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MSL's Power Source
Guest_exobioquest_*
post Nov 27 2005, 04:46 PM
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Hi, new here.

I'm wondering if any news has come down about finalizing what MSL will run on?

Will it be 2 Boeing's MMRTG (at ~100 watts?) or Lockheed Martin’s SRG (again ~100watts?), have they decided yet? Willl MSL use the RPS to trickle charge a battery or will MSL run on the RPS only? God I hope solar is not a option is anyone pushing for it?
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mike
post Nov 29 2005, 04:04 PM
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Gasoline production is a front so the military can fuel their killing machines.
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Guest_exobioquest_*
post Nov 29 2005, 06:49 PM
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mcaplinger,

Its unlikely the mass of the SRG will be more then the MMRTG, the mass estimates are ranged now so it is possible the MMRTG will weigh less, but so far SRG usually has a range average a few kg below the MMRTG.

Also your not considering all the extra weight of the radiators needed for the cruise staged to keep the MMRTG cool.

Pu238 last cost ~$1400 per gram, so for the purchasing of the fuel alone (not counting the making of the GPHS) the MMRTG's fuel will cost 5.6 million while the SRG's will cost 1.4 million. Can anyone find out how much a GPHS cost to make? So just fuel cost the SRG is 4.2 million cheaper, not much but when the mission goes over budget every dollar less overbudget it goes the less likely the mission will get bumped up.

mchan,

those nuts and their logic its scares me so, how likely you think they will make a effective stink?
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mcaplinger
post Nov 29 2005, 07:15 PM
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QUOTE (exobioquest @ Nov 29 2005, 10:49 AM)
Its unlikely the mass of the SRG will be more then the MMRTG, the mass estimates are ranged now so it is possible the MMRTG will weigh less, but so far SRG usually has a range average a few kg below the MMRTG.

Also your not considering all the extra weight of the radiators needed for the cruise staged to keep the MMRTG cool.

*


You make a fair point about the radiators, though even MPF and MER had radiator systems.

I can't assess the mass estimates of the RTG systems themselves without detailed technical descriptions.

However, from http://solarsystem.nasa.gov/scitech/display.cfm?ST_ID=705

"Initially, the MMRTG could have an advantage from a mass perspective, as current NASA/DOE guidelines recommend that early missions using SRGs carry at least one redundant SRG unit until its reliability has been verified [11]. This means that early missions using SRGs would need to carry a minimum of two SRG units. Thus, for early missions (where a redundant SRG would be required), the MMRTG (at <45 kg [10]) would be the lighter option for spacecraft requiring one or two RPS units."

And according to the NASA FY06 budget request ( http://www.nasa.gov/pdf/107489main_FY06_1_sae.pdf ), page 2-22 "MSL - Department of Energy for Multi Mission Radioisotope Thermoelectric Generators" and page 2-14 "Radioisotope Power System (RPS): Deleted Small RPS or second generation Sterling (SRG), and RPS Power Conversion Technology (RPCT)." I think it's clear from that that MSL is planning to use the MMRTG.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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Guest_exobioquest_*
post Nov 29 2005, 07:38 PM
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mcaplinger,

The SRG has 2 55w sterling engines so when they say an extra do that mean 3 55w engines? That could not allow for easy counter piston action and cause much vibration. Maybe they mean 2 SRGs total, which would be 200w of power! That would be Fing wonderful from a mission perspective, all that extra power! That would still be 1/2 the fuel and 1/2 the heat output of the MMRTG, but the weight on the rover its self would definitely be an extra 25-40kg.

I think they were talking about the second generation SRG: the ~350 watt version that was under development or something.
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mcaplinger
post Nov 29 2005, 08:24 PM
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QUOTE (exobioquest @ Nov 29 2005, 11:38 AM)
Maybe they mean 2 SRGs total, which would be 200w of power!
*


The full document makes it pretty clear that yes, they mean two entire separate SRGs if you need the power from one.

If you were an advocate of the SRG you might say that was an unfair imposition, but them's the rules at the moment.


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helvick
post Nov 29 2005, 08:41 PM
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QUOTE (mcaplinger @ Nov 29 2005, 09:24 PM)
If you were an advocate of the SRG you might say that was an unfair imposition, but them's the rules at the moment.
*

Well if I was paying hundreds of millions for a mission then I'd say that them would be reasonable rules, much as I like the SRG concept it needs to be flight proven before it's used for something as important as this.
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Guest_exobioquest_*
post Nov 29 2005, 08:57 PM
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I would be estactic if anything that can provide 200w (4800wh) of continues power was going on the MSL, be it a MMRTG or SRG. With 2 SRG weight is the only major problem, you still have less thermal and fuel needs then the MMRTG. weight over the whole spaceship could be negated with the reduction to the thermal control system and also is the cruise stage going to need solar panals?, maybe at 100w but most likely not with 200w, that some possible weight savings. At 200w (and considering the SRGs lasts a long as claimed) MSL would most likely last for a decade or more! At 200w (and not adding lighting for night time driving) MSL could do over a km a day of driving! It could do hundreds of km over its mission! Just the idea makes me drool!
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mcaplinger
post Nov 29 2005, 10:00 PM
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QUOTE (exobioquest @ Nov 29 2005, 12:57 PM)
At 200w (and considering the SRGs lasts a long as claimed) MSL would most likely last for a decade or more! At 200w (and not adding lighting for night time driving) MSL could do over a km a day of driving! It could do hundreds of km over its mission! Just the idea makes me drool!
*


