At 09:01 UT (5:01 a.m. EDT), Thursday, 23 September 1999 Mars Climate Orbiter (MCO) fired its main engine to begin its insertion into Mars orbit. Five minutes later the spacecraft was occulted by Mars (went behind Mars as seen from Earth) and the signal was lost as planned. Telemetry up to this point indicated that the spacecraft was functioning normally. Communication with MCO was scheduled to be reacquired about 20 minutes later, at 09:25 UT, when the spacecraft was to have reappeared from behind Mars. However, no signal was received at that time and further search for a signal has so far proved fruitless.
Careful examination of the last 6 to 8 hours of pre-orbit insertion telemetry and flight data indicated that a significant navigation error may have been made and that Mars Climate Orbiter had flown over Mars at an altitude of only 60 km instead of the planned 150 km. The spacecraft was designed to withstand incursions into the martian atmosphere down to an altitude of about 85 km, below that MCO would probably break up from atmospheric stresses. The data is still being examined but if MCO did indeed enter Mars atmosphere at 60 km atmosphere it was almost certainly destroyed. At a press briefing at JPL at 15:00 UT (11 a.m. EDT, 8 a.m. PDT) it was announced that a team had been formed to study the situation and determine the reason for the loss of contact and if it is due to a navigation error, the cause of the error.
According to the telemetry, MCO appeared to be on course for its flight over Mars at the intended 150 km altitude after the final trajectory correction maneuver on 15 September and as late as 24 hours before the orbital insertion burn, but further examination of the data may reveal that the knowledge of its location was incorrect. There is no speculation on the source of the navigation error, but there is currently no sign that there was any problem with the spacecraft systems. Mars Climate Orbiter was scheduled to act as a relay for the Mars Polar Lander mission, scheduled to land in December, but the loss of MCO will not significantly affect the lander science return because Mars Global Surveyor can act as a relay and the lander is also capable of transmitting data directly to Earth, albeit at somewhat slower data rates.
In addition to its role as a relay, Mars Climate Orbiter was
also equipped with two science instruments, a camera to study
weather and climate on Mars and the Pressure Modulated
Infrared Radiometer, or PMIRR, to study atmospheric properties.
The PMIRR was a replacement for the instrument on the Mars
Observer mission which was lost in 1993 before it reached Mars.
Mars Climate Orbiter was launched in December 1998 and was
scheduled to study Mars from polar orbit for one martian year
Press Release from JPL:
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
FOR IMMEDIATE RELEASE - September 23, 1999
NASA'S MARS CLIMATE ORBITER BELIEVED TO BE LOST
NASA's Mars Climate Orbiter is believed to be lost due to a suspected navigation error.
Early this morning 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.
The report of the failure review board investigating the loss of Mars
Climate Orbiter was discussed at a press briefing on Wednesday,
November 10, 1999. The findings and recommendations of the review board
are detailed in a
NASA Press Release.
Mars Climate Orbiter
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