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Posted by: mars loon Mar 21 2006, 11:39 PM

A revealing new comparison image of MSL and MER

The JPL caption and article are below



This artist's concept shows that the next generation rover, Mars Science Laboratory, is much larger than Spirit and Opportunity.
Credit: NASA/JPL-Caltech

Setting Expectations for Future Generations

That's important, because the rovers depend on sun intake for their health. Like many boomers, they will be seeking the sunniest places to face winter, which is once again approaching on Mars. Having already lasted over a martian year - almost nine times longer than planned! - no one is sure just how much longer they will last.

"Once the rovers stop working, I'll miss seeing new pictures every day, but since I don't consider myself ancient, I hope to work on the Mars Science Laboratory mission after the rovers die," smiles Matijevic.

And, as new generations of rovers continue driving faster and farther on Mars, future generations of astronauts--perhaps the grandchildren of today's Baby Boomers--will begin to head farther away from Earth. On the horizon is a whole new era for a human-robotic partnership, with the young-at-heart rovers raising the bar for all who follow.

Posted by: PhilCo126 Mar 22 2006, 01:15 PM

I've read somewhere online that MSL might be nuclear powered so it could probably operate much longer possibly up to a decade ( remember the Viking landers )
Philip

Posted by: chris Mar 22 2006, 01:40 PM

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.

Chris

Posted by: djellison Mar 22 2006, 02:14 PM

When you've got yay-kW of heat sitting on the back of your rover, I suppose your could pipe it around to keep everything nice and toasty


Doug

Posted by: Chmee Mar 22 2006, 02:24 PM

Strange that this illustration of MSL (and many others), do not show the RTG off the back. It's almost like they do not want to draw too much attention to it. Mmmmmm...

Posted by: mcaplinger Mar 22 2006, 02:24 PM

Sadly, not as easy as it might sound. That'll be done for the main body of the rover, but stuff mounted on the extremities (wheels, mast, arm, etc.) is pretty much on its own. And electrical power for heaters, while available, is not all that plentiful. Surviving the temperature cycles is still a big challenge.

Posted by: odave Mar 22 2006, 02:38 PM

...and I figure the lack of solar panels in the image is a graphic form of Pig Latin from JPL- "Oweredpay ybay RTGay. On'tday elltay ethay ublicpay".

Posted by: jabe Mar 22 2006, 04:56 PM

mmm..
If my recollection of a press conference a while ago where they had a mockup..I thought the body of the msl was a "V" shape..anyone have screen shot somewhere of the MSL?

Posted by: chris Mar 22 2006, 05:09 PM

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

Posted by: djellison Mar 22 2006, 05:13 PM

Hostile - maybe some of the deep oceanic drilling equipment, but even that can get pulled up and sorted out - it probably sits at 4 degrees all day every day. Perhaps some of the equipment they have at the Antarctic Research Stations

But Hostile like Mars? Long-duration balloon experiements perhaps, but to be honest, I can't think of a long duration analogue on Earth.

Doug

Posted by: odave Mar 22 2006, 06:16 PM

It seems to me, given that MSL's http://mars.jpl.nasa.gov/msl/mission/tl_surface.html is one Martian year, and the fact that the MERs started having wire problems after one Martian year (with hardware designed for 90 sols), the technology is probably within reach. Of course, you'd want to build in enough margin for MSL to last >> one Mars year, and also consider the fact that MSL will be doing much more driving.

My company's got some robots operating in some very nasty and extreme manufacturing environments - more often in heat than cold, granted. But, like Doug says, the key is maintenance. Any machine has a decent chance at long term survival if there's someone around to do routine PM on it. Mars is a little remote for your average service call

Posted by: paxdan Mar 22 2006, 06:29 PM

Lunkhod 1 and 2 not as long as the mers, and in an arguabley more hostile environment

Posted by: jaywee Mar 22 2006, 06:37 PM

And did they put the HGA back? I remember seeing a design about half year ago which had only UHF helix and LGA.

Posted by: chris Mar 22 2006, 06:54 PM

Ah, thats a good point. They will put in some extra effort, then, which if the MERs are anything to go by, may last a good long time.

I wonder if making the bendy parts of the wiring loom with gold wires would help - it is amazingly ductile.

Chris

Posted by: BruceMoomaw Mar 22 2006, 08:34 PM

Oh, yes -- that big dish on a short mast smack in the middle of MSL's upper deck is the HGA. (Adding the direct-to-Earth radio link added a surprising amount of weight to MSL.)




There are overhead and front diagrams of it available somewhere, although I can't remember just where at the moment (I have them in my trusty CD-ROM file). But it always had a rectangular body shape.

Posted by: jabe Mar 22 2006, 11:07 PM

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 http://www.spaceflightnowplus.com/index.php?page=3&k=all&t=Recent+additions&s=posteddate..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

Posted by: ElkGroveDan Mar 23 2006, 12:18 AM

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.

Posted by: Bob Shaw Mar 23 2006, 11:17 AM

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

Posted by: hendric Mar 23 2006, 04:58 PM

I hereby nickname MSL "The Skunk".

Posted by: dvandorn Mar 24 2006, 03:46 AM

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

Posted by: chris Mar 24 2006, 09:28 AM

Um yes. Well put

Chris

Posted by: nprev Mar 25 2006, 07:14 AM

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...

Posted by: tty Mar 25 2006, 05:13 PM

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

Posted by: BruceMoomaw Mar 25 2006, 10:04 PM

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.)

Posted by: mcaplinger Mar 25 2006, 10:22 PM

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/Bhandari-final-paper-2005-01-28.pdf

Posted by: Bob Shaw Mar 25 2006, 10:31 PM

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

Bob Shaw

Posted by: BruceMoomaw Mar 26 2006, 03:58 AM

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?

Posted by: mcaplinger Mar 26 2006, 04:41 AM

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.

Posted by: Matt Francis Mar 26 2006, 04:45 AM

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.

Posted by: mchan Mar 26 2006, 04:48 AM

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.