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Planetary News: Phoenix (2008)Phoenix Lands Flawlessly on Mars and Sends Home First PostcardsBy A.J.S. Rayl
PASADENA -- Phoenix has landed on Mars. After traveling for 10 months on a 422-million-mile route, the spacecraft landed right on time in the northern arctic plains of Mars, at 68 degrees north, near the polar cap, just before 5 pm Pacific Daylight Time (PDT). And the first images are already in. The signal confirming Phoenix's arrival on the surface of Mars came into NASA's Jet Propulsion Laboratory (JPL) at 4:53 pm Pacific Daylight Time / 7:53 pm EDT / 11:53 pm UTC. The landing actually happened about 15 minutes earlier on Mars, but at the current distance between Mars and Earth, about 172 million miles, it takes 15 minutes for the radio signal confirming the spacecraft's arrivial to get "home." About two hours after confirmation came through that Phoenix landed, the engineering and terrain images the team instructed the spacecraft to take came int to the Jet Propulsion Laboratory (JPL) and the University of Arizona Phoenix Science Operations Center. They show the solar arrays fully deployed and some of the patterned arctic terrain around Mars' north pole. Phoenix joins NASA's Mars Exploration Rovers, Spirit and Opportunity, on the surface. Phoenix'sentry, descent, and landing -- or the "seven minutes of terror" -- as it's been called, looked to be textbook all the way down. The Phoenix flight operations team was able to maintain the signal of the spacecraft all the way down to the surface, as they had hoped they would be able to do. The spacecraft, it was reported, landed tilted at one-quarter of a degree. In other words, it appears to have been a near flawless landing. Could it have possibly gone any better? "Not in my dreams," smiled Barry Goldstein, Phoenix project manager of JPL. Phoenix is about to become the world's first mission to make direct measurements of water on another planet and the first to dig below the surface of the Martian arctic and sample water-ice. "We have to make sure the spacraft is healthy, but by gosh, it's landed in a place where it's almost horziontal to the surface, tilted a quarter of a degree," enthused Peter Smith, principal investigator from the University of Arizona, just after the landing. "It's not on a rock. It's on a nice flat place, very safe and happy."
Smith is not only looking forward to 90 days of "great science," he's looking forward now to "maybe an extended mission." Once Phoenix separated from the backshell and turned on its retro rockets, 12 pulsed thrusters, each putting out 68 pounds of thrust, slowed and guided it to the surface and from the initial telemetry it appears that the spacecraft actually did pirouette down to the surface, according to Goldstein. Phoenix next opened its solar arrays, deployed its camera and weather station mast, and then began taking images. The pictures taken right after landing, which included images of the solar arrays and a few pictures of the arctic landscape, arrived about two hours after confirmation of the landing. Throughout the mission, images will be released to the public as they come through the Deep Space Network (DSN) pipeline, Smith said. In landing, Phoenix delivered a special message from Earth, a silica glass mini-DVD provided by The Planetary Society that contains more than 250,000 names and a collection of Mars-related literature, art, and audio called Visions of Mars. The disk, designed to last hundreds of years, is sent with the hope that future explorers may one day find the message. From its solitary position in the polar arctic, Phoenix will use its 7.7-foot robotic arm to dig for the first time ever into the ice-rich permafrost and scoop up samples of soil and water-ice from beneath the surface, bring them back to the spacecraft for analysis.
It is slated to spend three months investigating the history of the water in the polar ice, looking into whether the subsurface environment in the far-northern plains of Mars has ever been favorable for sustaining microbial life, and assessing the biological potential of the ice-soil boundary. Phoenix also boasts a Canadian-supplied weather station and will be studying the weather in Mars' arctic region. Coordinated observations are planned with the orbiters above to get a top-down analysis of the polar atmosphere. Phoenix is a lander, not a rover like Spirit and Opportunity, and its mission is tightly focused on the target of water-ice that will lie just beneath it and all around it, and it is just as important to furthering NASA objectives. Smith likened Phoenix's purpose to a quote from Ralph Waldo Emerson he saw hanging in the office of JPL Director Charles I. Elachi earlier that morning: "Do not follow where the path may lead. Go, instead, where there is no path and leave a trail." "To go where there is no path and leave a trail for others to follow. That's what Phoenix is doing," Smith said. "We're going where there is no path and we're going to leave a trail for others to follow -- not literally a path, but we're going to a place on the planet unexplored," he qualified. "The polar region on the Earth after 100 years of scientific investigation is known to be a place where quiet records are preserved and where you can find a lot of information about the history of life on Earth," Smith continued. "It is preserved in the ice, the deep freezer of the Earth and perhaps this is true of Mars, too. This is what we're going to be finding out."
