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SPACE FLIGHT 1999 - United States Space Activities

The four reusable shuttle vehicles of the U.S. Space Transportation System (STS) continued carrying people and payloads to and from Earth orbit for science, technology, operational research, systems maintenance and station logistics, accomplishing several difficult and important missions during the year. After having moved into actual orbital assembly in the preceding year, with First Element Launch (FEL) in November and the link-up of the first with the second building-block, the International Space Station (ISS) program moved forward on its schedule with further development steps.

The U.S. space program also suffered a sad loss in 1999 when former Gemini and Apollo astronaut Charles P. "Pete" Conrad died on July 8 of injuries sustained during a motorcycle accident. Conrad, a Navy test pilot and instructor, joined NASA as an astronaut in 1962 and flew his first mission on Gemini 5 in August 1965, completing 120 Earth orbits in eight days. The following September, he commanded the Gemini 11 mission, setting a new altitude record of almost 1360 km (850 miles) above the Earth. In 1969, he became the third man to walk on the moon as commander of the Apollo 12 mission, and in 1973 he flew into space for the last time, as the commander of the first crew to live and work on the experimental space station Skylab.

Also during 1999, NASA issued a request for proposals (RFP) for a launch services contract that would be worth more than $5 billion to winning contractors. It covers a broad range of planned NASA expendable launch vehicle needs across light, medium and heavy payloads. Awards were expected to be made by mid-2000.

The Mercury capsule "Liberty Bell 7", Astronaut Gus Grissom's spacecraft which sank about 145 miles (230 km) east-northeast of the Bahamas in the Atlantic Ocean in 1961 at the conclusion of the suborbital Mercury 4 mission, was successfully recovered on 7/21 from a depth of 16,000 ft. (4875 m), 38 years to the day after it was lost.

Space Shuttle

During 1999, NASA successfully completed three space shuttle missions, three less than in the preceding year. Launch of the first mission, STS-96, occurred in May, followed by STS-93in July and STS-103 in December, bringing the total number of shuttles launched since program inception to 96. For the human space flight program, the year was particularly significant in that the first of the three shuttle missions involved the first human visit and supply flight to the ISS.

STS-96. First crew visit in history to the International Space Station ISS. After an exact on-time liftoff on 5/27 (6:50am EDT) at the opening of a 9-minute launch window, Discovery docked flawlessly to the Unity/Zarya complex on 5/29 (12:24am) and was solidly mated at 12:39 over the Russia-Kazakhstan border. The crew, Commander Kent V. Rominger, Pilot Rick D. Husband, and Mission Specialists Tamara E. Jernigan, Ellen Ochoa, Daniel T. Barry, Julie Payette, and Valery Tokarev, represented three ISS partners, US, Canada (Payette), and Russia (Tokarev), and included three women (Jernigan, Ochoa, Payette). After undocking from the ISS on 6/3 (6:39am) and releasing the student satellite STARSHINE on 6/5 (3:10am), Discovery returned to KSC on 6/6 with a flawless landing (at 2:03am) after a 4 million mile (6.4 million km) trip in only the 11th night landing of the Shuttle program.

STS-93. Launch of the $1.5 billion Advanced X-Ray Astronomy Facility (AXAF), now called Chandra X-Ray Observatory, the third in NASA's series of "Great Observatories" on Columbia, on 7/23 (12:31am EDT), after two earlier launch attempts, scrubbed due to hazardous hydrogen concentration measured (erroneously) in the engine compartment (on 7/20) and unfavorable weather (on 7/22). Crewed by Eileen M. Collins, Jeffrey S. Ashby, Catherine G. Coleman, Steven A. Hawley and Michel Tognini, the shuttle's ascent to orbit proceeded nominally, despite a short-induced dropout of the main control computers on two Shuttle main engines, and a small hydrogen leak in one of the engine exhaust nozzles. The flight crew, under NASA's first woman commander (Collins) included a French mission specialist (Tognini). The observatory was successfully deployed by Coleman 7h 16m after launch and subsequently boosted itself to a final orbit of 86,992 by 6034 miles (139,188 by 9655 km), with a period of 63h 28m. Secondary objectives included firing of Columbia's jet thrusters at various times during the flight to help an Air Force satellite gather data on the characteristics of jet plumes in space. Also, Hawley and Tognini operated the SWUIS (Southwest Ultraviolet Imaging System) from a side hatch window, collecting data on ultraviolet light originating from a variety of planetary bodies. Ashby, Hawley and Tognini assessed an exercise system planned for the ISS, the TVIS (Treadmill Vibration Isolation and Stabilization) system, and the crew performed a number of additional experiments before returning to Earth on 7/27, landing at KSC at 11:20pm.

