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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."
Well once you've got your own luxury submarine this would be a good toy to take along with you beneath the waves.
air and light and time and space
Even if the device is hermetically sealed, it seems that contamination can't be avoided. For example, the little pump would have lubricants in it. No matter how the thing is sealed, eventually water will get in and the lubricants will get out. Even a solid glass sphere won't last forever. What the difference between contaminating Europe today, or doing it a million years from now? The point is to avoid contamination, right?
If tits were wings it'd be flying around.
But will it probe Uranus?
BH
Fools! They laughed at me at the Sorbonne...!
First of this is incredible technology. Low-impact approachs to exploration are absolutely what we need to avoid screwing up other planets as we have with this planet. Its always bothered me that we trash on Mars... but anyway, one comment in the article struck me as odd:
On Venus or Europa, that process is somewhat reversed. [...]
"A reversed gradient is nothing I would be too concerned about [...]"
So, if there is a reverse gradient, then doesn't that also mean that there is going to be extrordinary convection currents as the heated (and less dense) material rises to the surface. While there logically would also have to be a down current, the mediums would have to be really turbulent.
So, in order to heat up the machine to obtain energy to move actuators, one would have to deal with the turblence (in order to get to the heat source). I wonder if batteries are need in some way...
Now the real question is, how do we get these things off of the planet (or safely disposed of) once they are done being used.
I think this is a question that needs to be addressed more often (low-impact exploration). Who knows what kind of effect our stuff could have on other forms of life. If there were batteries, they would eventually have to leak and then there's battery acid polluting an environment.
The reason this low-impact is important is because it means we can do _more_ exploration without having to worry about the effects.
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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.
I knew a Navy engineer who wanted to make a gliding torpedo. It would be slow, but so quiet that it would be undetectable. He also thought that it could be programmed to hold a ship 'hostage', poised just beneath it and set to detonate if the ship changed position. Don't know if anything ever became of his ideas, but they were interesting.
It's all well and good to go on long missions under the Europa ice crust, but if this is expected to be of any use to science, there must be a way of getting data back to Earth. I doubt we could equip this thing with a radio powerful enough to send data through potentially miles of water and ice. The original plan for the battery+propeller vehicle was to have it tethered, IIRC. Would this work in the same way? The cooler thing to do would be to let it go free but then returh and report to a base station (or maybe interface with a cable hanging down from the base station into the water.) The base station could then relay the data back to and orbiter and then on to Earth. Anyway, I think this could be the real technological challenge. Even if you can move far on a "penlight battery" you can't send much of a signal with one.
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.
As I've always said, it seems the best long-term defense against terrorism is for the US to play fair with the rest of the world. Until we do, we're all at risk.
A glider in water has an option that a glider in the air doesn't: it can alternate between being heavier and lighter than the fluid around it.
Suppose this glider had a buoyancy tank which could be expanded or contracted like a fish's swim bladder. Whether rising or falling, it can trade altitude for horizontal motion.
It wouldn't be fast, but it probably doesn't need to be.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."