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Rover Exiting Crater To Continue Martian Marathon
Riding with Robots writes "The robotic geologist Opportunity has nearly reached the rim of Victoria Crater, which it is leaving after a year of exploration inside. Rover handlers decided to abandon attempts to approach the crater's cliff walls when they saw a power spike similar to the one that preceded a broken wheel on its twin, Spirit. Opportunity is already making do with a stuck robotic arm. The mission's manager said, 'Both rovers show signs of aging, but they are both still capable of exciting exploration and scientific discovery.' Opportunity is set to continue trekking across the Meridiani Plains of Mars, even though its wheels have already seen 10 times the use they were designed for. Meanwhile, Spirit has survived yet another harsh Martian winter to produce another striking panorama."
Adam Korbitz notes other Mars-related news that funding has been approved for the Search for Extra-Terrestrial Genomes (SETG) Project. The project was one of 15 selected to receive funds through a NASA research opportunity program. The stated goal of the proposal is to "develop a PCR detector for in situ analysis on other planets, most immediately, Mars. This instrument is so sensitive it should allow the detection very low levels of microbial life on Mars, and will determine its phylogenetic position by analysis of the DNA sequence of the genes detected in situ."
PCR requires 2 primers of known sequence, roughly 20 bases long, between 100 and 1000 base pairs apart. Given that we have absolutely no sequence information from which to design these primers, how do they expect to do PCR on completely unknown DNA?
Give me Classic Slashdot or give me death!
Using the DNA samples from Area 51 that we obtained from the Martians that crash landed in Roswell, of course. Duh.
so.. we all know what would happen if Microsoft designed a motor car, but what would happen if the Rover Team designed one?
(I don't know about you, but I think still working after 4 years is damn impressive)
Does someone have a link to a medium-res copy? The thumbnail is tantalizing, but I don't want to download a 42MB TIFF.
Are there any key lessons to be learned from these rovers' success? Or is it simply that they have no critical consumables (being solar powered and all) and they evidently were overengineered? I guess for starters, having redundancy and the ability to turn off failing components is good, seeing as they're six wheel drive and one of the rovers is now dragging a bad wheel around. What else has been learned from these rovers about engineering long-lasting probes?
Or that Optimus Prime hasn't stomped on it.
Utilizing the synergization of benchmark e-solutions to pre-workaround action items!
Because the SETG team's directions to lab/shipping info is only available in pdf format.
Why look for martians? If we find one, they're just going to be turned into a celebrity and buy a small poodle and say, "That's hot" to everything... wait a second! Is Paris a.... nevermind, can't be, she's way too dumb, and definitely not a good actress.
Anything and Everything about the Net
those precious little life forms...
Those tiny little life forms... o/~
Where are you... o/~
With spending like this, exactly what are "conservatives" conserving?
WTF? I think we should first concentrate on finding something that somewhat resembles our microbial life before we spend a lot of government funds to ship a PCR detector there.
Not only do they assume that life there has genes in about the same way as ours but also that they are made from the same nucleotides. What would be the odds of that? (excluding panspermia and so on).
As long as there are slaughterhouses, there will be battlefields.
"...the Search for Extra-Terrestrial Genomes (SETG) Project..." Sigh. I read that as "the Search for Extra-Terrestrial Gnomes Project". It's late. I'm tired. Perhaps I should stop coding now...
It's much worse than that. What makes them (or you) think that alien life will have any DNA at all?
They seem to be assuming that alien life will share a common ancestor with Terran life. This seems like a pretty dubious assumption to me.
The most rabid believers in American Exceptionalism are the exact same people whose policies are destroying it.
You can get around the need for primers by fracturing the DNA using restriction enzymes or mechanical sheering to break the unknown DNA into shorter fragments and then ligating adaptors onto the ends of your new 100-1000 bp fragments. Then you use primers complementary to your adaptors and viola you're in business.
My question is why we'd expect life on Mars to use DNA at all.
