the UHF passes on these sols, starting on sol 1428 (Jan. 8, 2008). Second, they decided to proceed sooner than anticipated with plans to achieve a steeper northerly tilt of 20 degrees. Activities on sol 1429 (Jan. 9, 2008) involved a bump of 10 centimeters (4 inches) downslope. Sol 1430 (Jan. 11, 2008) was to be a recharge sol with no UHF.

The impact of the new, 16-degree northerly tilt on power will not be known until receipt of further data on sol 1431 (Jan. 12, 2008). The science team's goal is to reach 20 degrees as soon as possible, meaning they will likely execute additional short bumps similar to those of sol 1429 in the very near future. In the meantime, Spirit will complete work on Chanute.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, sending data to Earth at UHF frequencies via the Odyssey orbiter, and measuring atmospheric dust levels, Spirit completed the following activities:

Sol 1423 (Jan. 3, 2008): Spirit acquired a 2-by-1 mosaic of the Tuskegee panorama.

Sol 1424: Spirit acquired a 4-by-1 mosaic of the Tuskegee panorama, performed a seek-scan maneuver to locate the surface of Chanute with the rock abrasion tool, and took navigation camera images following the procedure.

Sol 1425: Spirit acquired a 4-by-1 mosaic of the Tuskegee panorama.

Sol 1426: Spirit acquired morning thumbnail images of the sky with the panoramic camera.

Sol 1427: Spirit acquired spot images of the sky with the panoramic camera, monitored dust on the panoramic camera mast assembly, and scanned the sky for clouds with the navigation camera. The rover brushed the surface of Chanute, stowed the robotic arm, and acquired navigation camera images of the brushed surface.

Sol 1428: Spirit acquired a 4-by-1 mosaic of images of the Tuskegee panorama.

Sol 1429 (Jan. 9, 2008): Spirit surveyed the sky at low Sun with the panoramic camera, bumped downslope, took images with the hazard avoidance cameras, and acquired a navigation camera image after the change in position. The following day's plans called for the rover to survey the horizon with the panoramic camera and acquire movie frames in search of dust devils spaced at 8-minute intervals using the navigation camera.

Odometry

As of sol 1429 (Jan. 9, 2008), Spirit's total odometry remained at 7,527.52 meters (4.68 miles).



Spirit Continues Drive As Power Levels Decline

sol 1363-1369, November 12, 2007

Spirit has been gradually losing power, with energy levels dropping to 320 watt-hours per Martian day (100 watt-hours is the amount of energy needed to light a 100-watt bulb for one hour). Measurements of atmospheric dust, known as Tau, have been averaging 0.65. That dust level is typical of levels measured throughout most of the mission, but power levels are lower than in previous years because of higher dust accumulation on the solar panels. (The rover estimates dust levels by measuring opacity -- the degree to which the atmosphere is impenetrable by light. During most of Spirit's mission on Mars, except during the recent dust storms, tau values have fallen between 0 and 1.)

During the trek to reach the north edge of "Home Plate" before the next Martian winter, Spirit had time to conduct only one scientific campaign. Scientists selected a rock target nicknamed "Pecan Pie" (investigators are nicknaming targets on top of Home Plate for things served in bowls) for closer investigation, at a location known as "Site 5." Spirit brushed Pecan Pie, took pictures of it with the microscopic imager, and analyzed its composition with the alpha-particle X-ray spectrometer. Planned measurements over the weekend included an analysis of iron-bearing minerals with the Mössbauer spectrometer before resuming the drive.

The successful brush of Pecan Pie marked the first time that Spirit had used the new, two-sol brushing procedure that enabled continued use of the rock abrasion tool following the failure of the grind encoder. Spirit continued to collect images of the west side of Home Plate (known as "West Valley" to science team members) while advancing northward. The images are important for understanding the geology as well as for planning the hoped-for, post-winter drive to a hill known as "von Braun" south of Home Plate.

Spirit remains healthy. On Sol 1369 (Nov. 9, 2007), plans called for Spirit to run a diagnostic of the rock abrasion tool by pointing it at the hazard avoidance camera for photo documentation while running the motor at various voltages. The resulting measurements of the spinning of the tool will provide a baseline for eventual failure of the motor and for comparison with Spirit's twin, Opportunity, on the other side of Mars.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, sending evening data to Earth at UHF frequencies via the Odyssey orbiter, measuring atmospheric dust levels with the panoramic camera, and surveying the sky and ground with the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1363 (Nov. 3, 2007): Spirit acquired pre-drive, panoramic camera images of targets known as "Posole," "Green Chile," and "Flan," then drove 24.83 meters (84.46 feet) to Site 5 on Home Plate. The rover acquired post-drive image mosaics with the navigation and panoramic cameras. The next morning, Spirit completed a survey of rock clasts with the panoramic camera and took a mosaic of images with the navigation camera.

