Scientists at NASA's Jet Propulsion Laboratory in Southern California have been asked to design the ultimate all terrain vehicle, something that can operate billions of miles from Earth at temperatures of around 300 degrees below zero, and be able to fly like an aircraft, roll along the ground like an ATV, and cruise across an ocean like a boat.
So they borrowed from the past, and looked to the future, and came up with kind of a flying swamp buggy that dates back to the beginning of aeronautical engineering. It's a blimp.
Later this month, the wizards of Pasadena hope to begin testing a scaled down model of a blimp that could give us a close-up look at one of the most mystifying and intriguing objects in the solar system, Saturn's largest moon, Titan.
Titan is no small body. With a diameter of 3,200 miles, it's bigger than the planet Mercury. We don't know a whole lot about what it's really like, because it is enshrouded in a dense atmosphere that makes it almost impossible to see the surface. But what we've seen so far has left planetary scientists screaming for more.
Floating Over Gas Oceans
Images from the powerful Keck Telescope in Hawaii penetrated the atmosphere just enough to show dark and light areas on Titan's surface. There's a good chance the dark blotches are oceans of liquid hydrocarbons, most likely methane or ethane.
We'll get a better feel for the place in January of 2005, when the Hugens probe is released by the Cassini spacecraft and plunges into the atmosphere of Titan. Cassini, launched in 1997, is speeding toward Saturn and is expected to give us our best look yet at the ringed planet and its moons.
One person who will be watching that encounter with a great deal of interest is Jack Jones, a mechanical engineer in JPL's advanced projects group, who is leading the research effort to find out if a blimp would really work on Titan. The idea has some appeal, Jones says, because a blimp would be so versatile.
"The scientists want to explore the atmosphere, and both the solid surfaces and the liquid oceans. They want to land on both of them and explore," Jones says.
They will do that remotely, of course. There won't be anybody aboard this blimp. It would inflate just as it reaches Titan's atmosphere, and drift around the moon at about six miles altitude during its shake-down cruise. Scientists would use its cameras and instruments to identify areas they want to take a closer look at, and eventually the blimp would use electric-powered propellers to drive it down to the surface and guide it to the desired locations.
The harsh conditions at Titan could make it ideally suited for a blimp, Jones says.
Working at Minus 300
"It's very cold on Titan," he says, and that could work to the advantage of the blimp. A colder climate means a denser atmosphere, and since a blimp — which is actually just a powered balloon — has to displace atmosphere to remain aloft, it works more efficiently in a dense atmosphere.