Mars Climate Orbiter
Mars Climate Orbiter — a NASA orbiter launched on 11 December 1998 to study the weather and climate of Mars. On 23 September 1999 it began its orbit-insertion burn, passed behind Mars 49 seconds earlier than predicted and was never heard from again. It had come in far too low, about 57 km above the surface, because a ground software file gave its thruster data in imperial units (pound-seconds) where the navigation software expected metric ones (newton-seconds). The investigation board concluded that it was either destroyed in the atmosphere or went back out into orbit around the Sun. (Its position here is representative.)
Key facts
Mission & specifications
Mission
- Operator
- NASA / JPL
- Launched
- December 11, 1998
- Status
- Lost
Trajectory
- Distance from the Sun
- 1.58 AU
- Computed from the cached position
- Distance from Earth
- 1.53 AU
- Computed from cached positions
- Distance from Mars
- 1,948,076 km
- Computed from cached positions
Mission
Mars Climate Orbiter was one of the two spacecraft of NASA's Mars Surveyor '98, with Mars Polar Lander, built by Lockheed Martin Astronautics. It was to watch the weather of Mars every day, measure the water vapour and dust in its atmosphere, look for evidence of past climate change and relay the lander's signals. It was launched from Cape Canaveral on 11 December 1998 at 18:45 UTC on a Delta II, a 7425 by NSSDCA and the investigation board (a 7427 in NASA's history Beyond Earth). On 23 September 1999 its engine started at 09:00:46 UTC to put it into orbit. At 09:04:52 it passed behind Mars, 49 seconds earlier than predicted, and was not heard from again; the search went on until 25 September. The reconstruction showed it had come in about 170 km lower than planned, about 57 km above the surface, while 80 km was judged the lowest survivable height. (Against a different target, NSSDCA gives the miss as 80 to 90 km.) The board's root cause was the failure to use metric units in a ground software file, "Small Forces", used in the trajectory models: it gave the effect of the craft's small thruster firings in pound-seconds where the navigation software expected newton-seconds, so they were misjudged throughout the cruise. The board concluded that the spacecraft either was destroyed in the atmosphere or left it again into orbit around the Sun.
- 1998Mars Climate Orbiter launches toward Mars on a Delta II rocketLaunch
It comes in far too low, because a ground software file used imperial units.
Images
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