Enough already! Flowing water existed on Mars long enough to
hugely modified the landscape. That
provided a media allowing for life to arise and it most certainly did. Once the temperature dropped we can be sure
it went back into hibernation and is functioning now much deeper in the rock.
Other work suggests something
much more interesting than cellular life but that is a different story.
We now know enough about the
formation of early life on a planet to have confidence that we will encounter
it on Mars in a primitive form, whatever that means anymore. The key question was whether moist conditions
ever existed and we seem to have arrived at a positive consensus on that.
Yes Virginia
This should be a huge media story
promoted to bring support for the investment in a Mars expedition to a peak of
enthusiasm.
Mars was earthlike for a few hours a day': Could it have supported
life?
Last updated at 9:07 AM on 13th October 2011
Mars once had 'earthlike' conditions for at least a few hours a day,
according to new research.
The findings make it more plausible that the planet could have
supported life, though if the warm temperatures were only temporary that still
remains unlikely.
Nonetheless, the pioneering findings were described as 'remarkable' and
'really cool' by one of the study's authors.
Evidence: A study of these carbonate minerals which formed on a Martian
meteorite suggest that the planet was once much warmer
The research, which analysed the minerals in a four billion-year-old
Martian meteorite, provides the first strong evidence that Mars used to be
warmer and wetter than it is now.
The minerals seem to have formed at around 18c (64f).
'The thing that’s really cool is that 18 degrees is not particularly
cold nor particularly hot,' says Woody Fischer, a scientist at the California
Institute of Technology (Caltech) and co-author of the paper.
'It’s a remarkable result.'
Knowing the temperature of Mars is crucial to understanding the
planet’s history - its past climate, and whether it once had liquid water.
Antique: The rock analysed in this study is one of the oldest now on
Earth
The Mars rovers and orbiting spacecraft have found ancient deltas,
rivers, lakebeds, and mineral deposits, suggesting that water did indeed flow.
Because Mars now has an average temperature of -63c, the existence of
liquid water in the past means that the climate was much warmer then. But
what’s been lacking is data that directly points to such a history.
'There are all these ideas that have been developed about a warmer,
wetter early Mars,' Fischer says. 'But there’s precious little data that
actually bears on it.' That is, until now.
Another author of the research, John Eiler, said: 'It’s proof that
early in the history of Mars, at least one place on the planet was capable of
keeping an Earthlike climate for at least a few hours to a few days.'
To make their measurement, the researchers analysed one of the oldest
known rocks in the world: ALH84001, a Martian meteorite discovered in 1984 in
the Allan Hills
of Antarctica .
The meteorite probably started out tens of metres below the Martian
surface and was blown off when another meteorite struck the area, blasting the
piece of Mars toward Earth.
Exploration: The study has done more than landers to work out the
historical temperature on the surface of Mars
The potato-shaped rock made headlines in 1996 when scientists
discovered tiny globules in it that looked like fossilized bacteria.
But the claim that it was extraterrestrial life didn’t hold up upon
closer scrutiny. The origin of the globules, which contain carbonate minerals,
remained a mystery.
Suggestions about their origin depend on what temperature they formed
at, with previous suggestions ranging from below freezing to 700c.
Finding the temperature through independent means would therefore help
narrow down just how the carbonate might have been formed.
The researchers turned to clumped-isotope thermometry, a technique
developed by Eiler and his colleagues that has been used for a variety of
applications, including measuring the body temperatures of dinosaurs and
determining Earth’s climate history.
In this case, the team measured concentrations of the rare isotopes
oxygen-18 and carbon-13 contained in the carbonate samples.
Carbonate is made out of carbon and oxygen, and as it forms, the two
rare isotopes may bond to each other - clumping together, as Eiler calls it.
The lower the temperature, the more the isotopes tend to clump. As a
result, determining the amount of clumping allows for a direct measurement of
temperature.
Could this wet and warm environment have been a habitat for life? Most
likely not, the researchers say.
These conditions wouldn’t have existed long enough for life to grow or
evolve - it would have taken only hours to days for the water to dry up.
Still, these results are proof that an earthlike environment once
existed in at least one particular spot on Mars for a short time, the
researchers say.
What that implies for the global geology of Mars - whether this rock is
representative of Martian history or is just an isolated artifact - is an open
question.
Read more:
No comments:
Post a Comment