快猫短视频

IT WAS only , but it takes us a step closer to finding out if there is life on Mars.

On 27 April, private spaceflight company SpaceX used Twitter to announce its intention to send its Dragon capsule to the Red Planet as soon as 2018 鈥� and it seems like it may actually happen. The timeline has been labelled ambitious, but realistic.

The Red Dragon mission is step one in CEO Elon Musk鈥檚 even more ambitious plan to send people to live on Mars. If Red Dragon flies, it may become the quickest way to deliver experiments to search for life on the Martian surface 鈥� or even bring a piece of Mars back to Earth. NASA is already in talks with SpaceX to send such an experiment to the planet should this mission be a success.

鈥淓verything about Dragon since the beginning has been done with Mars in mind, you can tell from the design,鈥� says Jim Bell of Arizona State University in Tempe, who has worked on several NASA missions to Mars, including the planned Mars 2020 rover.

鈥淓verything SpaceX has done since the beginning has been done with Mars in mind鈥�

Details of SpaceX鈥檚 plan are scarce at the moment, although Musk is expected to reveal more in September at the International Astronautical Conference in Guadalajara, Mexico. The overall plan has been in motion since at least 2011, says Brian Glass at NASA Ames Research Center in California.

鈥淭his is not out of the blue,鈥� Glass says. 鈥淚t鈥檚 not just boom, two years off the block. This is more like a seven-year effort that culminates with launch in 2018 and goes from there.鈥�

SpaceX鈥檚 Falcon 9 rocket first launched in 2010 and its Dragon capsule has been ferrying cargo to the International Space Station since 2012. The trip to Mars will use souped-up versions of both: the Falcon Heavy rocket, which is essentially three stages of the Falcon 9 rocket strapped together, and the Dragon 2 capsule, which will eventually transport astronauts to and from the ISS.

鈥淚f the Falcon Heavy stays on schedule and the Dragon 2 stays on schedule, they can make 2018,鈥� says former NASA chief technologist Robert Braun, now at the Georgia Institute of Technology in Atlanta.

Neither piece of kit has been extensively tested yet. The first Falcon Heavy launch is scheduled for later this year, and Dragon 2 is set to undergo test flights this year and next year.

The tough part won鈥檛 be getting the spacecraft to Mars, but getting it down to the surface (see 鈥�Red Planet鈥檚 curse鈥�). With its thin atmosphere and strong gravity, Mars is a difficult place to land. At 900 kilograms, NASA鈥檚 Curiosity rover pushed the mass limit for what parachutes can carry to the surface, and its daring hovercraft landing in 2012 was called 鈥渟even minutes of terror鈥�.

Dragon 2 will weigh in at about 6400 kilograms, more than seven times heavier. It will be equipped with eight engines that will allow it to hover. They were tested when the capsule was dangling from a crane in January (see photo, far right). That鈥檚 鈥渒ey for Mars landing鈥�, SpaceX tweeted on 27 April. It will probably use a combination of parachutes and retrorockets to reach the surface, but even so it鈥檚 no easy feat.

鈥淪paceX wouldn鈥檛 [make this announcement] unless they had a reasonable approach to entry, descent and landing,鈥� says space policy expert John Logsdon of George Washington University.

It will also have the most experienced Mars lander in the business on its side: NASA. The space agency is partnering with SpaceX on the Mars mission, offering its deep space communications network and expertise in exchange for access to SpaceX鈥檚 data.

So once Red Dragon arrives at Mars, what will it do? SpaceX鈥檚 private funding puts it in a position to send any experiment Musk fancies 鈥� although it is bound by international planetary protection requirements to shield anything that might live on Mars from destruction by incoming spacecraft.

鈥淭he 2018 flight is a demonstrator,鈥� Glass says. 鈥淚t鈥檚 their ride and their rocket. There鈥檚 no commitment on their part to fly anything at all, not even a wheel of cheese, on these flights.鈥�

The launch date is also too soon to build a custom experiment, but SpaceX could bring in an off-the-shelf experiment if it chooses.

But the firm is in preliminary discussions with Glass and colleagues to include an instrument called Mars Icebreaker Life on future Red Dragon missions, possibly as early as 2020. This would land at the icy north pole, near the Mars Phoenix lander site. Phoenix, which was equipped with a drill, was the first Mars mission to taste water ice, but couldn鈥檛 search for life directly.

Icebreaker would have a drill that can reach at least 1 metre below the surface, and three different instruments that would 鈥渟earch for specific biomolecules that would be conclusive evidence of life鈥�, the team wrote in a 2012 paper.

鈥淚cebreaker is different in that it is looking for components for extant life,鈥� Glass says.

That would be a departure in itself. Since the Viking mission in the 1970s, NASA has shied away from searching for life directly, opting instead to show that environments would have been habitable if life had happened to take hold. Astrobiology budgets have also been shrinking over the past 15 years.

鈥淚n my view the Mars programme (and the Mars science community) has been reluctant to embrace life detection,鈥� says Chris McKay, also at NASA Ames. 鈥淪paceX may be interested in life detection if not as a pure science question then as an astronaut health and safety issue.鈥�

Future SpaceX missions could even send a chunk of Mars back to Earth. The return of Martian samples has been a top priority for years, and some consider it the only reliable way to test rocks for signs of life.

Earlier this year, a study by Andrew Gonzales and Carol Stoker at NASA Ames showed that Red Dragon would be able to carry equipment to launch a recovered sample towards Earth without the need to rendezvous in Mars orbit with another spacecraft (Acta Astronautica, ).

鈥淭he competition isn鈥檛 between NASA and SpaceX 鈥� it鈥檚 between humans and Mars鈥�

That would make sample return simpler and cheaper than previous mission designs, they say. If the Mars 2020 rover collects rocks and stores them for future pickup by a Red Dragon mission, it could become simpler still.

The alliance between SpaceX and NASA on Red Dragon may signal a more collaborative phase in space exploration just as ambitions to go to Mars seemed to be waning. We are no longer in a space race world, Logsdon says. 鈥淭here鈥檚 really not a geopolitical question for which the answer is, 鈥榞o to Mars鈥�,鈥� he says.

NASA鈥檚 budget is unstable 鈥� the same day that SpaceX made its announcement, funding for a balloon-like aerobraking system the agency was designing for Mars was cut. But as the old guard, NASA still has the most experience. Combining that know-how with the commercial sector鈥檚 energy and flexibility makes sense.

鈥淭he competition should not be between SpaceX and NASA,鈥� says Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics. 鈥淚t鈥檚 between humans and Mars.鈥�

鈥淚 think the idea of NASA working with them is a precursor to how we鈥檙e going to be exploring in the future,鈥� agrees Logsdon. 鈥淲hen we go to Mars, it鈥檚 going to be a partnership between multiple countries, and between government and industry. Here鈥檚 one early instance of that.鈥�

This article appeared in print under the headline 鈥淗unt for life on Mars鈥