Text Size

SPACE FLIGHT 2004 - United States Space Activities
 

Launch activities in the United States in 2004 showed a sizable decrease from the relatively elevated level of the previous year. There were 19 NASA, DOD, and commercial launches, out of 19 attempts (2003: 26 of 27 attempts [loss of Columbia]; 2002: 18 of 18).

Space Shuttle. Because of the loss of Orbiter Columbia on the first shuttle mission in 2003, operations with the reusable shuttle vehicles of the U.S. Space Transportation System (STS) came to a halt for the remainder of the year and for 2004, as NASA and its contractors labored on intensive Return to Flight (RTF) efforts, with resumption of shuttle flights not expected until mid-2005. Resupply and crew rotation flights to the ISS were taken over solely by Russian Soyuz and Progress vehicles.

Advanced transportation systems activities. NASA's study activities of the original five-year Space Launch Initiative (SLI) project, announced in 2001, for developing the technologies to be used to build an operational reusable launch vehicle (RLV) before 2015 were terminated when in 2004 President George W. Bush announced NASA’s new long-range Vision for Space Exploration. New study activities will focus on concepts of the Vision’s CEV (Crew Exploration Vehicle) and heavy cargo lifters, with the goal to retire the space shuttle by 2010.

Space sciences and astronomy. In 2004, the U.S. launched four civil science spacecraft, one less than in the previous year: Gravity Probe-B, Aura, Messenger, and Swift.

Gravity Probe-B. Gravity Probe-B (GP-B) is a NASA mission to test two predictions of Albert Einstein's Theory of General Relativity. Launched on April 20 (9:57:24am PDT) on a Delta 2 rocket, the 3100-kg spacecraft, orbiting 400 miles above Earth, uses four ultra-precise gyroscopes to test Einstein's theory that space and time are distorted by the presence of massive objects. To accomplish this, the mission measures two fa ctors: how space and time are warped by the presence of the Earth, and how the Earth's rotation drags space-time around with it. In early September, the probe achieved a major milestone with the completion of the Initialization & Orbit Calibration (IOC) phase of its mission and the transition into the science phase, bringing the GP-B mission one step closer to shedding new light on the fundamental properties of our universe. NASA's Marshall Space Flight Center manages the GP-B program, with Stanford University, the prime mission contractor, who conceived the experiment, responsible for the design and integration of the science instrument, as well as for mission operations and data analysis. Lockheed Martin, a major subcontractor, designed, integrated and tested the space vehicle and built some of its major payload components.

MESSENGER.NASA's MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging) - set to become the first spacecraft to orbit the planet Mercury - was launched on August 3 (at 2:15:56am EDT) aboard a Delta 2 rocket from Cape Canaveral Air Force Station, Fla. The approximately 1.2-ton (1,100-kilogram) spacecraft, designed and built by the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, MD, was placed into a solar orbit 57 minutes after launch, targeted to begin orbiting Mercury in 2011. During a 4.9-billion mile (7.9-billion kilometer) journey that includes 15 trips around the sun, MESSENGER will fly past Earth once, Venus twice and Mercury three times before easing into orbit around its target planet. The Earth flyby, on August 2, 2005, and the Venus flybys, in October 2006 and June 2007, will use the pull of the planets' gravity to guide MESSENGER toward Mercury's orbit. The Mercury flybys in January 2008, October 2008 and September 2009 help the probe match the planet's speed and location for an orbit insertion maneuver in March 2011. The flybys also allow the spacecraft to gather data critical to planning a yearlong orbit phase. Since MESSENGER is only the second spacecraft sent to Mercury - Mariner 10 flew past it three times in 1974-75 and gathered detailed data on less than half the surface - the mission has an ambitious science plan. With a package of seven science instruments MESSENGER will determine Mercury's composition; image its surface globally and in color; map its magnetic field and measure the properties of its core; explore the mysterious polar deposits to learn whether ice lurks in permanently shadowed regions; and characterize Mercury's tenuous atmosphere and Earth-like magnetosphere.

