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NASA Mars Odyssey Orbiter Fuel Supply Running Low

NASA's Mars Odyssey Orbiter has been studying the Red Planet for the past 22 years, but the orbiter is approaching the end of its mission as its running low on fuel.

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Zac Aubert

Zac Aubert

Wed Mar 15 2023Written by Zac Aubert

NASA's Mars Odyssey Orbiter has been studying the Red Planet for the past 22 years, but the orbiter is approaching the end of its mission as its running low on fuel.

The Odyssey Orbiter was launched in April 2021, arriving at Mars in October 2001. Since then the orbiter has orbited Mars more than 94,000 times, covering about 1.37 billion miles (2.21 billion kilometers) providing invaluable data on minerals, ice deposits, and radiation on the planet, in addition to scouting potential landing sites for future missions.

The Odyssey spacecraft is powered by solar panels, but it also carries a fuel supply of hydrazine, which is used to adjust its orbit and keep it stable. However, there is no fuel gauge on board the spacecraft, which makes it challenging to estimate how much fuel is left. Engineers have used various methods to calculate the amount of fuel remaining, such as measuring changes in the spacecraft's velocity and monitoring the pressure in the fuel tanks.

In summer of 2021, an estimate of Odyssey's fuel supply indicated that the spacecraft had only 11 pounds (5 kilograms) of hydrazine left, which was lower than the mission's modeling had predicted. The estimate was based on a method that involved heating the spacecraft's propellant tanks and measuring how long they took to reach a certain temperature. To confirm the estimate, the mission team conducted further tests and investigations to better understand the behavior of the spacecraft's fuel system.

In January 2022, the results showed that only 6 pounds (2.8 kilograms) of hydrazine remained, indicating that the spacecraft would run out of fuel in less than a year.

However, after months of testing and investigation, the mission engineers discovered that the complex fuel system of the aging spacecraft behaved differently than expected, and their new calculations indicated that Odyssey still had enough fuel to last until at least the end of 2025.

This discovery is significant for the scientific community as the Odyssey spacecraft has been a vital part of NASA's Mars exploration program for over two decades, providing valuable data and helping to advance our understanding of the Red Planet. The spacecraft's extended lifespan will allow it to continue its mission and make even more important discoveries in the years to come.

How Odyssey Uses Hydrazine

Odyssey relies primarily on solar panels to power its systems and three strategically placed reaction wheels to orient its scientific instruments toward the Martian surface. As the reaction wheels spin, they generate torque that causes the spacecraft to move in the opposite direction. Maintaining the spacecraft's pointing requires coordinated operation of the reaction wheels.

Since Odyssey completes a full loop every orbit, it needs a mechanism to discharge the growing momentum. Odyssey's hydrazine propulsion system serves this purpose by releasing small, precise bursts of propellant to counterbalance the momentum generated by the reaction wheels. "The reaction wheels and hydrazine system work in tandem to keep the spacecraft on course" - Jared Call, Mission Manager of Odyssey at NASA's Jet Propulsion Laboratory in Southern California

Odyssey Launch

The Mars Odyssey Orbiter was launched on April 7, 2001 aboard a ULA Delta II as part of NASA's Mars Exploration Program. It arrived at Mars on October 24, 2001, and has been orbiting the planet ever since, making it one of the longest-running spacecraft in Mars orbit. The spacecraft was designed to study the planet's geology, radiation, and mineral resources, and to serve as a communication relay for other spacecraft on the surface.