I can just see Luke coming up over that ridge in the speeder... too bad for the whole 'no oxygen' thing.
stuff |
16S RNA gene PCR, the most sensitive detector for life on Earth
This detector is an amplification strategy called the Polymerase Chain Reaction (PCR) that is based on artificial replication of DNA. PCR is a technique which is used to amplify the number of copies of a specific region of DNA, in order to produce enough DNA to be further analyzed. In order to use PCR, one must know the exact DNA sequences which lie on either side of a given region of interest in DNA. One need not know the DNA sequence in-between. A DNA sequence is the precise order of appearance of 4 different deoxyribonucleotides. The 4 components are: Adenine, Thymidine, Cytosine and Guanine, abbreviated A, T, C and G, respectively. The arrangement of this 4-letter alphabet is the DNA sequence.
The PCR strategy for life detection emerged from the exploration of the diversity of life, which revealed about 500 Ã'universal genesÃ" that are carried in the DNA of every known living thing on Earth (7). The gene that has changed the least over the past 3-4 billion years is the 16S (or the related eukaryotic 18S) ribosomal RNA gene. Ribosomal RNAs are the main structural and catalytic components of the ribosome, a molecular machine that translates RNA into proteins (8,9).
It is the slow rate of change of the 16S gene that makes it the best detector of life. Within the ~1500 nucleotides of the 16S gene, there are multiple 15 to 20 nucleotide segments that are exactly the same in all known organisms (8). These regions of the 16S gene are essential for its catalytic activity and have remained unchanged over billions of years (8).
The technology of PCR involves adding stable 15-20 nucleotide long DNA primers, a stable enzyme nucleotide triphosphate monomers, and a simple heat pump that thermally cycles 20-30 times in 2 hours. To amplify 16S genes from a crude sample, universal DNA primers from the ribosomal RNA gene that are about 18 bases long, oriented towards each other, and about 1000 bases apart are added to crudely purified DNA isolated from an environmental sample (for example, 1 ml of sea water or 1 gram of earth). For the ribosomal genes, the DNA primer 5Ã GTGCCAGCAGCCGCGGTAA 3Ã which corresponds to nucleotides 515 to 533 of a ribosomal gene, and 3Ã TTCAGCATTGTTCCAWYGGCAT 5' which corresponds to the base pairing complement of nucleotides 1492 to 1510 are added to an extract prepared from soil (M, Y, and W are codes for mixtures of two such nucleotides necessary to capture all 16S genes). Upon heating to 95ÂC and then cooling to 55ÂC, these DNA primers pair with their complement on each DNA strand, even if there are only a few DNA molecules in a sample. After heating to 75ÂC, the DNA polymerase will polymerize the nucleotide monomer components also in the tube to duplicate the DNA strands. There will now be four strands, where originally there were only two. If one repeats the thermal cycle with all the same components in the same tube, now there will be eight strands; repeat again - now 16, etc. Thirty cycles will produce one billion (230) copies of the original sequences. Because the DNA polymerase enzyme used derives from a thermophilic microbe, it can survive repeated cycles of heating to 95ÂC. The amplified DNAs from the PCR can be analysed for size or DNA sequence. PCR will even amplify complex mixtures of 16S ribosomal RNA genes from communities of organisms in environmental samples. Thus, PCR with DNA primers corresponding to the conserved elements can be used to amplify DNA from any species more than a billion fold, without need to isolate, culture, or grow the organism in any way (9).
Because they have to start somewhere? It isn't unreasonable to think that most naturally occurring forms of life are based on DNA. Yes, that is an assumption that could be wrong. We have one data point to work from. If our assumption is wrong, we can create different methods of detection other types of life.
My question to you: what kind of machine would you put together that would search for microscopic life forms that are of a type we have yet to imagine? When you answer this, then you can mock the article's approach.
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I read "Rove Exiting Crater To Continue Martian Marathon".
Can John McCain be shipped to Mars? Apparently he has recently diagnosed Alzheimer's Disease.
Thanks.
I wish NASA would get off the "looking for ET life" kick. The probability of finding any sort of life on Mars is vanishingly small. I suspect that NASA knows this, but thinks that it can capture the public's imagination (and thus pocketbook) by pushing the whole "Searching For Life" thing. There are so many other experiments we could do that have a much higher payoff.
I don't think the search for life is going to fire the public's imagination more than the cool photographs they get back. If they *really* want to get the public excited, send an HDTV recorder up there to zoom around... maybe even stereo HDTV so we could see 3D. Let me see a Martian sunset. Those are tactile things that everyone can be excited about. The search for life is an endless string of boring failures. Sure, if it *did* succeed, it would be immensely exciting, but that's like saying it would be exciting to win the lottery, instead of paying the rent. Except winning the lottery is a lot more probable.
