快猫短视频

THE next Mars landing will be worth making time to watch. It may be the last of its kind.

Scheduled to touch down on the Red Planet on 5 August via a nail-bitingly intricate, autonomous procedure, NASA鈥檚 Curiosity rover will undertake an unprecedented two-year hunt for signs of alien life. Costing $2.5 billion, Curiosity 鈥� known formally as the Mars Science Laboratory (MSL) 鈥� is the biggest, boldest, most expensive Mars mission ever attempted.

It is also the last of a dying breed. Fresh austerity at NASA, combined with a host of nations with new, spacefaring ambitions and a nascent commercial space industry, mean that Mars exploration post-Curiosity looks set to become smaller-scale, more innovative and a lot more international. 鈥淚t鈥檚 looking like MSL is going to be a one-of-a-kind rover,鈥� says Ryan Anderson, a member of the Curiosity team.

The moment may be bittersweet for NASA, but the shift should bring big rewards for humanity鈥檚 exploration of Mars and beyond, and comes at an opportune time. Previous Mars missions had to cast a wide net because scientists weren鈥檛 sure what they would find. But after almost 50 years of sending robots to Mars (see diagram), it is now possible to ask more targeted questions. The next robots will not have to retake NASA鈥檚 baby steps. 鈥淭hey can start doing new things right away,鈥� says mission scientist John Grotzinger. Different countries will also have varied objectives and focus on different regions or periods of Mars鈥檚 history, providing a more complete picture.

Take the European Space Agency鈥檚 ExoMars project, due to launch an orbiter in 2016 and a rover in 2018. Earlier this year, NASA pulled out as a mission partner, but ESA is moving ahead with new support from the Russian Federal Space Agency. ExoMars will drill 2 metres into the surface to see if life could have had a toehold on Mars up to 3 billion years ago. The mission complements NASA鈥檚. Mars rovers Spirit and Opportunity covered swathes of the Martian surface in the search for water, for example, while Curiosity will use its built-in chemistry lab, including X-ray scanner and mast-mounted laser, to analyse the composition of rocks and look for organic molecules. These could indicate evidence for ancient or even current life.

Even countries with fledgling Mars programmes, which may not initially break new scientific ground, can offer early rewards for space exploration. The Indian space agency recently announced a plan to launch its first Mars orbiter in November 2013. Project director Mylswamy Annadurai declined to offer more details, but even adding another orbiter will ease communication with landers on the Martian surface, including Curiosity and whatever comes next, says .

China and Russia have Mars plans too. Both were hit hard by what some call Russia鈥檚 鈥淢ars jinx鈥�. The country has lost 16 spacecraft en route to Mars 鈥� most recently the Phobos-Grunt probe mission, which was also carrying China鈥檚 first Mars satellite. It eventually fell back to Earth after its rockets failed to propel it beyond low Earth orbit in November last year.

However, the mission was ingenious and highlights the benefits of diversity. The probe was bound for Mars鈥檚 moon, Phobos, which has mostly been spurned in favour of its glamorous parent planet. ESA鈥檚 plans beyond ExoMars include bringing back dust from Phobos to answer questions like whether or not the moon is a captured asteroid, what it is made of and how it compares with other moons in the solar system. 鈥淭here鈥檚 bona fide science to be undertaken on Phobos,鈥� says ExoMars project scientist Jorge Vago.

Also with eyes on the Mars prize are commercial ventures. SpaceX of Hawthorne, California, which recently made history by docking the first privately built spacecraft with the International Space Station, is redesigning the Dragon capsule it sent to the ISS to land on Mars. Founder Elon Musk says he hopes to send a spacecraft to Mars in 12 to 15 years. 鈥淲e can actually land anywhere in the solar system, which is pretty cool,鈥� he told 快猫短视频. While NASA plans to send humans to Mars, its plans don鈥檛 involve landing (see 鈥�What about humans?鈥�). By contrast, Musk鈥檚 main interest in Mars is human colonisation.

Still, NASA, with its unparalleled Mars successes, is far from out of the game. The agency鈥檚 MAVEN orbiter is set to launch in 2013 to study the Martian atmosphere. And a small lander called InSight will soon be proposed to study the planet鈥檚 interior by recording vibrations on its surface. In June, US scientists and engineers met to draw up a post-budget-cuts road map for Mars exploration.

Meanwhile, a fleet of cheaper, highly specialised prototype rovers is being built in labs around the US. Some, like a rover called LEMUR, can climb steep slopes and dangle from grippers to explore underground lava tubes. Protected from harsh surface conditions, these caves may be the best place to look directly for preserved signs of life on Mars. Others, like a proposed rover called SMALER, could be built in large numbers to scout for the best sites from which samples could be brought back to Earth. Such sample-return missions have a number of advantages: the same samples can be examined repeatedly with ever-improving technology, and some tests, like determining precisely how old the rocks are, can currently be done only on Earth.

All the more reason to hope Curiosity鈥檚 landing is smooth. Its destination is Gale crater, probably an ancient lake bed, which hosts a 5-kilometre-high mound thought to have recorded most eras of Martian history. To get there, Curiosity will dangle from a hovering deployment craft and touch down wheels-first in a manoeuvre involving an unproven system called the Sky Crane (see image).

Tensions are high. If the rover crashes, NASA and others might turn away from Mars altogether. 鈥淚f it fails, it will be a disaster,鈥� Vago says. 鈥淲e all rely on each other鈥檚 steps and discoveries. We really are putting all our hopes on MSL doing well.鈥� Curiosity team member Ken Edgett agrees: 鈥淎 lot hangs on the Sky Crane.鈥�

If it works, it will be a triumph that could breathe new life into NASA鈥檚 Mars programme and offer a taste of a more focussed future. 鈥淢SL is the first mission where we鈥檙e less in Star Trek mode,鈥� says mission scientist Ashwin Vasavada. 鈥淲e have a real idea of what we鈥檙e doing and why we鈥檙e going there.鈥�

鈥淭his is the first mission where we鈥檙e less in Star Trek mode. We have a real idea of what we鈥檙e doing鈥