2009 Or 2011 ?, 1 or 2 ? Options

[Redstone]

MSL, with all of its instruments selected, is on track for a 2009 launch. There are a lot of rumors flying regarding a slip of MSL out to 2011. To repeat, MSL IS on track for 2009 and I consider this a FIXED milestone. That is, I will expend the necessary resources to keep it there.

Source is here, page 4. No mention of a second MSL.

[dvandorn]

Maybe flying one MSL at a time is a good idea. Look how badly stretched and incredibly exhausted the MER Team has become, as their babies have survived far longer than anyone could ever have dreamed.

If it were up to me, if I had a mandate to fly a single MSL, I would build two of them and tell people we're going to use one as an engineering testbed. After a successful first MSL flight, we go to Congress and say "Well, jeepers, we have this whole second vehicle that's nearly ready to fly -- how about letting us launch it in 2011?"

That way, the MSL Team would only have to plan and execute an exploration plan for one mission at a time. I know we like all the data the dual MERs have handed us, but face it, it's been hard on the MER Team and their families.

-the other Doug

[Bob Shaw]

A second MSL which just happens to be available might meet with the same barriers as New Horizons 2...

A Sojourner in the hand is worth a Marie Curie in the bush!

[edstrick]

They *SHOULD* build a flight vehicle and a "refurbishable" engineering test vehicle. Ideally 3 MSL's should fly at successive opportunities.

Flying 2 identical vehicles in one opportunity increases chances for success, but also for identical failures. The Soviet Venera 11 and 12 landers both had essentially perfect missions till touchdown... and never activated their surface science payload. All they did for the hour plus <I think> they survived is transmit brief batches of descent science from surviving descent instruments <some only returned valid data at higher altitude before frying, as designed>, inbetween long periods of nothing from the inactive surface science payload.

If *I* had 3 MSL's, I'd put one down in Melas Chasma, one down in the geologically most complex and most exposed part of the Meridiani sedimentary complex, and a third down in the deepest part of the Hellas impact basin, where there's complex layered sediments that seem to show plastic flow patterns. There's just too much geologic variety on Mars to fly one and "be done with it".

Essentially identical vehicles could fly the first two missions, the third could have a major update of it's instrument package. If the first fails, it's likely that any simple fix to the design could be done to the second. If we had built 2 Polar Landers, a simple software fix would have probably resulted in a successful second mission. Granted there were additional design deficiencies, like no descent communications, but that could have been patched. A "parasitic" payload could have been attached to the 2001 lander relaying data to an orbiter as during the MER Landings, even if it was only accelerometer data from the parasitic status monitor.

[Guest_BruceMoomaw_*]

I think both that (A) flying more than one MSL is an excellent idea, and ( NOT flying more than one MSL at any particular launch opportunity is ALSO an excellent idea. It has now been made clear -- both at the Mars Roadmap meetings and the recent European Geophysical Union meeting -- that the main purpose of MSL is to locate trace organic compounds which might be biological at some place on the surface, so that the first sample-return mission (these will be expensive and infrequent as hell) can be sent to that same location.

But if the first MSL comes up empty-handed, we will not have any good idea where to send the SR mission -- unless we launch a second (or even a third) MSL which does find such interesting organics. And if the first MSL does come up empty-handed, it would probably be wise to take some time to decide on the best possible landing site for the second MSL (for which purpose the data from the first MSL will still be valuable).

NASA actually did briefly release the first draft of the Mars Roadmap several weeks ago -- and then almost immediately yanked it back off the Web. It has not yet been returned (whereas most of the other first-draft Roadmaps have been). But I copied it first.

The Committee does recommend unambiguously that a second MSL be flown, but presents two possible alternative sequences of missions in 2009 and 2011. In one, MSL-1 will fly in 2009, and MSL-2 and the first Mars Telecom Orbiter will both fly in 2011 -- which means that the first MSL would have to spend its first year on the surface trickling back data (and driving) at a far slower pace than would be possible with the MTO.

In the alternative scenario, MTO would fly in 2009, while both MSLs would fly in 2011. This seems to me far the superior plan of the two -- both for the above reason, and because, if the first MTO fails, it would provide time to launch a backup one (along with both MSLs) in 2011. (If not launched then, the already-built MTO backup could simply go into storage until it is needed -- which, if things go well, wouldn't be until 2018.) But this scenario does still have the other problem I mentioned: if the first MSL fails to find trace organics, it does not provide an interval to decide the most promising possible landing site for MSL-2 (for which the data from MSL-1, as mentioned, is likely to be important).

