Search found 102 matches
- Fri Mar 05, 2010 11:47 pm
- Forum: General
- Topic: Jones: No Warming For 15 Years
- Replies: 72
- Views: 25141
- Fri Mar 05, 2010 12:17 pm
- Forum: News
- Topic: Polywell FOIA
- Replies: 475
- Views: 187376
The first three questions can be answered with 99% certainty without an experiment, i.e. cheap and quick, because they are based on best-case assumptions and well-understood physical processes. The fourth one is a computational grand challenge, and even with massive theoretical effort, you are like...
- Thu Mar 04, 2010 11:56 am
- Forum: General
- Topic: There Was Once a Lot More CO2 In The air
- Replies: 40
- Views: 12553
- Thu Mar 04, 2010 10:30 am
- Forum: News
- Topic: Water on the moon
- Replies: 23
- Views: 9506
- Thu Mar 04, 2010 8:32 am
- Forum: News
- Topic: Water on the moon
- Replies: 23
- Views: 9506
Capturing an asteroid of worthwhile size will take decidedly non-trivial power-plant and drives. However, as a very large number of asteroids are available within Jupiter's orbit (and don't forget the Trojans), they're close enough that fusion powered ships might be able to do the trip without worry...
- Wed Mar 03, 2010 12:44 pm
- Forum: News
- Topic: Water on the moon
- Replies: 23
- Views: 9506
- Wed Mar 03, 2010 12:00 pm
- Forum: News
- Topic: Water on the moon
- Replies: 23
- Views: 9506
Take a closer look. That's GW, not MW. Even more power :). 120MW won't get you anywhere all that fast (though it will get you far if you are very patient, so long as you're already in orbit). However, even with only 120MW, no need to collect space icebergs: that much power should do a nice job of Lu...
Giorgio: Please read this (and the rest of the site). You might like the liquid droplet radiators :) What it boils down to is that unless you have no other option (admittedly, our current situation), thermal energy production in space just doesn't make sense. You lose too much energy to Carnot. That...
One of the most useful things about a pBj Polywell is that the waste heat can be rejected at high temperatures. And secondly it is not a thermal machine. So on the generation side it is not limited by Carnot. There are of course other problems. Yeah, and the biggest one is shielding for the side-re...
- Wed Mar 03, 2010 11:16 am
- Forum: News
- Topic: Water on the moon
- Replies: 23
- Views: 9506
One perfectly good use for the oxygen: reaction mass. At the same specific impulse in an ion engine, oxygen (single electron removal) requires 1/16th the current as hydrogen to produce the same thrust, though the drive voltage will need to be 16 times that of hydrogen. (603kA, 187kV vs 9.6MA, 11.7kV...
- Tue Mar 02, 2010 1:01 pm
- Forum: General
- Topic: Earth's magnetic reversals, and risks..
- Replies: 31
- Views: 9371
Well, not having the link handy (dig through the general forum archives, it's in one of the AGW threads), I tried some googling and found this. It seems it may not have been one killer asteroid, but two, along with volcanoes spurred on by the second.
- Tue Mar 02, 2010 12:24 pm
- Forum: General
- Topic: Earth's magnetic reversals, and risks..
- Replies: 31
- Views: 9371
The dinosaurs were done in by external events (asteroid). Their demise is rather irrelevant. Scientific hypotesis range from asteroid to vulcanic activity. For what I know up to today there is no relevant proof for one or the other. I read recently that it actually was proven (crater found, even). ...
- Tue Mar 02, 2010 11:03 am
- Forum: General
- Topic: Earth's magnetic reversals, and risks..
- Replies: 31
- Views: 9371
In addition, the last reversal was about 780000 years ago: long after our ancestors evolved. Also, the flip seems to take 100s-1000s of years. (info from wikipedia.
I think asteroids are a much bigger worry.
I think asteroids are a much bigger worry.
- Tue Mar 02, 2010 10:34 am
- Forum: General
- Topic: Earth's magnetic reversals, and risks..
- Replies: 31
- Views: 9371
The dinosaurs were done in by external events (asteroid). Their demise is rather irrelevant. Successful is as simple as "can breed fast enough for its population to grow". Back to cosmic rays: first, it seems I was wrong about "solar cosmic rays". I have to agree, it's a horrible name. As for the ra...
- Mon Mar 01, 2010 1:06 pm
- Forum: General
- Topic: Earth's magnetic reversals, and risks..
- Replies: 31
- Views: 9371
It's not just a misnomer, they don't exist. Cosmic rays, by definition, come from outside the solar system (thus "cosmic"). In which case, I guess the magnetic field does protect us from solar cosmic rays, along with the hard vacuum of space. However, see below for a more serious treatment. The magn...