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Solar burps may be behind loss of Martian water
In this section n What now for gene editing after leukaemia success, page 10 n Free diving with elusive hammerhead sharks, page 12 n Pitfalls of the UK’s “snoopers’ charter”, page 20
Solar burps may be behind loss of Martian water THE Martian weather report is in. Information beamed back by NASA’s MAVEN spacecraft, which has been studying Mars’s atmosphere from orbit since September 2014, offers a new view of the Red Planet’s history and could help pave the way for crewed missions. One of Mars’s long-standing mysteries is what happened to its water. Geological evidence found by NASA’s Curiosity rover suggests the planet was once wet enough to host lakes and rivers, but barring a few salty streaks we don’t see much sign of these today. “We’re trying to understand what changes in the climate have occurred and what drove them in order to go from that warm wet planet to today’s cold, dry, more desert-like environment,” says Bruce Jakosky of the University of Colorado, Boulder, who heads the MAVEN mission. To that end, MAVEN is studying how water and other molecules could have escaped through the planet’s atmosphere and out into space. In March this year, it watched as the sun burped out a coronal mass ejection (CME), a mix of gas particles and magnetic field lines. When this mass slammed into Mars, it generated a strong electric field in the upper atmosphere, giving a large number of oxygen and carbon dioxide ions sufficient energy to escape into space (Science, doi.org/83k).
NASA/GSFC
indeed tantalising, but would need to be confirmed,” says Ehrlich. “I am not entirely sure what the results really mean,” says James McInerney at the University of Manchester, UK, whose research looks at the origins of the three known domains of life. He suspects that the unusual genes will turn out to belong to fairly ordinary microbes – particularly since researchers are beginning to appreciate that gene diversity might be more extreme than once thought. That would still be an exciting find, he says. “It might hint at new metabolic processes at work in our guts.” McInerney also points out that the proposed fourth doma in of life still eludes us even after 25 years of sampling DNA from the environment. But Lopez and –Teeming with alien life?– Bapteste argue this is because recognising completely new that defy classification, especially microbes is, by definition, as we know nothing about the a challenge. microbes that carry the strange All can agree that the true genes. “Let’s wait to see how significance of the new findings unusual the organisms are,” won’t become clear until they he says. In particular, it would have actual cells containing the help to know about their size and unusual genes – the next task on their internal structure, including the agenda. “The good news is the ribosomes they use to make we now know something about proteins. The cell’s metabolic them that could help us to fish processes might be unusual too, them out,” says Bapteste. Like says Bapteste. most microbes, they probably But there’s no reason why we can’t be grown in the lab, but couldn’t find a new domain of life Bapteste says developments in inside us. “Scientists have found a a technology called single cell huge diversity of microbes in the genomics should soon offer a human gut, so I would not expect way to sequence the genome of it to be necessarily hostile to individual microbes, even if different life forms,” says they can’t be cultured. Bapteste. Last year, Dusko Ehrlich If the results reveal microbes at the French National Institute as unconventional as their genes for Agricultural Research in Jouyappear to be, biology might en-Josas was part of a consortium change – just as it did 30 years that updated the catalogue of ago when researchers first genes in the gut microbiome, realised that the archaea formed expanding our estimate from 3.3 a distinct third domain of life. million to 9.9 million. “The gut “The discovery of archaea microbiome is not such a wellrevolutionised our fundamental known playground,” he says. knowledge in biology,” says But the big question remains: Bapteste. For now, he says, we could it really play host to should remain cautious. “These microbes from a fourth domain? deep lineages, if they exist, still “The evidence is suggestive and need to be captured.” n
This small-scale stripping of Mars’s atmosphere could be an echo of the past. It’s thought that the sun was once more active, with a greater frequency and intensity of CMEs. That would have stripped more gas out of the atmosphere, leaving Mars barren. MAVEN has also performed a number of “deep dips” into the atmosphere, gathering data that could help astronauts land on the surface by using the atmosphere to safely slow down (Geophysical Research Letters, doi.org/85z). Jakosky says MAVEN could also determine whether Mars’s ionosphere
“We’re trying to understand why Mars went from a warm, wet planet to a cold, dry, desert-like one” is strong enough to bounce radio waves off, letting astronauts converse over longer distances on the surface. In general, he thinks MAVEN is laying down a science baseline that future missions will explore further. He points to the opening of the recent film The Martian, in which astronaut Mark Watney and his crew are gathering rock samples. “What they’re doing is looking to answer the questions that we’re helping to pose right now,” he says. “I think Mark Watney and his fellow astronauts would have been very familiar with the MAVEN mission.” Jacob Aron n
–Watch out for the sun– 14 November 2015 | NewScientist | 9
Solar burps may be behind loss of Martian water THE Martian weather report is in. Information beamed back by NASA’s MAVEN spacecraft, which has been studying Mars’s atmosphere from orbit since September 2014, offers a new view of the Red Planet’s history and could help pave the way for crewed missions. One of Mars’s long-standing mysteries is what happened to its water. Geological evidence found by NASA’s Curiosity rover suggests the planet was once wet enough to host lakes and rivers, but barring a few salty streaks we don’t see much sign of these today. “We’re trying to understand what changes in the climate have occurred and what drove them in order to go from that warm wet planet to today’s cold, dry, more desert-like environment,” says Bruce Jakosky of the University of Colorado, Boulder, who heads the MAVEN mission. To that end, MAVEN is studying how water and other molecules could have escaped through the planet’s atmosphere and out into space. In March this year, it watched as the sun burped out a coronal mass ejection (CME), a mix of gas particles and magnetic field lines. When this mass slammed into Mars, it generated a strong electric field in the upper atmosphere, giving a large number of oxygen and carbon dioxide ions sufficient energy to escape into space (Science, doi.org/83k).