Sometimes it's best to just let stupid people be stupid.
I think that's a ludicrous assumption. A reasonably safe assumption is that most life in the Universe is carbon-based, simply because carbon is capable of making the largest and most complex molecules. There's no reason I can think of to think that the end result of any abiogenesis process has to be DNA as the replicating molecule. Carbon can probably be used to produce all sorts of replicating molecules.
The world's burning. Moped Jesus spotted on I50. Details at 11.
They would use random primers. A DNA hexamer (six-base sequence) is sufficiently long to serve as a PCR primer, but short enough that it would take only 4096 different types of molecule to comprise all possible sequences. Of course, we don't want the sample DNA to be plastered in our primers, so we'll pare those 4096 down to a handful, at least one of which, in any sample sequence of significant length, will nonetheless find somewhere to anneal. Once we've gone through enough cycles, it's likely that we'll have amplified at least some segment of the sample DNA. Then, getting the reaction contents purified and sequenced is simply a matter of applied microfluidics.
But without all the poverty.
- Zav - Imagine a Beowulf cluster of insensitive clods...
Use random primers, just like you do for reverse transcription when you want to pick up all the RNA sequences in your sample. The reaction's efficiency would take a hit, but if all they want to do is detect DNA (or maybe even sequence a few very short sections) it could probably be made to work.
A bigger problem is the enzyme used in the PCR. IANABiochemist, but I'd expect the PCR to only work if the Martian bugs hava genomes based on double-stranded DNA chemically very similar to ours.
There are plenty of stable nucleotides that could work as components of DNA but, for some reason, aren't used in Earth's life. Ditto chirality: Using the same constituent atoms, one can build almost identical but left- or right-"handed" versions of molecules. For some reason -- probably just chance -- Earth's life is based on "lefthanded" molecules, meaning that we can't produce or consume right-handed molecules. For example, if we synthesise right-handed sugars (easy for a chemist to do, but expensive), they have the same chemical composition, melting point etc, but the structure is such that our enzymes can't use it as a source of energy. Heck, even the sequence of any DNA scooped into the chamber will be important, as if influences the reaction conditions you need for the PCR to work.
If there is life on Mars, this test would only be able to detect it if Martian life is spookily similar to our own. Which would, I'll admit, be even more exciting than just "life on Mars" because it would hint toward evidence of Panspermia or possibly some sort of fundamental rules about what life is able to look like.
I noticed that you did not answer the second part of my post. What kind of process WOULD you use to detect these Non-DNA based life forms?
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Simply STFW (skimming the fine webpage?) one notes a phrase "did life catch a ride?"
That phrase implies that they're not looking for "super freaky unique and un-predictable alien genetic matter" so much as "something similar to earth dna," which renders the "what are they going to use for a base?!?!?!!" question irrelevant.
A microscope.
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Yes and no. I think it is entirely more likely that life inside our solar system shared a common past at some point, than it is for life to just so happened to form completely independent of one another.
If life happened to form in two different places, independently, within our solar system, either we hit the cosmic jackpot, or life is much easier to form than we ever thought possible. And if that is the case, then through the vast amounts of universe that there is, we would have seen SOMETHING SOMEWHERE from a more intelligent race. After all, we can't be the only beings that would be sending/looking for extraterrestrial signals, could we?
It just seems to me, that it is more probable that if life isn't plentiful and easy to form, that finding life somewhere else in our own back yard means that we came from the same origin.
"When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
At first, I thought this was snarky (and it may very well have been meant that way). However, if you could send the probe with a microscope, and a method for having the visual sent back to Earth for a team of analysts, this might not be a horrible idea.
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We don't know how life arose on Earth but the assembly of complex self-reproducers from simpler compounds doesn't seem like any everyday occurrence. We do know that material can be transferred from Mars to Earth and possibly vice versa. So if we find life on Mars we have three scenarios:
A simple application of Bayes' theorem tells us that the first is the least likely.
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
Presumably the grant is for a few tens of thousands of dollars (I looked a bit but did not find an amount); if that is correct,(in my opinion) it is quite okay that it is based on a ludicrous assumption (because it might increase their ability to detect dna from 'negligible' to 'maybe').
Nerd rage is the funniest rage.
