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The Viking Landers, 25 Years Later
bavid314 writes: "CNN has a decent story looking back on Viking I and Viking II. For someone who wasn't alive at the time of the landings, it provides a good synopsis. Furthermore, it evokes the question of why recent missions fail to include biological experiments to test for the presence of life."
I've always been proud of the fact that my dad worked on one of the "search for life on Mars" projects -- the GCMS project (gas chromatograph mass spectrometer, affectionately dubbed the "green-colored Martian sniffer").
Those were the days when we did big space science, before we lost some of our hope.
But boy did it make the "what my parents do" presentations more interesting for me.
Dad's retired now, but he taught me how to program (a career I likely wouldn't have if it weren't for the space program) and gave me the foundation for a good geek life.
...about using handedness of molecules to test for
biological processes - is there an error in there
somewhere? If similar biological life evolved
independently on Mars, it would prefer one or the
other handedness. A better test would be to
have a sample that initially contains both types,
in equal measure, to expose it to your sample,
and then to see if the ration had changed.
And isn't this actually an idea of Richard
Feynman's, from one of his public lectures? I'm
pretty sure I've heard it before...
K.
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-- Proud descendant of semi-nomadic cattle-herders.
If a silicon-based one was possible, Earth was the perfect planet for it.
Well, perhaps not. If carbon life is 100,000 times more likely to develop than silocon life (for reasons mentioned elsewhere sucn as silicon's weaker binding properties and lower reactiveness in simple compounds), and earth has 10,000 times more silicon than carbon, then under those conditions carbon based life is still 10 times more likely to develop than silocon based life. This by no means rules out silocon based life at all. Indeed, perhaps the presence of carbon, even in smaller amounts than silicon, was sufficient for carbon based life to evolve first, preventing any silicon life from ever developing (or outcompeting it in the primordial soup, which amounts to much the same thing).
In which case earth would not be the perfect place for silicon based life to develop, as it has been "poisoned" by the presence of carbon. This does not remotely prove, or even strongly imply, that silicon life can't and won't develop elsewhere. It merely suggests that, in earthlike conditions, carbon life is much, much more likely to develop. Even that is uncertain, as we have but one data sample, namely the Earth. The opposite could well be true: maybe silicon life is ten times more likely to develop than carbon based life, but we are one of the "ten percent" which have, nevertheless, developed carbon based life. Without additional datapoints (other worlds) the best we can do is make suppositions about this sort of thing, and any supposition we do make is necessarilly suspect.
The Future of Human Evolution: Autonomy
How do you design a test for life that is all-encompassing? Isn't it arrogant to assume that our definition of life (that which revolves around our ball of dirt) is the only definition? What about a silicon life-form? We are designing tests for carbon-based life, tests for earth life.
What kind of test could we send to detect microbial life that diesn't meet our definitive tests?
This, I believe, is the one major and convincing point to send a crew to mars. not to do the photo-op fluff piece, but a 1 week or 1 month stay trying to grow everything in petri dishes,etc...
I doubt any super simple probe test will ever product any conclusive evidence that will be accepted. On the other hand, short of bringing back a 3 eyed green martian, wont convince many in the poloticical-scientific community.
Do not look at laser with remaining good eye.
Maybe we should tell them the truth, that all the chimps we sent into space came back super-intelligent.
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NASA doctor
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"Outlook not so good." That magic 8-ball knows everything! I'll ask about Exchange Server next.
Question: When the first pictures from Viking 1 where released, what did Time chose to put on the front cover that week?
Granted they put a little teaser pic in the top-right corner with the caption Inside: Mars.
And you think there is less interest in space now?
If you don't want to repeat the past, stop living in it.
But I don't think that smaller and cheaper is worse... it obviously reduces the impact in case of a failure.
Even a small probe needs a huge rocket to launch it. Indeed a small probe may need a more expensive tracking network, since the eaiest way to cut down of weight is to make smaller solar arrays or RTGs.
Moreover, I would reason that the instruments used in modern probes are lighter, cheaper, sturdier, smaller, more powerful versions of the ones used on the big old probes.
