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Comment Re:Velcro? (Score 1) 18 18

YEs, you are mistaken. The velcro was supposed to be limited to small patches with some separation as to prevent fire from propagating from one patch to the next if it caught fire. But it was so useful that they more-or-less carpeted the interior with it.

      Teflon was implicated in the initiation of the fire, since it cold-flows and can cause shorts, and start the fire. Once it gets going, particularly in nearly 17 psia pure oxygen (vice the in-flight 5 psia), the velcro practically explodes.

      Had the same fire started in-flight there was a remote possibility that they could have vented the cabin and put it out, and maybe survived, but the high pressure on the ground, not a chance, even aluminum can burn in those circumstances and the only reason it didn't was because the capsule burst from over-pressure before it got going.

Comment Re:CUBEsat? (Score 2) 22 22

That's a pretty minor distinction. I was an industry advisor for what might have been the first 3-high cubesat. The only important restriction is that it fit in the ejection canister.

      The basic single 4.5" cubical satellite is *very limited* in capability due to lack of any viable attitude control and very low power available. It's tough to do anything useful even in low Earth orbit. That would be crippling for an interplanetary mission.

      I expect someone may have worked out the numbers, but for a Mars relay you have more-or-less no attitude control and need a fair bit of power for at least several hours. It's going to take a pretty big battery+an decent array to run rad-hard electronics for any length of time. None of this "guts of a FRS radio" telemetry stuff, that will fry very quickly beyond the Van Allen belts. Also, no or inconsequential albedo heating, so it will need big heaters to keep going for any length of time.


Comment Re:If it sounds too good to be true (Score 5, Informative) 243 243

And there's math behind it, too. To raise the volts, you have to lower the amps. It'll work until it can't provide enough current for the device that it's powering.

      If it holds a constant 1.5V output the current draw from the device will also remain constant. What *will* happens is that as the battery terminal voltage (input to the boost converter) drops, the current drawn from the battery will go up, not down. It effectively turns the load into a constant power device.
      I am skeptical about the life-saving claims. Alkaline battery-power devices are typically expected to operate down to about 1V terminal voltage. Since the primary effect of discharging is ion depletion, the internal resistance of the battery is what is changing, meaning by the time you get to doubling the current at low states of charge, you will be depleting it much faster. So the time of use will fall off a cliff very abruptly at the end.

Comment Re:I don't understand.. (Score 2) 221 221

I had a similar idea about Zeppelins. Hydrogen is dangerous, Helium is expensive, so why not just pull a vacuum in the lift cells? Empty space is much lighter than helium, just think of the buoyancy! Everybody is an idiot, except for me.

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