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SPACE FLIGHT 2006 - The Year in Review

United States Space Activities

Launch activities in the United States in 2006 showed a solid increase from the previous year. There were 22 NASA, DOD, and commercial launches, out of 23 attempts (2005: 16 of 16 attempts, 2004: 19 of 19; 2003: 26 of 27 [loss of Columbia]).

Space shuttle

After the loss of Orbiter Columbia on the first (and only) shuttle mission in 2003, the space shuttle returned to the skies in Summer 2005 with the liftoff of STS-114/Discovery. But with more work required on redesign of the foam-based insulation on the space shuttle's external tank, new sensors for detailed damage inspection and a boom to allow astronauts to inspect the vehicle externally during flight, the second RTF test flight was delayed until well into 2006. During the stand-down and continuing after RTF until STS-121, resupply and crew rotation flights to the ISS were accomplished solely by Russian Soyuz and Progress vehicles.

STS-121

After two launch scrubs on July 1 and 2 due to weather concerns, Discovery, on its 32nd flight, lifted off on the second RTF mission (ISS-ULF1.1) on July 4, 2006 (2:38pm EDT), carrying the crew of Commander Steven Lindsey, Pilot Mark Kelly, Mission Specialists Stephanie Wilson, Michael Fossum, Piers Sellers, Lisa Nowak, and Expedition 13 (later Expedition 14) crewmember Thomas Reiter, plus 28,120 lbs (12,755 kg) of equipment & supplies in its cargo bay.  The orbiter's thermal protection system was carefully inspected for damage before docking at the station on 7/6 (10:52am). Hatches were opened at 12:30pm as station occupancy increased to nine persons. The crew transferred the loaded Italian-built MPLM (Multi-Purpose Logistics Module) Leonardo to the station, handing it over from the shuttle's Remote Manipulator System (SRMS) to the Space Station Remote Manipulator System (SSRMS), performed three successful EVAs, transferred cargo between the space vehicles, and reberthed the MPLM with return cargo in the shuttle cargo bay. Leaving Thomas Reiter, the first European long-duration station resident at the ISS, flying under contract with the Russian Federal Space Agency Roskosmos, Discovery undocked on 7/15 at 6:08am and returned to Earth on 7/17, touching down smoothly on Runway 15 at Kennedy Space Center (KSC) at 9:15am EDT after 202 orbits. Total mission duration of the 5.8 million-mile journey in space was 13d 6h 37m.

STS-115

Several launch scrubs preceded the liftoff of Atlantis, such as a lightning strike on August 25, a fuel cell problem on September 6 and a faulty sensor reading on September 8. The launch of Atlantis (ISS Mission 12A) finally succeeded on September 9 at 11:15am EDT, with the crew of Commander Brent Jett, Pilot Chris Ferguson, Mission Specialists Dan Burbank, Heidemarie Stefanyshyn-Piper, Joe Tanner and Canadian Steve MacLean. The orbiter docked at the station on 9/11 at 6:48am.  All objectives were successfully accomplished, in particular resupply of the station and resumption of station assembly after a hiatus of four years by delivering the 35,000 lb (17.5 ton) P3/P4 integrated truss structure with the second set of solar arrays (of four). Three spacewalks were performed by Tanner, Piper, Burbank and MacLean to install the P3/P4 truss, deploy the solar arrays and prepare them for operation, i.e., power generation for the station. They were fully unfolded on 9/14 to a wingspan of 240 ft (73 m) on the port side of the station to produce 66 kilowatts (kW) of electricity. Atlantis separated from the ISS on 9/17 at 8:15am after a total docked time of 6 days 2 hours 2 min and returned to Earth on 9/21, touching down at KSC at 6:21am EDT after 186 orbits and a stunningly perfect 12A mission of 11d 19h 06m and a 4.9 million-mile journey in space.

STS-116

Shuttle Discovery launched on December 9 (8:47pm EST) on ISS Mission 12A.1, one of the most challenging shuttle missions in NASA history, carrying the all-rookie crew of Commander Mark Polansky, Pilot William Oefelein and Mission Specialists Nicholas Patrick, Robert Curbeam, Joan Higginbotham, Christer Fuglesang (ESA/Sweden) and Sunita Williams. Docking took place on 9/11 (5:12pm EST), increasing station crew to ten (now including CDR Lopez-Alegria, FE-1 Tyurin and FE-2 Reiter). Hatches were open at 6:53pm. The crew successfully achieved all objectives of the 12-day mission: Delivery and installation of the P5 truss segment (serving as a spacer at the end of the new P4 truss), exchange of an ISS crewmember for another, reconfiguring and activating the new electrical power system and thermal control system, and transferring extra oxygen for EVA prebreathing and nitrogen to storage tanks on the outside of the Quest Airlock. Curbeam, Fuglesang and Williams took turns in pairing up for four EVAs, the last one added to have the spacewalkers manually assist the full retraction of the older P6 solar array, readying it for its relocation during a future mission. Sunita Williams officially replaced Thomas Reiter as Expedition 14 Flight Engineer 2, and Reiter became a member of the 12A.1 crew, returning on Discovery after 168 days on ISS. Discovery undocked from ISS on 12/20 at 5:09pm EST, after a total docked time of 7 days 21 hours, and returned to KSC on 12/22 at 5:32pm after 202 orbits and a 5.3 million-mile trip in space lasting 12d 20h 45m. It was the 117th space shuttle flight, the 33rd by Discovery and the 20th shuttle mission to visit the ISS.

Advanced transportation systems activities.

Constellation Program: NASA continued its early development work on the next generation spacecraft and launch system, announced in 2005 to support the new long-range Vision for Space Exploration mandated by President Bush in 2004. In 2006, NASA's Constellation program entailed the CLV (Crew Launch Vehicle) named Ares 1 with the CEV (Crew Exploration Vehicle) spaceship Orion, capable of delivering crew and supplies to the ISS, carrying four astronauts to the Moon and supporting up to six crewmembers on future missions to Mars, and an uncrewed series of heavy cargo lifters (CaLV) named Ares V, in honor of the mighty Saturn V of the 1960s, whose lifting capability the new Ares V will approach and most likely surpass. Orion will be shaped like an Apollo capsule but will be significantly larger. These systems will take the place of the space shuttle some time after it is decommissioned by end-2010.

On August 31, NASA awarded the contract for DDT&E (Design, Development, Testing & Evaluation) of the Orion CEV to Lockheed Martin Co. Also during 2006, NASA selected the companies SpaceX and Rocketplane/Kistler (RpK) for the COTS (Commercial Orbital Transportation) providers of private-owned launch and delivery systems of cargo, later crews, to the ISS.

Space sciences and astronomy

In 2006, the U.S. launched nine civil science spacecraft (seven more than in the previous year): New Horizons, ST5, CloudSat, CALIPSO, GOES-N, STEREO-A, and STEREO-B.

New Horizons

Humankind's first mission to distant planet Pluto was launched by NASA on January 19 aboard an Atlas V rocket at 2 pm EST. Named New Horizons, the 1,054-lbs (478 kg), piano-sized spacecraft was the fastest ever launched, speeding away from Earth at approximately 36,000 miles per hour on a trajectory that will take it on an unprecedented journey of exploration to the ninth planet in the solar system, traveling more than three billion miles toward its primary science target. New Horizons, which flew past Jupiter for a gravity assist and science studies already in February 2007, will conduct the first close-up, in-depth study of Pluto and its moons in summer 2015. As part of a potential extended mission, the spacecraft would then examine one or more additional objects in the Kuiper Belt, the region of ancient, icy, rocky bodies (including Pluto) far beyond Neptune's orbit. After the Jupiter encounter -- during which New Horizons was to train its science instruments on the large planet and its moons -- the spacecraft will "sleep" in electronic hibernation for much of the cruise to Pluto. Operators will turn off all but the most critical electronic systems and check in with the spacecraft once a year to check out the critical systems, calibrate the instruments and perform course corrections, if necessary. Between the in-depth checkouts, New Horizons will send back a beacon signal each week to give operators an instant read on spacecraft health. The entire spacecraft, drawing electricity from a single radioisotope thermoelectric generator, operates on less power than a pair of 100-watt household light bulbs. New Horizons, developed and controlled at Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., is the first mission in NASA's New Frontiers Program of medium-class spacecraft exploration projects.