Sol 1364: Spirit acquired images of the distant dune field known as "El Dorado" with the panoramic camera, and after communicating with the Odyssey orbiter during its overhead pass, measured atmospheric argon with the alpha-particle X-ray spectrometer. In the morning, Spirit completed a full-color, systematic ground survey using all 13 filters of the panoramic camera.

Sol 1365: Spirit spent the day recharging the battery. The following morning, Spirit searched for dust devils using the navigation camera.

Sol 1366: Spirit placed the rock abrasion tool on Pecan Pie and acquired a mosaic of images known as the "West Valley View" with the panoramic camera. The next morning, the rover took spot images of the sky with the panoramic camera and acquired movie frames in search of dust devils with the navigation camera.

Sol 1367: Spirit acquired another mosaic of images of West Valley View with the panoramic camera. In the morning, Spirit acquired full-color images, using all 13 filters of the panoramic camera, of the rover's tracks.

Sol 1368: Spirit conducted scientific studies of Pecan Pie, including brushing the surface of the rock target with the brush on the rock abrasion tool, acquiring stereo microscopic images of the brushed surface, and collecting 9 hours of compositional data with the alpha-particle X-ray spectrometer. The rover also acquired a mosaic of images of West Valley View with the panoramic camera. The following morning, Spirit took thumbnail images of the sky with the panoramic camera.

Sol 1369 (Nov. 9, 2007): Plans called for Spirit to run diagnostic tests of the rock abrasion tool and acquire a mosaic of images of West Valley View with the panoramic camera. The rover was to spend 22 _ hours acquiring data with the Mössbauer spectrometer, be on the lookout for morning dust devils, and acquire movie frames at 8-minute intervals to record the progress of dust devils if they occurred.

Odometry:

As of sol 1367 (Oct. 30, 2007), Spirit's total odometry was 7,383.75 meters (4.59 miles).





Spirit to Head North for the Winter

sol 1355-1362, November 02, 2007

With Martian winter approaching, the science and engineering teams have been hard pressed to select a site where Spirit can spend the winter. After previously narrowing the list of candidates to two sites, Spirit's handlers decided to send the rover to the northern edge of the elevated plateau known as "Home Plate," which Spirit has been exploring for many months now.

Previously considered sites included "von Braun," "South Promontory," "Batter's Box" ("West Knoll"), and "North Home Plate." The decision means the rover will move farther away from tantalizing, new terrain to the south, but maximizes the rover's chances of surviving another winter given the excessive coating of dust on the solar arrays.

As Project Manager John Callas announced in an e-mail, "the principal discriminator was the achievable slope at each site. The north side of 'Home Plate' offers slopes of 25 degrees of northerly tilt, while 'South Promontory' offers 20 degrees of northerly tilt. That difference is about 10 watt-hours per sol, which can mean the difference between surviving and not surviving the cold, dark winter."

Meanwhile, Spirit remains healthy and all subsystems are nominal. Energy has been averaging 355 watt-hours (100 watt-hours is the amount of electricity needed to light one 100-watt bulb for one hour) and atmospheric dust measurements (Tau) have been steady at about 0.63.

Plans called for Spirit to head in a northerly direction, toward an area known as "Site 5" on top of Home Plate, starting on sol 1362 (Nov. 2, 2007). Once there, Spirit may investigate some targets with instruments on the robotic arm before continuing to the north end of Home Plate.

Meanwhile, engineers working on the rover's miniature thermal emission spectrometer have determined that degradation in performance of the spectrometer on both Spirit and its twin, Opportunity, is the result of dust deposition on the scan mirror or in the panoramic camera mast assembly. They have decided not to use the instrument on Opportunity and to use it only for high-priority targets and weekly atmospheric measurements on Spirit while they try to develop strategies for removing the dust.

In addition, tests run on sols 1355, 1358, and 1360 (Oct. 25, Oct. 29, and Oct. 31) determined that the grind motor on Spirit's rock abrasion tool failed on sol 1341 (Oct. 11, 2007) , as it did previously on Opportunity on sol 1045 (Jan. 1, 2007). However, because the rover's handlers have devised an alternate technique for grinding and brushing that takes two Martian days, they are still able to use the brushes on both rock abrasion tools.

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, sending evening data to Earth at UHF frequencies via the Odyssey orbiter, measuring atmospheric dust levels with the panoramic camera, and surveying the sky and ground with the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1355 (Oct. 25, 2007): Spirit unstowed the robotic arm, conducted imaging diagnostics of the rock abrasion tool, and took microscopic images of the capture magnet. The rover placed the alpha-particle X-ray spectrometer on the capture magnet, took panoramic camera images of the rover deck, and transmitted data overnight via the Odyssey orbiter. Spirit monitored dust on the panoramic camera mast assembly, surveyed the horizon with the panoramic camera, acquired a mosaic of images with the navigation camera, and acquired movie frames in search of dust devils with the navigation camera.