STS-103. Discovery lifted off on 12/19 (7:50pm EST) after several launch delays, to preform the third maintenance/repair mission to the Hubble Space Telescope (HST), with Curtis L. Brown as Commander, Scott J. Kelly as Pilot, and Mission Specialists Steven L. Smith, Jean-Francois Clervoy (ESA), John M. Grunsfeld, Michael Foale, and Claude Nicollier (ESA). The mission, originally planned for mid-2000, became necessary when the HST had to be put in "safe" (dormant) mode on 11/13/99 with only two of its six gyroscopes still functioning. HST capture occurred on 12/21 (7:34 pm), followed by berthing in the Shuttle cargo bay at 8:43pm. On 12/22, Smith and Grunsfeld, in a spacewalk of 8h15m, the second longest EVA in Shuttle history (after STS-49 in 1992, of 8h29m), installed six new gyros and six voltage/temperature improvement kits. During a second EVA, on 12/23, lasting 8h10m, Foale and Nicollier replaced the HST's main computer and 500 lbs. (227 kg) Fine Guidance Sensor. On 12/24, Smith and Grunsfeld spent 8h08m on a third EVA, replacing a radio transmitter and installing a new digital recorder as well as new insulation on two HST equipment bay doors. When the fully restored telescope was released into space on 12/25 (6:03pm), astronauts had conducted a total of 13 EVAs on the Hubble since its launch, amounting to 93h13m. Discovery returned to Earth on 12/27, landing at 7:01pm EST, the 20th landing at KSC in a row and the 13th night landing in Shuttle history.

Advanced Transportation Systems Activities

In the three-year-old NASA/industry cooperative effort to develop a reusable space launch vehicle to eventually take over launchings for a fraction of today's cost of space transportation (around $10,000 per pound of mass to orbit) with turnaround ratesconsiderably lower than those of the space shuttle, work is continuing at Lockheed Martin on the development of the X-33 as a technology demonstrator for a Single-Stage-to-Orbit (SSTO) Reusable Launch Vehicle (RLV). During 1999, most manufacturing for the X-33 was completed, and assembly was getting underway for a rollout of the demonstrator vehicle originally envisioned in January 2000 and first flight in July of that year. However, structural weaknesses in the advanced solid-graphite composite liquid-hydrogen tank, which resulted in structural failure of the tank's outer skin during a pressure test with cryogenic loading on 11/3, caused a major setback for the program, delaying it by perhaps several years.


Also part of the RLV program is the smaller air-launched X-34, being built by Orbital Sciences Corp. (OCS), which will test reusable launch vehicle (RLV) technologies. X-34flights began on 6/29 with the first of several captive-carry flights of the vehicle under the belly of an L1011 aircraft. Also during 1999, key rocket engine tests continued on the revolutionary propulsion systems for the winged booster testbeds, the 60,000 lbs. thrust liquid oxygen (LOX)/kerosene Fastrac engine for X-34, and the 500,000 lbs. XRS-2200 LOX/liquid hydrogen linear aerospike engine for the X-33.

NASA is also developing the X-43 as part of the Hyper-X program which bridges aircraft-type vehicles and space launch vehicles. Its goal is to demonstrate hydrogen-powered, air-breathing propulsion systems that could ultimately be applied in vehicles from hypersonic (speeds higher than Mach 5, i.e. five times the speed of sound) aircraft to reusable space launchers. In 1999, the first of three experimental vehicles, designated X-43A, arrived at NASA's Dryden Flight Research Center in California to prepare for flight in mid-2000. The 12-ft. (3.6 m)-long, unpiloted, non-rocket-propelled X-43 vehicles are powered by supersonic combustion ramjets ("scramjets") after having been accelerated by a Pegasus booster rocket airlaunched from a B-52 airplane. At least three flight tests are planned -- two at Mach 7 and one at Mach 10.