By analyzing the chemistry and mineralogy of the soil and ice using robust instruments, scientists will better understand the history of the Martian arctic and determine whether or not it is habitable. "And that is the business of the Phoenix mission, Smith said. Finding life, if any should exist, will be up to another mission, because they don't have the instruments onboard to detect microscopic life. If, however, there should be sizeable "bugs," clearly their cameras would image them. Part of larger NASA program to look for life on Mars, Phoenix will provide an important contribution to the agency's "Follow the Water" science strategy and will be instrumental in achieving the four science goals of NASA's long-term Mars Exploration Program: 1) determine whether life ever arose on Mars; 2) characterize the climate of Mars; 3) characterize the geology of Mars; and 4) prepare for human exploration. Beyond being the world's first Martian arctic explorer, Phoenix is the first NASA mission being led by a public university and the University of Arizona has the honors. Mission operations are expected to roll over to Arizona's Phoenix Space Operations Center once the spacecraft has landed, stretched out it solar array "wings," and tested its long robotic arm. That shift is expected to occur on Wednesday, May 28. The landing came less than three hours after the famed Indy 500 race ended at the Indianpolis Motor Speedway. If Phoenix had been racing, it would have finished first, in 2.5 minutes. For more information, log back on as coverage of Phoenix flight continues, and be sure to check out Emily Lakdawalla's Planetary Society Planetary Weblog. General Timeline for Phoenix Mission OperationsEvent times are given in Spacecraft Event Time
(SCET), which is the time according to the spacecraft's clock, and also
Earth Received Time (ERT), which accounts for the 15 minutes and 20 seconds
it takes radio signals to traverse the 275 million kilometers (171 million
miles) separating Earth and Mars on landing day. ERT is given both in Universal
Time (UTC) and Pacific Daylight Time (PDT).
The first week following landing will be a "characterization phase," during which the instruments and systems will be ckecked out and tested. Approximately one week after landing, the digging phase will begin, and the first sample of surface soil will be delivered to the Thermal and Evolved-Gas Analyzer (TEGA) instrument. The first analyses will take 10 to 15 days. At the same time as the instruments are being checked out, a parallel effort will be undertaken to determine exactly where Phoenix landed. An approximate location will be known within hours of landing, and two Mars Reconnaissance Orbiter HiRISE images will be taken. However, the knowledge of the location of Phoenix may not be good enough to steer the targeting of HiRISE on the first day. Another imaging attempt planned for the fifth day is more likely to be successful. Digging will proceed in several cycles lasting 8 to 15 days apiece. After each two to three centimeters of digging, new samples will be delivered to TEGA and to the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA). The nominal mission plan accounts for a total of seven cycles of digging and analysis. It is unknown how far Phoenix will have to dig to reach ice, but it is epected to be about two to five centimeters. If the ice is found at the deeper end of the range, the first ice samples may not be analyzed until July or later. The digging phase is expected to last until the beginning of September, 90 sols after landing. Once the digging phase is over, Phoenix will continue to operate essentially as a polar weather station. The mission will end when the Sun travels low enough in the sky that Phoenix no longer receives sufficient power. The spacecraft will conserve power as long as possible. The cameras will search for the first carbon dioxide frost deposits while the Meteorological Station (MET) instrument monitors the weather conditions. The northern autumnal equinox will arrive on Mars on December 26, 2008, bringing winter darkness to the north pole. Phoenix will not survive past this date. In fact, it may not survive beyond November. Emily Lakdawalla contributed this Timeline to this report. For the Phoenix Mars Mission home page, go to: http://phoenix.lpl.arizona.edu/ NASA TV will cover the Phoenix landing events. For information on how to connect: http://www.nasa.gov/multimedia/nasatv/index.html
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