Found UMSFer Edwin Kite's presentation to be very interesting. He's performing a valuable service- forcing people to question romantic assumptions about Martian sedimentary rocks. Is he the new Nick Hoffman?

I truly do not see where this comes from. Light-toned layered deposits. Phyllosilicates. Fluvial channels within the driving range. And the complicating factor in the ellipse is alluvium (with ripples), not basalt. This is not one of my favorite sites .. but "like Gusev" misses the mark.


It would be great to get to the top. But you're right, MSL likely won't. But the science targets are reachable, and the driving to get there is easier than at Mawrth.



Hmm. Everything in the ellipse. Well, mostly--the sulfates are outside the ellipse. But that's very different from everything at your landing spot. Especially with slow traverses. If Go-to capability is somehow limited, it hurts a Mawrth investigation less then the other sites--it does not let Mawrth off the hook.



Don't sell the mound short. It looks down on Pike's Peak. By a factor of 3. Peak altitude with respect to the mean datum is irrelevant--by that standard, Gale's mound is a bump; PP much taller. Stand at the base and look up. The mound is Mt. Logan; or Mt. Rainier on steroids (in size, and a little bit in shape--of course it is layered sediments). From the base, it is 5 km of exposed sediments, not a paltry 1.6 km ;^) . That said, of course MSL's investigation will be vastly less than 5 km; but there would be some pretty pictures.

Separately, I agree with Jim Bell. We have the capability to drive, to "go to" a site out of the ellipse. We should use it IF it gets us what we want, and that should be decided on the merits. The rallying cry should not become, "Why settle for the best when you can hold out for good enough." Many think Mawrth is best, and they certainly don't want to settle. But the Ruff-ian argument that those who favor other sites should forsake go-to as soon as Mawrth gets over some "good enough" bar -- well, that should waste the patience of explorers.

I'm still GO for Mawrth!! Lets get down to business straight away and not waste time driving .....we'll have time to study ancient martian history which we havent done yet from the ground..done with that, we can then drive to other sites provided the goals are met early in the mission.. all extra will be bonus!! Besides we dont have any guarantees the mission will last as long as MERs

If that were the case, we would be sending a lander. Mawrth, as with all the others, has specific targets that require driving. Moreover, all the sites have good science within their landing ellipses. Mawrth is not special in this regard.



We DO have a requirement for 2 years on the ground. All of the sites driving requirements and science requirements can fit within that time span.

They are essentially indistinguishable in terms of scientific merit and EDL safety.

Well said, Doug.

To me, it all comes back to a careful read of the stated science goals. Somewhat unfortunately, this isn't much of a discriminator; Mars has a very rich history as is increasingly revealed by MRO & other orbiters, reinforced by the ground truth of the MERs. On top of it all, the EDL system is purportedly robust enough to handle any of the four finalists

I can well understand the indecision. If we were to land on Earth, where would we go to achieve maximum science return? I don't even have a clue. Mars is not as environmentally diverse as Earth, but it's a hell of a lot more diverse than we originally thought not too long ago.

There's probably not a right answer. All remaining candidate sites have something to offer. Therefore, to be utterly pragmatic & honest, it's time to ask the engineers. They apparently are saying that they can set MSL down anywhere the scientists want it to be, but surely one of these sites is easier than the other three iin some respect. I suggest that they should be consulted for a high-res look at exactly which site offers the least landing risk if there are no other compelling discriminatory factors.

Bottom line is that there's gotta be a choice made soon. MSL has the potential to conduct a regional survey of its landing site. Which area would provide the maximum information with respect to the major questions about Mars and its history given that capability?

Of course I expect some driving to get to targeted sites but driving 1 km to get science is certainly preferable than having to drive 30km!! Requirement for mission success is 2 years for MSL which is more robust than MER... yes I see your point Doug but it doesnt mean that it will last that long.....dont get me wrong, I wish MSL all the success and better science returns than MER but you never know what MARS may hold for MSL!!??

I'll repeat myself : The sites all have interesting science within their ellipse, and, repeating myself again, Mawrth involves driving to science targets as well. Your entire premise is flawed. You clearly have not read the presentations that the landing site meeting put online.



