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Life on Mars? Why Not?
Guillaume Filion writes "IEEE spectrum has an interesting article about a new probe sent to Mars searching for life: 'Recent missions to Mars have focused on the search for water, past or present, as a surrogate for life itself. But now a British-led team is working to renew the search for life directly, fueled by doubts about the equipment that prompted NASA to declare Mars a dead world some 26 years ago.'"
Mars: Dead or Alive?
A miniaturized marvel of engineering aspires to rewrite the textbooks about life on the Red Planet
By Barry E. DiGregorio
Recent missions to Mars have focused on the search for water, past or present, as a surrogate for life itself. But now a British-led team is working to renew the search for life directly, fueled by doubts about the equipment that prompted NASA to declare Mars a dead world some 26 years ago.
If all goes according to plan, a Soyuz-Fregat booster rocket will lift off from Baikonur cosmodrome next month carrying an extremely compact and sophisticated life detection probe that might finally settle one of the most intriguing questions in science: did Mars once harbor microbial life-and is it still there?
The probe is hitching a ride on the European Space Agency's (ESA's) Mars Express orbiter as part of the agency's first home- grown mission to the Red Planet. Named Beagle 2[see photos], in honor of the HMS Beagle in which Charles Darwin made the historic voyage of discovery that led him to the theory of evolution, it was designed by scientists from Britain's University of Leicester and Open University in collaboration with Martin-Baker Aircraft and Matra Marconi Space Systems. Once the orbiter reaches Mars, Beagle 2 will be sent down to dig around on the planet's surface.
But even after it has dropped off its passenger, the Mars Express orbiter will not be idle. It will use a sounding radar called Marsis to search below the surface for water. It will have an ultraviolet and infrared spectrometer called Spicam to study the atmosphere over the course of a Martian year. And it will relay data transmitted from the lander back to Earth.
Did Viking get it wrong?
The first spacecraft with dedicated equipment to look for life on Mars were NASA's twin Viking landers, which touched down on the surface in 1976. Why send another now?
On board both Viking landers were miniature life detection laboratories, and some of the data they returned could indeed be interpreted as evidence for life on Mars. Yet the majority of the project's scientists became convinced that inorganic oxidants in the soil were responsible for the ambiguous data. The next year, NASA publicly announced its conclusion: that Viking had found no life.
Was the U.S. agency jumping to conclusions? In recent years, questions have been raised about the effectiveness of a key instrument-a combined gas chromatograph and mass spectrometer (GCMS)-that swayed most of the Viking scientists into the no-life camp. The GCMS failed to detect any organic molecules on the Martian surface at all, which posed something of a puzzle, as even the barren surface of the moon is host to some organic molecules. To explain the anomaly, scientists postulated a harsh chemical environment that supposedly made the planet self-sterilizing by actively destroying organic matter [see "Why NASA Said No to Life on Mars"].
To find out if this picture is correct, Beagle 2 is designed to search for organic material below, as well as on, the surface of Mars. In addition, it will study the inorganic chemistry and mineralogy of the landing site, says Mark Sims, the Beagle 2 mission manager who is based at Leicester University.
Without question, the Beagle 2 lander manifests an enormous leap of scientific engineering. It costs only US $40 million versus Viking's $1 billion, and weighs in at a mere 60 kg at launch, as opposed to 661 kg for each fully fueled Viking lander. In its set of scientific instruments are the first ever optical microscope to fly to Mars, as well as a gas analysis package (GAP) that will directly challenge or confirm the results of Viking's gas chromatograph-mass spectrometer (GCMS).
Beagle 2's destination on Mars is a region known as Isidis Planitia [see map]. This relatively flat basin may have been formed by sedimentary deposits and was chosen not just for the chances of finding life there but with a view to the safety of the lander as well.
...were known to be flawed, before the rockets were ever launched. Many of the tests that would have been conclusive (such as those produced by Dr Carl Sagan) were abandoned, due to budget constraints, political concerns (finding life would have made it much harder for Congress to keep slashing NASA's budget) and the greater need to impress the mass media than the scientific community.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
First off, I had heard about some of the semi-positive results of some of the Nasa experiments that were ignored, don't have a reference.
But I remember a letter sent my some professional gadfly comic...I want to say Joe Bob Briggs but I don't think that's it...who wrote to NASA saying something along the lines of "So you burnt up this soil sample to check for signs of life on Mars? That could only prove that there WAS life on Mars...you just killed it!"
(Sorry for the lack of references, the book I got that from is at home)
SO YOU'RE GOING TO DIE: The Comic for Dealing with Death
I read a book by Stuart Kauffman (hope I spelt that right). He said he was asked by NASA to help design probes to send to Mars to look for life. He told them not to bother, and his reasoning was:
All life takes in energy and matter from the environment, extracts energy, and produces waste. This process causes chemical imbalences in the atmosphere. Therefore to test for the presence of life, you only need to determine whether the atmosphere is in chemical equilibrium. Mars' atmosphere is, and has been for many millions of years.
Apparently this line of reasoning upset NASA, because they wanted to go to Mars, so they made their probes without his help, and when they arrived on Mars, found no traces of current life.
If they send more probes, they could very well find evidence of past life, but there is nothing going on there at the moment.
However I remember reading a story a while ago on Slashdot about how the atmosphere of Venus is operating far from chemical equilibrium, and that there may be some primitive life in the 400 degree acid in the atmosphere. Maybe someone should pay more attention to Venus...
- Water is highly polar, and therefore has the ability to dissolve ions. Without ions, complex chemistry could not take place.
- Water is liquid at a "reasonable" temperature, meaning water in liquid form is not hot enough to destroy most complex molecules.