Swift.NASA's Swift satellite successfully launched on November 20 (12:16pm EST) aboard a Delta 2 rocket from Launch Complex 17A at the Cape Canaveral Air Force Station, Fla. The satellite was designed and built with international participation (England, Italy) to solve the 35-year-old mystery of the origin of gamma-ray bursts (GRBs). Scientists believe the bursts, distant yet fleeting explosions, are related to the formation of black holes throughout the universe - the birth cries of black holes. Each gamma-ray burst is a short-lived event, lasting only a few milliseconds to a few minutes, never to appear again. They occur several times daily somewhere in the universe, and Swift should detect several weekly. To track these mysterious bursts, Swift carries a suite of three main instruments. The Burst Alert Telescope (BAT) instrument, built by Goddard, will detect and locate about two gamma-ray bursts weekly, relaying a rough position to the ground within 20 seconds. The satellite will swiftly re-point itself to bring the burst area into the narrower fields of view of the on-board X-ray Telescope (XRT) and the UltraViolet/Optical Telescope (UVOT). These telescopes study the afterglow of the burst produced by the cooling ashes that remain from the original explosion. During its 2-year mission, Swift is expected to observe more than 200 gamma-ray bursts - the most comprehensive study of GRB afterglows to date.

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 - the GALEX telescope 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 2004, among else, astronomers using GALEX’s sensitive ultraviolet detectors have detected three-dozen bright, compact galaxies that greatly resemble the youthful galaxies of more than 10 billions years ago. These new galaxies are relatively close to us, ranging from two to four billion light-years away. They may be as young as 100 million to one billion years old (the Milky Way is approximately 10 billion years old). This discovery suggests our aging universe is still alive with youth. It also offers astronomers their first, close-up glimpse at what our galaxy probably looked like when it was in its infancy.

Spitzer Space Telescope (SST), formerly known as SIRTF (Space Infrared Telescope Facility) and launched on August 24, 2003, 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 2004, among else, Spitzer discovered for the first time dusty discs around mature, Sun-like stars known to have planets, and the Hubble Space Telescope captured the most detailed image ever of a brighter disc circling a much younger Sun-like star. The findings offer "snapshots" of the process by which our own solar system evolved, from its dusty and chaotic beginnings to its more settled present-day state. The young star observed by Hubble is 50 million to 250 million years old. This is old enough to theoretically have gas planets, but young enough that rocky planets like Earth may still be forming. The six older stars studied by Spitzer average 4 billion years old, nearly the same age as the Sun. They are known to have gas planets, and rocky planets may also be present. Prior to these findings, rings of planetary debris, or "debris discs," around stars the size of the Sun had rarely been observed, because they are fainter and more difficult to see than those around more massive stars. Debris discs around older stars the same size and age as our Sun, including those hosting known planets, are even harder to detect. These discs are 10 to 100 times thinner than the ones around young stars. Spitzer's highly sensitive infrared detectors were able to sense their warm glow for the first time.

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 2004 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. In 2004, among else, RHESSI was taken off the Sun to point at the Crab Nebula, to obtain the finest imaging ever done of a cosmic source in the hard x-ray/soft gamma-ray range.

Hubble Space Telescope. Fourteen 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. 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 2004, scientists using the HST measured the age of what may be the youngest galaxy ever seen in the universe. Called I Zwicky 18, at a distance of 45 million light years, it may be as young as 500 million years old (so recent an epoch that complex life had already begun to appear on Earth). The Milky Way galaxy by contrast is over 20 times older, or about 12 billion years old, the typical age of galaxies across the universe. This "late-life" galaxy offers a rare glimpse into what the first diminutive galaxies in the early universe look like. On Jupiter, HST spotted a rare triple eclipse: a rare alignment of three of Jupiter's largest moons – Io, Ganymede, and Callisto – across the planet's face. Other momentous accomplishments of the HST in 2004 were the explosion of a massive star blazing with the light of 200 million Suns, called a supernova. The supernova is so bright that it easily could be mistaken for a foreground star in the Milky Way, but in reality this supernova, called SN 2004dj, resides far beyond our galaxy,- in the outskirts of NGC 2403, a galaxy located 11 million light-years from Earth. Although the supernova is far from Earth, it is the closest stellar explosion. In 2004, 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 fourth 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 had 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 2004 Chandra’s most popular image was a spectacular new image of Cassiopeia A that had nearly 200 times more data than the "First Light" Chandra image of this object made five years ago. The new image reveals clues that the initial explosion caused by the collapse of a massive star was far more complicated than suspected. Also in 2004, an international team of scientists used Chandra data to measure the temperature of the pulsar at the center of 3C58, the remains of a star observed to explode in the year 1181. Chandra's image of 3C58 also showed spectacular jets, rings and magnetized loops of high-energy particles generated by the pulsar. Data indicated that the surface of the 3C58 pulsar has cooled to a temperature of slightly less than a million degrees Celsius, which is extremely cool for a young neutron star. Pulsars are formed when the central core of a massive star collapses to create a dense object about 15 miles across that is composed almost entirely of neutrons. Collisions between neutrons and other subatomic particles in the interior of the star produce neutrinos that carry away energy as they escape from the star. This cooling process depends critically on the density and type of particles in the interior, so measurements of the surface temperature of pulsars provide a way to probe extreme conditions where densities are so high that our current understanding of how particles interact with one another is limited. They represent the maximum densities that can be attained before the star collapses to form a black hole.

