New MSL and MER comparison Image from JPL, Setting Expectations for Future Generations Options

[jabe]

ok..I took a screen capture of the jan 26th briefing..but not sure how to put in the picture lol
I got it from spaceflightnow clip..near middle of page..I'm sure there is a larger version somewhere


edit.: ok I'm an idiot...didn't look low enough lol

[ElkGroveDan]

Hmm, this makes me wonder - other than the MERs, is there any moving machinery with wiring looms and motors and complex joints that has been operated long term in an environment as hostile as Mars?
Chris

I used to drive a 74 Vega in and around the cold of Bozeman, Montana and then home through the Mojave desert to Los Angeles every summer. I did that for over 4 years. Bet you can't beat that.

[Bob Shaw]

ok..I took a screen capture of the jan 26th briefing..but not sure how to put in the picture lol
I got it from spaceflightnow clip..near middle of page..I'm sure there is a larger version somewhere


edit.: ok I'm an idiot...didn't look low enough lol

Is it just me, or does that MSL mock-up look, well, scary? I pity any poor, peace-loving Martians who see that coming over the brow of a hill, laser 'sampler' firing away. It looks like a praying mantis... ...now we know what *really* came out of those egg-things the Soviets kept dropping on Mars back in the days of yore!

Bob Shaw

[hendric]

I hereby nickname MSL "The Skunk".

[dvandorn]

If what kills the MERs is broken wires caused by movement in a thermally hostile environment, then they are going to have to do some clever work to stop the same thing killing MSL.

The MERs were truly not designed with the thought in mind that the exposed wire bundles would have to suffer through more than 800 thermal cycles as severe as those seen on Mars. Remember, right up until the girls just kept performing normally well past their design lifetimes, their builders and handlers expected to get 90 sols out of them. Anything beyond that would be gravy -- so they didn't take long-term survival into account in their design. At all.

I'm sure that there are tricks you can use (like using wire and insulation with the best low-temperature ductility and flexibility you can find, as well as designing your wiring paths to reduce to the bare minimum the amount of wire flexing you induce in normal operations) that the MSL designers will at least consider in trying to ensure their vehicle remains in perfect operating condition for at least one Martian year.

If they do their jobs as well as the MER designers did their jobs, we could see MSL last for several Martian years. But we need to build it, launch it, and get it safely down onto the Martian surface first.

Don't eat your peanuts before your bird flies, boys...

-the other Doug

[chris]

Um yes. Well put

Chris

[nprev]

I used to drive a 74 Vega in and around the cold of Bozeman, Montana and then home through the Mojave desert to Los Angeles every summer. I did that for over 4 years. Bet you can't beat that.

Mmm..not bad, but did you ever take it on I-90 through Butte, MT in February? -35 to -50 deg F was not an uncommon nighttime low there at that time of year back in the day.

In fact, Butte might not be a bad choice for a CONUS Mars diurnal climactic cycle simulation site in many ways...the average is eight (8) frost-free days per year & it can reach 85 deg F during summer days according to the NWS, plus there are abundant locations for dispensation of adult liquid refreshment...

[tty]

Every aircraft operating in the tropics has to stand thermic cycling from about +50 to -50 Celsius for every reasonably long flight. This goes on several times a day for decades and aircraft have lots of wire bundles and moving parts. So I think building mars rovers to ordinary aircraft standards and materials should probably do the trick. The main problem with thermal cycling in aircraft is condensation which causes corrosion, and this is not likely to be much of a problem on Mars.

tty

[Guest_BruceMoomaw_*]

That uptilted box on the rear of the MSL model is to cover up the RTG -- it didn't exist on the earlier drawings. Question: will it really be there, or is this a fig leaf to cover up from the general public the fact that MSL will carry an RTG, to try and diminish anti-nuclear protests? (Kind of like those clothes Att. Gen. Ashcroft insisted on putting on the nude statues in the Justice Department building.)

[mcaplinger]

That uptilted box on the rear of the MSL model is to cover up the RTG...

Umm, no, that's the heat exchanger for the fluid loop that carries RTG waste heat into the rover.
See http://marstech.jpl.nasa.gov/publications/...-2005-01-28.pdf

[Bob Shaw]

Umm, no, that's the heat exchanger for the fluid loop that carries RTG waste heat into the rover.
See http://marstech.jpl.nasa.gov/publications/...-2005-01-28.pdf

Nah. It's an ovipositor. For implanting those nasty eggy things into poor, defenceless Martians. Scawwwwwy Earth monsters!

Bob Shaw

[Guest_BruceMoomaw_*]

Umm, no, that's the heat exchanger for the fluid loop that carries RTG waste heat into the rover.
See http://marstech.jpl.nasa.gov/publications/...-2005-01-28.pdf

Hmm. Well, the drawing on page 2 of that paper certainly doesn't look much like the shape of that thing in the MSL model -- you can see the RTG very easily in the latter, but NOT in the former. In particular, in the drawing there's no evidence of the flat rear cover plate which exists in the model and shields the RTG from view. (In fact, the silhouette of the combined RTG and radiator-fin assembly on one diagram of MSL as seen from the front led one earlier contributor to this site to enquire whether Batman was hitching a ride.) Is it still possible that JPL did a little fiddling with that model for the press conference to cover up the RTG, or is it just the result of a different viewing angle or a system redesign?

[mcaplinger]

Is it still possible that JPL did a little fiddling with that model for the press conference to cover up the RTG...

Anything's possible, I suppose, and the image of the model is too low-res to see much detail -- I think I can see the RTG radiator fins on the bottom, and I can't tell what's on the top. For all I know, the modelmaker was in a rush or didn't do a very good job.

If you want to be annoyed about something, be annoyed by the stupid airbrushing-out of the RTG on the renderings.

[Matt Francis]

Hmm. Well, the drawing on page 2 of that paper certainly doesn't look much like the shape of that thing in the MSL model -- you can see the RTG very easily in the latter, but NOT in the former. In particular, in the drawing there's no evidence of the flat rear cover plate which exists in the model and shields the RTG from view. (In fact, the silhouette of the combined RTG and radiator-fin assembly on one diagram of MSL as seen from the front led one earlier contributor to this site to enquire whether Batman was hitching a ride.) Is it still possible that JPL did a little fiddling with that model for the press conference to cover up the RTG, or is it just the result of a different viewing angle or a system redesign?

Well notice too that it's not a full rendering of the rover. A layer of architecture seems almost peeled away in that design diagram. The shroud may be a protective, insulative enclosure for the RTG more than an essential part of the thermal control system.

[mchan]

Is it still possible that JPL did a little fiddling with that model for the press conference to cover up the RTG, or is it just the result of a different viewing angle or a system redesign?

Well, the MSL summary on NASA's Mars website http://mars.jpl.nasa.gov/missions/future/msl.html still mentions at the bottom --

"NASA is also considering solar power alternatives that could meet the mission's science and mobility objectives. "

Maybe they did not want to make it look like the RTG is a done deal.