ST5

NASA's three Space Technology 5 (ST5) micro-satellites, part of the New Millennium Program (NMP) focused on the design, development, integration and operation of three full-service 25-kg-class spacecraft that implemented multiple new technologies. They were launched on March 22 (9:03 am EST) on an Orbital Sciences Pegasus XL rocket from a L-1011 aircraft from VAFB (Vandenberg Air Force Base), California, each one fully fueled and weighing approximately 55 lbs (25 kg) and about the size of a 13-inch television set. A major mission milestone was reached on May 24 when the spacecraft assumed a constellation formation, lining up in nearly identical orbits, like three pearls on a necklace, approximately 220 miles (350 km) apart. Reaching formation required seven maneuvers using miniaturized micro-thrusters. Each spacecraft has a single micro-thruster the size of a quarter to perform both attitude- and orbit-adjustment maneuvers. The mission demonstrated the benefits of using a constellation of spacecraft to perform scientific studies of the auroral displays occurring near Earth's polar regions. The spacecraft simultaneously traversed electric current sheets and measured the magnetic field using miniature magnetometers. The mission, developed by the Goddard Space Flight Center (GSFC), was completed on June 20, 2006, after providing accurate research-quality scientific measurements. The NMP was created by NASA to identify, develop, build, and test innovative technologies and concepts for use in future missions. Its missions are guided by future needs of NASA's Earth and Space Science program

STEREO-A & STEREO-B.

STEREO (Solar TErrestrial RElations Observatory) is the third mission in NASA's Solar Terrestrial Probes program (STP). The twin STEREO spacecraft were launched on October 25 on a Delta 2 7925-10L rocket from CCAFS (Cape Canaveral Air Force Station) in Florida. The two-year mission of the two nearly identical space-based observatories, one ahead of Earth in its orbit around the sun (STEREO-A, for ahead), the other trailing behind (STEREO-B, behind) will provide the first-ever stereoscopic measurements to study the Sun and the nature of its coronal mass ejections, or CMEs. Scientific objectives are to (a) understand the causes and mechanisms of CME initiation, (b) characterize the propagation of CMEs through the heliosphere, (c) discover the mechanisms and sites of energetic particle acceleration in the low corona & the interplanetary medium, and (d) improve the determination of the structure of the ambient solar wind. The two solar-powered observatories with 3-axis-stabilization, each with a launch mass of 1,364 pounds (620 kilograms, including propellant), were developed by the Johns Hopkins University Applied Physics Laboratory (APL) and communicate with its Mission Operations Center via NASA's Deep Space Network.

Gravity Probe-B

Gravity Probe-B (GP-B) is a NASA mission to test two predictions of Albert Einstein's theory of General Relativity (GR) using four spherical gyroscopes and a telescope, housed in a satellite orbiting 642 km (400 mi) above the Earth, measuring in a new way and with unprecedented accuracy two extraordinary effects predicted by the General Theory of Relativity (the second having never before been directly measured): (a) The geodetic effect - the amount by which the Earth warps the local spacetime in which it resides, (b) the frame-dragging effect - the amount by which the rotating Earth drags its local spacetime around with it. The 3100-kg spacecraft was launched on April 20, 2004, on a Delta 2 rocket. In 2005, almost 90 years after Albert Einstein first postulated his GR and after GP-B orbited Earth for more than 17 months, scientists finished collecting data. Fifty weeks worth of more than a terabyte of science data were downloaded from the spacecraft and relayed to a comprehensive computer database in the Mission Operations Center at Stanford University, Stanford, Calif., where scientists began the painstaking task of data analysis and validation of the measurements collected from the gyros, telescope, and SQUID (Superconducting Quantum Interference Device) magnetometer readouts, until the liquid helium in the Dewar was exhausted on September 25, 2005. (The helium actually lasted about three weeks longer than expected, allowing for extra calibration tests to be made.) Throughout 2006, the GP-B science team worked through a three-phase analysis of the data, to be concluded in early 2007 and to be announced formally in December 2007 after a careful and critical review by the GP-B external Science Advisory Committee (SAC), as well as by other international experts. During the latter part of 2006 and 2007, members of the GP-B team were also preparing a number of scientific and engineering papers for publication.

GP-B was arguably the most sophisticated spacecraft ever flown. It incorporated many new technologies most notably the gyros, their suspension systems, the accompanying SQUID readouts, and the precision-pointing of the spacecraft-fixed telescope all of whose debut performances in space occurred during this mission. GP-B is the first spacecraft ever to achieve nine degrees of freedom in control: The spacecraft itself maintained three degrees of freedom in attitude control (pitch, yaw, and roll), plus three degrees of freedom in translational drag-free control (front-to-back, side-to-side, and up-down). In addition, the Gyro Suspension System (GSS) for each gyro maintained three degrees of freedom in controlling the location of its spherical rotor within the gyro housing. The GP-B gyros, which performed extraordinarily well in orbit, have been listed in the Guinness Database of World Records as being the roundest objects ever manufactured. GP-B was actually the second dedicated NASA physics experiment to test aspects of General Relativity. The first, Gravity Probe A, was led in 1976 by Dr. Robert Vessot of the Smithsonian Astrophysical Observatory (SAO). GP-A compared elapsed time in three identical hydrogen maser clocks two on the ground and the third traveling for two hours in a rocket, and confirmed the Einstein Redshift prediction to 1.4 parts in 104.

MESSENGER

NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging), launched on August 3, 2004, aboard a Delta 2 rocket from Cape Canaveral Air Force Station, Florida, is scheduled to become the first spacecraft to orbit the planet Mercury, beginning in 2011. The approximately 1.2-ton (1,100-kilogram) spacecraft is in a solar orbit, a 4.9-billion mile (7.9-billion kilometer) journey that includes 15 trips around the sun. On August 2, 2005, MESSENGER returned to Earth for a gravity boost. Next, it flew past Venus in October 2006 and will do so again in June 2007, using the tug of Venus gravity to resize and rotate its trajectory closer to Mercury's orbit. Three Mercury flybys, each followed about two months later by a course correction maneuver, will put the spacecraft in position to enter Mercury orbit in March 2011. During the flybys - set for January 2008, October 2008 and September 2009 MESSENGER, the second spacecraft sent to Mercury after Mariner 10 flew past it three times in 1974-75 and gathered detailed data on less than half the surface, will map nearly the entire planet in color, image most of the areas unseen by Mariner 10 in 1974-75, and measure the composition of the surface, atmosphere and magnetosphere. Mariner 10 data were invaluable for planning MESSENGER's year-long orbital mission.

On October 24, 2006, MESSENGER came within 2,990 kilometers (1,860 miles) of the surface of Venus during its second planetary encounter, swinging by Venus at 4:34am EDT). About 18 minutes after the approach, an anticipated solar eclipse cut off communication between Earth and the spacecraft. Contact was reestablished at 10:15am through NASA's Deep Space Network, and the team collected data to assess MESSENGER's performance during the flyby.