Even if any of these things were true (they're not, as far as I know -- there's nothing terribly enabling about going to twice the RTG power. You still need batteries, you still don't have enough power for active thermal control of all elements so you have thermal cycling wearout, you still have mechanical wearout problems, and there is no way that MSL is ever going to drive 1 km/day under any circumstances no matter how much power it has) MSL is using the MMRTG anyway. So your drool is wasted. smile.gif


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helvick
post Nov 29 2005, 10:30 PM
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QUOTE (mcaplinger @ Nov 29 2005, 11:00 PM)
and there is no way that MSL is ever going to drive 1 km/day under any circumstances no matter how much power it has)  MSL is using the MMRTG anyway.
*

That's an important point. Raw speed isn't of much use, the objective is to try to find things and that requires that MSL looks very closely at the stuff around it, not just race along for the sake of it. There might be the odd dash or two that are marginally faster than the flat out rates we've seen from Opportunity and Spirit but I suspect it will spend a lot of time making about the same rate of progress that the MER's do. And there's nothing wrong with that.
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Guest_exobioquest_*
post Nov 29 2005, 10:49 PM
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helvick,

Sure there is nothing wrong wit MER speeds, but MSL will have:

-10X the upload speed with MRO in orbit, Even without MTO, MRO is going to provide major communication bandwidth improvements.

-A much faster processor (RAD750?) so autonav would be faster and/or more advance, might be able to command MSL to go up to a rock sample it and then go up to another sample it and so forth by sending only one set of commands and the rover does all the rest autonomously.

-Onboard sample loader: if all the instruments (except the microcam) run of samples provided by the arm to a sample loader in the rovers body, then MSL could get a sample from one rock and move on to another while its analyzing the sample it drilled up: so MSL could sample several rocks in the time it takes MER to do one!