Sol 1356: Spirit acquired panoramic camera images of the rover deck and of rock targets nicknamed "Grays Peak," "Elk," and "San Juan." The rover acquired 6 hours worth of data with the alpha-particle X-ray spectrometer and took thumbnail images of the sky with the panoramic camera.

Sol 1357: Spirit used the navigation camera to survey the surface darkened by the rover's shadow. The rover acquired full-color images of its tracks using all 13 filters of the panoramic camera. Spirit acquired another 6 hours of data with the alpha-particle X-ray spectrometer and took spot images of the sky with the panoramic camera.

Sol 1358: Spirit took images of the filter magnet with the microscopic imager, performed diagnostic tests on the rock abrasion tool, and used the panoramic camera to take images of the rover deck and survey the horizon.

Sol 1359: Spirit turned in place for communications relays and performed a "get quick fine attitude" to check for changes in the inertial measurement unit to determine the rover's precise location. Spirit acquired post-drive images with both the navigation and panoramic cameras. In the morning, the rover completed a systematic ground survey with the panoramic camera.

Sol 1360: Spirit unstowed the robotic arm, performed diagnostic tests of the rock abrasion tool, and acquired a mosaic of microscopic images of a soil target known as "Pumpkin Pie" before placing the alpha-particle X-ray spectrometer on the target. Spirit acquired full-color images, using all 13 filters of the panoramic camera, of another soil target known as "Candy Corn." The rover collected data from Pumpkin Pie with the alpha-particle X-ray spectrometer and in the morning, scanned the sky for clouds with the navigation camera. Spirit also surveyed the horizon with the panoramic camera and acquired movie frames in search of dust devils with the navigation camera.

Sol 1361: Spirit stowed the robotic arm in preparation for the next day's drive and took full-color images, using all 13 filters of the panoramic camera, of Elk and San Juan. The rover acquired a mosaic of images with the navigation camera as part of a 360-degree panorama for drive planning. Spirit surveyed the sky at both low sun and high sun with the panoramic camera.

Sol 1362 (Nov. 2, 2007): Plans called for Spirit to drive toward Site 5, acquire full-color, mid-drive images of Pumpkin Pie with all 13 filters of the panoramic camera, and acquire post-drive images with both the navigation and panoramic cameras. The following morning, Spirit was to complete a survey of rock clasts with the panoramic camera and scan the sky for clouds with the navigation camera.

Odometry:

As of sol 1359 (Oct. 30, 2007), Spirit's total odometry was 7,339.70 meters (4.56 miles).



Spirit Considers Options for Surviving Another Winter on Mars

sol 1348-1354, October 30, 2007

Spirit's handlers are currently confronted with the decision of where to send the rover for the winter. Dust deposition on the rover's solar panels, a product of the recent dust storms, has made power predictions for the upcoming winter even worse than those experienced during Spirit's last Martian winter. Members of the science team hope to find a place where Spirit can achieve a tilt of 20 degrees or more toward the north, facing the sun.

During the week, Spirit drove approximately 50 meters (164 feet) in a southerly and southeasterly direction toward a potential off-ramp from the top of the elevated plateau known as "Home Plate."

Proposed locations for a winter haven include driving south down the off-ramp and making a break for "von Braun," a hill approximately 120 meters (390 feet) away; heading north across Home Plate and driving down the north-facing edge; or driving west of Home Plate to a hill tentatively identified as "West Knob."

On sols 1349 and 1351 (Oct. 19 and Oct. 21, 2007), Spirit acquired long-baseline stereo images of von Braun, to the south of Home Plate.

Spirit has been generating approximately 345 watt-hours of solar array energy (enough to run a 100-watt bulb for almost 3 1/2 hours) per Martian day (or sol). Measurements of atmospheric dust opacity, known as Tau, have been approximately 0.7 (higher Tau measurements correspond to more dust).

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, sending evening data to Earth at UHF frequencies via the Odyssey orbiter, measuring atmospheric dust levels with the panoramic camera, and surveying the sky and ground with the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1348 (Oct. 18, 2007): Spirit drove approximately 14 meters (46 feet) to get into position for the first "eye," or vantage point, of the long-baseline stereo panorama. The rover took a 7-by-1, post-drive image mosaic, measured the thermal characteristics of the external calibration target with the miniature thermal emission spectrometer, and acquired thumbnail images of the sky with the panoramic camera.

Sol 1349: Spirit created a list of files on board and then proceeded to acquire the left-eye portion of the long-baseline stereo panorama. The rover relayed data to Earth during the overnight pass of the Odyssey orbiter, completed a systematic ground survey using all 13 filters of the panoramic camera, and took spot images of the sky with the panoramic camera.