Cassini/Huygens. NASA’s six-ton (5.4-metric-ton) spacecraft Cassini continued its epic 6.7-year, 3.2-billion-km journey to the planet Saturn. During 2004, the spacecraft remained in excellent health and successfully entered orbit around Saturn on June 30, when at 9:12pm PDT flight controllers received confirmation that Cassini had completed the engine burn needed to place the spacecraft into the correct orbit. This began a four-year study of the giant planet, its majestic rings and 31 known moons. Already in August, the probe discovered two new moons, approximately 3 kilometers (2 miles) and 4 kilometers (2.5 miles) across -- smaller than the city of Boulder, CO. The moons, located 194,000 kilometers (120,000 miles) and 211,000 kilometers (131,000 miles) from the planet's center, are between the orbits of two other Saturnian moons, Mimas and Enceladus. They were provisionally named S/2004 S1 and S/2004 S2. One of them, S/2004 S1, may be an object spotted in a single image taken by NASA's Voyager spacecraft 23 years ago, called at that time S/1981 S14. Pictures and data taken during the first close flyby of Saturn's moon Titan by Cassini revealed greater surface detail than ever before and showed that Titan has lost much of its original atmosphere over time. The surface appears to have been shaped by multiple geologic processes. Although a few circular features can be seen, none can be definitively identified as impact craters. On December 24, the Huygens probe successfully detached from NASA's Cassini orbiter to begin a three-week journey to Saturn’s moon Titan. NASA's Deep Space Network tracking stations in Madrid, Spain, and Goldstone, Calif., received the signal at 7:24pm PST. The Huygens probe, built and managed by ESA, was bolted to Cassini and has been riding along during the nearly seven-year journey to Saturn largely in a "sleep" mode. Set to touch on Titan on January 14, 2005, Huygens will be 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. By end-2004, its mothership had found Saturn roiled with storms, detected lighting, discovered a new radiation belt, found four new moons, a new ring around the planet and mapped the composition of the planet’s rings. On December 31, Cassini capped off the year with an encounter of Saturn's "yin-yang" moon Iapetus, on the probe’s closest pass yet by one of Saturn’s smaller icy satellites since its arrival around the ringed giant. The next close flyby of Iapetus, a world of sharp contrasts, is not until 2007. Its leading hemisphere is as dark as a freshly-tarred street, and the white, trailing hemisphere resembles freshly-fallen snow, resembling the yin-yang symbol.

WMAP. NASA's Wilkinson Microwave Anisotropy Probe (formerly called the Microwave Anisotropy Mission, MAP) was launched on June 30, 2001, on a Delta-2. Now located in an orbit around the second Lagrange libration point L2, its differential radiometers measure the temperature fluctuations of the cosmic microwave background radiation (CMBR) with unprecedented accuracy. 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 at 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). Fast moving neutrinos do not play any major role in the evolution of structure in the universe (they would have prevented the early clumping of gas in the Universe, delaying the emergence of the first stars, in conflict with the new WMAP data). The expansion rate of the Universe, called the Hubble Constant, is Ho= 71 km/sec/Mpc (megaparsecs) with a margin of error of about 5%. There is new evidence for Inflation (in polarized signal), and for the theory that fits all data, the Universe will expand forever. (But the nature of the dark energy remains a mystery. If it changes with time, or if other unknown and unexpected things happen in the universe, this conclusion could change.)