The Roadmap calls for the launch of the first of Bush's new "Mars Testbed" missions -- renamed "Mars Environment Mission 1" -- in 2013. (This could be either an orbiter or a lander, depending on which investigations are considered most urgent for the purposes of planning a later manned Mars mission -- its design should be picked by 2008.) It also calls firmly for the launch of the Sample Return mission in early 2016, and "no later". Even if we do that, though, then why not launch MTO-1 in 2009, MSL-1 in 2011, and both MSL-2 and the MEM mission in 2013? We may well end up seeing this sequence anyway, if the Mars program runs over cost (as is virtually predictable) -- and even if it doesn't do so, it seems to me to make more logical sense.

(Two Mars Scouts are called for at some point in the 2009 to 2013 windows; there's a lot of flexibility as to how they could be fit into any of these scenarios. If MSL-1 isn't launched in 2009, the first of these Scouts would definitely fly in 2009 along with MTO-1. It might even provide highly useful additional data in picking the landing site for MSL-1, if it's a trace-gas or water mapper -- and while the Committee doesn't make any firm recommendation, they do suggest that a trace-gas mapper might be the best choice for the next Mars Scout.)

As I say, the Sample Return missions will be so hideously expensive and infrequent that it is absolutely crucial to maximize the chances of their turning up biological evidence -- so a delayed launch for the first SR mission would seem to be much, much better than an overhasty one, despite what the Roadmap Committee says.

[edstrick]

Missions failures are most often at launch or arrival. Arrival for a lander tends to be a *lot* more likely to cause a failure than for an orbiter.

Granted, the soviets had Mars-4 fail orbit insertion in '73, the US lost Mars Observer during arrival preps in '92 <I think> and Climate Orbiter in '99, and the Japanese had Nozomi fail orbit insertion in '03 after inflight damage from solar storm radiation. But compare that to the US and Soviet/Russian losses in Mars mission launch and landing attempts.

For the '09 opportunity, doesn't the Telecom orbiter launch first?... Orbiters are constrained for a low approach velocity to the planet to cut down on orbit insertion fuel mass and normally launch before a direct-descent lander would.

I'd go for an '09 MSL. If I can't relay through current telecom on Odyssey and Mars Express, then it should launch with the provision that it automatically be mothballed for the '09 window if Telecom orbiter fails to be in good checked-out condition after launch, and be re-prepped for launch in '11.

[Jeff7]

Maybe flying one MSL at a time is a good idea.  Look how badly stretched and incredibly exhausted the MER Team has become, as their babies have survived far longer than anyone could ever have dreamed.

If it were up to me, if I had a mandate to fly a single MSL, I would build two of them and tell people we're going to use one as an engineering testbed.  After a successful first MSL flight, we go to Congress and say "Well, jeepers, we have this whole second vehicle that's nearly ready to fly -- how about letting us launch it in 2011?"

That way, the MSL Team would only have to plan and execute an exploration plan for one mission at a time.  I know we like all the data the dual MERs have handed us, but face it, it's been hard on the MER Team and their families.

-the other Doug

Thing is, if NASA only flies one rover, the team will be half the size to begin with, and they'll pare it down as the mission continues. In that event, by the end, they'd only have half the workload they have now, but they'd also have half the staff they have now.

[Cugel]

As I understand it there are 2 options: a skycrane or a descent stage with the rover on top. The last option having the problem of driving of the lander. But did they ever consider the simple solution of attaching the descent stage directly ON TOP of the rover. What is the problem with this Viking-like approach? After the landing you simply blow a few pyrotechnics and dump the tanks and nozzles of the descent stage on the ground... and drive away. There is no problem of 'disturbing' the landingsite with exhaust fumes because you're not staying there anyway. And with the descent stage and rover firmly connected into a single machine during landing you have complete control over it. Or, put in other words, what is the big advantage of the skycrane over such a simple solution?

I know I'm missing something here... but what is it?

[Marcel]

I know I'm missing something here... but what is it? 

