Mars Climate Orbiter

previous Mars Surveyor 1998 Orbiter

Mars Climate Orbiter, the first of the two Mars Surveyor 1998 spacecraft (the other being the Mars Polar Lander), was successfully launched on December 11, 1998 by a Delta II 7425 launch vehicle. After a more than 9 months long interplanetary cruise, the craft arrived at Mars on schedule, on September 23, 1999, in order to be inserted into Mars orbit. After Mars Orbit Insertion (MOI), the spacecraft was intended to become the first interplanetary weather satellite.

It was planned to go into an initial 160 x 39,000 km orbit, which was to be lowered by aerobraking to 90 x 405 km on November 22, 1999, when an additional rocket ignition should bring the orbiter into its final working orbit, an almost circular polar orbit of 405 km height. Its mission was to do extensive research of Mars' atmosphere, weather and climate, i.e., observe wind, water vapor, volatiles, carbon dioxide budget, clouds etc. Moreover, it should have served as relay for the Mars Polar Lander. It carried a Russian instrument (IR sensor) and was the first in the US-Russian Mars Together cooperative program.

Mars Climate Orbiter finally got lost when it probably came to close to planet Mars during its Mars Orbit Insertion manouver on September 23, 1999. After initiating the MOI apparently successful and on schedule, MCO disappeared behind the planet's limb, as planned. However, it never re-appeared, and ground control waited in vain for signals after the craft should have come out of the radio shadow. [ see JPL Press Release]

It was soon found that the spacecraft had probably come too deep into Mars atmosphere, because it had been erroneously navigated on a trajectory bringing it down to only 50 km above surface, and was very probably destroyed - its safe altitude would have been about 80 km (50 miles). The error was caused because of a confusion of metric and imperial units between different collaborating teams.

[MCO pic of Mars]

Shortly before completing its cruise, on 7 September 1999 at about 16:30 UTC, Mars Climate Orbiter had taken one single image of the target planet. [ More info on this image, MSSS]


Hartmut Frommert [contact]

[Mars] | [Spider] @ [SEDS]

Last Modification: October 11, 1999