As space fans anticipate news of organic molecules from the Mars Curiosity rover – cryptically teased by the mission’s chief scientist, John Grotzinger, – there’s one man who is even more excited than most.

Former NASA researcher Gilbert Levin says that a positive sign of organics by Curiosity would confirm his claim that NASA has already seen evidence for life on Mars – from an experiment called Labeled Release that went to the Red Planet aboard the Viking mission.

If Curiosity has found evidence for organics, as many are hoping, “that removes the last barrier to my interpretation of the Labeled Release results, and leaves us free and clear”, Levin told ��è����Ƶ.

Though the prospect of new Curiosity findings have set the internet abuzz, nobody from NASA has yet said publicly what they are: Grotzinger has refused to elaborate, pointing ��è����Ƶ, and other journalists, to a presentation scheduled for the American Geophysical Union annual meeting in San Francisco, which begins on 3 December.

‘History books’

Grotzinger’s key comment to US National Public Radio – “this data is going to be one for the history books. It’s looking really good” – concerned an instrument called SAM, for sample analysis at Mars, which, among other things, is tasked with finding organic molecules in the Martian soil.

Ordinarily, finding organics on the surface would not count as evidence for life, nor would it be surprising, since . But in the case of Mars, it’s more complicated, says Levin.

That’s because the failure to detect any organics at all by an instrument aboard the Viking lander was the counter-evidence that cancelled out an apparent detection of active biology by Levin’s Labeled Release experiment. That experiment showed that radioactively labelled carbon from a nutrient solution added to the soil was released into the air in the test chamber – an apparent sign of metabolism.

Though Levin has long argued otherwise, the consensus has been that Viking did not find evidence of life on Mars.

Caution urged

Levin acknowledges that, after more than three decades of argument over what the Viking results really mean, opinions are not likely to change overnight, no matter what the new Curiosity results may show. Although proving the presence of organics in the soil will “remove all rationale against” his interpretation, he says, “it’s hard to change a paradigm”. Most scientists are convinced that Viking’s results were inconclusive. “I doubt this will change the consensus” he adds.

of the NASA Ames Research Center in Moffett Field, California, is a leading researcher on the possibility of life on Mars, and he, too, urges caution. “This is probably not as exciting as the internet rumors suggest,” he says – as someone who is privy to what Curiosity has found.

Then again, McKay was never convinced that Viking failed to find organics. He has argued, , that the Viking non-detection of organics was invalid, by demonstrating that soils from the Atacama desert in Chile, known to contain organics, showed no signs of them in a test that replicated the one on Viking.

A “gravity tractor” could deflect an Earth-threatening asteroid if it was deployed when the asteroid was more than one orbit away from the potential impact, according to a new study. If the space rock was found heading straight for Earth, a combination of techniques – including a gravity tractor – might save the day.

The study, carried out by NASA’s Jet Propulsion Laboratory in Pasadena, California, shows that the weak gravitational pull of a nearby spacecraft could deflect a hypothetical asteroid 140 metres across, big enough to cause regional devastation if it hit Earth.

“Prior to this study, the gravity tractor deflection technique had been proven in only a conceptual way,” says Clark Chapman of the Southwest Research Institute in Boulder, Colorado, who was not involved in the study.

“Although there were few, if any, substantive criticisms of these concepts, some of us had the feeling that the ideas were viewed as quaint but not-ready-for-prime-time,” he says. “The JPL study gives it the solid engineering underpinnings that we never really doubted, but now are there for anyone to see.”

Exactly how much of a push is needed to deflect an asteroid depends on how long before a potential impact the intervention begins, and what kind of orbit the object is going to follow in the interval, says Rusty Schweickart, a former Apollo astronaut and chairman of the , which funded the study.

Narrow keyhole

In some cases, the asteroid will pass through a narrow “keyhole” in space before returning on a future orbit to hit Earth. If it misses the keyhole, which may be only a few hundred metres across, it will go on to miss Earth.

That’s where a gravity tractor alone could do the job. “The gravity tractor is a wimp, but it’s a precise wimp,” Schweickart told ��è����Ƶ. “It can make very small, precise changes in orbit, and that’s what you need to avoid a keyhole.”

The well-known asteroid Apophis could pass through such a keyhole in 2029, leading to an impact with Earth just seven years later.

In the JPL study, the imagined asteroid is initially discovered on a direct path to impact, so a gravity tractor would be too feeble to deflect it alone. Instead, the team envisages a one-two punch.