Genesis. The solar probe Genesis was launched on August 8, 2001, on a Delta 2 rocket into a perfect orbit about the first Earth-Sun Lagrangian libration point L1 about 1.5 million km from Earth and 148.5 million km from the Sun on November 16, 2001. After an unconventional "Lissajous Orbit Insertion" (LOI), Genesis began the first of five "halo" loops around L1, lasting about 30 months. Collection of samples of solar wind material expelled from the Sun started on October 21, 2001. One year later, on December 10, 2002, with the spacecraft in overall good health and spinning at 1.6 rotations per minute, its orbit around L1 was fine-tuned with the seventh of 15 planned station-keeping maneuvers during the lifetime of the mission. Throughout 2003, Genesis continued its mission of collecting solar wind material, with all spacecraft subsystems still reported in excellent health. In April 2004, the sample collectors were deactivated and stowed, and the spacecraft returned to Earth, where the sample return capsule was to be recovered in mid-air by helicopter over the Utah Test & Training Range on September 8, 2004. However, Genesis’ return did not go according to plan. The vessel, which had spent 27 months collecting data and samples of the solar wind, entered Earth's atmosphere as scheduled on 9/8, but its parachutes failed to deploy and the capsule crashed into the Utah desert at nearly 200 miles an hour. After the crash, the 400-pound capsule was recovered and transported by helicopter to a nearby Army base equipped with a clean room for analysis. In October scientists reported that a large amount of material within the Genesis scientific collectors had remained intact and will provide useful information about the beginning and development of our solar system.

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. ACE in 2004 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. The spacecraft has enough propellant on board to maintain an orbit at L1 until ~2019. By end-2004, ACE has been at the L1 point for more than 7 years, and things were still working very well, with the exception of the SEPICA (Solar Energetic Particle Ionic Charge Analyzer) instrument. SEPICA had trouble with the gas regulation of its proportional counters and with a high-voltage power supply. Two-thirds of the instrument were non-functional, but the third counter was returning good science data. The problems are still under investigation. As of Spring 2004, over 350 peer reviewed papers had been published by ACE science team members.

Stardust. In January 2004, having weathered a strong “sandblasting” by cometary particles hurtling toward it at about six times the speed of a rifle bullet, NASA's comet probe Stardust spacecraft, launched on February 3, 1999 on a Delta 2, passed by Comet P/Wild 2, collected particles and began its two-year, 1.14 billion kilometer (708 million mile) trek back to Earth. The probe had entered the comet's coma - the vast cloud of dust and gas that surrounds a comet's nucleus - on December 31, 2003. From that point on it kept its defensive shielding between it and what scientists hoped would be the caustic stream of particles it would fly through. Before its closest approach to the comet, Stardust's trajectory made three loops around the Sun. After one solar orbit, an Earth flyby was used to boost the spacecraft orbit on January 15, 2001 and a second period of interstellar dust collection was opened July to December 2002. On November 2, 2002 Stardust passed within 3000 km of asteroid 5535 Anne Frank, at 7 km/sec relative velocity. A second orbit of the sun was completed in mid-2003 and the comet P/Wild 2 encounter followed then 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. The sample collector was deployed in late December 2003 and retracted, stowed, and sealed in the vault of the sample reentry capsule after the Wild fly-by. Images of the comet nucleus were also obtained, with coverage of the entire sunlit side at a resolution of 30 m or better. On January 15, 2006 the capsule will separate from the main craft (with a stabilizing spin of 1.5 rpm) and re-enter Earth's atmosphere. A parachute will be deployed, and a chase aircraft will “snatch” and recover the descending capsule over the U.S. Air Force Test & Training Range in the Utah desert. Special engineering analyses were performed to ensure that Stardust will not suffer the same fate as Genesis.