Specifically for the ISS, NASA is also developing a Crew Return Vehicle (CRV) to eventually take over the emergency lifeboat function for the space station from the currently chosen Russian Soyuz three-seater capsules. CRV willrequire a shirtsleeve environment for seven crewmembers in reclined couches, standard-sized for 95% of all U.S. males. It must have a minimum lifetime of one year attached to the ISS, with a possible extension to three years, must be capable of supporting medical equipment, carrying out a 9-hr. orbital free-flight mission and allowing access for a medical officer to an injured or ill crew member during such a mission. In 1999, NASA continued with full-scale flight testing of the X-38, the prototype test vehicle for the CRV, by dropping it from a B-52 at 23,000 ft (7000 m) altitude. Purpose of the tests with the first prototype, V-313, was to study the latter stages of the CRV's mission, when it transitions from subsonic lifting body flight to descent and landing under a large parafoil.

Space Sciences and Astronomy

In 1999, the U.S. launched 11 civil science spacecraft, up three from the previous year. This growth has become a trend because since 1995 NASA has markedly increased the number of civil satellites it develops and launches. The main reason and guiding force behind this trend is the switch in development strategy, shortly after the loss, in August 1993, of the Mars Observer, from large, expensive satellites to smaller and more numerous ones. Such new probe classes as Discovery, New Millennium, Small Explorer, and Medium Explorer will produce over 20 civil satellites during the next few years.

As in the previous year, in 1999 several automated and remotely-controlled research and exploration missions continued to add a remarkable range of significant and, in part, revolutionary discoveries to our growing body of knowledge about the universe.

Hubble Space Telescope. Nine years after it was placed in orbit, the Hubble Space Telescope (HST) continues to probe far beyond the Solar System, producing imagery and data useful across a range of astronomical disciplines.

The resulting data, in 1999, were used in one of the space telescope's most important projects to date - to determine more accurately the expansion rate of the universe and to give astronomers an extragalactic distance scale for their measurements. Using the unmatched resolution and photometry of the HST, astronomers reduced the uncertainties of the Hubble Constant that tells how rapidly the universe is expanding, by measuring the change in relative velocity of astronomical objects with distance, based on the Big Bang theory. The new estimate of the age of the cosmos is 12-13.5 billion years, and the reduction in uncertainty also showed that the universe will not collapse due to gravity but continue to expand indefinitely.

Among the stunning images from the HST are supermassive star clouds in the center of our Milky Way galaxy which give new clues of how stellar clusters are born, pictures of differing evolutionary paths of galaxies by peering deep inside the centers of star clusters and galaxies to resolve structures, bulges and bars of bright stars, the unusual bipolar shape of the Butterfly Nebula in the Large Magellanic Cloud, seen for the first time, and a dying star in the process of turning from a normal red giant into a planetary nebula, indicative of the likely future of our own Sun. Closer to Earth, Hubble's Wide Field and Planetary Camera, between April 27 and May 6, took pictures of the entire planet Mars, as it rotated, when it was only 87 million kilometers from Earth, the closest it has been in eight years.

When problems developed with the telescope's critical attitude control gyroscopes, leaving only two of its six gyros functioning and temporarily disabling the 12.5 ton, $3 billion facility, which went into a dormant "safe mode" stage, NASA quickly prepared an emergency repair and servicing mission with the space shuttle Discovery by dividing the regular maintenance and service mission scheduled for mid-2000 in two flights and launching the first one in December (see STS-103, above). The highly successful mission, during which the crew installed thirteen electronic systems and new protective blankets for the telescope, left it with a major increase in computer and data storage capability, new battery components, an upgraded guidance system and six new attitude gyros, laying the foundation for significant increases in observing capability as HST began its second decade in space.

Chandra. After several postponements during its development, testing, assembly and shipping, NASA's third "Great Observatory" (after Compton and Hubble), the massive Chandra X-ray Observatory was carried to orbit on 7/23 by the space shuttle Columbia (see STS-93, above). Named in honor of the late Indian-American astrophysicist and Nobel laureate Subrahmanyan Chandrasekhar, Chandra was formerly known as the Advanced X-ray Astronomy Facility (AXAF). With a total launch mass of 12,930 lbs. (5,870 kg), it is the largest satellite ever deployed by the space shuttle and the world's most powerful x-ray telescope. It uses a high-resolution camera, high-resolution mirrors and a charge-coupled detector (CCD) imaging spectrometer to observe, via x-rays, some of the most violent phenomena in the universe which cannot be seen by the Hubble's visual-range telescope. After barely two months in space, Chandra had already delivered a stunning image of the Crab Nebula, the spectacular remains of a stellar explosion, revealing something never seen before: a brilliant ring around the nebula's heart. Chandra also found long-sought "power lines" in the Crab, the most studied object in the sky, which connect the powerful spinning collapsed star with the luminous gas remnants around it. By the end of 1999, Chandra was well into its program of providing scientists with views of the high-energy universe never seen before which promise to revolutionize astronomical and cosmological concepts.