So how long do YOU think it will last. What assumption are you going to make about its lifespan that drives your preference to Mawrth. What drives your decision to think you know how long the vehicle will last better than the engineers responsible for designing, building, testing...and driving...the vehicle? The level 1 requirement is 2 years. To make ANY assumption regarding longevity other than that is folly.



Yet you're making assumptions about Mawrth, and indeed the other sites, that the data simple doesn't support. If you wish to make a case for Mawrth, then you need to demonstrate that it is scientifically more attractive or safer to land on or drive around.

The project scientists and engineers were basically unable to do that.

This is a beginner's question, quite possibly asked and answered before. Suppose Curiosity were heading with few distractions toward a distant target much as Opportunity is now, what distance is it expected to cover in one good day?

I'm hoping MSL will last a lifetime! I'm not in a postion to judge on the eventual site selected and I trust that the engineers and scientists will make the best choice at the end. All I am saying is that I prefer Mawrth for the simple reason that it represents the earliest Martian history compared to the other sites. Its like reading a book..u want to read from the start rather than start from the middle section for it to make more sense. This is my judgement. Whether I am right or wrong I'll leave it to the people directly involved in this decision.I'll be happy with whatever they decide. At the end of the day what counts is that we'll have another Mars mission to follow for years to come and that makes me excited wherever it happens on Mars!

I've been loosely following this discussion and the debate around the choice of the MSL landing site, so maybe my comment is ridiculous, but anyway...
If all the sites are equally rich scientifically, I suppose that means the interesting stuff at each site is accessible within the 2-year mission requirement. Of course, we don't know in advance if there will be any mission extensions. We can only hope. Or if MSL will die before 2 years on Mars (heaven forbid!). In any case, would it not be a good idea to plan a little bit in advance? We could take as a hypothesis that MSL will last longer than 2 years and ask ourselves: once we have studied the landing zone thoroughly, where do we send the rover? Suppose at one site the next interesting geology is (say) 50 km away, and at another site 20 km away (just throwing numbers around), then if all 4 sites have equal scientific merit, why not send MSL to a site having a higher "concentration" of various interesting geologic features?

To say that "To make any assumption other than [the design requirements] is folly" is not entirely accurate. If I may reference a manned program, remember that the first task that Neil Armstrong had upon getting onto the Moon's surface was to scoop up a contingency sample in case something unforeseen went wrong and he had to get out of there quickly. The design requirement for the LM was to stay on the Moon for 24 hours, but prudence dictated preparing for the unexpected.

Given the investment in the MSL platform and that there's just one shot at getting the science from her, prudence would seem to dictate putting her as close as possible to the priority targets of interest within the constraints of EDL etc. and not assuming that just because she's designed to last 2 years, she will necessarily have that long.

Just one person's view, but I think it would be be good to lay off the landing site discussion. I live in Wales, FWIW.

A quote from The Planetary Society Blog, Sept. 2010 (and a comment to that blog):

"Sean Haggart, the mobility engineer doing the narration, mentioned in the video that Curiosity's top speed is 4 centimeters per second, which is actually slower than what I've heard quoted for Spirit and Opportunity's top speed (5 cm/sec)."

"I remember a JPL lecture in which it was stated that the maximum blind-drive distance per hour for MSL is 210-m, versus 180-m for MER.
#3 - Bob Ames - 09/21/2010 - 04:55"

So Curiosity really doesn't travel any faster than Opportunity.

The remaining factor is how long Curiosity can drive. She has more power than Opportunity, but it takes more power just to move that hulk. It may end up being a wash, with Curiosity not consistently outdoing Opportunity's best pace. It will be interesting to see how long Opportunity holds on to her Mars distance record.

How long do they have to decide on the final site? Could it even be left for after launch, or do course corrections and such have to be planned out way ahead?

I believe that it does have to be decided before launch, since MSL will be on a direct trajectory to Mars just like the MERs, Phoenix, and Pathfinder. (The Vikings were in Mars orbit first, so they at least could select from sites achievable from their orbital planes.) Don't think that the cruise stage will be capable of doing anything but minor course corrections & attitude adjustments.

My understanding is that it WILL be decided before launch but that there is also an ability to re-target the landing site in-flight, though it does start to affect the size and shape of the ellipse as time goes by.

