Early in the morning of Sept. 23, at about 2 a.m. Pacific Daylight Time, the orbiter fired its main engine to go into orbit around the planet. All the information coming from the spacecraft leading up to that point looked normal. The engine burn began as planned five minutes before the spacecraft passed behind the planet as seen from Earth. Flight controllers did not detect a signal when the spacecraft was expected to come out from behind the planet.

"We had planned to approach the planet at an altitude of about 150 kilometers (93 miles). We thought we were doing that, but upon review of the last six to eight hours of data leading up to arrival, we saw indications that the actual approach altitude had been much lower. It appears that the actual altitude was about 60 kilometers (37 miles). We are still trying to figure out why that happened," said Richard Cook, project manager for the Mars Surveyor Operations Project at NASA's Jet Propulsion Laboratory. "We believe that the minimum survivable altitude for the spacecraft would have been 85 kilometers (53 miles)."

"If in fact we have lost the spacecraft it is very serious, but it is not devastating to the Mars Surveyor Program as a whole. The program is flexible enough to allow us to recover the science return of Mars Climate Orbiter on a future mission. This is not necessarily science lost; it is science delayed," said Dr. Carl Pilcher, science director for Solar System Exploration at NASA Headquarters, Washington, D.C. "We have a robust program to explore Mars that involves launching on average one mission per year for at least a decade. It began with the launch of Mars Pathfinder and Mars Global Surveyor in 1996, continued with Mars Climate Orbiter and Mars Polar Lander and will be followed by more missions in 2001, 2003 and 2005. In fact, Mars Polar Lander will arrive in just over two months and its mission is completely independent of the Mars Climate Orbiter. The science return of that mission won't be affected."

Flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, CA and Lockheed Martin Astronautics in Denver, CO will continue their efforts to locate the spacecraft through the Deep Space Network during the next several hours. A special investigation team has been formed by JPL to further assess the situation.

Mars Climate Orbiter is one of a series of missions in a long-term program of Mars exploration known as the Mars Surveyor Program that is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.

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