- The density of ice is slightly less than that of water, so ice floats on top of water. This is vital, because it allows bodies of water to form a frozen cover which protects against further freezing. This is not common among substances.
- Water blocks ultraviolet light, which would otherwise destroy fragile molecules and organisms.
- Water has a very high specific heat, making it ideal for carrying out chemical reactions -- exothermic reactions can dump their heat into the water, and endothermic reactions can draw their heat from the water. This allows energetic reactions to occur without raising the temperature too high.
Basically, water is a very unusual substance with many favorable properties, and it's likely that life will take advantage of water, if it is present.That's not to say that life cannot exist without water, but it certainly makes life much more plausible.
As for non-carbon-based lifeforms, people have been pondering that for decades. Carbon is interesting because it can bond with itself pretty much ad infinitum, forming complicated structures. It also combines readily with oxygen, nitrogen, hydrogen, sulfur, the halogens, and a host of other elements. Complex life based on some non-carbon element would have to have the ability to form long chains of atoms, branching structures, and structured which curl up into specific shapes (i.e. proteins and enzymes). A carbon-silicon combo might work.
Could we for once view science as the continuous stretch of micro-advances that it really is?
I thought Kuhn put that silly idea to rest awhile ago?
You do realize that they aren't talking about little green men right? They are talking about microscopic organisims, and to the best of our scientific knowledge there's alot of variation possible, but it's all largly the same. In fact if it's as "different" as you are suggesting it will probably be different enough that neither NASA's or the ESA's probes would ahve the equipment to detect it. They are depending on "life" there haveing the same building block as "life" here. :)
How about a BBC article
The fungi that did the damage, Novikova said, included members of the genera Aspergillus, Penicillium, and Cladesporium - all very common on Earth.
Davak
On the one hand, I agree with you totally. The earliest life on earth was not photosynthetic; even if Martian life is photosynthetic, there is no reason to expect that it would use chlorophyll to capture photons (carotenoids, for example, also work; any aromatic compound of about the same size could do in a pinch.)
On the other hand, your nomenclature is a bit confused.
Viruses are neither cells nor creatures. Furthermore, although they are not complex, they require fairly complex hosts in order to thrive. Martian cellular life might have useless or parasitic DNA, but I rate it unlikely that this DNA kills the hosts (which must be rare,) or packages itself into particles in order to spread. In any case, the viruses would have to be more difficult to detect than their hosts.
Amoeba are not simple, either. They are single celled, but they can sense and react to their environment in amazingly complex ways - early life almost certainly could not. They are, in fact, among the most complicated single-celled lifeforms on this planet.
Modern bacteria are turning out to have complex features, such as the ability to communicate with one another, which we had not suspected.
Nevertheless, ancient bacteria, or proto-bacteria, very ancient life on earth; things similar to that might be found on Mars.
Depending on how old you think such life or proto-life is (estimates vary from 2.5 to 5 billion years) it is conceivable that some sort of nasty event could have deposited some on another planet or vice versa - but I think this is highly unlikely, to say the least.
So, what should we be looking for? Nucleic acids, particularly RNA.
This is based on the RNA-world hypothesis. Basically, it says that before modern life evolved, which is characterised by the fundamental theorem of molecular biology:
DNA makes RNA makes Protein
There was life that used only RNA. In this life, or proto-life, RNA served as both the store of genetic information (we use DNA for this) and as the catalytic workhorse of life (we use Protein for this). RNA has unique chemistry which may make it the only chemical, in the universe, capable of originating life - RNA can catalyze it's own synthesis, so it can reproduce all by itself.
So, this Martian life is probably descendended from RNA molecules, like we are, and probably still contains RNA, just like we do.
On the other hand, this argument is premised on the concept that any life we find must have a chemical origin similar to our own. Unfortunately, I think this is probably the case (so no aliens made of Quartz, sorry,) but maybe not. If it ISN'T the case, we have NO IDEA what to look for, so back to square one.
If RNA is the sole origin of life, then, basically, you need water to have life (RNA only has these desirable properties when dissolved in water.) This leads us back to the rather pedestrian xenobiology of trying to find evidence of liquid water in Mars' past.
On a final note, I think Io is probably a better bet to find extra-terran life. There is definitely liquid water, and it is rich in complex organic molecules (including RNA, I believe) it has a temperature comparable to that of the early earth, and it has rich sources of the sulfur and nitrogen compounds that early life probably used as food.
This raises a significant risk, however. There are living organisms on earth that could probably survive being transplanted to Io (the same is not true, by the way, of Mars.) So, we'd have to be extremely careful not to contaminate the place.
The good and new comes from no quarter where it is looked for, and is always something different from what is expected.
Kuhn actually said that most scientists, most of the time, are engaged in what he dismissively refered to as "puzzle solving". So even according to Kuhn, most science involves gradual progress in solving relatively small problems. Every now and again this gradual progress is punctuated by revolutionary "paradigm shifts". Kuhn was much more interested in, and wrote much more about, these revolutionary jumps. Unfortunately this has led many of his readers to mistakenly conclude that science is all about such jumps, when in fact (as Kuhn himself correctly observed) they are the exception rather than the norm.
Critics of Kuhn have also pointed out that if he had paid more attention to the 99% of science that he called "puzzle-solving" then he might have seen that the episodes of "revolution" involved more continuity with prior scientific thinking than he realized.
The NASA findings with the Viking missions were that there was no evidence for life on Mars. That doesn't mean that there wasn't any life, it just means they had no evidence for any. Big difference. NASA never stated unequivocally, "There is no life on Mars."