Gentle force

First a spacecraft would be crashed directly into it, similar to the Deep Impact mission that impacted a comet in 2005. That would provide a much greater change of direction, but in a less controllable fashion. There’s a chance it could even push the path of the asteroid into one of those dangerous keyholes.

Then a second spacecraft, the gravity tractor, would come into play. Weighing around a tonne and hovering about 150 metres away from the asteroid, it would exert a gentle gravitational force, changing the asteroid’s velocity by only 0.22 microns per second each day. But over a long enough time, that could steer it away from the keyhole.

In the simulation, a simple control system kept the spacecraft in position, and a transponder on the asteroid helped monitor its position and thus determine its trajectory more precisely than would be possible otherwise.

The simulated asteroid was 140 metres wide and its elongated shape was copied from an asteroid called Itokawa, which was visited by Japan’s Hayabusa spacecraft in 2005.

Like real asteroids, it was spinning in the study – important since asymmetric gravitational effects could push the tractor out of position. “We didn’t want some nice easy, smooth shape,” says Schweickart. “We have a little bitty spacecraft with this monster swinging its butt at it.”

A preliminary on the simulation was presented by JPL’s Don Yeomans at the recent Asteroids, Comets and Meteors meeting in Baltimore, Maryland.

Comets and Asteroids – Learn more about the threat to human civilisation in our .

A new analysis of a canyon in the US state of Idaho lends support to the idea that Mars, which boasts similar canyons, had substantial rainfall and major floods early in its history.

Idaho’s Box Canyon resembles a snake, with a sinuous body and a rounded head (see image at right). One theory suggests that such “amphitheater-headed” canyons form slowly, as seeping groundwater gradually erodes canyon walls in the snake’s head.

That process might create some canyons in softer rock, say researchers led by Michael Lamb of the University of California, Berkeley, US. But they say such slow seepage could not have transported the metre-sized boulders that were carried downstream in Box Canyon, which is carved into harder basaltic bedrock.

“It requires a lot of water to remove them,” Lamb says.

In fact, it would have required a megaflood – a catastrophic outpouring of massive amounts of water in a relatively short period. Such megafloods occurred numerous times in the western US several tens of thousands of years ago and played a significant role in shaping the landscape.

The discharges are thought to have resulted when structures that held large lakes in place – such as rockfalls or glaciers – eroded or melted away, releasing the lakes’ water in a sudden flood.

Basalt forms much of Mars’s surface. If similar Martian canyons were carved in solid basaltic bedrock as well, they “would have required a release of some large body of water”, Lamb says.

That implies a substantial rainfall cycle, he told ��è����Ƶ, since that is the best explanation for how water filled such a lake in the first place.

If, on the other hand, such canyons formed from seeping groundwater, “that allowed the hypothesis that there could never have been any rainfall on Mars,” Lamb says.

Lamb says such a scenario is unlikely but not impossible – orbital images are not sharp enough to tell for sure if these canyons are carved in solid basalt, as opposed to “softer” basalt that has been weathered into sand-sized particles.

But tongue-shaped flows resembling fresh lava surfaces do suggest that some canyons were carved in solid rock. “There’s compelling evidence that most of the surface is intact lava flows,” Lamb says.

Journal reference:

Mars – Mars is full of surprises, learn more in our continually updated .

Video: Watch an animation of the Lynx Mark I as it prepares for and undertakes a mission to the edge of space

A sleek craft that may be the first “sports car” of commercial spaceflight was unveiled on Wednesday, in Mojave, California, US. It is designed to be able to travel to the edge of space and back several times a day.

While Virgin Galactic’s SpaceShipTwo will carry eight people, making it more of a space minivan, the Lynx Mark I is only a two-seater and smaller than a private jet.

US Company revealed its plans for the new rocket plane at the company’s headquarters, on the edge of the tarmac of the US’s first certified private spaceport. SpaceShipTwo is under development just next door.

Xcor say Lynx Mark I will start flights two years from now. Funding from the Air Vehicles Directorate of the US Air Force Research Laboratory and additional sources not yet revealed will help develop the craft in time. Xcor says that 50 test flights starting in 2010 over a period of six months should be enough to ready Lynx Mark I for commercial operations.

The Ansari X Prize-winning SpaceShipOne and its successor SpaceShipTwo both need to be carried to high altitude beneath a specialized carrier airplane.