SOHO. In November, NASA engineers struggled to regain control of the European-U.S. Solar and Heliospheric Observatory (SOHO) after briefly losing contact with it. Cause was a "glitch" in the software which allows SOHO to operate without its gyroscopes. All three gyros had failed previously, and the new software was intended to enable the spacecraft to continue its science mission without them. A software patch returned the probe to normal operations.

By imaging strong ultraviolet reflections of sunspots on the far side of the Sun in the solar atmosphere, SOHO opened a way for scientists to study the backside of the Sun, out of view from Earth. This intriguing new discovery by French researchers could be used to predict solar storms threatening the Earth and future spacefarers much earlier than at present. New results from SOHO also indicate that the waves in the Sun's atmosphere are produced by vibrating solar magnetic field lines which give solar wind particles a push like an ocean wave pushes a surfer on a ride. In November, SOHO also tracked, along with NASA's Transition Region and Coronal Explorer (TRACE), a pass (transit) of the planet Mercury in front of the Sun for its entire duration of 51 minutes. The data will allow improved measuring of the Sun's outer atmosphere, or corona.

Galileo. Galileo in 1999 continued to return unprecedented data on Jupiter and its satellites, with several encounters with Jupiter's bizarre moons: one with Europa on 1/31, four with Callisto starting 5/5 and two with Io. The first one, on 10/11, was at 380 miles (612 km), yielding images 50 times better than the previous best picture of Io from Voyager 1 in 1979, and on 11/25, the probe flew by the colorful moon in a do-or-die effort at the extremely short range of only 187 miles (300 km) passage - and survived. Galileo, launched in October 1989, has revolutionized our knowledge about the mysterious, fascinating worlds of Jupiter's planetary system, offering tantalizing glimpses of possible life-supportive environments on some of the moons. On Europa, the probe in 1999 found sulfuric acid on the frozen surface, beneath which may lie a liquid ocean with bio-organic substances. This theory is supported by patterns of arc-shaped cracks in the surface, called cycloids, that are probably caused by tidal forces.

Cassini. Cassini, NASA's six-ton spacecraft heading to the planet Saturn on an epic 6.7-year, 3.2-billion-km journey, flew by the planet Venus on 6/24 and then made a close approach of Earth of 727 miles (1163 km) over the South Pacific on 8/17 (11:28pm EDT) on its last of three inner-planet flybys designed to accelerate the scientific probe toward its four-year mission at Saturn, beginning in 2004. During the Earth flyby it took a sequence of Moon photographs to calibrate its imaging science subsystem camera. In addition to the June and August flybys, Cassini has flown past Venus before in April 1998. The Earth passage gained the spacecraft a speed increase of 12,000 miles per hour (5.5 km/sec). A final planetary flyby, with Jupiter, will take place on 12/30/2000, boosting Cassini's velocity by 2.2 km/sec (5000 mph). The spacecraft remains in excellent health.

DS-1. NASA's Deep Space 1 (DS-1) technology test satellite on 7/29 undertook the closest encounter with an asteroid ever attempted when it flew within 10 miles (16 km) of the asteroid 1992 KD, newly named Braille. To alter its trajectory toward the rendezvous, DS-1 performed a six-week burn of its low-thrust xenon ion engine in March/April when it was more than 1.2 astronomical units (AU) from the Sun. With less than 70% of sunlight intensity of that at Earth available at that distance, the engine produced only about 0.14 ounces (40 milliNewtons) of thrust, but due to its extensive burn time it can effect trajectory changes while using little propellant (for example, a total of 9 kg of xenon gas have produced 545 m/s velocity change). DS-1 relied on its experimental autonomous navigation system AutoNav to guide itself past the asteroid. This system determines position by optically sighting on asteroids and stars, calculating the future trajectory, and devising and executing engine firings to meet the desired trajectory conditions. Launched on 10/24/98 on NASA's first Med-Lite version of the Boeing Delta 2 7326 booster (which uses only three solid strap-ons instead of nine) on its two-year voyage into a stretched-out elliptical orbit around the Sun, the spacecraft's mission is to test several advanced technologies for future interplanetary science missions, particularly the ion engine which uses electric power to accelerate ionized xenon fuel to over 18 miles per second (30 km/sec) for high-efficiency low-thrust (0.02 lbf, 9.4 grams). Other revolutionary technologies on board besides the AutoNav are testing power generation with concentrator solar arrays, Ka-band communications, and others.

