28
September 2015
Salty water seen flowing on Mars, not far from
Curiosity rover
The dark streaks in this picture may
be signs of salty water
JPL/NASA
NASA’s Mars Reconnaissance Orbiter has
captured the strongest evidence yet that salty liquid water flows on the
planet’s surface during warm seasons.
Whether or not these salty flows could sustain life depends on
how salty they are, says Lujendra Ojha of the Georgia Institute of Technology in Atlanta, who
has reported the findings, along with his colleagues. “If the water is
completely saturated with perchlorates [hydrated salts], then life as we know
it on Earth wouldn’t be able to survive in that sort of concentrated water,” he
says. “But if the water only has a tiny percentage of perchlorates in it, then
I think we should be fine.
Recurring slope lineae – dark streaks that appear, get longer,
and fade in each Martian year – have long been thought to
represent signs of flowing water. Now
that idea has been backed up by data from the Orbiter’s onboard spectrometer, named CRISM, which analyses reflected sunlight to detect patterns
that indicate what minerals are present on the surface.
Salts can absorb water from the
atmosphere and lower the freezing point of water, making it possible for liquid
water to exist even in the cold Martian climate. Spectral data from four
locations with recurrent slope lineae reveal the presence of hydrated salts,
which are most likely to be magnesium perchlorate, magnesium chlorate and
sodium perchlorate.
Although not examined in the current study, features resembling
recurrent slope lineae were observed this year in Gale crater, raising the possibility that the Curiosity rover could
look for more clues up close.
Help is near
The most promising location is about 50 kilometres from the
Curiosity landing site. Curiosity has already found evidence of perchlorates at Gale crater, as well as organic compounds.
Confirmation of flowing water on the surface would add
substantial weight to calls for NASA to commit more strongly to searching for
life on Mars. In the Atacama desert, one of the
most hostile environments on Earth, communities of microbes are able to survive
on moisture in the ground created by salts absorbing water from the atmosphere.
Some think, similar microbes could live on Mars.
More signs of water?
JPL/NASA
A number of astrobiologists criticised NASA when plans for its next rover, Mars 2020, left out DNA sequencers and other
devices designed to look for living organisms.
But many scientists would not be convinced by evidence from a
rover. Definitive proof of life on Mars would require samples to be brought
back to Earth. Mars 2020 will store samples to be brought home in a later mission.
“The only thing we can really assert
is that the places we’re finding are probably more habitable than the rest of
the planet, which is bone dry,” says Ojha.
Journal reference: Nature Geoscience, DOI:
10.1038/ngeo2546
Structure
of the Lead:
WHO-NASA
WHEN-28 September 2015
WHAT-water on Mars
WHY-not given
WHERE-Mars
HOW-Curiosity rover
Keywords:
1. saturated 飽和的
2. perchlorates 高氯酸鹽
3. spectral 光譜
4. magnesium perchlorate 高氯酸鎂
5. sodium perchlorate 高氯酸鈉
6. Gale crater 蓋爾隕石坑
7. Confirmation 確認
8. hostile 敵對的
9. microbes 微生物
10. organisms 生物
作者已經移除這則留言。
回覆刪除NASA found the evidence that salty liquid water flows on Mars.It was a good news.Scientists have done many research of it before.But there were few evidences to support it.Maybe we even can find other living beings exist on Mars.I expect to hear their new discovery next time.
回覆刪除After many years finally allow the machine landing on Mars, it is really a significant step. There are some organics that was found on Mars. I hope one day they can find a planet similar with Earth. Maybe one day we can live on Mars. But in recent year, it should not be come true. I am hoping to quickly achieve.
回覆刪除Scientists found the evidence that salty liquid water flows on Mars.It means that there may be have biological life on Mars. Bring this good news is a robot named Curiosity rover. We are looking forward to the the news it brought next time.
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