Comet or Saturn moon next NASA target

WASHINGTON • NASA’s newest mission will either land a quadcopter-like spacecraft on the surface of Saturn’s moon Titan or collect a sample from the nucleus of a comet.

The two proposals were selected from a group of 12 submitted to the New Frontiers program, which supports mid-level planetary science missions.

The first, called Dragonfly, would be an unprecedented project to send a flying robot to an alien moon. Equipped with instruments capable of identifying large organic molecules, the quadcopter would be able to fly to multiple locations hundreds of kilometres apart to study the landscape on Titan. This large, cold moon of Saturn features a thick atmosphere and lakes and rivers of liquid methane, and scientists believe that a watery ocean may lurk beneath its frozen crust.

Titan is one of the best hopes for alien life in the solar system because it is the only body, aside from Earth, with liquid oceans and lakes.

It’s “an environment that we know has the ingredients for life,” said lead investigator Elizabeth Turtle, a researcher at Johns Hopkins University’s Applied Physics Laboratory. With Dragonfly, “we can evaluate how far prebiotic chemistry has progressed.”

Although they are made of methane rather than water, the moon is covered in rich organic material that is undergoing chemical processes that might be similar to those on early Earth, before life developed. A discovery made earlier this year also found that Titan holds special molecules that could form cells and allow organisms to survive the perishingly cold temperatures of minus 179 degrees.

It will be only the second time that a craft has landed on Titan. In 2004, NASA’s Huygens probe touched down, but it was not equipped to look for signs of life. The launch is currently scheduled for 2025, with the probe touching down in 2034.

The Comet Astrobiology Exploration SAmple Return, or CAESAR, mission would circle back to the comet 67P/ Churyumov-Gerasimenko, which was visited by the European Space Agency’s Rosetta spacecraft from 2014 to 2016. After rendezvousing with the Mount Fuji-size space rock, CAESAR would suck up a sample from its surface and send it back to Earth, where it would arrive in November 2038.

NASA has sampled a comet before; the Stardust mission collected dust from a comet’s gassy outer envelope, called its “coma.” But this would be the first mission to return material from a comet’s icy surface.

“Comets are among the most scientifically important objects in the solar system, but they’re also among the most poorly understood,” said Cornell University researcher Steve Squyres.

The missions now enter a concept study phase, when the scientists involved can further develop their proposals. A final selection will be made in July 2019.