|To boldly go – or not: simulation of the proposed mission to Jupiter’s icy moon, Europa |
Wednesday, March 30, 2011
Are Earthlings From Mars? New Tool May Reveal Your Alien Ancestry
by Mike Wall, SPACE.com Senior Writer
Date: 23 March 2011 Time: 03:31 PM ET
|A photo of Mars from NASA's Viking spacecraft, which launched in 1975.|
CREDIT: The Viking Project/NASA
This story was updated at 6:50 p.m. EDT.
It's possible that the family tree of all life on Earth has its roots on Mars — and a new device could put that theory to the test in a few years, researchers say.
Researchers are developing an instrument that would search through samples of Martian dirt, isolating any genetic material from microbes that might be present — bugs that are living or that died relatively recently, within the last million years or so. Scientists could then use standard biochemical techniques to analyze any resulting genetic sequences, comparing them to what we find on Earth.
"It’s a long shot,” said MIT researcher Chris Carr, who's working on the life-detecting device, in a statement. "But if we go to Mars and find life that’s related to us, we could have originated on Mars. Or if it started here, it could have been transferred to Mars." [5 Bold Claims of Alien Life]
Either way, Carr added, "we could be related to life on Mars. So we should at least be looking for life on Mars that’s related to us."
Ancient Martian life?
The idea that all Earth life could be descended from Martian organisms may not be fully mainstream — but it's not too crazy to consider, either. While the Martian surface appears to be cold, dry and lifeless today, there is plenty of evidence that the planet was much warmer and wetter in the distant past, billions of years ago.
Here on Earth, life almost invariably occupies any niche that contains liquid water. So ancient Mars may have once supported some form of life — perhaps even before Earth did, researchers said.
If that's the case, these Mars microbes may have colonized Earth, zipping through interplanetary space aboard rocks blasted off the Martian surface by asteroid impacts. An estimated 1 billion tons of Martian rock have made this journey over the years, researchers said.
And microbes are incredibly hardy, so it's possible that some bugs could have survived the asteroid impact and the trip through space to a new planet, they added. Orbital dynamics show that it's about 100 times easier for rocks to travel from Mars to Earth than the other way around, Carr said.
So if life got started on Mars first, it's possible that every living thing on Earth can trace its lineage back to a Martian.
"It is not implausible that life on Mars will be related to life on Earth and therefore share a common genetics," said astrobiologist Chris McKay of NASA's Ames Research Center in Moffett Field, Calif. "In any case, it would be important to test this hypothesis."
Digging through Martian dirt
The proposed instrument, being developed by researchers at MIT and Harvard, aims to do just that. The device — known as the Search for Extra-Terrestrial Genomes, or SETG — would take a sample of Martian soil and process it to separate out any possible organisms, living or dead (within the last million years or so).
While finding anything on the Martian surface might be a long shot, digging a little deeper could bear fruit; researchers have found evidence over the years that liquid water may lurk underground. [Video: The Changing Face of Mars]
Also, subterranean environments are more protected from the harmful ultraviolet radiation bombarding the Martian surface, making life more likely to survive underground.
"We think it's much less likely that we would find something on the surface or in the top centimeters than if we went down a meter or more," Carr told SPACE.com. "The deeper we could go on Mars, the better."
So samples could be dredged up by a rover equipped with a deep drill. If any life-forms are present in the dirt, the SETG would amplify their DNA or RNA, then search for genetic sequences that are common in Earth organisms. Such analysis might be able to tell researchers how closely related any possible Martians are to us.
This would all be done on the Martian surface, without the need to lug dirt back to Earth, Carr said.
"But I would argue that it would sure be interesting to return samples if we found something," he added.
The work is worth doing to better understand the origin and evolution of life on Earth, researchers said. But there are other, more practical reasons to look at the DNA of any potential Martians, too.
NASA and other space agencies, for example, would want to how much of a disease risk Martian organisms might pose to future astronauts.
"From an astronaut health and safety point of view and from a return-sample point of view, there is more to worry about” if there are organisms closely related to us on Mars, McKay said. For example, microbes that are similar to us are much more likely to have the chance to be infectious than totally alien organisms would be.
