By the way, regarding some of the suggestions being floated around by this
group's members: the current plan is to indeed give the Cryobot some ability
to veer slowly to the side to avoid obstacles detected by radar and/or sonar
below it, using several different jets of hot water (NOT steam) pumped down
through different spots spaced around the nose. (Pumped jets of hot water
have also turned out to be far more efficient at melting through ice than
simply heating the Cryobot's metal nose is; they're now part of the standard
design.)
Isn't it funny, that we've somehow stumbled across the same answers to our dilemma, and we're not getting paid 6 figures a year for it?
Also, there will have to be some peripheral small jets of hot
water on the Cryobot's sides to keep the meltwater layer from refreezing
around them before the Cryobot has slid all the way down through.
Yes. I'm thinking the following: what we're shooting for is for our little torpedo to grease its way through the borehole. This can be accomplished by 2 things:
1) spray teflon on the sides of the model. It's cheap, and the damned stuff will work. And, it's heat resistant.
2) we need to have the sides wet, in a sense, floating the model in a layer of its own meltwater as it slides down and along. I suspect that the model should therefore have a jet in its nose, and 4 jets in its tail. A jet at the nose bores a small hole. The 4 jets at the rear propel the model, and through gravity, provide water to the sides. The water doesn't have to be hot, just warmer than the ice.
If the rear jets can be timed correctly, the entire model may have a spin imparted to it, which will reduce friction even more, and assist the model to literally drill its way through the ice... I'm thinking that we can stamp spiraled grooves deeply into the sides of the model, and attach a heavy bit to the front.
Consider: any ice field on Earth, or on Europa, is liable to have rocks and boulders (or asteroids, in the case of Europa) scattered throughout like raisins in pudding. This model has got to move, therefore... and, it's got to be able to kick past gravel... so a drill shaped exterior may be a necessity.
I did some more thinking about the 'steam issue'. I agree, steam is not necessary, considering that if/when this thing gets ice frozen over it, it will generate hydraulic pressure. So, the model has got to be very sturdy, and very streamlined.
Speed is not the issue, and too much heat would possibly be counterproductive, as the model might hit a rock, stop, and then be so damned hot that a cavity is created around it before it can get around the rock, thereby stranding the model in a water bubble under 50' of ice.
It's got to move, but it's got to move SLOW. Temperature of the model should probably be about 30 degrees faranheit warmer than the ice.
As for those radio transponders, J. Michael Parenti is right: the plan is to
have each one, on release from the Cryobot's rear, automatically extend
several spring-loaded prongs to anchor itself to the walls of the ice tunnel
(which is bound to freeze solid again just a fraction of a meter behind the
Cryobot). But they will have to be very low frequency to transmit through
ice -- so LF that I doubt they're available commercially.
We don't need the world. We just need some animal transponders, such as they attach to the ears of wildlife. There have got to be some radio hobbyists out there who can tell us how to make them low frequency.
Although a standard transponder would probably work in 100-200' of ice, such as we are likely to work with, we also would like to demonstrate workability on Europa... so we should shoot for as close to the real demands as possible.
Spring-prong anchors.... hmm... I was thinking that if they were shot or rocketed into the slush at the rear, that the slush itself would be enough anchor, particularly if they were roped to one another:
0------0------0------0---------//-----{======>
Here, the // marks represent a slush and ice core refreezing behind the model.
Can the transponders relay a signal? Would it help if they were wired together with a thin filament?
A pity the Icepick site doesn't have a file vault to store files sent to it
by the readers: I'd love to read out and store that IEEE Aerospace piece by
Zimmerman et al, which is an extremely detailed and up to date description
of how NASA's own Cryobot design is evolving. See his JPL Technical Paper,
though, as a partial substitute.
Talk to Gail and Hibai about that. We REALLY need a file vault for technical proposals. I'd also love to see your Europa websites list become part of the Icepick website, as a sort of 'library' category.
-- John Harlow Byrne
