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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?
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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)
It would use almost no gas, almost never break down, but there would be a 4 to 40 minute lag between when you push the gas pedal and when it moves. :-D
"Bah!" - Dogbert
"...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.
Well, it has 33% of those features in common with your average US* made car then.
* please replace with your own country if you are not from the US, to achieve maximum insult level.
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?
Another lesson to learn is that despite highly publicized mistakes, NASA does have a lot engineers who are both brilliant and wise.
"I zero-index my hamsters" - Willtor (147206)
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 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.
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.
A microscope.
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Actually, there are fairly good odds that alien life uses DNA in a similar way that we do.
Primarily because proteins/amino acids are the only chemical family that has the variation needed for life to function. Sugars don't have the variety necessary and lipids have difficulty interacting with aqueous environments. the 20 amino acids we use cover the full range of conditions, acid/base/hydrophobic/hydrophilic/big/small/odd (proline). It is unlikley that other lifeforms will use significantly more or less amino acids even if the specific chemistry is slightly different.
The biggest problem with proteins is that they can't store information. They can't form complements and unfolding a protein to directly read off the amino acid sequence typically destroys the original protein. Life needs a repository of information that is self correcting and is non-destructive to existing proteins.
Since sugars and amino acids are common (sugar forms easily and amino acids are necessary for efficient life) it is not unlikley that DNA/RNA (which is based off of these two molecular families) would form and it DOES fit the bill for data storage. Since simplicity provides stability, it is unlikley that a huge number of different base pairs would be used so either 2 or 4 bases are likley. Due to space limitations it is very unlikley that a DNA/RNA system would use more than 3 hydrogen bonds and 1 hydrogen bond is too weak. Therefore the list of usefull base pairs drops to either 2 or 3 bonds and we call them adenine, thymine, guanine and cytosine.
I freely admit that this is based off of an N of 1. But even with that said it is important to remember that life is hard and the simpiler/more efficient a system is the better able a life form is to survive. While the system we use isn't mandatory, it is very likley that it is representative of other similarly effective systems.
A PCR system would be able to detect the residue of a lifeform that looks even remotly like us on a molecular level. Since we know our system works and we have no knowledge of a different life system it is only reasonable to look for a system we know works. PCR is our best bet for identifying life.
Another lesson to learn is that despite highly publicized mistakes, NASA does have a lot engineers who are both brilliant and wise.
I don't think anyone has questioned that. But one mistake from one engineer and it's game over, so it takes a very unique process to deliver on that. Even in healthcare people die because of mistakes, and while fatal to the patient it's not like the hospital will crash and burn because of it. It doesn't matter how remote in the wilderness you are here on Earth, it's a lot easier to fix or try again than any space probe. I think SpaceX is starting to figure out how hard it is to avoid all potential problems at once...
Live today, because you never know what tomorrow brings
And when one of the wheels seizes up, support will tell you to be excited because your car is now also a plow!
.evom ton seod gis eht
http://www.marccarson.com/images/slashdot-mars-panorama.jpg
There you go...491KB.
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.
Here's a page that attempts to rebut this: http://www.donaldedavis.com/2008%20new/CLRMARS.html.
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