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Sea Gliders for Other Worlds
An anonymous submitter writes: "NASA has, for the moment, killed funding for research leading to an underwater probe for Europa's suspected saltwater ocean. But it's possible that this is a good thing. SPACE.com proposes that U.S. Navy-funded research into underwater gliders could offer a superior means of probing Europa, exploring Venus, and even diving into the methane/ethane seas of Titan. NASA wanted a big battery and propeller machine under the ice of Europa, but that might break down, stir up water that should left undisturbed, and leak lubricants into a pristine research environment. The navy wants gliders with internal actuators because they have no flaps or propellers, no lubricant, and one already exists that could "fly" under the Pacific from Seattle to Tokyo on a penlight battery! Another model uses no batteries for locomotion at all, but instead taps heat gradients."
Electromagnetic drives to move a vessle in water proved to be to high a challenge to fund. While we are still working on effecencies, the current weight to thrust ratio is that of a model rocket engine pushing an adult's mountain bike. The technology is improving, but with funding this low, we spend a lot more time at our desks then we do in the labs.
These things kick ass. I'm a grad student at UW in Oceanography--the pink seagliders in the second picture are built two floors below where I am typing. They're amazing--they communicate home with a cellphone antenna, and there's a 386 laptop connected to a phone line down the hall that accepts their dial-up connections. This allows them to upload their data and recieve new instructions for their mission. Currently they just have a conventional phone on-board for testing, but that will hopefully be upgraded to something like the remains of the Iridium network for the real version.
They are the result of an amazing confluence of technologies--low-power cpus, which turn on something like once every five minutes to check their situation and take a measurement, temperature and salinity probes that give reliable data without calibration for a year, battery packs, cellular communication, GPS. The great application for these, however, is not to other worlds--it's to our own. In a few years, it is hoped that there will be a global array of automated seagliders and buoys taking temperature, salinity and velocity measurements everywhere in the ocean. Basically, it will be used to construct a global climate monitoring system--something we'd never be able to do without low-power computers and sattellite tech.
Actually, the book "2010" (1982) didn't contain the part about "Use them together, use them in peace."
That was added in the movie (1984), along with the armed conflict between the USA and the Soviet Union in Central America.
For some reason, Peter Hyam cut out the part about the Chinese ship "Tsien" that did land on Europa, and added the political aspect.
He must have been smoking some good crack if he thought that was an improvement on the book.
The only way to get a satellite there is a nuclear power source - the amount of energy from the sun that reaches Europa is very low (hence, all of our deep-space stuff has had a radio-thermal power source). The problem with the nuclear power sources 'melting' (actually, at the temp/pres. on the surface of Europa, water will sublime) has been studied. As I recall, the approximate depth of entry is on the order of tens of meters (worst case, more or less) after a catestrophic containment failure on the surface. The ice shell on Europa is predicted to be between 1-10km thick, so there's no real contamination problem there. That's actually one of the nice things about the NASA design - with the umbilical cord, your power source could remain on the ice surface (with your transmitter), and not risk contaminating the postulated oceans below, not to mention the fact that your datalink between the swimmer and the transmitter is nice and easy. The real problem with working on Europa is the harsh EM environment (particularly for the vehicle traveling there). The EM fields from Jupiter at that distance are extreme, and will give you a mission life on the order of a month or so (starting from the time you're in orbit, and remember you've got to melt/dig/whatever your way through a kilometer or more of ice)...