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Reassessed fuel measurements give Mars Odyssey until 2025 before it runs out

Using more refined methods for measuring the fuel left on Mars Odyssey, the oldest orbiter circling Mars at this time, engineers have determined that it will not run out until 2025, not this year as previously thought.

Mars Odyssey has been in orbit around Mars since 2001. The fuel is used by thrusters to help maintain the spacecraft’s orientation, which is mostly done by reaction wheels, or gyroscopes. We should therefore not be surprised if by 2025 engineers figure out a way to get the reaction wheels to do the whole job, when the fuel runs out.

Conscious Choice cover

Now available in hardback and paperback as well as ebook!


From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.

Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.  
Conscious Choice does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.


“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.


All editions are available at Amazon, Barnes & Noble, and all book vendors, with the ebook priced at $5.99 before discount. The ebook can also be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner.


Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95; Shipping cost for either: $5.00). Just email me at zimmerman @ nasw dot org.


  • Richard M

    That said, it’s high time we get some more assets to Martian orbit, for communications relay from surface missions if nothing else.

    I wonder if the private sector might have some low cost solutions for us here?

  • Nick B.

    They’d still need a way to dump momentum periodically. Maybe they can get very creative with solar torque or something, but that may not be enough.

  • geoffc

    @Richard M: How long till we get Starlink for Mars from SpaceX? :) With a few relay satellites…

  • Richard M

    Hello geoffc,

    1. I like the way you think, though of course Starlink would require some substantial modifications to function successfully in Mars orbit…
    2. SpaceX should call any network it deploys there “Marslink.” :)

  • Edward

    For a while, I worked a couple of cubicles away from a thermal engineer who did these kinds of propellant tank measurements. Pulse some heat and see what temperature it reaches and how long it took to get there. It was interesting to read the article, which pointed out a flaw and the correction in that method, at least for this particular spacecraft.

    The reaction wheels already do most of the work for attitude control for these kinds of three-axis stabilized spacecraft,* but there can be torques on the spacecraft that spin up the reaction wheels as they counteract those torques, and as it orbits Mars it points one side continuously toward the planet, meaning that the spacecraft is continuously rotating, which requires the reaction wheels to constantly speed up. When their speed reaches a certain amount, the thrusters are fired in order to put a torque that causes the reaction wheels to spin-down until their speed is much more acceptable. Once the propellant for de-spinning the reaction wheels runs out, I think it is unlikely that Mars Odyssey will be able to keep that one side pointed toward Mars for long.

    Attitude control and station keeping propellants are two reasons for satellites having a definite lifetime, but solar arrays also degrade with time, due to the ultraviolet light from the sun. These three factors give an amount of predictability for calculating an expected lifetime, but degradation in various other parts can have predictable or unexpected affects on lifetime, too.
    * Geostationary communication and weather satellites are three-axis stabilized, too. They, too, keep one side, called the Earth Deck, facing the Earth, and this deck would carry antennas, cameras, and other sensors that needed to face the Earth.

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