Wednesday, February 1, 2012

One Per Cent - Drone could soar through Titan's skies for years

David Shiga, reporter
5614747283_a69485b3a0_b.jpg(Image: Mike Malaska)

Titan's surface is a Bizarro World version of Earth: lakes full of liquid methane, mountains made of water-ice, and rippling dunes made of solid benzene. Now a specially-designed unmanned aerial vehicle (UAV) could help scientists unlock the secrets of the enigmatic Saturnian moon without breaking the budget.

The idea gets a boost from the physics of flying, says a team led by Jason Barnes of the University of Idaho in a new study in Experimental Astronomy.

Titan has less gravity than Earth, so a UAV would weigh just 1/7 as much there as it does on our planet. And its atmosphere has 4 times the density of Earth's, which would also help keep a winged vehicle aloft.

As a result, flying is 28 times more efficient on Titan and means that the same aircraft could shoulder 28 times more weight than on Earth, the team says. (It has even been suggested that a human could become airborne on Titan by flapping strap-on wings, the team notes, though no one has been able to test the idea, unfortunately.)

They have designed a UAV to explore Titan, which they call AVIATR (Aerial Vehicle for In-situ and Airborne Titan Reconnaissance). Powered by a radioactive power source, AVIATR would weigh 116 kilograms and could fly through Titan's skies for a year, the team says.

It would map the moon's surface and clouds, sense raindrops striking the UAV's skin, and measure winds. Travelling at 6 metres per second, it could cover 1000 kilometres in just two days, allowing it to explore lakes at Titan's poles, dunes at the equator and everything in between.

The Titan airplane would provide better manoeuvrability and require less power than the balloons that have previously been proposed for Titan. The airplane would complement other proposed Titan missions like a boat for exploration of the moon's lakes, the team says.

Of course there are challenges. UAVs on Earth have never flown for more than a few days continuously without landing, for example.

And the lightweight power source that AVIATR needs, called an Advanced Stirling Radioisotope Generator (ASRG), has yet to be flown on a space mission. However, simpler radioactive power sources are used on Cassini and other spacecraft.

But perhaps the biggest challenge will be finding funding for the mission in this era of tight US budgets. AVIATR's price tag is a cool $750 million. By the standards of outer solar system flagship missions, though, that's a bargain - the Cassini and its associated Huygens lander cost $3.26 billion.

If AVIATR can overcome all these hurdles and get to Titan, the coolest part would come at the end of the mission, when the team proposes sending the UAV in for a soft landing on one of Titan's dunes. It would get a very close up view this way, but its power source might stop working because of the lack of airflow to cool it.

That will probably be the most fun anyone has on Titan - robot or human - until sandboarding really takes off there.

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