edit: spelling/grammer
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Posts in this topic
- exobioquest   MSL's Power Source   Nov 27 2005, 04:46 PM
- - helvick   QUOTE (exobioquest @ Nov 27 2005, 05:46 PM)Go...   Nov 27 2005, 06:30 PM
|- - exobioquest   QUOTE (helvick @ Nov 27 2005, 12:30 PM)The ME...   Nov 27 2005, 06:53 PM
|- - helvick   QUOTE (exobioquest @ Nov 27 2005, 07:53 PM)Th...   Nov 27 2005, 08:05 PM
|- - exobioquest   Well maybe your right about anti-nuclear nuts, I h...   Nov 27 2005, 08:38 PM
|- - helvick   QUOTE (exobioquest @ Nov 27 2005, 09:38 PM)35...   Nov 27 2005, 09:45 PM
||- - exobioquest   From what I have read SRG has survived several yea...   Nov 27 2005, 10:18 PM
|- - mchan   QUOTE (exobioquest @ Nov 27 2005, 12:38 PM)We...   Nov 29 2005, 05:46 AM
- - DEChengst   I'm quite sure MSL would survive after the bat...   Nov 27 2005, 09:14 PM
|- - exobioquest   Ya, but I don't think 100watts is enough to do...   Nov 27 2005, 09:30 PM
- - mcaplinger   QUOTE (exobioquest @ Nov 27 2005, 08:46 AM)Wi...   Nov 28 2005, 03:59 PM
|- - exobioquest   QUOTE (mcaplinger @ Nov 28 2005, 09:59 AM)Acc...   Nov 28 2005, 04:57 PM
|- - mcaplinger   QUOTE (exobioquest @ Nov 28 2005, 08:57 AM)We...   Nov 28 2005, 05:30 PM
|- - mcaplinger   QUOTE (mcaplinger @ Nov 28 2005, 09:30 AM)How...   Nov 29 2005, 05:22 AM
- - BruceMoomaw   Apparently the Stirling version simply won't b...   Nov 29 2005, 01:18 AM
|- - exobioquest   QUOTE (BruceMoomaw @ Nov 28 2005, 07:18 PM)Ap...   Nov 29 2005, 03:35 AM
- - mike   Gasoline production is a front so the military can...   Nov 29 2005, 04:04 PM
|- - exobioquest   mcaplinger, Its unlikely the mass of the SRG will...   Nov 29 2005, 06:49 PM
|- - mcaplinger   QUOTE (exobioquest @ Nov 29 2005, 10:49 AM)It...   Nov 29 2005, 07:15 PM
||- - exobioquest   mcaplinger, The SRG has 2 55w sterling engines so...   Nov 29 2005, 07:38 PM
||- - mcaplinger   QUOTE (exobioquest @ Nov 29 2005, 11:38 AM)Ma...   Nov 29 2005, 08:24 PM
||- - helvick   QUOTE (mcaplinger @ Nov 29 2005, 09:24 PM)If ...   Nov 29 2005, 08:41 PM
||- - exobioquest   I would be estactic if anything that can provide 2...   Nov 29 2005, 08:57 PM
||- - mcaplinger   QUOTE (exobioquest @ Nov 29 2005, 12:57 PM)At...   Nov 29 2005, 10:00 PM
||- - exobioquest   QUOTE (mcaplinger @ Nov 29 2005, 04:00 PM)Eve...   Nov 29 2005, 10:26 PM
|||- - mcaplinger   QUOTE (exobioquest @ Nov 29 2005, 02:26 PM)An...   Nov 30 2005, 12:34 AM
|||- - Marslauncher   QUOTE (mcaplinger @ Nov 30 2005, 12:34 AM)See...   Nov 30 2005, 12:47 AM
||- - helvick   QUOTE (mcaplinger @ Nov 29 2005, 11:00 PM)and...   Nov 29 2005, 10:30 PM
||- - exobioquest   helvick, Sure there is nothing wrong wit MER spee...   Nov 29 2005, 10:49 PM
||- - helvick   QUOTE (exobioquest @ Nov 29 2005, 11:49 PM)Su...   Nov 29 2005, 11:10 PM
||- - RNeuhaus   QUOTE (helvick @ Nov 29 2005, 06:10 PM)I...   Nov 30 2005, 03:34 AM
||- - exobioquest   What is this: "NASA is considering nuclear en...   Jan 15 2006, 04:57 AM
||- - mcaplinger   QUOTE (exobioquest @ Jan 14 2006, 08:57 PM)So...   Jan 15 2006, 06:12 AM
||- - helvick   QUOTE (mcaplinger @ Jan 15 2006, 07:12 AM)I h...   Jan 15 2006, 09:35 AM
|||- - exobioquest   Well what is the max the MERs gets? what 900-1000w...   Jan 15 2006, 06:06 PM
|||- - helvick   QUOTE (exobioquest @ Jan 15 2006, 07:06 PM)We...   Jan 15 2006, 06:57 PM
|||- - RNeuhaus   QUOTE (helvick @ Jan 15 2006, 01:57 PM)For a ...   Jan 16 2006, 03:14 AM
|||- - helvick   QUOTE (RNeuhaus @ Jan 16 2006, 04:14 AM)Not s...   Jan 16 2006, 03:26 AM
||- - RNeuhaus   QUOTE (mcaplinger @ Jan 15 2006, 01:12 AM)I h...   Jan 16 2006, 03:04 AM
|- - mchan   QUOTE (exobioquest @ Nov 29 2005, 10:49 AM)th...   Nov 30 2005, 02:43 AM
|- - exobioquest   Well if the MMRTG is set I can only hope they can ...   Nov 30 2005, 02:48 AM
- - mike   Personally I don't think any anti-RTG-type pro...   Nov 29 2005, 08:09 PM
- - BruceMoomaw   It's about to be declared the officially, firm...   Nov 30 2005, 02:29 AM
- - djellison   Yes - it's clearly just being 'polite...   Jan 15 2006, 09:09 AM
- - Analyst   Mike Griffin said at the NH press conference MSL w...   Jan 18 2006, 10:06 AM
- - pospa   DoE's Idaho National Laboratory (MMRTG supplie...   Nov 23 2011, 12:20 PM
- - monty python   Thanks pospa. I learned a lot from that.   Nov 24 2011, 10:52 AM
- - jmknapp   I saw a presentation on YouTube where it was state...   Jul 12 2012, 08:05 PM
- - djellison   MSL has a battery, just like MER. Don't thin...   Jul 12 2012, 09:19 PM
|- - jmknapp   QUOTE (djellison @ Jul 12 2012, 04:19 PM)...   Jul 13 2012, 12:09 AM
|- - djellison   QUOTE (jmknapp @ Jul 12 2012, 05:09 PM) I...   Jul 13 2012, 07:22 AM
|- - jmknapp   QUOTE (djellison @ Jul 13 2012, 03:22 AM)...   Jul 13 2012, 02:43 PM
||- - mcaplinger   QUOTE (jmknapp @ Jul 13 2012, 07:43 AM) I...   Jul 13 2012, 04:12 PM
|- - RoverDriver   QUOTE (djellison @ Jul 13 2012, 12:22 AM)...   Jul 13 2012, 09:34 PM
- - nprev   What fluid is used in the loop, Mike? An ammonia s...   Jul 13 2012, 09:26 PM
|- - mcaplinger   QUOTE (nprev @ Jul 13 2012, 02:26 PM) Wha...   Jul 13 2012, 10:02 PM
- - nprev   Ah. Thanks!   Jul 13 2012, 10:44 PM
- - MarsEngineer   The cooling loop (heat rejection subsystem or HRS)...   Jul 14 2012, 06:06 PM


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