Taste of space

The Lynx, however, will take off and land from long airport runways, using its own rocket engines for power from the taxiway all the way to an altitude of 61 km. Unlike the US space shuttle, which glides to a landing without engine power, the Lynx will be able to abort a landing by switching its rockets back on ready for another attempt.

Lynx is fueled by kerosene – the standard fuel of jet aircraft – mixed with liquid oxygen. The relatively simple-to-handle fuel and oxidiser combination should help to give the craft a rapid turnaround time, says company president Jeffrey Greason.

“Our company’s goal has always been to build rocket-powered vehicles that can be flown and operated like regular aircraft,” he says. Lynx is even relatively environmentally friendly: “They are fully reusable, burn cleanly, and release fewer particulates than solid fuel or hybrid rocket motors,” Greason says.

The two-seater can carry aloft either one passenger – seated next to the pilot – or a scientific or commercial payload. The whole flight will last about 25 minutes, providing a brief taste of weightlessness and the view of the jet-black, star-filled sky above the blue Earth. It is an experience that some surveys indicate thousands of people may be willing to pay hefty sums for.

Xcor will not sell tickets directly, but will license sale of the 25-minute flights to existing space-adventure tourism companies, Greason says. The company has not yet revealed the price tag for flights aboard Lynx.

‘Solid achievements’

Charles Lurio, Boston-based writer and editor of The Lurio Report, a private newsletter that analyzes the developing commercial space industry, says the company has been carefully assembling the necessary technical capabilities.

“From the start, Xcor has been committed to closely matching their available funding to solid, step-by-step achievements that lead to the next market or the next funding source,” he told ��è����Ƶ. “The Lynx is another step in that pattern – and on its foundation, there is a direct road to truly low-cost, reliable human access to orbit.”

The cost is expected to be a fraction of that of currently available rocket flights for research, potentially opening up new possibilities for research in space by university and small-business customers, Greason says. The company already has an agreement with one private research lab that plans to fly multiple flights each year.

Xcor, which set the current record for point-to-point distance in a rocket-powered plane with its “EZ Rocket,” has already begun flight-testing the rocket engines planned for Lynx Mark I, mounted on a different craft.

The company is also already planning its Lynx Mark II, which will fly nearly twice as high and provide a longer space experience.

Dramatic features of the Martian landscape that appear to have experienced catastrophic flooding may have been covered over by lava flows, new research suggests. This could make it much harder for future landing missions to analyse the evidence for past water on the Red Planet.

The finding is one of several new reports resulting from more than three months of high-resolution surveys by the new Mars Reconnaissance Orbiter spacecraft, which went into orbit around the planet in March 2006.

Among the areas examined in detail is a valley system called Athabasca Valles, which has long been interpreted as having been carved out by sudden, catastrophic flooding. The new images show the entire region seems to be covered by a few metres of lava.

Team member Alfred McEwen of the University of Arizona in Tucson, US, still thinks the valley system was created by flowing water. But he says future robotic missions to Mars will probably not be able to investigate the water’s effects on the surface there.

Other MRO observations also suggest it will be difficult to interpret the role water has played on the surface of Mars. For example, the planet’s extremely flat northern plains, interpreted by many as the remaining basin of an ancient ocean, does not seem to be covered by a deep layer of fine sediments as some had thought.

Instead, it is strewn by large boulders that according to one theoretical model should have been buried under layers of sediment long ago if the ocean had been deep, long-lived and turbulent.

Buried clues

But McEwen says that model might be wrong and that it is still possible that an ocean covered the region. “There are lots of other concepts of Mars oceans and how they formed,” he told ��è����Ƶ. “Who knows how much evidence of oceans is buried under lava?”

Maria Zuber at MIT in Cambridge, US, says there is still “plenty of evidence” that water played a role in the planet’s past and that large quantities of it remain in the poles and frozen in the ground. The new observations just suggest that in some places, “whatever was there has been covered up by volcanism”, she told ��è����Ƶ.

Lava has previously thwarted scientists trying to study Gusev crater, where the rover Spirit landed in January 2004. Although all the evidence gathered from orbital images suggested Gusev had been an ancient lake, filled by water from channels seen entering the crater, the lander found mostly just beds of lava, which may overlie earlier lake deposits.

Meanwhile, Zuber and her colleagues were able to use the MRO data to determine that the planet’s southern polar ice cap contains the largest reservoir of surface water in the inner solar system outside of Earth.

Mars – The Red Planet is full of surprises; learn more in our continually updated .

Journal reference: (vol 317, p 1706, 1709, 1711, 1715, 1718)