Will the people proposing to use a chemical reaction to melt the ice (e.g., thermite/thermate/magnesium, etc.) please explain how this will be an environmentally friendlier alternative to keeping a hole open with kerosene (or your favorite antifreeze) and using a surface generator and a power cable to the cryobot? I cannot believe these are 100% efficient reactions that will leave no residue to contaminate the ice. Also, if using either approach, the meltwater will dilute the chemical or antifreeze and will have to be pumped away. I believe Bruce mentioned this problem earlier.
Gary
PS. Recall what happened when they used thermite to raise the space ship out of the ice in The Thing (original movie version)? Always expect the unexpected!
At 03:58 PM 11/2/2002 -1000, you wrote:
Gail, et al.,
The energy calculation should include the max. volume for the batteries, their energy density or output in amp-hours at a given voltage (say 12 volts) per unit volume, quantity of water to melt and stay melted (the effective volume around the bot times the pathway length), energy to melt a given volume of ice, projected decent rate or experiment duration in hours. Bear in mind that batteries to not work (discharge) very well near zero degrees C. That's why we keep them cold for long-term storage, to minimize self-discharge rates.
You could try non-rechargeable lithium. They are the highest energy density batteries at the present time, which approach 3X over Pb-acid motorcycle batteries. Other candidates are Ni-Cd (high energy discharge rate; rechargeable), Ni-metal hydride, Li ion (both are rechargeable) and silver-zinc (high energy discharge rate; rechargeable). The Navy uses the latter type for torpedos. They can be expensive and are hard to find.
Probably best to get the maximum battery connection at the same voltage and let them work together as one giant battery discharging.
Gary
At 04:33 PM 11/2/2002 -0800, you wrote:
The original concept proposed motorcycle batteries for the power source, primarily, I think, because of their small size. How long would they continue providing enough current to melt the ice enough for the vehicle to sink?
We've been talking about 500' of ice (or variously 100' or even 20' of ice frozen in a vertical culvert), so the question is whether 3 batteries would last long enough for a significant penetration?
Is there a way to conserve the energy by hooking up some sort of thermostat so that the drain on the batteries wouldn't be continuous? Or hooking them up in sequence so that only one battery at a time would be providing current, i.e., as one battery is drained, the next one takes over?
I think this is pretty important if we are to propose a completely self contained unit that is not dependent on electrical current from the surface. I think the calculations would be pretty straightforward and relatively simple. I'd do it, but I only have ten fingers and ten toes.
How about it? I really think this is pretty basic to our design.
Gail
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