Researchers are looking for answers to several crucial questions such as: Why is Mercury so dense? What is the geologic (rock) history of Mercury? And what is the structure of Mercury's core? MESSENGER is commissioned to investigate the answers to these and other important questions. It is the seventh mission selected for NASA's Discovery Program, the agency's innovative approach to low-cost, scientifically focused planetary missions. It was built for NASA by the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Swift

NASA's Swift satellite, launched on November 20, 2004 aboard a Delta 2 rocket from Cape Canaveral, was designed and built with international participation (England, Italy) to solve the 35-year-old mystery of the origin of gamma-ray bursts (GRBs). These flashes are brighter than a billion suns, yet last only a few milliseconds. They had been too fast for earlier instruments to catch. Scientists now believe the bursts, distant yet fleeting explosions, are related to the formation of black holes throughout the universe: the birth cries of black holes. In its first twelve months of operation researchers have discovered the farthest GRB ever seen, identified counterparts to short GRBs, discovered new GRBs at a rate of 100 per year, and explored a brand-new time interval in GRB light curves (which revealed the unpredicted phenomena of GRB flares and rapid X-ray afterglow declines). On July 5, 2006, the Swift observatory began observing supernova 2006dm a few days after its explosion. The supernova is the result of the thermonuclear explosion of a white dwarf in the galaxy MCG-01-60-21 which is located some 300 million lightyears from Earth. The galaxy is part of a loose group of galaxies which are gravitationally bound and have passed close to each other in the past. Remnants of such a recent nearby encounter are the faint bridges of stars and gas between the two brightest galaxies of this group. Also in 2006, exploding "star within a star"-X-ray observations by Swift of the outburst from RS Ophiuchi were reported at the National Astronomy Meeting in the UK. RS Oph is a binary system containing a white dwarf orbiting around a red giant star. An unusual burst, GRB 050801, in the distant Universe detected by Swift showed a bright afterglow with steady emission both in X-ray and optical wavelengths that lasted for 250 seconds after the end of the prompt gamma-ray emission, and occurred before the afterglow began its typical decline in brightness. Scientists have suggested that the end product of this GRB could have been a magnetar, rather than a black hole. Another discovery by Swift in 2006 were X-rays from a comet that is now passing the Earth and rapidly disintegrating on what could be its final orbit around the sun. On the technical side, the observatory and the instruments continue to work well. Through coordination of observations from several ground-based telescopes, Swift and other satellites, scientists solved the 35-year-old mystery of the origin on powerful split-second flashes of light called short GRBs. To track these mysterious bursts, Swift carries a suite of three main instruments: the Burst Alert Telescope (BAT), the X-Ray Telescope (XRT) and the UltraViolet/Optical Telescope (UVOT). Updated orbital lifetime predictions for Swift indicate that the observatory may remain in orbit up to 2022.

GALEX

GALEX (Galaxy Evolution Explorer), launched by NASA on April 28, 2003, on a Pegasus XL rocket from a L-1011 aircraft into a nearly circular Earth orbit, is an orbiting space telescope for observing tens of millions of star-forming galaxies in ultraviolet (UV) light across 10 billion years of cosmic history. Its telescope has a basic design similar to the Hubble Space Telescope (HST), but while HST views the sky in exquisite detail in a narrow field of view - like a grain of sand held at arm's length - GALEX is tailored to view hundreds of galaxies in each observation. Thus, it requires a large field of view, rather than high resolution, in order to efficiently perform the mission's surveys. During 2006, among else, GALEX caught a giant black hole red-handed dipping into a cosmic cookie jar of stars, the first time astronomers have seen the whole process of a black hole eating a star, from its first to nearly final bites. For perhaps thousands of years, the black hole rested quietly deep inside an unnamed elliptical galaxy. But then a star ventured a little too close to the sleeping black hole and was torn to shreds by the force of its gravity. Part of the shredded star swirled around the black hole, then began to plunge into it, triggering a bright ultraviolet flare that GALEX was able to detect. Supermassive black holes in some giant galaxies create such a hostile environment that they shut down the formation of new stars, according to GALEX findings published in the August 24 issue of Nature. The orbiting observatory surveyed more than 800 nearby elliptical galaxies of various sizes. An intriguing pattern emerged: the more massive, or bigger, the galaxy, the less likely it was to have young stars. Because bigger galaxies are known to have bigger black holes, astronomers believe the black holes are responsible for the lack of youthful stars.

Spitzer Space Telescope (SST)

Formerly known as SIRTF (Space Infrared Telescope Facility) and launched on August 24, 2003, the Spitzer Space Telescope is the fourth and final element in NASA's family of Great Observatories and represents an important scientific and technical bridge to NASA's Astronomical Search for Origins program. The Observatory carries an 85-cm cryogenic telescope and three cryogenically cooled science instruments capable of performing imaging and spectroscopy in the 3.6 to 160 micron range. Its supply of liquid helium for radiative-cryogenic cooling was estimated post-launch to last for about 5.8 years, assuming optimized operation. In 2006, among else, SST, with its powerful infrared (IR) vision, was able to unearth nearly 2,300 planet-forming disks in the Orion cloud complex, a collection of turbulent star-forming clouds that includes the well-known Orion nebula. The disks--made of gas and dust that whirl around young suns--are too small and distant to be seen by visible-light telescopes; however, the infrared glow of their warm dust is easily spotted by Spitzer's infrared detectors. Each disk has the potential to form planets and its own solar system. Astronomers have long scrutinized the vast and layered clouds of the Orion nebula, an industrious star-making factory visible to the naked eye in the sword of the famous hunter constellation. Other SST observations in 2006 strongly suggested that infrared light detected in a prior study originated from clumps of the very first objects of the Universe. The data indicate this patchy light is splattered across the entire sky and comes from clusters of bright, monstrous objects more than 13 billion light-years away. Astronomers believe the objects are either the first stars--humongous stars more than 1,000 times the mass of our sun--or voracious black holes that are consuming gas and spilling out tons of energy. If the objects are stars, then the observed clusters might be the first mini-galaxies containing a mass of less than about one million suns. The Milky Way galaxy holds the equivalent of approximately 100 billion suns and was probably created when mini-galaxies like these merged. Another Spitzer first in 2006 were the first measurements of the day and night temperatures of a planet outside our solar system. The IR observatory revealed that the Jupiter-like gas giant planet circling very close to its sun once every 4.6 days, Upsilon Andromedae, is always as hot as fire on one side and potentially as cold as ice on the other, a temperature difference of 2,550 degrees Fahrenheit. Upsilon Andromedae, about 40 light-years away and visible to the naked eye at night in the constellation Andromeda, is circled by two other known planets.

RHESSI

RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager, in honor of the late NASA scientist who pioneered the fields of solar-flare physics, gamma-ray astronomy and cosmic ray research), launched on February 5, 2002, in 2006 continued its operation in Earth orbit, providing advanced images and spectra to explore the basic physics of particle acceleration and explosive energy release in solar flares. Since its launch the spacecraft has been very successful observing solar flares, which are capable of releasing as much energy as a billion one-megaton nuclear bombs.

Hubble Space Telescope

Sixteen years after it was placed in orbit, the Hubble Space Telescope (HST) continued to probe far beyond the Solar System, producing imagery and data useful across a range of astronomical disciplines to expand our knowledge of the universe. The orbiting telescope has become one of the most important instruments in the history of astronomy. Hubble was and is making discoveries at a rate that is unprecedented for a single observatory, and its contributions to astronomy and cosmology are wide-ranging. In 2006, among else, HST captured an unprecedented look at the Orion Nebula. This turbulent star formation region is one of astronomy's most dramatic and photogenic celestial objects. In a mosaic containing a billion pixels, Hubble's ACS (Advanced Camera for Surveys) uncovered thousands of stars never seen before in visible light. Some are merely one-hundredth the brightness of previously viewed Orion stars. Scientists using Hubble discovered in 2006 that dark energy is not a new constituent of space, but rather has been present for most of the Universe's history. Dark Energy is a mysterious repulsive force that causes the Universe to expand at an increasing rate. Also in 2006, NASA approved another servicing mission to the Hubble by a space shuttle, the fifth, not only to ensure that HST can function for perhaps as much as another ten years, but also to increase its capabilities significantly in key areas. As part of the servicing and upgrade, two new scientific instruments will be installed: the Cosmic Origins Spectrograph (COS) and the Wide Field Camera 3 (WFC3). The shuttle mission, with a crew of six, is planned for 2008.