But the old stuff is likely to be a lot more resistant to radiation. The smaller a circuit the eaiser it is for a single charged particle to mess things up.
Well, similarly, I see no reason why Mars wouldn't be teeming with life that's not carbon-based.
Problem is that no-one can come up with any kind of chemistry which can be as complex and varied as carbon based organic molecules. Also these kind of compounds are very common.
A more definite answer to that question (and a nice exercise in interstellar navigation and precision landing) could be obtained by landing a probe right next to one of the Viking probes and
a horribly compex piece of navigation. Also the only time anything like this has been done used a manned lander
seeing if some of the materials they were made of have been chewed at, or consumed, at a rate that's not explainable by natural phenomena.
Only proves anything if this has actually happened. Martion lifeforms might find a terestrial machine inedible, or take a long time to noticably consume such a large object.
That doesn't exclude other forms of silicon-based life, but chances are any life that is out there is carbon-based (though not necessarily the same as carbon-based life as we know it.)
Possibly similar compounds, but different in issues such as chirality. (Some common organic compounds have multiple chirality). Also it's perfectly possible to have amino acids, fatty acids, sugars, nucleic acid base pairs which do not exist in terestrial organisms. Let alone that you can have different "genetic codes" even with DNA/RNA chemically similar to that on Earth.
One failed because it crashed, it was landing in an area that hadn't been surveyed. Significantly, Viking DID survey the area before they landed, which is why they missed the July 4 target landing date.
One (climate observer?) failed due to a lack, apparently, of redundancy in the control systems.
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uh, wrong analogy. anaerobic lifeforms (e.g. lactic acid bacteria) were already well known to early biochemists (19th century stuff). The extremophile analogy is closer. Speaking of which: the fact that life will occur almost everywhere, I think, is further reason to doubt that the Mars Meteorite (I forgot the number) contained evidence of Martian microbes: if they were there, they should still be there and thriving and easily found, even in the Martian extremes.
My grandfather was procurement officer for the Viking I program at Langley, they had a a reuninon party which I attended. Everyone kept remarking about how everyone worked together then and how now it's a giant rat race, everyone competing against each other. It's a good point to observe, the companies are very cutthroat now adays, and don't cooperate as much as they used to. Look at the unit conversion (or lack thereof) that caused the probe to crash. Lack of cooperation. Patrik :) http://pjbutler.dhs.org/me
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Just your ordinary BOFH
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Just your ordinary BOFH
http://killertux.org
"In 1997, Biospherics' President and CEO, Dr. Gilbert V. Levin, announced his new conclusion that his 1976 Viking Labeled Release (LR) life detection experiment found living microorganisms in the soil of Mars. Objective application of the scientific process to 21 years of continued research and to new developments on Mars and Earth forced this conclusion. Of all the many hypotheses offered over the years to explain the LR Mars results, the only possibility fitting all the relevant data is that microbial life exists in the top layer of the Martian surface." Details here.
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-- SIGFPE
The fact that it didn't succeed in raising funds is in no way evidence that it was in fact a ploy to raise funds. In fact I have been complaining about NASA's exaggerations for many years now on the grounds that it's short sighted, people will eventually see through them, and thus the money will suddenly dry up due to disillusionment with the whole subject of Mars.
---- SIGFPE
Of course, it's still a massively controversial subject and they must have been hoping that it would be good for their funding. The press release was dated August 1996, which is certainly a good time for NASA to have been feeling a bit poor. In fact, looking at the 2000 NASA budget testimony, if the 1996 release was a bid for funding, it really didn't work very well.
Of course, we could always find a planet populated by robots a la Transformers....
Bill Waterson, Calvin and Hobbes. "Sometimes, I think the best evidence that there's intelligent life in the universe is that none of it has tried to contact us yet."
The only "intuitive" interface is the nipple. After that, it's all learned.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
Try getting an organic chemist to say "silicon-based life" with a straight face.
IANAOC, but the short answer is that while you can substitute silicon for carbon on paper, the properties of silicon are different enough to make this impossible in practice. For instance, the silicon equivalent of methane (CH4) is silane (SiH4) which spontaneously burns on contact with oxygen. Silicon-to-silicon bonds are weaker, so making large compounds is difficult; smaller silicon compounds (e.g. SiO2) are often stable and unreactive.
