NASA May Have Discovered and Then Destroyed Organics on Mars in 1976 (space.com)

An anonymous reader shares a report: Over 40 years ago, a NASA mission may have accidentally destroyed what would have been the first discovery of organic molecules on Mars, according to a report from New Scientist. Recently, NASA caused quite a commotion when it announced that its Curiosity rover discovered organic molecules -- which make up life as we know it -- on Mars. This followed the first confirmation of organic molecules on Mars in 2014. But because small, carbon-rich meteorites so frequently pelt the Red Planet, scientists have suspected for decades that organics exist on Mars.

But researchers were stunned in 1976, when NASA sent two Viking landers to Mars to search for organics for the first time and found absolutely none. Scientists didn't know what to make of the Viking findings -- how could there be no organics on Mars? "It was just completely unexpected and inconsistent with what we knew," Chris McKay, a planetary scientist at NASA's Ames Research Center, told New Scientist.

Comments

Re: Please mention how the organics were destroyed

[Anonymous Coward]

The viking's spectrometer had to heat the soil. We more recently discovered perchlorate in the mars soil. Its speculated the heat ignited the perchlorate and burned away the organic material. Viking did find chlorobenzene in the soil, which would support that theory, but is not conclusive.

Re:Please mention how the organics were destroyed

[burningcpu]

Chemist here.

The author of the article is clearly a journalism major...

OK, NASA wanted to know whether 'life' was present on Mars. How do we test for 'life?' Well, their approach was to look for stuff that looks like what life on Earth looks like. Mostly, carbon containing, large molecules. Amino acids maybe.

To test for these compounds, they sent a GC/MS, which is a gas chromatograph attached to a mass spectrum analyzer. The GC/MS does a few things -- the chromatography column separates compounds based primarily on boiling point (sort of), and the quadropole (mass analyzer) determines the mass to charge ratio of the charged species, separated by the GC.

Well, not all compounds can 'fly' in a GC. Many 'blow apart' / fragment to such an extent that the 'molecular ion' / parent species is not detected, but rather, only reaction products.

That is sort of what is being proposed here. In order to analyze only the 'volatile' portions of the soil, the soil was slowly heated and the gas that evolved were measured via the GC/MS. This is a standard approach. However, one must always consider a deeper view of the data, and that includes knowing the sample, and what other interferences may be present.

In this case, perchlorate, an acid, was already present in the samples. Perchlorate is a voracious digestor of carbon containing (highly saturated) bonds. The process of heating up the sample would likely have caused a reaction between any large 'organics' in the sample, and the perchlorate that was already present. In which case, reaction products of the perchlorate and 'organics' would be detected - and according to this article - one such product was detected.

However, this small molecule, chlorobenzene, may have come from the manufacturing process of the rover and would not have been a noteworthy detection, had it not possibly indicated perchlorate digestion.

People feel real good about GC/MS data because of the MS...but they forget the sample introduction part.

Garbage in, garbage out. Like everything.

You can try it at home

[raymorris]

At 2300 degrees, steel becomes liquid. At 1500 degrees, structural steel is about the consistency (and strength) of plastic. You can try it yourself. You can get a 1/4 steel rod and propane torch at home depot. Get it the steel glowing bright red (1500) and you'll find you can easily bend it with finger pressure.

https://youtu.be/FzF1KySHmUA