If further tests go off as planned, DS-1 is tentatively scheduled for a flyby in January 2001 at the mysterious object Wilson-Harrington and, in September of the same year, at comet Borelly.

Lunar Prospector. By deliberately crashing the 660 lbs. (300 kg) spacecraft Lunar Prospector into the Moon at the end of its low-budget ($63 million) research mission in circumlunar orbit, NASA had hoped to get some evidence of whether there is hidden water ice on the Moon. The controlled crash of this third flight in NASA's Discovery Program of lower-cost, highly focused Solar System exploration, which had been launched on January 6, 1998, into a shadowed crater near the south pole did not produce any ultraviolet spectral lines of hydroxyl (OH) molecules in the cloud kicked up by the impact which would have been a water "signature".

QuickSCAT. NASA's Quick Scatterometer (QuickSCAT) mission to measure wind speed and direction over the world's oceans from space was launched on a Titan 2 on June 20. The 1914-lbs. (870 kg) spacecraft, which replaced a critical NASA "SeaWinds" instrument lost when Japan's ADEOS satellite failed in 1997, was placed in a sun-synchronous orbit of 98 degrees inclination and 499 miles (803 km) altitude. As an example of its uses, in September the SeaWinds radar tracked a large iceberg over a lengthy period which could have posed a threat to international shipping. The iceberg, measuring 24 x 48 miles (38 x 77 km), had detached from Antarctica seven years earlier.

ACE & Wind. The two NASA spacecraft ACE (Advanced Composition Explorer) and Wind during May found that the density of the solar wind dropped by more than 98%. This gave physicists the unique opportunity to observe particles (electrons) flowing directly from the Sun's corona to Earth. The severe change in the solar wind also changed the shape of the Earth's magnetic field (magnetosphere) and produced an unusual auroral display at the North Pole.

Stardust. NASA's comet probe Stardust was launched on 2/3 on a Delta 2 to begin its mission to intercept a comet and return close-up imagery and a soil sample to Earth. On its trajectory to its rendezvous with Comet Wild-2 in 2004, the spacecraft went suddenly into a safing mode on March 18. The computer had determined that it was carrying out an excessive number of functions during testing of the Stardust navigation camera and the return of its images to Earth. Controllers quickly commanded the probe back to a normal operational mode.

WIRE. The Wide-Field Infrared Explorer (WIRE) was launched on 3/4 on a Pegasus XL air-launched booster to conduct extra-galactic science surveys in the deep infrared. After deployment in orbit, the spacecraft was observed, during its first pass over the Poker Flat, Alaska, ground station, to be initially tumbling at 60 revolutions per minute, a rate higher than expected. After significant recovery efforts, WIRE was declared a loss on 3/8 after all solid hydrogen on board, necessary for the instrument, had been lost by inadvertent venting when the telescope instrument cover was ejected three days earlier than planned.

FUSE. NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) was launched on June 24 from Cape Canaveral on a Delta 2 Med-Lite vehicle. Following the liftoff, the 3000-lbs. (1360-kg) spacecraft was successfully placed into the targeted 480 mi. (768 km) orbit inclined 25 degrees against the equator, despite a misalignment of 5.3 degrees during its installation on top of the Delta booster. The spacecraft's mission is to characterize relationships between the interstellar medium and star formation and determine how much mass in the Universe was created during the Big Bang. The mission, of about $215 million total including the launcher, was the first developed for NASA by a university (Johns Hopkins), and France and Canada are participating with critical hardware.

NEAR. Almost three years after its liftoff in February '96, the Near Earth Asteroid Rendezvous (NEAR) spacecraft, NASA's second Discovery program mission, fired its engine on 1/3 to gain a second chance to meet and orbit the asteroid 433 Eros after a failure of the first of several rendezvous maneuvers on 12/20/98 changed plans. Instead of meeting its rendezvous with Eros in January 1999, NEAR was now set on a course to fulfill its research mission in mid-February 2000.

