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Opportunity Prepares for Launch Odyssey Orbiter Reveals Mars' Icy

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Opportunity Prepares for Launch Odyssey Orbiter Reveals Mars' Icy Inside July 3, 2003 Volume 33 Number 13 News Briefs . 2 One NASA: Columbia recovery . 3 Special Events Calendar . 2 Passings, Letters . 4 This Month in History . 2 Retirees, Classifieds . 4 Jet Propulsion Laboratory The launch of “Opportunity,” circumference, would be rein- accelerate the spacecraft in a the second of JPL’s twin Mars stalled. direction perpendicular to the Exploration Rovers, has been Following its scheduled Jan. rotation axis fired in pulses Opportunity postponed to no earlier than 25, 2004 landing in Meridiani timed to the spacecraft’s rota- Saturday, July 5. Planum, Opportunity will join its tion rate—with 264 pulses total- prepares NASA decided on Monday, twin, Spirit, in a quest to under- ing about 22 minutes of burn June 30 to take additional time stand the role of water on Mars. time. The total maneuver in- to perform tests on the process Plans call for each rover to creased Spirit’s speed by 14.3 for launch used to bond the cork insulation operate for at least three meters per second (32 mph). to the surface of the Delta II months. At the end of the trajectory launch vehicle. These tests were Spirit, which was launched correction, Spirit performed an scheduled to be completed late June 10, performed its first attitude turn that adjusted its Wednesday, July 2. trajectory correction maneuver orientation in space to maintain The launch times on July 5 are June 20. the optimal combination of 7:51 p.m. and 8:34 p.m. PDT. Following commands from the facing its solar array toward the NASA engineers inspected the Mars Exploration Rover flight Sun and pointing its low-gain first stage of the Delta vehicle team at JPL, Spirit first per- antenna toward Earth. All sys- Opportunity, the second after a June 28 attempt to formed a calibration and check tems on the spacecraft are in Mars Exploration launch Opportunity, and found of its eight thrusters, then fired good health. that a lower band of cork insula- the thrusters to fine-tune its Spirit’s next trajectory correc- Rover, required repairs tion that was removed and re- flight path toward Mars. tion maneuver is scheduled for and will launch no placed had limited areas that The main burn had two com- Aug. 1 and its next attitude turn earlier than July 5. debonded from the surface of ponents. Thrusters that acceler- for July 22. the vehicle. ate the rotating spacecraft along Spirit will arrive at Mars on NASA announced Sunday, June the direction of the rotation axis Jan. 4, 2004, Universal Time 29 that sections of this band, burned steadily for about 28 (evening of Jan. 3, 2004, East- approximately 10 percent of the minutes. Then, thrusters that ern and Pacific times). JPL’s Mars Odyssey spacecraft is revealing new details about the other hand, the neutron detector loses sensitivity to measure carbon- intriguing, dynamic character of the frozen layers now known to domi- dioxide thickness greater than 1 meter (3 feet), where the altimeter Odyssey nate the high northern latitudes of Mars. The implications have a bear- obtained reliable data. Working together, we can examine the whole ing on science strategies for future missions in the search of habitats. range of dry ice snow accumulations.” orbiter Odyssey’s neutron and gamma ray sensors tracked seasonal changes “The synergy between the measurements from our two ‘eyes in the as layers of “dry ice” (carbon-dioxide frost or snow) accumulated during skies of Mars’ has enabled these new findings about the nature of near- northern Mars’ winter and then dissipated in the spring, exposing a soil surface frozen materials, and suggests compelling places to visit in reveals layer rich in water ice, the Martian counterpart to permafrost. future missions in order to understand habitats on Mars,” said Dr. Jim Researchers used measurements of Martian neutrons, combined with Garvin, NASA’s lead scientist for Mars exploration. height measurements from the laser altimeter on another JPL space- Another report, to be published in the Journal of Geophysical Re- Mars’ icy craft, Mars Global Surveyor, to monitor the amount of dry ice during the search-Planets, combines measurements from Odyssey and Global northern winter and spring seasons. Surveyor to provide indications of how densely the winter layer of car- character “Once the carbon-dioxide layer disappears, we see even more water bon-dioxide frost or snow is packed at northern latitudes greater than ice in northern latitudes than Odyssey found last year in southern lati- 85 degrees. The Odyssey data are used to estimate the mass of the tudes,” said Odyssey’s Dr. Igor Mitrofanov of the Russian Space Re- deposit, which can then be compared with the thickness to obtain a By Guy Webster search Institute, Moscow, lead author of a paper in the June 27 issue of