Dig it. I suspect that retargeting is far from the most desired course of action, though; not only would it cost considerable enroute consumables, it would also decrease landing precision as you described, Dan.

Curiosity will be active at night (and in the shade too). Of course they might not want to drive at night :-) but does Opportunity really manage to drive from dawn to dusk or is it only some fraction of daylight? Also, I'd expect Curiosity can do at least some science at night that Opportunity is forced to stop for during daylight hours.

Add all these factors together, and I expect either a) Curiosity manages maybe 2x the speed of Opportunity or Curiosity goes places Opportunity couldn't attempt.

one of the presenters with, I believe a Gale crater paper,presented a proposed route along with the geology to be found at each elevation.
Gale
if indeed all of these sites have compelling scientific merit, then there is one more factor to be considered,
The impact of images returned to the public imagination!
I remember watching on TV the Apollo 8 mission, and the earth rise photographs.The Gale creator presenter promised a compelling scenery, perhaps it is this consideration that should be added to the final decision.
the public so engaged might very well influence future decisions on planetary exploration.if all 4 candidates are scientificly compelling and are equaly safe for landing, Is my landing elipse safer then yours? then pick one that holds promise to excite the public imagination to ask for more funding for future exploration.
Hubble is an example of such a machine that excites the public imagination.

Oh, the oft repeated and oft corrected myth. Curiosity will have a power budget just like MER. Just because it's got an RTG doesn't mean it's awake 24/7. It'll be asleep at night, just like MER. What MSL will be doing at night is recharging its batteries. Moreover, in shade - it'll be colder than average and thus require even more actuator heating (already a significant power budget burden)

The RTG renders the power supply more reliable. It doesn't render it infinite.

Again - if that's the case, send a lander. We've spent a fortune making a mobile vehicle...yet you're advocating not using it. It's like dangling keys infront of the science team, but not letting them use them. Moreover, again, all the landing sites have good stuff within their ellipses, and Mawrth would require driving just like the wrongly titled 'go to' landing sites.

Except that the RTG is generating much more heat than power. Even if it's charging its batteries, it ought to have a lot more heat available than the other rovers ever did. I'd expect getting rid of that heat would be a big problem. I'm surprised if it'd need to actually use electric power to heat anything.

Of course, I've been surprised before . . .


--Greg

Then be surprised. Mobility heating represents a significant portion of the daily power budget. Indeed some previously considered landing sites were expected to be so cold that there would be significant no-drive periods as the mobility heating requirements would be so bad, they were unsustainable. This is covered in earlier landing site selection meeting documentation.

Yup - by the 3rd landing site meeting, they had established that they could target any site between 30N and 30S by targeting at TCM1.

Come to think of it it really is TCM1 not launch that is the drop dead date. Though the decision will be made and announced before then I am sure. At launch the space-craft is targeted slightly away from Mars so that the third stage of the rocket doesn't hit the planet. It's too big to sterilize and everything that hits Mars has to be relatively clean of bacteria according to the Planetary protection guidelines. Thus it's only with TCM1 that the spacecraft is aimed directly at Mars at all giving a fairly wide choice of landing sites from any single launch profile.

"...a pump system similar to a car's radiator. The pump circulates temperature-regulating fluid through the rover's body with 200 feet of tubes.
.... On Mars, the pump must run constantly, and if it failed, the rover would die."

Oh, great. One more failure mode to worry about.

I get the impression that following the MSL's progress through it's mission will have the same temporal feeling as following the MER missions. The MSL will not move from spot to spot any faster. And there will always be energy restraints placed on how fast science can be done at any one spot. Of course MSL can move into much more challenging terrain than MER and do a lot more science, but I think we will experience the same level of "are we there yet" and "when will we be moving on" feelings as we do with MER.

MSL produces about four times as much energy as the MERs, but it weighs over four times as much. The science payload, I'm sure, uses at least four times as much energy as the MER payload on average. So the energy budget restrictions for roving and science should be about the same for MSL as for MER.

Click to view attachment
http://www.usatoday.com/tech/science/space...4-13-mars_N.htm

This topic has been split at the point that the downselection to Gale was made. Discussions of Gale Crater as the MSL landing site are now here.