Mars exploration. In 1999 Mars continued to be the focus of excitement, even if partly for spectacular failure rather than success. Mars Global Surveyor continued to produce the highest resolution images of Mars to date, after concluding aerobraking into an operational orbit using atmospheric drag. Intended to investigate Mars on a global scale, the Mars Climate Orbiter suffered a stunning failure instead, followed by the disappearance of Mars Polar Lander. As investigations into the basic designs of low-cost robotic Mars missions are continuing, new missions are anticipated for 2001 and beyond, set to be launched in synodic period intervals of 26 months, preparatory to human expeditions now expected to follow in about the second decade after 2000.

Mars Global Surveyor. MGS was the first Surveyor-type Mars explorer of a series of probes planned for the next decade. After its arrival at Mars on 9/11/97, it started a long series of aerobrake passes around the planet. After reaching its operational orbit early in 1999, it began its mapping mission on 3/9. For the first three weeks, the mission proceeded with the spacecraft's 1.5-m (5 ft) high-gain antenna stowed due to concerns about the proper operation of its deployment mechanism. On 3/28, the antenna was successfully deployed. Since then, MGS has been transmitting a steady stream of high-resolution images of Mars. Overall, they showed that the red planet is a different place today than it was two years ago when the spacecraft arrived -- a world constantly 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. Today, Mars is a much more dynamic place than it was when the Viking spacecraft saw it in the late 1970s. In August, MGS' Mars Orbiter Camera succeeded in capturing images of the shadow of the Martian moon Phobos on the surface of the planet in western Xanthe Terras. Previously, MGS, for the first time in Mars exploration, mapped the full evolution of a Martian dust storm. Data from its Thermal Emission Spectrometer also supported the finding from Pathfinder that the red planet once had abundant water and thermal activity. Also for the first time, a three-dimensional picture of Mars' north pole was assembled from 2.6 million laser pulse measurements, with a spatial resolution of 0.6 miles (1 km) and a vertical accuracy of 15-90 ft (5-30 m). It allowed, for the first time, an estimate of the volume of the water ice cap with unprecedented precision, as well as study of surface variations and cloud heights in the region for the first time. MGS photographs of the Cydonia region, taken in 1998, also revealed the previously controversial "Face on Mars" to be an eroded mesa-like hill, as scientists had expected.

Mars Climate Orbiter. In September, NASA's Mars Climate Orbiter (MCO) prepared to enter orbit around Mars after a nine-months voyage from Earth where it had been launched on 12/11/98 on a Delta 2 rocket, for a nearly two-year study of the red planet's climate and the circulation of its atmosphere, and also, for the first several months after its arrival, to serve as a communications relay for the Mars Polar Lander. On 9/23, however, MCO failed to enter orbit due to navigation and maneuver errors caused by a mix-up in measurement units between two separate operations teams at Lockheed Martin and NASA's Jet Propulsion Laboratory (JPL). The numerical values used for trajectory modeling had been calculated in English units by spacecraft engineers and were mistakenly assumed, by spacecraft navigators calculating attitude control maneuvers, to be in metric units. As a result, MCO began its planned orbit insertion burn of 16m 23s duration at about 60 km (37.5 mi.) altitude, i.e., about 25 km (15.6 mi.) lower than what navigators had considered the minimal acceptable altitude for survival of the spacecraft, and thus was destroyed by atmospheric friction.

Mars Polar Lander. After the MCO loss, NASA's quickly established Mishap Investigation Board had about two months to investigate the cause of the failure and ensure that the Mars Polar Lander (MPL), due to arrive on 12/3, would not suffer a similar fate. Contact with MPL was lost as expected on 12/3 at 3:02 pm EST after the spacecraft had turned its antenna away from Earth by 75 degrees and shut off its transmitter in the process of assuming its proper entry attitude. Contact with the lander was never regained, and at the end of 1999 it remained unknown whether it had actually entered the Martian atmosphere and landed as planned at the so-called Mars Layered Deposits near the south pole, the first lander mission intended for a polar region of the planet. It is also not known whether its two Deep Space 2 (DS-2) penetrator microprobes, named Scott and Amundsen after Earth's famous south-pole explorers, had separated from the spacecraft before atmospheric entry and impacted on the surface. Despite intensive search efforts continuing at year's end no radio signals were received either from the lander nor the microprobes.

