Space

Underfunding Phobos-Grunt

12 Comments

…was the cause of the failure. Ultimately, I suppose so. But I’m not sure about this:

On the positive side, Phobos-Grunt’s aluminum fuel tank holding 8.3 tons of toxic fuel is likely to safely burn up during re-entry. “Aluminum has a very low melting temperature and rarely survives,” says space debris expert Nicholas Johnson of NASA’s Johnson Space Center in Houston.

That’s assuming that the propellant isn’t frozen. Do we know that?

12 thoughts on “Underfunding Phobos-Grunt”

  1. Has anyone taken observations on Phobes/Grunt to determine if it is stable or tumbling? If it’s tumbling, then it’s dead so there’s a good chance the propellant is frozen. If it’s stable, then the solar panels might be providing enough power to keep things liquid. IIRC, there were reports after launch that the probe was stable so perhaps it was a failure of the TT&C system that prevented sending the craft on its way.

  2. Just as a guess, since the mission was designed for long-term operation in orbit around Mars, I would think the basic thermal equilibrium of the satellite should keep the fuel liquid there when all the systems are working, and thus here (where there’s about twice as much solar energy) even if it’s not functioning.

  3. Not necessarily. The thermal equlibrium is based on the internal systems being on and functioning, thus generating heat that helps keep things at the right temperature. If the systems aren’t on, then the heat needed to prevent propellant from freezing comes from the batteries until they’re dead. If Phobos/Grunt is maintaining a stable attitude in Earth orbit, it means the attitude control system is still functioning. If that’s the case, it may be getting enough energy from the sun to keep the batteries at least partially charged. If it’s tumbling, the probe is dead. I doubt that the radiant heat from the sun would be enough to keep things thawed. Insulation works both ways.

    1. I’m not sure about that. The Phobos Grunt’s solar panels provide only 150 Watts for the internal systems, and the fuel tanks are arranged around the bottom end where they’re not close to the other systems. Normally they would even be shaded by the solar panels. But they are painted white, so maybe they would drop below the UDMH freezing point.

  4. Surely the Russians have an antisatellite, er, missile defense weapon with fortuitous excess capability against LEO targets. This sounds like a perfect opportunity for a demonstration of capability, er, operational test, er, public service hazard-mitigation exercise. Come on, all the cool kids are doing it…

  6. Well, we don’t actually know that the tanks are aluminum. The Russians say there are, but we have nothing to indicate it’s true.

    How well does aluminum stand up to nitrogen tetroxide and UDMH? I do know that nitrogen tetroxide is corrosive to aluminum. Also, the modified Fregat upper stage that’s the “bus” for Phobos-grunt was supposed to operate for years, including for the MOI burn. I can’t see a reason to rule out titanium tanks. (though I can see a motive for the Russians to claim that’s what’s up there).

    Could the fuel have frozen by now? I can’t see any reason to exclude the possibility, which would make even aluminum tanks a risk. That’s a LOT of highly toxic fuel (13 tons or so).

    It’s coming down fast now… 104 miles x 129 for the orbit as of today, and the rate of decay is ramping up fast. Just a few more days…

    1. Titan II was an all-aluminum rocket filled with N2O4 and Aerozine 50 (half hydrazine, half UDMH). If the N2O4 is dry enough, it’s no problem even for decade long storage. Same for A-50. However, Gemini Titan IIs had a habit of developing pinhole leaks in the N2O4 tanks and delaying the launch. As the rocket sat fueled, the tiny N2O4 leaks would become HNO3 upon contact with the humid air, and the leaks would eventually become too large. The solution was to slap an aluminum patch on, using sodium silicate as the bonding agent.

      1. Thanks for the info. I didn’t know that it was due to impure N204.

        Hrmm, I wonder how pure Russian N204 is? And how hard it is to keep that stuff anhydrous during transport and fueling?

    2. Oh, and it’s possible that the N2O4 is frozen (-11.2 C), but less likely that the UDMH is entirely so (-57 C). That quantity will eventually freeze if shaded, but I would expect it to take quite a while.

  7. Looks like the Russians are trying to blame sabotage by the West as a reason for the failure.

    http://rt.com/news/phobos-grunt-probe-failure-versions-445/

    Shady side of Earth: Western trace in space probe’s failure?
    Published: 10 January, 2012, 14:49
    Edited: 10 January, 2012, 20:20

    [[[Doomed Martian probe Phobos-Grunt, which was due to fulfill a Russian mission on one of the Red Planet’s moons, might have been a target of external influence. The probe failed while flying over the western hemisphere, outside of Russia’s control.]]]

    1. They do hint at Alaska, meaning HAARP, but don’t bother to say that it never passed over, or even was over the horizon of, any part of Alaska before the failure.

      Cunning of them to say “western Hemisphere” when they mean South America.

      Most of their failed mars probes have failed in the neighborhood of Mars, as I recall. I suppose they’ll blame a US base on Mars for this next?

      If this is their idea of believable propaganda, no wonder their Mars probes fail. 🙂

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