In 2006, design activities continued on the HST's successor, the James Webb Space Telescope (JWST), by a contracting team headed by Northrop Grumman Space Technology, selected in 2002. Plans are to launch the giant new cosmic telescope (5,400 kg/11,880 lbs) in 2011 on a European Ariane 5 toward the second Lagrangian point (L2), 1.5 million km (930,000 miles) beyond Earth's orbit on the Sun-Earth line, where effects of their light on its optics are minimized and gravitational pull is relatively well balanced.

Chandra Observatory

Launched on shuttle mission STS-93 on July 23, 1999, the massive (12,930 lbs/5,870 kg) Chandra X-ray Observatory uses a high-resolution camera, high-resolution mirrors and a charge-coupled detector (CCD) imaging spectrometer to observe X-rays of some of the most violent phenomena in the universe which cannot be seen by the Hubble's visual-range telescope. Throughout its seventh year of operation, Chandra continued to provide scientists with views of the high-energy universe never seen before which potentially revolutionize astronomical and cosmological concepts. After NASA formally extended the operational mission of Chandra from five years to 10 years in September 2001 (including the science grants that fund astronomers to analyze their data and publish their results), in 2006 Chandra astronomers found direct proof of the existence of dark matter in the Universe through a tremendous collision of two large clusters of galaxies which has wrenched apart dark matter and normal matter, the most energetic cosmic event, besides the Big Bang, which is known. In galaxy clusters, the normal matter is bound by the gravity of an even greater mass of dark matter, which is invisible and can only be detected through its gravity, without which the fast-moving galaxies and the hot gas would quickly fly apart. Also in 2006, scientists announced the X-ray detection of a proto supermassive binary black hole by Chandra. The two black holes have already been seen in radio images, and the new X-ray images provided unique evidence that these two black holes, located in the nearby galaxy cluster Abell 400, are in the process of forming a binary system; that is, they are gravitationally bound and orbit each other. Each black hole is located at the center of its respective host galaxy and the host galaxies appear to be merging. It is not, however, just the two host galaxies that are colliding - the whole cluster in which they live is merging into another neighboring galaxy cluster.

Cassini/Huygens

NASA's six-ton (5.4-metric-ton) spacecraft Cassini continued its epic 6.7-year, 3.2-billion-km journey to and inside the planetary system of Saturn. During 2006, the spacecraft remained in excellent health, returning stunning imagery from its continuing journey through the Saturnian system. Among else, Cassini discovered a new ring around the planet during a one-of-a-kind observation made possible by the longest solar occultation of the spacecraft's four-year mission that allowed Cassini to map the presence of microscopic particles that are not normally visible across the ring system. As a result, Cassini saw the entire inner Saturnian system in a new light. During a solar occultation the sun passed directly behind Saturn, and Cassini was in the shadow of Saturn while the rings were brilliantly backlit. Usually, an occultation lasts only about an hour, but this time it was a 12-hour marathon. The newly discovered ring is a tenuous feature, visible outside the brighter main rings of Saturn and inside the G and E rings, and coincides with the orbits of Saturn's moons Janus and Epimetheus. Scientists expected that meteoroid impacts on Janus and Epimetheus might kick particles off the moons' surfaces and inject them into Saturn orbit, but they were surprised that a well-defined ring structure exists at this location. Saturn's extensive, diffuse E ring, the outermost ring, had previously been imaged one small section at a time. The 12-hour marathon enabled scientists to see the entire structure in one view. The moon Enceladus is seen sweeping through the E ring, extending wispy, fingerlike projections into the ring. These very likely consist of tiny ice particles being ejected from Enceladus' south polar geysers, and entering the E-ring. Other spectacular sights captured by Cassini 's cameras include wispy fingers of icy material stretching out tens of thousands of kilometers from the active moon, Enceladus, and a cameo color appearance by planet Earth.

Also in 2006, Cassini has seen something never before seen on another planet: a hurricane-like storm at Saturn's south pole with a well-developed eye, ringed by towering clouds. The "hurricane" spans a dark area inside a thick, brighter ring of clouds. It is approximately 8,000 kilometers (5,000 miles) across, or two thirds the diameter of Earth. This giant Saturnian storm is apparently different from hurricanes on Earth because it is locked to the pole and does not drift around. Also, since Saturn is a gaseous planet, the storm forms without an ocean at its base. In the Cassini imagery, the eye looks dark at infrared wavelengths where methane gas absorbs the light and only the highest clouds are visible.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The spacecraft successfully entered orbit around Saturn on June 30, 2004. On December 25, 2004, ESA's Huygens probe detached from the Cassini orbiter to begin a three-week journey to Saturn's moon Titan. After 20 days and 4 million km cruise, the probe safely landed on Titan on January 14, 2005, becoming the first human-made object to explore on-site the unique environment of this moon, whose chemistry is assumed to be very similar to that of early Earth before life formed.

WMAP

NASA's Wilkinson Microwave Anisotropy Probe (formerly called the Microwave Anisotropy Mission, MAP), launched on June 30, 2001, on a Delta-2, is now located in an orbit around the second Lagrange libration point L2. Its differential radiometers measure, with unprecedented accuracy, the temperature fluctuations of the cosmic microwave background radiation (CMBR). The CMBR is the light left over from the Big Bang, bathing the whole Universe in this afterglow light. It is the oldest light in the Universe, having traveled across the cosmos for 14 billion years, and the patterns in this light across the sky encode a wealth of details about the history, shape, content, and ultimate fate of the Universe. Since start of WMAP operations, scientists produced the first version of a full sky map of the faint anisotropy or variations in the CMBR's temperature (now averaging a frigid 2.73 degrees above absolute zero). Results to date indicate that the Universe is 13.7 billion years old, with a margin of error of close to 1%, the first stars ignited 200 million years after the Big Bang, light gathered in revealing WMAP pictures is from 379,000 years after the Big Bang, and the Universe consists of 4% atoms, 23% cold dark matter and 73% dark energy. The data places new constraints on the dark energy, which now seems more like a "cosmological constant" than a negative-pressure energy field called "quintessence" (the latter however is not ruled out).

Scientists peering back to the oldest light in the universe have new evidence to support the concept of inflation. The concept poses the universe expanded many trillion times its size in less than a trillionth of a second at the outset of the big bang. This finding, made with WMAP in 2006, is based on three years of continuous observations of the CMBR. WMAP polarization data allow scientists to discriminate between competing models of inflation for the first time. This is a milestone in cosmology. Previous WMAP results focused on the temperature variations of this light, which provided an accurate age of the universe and insights into its geometry and composition. The new WMAP observations give not only a more detailed temperature map, but also the first full-sky map of the polarization of the CMB. This major breakthrough will enable scientists to obtain much deeper insight into what happened within the first trillionth of a second of the universe.

