ExoMars Options

[ustrax]

Sig!
It's a real deception...
Can we expect to make a real Mars exploration in these conditions? Whereas the European Union of the 25 is the first power of the world, just before the USA. But, European Space Agency is like a poor face to NASA.
2013... We can say never! We push, we push, we push and during this time, we can only dream by seeing the synthetics pictures of the rover (more build than the MER...).
This make me angry from the Europe. All this technocrates wo don't have any interest of the space and the science and who can prefer to pay there attention to... to what? So, this fact reveal clearly the Europe status : no goal, no way. No target are fix for the future. We can't stay with this semi-mesure Europe. A lots of project will stay write on the paper, in this time, America have landed on Mars with men and women.
I say it all the time : make the United States of Europe. Or stop it and come back to a pre-war situation when the countries made their own small project.

Sorry about that, but, for me, it's too.

Calm down Ant103...Maybe this step back can represent a turning point...
Who knows?
And comparing ESA's budget with the NASA one isn't fair.
You, and me, every european, contributes each year with the equivalent to a movie ticket.
Maybe it is time to stop and redirect the funds to a more pragmatic way of doing things, not depending on foreign knowledge.
There's one good novelty that cannot be forgotten in spite of this deception being taking our time and thoughts...ESA is asking for the SME's collaboration, and, in my humble opinion, that means advance.
Let's wait and see what's ESA response...

[monitorlizard]

I'm an American, so feel free to ignore this, but I sort of hope ESA simplifies ExoMars a bit. It's extremely ambitious for a first rover mission. We started out with Sojourner, which was quite simple compared to MER, but it gave us experience and confidence to build better rovers. I always thought the Soviet Union took the wrong approach to Mars exploration. They never proved that they could successfully carry out a simple Mars mission, yet they launched ever more complex spacecraft, all of which partially or completely failed. I fear Fobos-Grunt is another step along this path, but we'll see.

I prefer the building block approach to Mars exploration. ExoMars as currently envisioned will likely have a hard time miniaturizing its payload to target weight, and (if I remember correctly) would rely on very sophisticated artificial intelligence software. A somewhat simpler ExoMars could still do fantastic science, and I think would have a higher chance of success. And be more affordable.

But I'm basically conservative in these matters. In fact, I'm scared to death of MSL relying on Skycrane, which I don't think can be given a thorough end-to-end test.

[djellison]

"a thorough end-to-end test"

Viking 1, 2, Pathfinder, MPL, MERA, MERB....none had end to end tests...it's impossible to replicate the conditions on Earth in any realistic way.

Doug

[dvandorn]

Exactly, Doug. There are some things you *can* test end-to-end (like the software, for example), and this should always be done (would have likely saved MPL). But on some things, you just have to rely on engineering soundness. The engineering will either work, or it won't, and being thorough in your engineering studies and designs is the best you can ever really do.

Besides, most of the lost Mars probes were lost due to fairly simple mistakes. I'm reminded of that "Red Mars" set of animations someone put up on YouTube recently -- the one where the Red Rover and the Blue Rover are just standing around, talking, when suddenly a probe flashes overhead, burning up in the thin air, screaming "How many feet in a kilometer? How many feet in a kilometer?????"



-the other Doug

[helvick]

That's a bit of a sweeping generalization there oDoug. Of all the failures only the MCO english/metric units problem and the commanding error that led to the loss of Phobos 1 could really be called "simple". Out of 21 failures by the various participants in the Mars race I'd say that 2 cases caused by simple mistakes hardly deserves to be described as "most".

As to your other point they can and should test, test, test and then test some more where they can but at the same time we have to accept that there is a point where you have to stop chasing perfection and run with what your best engineering tells you is "good enough". That answer will sometimes be wrong and we will lose probes in the future but if we insisted on chasing zero risk we would end up with a robotic program that rarely launched anything.

[edstrick]

Something that worries me about Exo-Mars: (Without digging into the press releases and mission statistics for the REAL numbers, just working on impressions)

I get the impression the Europeans want to do a MSL class mission, with a MER mass rover, on a Pathfinder budget.

That implies an instrumentatin/hardware packing efficiency like Beagle, construction like an overstuffed Swiss watch, high costs in assembly, testing, disassembly, repair/adjustment, reassembly, retesting, etc. (like the Viking Biology Experiments, which were an engineering nightmare and astounded everybody by working almost perfectly on Mars for nearly the first and only time). And with no real rover experience, on a sub-MER budget. Correct me if I'm wrong or if they're at hand, somebody find me real numbers. I keep feeling something's running on fantasy engineering and budgeting here, like Beagle did.

[monitorlizard]

It does sometimes seem like Europe had visions of taking the lead in Mars exploration with a single ExoMars rover. But ExoMars will be a first generation Mars rover for ESA, while MSL will be a third generation rover for the US. A complex first mission isn't imposible, but it usually means massive cost overruns. Ask anyone in the Pentagon, where ambitious program cost overruns are a way of life (space projects and others). While faster-better-cheaper hasn't been officially pronounced dead, it really only works for relatively simple mission concepts.

About Skycrane, what I was thinking was that I'd like to see something like the Viking test where they took a balloon up to 100,000 feet or so and dropped a Viking component (aeroshell or something, I can't really remember). It would be nice to see a Skycrane with a dummy mass dropped from high altitude and actually firing/flying as it would at Mars. Of course, it's not practical or affordable, and would probably have to land on Mt. Everest to simulate Mars surface pressure. I do have confidence JPL will do everything resonably possible to make Skycrane work, though.