Um, well, maybe you forget about the fact that it is not just dumping nozzles and tanks....it's the whole descend stage you have to get rid of. You can't just bolt tanks and nozzles to a delicate rover with it's fragile mobility system hanging under, exposing it to an impact that cannot be controled the way it can be controled on a tether. It even makes sense to let the rover down under a sky-crane AND deliver it to the surface on a shock absorbing platform. Or at least: you have to make the rocker-bogie more rigid to withstand the impact to prevent the wheels to end up besides the rover instead of right under. A temporarily inforced construction that connects the wheels to the chassis with pyros might be a solution as well.

You first need to hover to (almost) a complete stop, then lower it gently to the surface, then let the crane fly elsewhere.

[Marcel]

Cugel, there's also another thread about EDL for MSL....."skycrane: innovative landing technology"....continuation better be done there, before our iron fisted administrator kicks us out

[Cugel]

Cugel, there's also another thread about EDL for MSL....."skycrane: innovative landing technology"....continuation better be done there, before our iron fisted administrator kicks us out 

OK! Switching..3...2....1....

[Guest_exobioquest_*]

I hope wikipedia is up to date on this: http://en.wikipedia.org/wiki/Mars_Science_Laboratory
simple put as: "As of June of 2005 Andy Dantzler, director of NASA's Solar System Division has stated that MSL it is on track for 2009 and he will expend considerable effort to make sure that date is not changed." Has anything come up since then, publicly or not?

By the way I personally think sending 2 MSLs in 2011 is very risky! I have great faith in the skycrane (sure is completely sane compared to the airbag-bounce landing and that worked!) but being un-tests if we sent 2 rovers and they both suffered from some design flaw that’s 140% of the money gone and 200% the PR damage for NASA compared to losing 1 rover in a singular mission. If you look at the history of mars space probes it's most often two identical probes are sent and they both work, or they both fail, not 1 out of 2. So one at a time until we know it works.

[edstrick]

The Soviet Venera 11 and 12 landers performed nominal missions through atmospher descent (returning excellent science) until touchdown, when both -- IDENTICALLY -- failed to turn on post-landing instrumentation and activivies.
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What is better than flying two of one kind at the same time is to build more than one, and fly them at 1 opposition intervals. If you design *reasonably* well, most screwups don't require total mission redesign and can be "patched" before the next launch opportunity.

I don't know what the Mars Program reorganization Bruce Moomaw is promising us we'll learn about in his Astronomy article (was it?)..... What I'd like to see about 3 total MSL missions, with a third possibly having a re-selected set of instruments. They'd be sent, as with the current rovers, to as fundamentally different geologic regions as possible within the constraints of focusing on the Martian history of water and potentially life-supporting environments.

NorthEast Meridiani, in the area of greatest differential stripping of layered sedimentary units is an obvious candidate. The Melas Chasma candidate site for the MER-B is another, with spectacularly varied geology plus scenery that rocks. I've been somewhat surprises at the little interest in the layered deposits of Hellas planitia. A potential site might be the lowest place on Mars, NorthWest Hellas, with access to basin floor sediments and cratered highland deposits of the rim (driving might be a bit long-range) I don't want to try for a 4'th time at outflow channel deposits, having failed to find "of interest" with Viking 1 in Chryse, Pathfinder in Ares Vallis, and MER-A on the basalt-covered plains of Gusev

[Guest_BruceMoomaw_*]

Unfortunately, I still don't feel I can give the information away for free quite yet -- although in another few days it may be a different matter. I will say that the new plan involves something generally similar to at least one more MSL mission, but with a lot of flexibility in the overall mission design.

[edstrick]

When you're playing it smart, a lot can be done to redesign, even rebuild a spacecraft for an "equivalent" new mission in a relatively short time and at ridiculously low cost. Look at Venus Express, finally sending a "Mariner class" orbiter to Venus for studies that should have been done 20 to 25 years ago.

Another example from Venus: The engineering spacecraft from the Mariner Mars 1964 mission was redesigned and rebuilt as Mariner Venus 1967. The main changes were reversing the solar panels, nuking the camera system (of dubious use for Venus even with plausible modifications), and replacing it with a receiver for dual channel atmosphere occultation measurements to supplement the S-Band occultation carrier transmitted to Earth.

The occultation didn't reach the surface due to atmosphere refraction, but it proved that Venera 4 (arriving a few days earlier) stopped transmitting before reaching the surface, and together with the Venera 4 data, showed the surface would be encountered at around the 90-100 atmosphere level, where it turned out to be.