Space Exploration: Loss of Mars Polar Lander Deals NASA Another Blow – Encarta Dec 99 update
For the second time in three months, an American mission to Mars was lost when the Mars Polar Lander suffered an unknown malfunction on December 3, 1999. It was the second such incident in the last three months for the National Aeronautics and Space Administration (NASA), prompting a complete internal reevaluation of the agency's planetary exploration program.
According to NASA officials, the spacecraft was on course and functioning normally when it went into landing mode as scheduled on December 3. But the Polar Lander never sent another signal, and after four days of tense monitoring, the officials declared the $165-million mission dead.
Engineers said they were unsure what went wrong with the lander. Possible scenarios include problems when the lander separated from a vehicle or malfunctions in the lander's parachute, propulsion system, or radar. The mission could even have been thwarted by a stroke of terrible luck, such as the lander setting down on a rock or in a crevice. Because the craft was designed to send out no data while it landed—an economy measure—officials say they will probably never discover what happened to Mars Polar Lander.
The mission was designed to touch down in the south polar region of Mars and investigate the water content of the planet's soil, which would give strong clues as to whether the planet ever supported life. The spacecraft also carried two experimental probes that were designed to crash into the Martian surface at high speed and bury sensors in the ground, where they would analyze the soil and collect data. NASA officials heard nothing from these probes either.
The loss was a further embarrassment for NASA after the similar fate of the Mars Climate Orbiter, the lander's sister spacecraft, which vanished just as it reached the red planet on September 23, 1999. An investigation revealed that the orbiter probably burned up as it entered the atmosphere of Mars because of a miscalculation. The error was later traced to a mix-up of English and metric units between the orbiter's operator, the Jet Propulsion Laboratory of Pasadena, California, and the contractor that built it, Lockheed Martin Corporation of Bethesda, Maryland. (For more on the loss of the orbiter, see the September 1999 Update “Mars: Spacecraft Sent to Study Climate Presumed Destroyed.”)
These recent incidents were not the first time NASA has had trouble with missions to the fourth planet from the Sun. At its closest point to Earth in its orbit, Mars is still 55.7 million km (34.6 million mi) away. In 1993 the agency suffered a huge blow when the $1-billion Mars Observer disappeared just before it was to enter Mars orbit. The United States is the only nation that has successfully placed a spacecraft on Mars, landing the Viking probes in the mid-1970s and the Mars Pathfinder in the mid-1990s. The failures have been numerous, including six by the former Union of Soviet Socialist Republics (USSR).
Even more troubling for NASA were the investigation's findings that both the Climate Orbiter and Polar Lander missions suffered from poor team training, understaffing, inadequate safeguard procedures, and communication problems. The two mission failures and follow-up findings compelled NASA officials to review their entire Mars program for possible changes, including the planned 2001 launches of another orbiter and another lander. The program was supposed to culminate in the delivery of Martian rock and soil samples to Earth in 2008.
The NASA strategy of sending up a number of smaller missions came about after the giant Mars Observer mission failed. Spread the risks out while keeping costs down, the thinking went, according to NASA administrators. Known by the motto “faster, better, cheaper,” the strategy worked well with the successful Pathfinder and Mars Global Surveyor 96 missions. But some experts, both within NASA and outside the agency, now question the policy, suggesting that the agency possibly has cut too many corners in its attempt to keep costs low.
The Global Surveyor has been orbiting the red planet since 1997, providing data to scientists. It was even used to try to find the Polar Lander, with no apparent success. Some of the surveyor's data was the basis for the December 10 report in the journal Science that a huge ocean once existed in the northern hemisphere of Mars.
According to the report, produced by a team of scientists at Brown University in Providence, Rhode Island, the data show evidence of an ancient coastline. This finding provides more solid backing for a theory previously advanced by other planetary geologists that Mars harbored a huge ocean several billion years ago.
The official Web site of the Mars Polar Lander offers photographs, drawings, and facts about the mission. The Mars Global Surveyor site provides more information about its mission, including data from the Science report on the ancient ocean evidence. The sites of the NASA Mars Exploration Program and the Center for Mars Exploration offer information and updates about all the NASA missions to Mars.
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