[ustrax]

I get the impression the Europeans want to do a MSL class mission, with a MER mass rover, on a Pathfinder budget.

Probably you're right...
And HOW I would widh they could find the formula for that...
There's one, certainly...
And maybe we, Europeans, wuill find it, with all the steps undone...Maybe it is time to give a step forward...
Europe has the funds and, above all, the intellingence to proceed a secure space exploration program, including MARS...
With our way of being it wouldn't surprise me to have an Euro-Russian-Chinese mission to be the first to land on Mars...It wouldn't...

[dvandorn]

That's a bit of a sweeping generalization there oDoug. Of all the failures only the MCO english/metric units problem and the commanding error that led to the loss of Phobos 1 could really be called "simple". Out of 21 failures by the various participants in the Mars race I'd say that 2 cases caused by simple mistakes hardly deserves to be described as "most".

Perhaps... though, when you look at the numbers, it seems that the majority of Mars probe failures fall into distinct categories:

Decent engineering, bad workmanship: This plagued a lot of the early Soviet Mars probes.

Launch failure: This is responsible for 40% of the American failures -- Mariners 3 and 8.

Simple mistakes: In addition to MCO and Phobos 1, I would add the failure to fully evaluate how the MPL software would react when the landing gear deployed as a "simple" mistake, making this category responsible for another 40% of American failures. Granted, this probably doesn't qualiify as "most," but it's only equaled by lauinch failures, at least for the American program. (And, hey, wasn't one of the Viking spacecraft accidentally shut down for good by a bad command load? That sort of falls in here, too...)

Plain old bad luck: I put a few failures in this category, including the Mars 6 lander, Beagle 2, the DS2 penetrators, and even Mars Observer. In any complex mechanism, you will always have mechanical failures, and these missions tended to run into them at critical points in the missions. Either that, or had the bad luck of hitting the ground at the wrong angle, or onto a badly placed rock, or onto the side of a hill, or during a global dust storm... in other words, just getting on Mr. Murphy's bad side.

So, OK, maybe "most" isn't appropriate. But you gotta admit, of the various categories, it ain't insignificant, either...

As to your other point they can and should test, test, test and then test some more where they can but at the same time we have to accept that there is a point where you have to stop chasing perfection and run with what your best engineering tells you is "good enough". That answer will sometimes be wrong and we will lose probes in the future but if we insisted on chasing zero risk we would end up with a robotic program that rarely launched anything.

I totally agree with the old engineering maxim that "Better is the mortal enemy of good enough." I just think that, in some cases, you have to raise the bar a bit in your definition of "good enough." I would say that, for example, a full simulated run of the EDL software, with all expected events represented accurately in the simulation environment, ought to be an absolute requirement for all Mars landers. The failure of this box being checked off (or even existing on the checklist, for all I know) in the MPL development cycle most likely caused its failure. It's this kind of thing -- flying the mission with a fatal flaw in its software that could have been caught with a single full-sim run of the EDL software -- that I think you just have to commit yourself to achieving, regardless of its impact on development costs.

Of course, as with anything I write here, that's just my own $.02's worth...

-the other Doug

[climber]

Of course, it's not practical or affordable, and would probably have to land on Mt. Everest to simulate Mars surface pressure.

Much much higher than that Monitorlizard! There's still 20% atmosphere pressure on top of Mt Everest... you can breeze safely.

[edstrick]

"...Mars 6 lander, Beagle 2, the DS2 penetrators, and even Mars Observer..."

It's hard to say what killed Mars 6, insufficient telemetry or they've never admitted what they concluded <correct me if I'm wrong>

Beagle, DS2 and Observer had systematic management problems and post mortem analyses indicated all had fairly serious inadequacies in testing and perhaps design. DS2 was, the report concluded, clearly not ready to fly.

You can have marginally designed spacecraft that fly perfect missions and you never know how close they came to disaster, and you can have well designed robust vehicles taken out by one 'oops', in design, manufacturing or flight.

[monitorlizard]

Much much higher than that Monitorlizard! There's still 20% atmosphere pressure on top of Mt Everest... you can breeze safely.

Of course, I meant Skycrane would have to land on Mt. Everest to simulate Mars surface pressure at the bottom of Valles Marineris on a very cold day, with carbon dioxide jets erupting.

[climber]

Of course, I meant Skycrane would have to land on Mt. Everest to simulate Mars surface pressure at the bottom of Valles Marineris on a very cold day, with carbon dioxide jets erupting.

Now I understand why you don't trust Skycrane! In a sense you're right; if you're precise enough to land on an eruptive jet, you don't even need a Skycrane

[Ant103]

I get the impression the Europeans want to do a MSL class mission, with a MER mass rover, on a Pathfinder budget.

Good I will note that!

I hear here that ESA have to make a less ambitious missions, like NASA for the rovers (Pathfinder before MER, and MER before MSL). But, can NASA communicate the testings result to ESA in the aim to win some time? Remember that the atmospheric entry of MPF wasn't testing because this mission used the same system of Viking mission.

[nprev]

Sorry if this is old news, but just noticed that an advanced life-detection instrument is under development for ExoMars by the US Scripps Oceanographic Institute. Looks promising!

http://scrippsnews.ucsd.edu/article_detail...article_num=768