Pioneer 10. Launched from Cape Kennedy in 1972 aboard an Atlas/Centaur on a mission to Jupiter planned for only two years, the 570-lbs. (258-kg) Pioneer 10, the Earth's longest-lived interplanetary explorer, continues on its epic voyage to the stars as contact with it is still maintained by NASA's Deep Space Network. Currently at a distance of 11 billion kilometers (7 billion miles) from Earth, Pioneer 10 is passing through the transitional region between the farthest traces of the Sun's atmosphere, the heliosphere, still noticeable at that distance, and free intergalactic space. Signals transmitted by the little spacecraft today need 10 hours 10 minutes to reach Earth. Its course is pointed in the direction of the star Aldebaran, the "eye" of the constellation Taurus at a distance of 68 light-years (LY), which it will reach in two million years. But before that, at its current speed of 45,000 km/h (28,000 mph) the spacecraft will pass the red dwarf Proxima Centauri in 26,118 years, come within 3.2 LY of the red dwarf star Ross-248 in the Andromeda Nebula in 32,605 years, and fly by the white giant star Altair in 227,068 years.

The Earth Science

1999 was an important year for Earth Science, with $2 billion worth of observation systems launched into space. These civilian earth-observing missions, coordinated under the auspices of NASA's Earth Science Enterprise (ESE), began major new initiatives of a complex program that includes science and applications research, observational systems and technology development, and commensurate information system management, in cooperation with domestic and international partners. Its stated long-range goal is to enable policy and decision makers at all levels of government, public, and private sector practitioners to establish sound, knowledge-based environmental decisions in the 21st Century.

Landsat 7. As a major new part of NASA's Mission to Planet Earth program, the 4,662-lbs. (2100 kg) Landsat 7 Earth-imaging satellite was successfully launched on 4/15 on a Delta 2 into a 438-mi. (750-km) sun-synchronous polar orbit. The $650-million spacecraft traces its heritage to the earlier Landsat 4/5 series, the Defense Meteorological Satellite Program (DMSP) and the Tiros satellites. Mostly distinguished by its Enhanced Thematic Mapper Plus (ETM Plus), it is a considerable improvement over Landsat 6 which suffered a failed launch on a Titan rocket in 1993. Expectations are that with today's substantial cost reduction and systematic acquisition strategies employed with Landsat 7, its Earth observations will once again, as with the Landsats in the past, become the foundation for both terrestrial research and application activities.

Terra. As the first in a new spacecraft series -- the Earth Observation System (EOS) satellites -- the 10,506-lbs. (4765 kg) Terra was launched successfully on 12/18 on an Atlas/Centaur, the largest payload ever flown on that launcher. Formerly called EOS-AM-1, Terra achieved a 437-mi. (705-km) circular, sun-synchronous orbit, similar to Landsat 7 (which will have daily equatorial crossings four hours after Terra). The new spacecraft has five closely coupled science instruments for integrated studies of the Earth, from the top of its atmosphere down through its cloud layers to the surface of its seas and lands. Two smaller satellites in the series, EOS-PM and EOS-Chemistry, are in advanced stages of development for launches over the next two years. Altogether, the EOS program will eventually comprise 25 spacecraft of various sizes to be launched through 2003.

ACRIMSAT. The Active Cavity Radiometer Irradiance Monitor Satellite (ACRIMSAT) was launched on December 20 on an Orbital Science (OSC) Taurus rocket. The 115-kilogram (253-pound) satellite is currently circling Earth in a polar orbit at an altitude of 425 mi. (680 km). The instrument is designed to measure small, sustained changes in the total solar irradiance (TSI) of as little as 0.5% per century which could be the primary causal factor for significant climate change on time scales of many decades. There is mounting evidence that this has occurred in the past. Resolution of a century of TSI variation will require the flight of many instruments with overlapping missions to maintain the high precision of the data necessary to "see" the solar variability.

Department of Defense Space Activities

U.S. military space organizations continued their "cultural change" move 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 build a new technology 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.

Plans approved in 1997 for development of two new families of Evolved Expendable Launch Vehicles (EELVs) as successors to the Titan 4 in 1999 have resulted in two companies competing in the EELV program with their designs of boosters aimed at achieving a balance between cost, performance and system reliability as required for future government and commercial launch services: Lockheed Martin's Atlas 5 with the Russian RD-180 engine in the first stage and a Centaur-derived second stage, and Boeing's Delta 4 with a new cryogenic first stage engine (the Rocketdyne RS-68) and the Delta 3's upper stage with stretched tanks. Expected development costs for each of the two EELVs were approximately $1.5 billion.