The SETG could also help detect biological contamination that spacecraft may have brought to Mars from Earth, Carr said.
The researchers presented a summary of their proposed life-detecting instrument earlier this month at the IEEE Aerospace Conference in Big Sky, Mont.
A few years away
The SETG is not yet ready to catch a rocket to Mars. A working version of the instrument will need to do three things: isolate biological material, amplify and detect DNA and then sequence it. Researchers have built a prototype instrument, about the size of a shoebox, that can perform the middle step, Carr said.
They're working on adding the other two capabilities, and a fully functional prototype could be ready to go pretty soon.
"The goal is to have that system in two years, and then to put it through its paces in some challenging environments," Carr said.
Such environments could include Antarctica or Chile's Atacama Desert, Carr added. If the SETG passes its Martian-analog tests, the next step would be building a flight-ready instrument. If all goes well, that could happen by 2018 or so.
That timeline could make the SETG a candidate instrument for two rover missions slated to launch around 2018 — the European-led ExoMars and NASA's Mars Astrobiology Explorer-Cacher (MAX-C). Both the ExoMars and MAX-C rovers will sport drills capable of getting at least a meter under the Martian surface.
Carr said such missions would be good fits for the SETG, but he stressed that the instrument hasn't been selected for any Mars mission as of yet.
Ramping up the search for Martian life
If the SETG does get incorporated into a Mars mission, it would mark the first time that an instrument made its way to the Red Planet specifically to look for life since 1976, when NASA's twin Viking landers found tantalizing, but ambiguous, results.
An instrument aboard NASA's Mars Science Laboratory rover— also known as Curiosity — will investigate chemistry relevant to life when it arrives on the Red Planet in August 2012. The SETG, by contrast, directly addresses Earth-like molecular biology.
The SETG could someday have applications aside from searching for life on Mars, Carr said. For example, the tool could one day help astronauts diagnose infections in space and monitor their environments. But he hopes the instrument gets a chance to show its stuff on the Red Planet.
"Mars may or may not have life," Carr said. "If it does, we think there's a chance it could be related to us. If in fact it is, we want to find it."
Monday, March 28, 2011
Nasa’s trip to Mars is mission improbable
Edited by Clive Cookson
Published: March 18 2011 22:07 | Last updated: March 18 2011 22:07
Planetary scientists have issued their official wish list for unmanned space missions to explore the solar system over the next decade. Top priority of the report from the US National Academy of Sciences is robotic exploration of Mars. The second mission on the list is a visit to Jupiter’s icy moon Europa and its subsurface ocean – seen as one of the most promising environments in the solar system for supporting life. Third priority would be a mission to investigate the interior structure, atmosphere and composition of the outer planet Uranus, one of the least understood large bodies in the solar system.
The 400-page report is the result of a thorough review of the options by 17 senior planetary scientists. It will carry great weight with its sponsor, the US space agency Nasa. But whether it turns out to be a practical guide for Nasa to plan future missions – or a fantasy list – depends on how much money the agency receives from the US Congress for space science.
Latest signals from the Washington budgetary process are not encouraging. The report was prepared on the basis of Nasa’s 2011 budget, which has still not been enacted as a result of the Obama administration’s fiscal standoff with Congress. The proposed 2012 budget gives considerably less money to space science. “Our recommendations are science-driven, and they offer a balanced mix of missions – large, medium and small – that have the potential to greatly expand our knowledge of the solar system,” says Steven Squyres of Cornell University, who chaired the academy’s review panel. “However, in these tough economic times, some difficult choices may have to be made.”
The report says that if Nasa does not have enough money to support its three big favoured missions, then one or more of these should be delayed, scaled back or cancelled, so that the agency can continue to fund a steady stream of smaller, less expensive missions. Candidates for these include returning a sample from a comet to earth, probing Saturn’s atmosphere, landing on the surface of Venus, visiting more asteroids and putting a network of geophysical observatories on to the moon. The most expensive of the three top priorities is the Jupiter Europa Orbiter, for which an independent estimate put the price at $4.7bn. Its cost needs to come down substantially, by reducing the spacecraft’s capabilities and possibly getting the European Space Agency to contribute more, the review says.
