Michael Meyer, about Phoenix and MSL |
Michael Meyer, about Phoenix and MSL |
Sep 25 2006, 10:01 AM
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#1
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Member Group: Members Posts: 153 Joined: 11-December 04 Member No.: 120 |
http://www.marsdaily.com/reports/Managing_...ssions_999.html
Michael Meyer, lead scientist for NASA's Mars Exploration Program, spoke at the recent Viking anniversary celebration. One remarkable quote: "Considering how long the Spirit and Opportunity rovers have lasted beyond their design lifetimes, it almost boggles the mind to think how long MSL could last. It may be there to greet the astronauts when they arrive on Mars." That's what I call optimism. I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version? |
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Sep 25 2006, 10:02 AM
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Founder Group: Chairman Posts: 14434 Joined: 8-February 04 Member No.: 1 |
Or the sort of failures we're seing on MER - actuators, motors etc.
Doug |
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Sep 25 2006, 11:07 AM
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#3
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Senior Member Group: Members Posts: 2922 Joined: 14-February 06 From: Very close to the Pyrénées Mountains (France) Member No.: 682 |
Do we know for sure whether MSL will be solar or RTG's?
OR When will we know? Did they past the critical desgin yet? -------------------- |
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Sep 25 2006, 02:12 PM
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Member Group: Members Posts: 153 Joined: 11-December 04 Member No.: 120 |
Apparently not.
According to Meyer the project is still in a 'conceptual' phase. That sounds a bit scary, doesn't it? |
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Sep 25 2006, 04:47 PM
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#5
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Member Group: Members Posts: 321 Joined: 6-April 06 From: Cape Canaveral Member No.: 734 |
MSL has its PDR in June. MSL DEIS briefings are this week.
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Sep 25 2006, 05:38 PM
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#6
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Senior Member Group: Members Posts: 2922 Joined: 14-February 06 From: Very close to the Pyrénées Mountains (France) Member No.: 682 |
MSL has its PDR in June. MSL DEIS briefings are this week. Those accronyms again! I've just got "june" and "week" Well, MSL too, but can you help with this Jim ? BTW, I understand this week is important. -------------------- |
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Guest_AlexBlackwell_* |
Sep 25 2006, 05:43 PM
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#7
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Guests |
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Guest_Analyst_* |
Sep 25 2006, 06:55 PM
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Guests |
I always thought that the lifespan of an RTG was pretty predictable and that in case of MSL it lasted for about 2 earth years. Maybe he's talking about the solar array powered version? The funny thing about RTGs is there predictable power reduction. They don't die instantly like an empty battery (after i.e. two years). The output decreases very gracefully. The Voyager RTGs are generating today more than half of their output at launch in 1977. So if MSL uses a RTG (I can't imagine it using solar panels and I can't imagine this decision hasn't been taken already.) and if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years. A lot of if's. But also a beancounters nightmare. Imagine the 15th mission extension. Analyst |
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Sep 25 2006, 08:25 PM
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#9
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
... if it behaves like the Voyager RTGs and if all the other rover subsystems keep working and if the rover can work with 50 percent power (like MER) it can still be arround after 30 years. That might be the case for the RTG's itself but I'm certain that the RTG will be used to charge up a battery sub-system that will act as a buffer for power demands of the rover's main sub systems. It's less likely that the battery\power mangement sub system will be good for 30 years. On the issue of solar vs RTG - I assume that this is being kept vague simply to avoid attracting the ire of the anti nuke crowd. I can't see how a solar panel solution would be sufficient given the power requirements and mission duration. The MER's survival for 2+ years through good luck does not change the fact that MSL's power requirements would require _huge_ panels (>8m^2) in order to ensure that it could survive the full blown Martian dust storms that it's mission duration absolutely requires that it needs to be able to survive. |
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Sep 26 2006, 01:31 AM
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#10
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Member Group: Members Posts: 307 Joined: 16-March 05 Member No.: 198 |
The MER's survival for 2+ years through good luck does not change the fact that MSL's power requirements would require _huge_ panels (>8m^2) in order to ensure that it could survive the full blown Martian dust storms that it's mission duration absolutely requires that it needs to be able to survive. Using solar panels would also presumably limit the MSL to equatoral regions like the MERs (or else increase the panel acreage required even more). ====== Stephen |
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Sep 26 2006, 04:06 AM
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Senior Member Group: Members Posts: 1281 Joined: 18-December 04 From: San Diego, CA Member No.: 124 |
Maybe they are planning to use the ChemCam to zap the solar panels clean? I kid!
I can't see how this mission could be solar powered and still be the MSL we have come to expect in 2009. I would also imagine that all things being equal electro-mechanically, a RTG mission lifetime would be very predictable, with none of the power budget uncertainty the MERs face. -------------------- Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test |
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Sep 26 2006, 09:40 AM
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#12
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Senior Member Group: Members Posts: 1870 Joined: 20-February 05 Member No.: 174 |
I do not know the possible engineering constraints on "supplementary" solar cells, but if the weight of a square meter or two on advantageously oriented surfaces on top of the rover wasn't a big problem, it seems that they might be useful as a supplementary power source. There's additional power handling hardware and cabling and the like, but it might be worth it.
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Sep 26 2006, 11:39 AM
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#13
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Member Group: Members Posts: 477 Joined: 2-March 05 Member No.: 180 |
That might be the case for the RTG's itself but I'm certain that the RTG will be used to charge up a battery sub-system that will act as a buffer for power demands of the rover's main sub systems. It's less likely that the battery\power mangement sub system will be good for 30 years. They managed to squeeze more than 15 years out of Hubble's batteries, and they get recharged about every 90 minutes, if memory serves. |
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Sep 26 2006, 04:23 PM
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Dublin Correspondent Group: Admin Posts: 1799 Joined: 28-March 05 From: Celbridge, Ireland Member No.: 220 |
They managed to squeeze more than 15 years out of Hubble's batteries, and they get recharged about every 90 minutes, if memory serves. Those are very different beasties. Hubble uses pressurised Nickel Hydrogen batteries. Those have excellent life time and recharge cycle characteristics but are relatively inefficient from a power storage\density POV. The MER's use Lithium Ion\Lithium Polymer batteries and MSL almost certainly will too. |
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Dec 23 2006, 07:30 AM
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Newbie Group: Members Posts: 4 Joined: 20-December 06 Member No.: 1498 |
MSL is an RTG powered rover.
Keep in mind there are two other benefits from RTG's. 1. Lots of waste heat which can be used to heat the rover. This is a significant power savings. 2. No batteries.. = mass savings ;) |
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