Where i can buy the technology used on Spirit? I will like a device with capacity to work ten times the estimated working life (but will be the terror of companys, off course. A TV don't exploding on one year of use? wooo!)
Religion: The greatest weapon of mass destruction of all time
Anyone noticed the absence of round features?
that got there aboard Viking, Mariner, etc. The terraforming has already begun.
I liked the idea that got struck from the Viking mission. Put out a petri dish with some yummy organics, and drop some martian dust on it. See if anything grows.
IANAChemist, but seems like there should be some way to detect interesting organics other then a DNA test...
There are any number of much better ways, ranging from the "wolf trap" to microscopes. I would think that at least finding evidence of complex carbon based molecules would take precedence over trying to run PCR on hypothetical DNA (in truth, NASA would likely want that evidence before sending this device). That said, Mars is actually the only planet where this has a chance of working, given the number of possibly life bearing meteorites that have surely passed between there and here.
There are exactly 8 bio-suited information storage molecules.
L-sDNA
L-sRNA
L-dDNA
L-dRNA
R-sDNA
R-sRNA
R-dDNA
R-dRNA
Cellular life uses R-dDNA for data storage and R-sRNA for data transport. All R- variants are used by at least one kind of virus. As dDNA is the most stable storage medium most life on Mars should be using it.
The only thing that is liable to be missed is the chance that it uses L-dDNA, which would be a facinating discovery (independent origin).
Even developing a space-ready PCR system seems premature at this point. What about looking whether there is DNA there in the first place?
the problem is which is which. It should be obvious they are making the assumption that life that we are interested in has DNA. After all, we know about prions (not life, but certainly infective). But unless we have a FULL chemical lab there, we will not know what to look for. So the safest (and easiest) solution is to assume that life has some common grounds. What I am going to be curious about, is that it is possible for DNA/RNA to have different base pairs. This will ahve to assume the bases that we know. So, it is also possible that we will miss life unless it had a common heritage with us.
BTW, this does show something interesting. In the end, our lack of ability to detect life unless it is similar to ours shows that our first explorers will need to be on a one way trip. At the very least, they will need to be with out earth contact for at least 10 years if not longer. Do we really want to risk bringing back something "new and interesting"?
I prefer the "u" in honour as it seems to be missing these days.
>the assembly of complex self-reproducers from simpler compounds doesn't seem like any everyday occurrence.
The evidence seems to show that the appearance of cellular life occurred quickly after the Earth developed a stable surface cool enough for widespread liquid water. That would argue that "life arising spontaneously" is not particularly unlikely. That might change which variable you assign as A and B in Bayes' Theorem.
Some mornings it's hardly worth chewing through the restraints to get out of bed.
To paraphrase the article: there is a sequence of nucleotides common to all terrestrial organisms with known end sequences (possibly multiple alleles thereof) and hence known PCR primers. If PCR succeeds that would tell us that DNA of common ancestry was present. Subsequent analysis would tell us the sequence and hence when the organism diverged from terrestrial common ancestor.
The article also addresses contamination and engineering issues.
The article is a slow and difficult read if you don't know PCR in detail but I thought I'd paraphrase as best I can since, while I'm not a molecular biologist, I've spent the last year writing SSO analysis software... As always, wikipedia is your friend.
Fifty-fifty sort of thing. Didn't some dudes recently make a microscope the size of a dime? I just think we've got better odds dropping microscopes from space and looking to see if they land on marscrobes than we do trying to genetype the damn things. GATTAQA?
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Kind of like the microscope on Phoenix? http://www.nasa.gov/mission_pages/phoenix/news/phoenix-20080814.html
100nm resolution. DNA however is only 3nm wide.
Or even:
4. Life arises somewhere else, and is transported to Earth and Mars by a known mechanism
My blog. Good stuff (when I remember to update it). Read it.
If life is commonplace, there are probably at least some chemical commonalities (carbon, for example). It may be that the formation of DNA or DNA-like molecules is simply inevitable in an organic chemical soup... we really should be checking the composition of organics on asteroids, I think.
If the test is robust enough to detect DNA-like structures (DNA/RNA/etc with maybe different base pairs, but the same general structure) or complex proteins, i would make a semi-educated guess that we'd be able to identify life.
If life is really exotic, then we might have to meet it face-to-face, and STILL not recognize it as such.