But the Planetary Society, a leading lobby group for space science, fears that there will be no mission beyond Mars. “This is not just the loss of an American flagship mission, it is a loss to planet Earth,” says Louis Friedman, the society’s former director.
Making scents: how foxes mark territory
Thirty years of data about the movement of urban foxes has led to a new mathematical model of animal territories – which could have applications well beyond behavioural ecology.
The study at Bristol University models the complex system of individual-level interactions that determine animals’ transient territorial boundaries.
The size of a territory depends on how long the fox can exert its control before intruders cross the boundaries into its space. This involves a trade-off between two factors: the time required for a fox to move between its own boundaries and the period during which it can maintain its scent trail within the territory.
When a disease called sarcoptic mange killed most of Bristol’s foxes in the 1990s, Professor Stephen Harris noticed that as the animals in one territory died, their healthy neighbours moved in and took over within three or four days. He assumed that this was because the scent marks of the original owners were no longer fresh.
The study, published in PLoS Computational Biology, shows how important it is for a fox to renew its scent marks, further demonstrating the transient nature of territories, and contradicting the belief that scent marks serve as a longer-term indicator of boundaries.
Lead author Luca Giuggioli says the model may also “shed light on the processes responsible for the formation of territorial boundaries in early human hunter-gatherer societies, and eventually help predict how the size of modern-day countries will evolve.”
His colleague Jonathan Potts adds: “Our theoretical framework might also inspire designs in collective robotics. From very simple rules, the individuals divide space into territories, and if one individual should fail, its territory is taken over,” he says. “Building an army of territorial robots that move according to these rules could be an efficient and robust way to deal with dangerous tasks over a wide spatial area, such as clearing minefields.”
Were humanity’s first steps in the Kalahari?
The idea that modern humans originated in Africa and then migrated out to Asia and Europe more than 60,000 years ago has been conventional scientific wisdom for decades. It has been less clear where in Africa Homo sapiens first evolved from earlier hominid species.
Most palaeontologists have assumed that our ancestors originated in east Africa, on the basis of fossil and archaeological evidence, but the largest genomic analysis of the continent’s hunter-gatherer populations carried out so far strongly suggests the region of origin was actually southern Africa.
That conclusion emerges from a study published in Proceedings of the National Academy of Sciences of genetic variation in 27 African populations, including all the continent’s remaining hunter-gatherer groups.
The international team led by Marcus Feldman of Stanford University looked for changes in 650,000 chemical “letters”’ of the genetic code. They found that the “click-speaking” bushmen of the Kalahari desert in southern Africa had substantially more genetic variation than other groups including the “click-speaking” hunter-gatherer peoples of east Africa, the Hadza and Sandawe in Tanzania.
The genetic diversity of the bushmen – greater than any other group on earth in relation to their numbers – is a strong indicator that they are the closest representatives alive today of the source population from which all modern humans evolved.
Why your mother’s diet sets you up for life
Some people have long argued that you are what you eat – and a group of scientists has now provided a new twist that suggests you are also significantly what your mother ate, writes Andrew Jack. Researchers at Cambridge University showed that pregnant female rats which were malnourished by restricting their protein intake gave birth to offspring more likely to develop type 2 diabetes.
The findings, published in Proceedings of the National Academy of Sciences, demonstrated that the gene Hnf4a, already known to play an important role in the development of the pancreas and the production of insulin, was regulated by maternal diet, exacerbating modifications to DNA.
“It is remarkable that maternal diet can mark our genes so they remember events in very early life,” said Miguel Constancia, senior co-author on the paper. Jeremy Pearson, associate medical director at the British Heart Foundation, which jointly funded the study, said: “A mother’s diet may sometimes alter the control of certain genes in her unborn child. It’s no reason for expectant mothers to be unduly worried. This research doesn’t change our advice that pregnant women should try to eat a healthy, balanced diet.”
Of course the study was conducted in rats, so there are questions about how far the same effect would be translated into humans. But if mother already knows best, she now knows a little bit more about precisely why eating sensibly makes sense.
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