Mars Science Laboratory: Big Wheels on A Red Planet

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The article mentions Richard Cook as the project manager, so what happened to Pete Theisinger? I thought Cook was only deputy project manager on MSL with Theisinger being the Big Boss.
BTW, if MSL lives up to JPL standards it is not only a great way of closing this decade, it will still be driving around on Mars at the end of the next decade!

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JPL personnel promotions, February 2005:

Naderi from Mars Exploration Programs manager to a JPL Associate Director.
Li from MEP deputy to MEP manager.
Theisinger from MSL manager to MEP deputy.
Cook from MSL deputy to MSL lead.

Jim Erickson is currently the MER program manager.

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What a beast . Will its instruments be fine enough to detect things the size of Sojourner?

By the way do I remember well that the large MERs fitted in the same canisters as small Sojourner? I suppose they'll need a larger one to fit in MSL though .

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They're using a different landing mechanism for the MSL, something called a "Sky Crane." As I understand it, the rover is literally going to be landing on Mars directly, wheels on dirt, after being lowered via a tether from a rocket hovering above. This sounds scary, but it allows for a landing ellipse a third the size of the ones for the MERs.

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OK interestning idea!

I have found no source saying that the MER's indeed had to fit into exactly the same canister as Sojourner (hence the folding wheels and the like, IIRC).

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Thanks.
They sure like some job hopping there at JPL!

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I've been reading Steve Squyres' new book Roving Mars and he talks about this. They didn't have to fit into the same canister as Sojourner, but as the whole Pathfinder lander that included the Sojourner rover.

That was decided basic time and money reasons. If they sent their Rover to Mars based on an already-existing landing system, they wouldn't have to spend the time/money developing that and could focus on the payload.

OK Thanks for that explanation. It makes more sense that a MER would fit when you consider that Pathfinder and Sojourner were one package of course.

Still the MER's are fancy Transformers .

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Happy Birthday Cugel!

That skycrane gives me the willies. As a novel delivery system, I just hope the damned thing works--no second chance on this one.

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Yet another trip around the Sun. No problem!

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It gives me the creeps, bleeps, and willies too... It sounds... like a very bad idea. It especially sounds like a bad idea since this one will be nuclear powered "Hey I got a great idea everone!!! Let's use this crazy landing system with a nuclear payload so when it goes wrong we make Mars even worse off than it is!"

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1) How did the moon landers work?
2) if the rocket should act a bit different from hoped behaviour and the MSL falls to the surface from a height, do you really think that would cause the RTG to leak, considering it is strong enough to survive a launch explosion?

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Landing Sites Debated for Next Mars Rover

No specific sites mentioned, just a general discussion. Significant is that the new landing approach is more flexible than the airbags and allows for more possible locations.

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I too am concerned about the skycrane system. It looks like a neat idea on paper, but it seems like rather complex landing system. I just hope that it works as advertised. It would be very bad if the new rover crashes while trying to land.

While the Skycrane is a complex landing system, it isn't without precedent. For decades, the Soviets/Russians have used retrorockets to soften the impact of large air-dropped objects like trucks, tanks, and the like. They also use this system on the Soyuz. For the air-dropped articles, a wire dangles below the payload. When the wire contacts the ground, retrorockets fire to slow the descent rate. If you look closely at this poor quality video (about 2:08 into the presentation), you can see the smoke from the retrorockets just before an armored personnel carrier hits the ground.


On Mars (and perhaps on the Soyuz capsules), you'd be better off using a radar altimeter to measure the altitude and descent rate and to determine when to fire the retrorockets. It might even be possible to control the retrorocket firing by igniting varying numbers of small rockets depending on the descent rate (similar to how they can control the force of airbag deployment).

Still, the more complicated a system is, the more likely it is to break...

Everyone said that bouncing airbags was a crazy system too. Now people complain when a conventional landing is proposed, as with Phoenix.

Jon

Here is a nice PDF describing the various landing methods used on mars missions.

http://smartech.gatech.edu/bitstream...D0076FINAL.pdf
(on a slow server, so be patient)

It shows that Phoenix inherits its EDL system from MPL, that is 3 crushable legs and a pulsed propulsion system to control the descent velocity. According to the paper this is a cheaper solution than using the Viking approach with throttable engines. Some people have concerns that it is also much more error prone. The only reason I see why Phoenix doesn't use the MER airbag EDL system is because it is build by Lockheed-Martin and not by JPL. After 3 succesful landings in a row, it seems questionable to do otherwise just because of the 'not invented here' syndrom.

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Another, very good reason is the airbag approach has very little growth potential. The MERS are at the limit. It is very limited with respect to issues like cross winds and surface roughness. Lastly, it is incapable of precision landing.

Since we want to land larger space craft on Mars in more exciting places we will need these capabilities which can only be achieved using either skycranes or a convention legged lander. In the long term legged landers are the way to go I think. My concern about the skycrane is what happens if the cable isn't cut and the skycrane does not fly away as it's supposed to. But the appraoch is said to be lighter than the alternative, and there are, I believe alternative designs available if it does not prove to be workable.

Also the airbag systems have been successful only 3 out of 4 times. Beagle 2 used airbags and there were a number of concerns about them. Spirit came close to being lost through cross winds. The Russian landers also used an airbag system, albeit of different concept, and were not particularly succesful.

Jon

Not to forget that Spirit came very close to a crash when the Mars atmosphere turned out to be even less densier than expected. Still, I think Phoenix would have been a good candidate for an airbag EDL system.

The advantage of the skycrane over a legged lander will always be that it greatly reduces the amount of mass that actually touches down. According to the specialists on UMSF that is a critical design parameter, which is not so strange since F=m*a. I'm not so sure if failing to cut the cable is such a risk increase. It will be done by a pyro device and MER depended on over 50 of these things for succesful landing and deployment. Having one more doesn't seem to add that much risk. Maybe it's actually better because the rover doesn't need any deployment at all after touch down, so it can do with less pyro and other fa