As part of NASA’s long-term plan for the exploration of Mars, the Mars Climate Orbiter and the Mars Polar Lander were scheduled to arrive in late 1999. Their primary purpose was to study the Martian climate and to collect evidence of climatic change, which might have provided evidence of life on the planet as well as the extent of its resources. Unfortunately, both missions failed.
The exploration of Mars had long been a problematic business before the launch of the Mars Climate Orbiter and the Mars Polar Lander. The first few Soviet attempts to send spacecraft to Mars failed, as did the U.S. Mariner 3, launched in November, 1964, although its sister craft Mariner 4 flew past the planet in July, 1965. Mariner 8 also failed, although Mariners
The renewed Mars Surveyor Program suffered an early setback when the Mars Observer Orbiter failed in 1992, but it got back on track when the Mars Global Surveyor,
The Mars Climate Orbiter was a box-shaped device measuring approximately 2.1 meters by 1.6 meters by 2 meters, with a launch mass of 629 kilograms. It was designed to function as an interplanetary weather satellite and communications relay for the Mars Polar Lander. It carried two scientific instruments: a duplicate of an atmospheric sounder that had been included in the Mars Observer Orbiter’s equipment and a lightweight color imager combining wide- and medium-angle cameras.
The Climate Orbiter reached its target on September 23, 1998, but contact was lost on September 24. A board of inquiry—under the chairmanship of Arthur Stephenson, the former director of the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center in Huntsville, Alabama—was immediately set up to investigate what had gone wrong; the conclusion was soon reached that the craft had burned up in the Martian atmosphere. On September 30, the board reported preliminary findings indicating that the satellite, which had been intended to take up an orbit between 140 and 150 kilometers above the surface, had actually received instructions to place itself in an orbit 57 kilometers above the surface, deep enough within the atmosphere to be destroyed by frictional heat.
The board established that this error had occurred because engineers at Lockheed Martin Engineering, who had supplied some of the satellite’s equipment, had been working in imperial measurements (pounds and inches) rather than the metric units (kilograms and centimeters) employed by NASA, and their figures had not been converted at NASA’s Jet Propulsion Laboratory
The failure of the Mars Climate Orbiter increased the intensity of anxiety regarding its sister mission. The Mars Polar Lander had a cylindrical core equipped with three aluminum legs and a robot arm; it stood 1.06 meters tall and was 3.6 meters wide. Its launch mass was 583 kilograms. It carried various instruments for reporting meteorological conditions, analyzing polar deposits and soil samples, and obtaining multidimensional images of surface formations. It was supplemented by the Deep Space 2 surface-penetrator. The Polar Lander was supposed to touch down one thousand kilometers from the planet’s south pole, in Planum Australe, on the edge of the ice cap.
Illustration of the Mars Climate Orbiter before it was to go into orbit around Mars.
The last information sent back by the Polar Lander was transmitted immediately prior to its entry into the atmosphere on December 3, 1999. No further signals were received. The Mars Global Surveyor, which had been fully operative since March, was rerouted to carry out an intensive search, in case the Polar Lander had reached the surface before malfunctioning, but no trace of it was found. In the meantime, the two project managers, Richard Cook and John McNamee, attempted to figure out what might have gone wrong. They eventually concluded that the most likely explanation was a software error that had misinterpreted vibration caused by deployment of the lander’s legs as the touchdown, resulting in the thrusters (which were supposed to soften the landing) cutting out while the craft was still forty meters above surface. The most likely alternative seemed to the investigators to be the deterioration of the hydrazine fuel used in the thrusters, but no firm proof was obtained of either conjecture, so the matter remained unsettled.
The double failure of the 1999 mission was a serious setback for NASA’s Mars Surveyor Program, the loss of the second craft augmenting and reemphasizing the embarrassment of the seemingly silly error that had caused the loss of the Climate Orbiter. Fortunately, the Global Surveyor continued its mission to map Mars from low altitude, completing its original schedule on January 31, 2001, and contact with the satellite was maintained until November 2, 2006. Additionally, the Mars Pathfinder landed in July, 1997, in Ares Vallis in the northern hemisphere, and its rover sent back a great many pictures during the next two months—the first images sent from the surface since those transmitted by the Soviet Lunokhod rovers twenty years before.
The Soviet program had suffered so many mishaps before and after the Lunokhod mission that it had effectively been abandoned. Other explorers fared no better: The Japanese Nozomi orbiter had failed in 1998, and the European Space Agency’s Beagle 2 lander was lost on entry to the Martian atmosphere in 2003. Still, NASA had always considered itself a cut above the competition, so those failures did not provide much solace for the apparent magnitude of its own, even though the other incidents served as sharp reminders of the enormous difficulties involved in sending spacecraft to Mars. It was not until the Mars Exploration Rover mission successfully landed its twin rovers in 2003-2004—and then recovered communication with the image-overloaded Spirit rover after a temporary loss—that NASA appeared to be back on the progressive track.
The gap left in human understanding of Mars by the loss of the Climate Orbiter and the Polar Lander was only partially filled in by the Mars Exploration Rover mission, and some of the instrumentation carried by the Mars Polar Lander was replicated in the ironically named Phoenix lander, scheduled to arrive on Mars in 2008.
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Euler, Edward A., Steven D. Jolly, and H. H. Curtis. “The Failures of the Mars Climate Orbiter and Mars Polar Lander: A Perspective from the People Involved.” In Proceedings of the Twenty-Fourth Guidance and Control Conference. Breckenridge, Colo.: American Astronautical Society, 2001. Comprehensive retrospective summary of what went wrong with the two missions. -
Godwin, Robert, ed. Mars: The NASA Mission Reports. 2 vols. Burlington, Ont.: Apogee Books, 2004. Two-part omnibus making NASA’s reports more widely available and placing the unfortunate history of the Mars Climate Orbiter and the Mars Polar Lander in the wider context of Mars exploration. -
Squyres, Steve. Roving Mars: Spirit, Opportunity, and the Exploration of the Red Planet. New York: Hyperion, 2005. Provides a succinct overview of the history of Martian exploration in a reader-friendly fashion, with elaborate commentary.
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