density. The dry ice layer appears to have a fluffy texture, like freshly the journal Science. “In some places, the water-ice content is more than fallen snow, according to the report by Dr. William Feldman of Los 90 percent by volume.” Mitrofanov and co-authors used the changing Alamos National Laboratory, N.M., and 11 co-authors. The study also nature of the relief of these regions, measured more than two years ago found once the dry ice disappears, the remaining surface near the pole In winter months, Mars’ icy soil is by the Global Surveyor’s laser altimeter science team, to explore the is composed almost entirely of water ice. covered by a thick layer of carbon implications of the changes. “Mars is constantly changing,” said Dr. Jeffrey Plaut, Mars Odyssey Odyssey’s trio of instruments, the gamma ray spectrometer suite, can project scientist at JPL. “With Mars Odyssey, we plan to examine these dioxide (“dry ice”) frost, identify elements in the top meter (3 feet) or so of Mars’ surface. Mars dynamics through additional seasons, to watch how the winter accumu- obscuring the water ice signature. Global Surveyor’s laser altimeter is precise enough to monitor meter- lations of carbon dioxide on each pole interact with the atmosphere in the current climate regime.” As the layer dissipates in the spring scale changes in the thickness of the seasonal frost, which can accumu- late to depths greater than a meter. The new findings show a correlation Mitrofanov’s co-authors include researchers at the Institute for Space and summer, the water ice in the springtime between Odyssey’s detection of dissipating carbon Research, Russian Academy of Science, Moscow; Massachusetts Insti- becomes ‘visible’ to the neutron dioxide in latitudes poleward of 65 degrees north and Global Surveyor’s tute of Technology; NASA Headquarters, Washington, D.C.; Goddard measurement of the thinning of the frost layer in prior years. Space Flight Center, Greenbelt, Md.; and TechSource, Santa Fe, N.M. and gamma ray detectors “Odyssey’s high-energy neutron detector allows us to measure the Feldman's co-authors include researchers at New Mexico State Universi- onboard Odyssey. Left image thickness of carbon- dioxide at lower latitudes, where Global Surveyor’s ty; Cornell University, Ithaca, N.Y.; and Observatoire Midi-Pyrenees, mosaic shows the northern altimeter does not have enough sensitivity,” Mitrofanov said. “On the Toulouse, France. hemisphere of Mars as seen by the Viking orbiter. The second image shows the concentration of water ice (in blue) observed by Odyssey during the northern winter, when much of it is buried by carbon dioxide frost. Third image shows the water ice that is revealed during the Martian summer. 2 Stardust trajectory modified interstellar dust, will be taken to the Universe JPL’s Stardust spacecraft on June 18 planetary material curatorial facility at Johnson Space Center for examination. Special Events Calendar successfully completed the mission’s third deep-space maneuver. This criti- cal maneuver modified the spacecraft’s Women’s Club offers kids’ activities News The Caltech Women’s Club is spon- Wednesday, July 9 trajectory, placing it on a path to Ongoing Support Groups soring two summertime activities for encounter and collect dust samples Alcoholics Anonymous—Meetings are JPL Amateur Radio Club—Meeting at children from 10 a.m to noon at Tour- from comet Wild 2 in January 2004. available. Call the Employee Assistance noon in Building 238-543. nament Park in Pasadena. Briefs Stardust fired its eight, 4.4-newton Program at ext. 4-3680 for time and Preschool Playgroup for ages 1-4 is JPL Toastmasters Club—Meeting at 5 (1-pound) thrusters for 1,456 seconds, location. changing the comet sampler’s speed by held Tuesdays. The group offers crafts, p.m. in the 167 conference room. Call 34.4 meters per second (77 mph). song and story time, free play and Caregivers Support Group—Meets the Debbie Llata at ext. 3-3690 for infor- “It was a textbook maneuver,” said exploratory learning, and also offers a first Thursday of the month at noon in mation. JPL’s ROBERT RYAN, Stardust’s mission supportive environment for parents and Building 167-111 (The Wellness Place). caregivers to observe and interact with Call the Employee Assistance Program manager. “This was the last big burn Thursday, July 17 we will have prior to our encounter with their child in learning and at play. For at ext. 4-3680. “Staying on Track in a Market Down- Wild 2, and it looks very accurate.” more information, contact JULIA KEN- Codependents Anonymous—Meets at turn”—Scott Budde, TIAA/CREF’s Stardust has traveled more than 2.9 NEFICK at (626) 792-7808 or julia@ astro.caltech.edu. noon every Wednesday. For more director of equity portfolio analytics, billion kilometers (1.8 billion miles) information, call Occupational Health Wednesdays in the Park offers conver- will appear in the 180-101 conference since its February 1999 launch.
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