Ulysses. In 2004, the joint European/NASA solar polar mission Ulysses continued. Launched in 1990 on shuttle mission STS-41 to study the Sun’s polar regions, the mission in 2004 was in its 14th year, and all spacecraft systems and the nine sets of scientific instruments remain in excellent health. Ulysses arrived over the sun's south polar regions for the second time in November 2000, followed by the rapid transit from maximum southern to maximum northern helio-latitudes that was completed in October 2001. Solar activity reached its maximum in 2000, so that Ulysses experienced a very different high-latitude environment from the one it encountered during the first high-latitude passes. In June 2004, the spacecraft again reached aphelion, its farthest point from the sun, after passing through its critical eighth conjunction on August 30, 2003 (where Earth, Sun and spacecraft are aligned with the Sun in the middle). Ulysses' signals are transmitted to its operations center at NASA’s Jet Propulsion Laboratory in Pasadena, California. In February 2004, ESA's Science Program Committee unanimously approved a proposal to continue operating the highly successful Ulysses spacecraft until March 2008. This latest extension, the third in the history of the joint ESA-NASA mission, will enable Ulysses to add an important chapter to its survey of the high-latitude heliosphere. In 2007 and 2008, the space probe will fly over the poles of the Sun for a third time. Unlike the past high-latitude passes in 2000 and 2001 that brought Ulysses over the solar poles near the maximum of the Sun's activity cycle, conditions for the third set of polar passes are expected to be much quieter. In fact, they are likely to be similar to those in 1994/1995 when Ulysses first visited the Sun's poles.

Voyager. The Voyager mission, now in its 28th year, continues its quest to push the bounds of space exploration. The twin Voyager 1 and 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 2003, Voyager 1 set a new milestone, when on November 5 the spacecraft reached 90 astronomical units (AU) from the Sun (i.e., about 8.4 billion miles or 13.5 billion kilometers). Voyager 1 is the most distant human-made object in the universe. At end-2004, the spacecraft was about 94 times as far from the Sun as is Earth. It was deflected northward above the plane of the planets' orbits when it swung by Saturn in 1980 and is now speeding outward from the Sun at nearly one million miles per day, a rate that would take it from Los Angeles to New York in less than four minutes. Long-lived nuclear batteries are expected to provide electrical power until at least 2020 when Voyager 1 will be more than 13 billion miles from Earth and may have reached interstellar space. The only spacecraft to have made measurements in the solar wind from such a great distance from the source of the dynamic solar environment, it is now at 8.7 billion miles from the Sun and has entered the solar system's final frontier, the so-called heliosheath beyond the termination shock of the solar wind, a vast, turbulent expanse where the Sun's influence ends and the solar wind crashes into the thin gas between stars. Close on the heels of its twin 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. In July 2003, Voyager 2 had reached a distance from the Sun of 10.6 billion km (70 AU). At end-2004 (exactly on January 5, 2005) it was 10,000 days since Voyager 2's launch. It too continues to go strong, returning valuable science data. Each Voyager's cosmic ray detector, magnetometer, plasma wave detector and low-energy charged particle detector all still operational. In addition, the Ultraviolet Spectrometer on Voyager 1 and the Plasma Science instrument on Voyager 2 are producing and transmitting data. Both spacecraft are expected to continue to operate and send back valuable data until at least the year 2020.

Mars exploration. The year 2004 began with the successful landing and deployment of the two Mars Exploration Rovers Spirit and Opportunity, after their headline-making launches in 2003, at near-equatorial locations on opposite sides of Planet Mars. The interplanetary navigation systems enabled exceptionally accurate achievement of the desired atmospheric entry conditions for both mobile geology laboratories, and the actual surface landing points differed from the targets by only 10 km for Spirit and 25 km for Opportunity. In April 2004, both rovers successfully completed their primary three-month missions and went into bonus overtime work for the remainder of the year.

Spirit (MER-A). The six-wheeled rover vehicle Spirit, launched on June 10, 2003, on a Delta 2 Heavy rocket, landed on January 3 (Eastern Time) almost exactly at its intended landing site in Gusev Crater in excellent condition. During 2004, Spirit completed a two-mile trek to a formation called Columbia Hills (after the lost shuttle), where it found a water-signature mineral called goethite in bedrock, one of the mission's surest indicators yet for a wet history on Spirit's side of Mars. Spirit, during its primary mission, explored a plain strewn with volcanic rocks and pocked with impact craters. It found indications that small amounts of water may have gotten into cracks in the rocks and may also have affected some of the rocks’ surfaces. This did not indicate a particularly favorable past environment for life. Spirit’s Extended Mission began with the rover starting a long trek toward a range of hills on the horizon whose rocks might have come from an earlier and wetter era of the region’s past. In late September 2004, NASA approved a second extension of the rovers’ missions. The solar-powered machines were still in good health, though beginning to show signs of aging. They had come through the worst days of the Martian year from a solar-energy standpoint. Also, they had resumed full operations after about two weeks of not driving in mid-September while communications were unreliable because Mars was passing nearly behind the Sun. Spirit had driven 3.6 kilometers (2.25 miles), six times the goal set in advance as a criterion for a successful mission. It was climbing hills where its examinations of exposed bedrock found more extensive alteration by water than what the rover had seen in rocks on the younger plain. During the long trek, Spirit’s right front wheel developed excessive friction. Controllers found a way to press on with the exploration by sometimes driving the rover in reverse with the balky wheel dragging.