Sol 1350: Spirit drove approximately 8 meters (26 feet) to the second vantage point for the long-baseline stereo view and then acquired a post-drive image mosaic (a 6-by-1 panel) with the navigation camera. The rover acquired images of the external magnets through all filters of the panoramic camera.

Sol 1351: Spirit acquired the right-eye portion of the long-baseline stereo panorama and spent 6 1/2 hours collecting measurements of atmospheric argon with the alpha-particle X-ray spectrometer. The rover surveyed the horizon with the panoramic camera and watched for dust devils.

Sol 1352: Spirit acquired pre-drive images with the panoramic camera to fill in portions of the right-eye view of the stereo image mosaic. The rover drove approximately 6 meters (20 feet) south-southeast toward the potential south off-ramp of Home Plate and acquired a 5-by-1 mosaic of images with the navigation camera as well as a 4-by-1 mosaic of images with the panoramic camera. Spirit took spot images of the sky, conducted a survey of rock clasts with the panoramic camera, and searched for dust devils with the navigation camera.

Sol 1353: Spirit drove approximately 10 meters (33 feet) south-southeast toward the potential south off-ramp and acquired a 5-by-1, post-drive image mosaic with the navigation camera and a 4-by-1, post-drive image mosaic with the panoramic camera. The rover surveyed the horizon and completed a survey of rock clasts with the panoramic camera. Spirit watched for dust devils.

Sol 1354 (Oct. 24, 2007): Spirit acquired a 4-by-1, pre-drive panel of images of "West Knob" with the panoramic camera and drove approximately 12 meters (39 feet) south-southeast toward the potential off-ramp. The rover acquired a 5-by-1, post-drive image mosaic with the navigation camera and a 4-by-1 image mosaic with the panoramic camera. Spirit tested communications with the Mars Express orbiter, a European Space Agency mission, in preparation for next year's arrival of NASA's Phoenix lander. The rover completed a systematic ground survey and horizon survey with the panoramic camera.

Odometry:

As of sol 1354 (Oct. 24, 2007), Spirit's total odometry was 7,338.78 meters (4.56 miles).



Spirit Continues Studies of Rocks on "Home Plate"

sol 1343-1347, October 29, 2007

Spirit is healthy and continues to investigate "Home Plate." After completing extensive studies of "Site 3" using the Mössbauer spectrometer and other instruments, the rover proceeded toward "Site 4."

Meanwhile, it's already time for Spirit to start thinking about winter again. Over the coming weekend, the rover was scheduled to acquire long-baseline stereo images of Home Plate and surrounding areas in search of a safe winter haven.

The grinding encoder on Spirit's rock abrasion tool appears to have suffered the same fate as that of Spirit's twin, Opportunity, on the other side of Mars. An investigation is under way, but all indications are that activities using the rock abrasion tool will now require two Martian days, or sols.

On sol 1346 (Oct. 16, 2007), Spirit drove approximately 10 meters (33 feet) toward Site 4 and added another 12 meters (39 feet) of driving on sol 1347 (Oct. 17, 2007).

Sol-by-sol summary

In addition to receiving morning instructions directly from Earth via the high-gain antenna, returning data in the evening at UHF frequencies via the Odyssey orbiter, measuring atmospheric dust levels (known as tau measurements) with the panoramic camera, and surveying the sky and ground with the miniature thermal emission spectrometer, Spirit completed the following activities:

Sol 1343 (Oct. 13, 2007): Spirit restarted the Mössbauer spectrometer and collected data for 22 hours with the instrument from a target called "Humboldt Peak." The rover acquired remote data from a rock target known as "Mt. Eolus" with the miniature thermal emission spectrometer and a 6-by-1 image mosaic with the panoramic camera.

Sol 1344: Spirit restarted the Mössbauer spectrometer and resumed data collection from Humboldt Peak for 23 hours. The rover acquired spot images of the sky and a 4-by-1 image mosaic with the panoramic camera and collected remote data from a rock known as "Pikes Peak" using the miniature thermal emission spectrometer.

Sol 1345: Spirit resumed collecting Mössbauer data from Humboldt Peak for another 23 hours. The rover acquired remote data from a target dubbed "Mt. Sneffels" with the miniature thermal emission spectrometer and spot images of the sky with the panoramic camera. Spirit monitored dust on the rover mast assembly.

Sol 1346: Spirit ran tests on the rock abrasion tool and stowed the robotic arm before taking pre-drive images with the panoramic camera and driving about 10 meters (33 feet) toward Site 4 on Home Plate. The rover acquired a 5-by-1, post-drive image mosaic with the navigation camera as well as a 4-by-1 mosaic with the panoramic camera. The rover took spot images of the sky and foreground images with the panoramic camera.

Sol 1347 (Oct. 17, 2007): Spirit conducted a pre-drive survey of the rover's surroundings with the p