That doesn't exclude other forms of silicon-based life, but chances are any life that is out there is carbon-based (though not necessarily the same as carbon-based life as we know it.)
This is roughly the insight that led to the Gaia hypothesis.
James Lovelock came up with the idea when he was hired to do some life-detectors for Viking. His reasoning went along the lines of:
- 'Life' can be taken to refer to a property of a system that allows it to stay in a non-equilibrium chemical state. (bear with me)
- 'life' achieves this by interaction with its environment.
- This interaction therefore leaves the environment in a non-equilibrium chemical state - for instance the Earth's atmosphere wouldn't contain 20% oxygen in the presence of lots of reducing agents unless something is actively producing fresh oxygen.
- therefore a nice test for life on, e.g., Mars is to look at the chemical composition of the atmosphere and see if it's chemically stable in isolation. Which, disappointingly perhaps, it is.
The nice bit about this approach, I thought, is that it uses a sufficiently generic definition of life that it avoids the carbon-centric issue. As long as you go along with his 'life' definition.The really hairy conceptual leap from there is the full-on Gaia hypothesis which roughly says that if 'life' is defined as above, then the whole Earth might be treatable as 'life' since it's out of chemical equilibrium. Take it or leave it - Lovelock refuses to refer to Gaia as other than a Hypothesis.
Good piece or Gordian-knot cutting by Lovelock, I thought.
TomV
It's interesting how they regard the Viking probes as something gigantic and powerful(and, importantly, successful) as opposed to recent probes that are smaller and cheaper. But I don't think that smaller and cheaper is worse... it obviously reduces the impact in case of a failure. Moreover, I would reason that the instruments used in modern probes are lighter, cheaper, sturdier, smaller, more powerful versions of the ones used on the big old probes. And they made significant advances in a ton of other areas, they know more about where to look for failures, they have more powerful computers, transcievers (DSN I guess) and so on... so why is the faster/cheaper/smaller approach showing itself as a failure?
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The Vikings were great spacecraft, there's no doubt about that, and the things that they discovered about Mars have been invaluble to planetary scientists over the past 25 years. However, the biology experiments on board the landers were just poorly thought out crap.
Prior to the Viking lander touchdowns, the only spacecraft to touch down on mars was the Soviet Mars 3 mission which landed safely in 1971, only to have its computer lock up 30 seconds later such that no data was ever sent from the surface (D'oh!). All that was known about the surface was that which could be learned from orbiting spacecraft -- geomorphology, aeronomy, and the like, but certainly no chemistry. By sending generic rudimentary biology experiments to Mars without any knowledge of the chemical environment they would be operating in NASA set itself up for the rash of uninterpretable data that those experiments returned. In addition, the biology experiments for Mars were designed by astronomers, not biologists, and their focus reflects this.
This failure has an important lesson to teach us about planetary exploration: don't get ahead of yourself. Before we can go searching for life, we need to do some basic science, learning about how a planet works before blindly looking for our version of life everywhere. Despite this, every NASA Mars press release mentions how Mars Odyssey, or MGS, or whatever new spacecraft will be looking for life, and that's too bad. At least the spacecraft themselves are better thought out, sent to address specific scientific problems and to teach us more about the planet Mars so that someday we CAN go look for life, but this time, we'll do it RIGHT.
No, they're just afraid of finding out that life on Mars is more intelligent than your president. Then again, that's not too difficult.
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"Information wants to be paid"
However, there is no proof that other forms of life, such as silicon-based life, don't exist.
Try getting an organic chemist to say "silicon-based life" with a straight face. And don't give me any crap about being open-minded -- take the classes yourself and you'll see why carbon is IT, baby.
err...scientists (and wine makers) have known about anaerobic microorganisms for a long long time. the process of fermentation is caused by microorganisms gaining energy from carbohydrates without using oxygen as a terminal electron acceptor. and you don't need to go to the bottom of the atlantic to find thermophilic bacteria either...you can find them in geothermal springs, where the water temperature can be routinely as high as 95 degrees celcius.
no big surprises there...guess i've been trolled, haven't i?