ACE

The Advanced Composition Explorer (ACE), launched on August 25, 1997, is positioned in a halo orbit around L1, where gravitational forces are in equilibrium. During 2006, ACE continued to observe, determine and compare the isotopic and elemental composition of several distinct samples of matter, including the solar corona, the interplanetary medium, the local interstellar medium and galactic matter. With a semi-major axis of approximately 200,000 km, its elliptical orbit affords ACE a prime view of the Sun and the galactic regions beyond, from a vantage point approximately 1/100th of the distance from the Earth to the Sun. A fuel use strategy has been implemented that will allow continued operations through the year 2022. By end-2006, ACE has been at the L1 point for almost 10 years, and the spacecraft and instruments are still working very well, with the exception of the SEPICA (Solar Energetic Particle Ionic Charge Analyzer) instrument. Due to failure of the valves that control gas flow through the instrument, active control of SEPICA's proportional counter is no longer possible. As of October 2006, 438 peer reviewed papers have been published by ACE science team members.

Stardust

In January 2006, NASA's comet probe Stardust returned safely to Earth. Launched on February 3, 1999 on a Delta 2, the probe passed by Comet P/Wild 2 on January 2, 2004, with a closest approach of about 150 km at a relative velocity of about 6.1 km/sec, at 1.85 AU (astronomical units) from the Sun and 2.6 AU from Earth, having weathered a strong sandblasting by cometary particles hurtling toward it at about six times the speed of a rifle bullet, collected particles and began its two-year, 1.14 billion kilometer (708 million mile) trek back to Earth. After the Wild flyby, the sample collector, deployed in late December 2003, was retracted, stowed, and sealed in the vault of the sample reentry capsule. On January 15, 2006, Stardust's sample return capsule deployed its drogue and main parachutes in the Earth's atmosphere, and at 2:10am Pacific time the capsule carrying cometary and interstellar particles successfully touched down in the desert salt flats of the U.S. Air Force Utah Test & Training Range.

Ulysses

In 2006, the joint European/NASA solar polar mission Ulysses celebrated its 16th launch anniversary. Carried into space on 6 October 1990 by the space shuttle Discovery (STS-41), the Ulysses spacecraft has already travelled an amazing 7 billion km and at this time is still going strong. On November 17, 2006, the spacecraft reached another important milestone on its epic out-of-ecliptic journey: the start of the third passage over the Sun's south pole. Ulysses is engaged in the exploration of the heliosphere, the bubble in space blown out by the solar wind. The first polar passes in 1994 (south) and 1995 (north) took place near solar minimum, whereas the second set occurred at the height of solar activity in 2000 and 2001. As Ulysses approached the polar regions for the third time, the Sun has settled down once again and was close to its minimum. Ulysses orbits the Sun once every 6.2 years, making it perfect for studying the 11-year solar activity cycle. Even though the Sun will be close to its activity minimum just as it was in 1994-95, there is one fundamental difference: the Sun's magnetic field has reversed its polarity. In addition to the 11-year activity cycle, the Sun has a magnetic cycle of 22 years, known as the Hale Cycle. Ulysses, now in its 17th year in orbit, is giving scientists the chance to observe the heliosphere from a unique, out-of-ecliptic vantage point and with the same set of instruments over almost a complete Hale Cycle. Ulysses carries a comprehensive suite of sophisticated scientific instruments, several of which are of a kind never flown in space before. In addition to enabling the mission's core business - providing the first survey of the solar wind in four dimensions (three spatial dimensions and time) - this combination has enabled scientists to make many groundbreaking discoveries, some in areas that were not even imagined when the mission was first planned. Ulysses firsts include: First direct measurements of interstellar dust and neutral helium gas, first measurements of rare cosmic-ray isotopes, first measurements of so-called pickup ions of both interstellar and near-Sun origin, first in-situ observations of comet tails at large distances from the Sun, and first observations of particles from solar storms over the solar poles.

Voyager

The Voyager missions, now in their 30th year, continue their quest to push the bounds of space exploration. The twin Voyager 1 & 2 spacecraft opened new vistas in space by greatly expanding our knowledge of Jupiter and Saturn. Voyager 2 then extended the planetary adventure when it flew by Uranus and Neptune, becoming the only spacecraft ever to visit these worlds. In 2006, Voyager 1, already the most distant human-made object in the cosmos, passed a major milestone when it surpassed the 100 astronomical units (AU) distance from the Sun (August 15), i.e., the spacecraft, which launched nearly three decades ago, was 100 times more distant from the sun than Earth is. At that time Voyager 1 was about 15 billion kilometers (9.3 billion miles) from the sun. Both Voyagers are still working, 24 hours a day, seven days a week. The spacecraft are now traveling at a distance where the sun is but a bright point of light and solar energy is not an option for electrical power. The Voyagers owe their longevity to their nuclear power sources, called radioisotope thermoelectric generators (RTGs). Voyager 1 is now at the outer edge of our solar system, in an area called the heliosheath, the zone where the sun's influence wanes. This region is the outer layer of the 'bubble' surrounding the sun, and no one knows how big this bubble actually is. Voyager 1 is literally venturing into the great unknown and is approaching interstellar space. Traveling at a speed of about one million miles per day, Voyager 1 could cross into interstellar space within the next 10 years. Close on the heels of its sister ship, Voyager 2 also continues the groundbreaking journey with the current mission to study the region in space where the Sun's influence ends and the dark recesses of interstellar space begin. Voyager 1 is escaping the solar system at a speed of about 3.6 AU per year and Voyager 2 is covering about 3.3 AU per year. Both spacecraft are expected to continue to operate and send back valuable data until at least the year 2020. The adventurers' current mission, the Voyager Interstellar Mission (VIM), will explore the outermost edge of the Sun's domain. And beyond.

Mars exploration

The main event in 2006 for NASA's Mars program was the arrival of yet another unmanned exploration probe, MRO, at the Red Planet, joining five other spacecraft currently studying Mars: Mars Express, Mars Odyssey, Mars Global Surveyor and two Mars Exploration Rovers. This is largest number of active spacecraft to study another planet in the history of space exploration.

Mars Reconnaissance Orbiter (MRO)

MRO is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit. The $720 million spacecraft was built by Lockheed Martin under the supervision of NASA's Jet Propulsion Laboratory (JPL). It was launched on August 12, 2005, on an Atlas V launch vehicle and arrived at Mars on March 10, 2006, after a 300 million-mile trip, taking more than 35 hours to circle the planet in its initial very elongated (elliptic) orbit for subsequent aerobraking maneuvers to achieve a lower circular orbit. During the final weeks of aerobraking, it was flying more than 10 orbits each day. After dipping into the upper fringes of the atmosphere 426 times to exert drag with its large solar arrays to lower the orbit, on September 11 MRO fired its six intermediate-size thrusters for 12.5 minutes, shifting the low point of its orbit to stay near the Martian south pole and the high point to stay near the north pole. The altitude of the final science orbit ranges from 155 miles (250 km) to 196 miles (316 km) above the surface. The main science investigations began in November. First results provided provocative new evidence of watery habitats on Mars eons ago. During its two-year science phase, the mission will return more data about Mars than all previous Mars missions combined. For that purpose, MRO contains a host of scientific instruments such as the High Resolution Imaging Science Experiment (HiRISE) camera, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), and the Shallow Subsurface Radar (SHARAD), which will be used to analyze the landforms, stratigraphy, minerals and ice of Mars. It will pave the way for future spacecraft by monitoring daily weather and surface conditions, studying potential landing sites, and testing a new telecommunications system. MRO will serve as a highly capable relay satellite for future missions.