Jeremy
Well.
a) Working point for life is liquid-solid
b) To form structures, valence bonds are suitable
c) Combinatorics requires more than two valence bonds to make different molecules
d) bonds should be strong in comparison to temperature, yet not forever
All this make carbon a pretty likely candidate to be involved. Hydrogen is painly so abundant that it *will* be involved and oxygen is also not seldom. So it is not unlikely that life somewhere else may be based on a cemistry similar to ours.
So, what makes them think that a DNA based creature from MARS is going to be in any particular phylum that we know and/or can comprehend?
RS
Shoes for Industry. Shoes for the Dead.
Or is it already dead?
You are being MICROattacked, from various angles, in a SOFT manner.
That assumption is probably one of the things they are trying to prove, namely did Earth life originate off-planet? If they get a negative result because they don't find common ancestry, they've added some evidence against the panspermia theory.
Rule of Slashdot #0: You and people like you are not representative of the larger population. - A.C.
What makes them (or you) think that alien life will have any DNA at all?
The Earth and Mars have been exchanging biological material all along, through meteor impacts. To me, that makes it highly likely that there is a biosystem there, and fairly likely that there is some commonality between the two biosystems.
Question asked concerned a tool to find microscopic life. Microscopes are an excellent way to go about that. "Gorsh, nothing down there that looks like DNA" doesn't really answer the question, even if "yes, if it existed, it probably DID use a DNA analogue" is a good assumption.
Of course, finding DNA would be sweet, it's true.
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DNA information is still (generally) extracted chemically. Optical microsocopes will never have (thank you laws of physics!) the resolution required to be able to actually SEE DNA, and to send an electron microscope wouldn't be prudent at this juncture (thank you Dana Carvey!)
That's an interesting but tricky way to argue. After all, what we observe is conditioned on the fact that we are here now and hence that there needs to have been ample time for our own evolution. Frankly, as soon as we veer to close to anthropic arguments I'm no longer as confident as I once was about what arguments are valid. (But check out section 3.6 of Barrow and Tipler.)
Doesn't it make you feel good to know that our freedoms are protected by politicans, lawyers and journalists.
um... obviously from the Roswell bodies, duh!
Their working hypothesis (spelled out on the linked page) is that early in the development of microbial life there is (they claim) a statistically relevant chance that microbes developed on either Earth or Mars could have survived transfer from one planet to another via "meteoric exchange", which there would appear to have been a lot more of back ~3.5billion years ago when the first signs of modern-style microbes appear in the geological record.
Their assumption is that regardless of whether microbial life originated on Earth and possibly got blown to Mars during a major meteor impact, or vice-versa, if there are microbes growing in both environments now they'll be related.
I was going to say that you don't necessarily need specific bases for DNA amplification - there are some "whole genome amplification" techniques now that use a mix of small "random" primers to get amplification of (hopefully) most or all of the DNA in a sample rather than just one gene.
However, the description of the project does explicitly say they're planning to try to amplify 16s ribosomal DNA sequences, which are very handy for phylogenetic analysis of known terrestrial prokaryotes:
I'm a bit skeptical of the "universality" of "universal" primers, especially as to their usefulness after ~3,000,000,000 years of divergence. On the other hand, unlike some of the previous tests a positive result from this experiment would be very unambiguous if they can rule out contamination.
Hacker Public Radio is our Friend
yep, based on the single datapoint of earth life using DNA, it's reasonable to expect and look for ET DNA. However, after rolling a die once and getting 4 it would be similarly reasonable to expect subsequent rolls to also be 4.
Extrapolating based on a single datapoint is shaky at best. But without alternative substances to check for, DNA seems reasonable.
This reminds me of the old saying about when holding a hammer, everything looks like a nail.
I'm an individual! Just like everyone else!
From the marsrovers.nasa.gov website:
As of sol 1634 (Aug. 7, 2008), Spirit's total odometry remained at 7,528.0 meters (4.7 miles).
As of sol 1598 (July 22, 2008), Opportunity's total odometry was 11,725.96 meters (7.29 miles).
From Wiki and numerous other sources:
The marathon is a long-distance running event with an official distance of 42.195 kilometers (26 miles 385 yards) that is usually run as a road race.
