Phoenix is important as a GRS groundtruth for near sub surface ice. It's work that needs to be done as part of the grand scheme of things.

Doug

Bruce said:

"As a way to investigate Meridiani (as was originally planned), Phoenix would have been a fiasco. "

I hadn't heard this about Meridiani. Can you tell us more, Bruce?

Phil

With the way the program works, I would add that we are thinking falsly if we think that "hmmm...., instead of Phoenix, why don't we save up a few more years for a bigger mission?" If we didn't launch Phoenix, that money would probably be allocated out of the Mars program. And without Phoenix, the Mars program would currently have no projects in advanced development, making it a dangerous target for budget cutters.

And I don't agree with the three days to a month analogy. It is more like going to visit a college before deciding to go study there. Sure, Phoenix is limited in scope, but in addition to doing good science, it will help us prepare for when a real drilling mission like Mars Deep Drill is designed. Sort of like how Pioneer was sent to scout for Voyager. The Pioneers made many discoveries in their own right, but also did a lot to prepare the way.

I think he was referring to the fact that this was going to be the site for the Mars 2001 lander. It might have been frustrating, but not if it landed where it did. I think Marie Curie, which would have flown on that mission, would have at least been able to explore the Eagle outcrops. And such discoveries might have allowed for MER to carry better-suited instrumentation (actually, probably not much, given the lack of time between the missions, unless one of the MERs were delayed. But for Phoneix, there is a much longer gap before the proposed drilling mission).

Yeah -- it was actually sloppy language on my part; I was referring to the originaly planned mission of the 2001 Mars Surveyor Lander (after they stripped it of its REAL initial mission of being the landing platform for an MER rover. As a stationary lander, its ability to study the phenomena of Meridiani would of course have been pathetically limited, and the additional data its MECA package would have obtained would not remotely have been an adequate exchange for that loss.

But, regarding Phoenix: inspection of the Martian ice -- as soon as possible -- is a very important goal in the overall program, and one that simply cannot be done with MSL because of the limitations on its landing latitudes. We need to know more about the potential that the ice may have as a domicile for extant Martian microbes -- and we need to know more about Mars' climate cycles, both over periods of just a few years and over its 150,000-year long obliquity cycles (as ice is repeatedly deposited and then removed again from various latitudes). This mission is the perfect way to do that relatively cheaply and quickly. Any time you're tempted to gripe about it, just remember what I said earlier: this is the very FIRST biological space mission to another world since Viking. If it finds complex organic compounds in the ice, it is going to get extremely interesting extremely fast.

Yes, but it had Marie Curie, with a properly-set-up and brush-equiped APXS, had it landed where Oppy did, it could have done a lot of science. Not as much as an MER, but it definitely wouldn't have been the waste you describe.

While I agree with Bruce on the importance of these topics, there is a substantial chance that Phoenix's results will be inconclusive about both them and any biology. Just as with Deep Impact, this is a new terrain that we know very little about. Any of many factors -- like landing a few meters away from the right site or some type of soil gardening that erases context -- could prevent us from learning much about these goals.

That said, I think it's worth the effort. We need to take risks and then not blame the spacecraft team if we get skunked.

I agree. I know there are those who insist that we should send a mobile vehicle with a large drill that can also take more samples, etc., etc. Well, while we're at it, why don't we put a manned module in orbit to control the rovers in real time. And, add sample return capacity, of both soil, rock, and ice cores. Sure, there are limitations of the mission thanks to budget, but that is just reality.

I suspect that dismissing the importance of roving capability on Europa will turn-out to be short-sighted. We have pretty-near zero experience on the surface of an icy satellite (barring those fuzzy pics from Titan, which isn't a conventional icy satellite). At the very least, surface ice is likely to have originated from the internal ocean, and analysing the ice could reveal evidence of organic chemistry and (perhaps) life. It may be useful to have the capability to drive a few kilometers to find more recently exposed ice, and who knows what interesting "eurology" might be encountered.

Detection of relatively recently exposed ice -- or, more precisely, ice with a lot of other stuff mixed in (particularly organics) -- is indeed important, but the current emphasis is on doing it from orbit and then dispatching landers to those spots to probe it vertically.

what impact will the descent thrusters have on the soil it ends up landing on?

Probably a bit less than if they turn the suckers off too early again!

Hehe.

http://www.space.com/businesstechnology/05...oenix_tech.html

Which says it is of major concern to the science team.
How could they NOT have thought about this before ?

"As the ice starts advancing off Mars’ northern polar cap and moves southward, Phoenix will become entombed in several feet of solid carbon dioxide. The lander is not designed to survive being buried in solid ice for six to seven months, Smith said."

LOL - didnt think it would be that bad!

The exhaust plume contamination of local soil was something I read about w.r.t. MPL years ago - so I'm sure it's not something they've just thought of.

Doug

Ah, that's good to read. But what can be done ? Nothing i'm afraid.

I think the physical disturbance of the soil (stripping it's top layer) is probably not such a big issue. The real fear of it probably lies in the detection of organics and the interference that hydrazine and by-products could have on the measurements within the chromatograph column. I don't know enough about the field to know if this can be subtrancted easily from the rest. Probably the mix of unburned fuel and the products that are left after combustion are a very complex mix of organics that are hard to distinct from (possible) original (Martian) soil organic matter.

The ice layer of a meter or so also surpises me highly ! The thing will probably not wake up afterwards. It would surprise me if it did......maybe it's like freezing wet laundry:if it thaws without motion, it's intact afterwards. If it is moved (especially cables) in a brittle state, it snaps instantly. Don't know at which temp. this happens for the materials used. And most probable, the electronics itself will not survive months of exposure to -120 C. Does it have radioactive heaters like MER ?

The Phoenix's probably specific landing site will be selected based on detailed reconnaissance of candidate sites still to be conducted by spacecraft orbiting Mars. The
candidate sites will lie between the northern latitudes of 65 degrees (the equivalent of Fairbanks, Alaska) and 75 degrees (the equivalent of northern Greenland).
I am not sure if that by that zone there is permafrost snow because according to the following URL http://phoenix.lpl.arizona.edu/science/ shows that above than 80 degree has a greater change of abundance of water. Will Phoenix land on nude soil or ice surface?

About the budget of Phoenix is not considered as a cheap mission comparing to MERs ones:
Phoenix's relatively low cost: $US 386 M with 90 days of high activity (primary operations) and other between 30-60 days of low activities (meteorological station). and the MER costs with $US 400 M each one with 90 days of high activity mission.

The difference is around $US14 Million.

The extract from the dailyspace news:


Is it worth that the Phoenix has own mobility with the $US 16 M as the MER but with four hidden band rovers which will push down after landing in order to move away from its landing place in order to avoid the laboratory misleading analysis results?

Rodolfo