Each year NASA's Innovative Advanced Concepts (NIAC) programme asks researchers to submit ideas for space technology that could prove useful in the next few decades. Last year selections included two-dimensional spacecraft and suspended animation.
This time NIAC has chosen 12 projects, each of which will receive $100,000 for a nine-month study, with the possibility of another $500,000 for further research if the idea checks out.
The scheme lets researchers dream up missions to places we have never been before. "The hydrocarbon lakes on Titan are unique in the solar system," says Steven Oleson of NASA's Glenn Research Center in Cleveland, Ohio, who is leading a proposal for an autonomous submarine to explore their depths.
"Besides Earth, there are really no other exposed liquids." Some hope that life may have taken root in and around those lakes, though it would be nothing like life on Earth.
In 2011 NASA considered sending a boat called the Titan Mare Explorer to that moon, but the mission was passed over for funding in favour of the upcoming Mars InSight probe. Oleson is hopeful that Titan Mare will one day go ahead, and thinks a submarine would be the next logical step. The two probes could even be sent together in a joint mission, he says. "If you only explored our ocean with a boat, you'd miss out on a heck of a lot of stuff."
Submarines on Earth have to come to the surface to communicate because radio waves don't penetrate very far though water, but that may not be an issue on Titan. "The really neat thing is that the hydrocarbons should be transparent to radio waves," says Oleson, meaning the sub could beam data up to an orbiting relay satellite without a break in exploration.
Oleson team's plans to use the NIAC money to explore this and other ideas, such as using the liquid hydrocarbons for fuel, for a mission that could take place in the 2040s.
Another funded proposal is a sealed Martian greenhouse designed to test whether or not the Red Planet can support life and be terraformed. One end of the lander bores into the ground, taking a core of Martian soil inside before sealing itself off. The top of the craft, which pokes out of the ground, contains a transparent dome to let sunlight in. Inside, bacteria from Earth that can survive extreme conditions would be released into the soil core and attempt to survive in their new home. The mission aims to determine whether such life can take hold on Mars.
Another proposal takes inspiration from the European Space Agency's Rosetta mission, which will harpoon a comet later this year and ride it around the sun. The new proposal imagines a spacecraft which grabs a comet and then reels itself out while simultaneously applying regenerative braking, gaining energy in the process. This would let a small spacecraft fly quickly to the far reaches of the solar system without the need for extra fuel.
It is claimed that such a craft could reach Pluto in just five-and-a-half years, compared with the nine-year journey of NASA's New Horizons mission, which is due to arrive at the dwarf planet next year.
Jacob Aron, New Scientist
Image: NASA - Sending a submarine to Titan’s largest northern sea, Kraken Mare