Spirit (MER-A) & Opportunity (MER-B)

The six-wheeled rover vehicle Spirit, launched on June 10, 2003, on a Delta 2/Heavy rocket, landed on January 3. 2004 (ET) almost exactly at its intended landing site in Gusev Crater in excellent condition. Opportunity, NASA's second Mars explorer and twin to Spirit, launched on July 7, 2003 (ET), also on a Delta 2/Heavy after a cliffhanger countdown, touched down on January 25, 2004, right on target on Meridiani Planum, halfway around the planet from the Gusev Crater site of its twin, also in excellent condition. At end-2006, NASA's twin Mars rovers, nearing the third anniversary of their landings, were getting smarter as they get older. The unexpected longevity of Spirit and Opportunity is giving NASA a chance to field-test on Mars some new capabilities useful both to these missions and future rovers. Spirit began its fourth year on Mars on January 3, 2007, Opportunity on January 24. In addition to their continuing scientific observations, they are now testing four new skills included in revised flight software uploaded to their onboard computers. One of the new capabilities enables spacecraft to examine images and recognize certain types of features. It is based on software developed for NASA's Space Technology 6 "thinking spacecraft." Spirit has photographed dozens of dusty whirlwinds in action, and both rovers have photographed clouds. Until now, however, scientists on Earth have had to sift through many transmitted images from Mars to find those few. With the new intelligence boost, the rovers can recognize dust devils or clouds and select only the relevant parts of those images to send back to Earth. This increased efficiency will free up more communication time for additional scientific investigations. To recognize dust devils, the new software looks for changes from one image to the next, taken a few seconds apart, of the same field of view. To find clouds, it looks for non-uniform features in the portion of an image it recognizes as the sky. Another new feature, called "visual target tracking," enables a rover to keep recognizing a designated landscape feature as the rover moves. Visual target tracking can be combined with a third new feature -- autonomy in calculating where it is safe to reach out with the contact tools on the rover's robotic arm. The combination gives Spirit and Opportunity a capability called "go and touch," which was yet to be tested on Mars. So far in the mission, whenever a rover has driven to a new location, the crew on Earth has had to evaluate images of the new location to decide where the rover could place its contact instruments on a subsequent day. After the new software has been tested and validated, the crew will have the option of letting a rover choose an arm target for itself the same day it drives to a new location.

By end-2006, Spirit and Opportunity have worked on Mars for nearly 12 times as long as their originally planned prime missions of 90 Martian days. Spirit has driven about 4.3 miles (6.9 km), Opportunity has driven about 6.1 miles (9.8 km). Spirit has returned more than 88,500 images, Opportunity more than 80,700.

Opportunity 's key discovery since landing has been mineral and rock-texture evidence that water drenched and flowed over the surface in at least one region of Mars long ago. Spirit has found evidence that water in some form has altered mineral composition of some soils and rocks in older hills above the plain where the rover landed. Among the rovers' many other accomplishments: (1) Opportunity has analyzed a series of exposed rock layers recording changing environmental conditions from the times when the layers were deposited and later modified. Wind-blown dunes came and went. The water table fluctuated; (2) Spirit has recorded dust devils forming and moving, events which were made into movie clips. These provide new insight into the interaction of Mars' atmosphere and surface; (3) both rovers have found metallic meteorites on Mars. Opportunity found one rock with a composition similar to a meteorite that reached Earth from Mars.

After Spirit and Opportunity, NASA's next-generation Mars mission, to be launched in mid-2007, is the Phoenix Mars Lander, followed by the next rover, the Mars Science Laboratory, currently in development for launch in 2009.

Mars Odyssey

NASA's Mars Odyssey probe, launched April 7, 2001, reached Mars on October 24, 2001, after a six-month and 286-million mile journey. Entering a highly elliptical orbit around the poles of the Red Planet, it began to change orbit parameters by aerobraking, reducing its ellipticity to a circular orbit at 400 km by end of January 2002. The orbiter is circling Mars for at least three years, with the objective of conducting a detailed mineralogical analysis of the planet's surface from space and measuring the radiation environment. On August 25, 2004, the Odyssey orbiter began working overtime after completing a prime mission that discovered vast supplies of frozen water, ran a safety check for future astronauts, and mapped surface textures and minerals all over Mars, among other feats. Odyssey's camera system obtained the most detailed complete global maps of Mars ever, with daytime and nighttime infrared images at a resolution of 100 meters (328 feet). The spacecraft, which has been examining Mars in detail since February 2002 (more than a full Mars year of about 23 Earth months) has been approved for a second extended mission into 2007. At end-2005, a new view of the biggest canyon in the solar system, composed of hundreds of photos from the Mars Odyssey orbiter, offered scientists and the public an online resource for exploring the entire canyon in detail. This canyon system, named Valles Marineris, stretches as far as the distance from California to New York. Steep walls nearly as high as Mount Everest give way to numerous side canyons, possibly carved by water. In places, walls have shed massive landslides spilling far out onto the canyon floor. In 2006, imaging experts at the Jet Propulsion Laboratory (JPL) combined hundreds of images taken via the orbiter to create a high-resolution, simulated video ride through the Grand Canyon of the solar system, Valles Marineris on Mars, also known as the Mariner Valley, which takes viewers on a journey through this vast canyon system on an imaginary scout ship that dives low over landslides and races through winding canyons. Stretching for 3,000 miles, this canyon system slices across the Red Planet near its equator, 10 times longer and deeper than Arizona's Grand Canyon, and 20 times wider, featuring steep walls nearly as high as Mount Everest that give way to numerous side canyons, possibly carved by water.  In places, walls have shed massive landslides spilling far out onto the canyon floor.

Mars Global Surveyor (MGS)

MGS completed its primary mission at the end of January 2001 and entered an extended mission. The spacecraft has returned more data about the Red Planet than all other missions combined. After its arrival at Mars on September 11, 1997, MGS started a long series of aerobrake passes around the planet and, after reaching its operational orbit early in 1999, began its mapping mission on March 9. In 2001, it sent back its 100,000th image of the Martian surface and, in tandem with the Hubble Space Telescope, had a ringside seat to the largest global dust storm on the Martian surface seen in decades. MGS has been transmitting a steady stream of high-resolution images, which showed that the Red Planet is a world constantly being reshaped by forces of nature including shifting sand dunes, monster dust devils, wind storms, frosts and polar ice caps that grow and retreat with the seasons. In September 2004, MGS started its third mission extension after seven years of orbiting Mars, using an innovative technique to capture pictures even sharper than most of the more than 170,000 it has already produced. One dramatic example from the spacecraft's Mars Orbiter Camera (MOC) showed actual wheel tracks of the Mars Exploration Rover Spirit and the rover itself. In 2005, MGS also took the first pictures of any spacecraft orbiting Mars ever taken by another spacecraft orbiting Mars: Mars Express was passing about 155 miles away when the MGS MOC photographed it on April 20. The next day, the camera caught Mars Odyssey passing 56 to 84 miles away. All three spacecraft were moving at almost 7,000 miles per hour, and at 62 miles distance the field-of-view of the MOC is only 830 yards across. On November 2, 2006, after studying Mars four times as long as originally planned, Mars Global Surveyor succumbed to battery failure caused by a complex sequence of events involving the onboard computer memory and ground commands. On that day, after the orbiter was ordered to perform a routine adjustment of its solar panels, MGS reported a series of alarms, but indicated that it had stabilized. That was its final transmission. Subsequently, the spacecraft reoriented to an angle that exposed one of two batteries carried on the spacecraft to direct sunlight. This caused the battery to overheat and ultimately led to the depletion of both batteries. Within 11 hours, empty batteries likely left the spacecraft unable to control its orientation, resulting in a significant loss to Mars exploration.

Earth Science

In 2006, NASA launched three Earth science satellites, two more than in 2005,- CloudSat, CALIPSO, and GOES-N, as the NASA-centered international Earth Observing System (EOS) continues to operate, with Aqua as the first member of a group of satellites termed the Afternoon Constellation (or sometimes the A-Train). The second member launched in 2004 was Aura, the third member was PARASOL, in December 2004, and the fourth and fifth members were CloudSat and CALIPSO, launched in 2006. Expected upcoming missions are OCO and Glory, with the placement of Glory not yet determined. Once completed, the A-Train will be led by OCO, followed by Aqua, then CloudSat, CALIPSO, PARASOL, and, in the rear, Aura.

