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Space Science

Putting the Odyssey Spacecraft in Martian Orbit 11

Posted by timothy from the go-fast-turn-left dept.
FortKnox writes: "There is an interesting article about NASA attempting to place the Odyssey Spacecraft in Martian Orbit on Oct 23rd. Looks like it is a tough maneuver. Maybe they should just say the trip to Mars was the mission, and putting it in orbit is a "bonus mission" like they did with Deep Space 1. Seems they do a better job if it isn't a criteria of the actual mission ;-)"
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Putting the Odyssey Spacecraft in Martian Orbit More

Putting the Odyssey Spacecraft in Martian Orbit

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  • That's like in Spaceballs! (Score:1, Funny)

    by Anonymous Coward
    Instead of the Winnebago, it's a Honda Odyssey! That's cool!

  • Doesn't sound easy... (Score:2, Interesting)

    by ndrw ( 205863 )
    Geez, I'd hate to be one of the guys in the control room on this one. With a) variably dense atmosphere, and b) major guesswork on how the heat will affect the spacecraft, I wouldn't be all that surprised if c) the ship failed! Also, can you imagine how difficult it is to "think ahead" and predict what's going on when the data you're looking at has taken a few minutes to get here from Mars? I guess that's why people consider rocket science difficult.

    I didn't see any real mention of the martian winds in this article, don't they get up to hundreds of miles per hour in the upper atmosphere? Couldn't that seriously screw up an aerobraking attempt? Or is that just a drop in the bucket compared to the speed of the spacecraft (which I didn't see in the article, but can probably be found on NASA's site - too bad I'm lazy)?

    This definitely gives pause when considering the difficulty of landing manned craft on the surface. With so many variables, you're almost guaranteed that something is going to go wrong. I'd hazard a guess that contingency planning is high on NASA's list right now!

    Insert funny tagline here.

    • plus the fact that aerobraking doesn't extend into a significant part of the atmosphere, where wind would even play a role. it will take place at the very top of the martian atmosphere (that's why it takes up to 100 passes) where there is not much wind if at all. the fierce martian winds spoken of are much closer to the planet's surface than the craft will ever go.
    • Geez, I'd hate to be one of the guys in the control room on this one. With a) variably dense atmosphere, and b) major guesswork on how the heat will affect the spacecraft, I wouldn't be all that surprised if c) the ship failed!

      Actually, you have a very good idea of how the heat will affect the craft, because you've already tested any spacecraft over its entire rated temperature range here on Earth before sending it into space (if you have any sense, at least).

      They know how much heating plowing through a given amount of atmosphere will provide. They just keep this low enough per pass that it doesn't take craft temperature outside its known-good range (with a healthy safety margin).

      Similarly, dealing with a factor of two uncertainty in the amount of atmosphere you'll be blowing through is straightforward too - assume the wost-case, and plot your course to keep the craft within spec. If you were wrong, no harm is done; you just need a few more orbits before you've lost the amount of speed you need to.

      The main impact, if I understand correctly, is on mission scheduling. Mission control *likes* to know within a millimetre or two where your craft will be the Tuesday after next, so that it can plan experiments for the Thursday following *that*. Extra uncertainty means a longer waiting period before you know you'll have settled into a circular orbit, cleaned up any irregularities, and be ready to start scientific measurements. This costs money and leaves the primary mission scientists biting their nails a bit longer.

      I didn't see any real mention of the martian winds in this article, don't they get up to hundreds of miles per hour in the upper atmosphere?

      Even at its slowest, the craft will be travelling at many thousands of miles per hour. If there's wind at all in the far reaches of the atmosphere where it will be braking, it won't make that big a difference compared to uncertainty about the thickness of the atmosphere at that height.

      This definitely gives pause when considering the difficulty of landing manned craft on the surface. With so many variables, you're almost guaranteed that something is going to go wrong.

      The good news is that, for aerobraking at least, nothing can go wrong that can't be compensated for over the next few orbits.

      Landings are a lot trickier, because you need a much greater change in velocity in a far, far shorter time, and if you screw up, you lose the craft. All they're doing for this craft is moving it from one orbit to another by slowly bleeding off velocity, which is much easier.
  • Although the winds on Mars are formidable, the atmosphere, especially at altitude, is much thinner than Earth's as Mars' mass is several times less than Earth's and thus it gravitational field is weaker, and unable to hold as much atmospheric gases as say the Earth or Jupiter, etc.
    Therefore, even if the wind blows horribly, it is not as much of a problem as the mass/density of the Martian atmosphere is less; the winds push is less severe.
    • Also the 'scale height' on Mars is larger than it is on earth (by a factor of two i belive). The 'scale factor' is the altitude increase you have to do in order to lower the atmospheric pressure to half as what it was. On earth, this is arround 8 km i think. and on mars it is somewhat larger.

      The implication of this, is that you have a larger 'window' to hit where tha density of the atmosphere is as you want. Not to say that it makes it so much easier considering the time-lag in comunications, but at least it allows for larger uncertainty (I bet the folks at NASA can use all the benefits they can get..).


      Anyways. Cheers for the NASA for their continued effort to put humans into space where we belongs, for even speaking geologically, the earth isn't going to last, and even the sun dies eventually. so if we can awoid blowing each other up, we will have to go to the stars eventually, why not start by going to Mars??


      Yours Yazeran.


      Plan: To go to Mars one day with a hammer.

  • Considering all of the miserable failures that have occurred so far in past Mars missions I am hoping that the meters/inches thing doesn't rear its ugly head again... that was just plain embarrasing.

    Someone should start a deathpool for this one. Time/date of failure and then a seperate pool for what will be the lame excuse.

    I hate to sound so negative but the rate of success on these missions is really frustrating. The missions went so much better when they were planned redundancies in the entire project like Viking 1 & 2. The cost of building two shouldn't double the cost of the entire project. In R&D the cost of two is usually 1.5-1.7 times the cost of building just one.

    Hopefully this goes well and I can cheer up about it but until then I am not getting my hopes up on this one.


  • Maybe they should just say the trip to Mars was the mission, and putting it in orbit is a "bonus mission"



    No, you don't get it. Odyssey was a Mars mission.

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