NASA/GSFC
indeed tantalising, but would need to be confirmed,” says Ehrlich. “I am not entirely sure what the results really mean,” says James McInerney at the University of Manchester, UK, whose research looks at the origins of the three known domains of life. He suspects that the unusual genes will turn out to belong to fairly ordinary microbes – particularly since researchers are beginning to appreciate that gene diversity might be more extreme than once thought. That would still be an exciting find, he says. “It might hint at new metabolic processes at work in our guts.” McInerney also points out that the proposed fourth doma in of life still eludes us even after 25 years of sampling DNA from the environment. But Lopez and –Teeming with alien life?– Bapteste argue this is because recognising completely new that defy classification, especially microbes is, by definition, as we know nothing about the a challenge. microbes that carry the strange All can agree that the true genes. “Let’s wait to see how significance of the new findings unusual the organisms are,” won’t become clear until they he says. In particular, it would have actual cells containing the help to know about their size and unusual genes – the next task on their internal structure, including the agenda. “The good news is the ribosomes they use to make we now know something about proteins. The cell’s metabolic them that could help us to fish processes might be unusual too, them out,” says Bapteste. Like says Bapteste. most microbes, they probably But there’s no reason why we can’t be grown in the lab, but couldn’t find a new domain of life Bapteste says developments in inside us. “Scientists have found a a technology called single cell huge diversity of microbes in the genomics should soon offer a human gut, so I would not expect way to sequence the genome of it to be necessarily hostile to individual microbes, even if different life forms,” says they can’t be cultured. Bapteste. Last year, Dusko Ehrlich If the results reveal microbes at the French National Institute as unconventional as their genes for Agricultural Research in Jouyappear to be, biology might en-Josas was part of a consortium change – just as it did 30 years that updated the catalogue of ago when researchers first genes in the gut microbiome, realised that the archaea formed expanding our estimate from 3.3 a distinct third domain of life. million to 9.9 million. “The gut “The discovery of archaea microbiome is not such a wellrevolutionised our fundamental known playground,” he says. knowledge in biology,” says But the big question remains: Bapteste. For now, he says, we could it really play host to should remain cautious. “These microbes from a fourth domain? deep lineages, if they exist, still “The evidence is suggestive and need to be captured.” n
This small-scale stripping of Mars’s atmosphere could be an echo of the past. It’s thought that the sun was once more active, with a greater frequency and intensity of CMEs. That would have stripped more gas out of the atmosphere, leaving Mars barren. MAVEN has also performed a number of “deep dips” into the atmosphere, gathering data that could help astronauts land on the surface by using the atmosphere to safely slow down (Geophysical Research Letters, doi.org/85z). Jakosky says MAVEN could also determine whether Mars’s ionosphere
“We’re trying to understand why Mars went from a warm, wet planet to a cold, dry, desert-like one” is strong enough to bounce radio waves off, letting astronauts converse over longer distances on the surface. In general, he thinks MAVEN is laying down a science baseline that future missions will explore further. He points to the opening of the recent film The Martian, in which astronaut Mark Watney and his crew are gathering rock samples. “What they’re doing is looking to answer the questions that we’re helping to pose right now,” he says. “I think Mark Watney and his fellow astronauts would have been very familiar with the MAVEN mission.” Jacob Aron n
–Watch out for the sun– 14 November 2015 | NewScientist | 9