OriginalArlen writes: NASA's first attempt to test Orion parachutes didn't go so well. "The result was a landing that severely damaged the test mock-up." (A type of landing also known as 'lithobraking'.) The parachutes, which would be used to safely land the Orion crew capsule in the event of a launch abort after an escape rocket pulls the capsule clear of the booster, failed to open after a drogue earlier in the sequence failed to open properly. A NASA spokesperson pointed out that this was the most complex test of it's type since the '60s, with a total of 18 parachutes involved. (The footage is on YouTube as well.)
Whilst sea-ice obviously doesn't raise the sea level when it melts, a similar runaway feedback that lead to significant reductions in the Greenland or Antarctica ice sheets would cause a 6-7m sea-level rise, indisputably catastrophic for human society as well as the polar bears.
OriginalArlen writes: Universe Today has a fascinating article discussing the difficulty of executing EDL (entry, descent, landing) on Mars for vehicles bigger than MER, Viking and Pathfinder, and for manned craft in particular. Airbags can't be used for obvious reasons, but the atmosphere is too thin to be used for parachutes or aerobraking by large heavy vehicles, and the stronger gravity (compared to the moon) makes an Apollo-style powered descent impossible. The best current idea is a huge inflatable torus called a hypercone.
Nevertheless it would be interesting to see reasoned responses from the community who believe this is not merely possible, but inevitable — and even, as Hawking has said, vital for the survival of the species. So, who's right — Hawking or Stross?
OriginalArlen writes: RealClimate has an enjoyable piece by Figen Mekik breaking down a few commonly held misconceptions about climate. Apparently ice, water, and water vapour have the same chemical formula! (Who knew?) But are you sure you know the real relationship between global warming and the ozone layer — or why summers are warmer than winters?