The Space Thread

NASA can be good for ego and flashiness so Trump might support it with money, after all I'm sure he'd like to build the Trump Space Tower.

I suppose it would be darkly hilarious if he could basically stake a claim on the moon the way Gingrich blathered on about all those years ago.

Trump cancels Space Elevator: not enough gold leaf.

edited 13th Nov '16 10:25:18 PM by SabresEdge

I think the problem with NASA is kind of like the problem with roads. Everyone likes them in general but they hate to pay for it.

Pretty much. With any luck someone will tell him about the Chinese moon rovers though and he'll decide we need to win the new space race, or something.

That's the main thing I'm hoping for from him.

Are there asterisms that comprise of only four stars?

Depending on who you ask, Crux. See for example the Australian Flag (including Epsilon Crucis) vs the New Zealand Flag (no Epsilon Crucis) and it's Alpha through Delta that technically define the asterism, Epsilon just hangs off to the side of the cross.

Also Triangulum and Triangulum Australe are both constellations with their primary asterism defined by only three stars each

Why does Venus not have a magnetic field if it has a molten core?

Presumably because it does not have convection there.

Why doesn't it have convection?

Venus is just weird — from its weirdass rotation (counter-clockwise, over 200 of our days long — in fact, Venus has a longer day than it has a year), the oddly dense crust and the insanely dense atmosphere... Somewhere in all that, convection, magnetism and plate tectonics died in infancy. :/

Instead, Venus probably lets heat out of the core by occasionally going totally molten from crust-to-core in a very long cycle. The first instance of the cook-off probably ended whatever life could have tried to form waaaaaay back when the place sort-of resembled both Mars and First!Earth of the time. Before the Moon and the Late Heavy Bombardment.

Having said that, there is some evidence that Venus could have had a moon like ours, once... gained in the same way. Unfortunately, it got whacked with yet another small planet, and its moon probably also slammed back down. These events in (for the solar system) quick succession likely caused the rotation to go retrograde (and to slow down as a result) like it did. Any life that could've survived that (unlikely) would have died in the first theorised cook-off, later.

edited 21st Dec '16 1:37:16 AM by Euodiachloris

Would the atmosphere of Venus make up for the lack of magnetic field in terms of radiation protection?

As long as you're deep enough in it, sure. I'm not actually sure if the altitude that's a comfortable temperature/pressure for humans is "deep enough", though. Not that it matters all that much; if you're talking about human habitation (which is the main concern regarding radiation levels), then the sulfuric acid is a more immediate concern.

Yeah, by the time you're down far enough in the atmosphere to stop worrying about the sun's rays, radiation is the least of your problems.

I think the main concern for offworld habitation is higher energy particles than what the sun gives off. Such as gamma rays and the possible occurrence of a nearby supernova.

That is one reason why they are talking about em field generators for space ships, since em fields can deflect those.

What about the radiation surrounding Jupiter?

... What radiation surrounding Jupiter? All I know is that Jupiter has a huge-ass powerful magnetic field that can and did rip apart wayward objects that were in the wrong place within its general vicinity at the wrong time, and is in fact responsible for one of its moons (Io) being plagued by literally global-wide volcanic activity 24/7.

edited 21st Dec '16 12:55:09 PM by MarqFJA

Ain't nuthin' that can stop gamma rays except good ol' mass. The only thing that an electromagnetic field deflects is charged particles, while gamma rays are a type of electromagnetic radiation.

Jupiter has enormous radiation belts, consisting of charged particles held in place by its powerful magnetosphere. It's similar to Earth's Van Allen belts, except several thousand times stronger (and thus nasty enough that you have to think about it when you're talking about spacecraft expected to travel through them). You're half-right regarding Jupiter grabbing things and tearing them to shreds — that happens, but it's a property of tidal forces created by Jupiter's gravity well, not it's magnetic field.

... Man, scifi writers who do anything involving human habitations with Jupiter's vicinity (whether on its moons or near the planet itself) seriously need to be given crash courses on this subject. Hell, I never knew of Earth's Van Allen belts before one or two years ago, so even the writers who delve into outer space within Earth's vicinity need such a course!

edited 21st Dec '16 3:27:36 PM by MarqFJA

Radio communication between satellite or orbital stations around Jupiter would be a total nightmare.

Which you rarely find in fiction that has these things. At most, you'll read about downtime as a station gets occluded by the big, bad Jupiter itself. Never "dammit, charged particles be thick today — better switch everything off and head to the bunker!".

edited 21st Dec '16 10:46:46 PM by Euodiachloris

Occasionally I think about the plausibility of building a ring habitat around Venus, but then I come here and think "Well, that would be a constant struggle to upkeep" because sulfuric acid kind of sounds constantly corrosive.

On a slightly related note, is there an advantage to putting a telescope on the moon as opposed a satellite that is a telescope?

No atmosphere, but if you have to travel thorough space anyway, placing it in space, where it has greater freedom of movement and accessibility seems just as good.

If built on the far side of the moon a radio telescope 'd get a pretty solid shield from earth's mess of signals.

There's also some arguments to be made for ease of scaling things up; something like aricebo would be much easier to build on the moon (pick a suitable crater, smooth out/ sculpt it's surface, coat in concrete that could likely be made from regolith one site fairly easily, construct receiving tower at dish focal point) than in space (build dish in segments groundside all of which would then need to be launched to orbit and then assembled); you'd still be talking a major project either way but getting it done on the moon seems more feasible.

On the other hand, the supply lines from the Earth to orbit are much easier than those from Earth to the Moon. I suppose some key questions would be how much infrastructure you already have in orbit, and if you have ready access to a moonbase or not.

Repairs would be a pain,what with the constant rain of tiny material.