Sunday: April 7, 2002   0034 GMT Deep Space 1 finds Comet Borrelly has hot, dry surface Comets are sometimes described as "dirty snowballs," but a close flyby of one by NASA's Deep Space 1 spacecraft last fall detected no frozen water on its surface. Comet Borrelly has plenty of ice beneath its tar-black surface, but any exposed to sunlight has vaporized away, say scientists.    FULL STORY New study reveals twice as many asteroids as believed Asteroids in our Solar System may be more numerous than previously thought, according to the first systematic search for these objects performed in the infrared, with the European Space Agency's Infrared Space Observatory.    FULL STORY Saturday: April 6, 2002   0502 GMT Hubble resumes scientific work after servicing After three weeks of in-orbit checkout, following its deployment from space shuttle Columbia on March 9, the Hubble Space Telescope has been declared healthy and fit by engineers and scientists.    FULL STORY Atlantis to launch Monday NASA mission managers have picked Monday as the new launch date for shuttle Atlantis. The plan gives workers time to repair the hydrogen vent line leak and service Atlantis' fuel cells for another round of launch attempts.    MISSION STATUS CENTER Saturn-bound Cassini craft tweaks its trajectory NASA's Cassini spacecraft successfully completed a course adjustment this week during its journey toward Saturn. The maneuver was designed using new procedures the mission will employ for course adjustments while orbiting Saturn.    FULL STORY Friday: April 5, 2002   0050 GMT Hydrogen leak scrubs launch of shuttle Atlantis A significant hydrogen leak on the mobile launcher platform upon which the space shuttle sits forced NASA to scrub Thursday's attempt to launch Atlantis on its International Space Station assembly mission.    FULL STORY - updated    MISSION STATUS CENTER More mission coverage here:       Video coverage for subscribers only:    VIDEO: DRAMATIC VIDEO OF THE HYDROGEN LEAK QT or RV    VIDEO: POST-SCRUB BRIEFING BY LAUNCH DIRECTOR QT or RV    MORE: COMPLETE SFN+ VIDEO INDEX Radar pushes limits of asteroid impact prediction Applying unprecedented refinements to the analysis of celestial hazards, NASA astronomers have identified a potential close encounter with Earth more than eight centuries in the future by an asteroid two-thirds of a mile wide.    FULL STORY Process to deflect asteroids from Earth proposed Humans could deflect small but dangerous asteroids from Earth by changing how much sunlight the asteroids reflect, a planetary scientist suggests. Possible schemes might include covering the upper few centimeters of the asteroid with dirt, or painting its surface white, or fusing part of its surface with a spaceborne solar collector.    FULL STORY Thursday: April 4, 2002   0241 GMT Space agency reveals shuttle launch time The U.S. space agency lifted its tattered security blanket on Wednesday and revealed the official time for Thursday's planned launch of space shuttle Atlantis: 5:12:51 p.m. EST -- just one second earlier than amateur satellite observers had predicted and posted on the internet.    FULL STORY    MISSION STATUS CENTER - updates    NASA TV SCHEDULE Mission to install keystone truss to station expansion NASA resumes assembly of the international space station this week and next with launch of the shuttle Atlantis on a four-spacewalk flight to attach a 27,000-pound truss, the central component of a massive solar array-carrying beam that eventually will stretch the length of a football field.    FULL STORY    LAUNCH EVENTS TIMELINE    DETAILED MISSION FLIGHT PLAN    STS-110 FACTS AND FIGURES International Space Station science progress report A trio of Space Station experiments this week are zeroing in on the sources of vibrations that could disturb future delicate microgravity experiments. Meanwhile, Atlantis will launch carry the final five experiments planned for Expedition Four.    FULL STORY Hydrogen-fed bacteria may exist beyond Earth Primitive bacteria exist in huge numbers deep in the Earth, living on hydrogen gas produced in rocks, a NASA scientist reports in the spring issue of the journal Astrobiology. Recent studies suggest that the mass of bacteria existing below ground may be larger than the mass of all living things at the Earth's surface.    FULL STORY Wednesday: April 3, 2002   0246 GMT NASA starts counting down to Thursday's shuttle launch It began in secret sometime Monday but NASA says the three-day countdown to Thursday's launch of space shuttle Atlantis is underway at the Kennedy Space Center.    FULL STORY More mission coverage here:       Video coverage for subscribers only:    VIDEO: TUESDAY'S COUNTDOWN STATUS BRIEFING QT or RV    MORE: COMPLETE SFN+ VIDEO INDEX Why is Martian water found on north pole, not south? When astronauts finally land on Mars, a safe bet is that they'll head for northern climes if they intend to spend much time there. That's because nearly all the available water is frozen as ice at the north pole. Planetary scientists have been aware of this for some time, but they now have a new clue why it is so.    