This Week in Space History: Mars Observer

Sep 24, 2022 | Daily Space, Mars, NASA, Space History

This Week in Space History: Mars Observer
IMAGE: Titan III vehicle launched the Mars Observer spacecraft and the Transfer Orbit Stage (TOS) from the Cape Canaveral Air Force Station on September 25, 1992. CREDIT: NASA

This week in space history: NASA’s Mars Observer.

Mars Observer started in the mid-1980s under NASA’s program of Faster Better Cheaper missions. Before Mars Observer, the last mission to Mars was Viking in 1976. The mission was designed in response to a decadal survey request for a small mission focused on Mars’ atmosphere and surface over a full Martian year.

Unfortunately, Observer ended up being neither faster, better nor cheaper. Instead, it ended up being one of many failed Mars missions NASA launched in the 90s.

The spacecraft was supposed to be basically off the same production line as a communications satellite going to geostationary Earth orbit. A key difference from NASA missions before or since is that the spacecraft was designed prior to the instruments – most science missions are designed the other way around. Another key change was the instruments themselves: they were supposed to be existing designs operated by experienced science teams.

However, none of those things ultimately happened, as a major imaging system was added late in the process, and the science instruments ultimately chosen had less “heritage” or knowledge on how they would perform and they would be operated by first-time investigators. This meant that the spacecraft had to be modified more than anticipated to accommodate these instruments. And the instruments brought with them a huge solar panel and a 1.5-meter diameter communication antenna.

Mars Observer was launched on a commercial rocket, the Commercial Titan III. The CT-3 was a version of the Titan 34D originally used to launch huge imaging satellites for the military.

IMAGE: In the Payload Hazardous Servicing Facility, the integrated Mars Observer/Transfer Orbit Stage (TOS) payload is ready for encapsulation in the Titan III nose fairing. CREDIT: NASA

Mars Observer was launched on September 25, 1992, and by all accounts worked very well during its cruise to Mars, with only a few minor problems. It even took a few pictures of Mars about a month before it would perform its Mars orbit insertion. Three days before Mars orbit insertion, on August 22nd, 1993, contact with the spacecraft was lost. Despite three months of attempts, it was never re-established.

After attempts to regain contact were exhausted, NASA, JPL, and the spacecraft manufacturer each set up their own review boards.

None of the review boards came up with a definitive reason for the failure. The most probable cause was a leak in the fuel tanks during preparation for Mars orbit insertion that spun the spacecraft out of control and ripped it to pieces. According to the original plan, pressurization of the fuel tanks should have been done a month after launch, but it was moved to three days before insertion because of the risk of accidentally bursting the tanks before that point. The main engines were used before insertion but got their propellant via a different connection.

Mars Observer had a significant legacy despite its failure – it led to the more structured Mars Surveyor Program. Besides the technical lessons about spacecraft design and operation, NASA finally accepted that science spacecraft will never be cheap or mass-produced, and they need better risk assessments for projects as a whole.

The Mars Surveyor Program was a series of small missions launched during every possible launch window every 26 months. Both missions from the 1998 launch window failed, finally leading to the end of the Faster Better Cheaper program.

Duplicates of Mars Observer’s instruments were flown on the next orbiters NASA sent to Mars: Mars Global Surveyor, Mars Climate Orbiter (which also failed but for a different reason), Mars Odyssey, and Mars Reconnaissance Orbiter. Except for Mars Climate Orbiter, which never made it to Mars, and Mars Global Surveyor, which was retired after ten years, all are still in operation around Mars.

One last footnote, the launch of Mars Observer ended up being the final Commercial Titan III launch. Martin Marietta lost the government contract the rocket was designed for and it was more expensive than other commercial rockets at the time, so they only managed 4 launches. However, the rocket that did win that government contract to launch GPS satellites was McDonnell Douglas’s Delta II, which went on to launch many important payloads for NASA.

More Information

The Tragedy of Mars Observer,” Glenn E. Cunningham, 2017 July 7, IFAC Proceedings Volumes

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