CloudSat

CloudSat is an experimental mission designed to study the effects of clouds on climate and weather with capabilities 1,000 times more sensitive than typical weather radar, using millimeter-wavelength radar to measure the altitude and properties of clouds. This information is providing the first global measurements of cloud properties that will help scientists compile a database of cloud measurements, aiding in global climate and weather prediction models. The 2202-lb (999-kg) CloudSat was launched with the CALIPSO satellite by a Delta 2 from VAFB on April 28 into a polar orbit at an altitude of 438 miles (705 km). Both spacecraft are part of a constellation of spacecraft called the "A-Train," including Aqua, Aura and PARASOL, dedicated to studying the Earth's weather and environment, with CloudSat orbiting approximately one minute behind Aqua. The mission is a joint program of NASA and the Canadian Space Agency (CSA).

CALIPSO

Highly complementary with CloudSat, the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite is providing new insight into the role that clouds and atmospheric aerosols (airborne particles) play in regulating Earth's weather, climate, and air quality. CALIPSO was launched into orbit around the Earth along with CloudSat as part of the "A-train," a constellation of Earth observing satellites. CALIPSO provides the next generation of climate observations, including an advanced study of clouds and aerosols, drastically improving our ability to predict climate change and to study the air we breathe. Its payload includes three co-aligned nadir-viewing instruments: (1) the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP, pronounced the same as calliope) to provide vertical profiles of aerosol and cloud backscatter and depolarization; (2) an Imaging Infrared Radiometer (IIR) with three channels in the infrared window region optimized for retrievals of cirrus particle size; and (3) the Wide Field Camera (WFC), a moderate spatial resolution imager with one visible channel which provides meteorological context and a means to accurately register CALIPSO observations to those from MODIS on the Aqua satellite. These instruments are designed to operate autonomously and continuously, although the WFC acquires data only under daylight conditions. Science Data are downlinked using an X-band transmitter system which is part of the payload. The mission is a joint program of the U.S. (NASA) and France (Centre National d'Etudes Spatiales/CNES).

GOES-N

The National Oceanic and Atmospheric Administration (NOAA)/NASA joint mission GOES-N lifted off aboard a Delta 4 rocket from CCAFS, Florida, on May 24 (6:11pm EDT). After reaching its geosynchronous orbit of approximately 22,300 miles and a successful post-launch checkout, the satellite was placed in on-orbit storage mode where it will be able to more rapidly replace a failure of any existing operational GOES (Geostationary Operational Environmental Satellites). Later, GOES-N is aimed at becoming the primary U.S. hurricane-monitoring spacecraft. GOES-N, to be renamed GOES-13, is the latest in a series of Earth monitoring satellites which provide the kind of continuous monitoring necessary for intensive data analysis. Being in a geostationary orbit allows GOES to hover continuously over one position on the Earth's surface, appearing stationary. As a result, GOES provide a constant vigil for the atmospheric "triggers" for severe weather conditions such as tornadoes, flash floods, hail storms, and hurricanes.

NOAA-18

After its launch on May 20, 2005, on a Boeing Delta 2 expendable rocket, the NOAA-18 environmental satellite for NOAA in 2006 continued to operate in excellent condition, circling the Earth in a polar orbit of 870 km (544 s.mi.) altitude and 98.73 degrees inclination. With the objective to improve weather forecasting and monitor environmental events around the world, NOAA-18 is collecting data about the Earth's surface and atmosphere. The data are input to NOAA's long-range climate and seasonal outlooks, including forecasts for El Ni'o and La Ni'a. NOAA-18 is the fourth in a series of five Polar-orbiting Operational Environmental Satellites (POES) with instruments that provide improved imaging and sounding capabilities. NOAA-18 has instruments used in the 1982-established international Search and Rescue Satellite-Aided Tracking System, called COSPAS-SARSAT. NOAA polar-orbiting satellites detect emergency beacon distress signals and relay their location to ground stations, so rescue can be dispatched. In 2006 alone, SARSAT was credited with rescuing 272 people in 105 incidents in the U.S.

Aura

Aura (Latin for breeze), launched from Vandenberg AFB on July 15, 2004, on a Delta 2 rocket, is NASA's third major Earth Observing System (EOS) platform, joining its sister satellites Terra and Aqua, to provide global data on the state of the atmosphere, land, and oceans, as well as their interactions with solar radiation and each other. Aura's design life is five years with an operational goal of six years. The satellite flies in formation about 15 minutes behind Aqua. During 2006, scientists used Aura and other satellites for tracking different chemicals present in Earth's atmosphere. These data are giving researchers a more complete picture of the causes and effects of atmospheric pollution. The scientists combined atmospheric models with actual measurements of ozone, carbon monoxide and nitrogen dioxide in Earth's lower atmosphere. This combination technique led to a surprising result: the amount of biomass burning in sub-equatorial Africa and the Indonesia/Australia region was underestimated, by a factor of between two and three. The new combination technique also enabled the researchers to link the observed biomass burning to ozone that was later formed over and downwind of these regions. In addition, Aura data showed that in 2006 the ozone hole in the polar region of the Southern Hemisphere has broken records for area and depth. The ozone layer acts to protect life on Earth by blocking harmful ultraviolet rays from the sun. The "ozone hole" is a severe depletion of the ozone layer high above Antarctica. It is primarily caused by human-produced compounds that release chlorine and bromine gases in the stratosphere. The Ozone Monitoring Instrument on NASA's Aura satellite measures the total amount of ozone from the ground to the upper atmosphere over the entire Antarctic continent.

ICESat

ICESat (Ice, Cloud, and land Elevation Satellite), also an Earth Observing System (EOS) spacecraft, is the benchmark mission for measuring ice sheet mass balance, cloud and aerosol heights, as well as land topography and vegetation characteristics. Launched on January 12, 2003, on a Delta 2 Expendable Launch Vehicle (ELV) into a near polar orbit at an altitude of 600 km with an inclination of 94 degrees, the spacecraft carries only one instrument,- the Geoscience Laser Altimeter System (GLAS). Scientists trying to understand the dynamics of the Earth are using the lasers of ICESat to measure the height of ice sheets, glaciers, forests, rivers, clouds and atmospheric pollutants from space with unprecedented accuracy, providing a new way of understanding our changing planet. GLAS sends short pulses of green and infrared light though the sky 40 times a second, all over the globe, and collects the reflected laser light with a one-meter telescope, yielding elevations. It also fires a fine laser beam of light that spreads out as it approaches the Earth surface to about 65 meters in diameter. On its way to the surface, those photons or particles of light bounce off clouds, aerosols, ice, leaves, ocean, land and more providing detailed information on the vertical structure of the earth system. In 2005, the ICESat mission and the GLAS instrument passed an important milestone when it reached 1,000,000,000 (1 billion) measurements while in orbit. The previous maximum measurements reached in space was approximately 670,000,000 which were emitted by the MOLA-2 Laser onboard the Mars Global Surveyor mission. In 2006, NASA continued collecting measurements from ICESat for developing a comprehensive ice sheet survey of the polar ice caps. The most comprehensive survey ever undertaken to date of the massive ice sheets covering both Greenland and Antarctica confirmed that climate warming is changing how much water remains locked in Earth's largest storehouse of ice and snow. Other recent studies have shown increasing losses of ice in parts of these sheets. This new survey was the first to inventory the losses of ice and the addition of new snow on both in a consistent and comprehensive way throughout an entire decade. It documented for the first time extensive thinning of the West Antarctic ice shelves and an increase in snowfall in the interior of Greenland, as well as thinning at the edges. All are signs of a warming climate predicted by computer models.