As you can see, neither rover has even travelled a 1/2 Marathon.
snick, ;-P
but, wow, that's alot of driving to do 40-240M miles from home.
A simple application of Bayes' theorem tells us that the first is the least likely.
Hidden in that bunch of pseudo-mathematical drivel you still haven't got a clue what the probabilities are, so you're just making it up. Who says life is rare? We find life in the stranges places here on earth, maybe the solution to abiogensis (creation of life) is blatantly simple but we can't see it because there's so much life, so much competition and evolution it's difficult to imagine the most basic of forms life could take on. If there was any other phenomenon in the universe, any at all, my first thought would be "cool, we can have trinary star systems" not "cool, that must be the only trinary star system in the whole universe". Why really, should life here on Earth be unique?
Live today, because you never know what tomorrow brings
The scientific merit of this proposal is dubious at best.
My guess is that NASA is trying to ride the genomics wave and add something that is biological to get more people interested / get more funding. Politics over good science.
And that is what is so exciting yet frustrating about this type of thing. We know so very little that we don't even know the right questions to ask.
(much like sex )
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Did anybody else who's dowloaded the high res pic notice the white plastic pill bottle just right of center, about 1/3 of the way up from the bottom?
You never really know how close to the edge you can go until you fall off.
Yes. I know. That's why I keep talking about microscopic life. Microscopes are good at seeing microscopic life. The poster I was snarking at -- who, if he's reading this, has surely seen justice done at this point -- asked about microscopic life. So I mentioned a microscope.
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A microscope.
Images are nice, but a flow cytometer could test thousands of particles per minute and sort likely cells (using fluorescent stains for lipids, proteins, nucleic acids etc.) that alien microbes are much more likely to have than DNA similar enough to ours for PCR to work. Fancy flow cytometers can even snap pictures of the one-in-a-thousand particles that test positive.
Because it may not be alien. Martian rocks have been found on earth. They were apparently ejected into space during metor impacts on Mars, drifted through space, and eventually landed on Earth. It is reasonable to assume that some terrestrial rocks made the opposite journey. Life may have hitchhiked on these rocks in either direction. So Martian life may have originated on Earth, or vice versa.
The problem with microscopes is that you often have to know what you're seeing to understand what you saw.... High magnification images are complex and there are many inorganic reactions that can give you complicated looking structures. Most optical microscopy is done using a pretreated and often stained sample. Likewise electron microscopy. Many microscopic images look like semi random garbage on first look.
Now, it's a bit of a no brainer to put some sort of microscopy on future planet probes, but using them to find entirely new lifeforms is harder than you might think.
Faster! Faster! Faster would be better!
Oh my God. Thank the heavens that you are so much smarter than the scientists at NASA. What would they do without you! I highly recommend they bring you on staff, and you can be in the much vaunted position of "Minister of Keepin' it Real".
(A) we're either the first, or basically it takes ~X amount of time (X being the age of the universe) for intellegent life to evolve and we can't see ET sending us signals because he hasn't evolved yet or he's sending them from 200k light years away as we speak and wont see them for a very long time.
(B) Signal loss is so huge in the vastness of space we just cant possibily detect ET's version of Eight is Enough and Electro Woman and Dyna Girl. Maybe it's a blessing...
Yes we could.
Once again, another BS color image from Mars.
Anyone who cares to, do this: Open the image in Gimp or Photoshop.
Look at the per-channel histograms. You will see that someone compressed the Blue and Green channels before posting the image.
To fix:
Normalize each channel individually so that 0-255 spans the full channel range.
The result? Mars as Opportunity actually photographed it.
Does NASA really think that we are so simple-minded that we would be too confused and disoriented to see a Mars without red sky?
Mir tut es leid, Menschen daß Einfältigfehlersuchenbaumfolgendenaffen sind.
The physical detection approach is so 80's. Google for life's MySpace page instead.
Table-ized A.I.
Well it's classed as a research project, and I would think - just a guess mind you - that part of the problem may be to get around that issue. Whose to say the technique will look anything like the stuff we're using now.
A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort.
Informative but irrelevant.
The microscope is *instead of* looking for DNA. We already established we don't know what to look for with DNA, other than known types. But a microscope can *see*, no prior knowledge needed. We were kinda hoping that alien life would actually be in our dimension, so we should be able to see it.