Opportunity (MER-B). NASA’s second Mars explorer, twin to Spirit, launched on July 7 (Eastern), 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. Opportunity had driven about 1.6 kilometers (1 mile). It was studying rocks and soils inside a crater named Endurance, about 130 meters (430 ft) wide and 22 meters (72 ft) deep. The rover entered this crater in June 2004 after careful analysis of its ability to climb back out. Inside, Opportunity examined layer upon layer of bedrock with characteristics similar to those of the outcrop inside the smaller crater where it landed. This indicated a much longer duration for the watery portion of the region’s ancient past. The rover also found some features unlike any it had seen before, evidence of changes in the environment over time. Whether the rovers’ unpredictable life spans would extend only a few more days or several more months into 2005, they have already racked up successes beyond the high expectations set for them when the Mars Exploration Rover project began.

Mars Odyssey. The Mars Odyssey probe, launched April 7, 2001, successfully 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, reduce 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 Mars 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 an extended mission through September 2006. About 85 percent of images and other data from NASA's twin Mars rovers, Spirit and Opportunity, have reached Earth via communications relay by Odyssey, which receives transmissions from both rovers every day. The orbiter helped analyze potential landing sites for the rovers and is doing the same for NASA's Phoenix mission, scheduled to land on Mars in 2008. Plans also call for Odyssey to aid NASA's Mars Reconnaissance Orbiter, due to reach Mars in March 2006, by monitoring atmospheric conditions during months when the newly arrived orbiter uses calculated dips into the atmosphere to alter its orbit into the desired shape.

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. 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 March 28, 1999, the antenna was successfully deployed. Since then, MGS has been transmitting a steady stream of high-resolution images of Mars, 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 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. Through 2003, imagery and transmissions continued. On May 8, it succeeded in capturing six other celestial bodies in a single photographic frame: taking advantage of an alignment in the orbits of Earth and Jupiter, MGS delivered a sensational picture that included the two planets, plus our Moon and three of Jupiter’s four Galilean satellites – Callisto, Ganymede and Europa. 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 showed actual wheel tracks of the Mars Exploration Rover Spirit and the rover itself. Another told scientists that no boulders bigger than about 1 to 2 meters (3 to 7 feet) are exposed in giant ripples created by a catastrophic flood. The new technique involves rolling the entire spacecraft so that the camera compensates image motion while scanning, in this way able to show details at three times higher resolution than is normally obtained.

Earth Science In 2004, NASA launched one Earth science satellite, the Aura.

Aura. Aura (Latin for “breeze”), launched from Vandenberg AFB on July 15 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 2004, observations from Aura showed that ozone destroyed chemically in the Arctic last winter in near-record levels was restored by other atmospheric processes to near average amounts, stopping high levels of harmful ultraviolet radiation from reaching Earth's surface. The answer appeared to lie in this year's unusual Arctic atmospheric conditions, which caused polar ozone being replenished by shifted stratospheric winds, transporting ozone-rich air from Earth's middle latitudes into the Arctic polar region.

ICESat . (Ice, Cloud, and land Elevation Satellite) is the latest Earth Observing System (EOS) spacecraft and 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. For example, in winter 2004, ICESat showed thicker sea ice grouped together in its usual place near the Canadian Arctic than it was in 2003. It also showed a larger area of thinner ice in the Beaufort and Chukchi Seas where the summer ice cover has been rapidly decreasing. The location and amount of ice is important to climatologists and also ships that travel those seas.

