NASA Rover May Contaminate Its Samples of Mars

sciencehabit writes "The Curiosity rover will definitely find evidence of an advanced civilization if it lands safely on Mars. That's because rock samples the rover drills are likely to be contaminated with bits of Teflon from the rover's machinery, NASA announced during a press teleconference. The bits of Teflon can then mix with the sample, which will be vaporized for analysis. The problem for the scientists is that Teflon is two-thirds carbon — the same element they are looking for on Mars." Fortunately, this problem isn't a showstopper: "...there are still mitigation steps to take if SAM's analysis is potentially compromised. Contaminant production appears to be stronger in the drill's percussion mode, when it pounds powerfully and rapidly on Martian rock. So ratcheting the percussion down, or switching over to the more gentle rotary mode, may make the issue more manageable. If that doesn't work, the MSL team could just take the drill out of commission, solely scooping soil instead of also boring into rock. Curiosity could still access the interior of some Martian rocks by rolling over them with its wheels, Grotzinger said. But all in all, he's confident that the team will figure things out in the next month or two."

Two-thirds carbon?

[jeffb (2.718)]

I think somebody had another English-metric goof when they were doing their stoichiometry.

(CF2)n -> 24% carbon, 76% fluorine by mass, at least by my calculations.

Re:really?

[SomePgmr]

It sounds like the teflon is from rings higher up in the assembly. It's not like they covered the bit in teflon and later did a full-on Picard facepalm.

They seem optimistic that they'll be able to work around it. I guess these lessons come with the territory when operating hugely complex projects to other friggin planets.

Re:How'd they catch it?

[afidel]

I'm sure they caught it with the duplicate here on earth. For just about every NASA mission they make at least one duplicate to be used for troubleshooting and mission prep here on terra firma.

Re:How??

[Anonymous Coward]

The Teflon is not on the drill bit; it rubs off of sealing rings in the main drill assembly. I know it's tough for you to believe, but the people who send robotic probes to other planets are, by and large, not idiots.

Re:Two-thirds carbon?

[vlm]

Actually its even worse. I'm assuming they're using a mass spectrometer and you get one C ion for every two F ions. So they got the concept of the ratio correct, but backwards. Well, its just journalism and PR, can't expect much from those folks.

Re:How'd they catch it?

[Anonymous Coward]

For this kind of thing, you typically deliver three pieces of hardware at the very least: The flight model (FM), flight spare (FS) and engineering model (EM). The FM goes on the rocket, the FS sits around in case you damage the FM before launch, and you run tests on the EM. You can keep running tests on the EM during cruise and surface operations. You might learn new things then. You certainly don't want the EM to teach you alarming new things after the FM has already launched, but it's better than having the FM surprise you later.

Re:really?

[Anonymous Coward]

did you even read TFA ?

Lab testing of a backup version of the drill uncovered the contamination problem shortly before launch of the rover and its drill last November, according to Paul Mahaffy of NASA's Goddard Space Flight Center in Greenbelt, Maryland

They launched anyway knowing the drill bit was contaminated. if thats not a facepalm i dont know what is.

Re:really?

[0123456]

They launched anyway knowing the drill bit was contaminated. if thats not a facepalm i dont know what is.

The alternative would probably have been a multi-year delay for the next launch window.

Re:Two-thirds carbon?

[Impy the Impiuos Imp]

Nobody even tried this to test it out? They didn't learn from previous missions?

I recall Voyager gathering samples, dumping it into a container, and pouring chemicals on it. Whoa! Carbon, life.

Then someone said, well, no, probably not, there were other explanations.

Why didn't someone say, "Presume the test is positive -- let's shoot holes in it." them iterate proving the test until there are no more holes they can think of.

Is that so hard before you spend billions?

Re:Two-thirds carbon?

[Urban Garlic]

> I recall Voyager...

Viking, and it wasn't looking for carbon, specifically, it was looking for long-chain hydrocarbons. Good link here [wikipedia.org].

Re:really?

[FatLittleMonkey]

The MSL uses an RTG power source. The problem with RTGs is that you can't turn them off, they start to run down as soon as they are built. MSL already missed a launch window due to delays and so was 2.5 years behind. Another delay would use up 5 years of the expected 10 years of RTG life.

Sometimes external factors force your hand.

Re:really?

[Solandri]

The multi-year delay for Galileo [wikipedia.org] following the Space Shuttle Challenger explosion is what's believed to have caused its high gain antenna to get stuck in the closed position. When you have a million parts designed to start being used in 9 months, a 2 year delay introduces all sorts of unforeseen possible modes of failure. The drill is not the only experiment aboard Curiosity. At some point, a risk assessment was made which concluded that launching it with the faulty drill was a better option than delaying the whole mission by 26 months until the next launch window and potentially jeopardizing all the other equipment aboard.