A lot of good questions and comments have been given regarding the thickenss of Europan Ice and how to penetrate it.
Here are some ideas researchers could take to determine ice thickness. (Maybe this is not a new idea.) When we were first interested in going to the Moon and the idea of impact craters covering to moon was still gaining acceptance, a lot of researchers began using high velocity projectiles aimed at various materials to see what happend during crater formation. Did anyone ever try ice as a target? Ice as cold as on Europa? Is there a way to strucure an icy target with varying thicknesses to see what size of projectiles and velocities are required to penetrate an icy layer on Europa of varying thicknesses? Does it necessarily follow that comparing craters on the tree Jovian satellites will produce linear results as far as ice depth is concerned? Maybe ice on Europa is different due to underlying temperatures, or density. Ganymede is bigger, with more gravity and perhaps denser ice, less gravitation stretching from jovian/satllite tides and therefore colder, perhaps less fractured and "harder" than Europan ice. Callisto is colder, formed under cooler conditions seems to have more rocky composition. It too could be harder, denser ice than Europa. We have talked about sending impactors to Mars and sent two which may or may not have deployed, The intent was to have the imactor penetrate up to a meter in rock or rocky soil. How far into ice could we exoect a similar probe to go? It also appears, to me, a novice, that every method to penetrate great distances in the ice will tend to concentrate silicates (rock) ahead of the melting device as the freeed particles in the freshly melted icy will tend to follow the probe through the ice and either wedging it in place or blocking its vertical movement. What methods or designs are needed to avoid this from happening? Mickey Schmidt -----Original Message----- From: Thomas Green [mailto:[EMAIL PROTECTED]] Sent: Thursday, May 30, 2002 12:58 PM To: [EMAIL PROTECTED] Subject: Re: Europa's ice thickness It seems like pressure is just one problem to solve. Some other questions I'm thinking about: 1. How long would it take to melt through 12 miles of ice? 2. Is communication much more difficult? 3. Are there layers of ice flowing at different speeds that might make for a shear-zone or something? 4. Do the odds of finding obstructions increase, like layers of debris from meteorite ejecta? Seems like the best bet is to map the ice and look for thinner areas, or even better, and upwelling zone. Otherwise, we'd need one heck of an RTG, which probably isn't pocket change. Maybe IceClipper or some other precursor mission could sample the ice below a few meters and try to detect anything interesting. That seems like our best near term hope of finding out what the oceans may contain. Just a radical thought: instead of melting or mechanical drilling the ice, how about evaporating it through electrolysis? The hydrogen and oxygen produced could be captured and used as a secondary fuel source to maybe power a small heater? I guess the immediate problem is the exhaust from burning it would refreeze into ice, but it could be vented behind the probe as it descends? Cheers, Tom [EMAIL PROTECTED] wrote: > Is that assuming 12 miles of water? Does it change things if you're under 12 > miles of ice, whose density is less than 1 g/cc ? > I'm not smart enough to figure that out... > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Reeve, > Jack W. > Sent: Thursday, May 30, 2002 11:46 AM > To: [EMAIL PROTECTED] > Cc: [EMAIL PROTECTED] > Subject: RE: Europa's ice thickness > > With Europa's 0.135 Earth gravity, and assuming the same 1.022 SG seawater > density, excluding all other small variables, real pressure at 12 miles > depth on Europa is equivalent to an Earth ocean depth of about 8550 feet, or > 3790 Earth PSI, or around 23.8 Earth mPa. > > Jack > == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/ == You are subscribed to the Europa Icepick mailing list: [EMAIL PROTECTED] Project information and list (un)subscribe info: http://klx.com/europa/