Aqua . Aqua was launched by NASA in 2002. Formerly named EOS PM (signifying its afternoon equatorial crossing time), Aqua is part of the NASA-centered international Earth Observing System (EOS). Since May 2002, the 1750 kg (3858 lb) satellite, 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. Aqua joined Terra, launched in 1999, and was followed by Aura in 2004 (see above).

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 the National Oceanic and Atmospheric Administration (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.

GRACE. Launched on March 17, 2002, on a Russian Rockot carrier, the twin satellites GRACE (Gravity Recovery and Climate Experiment), named "Tom" and "Jerry", are mapping the Earth's gravity fields by taking accurate measurements of the distance between the two satellites, using 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. GRACE provides scientists from all over the world with an efficient and cost-effective way to map the Earth's gravity fields with unprecedented accuracy, yielding crucial information about the distribution and flow of mass within the Earth and its surroundings. Its science data are being used to estimate global models for the mean and time variable Earth gravity field approximately every 30 days for the 5 year lifetime of the mission. The science data from GRACE consist of the inter-satellite range change measurements, and the accelerometer, GPS and attitude measurements from each satellite. The project is a joint partnership between NASA and the German DLR (Deutsches Zentrum für Luft- und Raumfahrt).

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 use of space systems within military operations reached a new and distinct mark in 2002 for the war on terrorism and operations in Afghanistan and subsequently in Iraq in 2003 and 2004. The increased use of satellites for communications, observations, and – through the Global Positioning System (GPS) – navigation and high-precision weapons targeting was and is of decisive importance for the military command structure. Orbiting assets ably demonstrated during the Iraq conflict and thereafter 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 2004, there were five military space launches (2003: 11), carrying five payloads: one Titan 4B/IUS vehicle from Cape Canaveral, Florida, with the DSP-022 early warning satellite, three Delta 2s with GPS navigation satellites, and one Atlas 2 AS with an NRO communications satellite.

Commercial space activities. In 2004, commercial space activities in the United States exhibited a sluggish increase over prior years, after the 2001/2002 downturn in the communications space market caused by failures of satellite constellations for mobile telephony and a slight recovery in 2003.

In addition to the financial problems, some difficulties remained due to the export restrictions imposed to the US industry on sensitive technologies. In general, commercial ventures continue to play a relatively minor role in US space activities, about as in 2001 (50%), but more than the 26% in 2002 and 31% in 2003, of commercial satellites and associated launch services worldwide.

Of the 19 total launch attempts by the United States in 2004 (26 in 2003), ten were commercial missions (NASA: 4; military: 5). In the launch services area, Boeing sold seven Delta-2 vehicles, while competitor ILS/Lockheed Martin flew four Atlas 2AS and one Atlas 3B (with Russian engines). Both companies also had successful launches of their next-generation EELV (evolved expendable launch vehicle) rockets, viz., Lockheed Martin with the fourth Atlas 5/Centaur (comsat AMC-16), and Boeing with the first Delta 4H (heavy) launcher (Demosat, plus imaging test satellites 3CS-1 and 3CS-2), while the partnership of Boeing, RSC-Energia (Russia, 25% share), NPO Yushnoye (Ukraine) and Kvaerner Group (Norway) successfully launched three Russian Zenit 3SL rockets carrying Brazil’s Estrela do Sul (Telstar 14), US DirecTV-7S and China’s Telstar 18 comsats from the Odyssey sea launch platform floating at the Equator (first launch 1999).

2004, however, was a historic year for privately funded personal space travel. On June 21, SpaceShipOne, a joint venture between Vulcan and the Scaled Composites Company of Burt Rutan became the first commercial spacecraft when it rocketed beyond the 100-km threshold of space, launched from its piloted mother ship/airplane White Knight, reaching 100,124 m (328,491 ft) with pilot Mike Melvill. After this test flight, on September 29 SpaceShipOne made the first of the two flights for the Ansari X-Prize of $10-million, again piloted by Mike Melvill (who had to control over 25 unscheduled rolls) plus ballast representing a second passenger to 102.9 km, followed on October 4 by the second flight, with Brian Binnie at the helm, to 112 km. Already in 2003 the mother ship/airplane White Knight and SpaceShipOne had made their first flight, on May 20 to 15 km (nearly 50,000 ft), both remaining joined. The first gliding flight of the latter then followed on August 7, after separation from the carrier aircraft at 14.3 km (47,000 ft).