Aqua

Launched in May 2002, the 1750 kg (3858 lb) NASA satellite Aqua, formerly named EOS PM (signifying its afternoon equatorial crossing time), carrying six instruments weighing 1082 kg (2385 lb) designed to collect information on water-related activities worldwide, has been circling Earth in a polar, sun-synchronous orbit of 438 miles (705 km) altitude. During its six-year mission, Aqua is observing changes in ocean circulation and studies how clouds and surface water processes affect our climate. NASA and NOAA scientists, working with experimental data from Aqua's Atmospheric Infrared Sounder, a high-spectral resolution infrared instrument that takes 3-D pictures of atmospheric temperatures, water vapor and trace gases, are conducting research on improving the accuracy of medium-range weather forecasts in the Northern Hemisphere. Incorporating the instrument's data into numerical weather prediction models improves the accuracy range of experimental six-day Northern Hemisphere weather forecasts by up to six hours, a four-percent increase. These data have now been officially incorporated into the NOAA National Weather Service operational weather forecasts.

POES-M (NOAA-M)

The operational weather satellite POES-M (Polar-orbiting Operational Environmental Satellites-M) was launched from VAFB on a commercial Titan 2 rocket on June 24, 2002. The satellite, later renamed NOAA-M, is part of the POES program, a cooperative effort between NASA and NOAA, the United Kingdom (UK), and France. It joined the GOES-M launched in July 2001. Both satellites, operated by NOAA, continue to provide global coverage of numerous atmospheric and surface parameters for weather forecasting and meteorological research. NOAA-M broadcasts data directly to thousands of users around the world, using its environmental monitoring instruments for imaging and measurement of the Earth's atmosphere, its surface, and cloud cover. Observations include information about Earth radiation, sea and land surface temperature, atmospheric vertical temperature, water vapor, and ozone profiles in the troposphere and stratosphere.

GRACE

Launched on March 17, 2002, on a Russian Rockot carrier, the twin satellites GRACE (Gravity Recovery and Climate Experiment), named "Tom" and "Jerry", in 2006 continued to map the Earth's gravity fields by taking accurate measurements of the distance between the two satellites, using Global Positioning System (GPS) and a microwave ranging system. This allows making detailed measurements of Earth's gravity field, which will lead to discoveries about gravity and Earth's natural systems with possibly far-reaching benefits to society and the world's population. Among other things, GRACE in its almost five years of operation may have found a crater deep under the Antarctic ice that may mark an asteroid impact greater than the one that doomed the dinosaurs, measured the seafloor displacement that triggered the tsunami of 2004, and quantified changes in subsurface water in the Amazon and Congo river basins. GRACE provides scientists from all over the world with an efficient and cost-effective way to chart the Earth's gravity fields with unprecedented accuracy, yielding crucial information about the distribution and flow of mass within the Earth and its surroundings. The science data from GRACE consist of the inter-satellite range change measurements, and the accelerometer, GPS and attitude measurements from each satellite. In December 2005, the twin GRACE satellites have exchanged positions, and GRACE-1 became the trailing satellite. The swap was done to mitigate the risk of loss of thermal control over the K-band antenna horn (and subsequent spurious K-band range signal) due to atomic oxygen exposure. After the two satellites switched position, a special data collection campaign for the inter-satellite separation between about 70 km and about 170 km got underway. The mean inter-satellite separation is usually bound between 170 and 270 km, but the closer mean separation is expected to enhance the high-frequency signal content in the K-band range measurements. In 2006, data from the GRACE satellites in the first-ever gravity survey of the entire Antarctic ice sheet showed that the sheet's mass decreased significantly from 2002 to 2005. The project is a joint partnership between NASA and the German DLR (Deutsches Zentrum fr Luft- und Raumfahrt).

TOPEX/Poseidon

In early 2006, the joint US (NASA)/France (CNES) TOPEX/Poseidon oceanography satellite ceased operations after nearly 62,000 orbits of Earth. The spacecraft, launched August 10, 1992, lost its ability to maneuver, bringing to a close a successful 13-year mission. TOPEX/Poseidon revolutionized the study of Earth's oceans, providing the first continuous global coverage of ocean surface topography and allowing us to see important week-to-week ocean variations. Its data have helped in hurricane and El Ni'o/La Ni'a forecasting, ocean and climate research, ship routing, offshore industries, fisheries management, marine mammals research, modernizing global tide models and ocean debris tracking.

Department of Defense space activities

United States military space organizations continued their efforts to make space a routine part of military operations across all service lines. One focus concerns plans for shifting the advanced technology base toward space in order to continue building a new foundation for more integrated air and space operations in the 21st century as space is becoming increasingly dominant in military reconnaissance, communications, warning, navigation, missile defense and weather-related areas. The increased use of satellites for communications, observations, and through the GPS navigation and high-precision weapons targeting was and is of decisive importance for the military command structure. During the Afghanistan and Iraq conflicts and thereafter, orbiting assets ably demonstrated that space-based intelligence, surveillance, communications, weather, missile warning and navigation tools give commanders great advantages and leverage for each of the military services.

In 2006, Operationally Responsive Space (ORS), the new military vision of space as an integral part of national defense to provide operational capabilities, flexibility, and responsiveness that does not exist today, continued to evolve as U.S. Congress called for the establishment of an Office of ORS under the Dept. of Defense Executive Agent for Space. AFRL (Air Force Research Laboratory) Space Vehicles Directorate extended the Experimental Satellite System 11 (XSS-11) mission, launched in April 2005, an additional six months to continue on-orbit demonstration activities(XSS is a new class of low-cost satellites referred to as micro-satellites weighing less than 100 kilograms). Highlights of military space in 2006 included the launch of the first Delta 4 from California (VAFB/Vandenberg Air Force Base). There were seven military space launches (2005: 6; 2004: 5; 2003: 11), carrying nine payloads: two heavy Boeing Delta 4M vehicles, one with a DMSP Block SD-3 weather satellite of the Defense Meteorological Satellites Program, the other with a classified satellite, NROL-22, of the National Reconnaissance Office from VAFB into a polar orbit, four Boeing Delta 2 launchers, carrying two new GPS IIR-15 (M) navigation satellites (with dual civilian channel capability), three technology test satellites (USA-187, USA-188, USA-189), another classified NRO satellite (NROL-21), and one OSC Minotaur launcher with a tactical satellite (TACSAT-2).

Commercial space activities

In 2006, commercial space activities in the United States rose over the downturn of the prior years which came in the wake of the slump in the communications space market caused by failures of satellite constellations for mobile telephony in 2001/2002 and a slight recovery in 2003.

Some difficulties remained due to the export restrictions imposed to the US industry on sensitive technologies, but in general, commercial ventures gained a significantly larger role in US space activities. Commercial satellite launches consisted primarily of large communications satellite deliveries. Of the 23 total launch attempts by the United States in 2006 (16 in 2005, 19 in 2004, 26 in 2003), eight (44%) were commercial missions (NASA: 8; military: 7). In the launch services area, commercial missions consisted of one Atlas 5/Centaur by ILS/Lockheed Martin with the Astra 1KR comsat, and one Orbital Sciences Co. (OSC) Minotaur vehicle carrying six small Formosat-3 science satellites (FM1-6). The partnership of Boeing, RSC-Energia (Russia, 25% share), NPO Yushnoye (Ukraine) and Kvaerner Group (Norway) successfully launched five Russian Zenit 3SL (SeaLaunch) rockets carrying the Echostar 10, JSAT-9, Galaxy 16, Koreasat 5 and XM Radio 4 (XM-Blues) comsats from the Odyssey sea launch platform floating at the Equator (first launch 1999). The newcomer SpaceX conducted the maiden flight of its new Falcon 1 launch vehicle on March 24, but the launch failed when the main engine shut down prematurely. The military TACSAT-1 is scheduled for launch on Falcon 1 after the rocket's return to flight.