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Mars rover says: 'good evening gale crater!'

Discussion in 'Science & Technology' started by micropage7, Aug 7, 2012.

  1. W1zzard

    W1zzard Administrator Staff Member

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    just to clarify, the power source is not a nuclear reactor in the sense of a commercial power plant.

    curiosity uses the heat from (quickly decaying) radioactive stuff to generate electricity using thermocouples. there are no moving parts, no cooling loop, no material is consumed or exhaust.

    it produces just 125 W
  2. TheMailMan78

    TheMailMan78 Big Member

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    The flux capacitor powers the turbo nabulator Tesla engine to be precise.


    Anyway......I'm assuming Uranium or is that to slow a decay? I have read ZERO on this.
  3. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    It uses plutonium-238 which has a half-life of 87.7 years. It loses 0.787% power output every year.

    If your 125w figure is correct, everything I see says it will produce about 100w in 14 years. 100w is the minimum required to operate, apparently.
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  4. Drone

    Drone

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    Gotta wait ...
  5. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    Yeah, because of the distance, they have to use low-bandwidth tranmission signals. It will take a long time for them to send and they can probably only do that when it isn't sending information needed to operate it.

    Black and white pictures take 1/3rd the bandwidth to transmit.
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  6. mlee49

    mlee49

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    Will the XBand comm transmit the Hi-RES shots or will it relay off the orbiting ones like the current pictures?

    Just ripped this about the main camera(1 of 17 btw):

  7. TheMailMan78

    TheMailMan78 Big Member

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    Plutonium? Really? No cooling?
  8. mlee49

    mlee49

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    It is -200 to +86F over there, read the wiki homeboy
  9. TheMailMan78

    TheMailMan78 Big Member

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    86F ambient temp for Plutonium is high. If it was -200 consistently ok. But its not. The amount of Plutonium in that thing must be the size of a green pea. :laugh:

    Maybe its partly depleted?
  10. gopal

    gopal

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    I know it is immposible to get color pic of Mars from mars but B/W is not cool and i cannot see anything clear.
  11. NdMk2o1o

    NdMk2o1o

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    155 billion huh? :roll:
  12. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    It has 32 pellets about the size of a marshmellow each. It operates on the heat produces by radioactive decay, not by a nuclear chain reaction like nuclear power plants do.


    It has color cameras but it will take a long time for the photos to be sent.
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  13. TheMailMan78

    TheMailMan78 Big Member

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    lol yeah I know. But "hot" plutonium produces a lot of heat. These things have to be slightly deleted.
  14. gopal

    gopal

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    This thing is going to burn out MARS.:twitch:
  15. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    It likely has a cooling loop which redirects the heat to heatsinks on the rover if it is getting too hot. Even if it doesn't, they've accounted for it in the design of the rover (likely allowing it to hit peak temperature and sustain it).
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  16. TheMailMan78

    TheMailMan78 Big Member

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    Yes. Plutonium marshmallow's are going to burn out Mars.

    I would love to see that thing up close. Its days like this I wish I would have never dropped out of Aeronautical Engineering. By now I might have been involved in this thing. So cool.
  17. W1zzard

    W1zzard Administrator Staff Member

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    what are you talking about? hot is an arbitrary state of temperature, not a measure of energy or power. is your argument "a red hot piece of metal produces a lot of heat" ?

    do you mean "depleted" ? that's not the case. depleted means that the isotopes are stable or have extremely long lifetimes. in that case there would not be much heat for power generation.

    http://en.wikipedia.org/wiki/Radioisotope_Thermoelectric_Generator
    good read
    Last edited: Aug 7, 2012
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  18. FordGT90Concept

    FordGT90Concept "I go fast!1!11!1!"

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    Pu-238 can generate temps exceeding 1000C (1832F) on the surface depending on configuration. That's "hot" by pretty much any definition. XD
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  19. TheMailMan78

    TheMailMan78 Big Member

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    This is what I mean.

    Not hot in radioactivity. I mean hotter then a frying pan. :laugh: So yeah they would have to be depleted some or passive cooling wouldn't work in 85F without cooling. You said there is no cooling loop or working parts so whatever plutonium they have in there has to be depleted. That and all they are getting is 125 W. Its depleted or they put the most inefficient generator in space on it.

    Thats all I'm saying.

    Pu2o gets hot as hell. In space its no big deal. In 85F it can become and issue. There HAS to be something cooling it.
    Last edited: Aug 7, 2012
  20. W1zzard

    W1zzard Administrator Staff Member

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    i meant cooling loop in the context of a nuclear reactor (water, pumps, cooling towers)

    the heat output on the mars probe is 2000 W, from 4.8 kilograms of Pu-238. the thermocouples are super-inefficient, they generate around 100 W. some secondary heat is used to keep other subsystems warm during night/winter/space.

    [​IMG]
    the assembly has white fins on the outside to dissipate extra heat

    any heat source that can not remove enough heat will get infinitely hot
    Just like every 2000W heater, as long as you have 2000 W of cooling, its temperature will not increase. if you remove more than 2000W it will cool down, if you remove less it will heat up.

    actually i'm not sure if it's easier to cool in space or on mars. in space you can only radiate it away. on mars you have cooling effects from the (thin) atmosphere, but you lose some radiative cooling potential because you have the ground at higher temperature than space
    Last edited: Aug 7, 2012
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  21. digibucc

    digibucc

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    it's all bureaucracy, it's easier to get money earmarked for a project with a short specific lifespan and defined goals. BUT, IF, within that project they can find ways to make it more effective, last longer, and generally be cooler - they take it. however the initial mission stays the same, because that's what was agreed upon and what they are paid for.

    look at it like this, after 2 years mission accomplished. anything we learn after that is just gravy :)
  22. Norton

    Norton WCG-TPU Team Captain

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    RTG info

    Excellent read :toast:

    IIRC the Plutonium fuel source used for the RTG on this rover was the backup/spare unit for the Cassini probe.... just can't remember where I read it atm....*See Edit*

    *EDIT- The spare RTG from Cassini was used for the New Horizons probe that's on its way to Pluto..... I knew it went somewhere :eek:
    Link:
    http://en.wikipedia.org/wiki/Cassini-Huygens#Plutonium_power_source
    Last edited: Aug 7, 2012
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  23. TheMailMan78

    TheMailMan78 Big Member

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    I agree cooling in space has its advantages as well as disadvantages. If Mars was sub zero all the time then with the thin atmosphere it would cool better then space AFAIK. Problem is when it goes above 20F is when a "passive" cooling system becomes an issue. This is why we only have a few of these kinda (very similar) generators in Alaska........north Alaska and I believe they have a reserve cooling system for emergency's but don't quote me on that. No matter what its an engineering feat to keep that cool and working on an alien planet. Space is one thing. The temperature is "fixed" for the most part. The variables of a planet is a WHOLE different story. Very cool tech.
  24. Norton

    Norton WCG-TPU Team Captain

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    The rovers RTG was active in our atmosphere and didn't overheat. It did run hot enough that it needed to have a large safety cage around it.

    See pic/caption:
    http://en.wikipedia.org/wiki/File:MMRTG_for_the_MSL.jpg

    On Mars it's not an issue... no reason to protect it from people and the cooling system would run better on Mars than Earth.

    It will be fine as long as no Martians burn their tentacles on it- then there will be an inter-planetary lawsuit for Judge Judy to preside over :D
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  25. Drone

    Drone

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    Here's a couple of images from Curiosity. NASA released them today

    [​IMG]
    [​IMG]
    Last edited: Aug 8, 2012
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