NASA's Far-Out Space Concepts Written 13 January 2017

Panelists: Moderator Alvin Yew, program manager, NASA Innovative Advanced Concepts; Geoffrey Landis, scientist, NASA's Glenn Research Center; Mason Peck, associate professor, Cornell University; Jonathan Sauder, technologist, NASA's Jet Propulsion Laboratory

by Ben IannottaAerospace America Editor-in-Chief

Panelists discuss "NASA Innovative Advanced Concepts (NIAC): Enabling Missions from Venus to Alpha Centauri," Jan. 12 at the 2017 AIAA SciTech Forum, in Grapevine, Texas.

Imagine a rover on the surface of Venus, propelled by the slow movement of the planet's thick atmosphere; or a submarine exploring the depths of a hydrocarbon lake on Saturn's moon Titan; or maybe a lander hopping from site to site on Neptune's moon Triton; or how about a gram-sized spacecraft accelerating to 160 million kph and whizzing past an intriguing planet discovered in the solar system closest to ours.

NASA sets aside a small fraction of its $19 billion annual budget to fund studies of radical-sounding concepts like these, which panelists discussed Jan. 12 during the "NASA Innovative Advanced Concepts: Enabling Missions From Venus to Alpha Centauri" panel at the 2017 AIAA SciTech Forum in Grapevine, Texas.

Mason Peck, a Cornell University associate professor involved with the NIAC-supported interstellar Breakthrough Starshot Project, said NIAC is extremely valuable for those with big but high-risk visions.

"There's at least some source that will think your idea appealing," he said.

He and the Breakthrough team are trying to figure out how to squeeze a spacecraft's critical elements, especially a communications package, onto what looks like a computer chip. They'll then accelerate this toward Proxima b, a recently discovered planet more than 4 light years away, by focusing laser light onto a sail.

The big question: "Can you make something small enough that also survives? We're talking about a 1 gram satellite," Peck said.

Another question is whether engineers should attempt to include a camera to send back at least a rudimentary photo of the planet, probably via optical communications. The difficulty is that the spacecraft would streak by Proxima b with only a short opportunity for a single, true-color photograph, Peck said. That's because the spacecraft would be closing so fast that the wavelengths from the planet would be shifted to the blue spectrum. As it speeds away, the wavelengths would be shifted to the red.

It might be better to send a spectrometer, he said.

Closer to home, there is the second planet from our sun. "Venus is a fascinating planet," said Jonathan Sauder of the NASA-funded Jet Propulsion Laboratory. He wants to figure out how to navigate a rover across its surface despite pressures that would crush a nuclear submarine and temperatures that would melt lead.

At Venus' average temperature of 462 degrees Celsius, even electronics built to U.S. military specifications could not survive, because they're designed for a maximum of 125 C.

"The longest we've been able to have an object survive on Venus is two hours," he said.

So, game over? Not quite. Sauder has been studying how to make a rover operate almost entirely mechanically. On the top of the rover would be a turbine through which Venus' slow-moving, thick atmosphere would flow and propel the rover.

Venus is famous for its heat, but the solar system also has icy worlds, including Saturn's giant moon Titan and Neptune's moon Triton. Geoffrey Landis of NASA's Glenn Research Center has been studying how those might be explored.

Titan has hydrocarbon lakes on its surface, and Landis wants to put a submarine into one of them. He said, "Titan is the only place in the solar system, other than Earth, that has liquid on the surface," even if the liquid is methane and ethane. True, Jupiter's moon Europa is intriguing because it is thought to have a saltwater ocean under its icy shell, but the ice might be many meters thick, he noted.

To get the submarine to the surface, Landis would borrow the entry vehicle design from the U.S. Air Force X-37B spacecraft. Radio waves traverse hydrocarbons very well, so unlike in Earth's saltwater, the craft would not necessarily have to surface to communicate.

For exploring Triton, Landis wants to land a "hopper" spacecraft on the surface that would explore one area and then spring to another. It would be about as tall as a person and weigh 500 kilograms.

"It's not bad," he said. "It's something we can send to Triton."


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