FULL STORY A mission brings black holes to light Black holes are perhaps the most elusive cosmic entity. Although we cannot see black holes, astronomers have confirmed their existence from the behavior of objects near the areas thought to be black holes. To learn more about these giant mysteries, scientists have to get a closer look at them.    FULL STORY Tuesday: April 2, 2002   0531 GMT Atlantis astronauts arrive for this week's launch The seven astronauts to fly aboard space shuttle Atlantis arrived at Kennedy Space Center Monday cloaked in NASA-ordered secrecy in preparation for the start of the three-day launch countdown. Liftoff is scheduled for Thursday afternoon.    MISSION STATUS CENTER    NASA WITHHOLDS LAUNCH TIME More mission coverage here:       Video coverage for subscribers only:    VIDEO: ASTRONAUTS ARRIVE IN T-38 JETS QT or RV    VIDEO: CREWMEMBERS' COMMENTS AFTER ARRIVAL QT or RV    MORE: COMPLETE SFN+ VIDEO INDEX Slip-up reveals sensitive shuttle launch time NASA's awkward efforts to keep shuttle launch times secret were dealt a blow last week when one of its contractors posted on the internet a target launch window for the space agency's most sensitive upcoming mission.    FULL STORY Engineering test could help plant growth in space The engineering test of a plant-growth system to be launched on this week's space shuttle mission to the International Space Station also may reveal important clues about plant development in space.    FULL STORY Russia launches classified military satellite payload A Molniya M rocket was launched from the Plesetsk Cosmodrome in Russia Monday night carrying a classified satellite payload into orbit for the military.    FULL STORY China dust disaster imaged by NASA spacecraft Dust covered northern China last week during some of the worst dust storms to hit the region in a decade. The dust obscuring China's Inner Mongolian and Shanxi Provinces on March 24 is compared with a relatively clear day in 2001 in these images from NASA's Terra Earth Observing Spacecraft.    FULL STORY Monday: April 1, 2002   1430 GMT Chinese unmanned space capsule returns to Earth The Chinese Shenzhou 3 spacecraft's descent module returned to Earth Monday, touching down one week after it launched on the third test flight of a prototype spacecraft that may one day carry humans into space.    FULL STORY Shuttle Atlantis poised for launch Thursday The seven astronauts to fly aboard space shuttle Atlantis this week are expected to arrive at Kennedy Space Center sometime Monday in preparation for the start of the three-day launch countdown. But both events are cloaked in NASA-ordered secrecy. Liftoff is scheduled for Thursday afternoon.    NASA WITHHOLDS LAUNCH TIME More mission coverage here:       Video coverage for subscribers only:    VIDEO: SPACE STATION PROGRAM UPDATE QT or RV    VIDEO: DETAILED OVERVIEW OF ATLANTIS' MISSION QT or RV    VIDEO: BRIEFING ON THE S0 TRUSS STRUCTURE QT or RV    VIDEO: PREVIEW OF MISSION'S FOUR SPACEWALKS QT or RV    VIDEO: MEET THE SEVEN ATLANTIS ASTRONAUTS QT or RV    MORE: COMPLETE SFN+ VIDEO INDEX New breed of auxiliary propulsion tested Engineers at the Marshall Space Flight Center in Huntsville, Ala., have begun a series of engine tests on a new breed of space propulsion: a Reaction Control Engine developed for the Space Launch Initiative (SLI) - a technology development effort to establish reliable, affordable space access.    FULL STORY Time changes might cancel some cosmic calculations Coupling two well known but previously uncombined scientific concepts might render moot certain prevailing assumptions used in studying the physics of fast moving particles and the universe in which they move. Physicists have long understood but never considered the interplay between the finite accuracy of clocks and how travelling at speeds approaching the speed of light distorts time.    FULL STORY				News Archive March 25-31: China's third Shenzhou launches; Intelsat 903 spacecraft launched by Proton booster; Ariane 4 launches a pair of commercial satellites; Project cleared to build Mercury orbiter; Chandra discovers black holes in distant quasars. March 18-24: Atlas 5 rocket passes crucial first launch pad test; New evidence: expansion of universe is accelerating; Bright new comet graces evening sky; New NASA communications satellite in trouble. March 11-17: Columbia returns from Hubble service call; Atlas 5 rocket tests; Researchers: Mars' features not eroded by water; Mars Odyssey's radiation experiment revived; Gravity mapping satellites launched. March 4-10: Spacewalks repair and refurbish Hubble; Atlas 2A launches NASA's Tracking and Data Relay Satellite; Report raises concerns about NASA safety; Color of universe corrected by astronomers. More news  See our weekly archive of space news. Contact us If you have a comment or question for Spaceflight Now, just send us an e-mail.