Ideally, we really want some nice, well-adapted RNA organisms or their traces, even if the DNA guys ate them later - not a wholly unlikely outcome, either! Would fossil metabolites of RNA organisms demonstrate different chirality to DNA critters (eg perhaps none at all), and would these perhaps be detectable? That would be a serious result if discovered! It might even be worth looking at Pre-Cambrian rocks on Earth (and, as I've oft repeated, on the Moon when we eventually start to strip mine it).If it is DNA based, then the best we can hope for is the date of a last common ancestor, and as crust material flows back and forth across the Inner Solar System then that might not help.
Is it too much of a reach to suggest that at one in their early evolution that Mars & Earth were identical in their potential for life to evolve on them?
If the chemical basis is the same, it *can* be contamination, but still might not be, inasmuch as life chemistry might well reinvent the wheel in all sorts of places. Ideally, we really want some nice, well-adapted RNA organisms or their traces, even if the DNA guys ate them later - not a wholly unlikely outcome, either! Would fossil metabolites of RNA organisms demonstrate different chirality to DNA critters (eg perhaps none at all), and would these perhaps be detectable? That would be a serious result if discovered! It might even be worth looking at Pre-Cambrian rocks on Earth (and, as I've oft repeated, on the Moon when we eventually start to strip mine it).
If it is DNA based, then the best we can hope for is the date of a last common ancestor, and as crust material flows back and forth across the Inner Solar System then that might not help.
As for forward contamination, the Soviet landers (yes, plural - just because we only have an idea of what happened to one of them doesn't mean at least one of the others didn't land, even if in (ahem) a disassembled condition) and parachutes don't appear to have been sterilised; efforts were made with Viking, but not so much with subsequent US landers, deliberate or not. In some respects, a visit to the Mars-3 site by a nice, sterile sample-return vehicle might be seriously interesting, and might even prove that there is life on Earth, and even (briefly) on Mars...
We do already have an example of a life-bearing object suffering a meteoric-like entry into a planetary atmosphere, and the inhabitants of said object not only surviving, but breeding: the famous Columbia worms. OK, we're not talking about lengthy exposure to space conditions, but we've already seen the unexpected survival of reasonably advanced organisms, which might make it even more likely that tougher varmints could do their thing!
Glad to see Noffke's paper discussed! There is some slight and cautious blog activity out there...I'm not as conversant with stromatolites as Dalhousie (astrobiology a recent hobby). But if some people refuse to see all stromatolites as bigenic the microbialites are much more testable since there isn't any abiotic similars (according to Noffke). And besides the 3 macrosignatures (morphology, association and succession) she lists 9 microsignatures that are checked (for confirmation).
Since Earth geology is much more complex (~4000 vs ~1000 minerals according to Hazen), the final item on Noffke's diagnostic list, differentiation between biotic and abiotic signatures should morally be quick. Perhaps the rovers together has massed enough material to check that point.
If the emerging thermodynamics of replicators is correct, the NET is driven by replication (so you don't dissociate as fast as you replicate) and exponential growth (so evolution can happen). That puts severe constraints on early biological takeover. RNA is the only known polymer that can make the replicator bound with early inefficient metabolic NET engines (electron bifurcators). And it in turn is chemically constrained to use 4 bases out of a very limited set, to balance replication vs enzymatic efficiency.On the other hand, RNA cells are not necessarily chirally constrained, selfish ribozymes that co-evolve to replicate the opposite chirality is smaller and more efficient than a monochiral cell. It is first with the evolution of protein translation that chiral symmetry has to be broken.The chemical constraints are loosened then replication and translation separates. There are many potential alternatives to DNA, but it is a simple enough modification of RNA so quite likely. But here is the kicker, independent of above discussed chemical constraint: we can trace ancestry through phylogenies all the way to the DNA LUCA. (And in the case of tRNA and the rRNA preserved core back to the RNA UCA lineage.) We can see differences between ancestors of genes and easily distinguish between different roots in DNA (or analog) cells.
Back to sleep then.
One open question from those is seasonal variation. I'd expect the MSL team to publish atmosphere results for a full Mars year (or more) at some point, but if they have I wasn't able to find it.
Results of our analyses reveal variations in both 𝛿18O and 𝛿13C that suggest a seasonal trend in the isotopic composition of atmospheric CO2. We will examine this finding particularly in the context of isotopic fractionation expected during CO2 condensation and sublimation cycles [15] and discuss implications for the martian atmosphere.
Interferences at m/z 12 and 13 have been more problematic in atmospheric experiments performed since SAM began analyzing solid samples, which introduced products of derivatization reagent N-methyl-N-(tert-butyldimethylsilyl)-trifluoro-acetamide (MTBSTFA) into the gas manifold
NASA's Curiosity Mars rover is expected to remain stationary for several days of engineering analysis following an onboard fault-protection action on Feb. 27 that halted a process of transferring sample material between devices on the rover's robotic arm.Telemetry received from the rover indicated that a transient short circuit occurred and the vehicle followed its programmed response, stopping the arm activity underway at the time of the irregularity in the electric current.
Managers of NASA's Curiosity Mars rover mission expect to approve resumption of rover arm movements as early as next week while continuing analysis of what appears to be an intermittent short circuit in the drill.
A fatty acid might be among organic molecules discovered on Mars by Nasa's Curiosity rover.However, it's not possible at this stage to determine whether the compound has a biological or non-biological origin.And contamination could still be responsible for the finding.The results come from Curiosity's SAM instrument, and were presented at the 46th Lunar and Planetary Science Conference (LPSC) in Texas.