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Michael Meyer, about Phoenix and MSL
djellison
post Dec 23 2006, 09:43 AM
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MSL will still have a battery, as all other RTG powered spacecraft have - to allow for peak power useage over and above the RTG output.

Doug
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Jim from NSF.com
post Dec 23 2006, 01:51 PM
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QUOTE (djellison @ Dec 23 2006, 04:43 AM) *
MSL will still have a battery, as all other RTG powered spacecraft have - to allow for peak power useage over and above the RTG output.

Doug


Actually, MSL will be powered by the battery and the RTG will be used to charge it. Mission ops will be much like MER where there will be periods of "inactivity" to allow the battery to recharge.
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Guest_Analyst_*
post Dec 23 2006, 02:54 PM
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QUOTE (djellison @ Dec 23 2006, 10:43 AM) *
MSL will still have a battery, as all other RTG powered spacecraft have - to allow for peak power useage over and above the RTG output.


Voyager did not have a battery, I am pretty sure Pioneer 10/11 didn't have one too. Not sure about Galileo and Ulysses, but I guess both didn't have one eighter. Cassini has one to power the radar. New Horizons doesn't have one. I believe the ALSEPs did not have a battery too.

It's pretty uncommon for RTG spacecraft to have a battery.

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helvick
post Dec 23 2006, 05:10 PM
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QUOTE (Analyst @ Dec 23 2006, 02:54 PM) *
It's pretty uncommon for RTG spacecraft to have a battery.

That is probably true but a power subsystem that enables power acumulation enables much higher peak power loads than the peak power output from your RTG and that is a very good thing for a rover even if it is not hugely important for orbiter\flyby space craft.

It wouldn't be a very effective use of the resources when you have 2400 whr of power per sol but you keep yourself limited by a 100watt peak load.
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tedstryk
post Dec 23 2006, 05:23 PM
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QUOTE (Analyst @ Dec 23 2006, 02:54 PM) *
Voyager did not have a battery, I am pretty sure Pioneer 10/11 didn't have one too. Not sure about Galileo and Ulysses, but I guess both didn't have one eighter. Cassini has one to power the radar. New Horizons doesn't have one. I believe the ALSEPs did not have a battery too.

It's pretty uncommon for RTG spacecraft to have a battery.

Analyst


Pioneers 10 and 11 did have a battery, though it was useless by the later part of the mission.


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Guest_Analyst_*
post Dec 24 2006, 09:32 AM
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QUOTE (helvick @ Dec 23 2006, 06:10 PM) *
That is probably true but a power subsystem that enables power acumulation enables much higher peak power loads [...]


I am well aware of the value of a battery, but to say "... as all other RTG powered spacecraft have" is clearly wrong.

Analyst
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djellison
post Dec 24 2006, 10:52 AM
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I thought they did....MSL certainly will, and I know others have, I assumed they all had - my bad.

DOug
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Bob Shaw
post Dec 24 2006, 11:06 PM
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Strangely, Sojourner's battery was a primary - ie non-rechargeable - battery - the solar panel didn't recharge it; and many allegedly 'non-nuclear' spacecraft have employed 'heaters' which use radioactive decay to heat the vehicle. Funny old world, eh?

Bob Shaw


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DFinfrock
post Dec 27 2006, 12:57 AM
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Off topic...

But when we get around to sending a lander/rover into Shackleton Crater at the lunar south pole, will there likely be only a battery to power it, for a short-term mission? I can't imagine sending an RTG there if there is a hope to use any possible ice resources that may exist. And a solar panel wouldn't be of much use in a perpetually shadowed crater.

David
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Bob Shaw
post Dec 27 2006, 08:52 AM
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QUOTE (DFinfrock @ Dec 27 2006, 12:57 AM) *
Off topic...

But when we get around to sending a lander/rover into Shackleton Crater at the lunar south pole, will there likely be only a battery to power it, for a short-term mission? I can't imagine sending an RTG there if there is a hope to use any possible ice resources that may exist. And a solar panel wouldn't be of much use in a perpetually shadowed crater.

David



David:

An RTG would be ideal - simple, light, happy in the cold and darkness! And although you might not want to hug one on a long-term basis, pretty safe. One problem with RTGs is their rarity - fuel and hardware production is erratic, to put it mildly.

Alternatives *might* include a long power cable leading to a sunlit lander, or even an internal combustion engine (the exhaust would be fun!). Still, there *have* been stranger propulsion systems suggested over the yeras, such as the mobile windmill on Venus (I kid you not)...

Bob Shaw


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Guest_Geographer_*
post Jun 21 2007, 10:00 AM
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Of all the things to protest in the world, tiny nuclear reactors on one-way trips into space for the pursuit of science is awfully trivial. I don't understand why procuring RTGs is a problem: shouldn't NASA with its government connections get top priority?
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Jim from NSF.com
post Jun 22 2007, 11:31 AM
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QUOTE (Geographer @ Jun 21 2007, 06:00 AM) *
Of all the things to protest in the world, tiny nuclear reactors on one-way trips into space for the pursuit of science is awfully trivial. I don't understand why procuring RTGs is a problem: shouldn't NASA with its government connections get top priority?

Government connections? NASA is the government and that why RTG procurement is hard. The "people" want a rigorous (maybe overly) process to make sure the environment and people are not endangered.

As for "top priority", there are other goverment users
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edstrick
post Jun 23 2007, 04:47 AM
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There's also the one minor detail.. Nukes are *** EVIL ***. Only practitioners of the dark side of the force dabble with nukes... (etc. etc. etc.. froth, rage, babble....)

I was VASTLY relieved that there has been a declining trend of anti-nuke hobbyists entertaining themselves at the Cape from Galileo to Cassini to New Horizons... may that trend continue!
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mchan
post Jun 23 2007, 08:16 AM
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QUOTE (Jim from NSF.com @ Jun 22 2007, 04:31 AM) *
Government connections? NASA is the government and that why RTG procurement is hard. The "people" want a rigorous (maybe overly) process to make sure the environment and people are not endangered.

As for "top priority", there are other goverment users

Interesting last comment. There were press stories that mentioned the use of RTG's by remote information collection equipment emplaced on the ocean floor and in the Himalayas. But that was during the Cold War.

QUOTE (edstrick @ Jun 22 2007, 09:47 PM) *
I was VASTLY relieved that there has been a declining trend of anti-nuke hobbyists entertaining themselves at the Cape from Galileo to Cassini to New Horizons... may that trend continue!

One can count on the hardcore anti-nuke folks to be at the MSL launch.
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lyford
post Jun 23 2007, 04:51 PM
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QUOTE (mchan @ Jun 23 2007, 01:16 AM) *
One can count on the hardcore anti-nuke folks to be at the MSL launch.

So they will then be standing in the "radioactive fallout zone" if there is a launch vehicle failure? biggrin.gif

Seriously, if one is going to spend one's time protesting nuclear material on top of a rocket, one would probably want to spend some time worrying about these ones, instead of a wee lil' RTG....

EDS - feel free to cull if too political for the board.


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