I am hoping that when alien life is finally discovered, it will show that we are just another species differentiated by distance like the Galapagos island creatures. Humans are only really just starting high school in the learning stakes.
There's no reason I can think of to think that the end result of any abiogenesis process has to be DNA as the replicating molecule.
Earth is an incredibly diverse planet, environmentally speaking. The fact that no living things on Earth are non-DNA based makes me think that DNA is indeed the most-efficient way to handle replication. In other words, it's likely to outcompete any alternatives in Earth-like environments that are capable of supporting life to begin with.
Everything from the extremophiles found in deep-sea thermal vents to the highest mammalian forms is DNA-based. It's reasonable to start with DNA-based assumptions when you look for life elsewhere, abandoning those assumptions only after they fail to pan out.
Dahlmann tightly grips the knife, which he may have no idea how to use, and steps out into the plain.
I think that the anthropic principle is a null statement, and I agree with you that one should tread lightly if you get near it. I don't think it needs to be invoked in this case. I am more concerned about extrapolation from a single datum. The evidence seems to show that prokaryotic life arose quickly on Earth. There was then a really long period before the evolution of eukaryotic life, but that isn't germane here. If the evidence showed that there was a long sterile period before the appearance of prokaryotes, we could argue that life spontaneously arising is an unlikely event. You can still make the argument that the early appearance of prokaryotes just means that we got lucky, and it still is an unlikely event. However, that one data point we have shows that it can and did happen quickly.
Some mornings it's hardly worth chewing through the restraints to get out of bed.
It might be germane. If the step abiotic->prokaryotic is much more likely than the step prokaryotic->eukaryotic then we'd expect to see precisely the result we see: the first step happening quickly compared to the second step. This would be true even if both steps were a priori incredibly unlikely because we're looking at probabilities conditioned on the fact that eukaryotic life did arise.
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They're looking for a particular gene, which is found in all known life on Earth.
That's all just so much Genetics gibberish to me, but they also explicitly state in the proposal that they're working under the assumption that meteor impacts have transferred life between Earth and Mars in the past, and therefore, there is likely to be a hereditary relationship between Earth and Mars life. Based on those two assumptions, it seems like a reasonable experiment to perform.
And takes with it all of Victoria's Secrets...
You're kidding, right? If they get a negative result, then they think they don't have life at all and they dump the sample.
The most rabid believers in American Exceptionalism are the exact same people whose policies are destroying it.
It is reasonable to assume that some terrestrial rocks made the opposite journey.
No, it is reasonable to hypothesize that some terrestrial rocks made the opposite journey and then design the experiment to test that hypothesis. That's apparently not what's going on here.
The most rabid believers in American Exceptionalism are the exact same people whose policies are destroying it.
In the proposal, they state that they assume viable organisms are occasionally transferred between the planets on meteors. We only find one kind of life here on earth, the DNA-based kind. Since they assume that organisms can be occasionally transferred between Earth and Mars, if there is life on Mars, chances are it's DNA-based. Because either life developed on Mars and transferred here, or life developed here and tranferred there.
My question to you: what kind of machine would you put together that would search for microscopic life forms that are of a type we have yet to imagine?
:D
Duh, microscope.
It is always better to be a first grade version of yourself than a second grade version of someone else.
there is, it's called NMR, now, we'll leave the engineers to put an NMR machine and a robot that can prepare an NMR sample in a lander. Really, the best thing would be to bring the sample back to Earth, that's the only way to test them properly, a single instrument can never tell you what you have, you need multiple tests.
You could use Mass Spec to get some evidence of big molecules, it wouldn't tell you much about structure, but it would tell you that there's some big carbony molecules there, Beagle 2 had a mass spectrometer on board, shame it got splattered.
What if Tetris was invented by Nazis?
On the bright side, the website (http://www.opcva.com/watchdog/) is so god aweful looking, no one would take any of the information on it seriously. Note the fantastic cobweb wallpaper in pink- Wait wasn't this a 1998 geocities theme?
And instead of double-helix, it would be like.... ?
You know, there are some interesting suggestions (including using silicon instead of carbon and so on), but if you can not suggest other alternatives, why claim the current seemingly very sensible approach is brain-dead. I mean, one does have to define systems to detect _something_; so question remains, what would YOU try to detect?
I think the motivation for selecting this particular project was, that improving these techniques will likely have applications here on Earth too.