Military launch attempts from Cape Canaveral and Vandenberg in 1999 totaled seven payloads, with two failures. Of particular importance was the launch of the 6000-lbs. (2720 kg) Advanced Research and Global Observation Satellite (Argos), the USAF's largest and most capable research and development satellite to date, on a Delta 2 on 2/23. Argos carries nine payload experiments, for 30 research objectives. Mission losses were incurred by an early warning satellite and a Milstar-2 communications satellite when their launch vehicles malfunctioned, the first, a Titan 4B/IUS, on 4/9, the second, Titan 4B/Centaur, on 4/30.

Commercial Space Activities

In 1999, as in the previous year, a strong, ongoing demand for satellites, launch vehicles, and ground equipment driven by the expansion of the telecommunications industry continued to keep the infrastructure segment of the space industry quite healthy.

The commercial telecommunications industry's continued need for geostationary satellites provides the launch market with a steady revenue base. In 1999, the development of LEO satellite constellations, which require a large number of small satellites in orbit, has begun to dramatically expand the market. While two satellite mobile-phone projects, Iridium LLC and ICO Global Communications Ltd., had to file for Chapter 11 U.S. bankruptcy protection late in 1999 (restructuring efforts have begun), other projects, like Globalstar and Orbcomm, have been more successful, with Globalstar getting ready to initiate a carefully phased "rollout" of its mobile satellite phone service in parts of the world covered by its first nine operational gateways.

While the year 1999 could be considered the year of the "dish" for communication satellites due to the boom in direct-broadcast-systems (DBS) subscribers, with direct-to-home services, according to published estimates, now accounting for one-quarter of industry revenues, for remote sensing satellites it stood out for breaking the 1-meter resolution barrier in the imaging market. The first attempt of achieving this breakthrough failed when the "Ikonos-1" satellite, a Lockheed Martin LM 900, was lost on 4/27 due to failed separation of the Athena-2's payload shroud. The second launch of the solid-propellant vehicle, on 9/24, was successful, however, and "Ikonos-2" became the first non-military satellite to provide high-resolution images with detail at the 1-m (3.3 ft) level to the commercial market. Compared to the 5m-resolution provided by the Indian IRS-1C/1D satellites, which allows map making at a 1:24,000 scale at best, Ikonos mappers can get scales up 1:2,400.

Problems encountered by commercial industries, not necessarily surprisingly, were late spacecraft deliveries, satellite export controls, political instability, launch failures, and increased competition. On the positive side, the first demonstration flight of Boeing's Sea Launch rocket was successful on 3/27 with the launch of a 4700-kg (10,300 lbs.) simulated Galaxy XI spacecraft into geosynchronous transfer orbit, followed by the success of the first commercial flight on 10/10 which launched the DirecTV-1R satellite for U.S.-wide digital television services. Sea Launch Co. was formed in April 1995 by Boeing Commercial Space Co., RSC-Energia of Russia, Kvaerner Maritime a.s of Norway, and KBYuzhnoye/PO Yuzhmash of the Ukraine, in response to growing market demand for a more affordable, reliable, and convenient commercial satellite launching service. The Sea Launch system consists of a floating mission control center and rocket-assembly factory ("Commander"), a self-propelled launch platform ("Odyssey"), and a Russian Zenit-3SL rocket.

Of the 33 total launch attempts by the United States in 1999 (vs. 36 in 1998), 25 were on commercial expendable launchers (NASA/Shuttle: 3; military/Titan 2 & 4: 5). Total number of U.S. commercial payloads was 70, with 41 launched on U.S. carriers and 29 on foreign launchers (China: 2; Russia: 25, Europe: 2). Only two of the 25 commercial launch attempts of expendable U.S. space carriers failed. Specifically, Boeing launched 10 Delta-2 vehicles, followed by Lockheed Martin with five Atlas 2A and three Pegasus XL of Orbital Sciences Corp. (OSC). However, Boeing's second launch of its new powerful Delta 3 with nine strap-on boosters, carrying the Orion 3 comsat, failed on 5/5 by placing the satellite in the wrong orbit, making it - after the loss of Ikonos-1 - the second of the two failures in 1999.