It’s been a bit of a heart-in-the-mouth week for space nerds around the world. On the downside, rich guy Elon Musk has failed in his third try to put a little rocket into orbit – though he’s still commendably optimistic about subsequent attempts.
But, on the upside, there were all manner of exciting rumours about what the Phoenix Mars Lander found, digging around near the Martian north pole. The story started with a report in Aviation Week that the White House was being briefed about a “provocative” discovery about Martian soil chemistry by the lander. Nerds around the world went into overdrive speculating about what that provocative discovery might be.
The fuss centers around data from the lander’s Microscopy, electrochemistry, and conductivity analyser – MECA for short. The MECA lab is designed to analyse scoops of Martian soil, collected by the lander’s arm. As well as an optical microscope, the lab dissolves a small amount of soil in water, putting it over some sensors which can detect various different types of chemicals. While MECA wasn’t designed to detect life, there are certain chemicals that MECA could find that would strongly indicate the presence of life at some time – for instance, various compounds containing nitrogen or sulphur. Microbe pooh, in other words.
The exciting news turned out to be something else entirely – the Phoenix team has results indicating the presence of perchlorate in the soil. Perchlorates are a type of chemical called an oxidising agent – that is, they readily and rapidly release oxygen in chemical reactions. This property is used in mixtures to make fireworks, trigger airbags, and in tiny quantities as treatments for hyperthyroidism. But in large quantities it’s apparently not the kind of thing that you’d find in close company with life, past or present.
In any case, the Martian polar surface isn’t exactly the place you’d go looking for life. Even during the Martian summer, it’s as cold as winter in the Antarctic, as this weather data from the Phoenix mission shows. As well as those nasty perchlorates, there’s no ozone layer on Mars; any bacteria on the surface are going to get very, very nasty sunburn. If there are microbes – or microbe fossils – hiding on Mars, they are going to be hiding below the Martian surface somewhere, probably deep in the soil.
But beginning that search in earnest – even more, to rule out the possibility of past or present life on Mars – will require a comprehensive survey of the Martian soil, across a planet with a similar exposed land area to the Earth itself. Now all we need is a few tens of billions of dollars a year to fund it…
UPDATE: Apparently, I’ve been a bit too pessimistic on the effects on any hypothetical life of perchlorates in the Martian soil (or regolith, to use the technical term). According to this informative NYT article, some terrestrial bacteria get along with perchlorates just fine. Some even eat them…
It’s been pretty frustrating for this guy, too, I see.
(“D’oh!” … “D’oh!” … “D’oh!” … “D’oh!” …)
A.A. Milne would be appalled.
I’d wondered why all the news headlines about Mars just suddenly went away. Thanks for keeping me up to date.
On the optimistic side, perchlorates=strong oxidiser, hydrogen (from water)=strong reducer. So its a basis for great rocket fuel. If we ever do want to send humans to Mars, we’ll probably need to manufacture fuel there for the return journey.
DD: I doubt the stuff would be nearly consistent enough to make a reliable rocket propellant.
Besides, if you want oxidizer, oxygen isn’t a bad one, and if you’re electrolyzing water to get hydrogen you also get oxygen…
Has this stuff poisoned the Martian soil? Os there no life on Mars, after all?
Paul: it may have poisoned this tiny sample of Martian soil, at this one specific location. Beyond that, who knows?
Drawing conclusions on whether there is life on Mars on the basis of one polar soil sample would be like wandering to a random point on the Antarctic ice shelf, taking a photo that didn’t show any macroscopic life, and concluding that there was no life on Earth.
What’s more, I think it a little Terracentric that we keep saying water, along with this or that particular compound, are “essential for life”.
Is there no possible way life could evolve elsewhere that’s *gasp* different to life on Earth?
FDB: that’s a reasonable question, but:
a) while it might be different in the details, it’s very, very hard to envisage lifeforms based on anything other than carbon-based chemistry. No other element forms the basis of such complex chemical structures. Given that, it does tend to place limits on the physical conditions for life to those in which that kind of chemistry can work.
b) It’s also pretty hard to see how that chemistry could function without some kind of liquid medium, and water is pretty much the only plausible one – most other naturally-occurring liquids at the temperatures and pressures required for life would destroy pretty much any carbon chain-based chemistry, as I understand it.
Look, you can’t rule something really funky and strange out, but if you’re looking for a needle in multiple haystacks, you go looking at the ones where the metal detector bleeps first.
Yeah, I kinda have my head around the biological arguments for carbon-based, water-needing life. The absolutism really bothers me though Especially comsidering we only know for absolutely certain about the existence or otherwise of life on ONE planet. That’s not a huge sample size, however plausible-sounding your arguments!
That is to say, a very small sample for generating conclusions about possible extraterrestrial forms of life.
That some people manage to maintain positive disbelief in their very existence beggars belief.
Sorry, I hope that didn’t come across as too patronizing.
I agree that ruling out the possibility of some other, radically different form of life is not a good idea. The universe is a big place; who knows what’s out there?
Oh, no offence taken Robert.