No, I don't think we are going to do that.
Enigma
Enigma
Interstellar navigation? Interplanetary, surely.
A nice argument, with only one tiny flaw: all life found to date or theorized about requires liquid water, at least for a reaction medium if nothing else, and there isn't any liquid water on the Martian surface.
If you stack all papers discussing life on Mars on top of eachother, you can probably reach Mars
Non-oxygen-breathing does not equate with non-carbon-based.
Please wait until you've finished your 10th grade biology class before making this proposal.
Well, similarly, I see no reason why Mars wouldn't be teeming with life that's not carbon-based. A more definite answer to that question (and a nice exercise in interstellar navigation and precision landing) could be obtained by landing a probe right next to one of the Viking probes and seeing if some of the materials they were made of have been chewed at, or consumed, at a rate that's not explainable by natural phenomena.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I'll tell you why they stopped searching for life, they already found it. Or rather, it found us.
For the last couple of years the martians have been sending their best specimens to earth to infiltrate into our governments. Just recently they booked an enormous success. They managed to get one of their top spies into the most powerful position on earth. Sure, he still has a speech impediment and he still has trouble with human logic but it worked! The humans actually bought it!
No no.. its just that there was more national pressure back then. It was seen as real important. Thus more money, more brilliant people.. that sort of thing.
Finding conclusive proof of life on Mars would cause a huge, HUGE change in the is country and all over the world concerning the need and worth of the space program. On the other hand, having lots of fanfare and parading about that you will test for life, but then fail to find anything will cause more backlash and disgruntled Americans to wonder why we are hurling things up into space when, by all rights, we could be thinking about the children.
Probably the best solution, and I think this may have been happening all along, would be to do preliminary tests in secret, maybe by seperating a 10 part test into 10 different missions, where they would never be discovered by the press, but that could help them determine whether or not they should go balls out on another test for life.
Of course I am pulling this out of my ass, but at the same time NASA has become less of a science endeavor and more of a PR firm. They still do some science, but in order to justify it to the public, it has to be sexy.
...just my 2 cents
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Hard to believe that it's already been 25 years since Leif Erickson and his Viking pals first came to North America.
Of course, they landed way up in what is now the Canadian great white north, so it is not too surprising that no signs of life were found.
My former adviser was telling me about an experiment that's planned to fly on some future Mars probe: they're collecting DNA samples from representatively diverse lifeforms which they will tag with a fluorescent marker and bring to Mars in something like a microwell dish. Then when it gets to Mars the probe'll toss in some Martian soil (no doubt processed in some way) and see if any of the DNA hybridizes by measuring the fluorescence.
Obviously this won't find any really weird organisms like something silicon-based (which is at least theoretically possible, see Genetic Takeover and the Mineral Origins of Life by A. G. Cairns-Smith) but it could confirm the panspermia hypothesis (Mars->Earth or Earth->Mars); and even if there was no direct relationship between Earth and Mars life, there would be some level of hybridization as long as Martian life used DNA (or a closely related analogue).
So although the bulk of the focus now is on looking for more general life-conducive factors like liquid water, past atmospheric composition, and temperature history, there's also some attention to specific tests for life, even if they are expected to fail.
Look at all the Mars stuff happening - Mars in the Media, and the immediately recent Mars opposition and new hubble shots, the killer success of the surveyor mission, the probes heading there right now, the rover mission and others.
NASA should be pimping the hell out of it. The existence of extraterrestrial life, even microbes, is a question of enormous magnitude. It is truly a question of biblical proportions. NASA's work on Mars could perhaps unravel one of the greatest mystery humans face. It will be very interesting to discover what is returned to Earth in the Mars soil samples returning to Earth in 2005. You can check out the strategy paper NASA issued on researching Mars exobiology.
The ultimate mystery!
Isn't the best evidence that there is intelligent life out there the fact that it hasn't contacted us? :)
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The US government is afraid of finding out that life on Mars is more intelligent than life on Earth.
Phoenix
I am me. Insightful, isn't it?