But looking for DNA is a pretty good guess for life for any planet that might have life on Earth-like conditions. It might very well be that DNA is the best molecule for genetic information in this kind of environment, and possibly even the only viable molecule in more extreme conditions like current Mars. It has, after all, "enslaved" RNA, and completely wiped out even traces of any other possible progenitors here on Earth...
Moreover, in the same way that carbon-base biology is far more energy efficient than silocon-based one is the most likely reason all life on earth is carbon-based despite overabundance of silicon on the Earth surface, it has been demonstrated that RNA/DNA is superior on a physico-chemical ground to any other potential data storing chemicals studied.
There may be somewhere life very different from what we could imagine, but the water/carbon/proteins combination is by far the most efficient one scientists could imagine, so it's logic to bet on that base, at least for planets like Mars that are not that different from Earth.
"(A) we're either the first, or basically it takes ~X amount of time (X being the age of the universe) for intellegent life to evolve and we can't see ET sending us signals because he hasn't evolved yet or he's sending them from 200k light years away as we speak and wont see them for a very long time."
it's very unlikely that intelligent life evolve in two (or more) distinct point of the univerve within 0.0016% of current universe age. The problem might also be far worse: imagine a million civilizations existed in our galaxy before us and lasted an average 10000years, even when forgetting point B, that would still make a very little chance that the age and distance of at least one of those civilizations match enough to allow us to receive a signal.
"(B) Signal loss is so huge in the vastness of space"
Human radio emmisions are masked by thermal background noise before they reach Saturn orbit, so don't worry about Omicronians. To reach interstellar distances, you either need to aim at a particular target and shoot a very focussed signal or blow up supernovaes in a kind of ultimate morse code.
You'd be looking for an anaerobic electron transport chain first and foremost, like sequences coding for fumarate, nitrate or nitrite reductases or the common terrestrial proton pumps.
There are a variety of other well-conserved genes that would be worth searching for.
Any match would be pretty conclusive evidence of common ancestry with terrestrial microbes, and actual Earth-like life.
We can also just take a stab in the dark and hope that our post-denaturation sample has anything in it that appeals to Taq. We are not so much interested in doing a size separation in that sort of experiment, as seeing if there has been any polymerization at all. We can then try to do something like Sanger or Fiers on the result.
On the other hand, if we can demonstrate the presence of organized nucleic acids but not common DNA or RNA sequences, or anything that works with our polymerases, then there'd be lots of headscratching about how to drop an SEM, AFM and an X-Ray crystallography lab onto a sample of Mars (or vice versa), and hope that we can find an analogue to cells or capsids encapsulating the not-very-like-us nucleic acids.
So in other words, "they don't". Taq will probably do nothing with completely alien nucleotide polymer fragments. If there is any evidence of polymerization at all, then to quote Steve Jobs, "Boom!".
OK, I'll bite.
I'd put in an MS (mass spectrometer), possibly front-ended with a gas chromatograph.
No, it's not (directly) capable of identifying the chemistry of life as found on an alien world. But what it is intended to do is (1) identify with good accuracy the components of the environment ; (2) get reasonably good concentrations for those components. Then, if there are significant disequilibria, you've got life. Detection part of the job is done.
The same equipment would also have a pretty good chance of characterising the major components of any "obviously living" matter fed into it (take a Japanese schoolgirl on the mission, then chop off any tentacles that come creeping out of a swamp to molest her).
But I'd have to say that we should be able to detect the presence of life long before landing a probe. Any or all of the following should give us an adequate clue that there's something alive down there : atmospheric composition ; presence of seasonal changes ; reflection of only certain colours of light which indicates that something non-mineralogical is using a large chunk of the incoming spectrum.
Designing something algorithmic to work this out without human intervention is a challenge. But probably less of a challenge than building an interstellar craft that can carry humans.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
We've attempted other types of "life" instruments and they didn't show anything. We've found multiple sites that show signs of or proof of the existence of liquid water at some point Martian history. So why not take a different approach from the previous efforts? If any instrument detects life on Mars but can't bring that life back to Earth, the people who don't want to believe in life on Mars will argue that the life originated on Earth not Mars. One of the benefits of a DNA instrument is that you are more likely to be able to eliminate the possibility that the microbe originated on Earth rather than Mars.
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