Mars Climate Observer

Credit: NASA

The second launch of three in the 1998-99 launch window was of the Mars Climate Orbiter (MCO; formerly the Mars Surveyor '98 Orbiter), the second of three spacecraft in the Mars Surveyor program, the first being Mars Global Surveyor (launched in November 1996) and the third being the Mars Polar Lander (formerly the Mars Surveyor '98 Lander). MCO was designed to arrive at roughly the same time as Mars Polar Lander and conduct simultaneous investigations of Mars's atmosphere, climate, and surface. MCO was also designed to serve as a communications relay for the Mars Polar Lander and other future NASA and international lander missions to Mars.

After the Lander's three-month mission, MCO would have performed a two-year independent mission to observe and study dust storms, weather systems, clouds and dust hazes, ozone, distribution and transport of dust and water, the effects of topography on atmospheric circulation, atmospheric response to solar heating, and surface features, wind streaks, erosion, and color changes. It would also take daily pictures of the planet's surface to construct an evolutionary map of climatic changes. Scientists hoped that such information would aid in reconstructing Mars' climatic history and provide evidence of buried water reserves.

MCO was launched on December 11, 1998 by a Delta 7425 rocket. The spacecraft reached Mars on September 23, 1999, and executed a 16 minute, 23 second orbit insertion main engine burn. MCO passed behind Mars and was to re-emerge and establish radio contact with Earth 10 minutes after the burn was completed. However, contact was never re-established and no signal was ever received from the spacecraft. Findings of the failure review board indicate that a navigation error resulted from some spacecraft commands being sent in English units instead of being converted to metric. This caused the spacecraft to miss its intended 140 - 150 km altitude above Mars during orbit insertion, instead entering the Martian atmosphere at about 57 km. The spacecraft would have been destroyed by atmospheric stresses and friction at this low altitude.

The above photograph is one of the very few taken by MCO, and was the first photograph of Mars taken by the MCO's Mars Color Imager (MARCI). The photograph was taken on September 7, 1999 when the spacecraft was approximately 4.5 million km (2.8 million miles) from the planet. This full-scale medium angle camera view is the highest resolution possible at this distance from Mars.