The Space Thread

Welp, Space X does it again, this time landing a first stage at sea. Heh, looks like Elon Musk is having a good week

Have we found asteroid fields other than ours yet?

I do believe there have been some IR signatures that are believed to associated with fairly extensive asteroid or comet fields, especially around some younger stars but I can't give any specific examples I'm afraid.

Plus there's whatever is going on with this star.

Thanks

New question: Has anything in all three systems making up Orion's Belt been found yet?

The next steps in the commercial space race

I have been a fan of astronomy since I was six years old.

I'm disappointed in you Venus. You're almost the same size. You've got an atmosphere. You're close enough for liquid water. You're the closest planet to us. But were you habitable? Noooo', you just had to be a blasted wasteland. What a bitch

Actually, Venus would probably be the easiest planet for humans to colonize — we'd just need to stay high up in the atmosphere instead of on ground level. The surface is a crushing, burning corrosive hellscape, but there's a layer of the atmosphere where the temperature and pressure are both near Earth-normal. Of course, it's still filled with sulfuric acid, but that just means you don't go outside without an environment suit (which is true basically everywhere that's not Earth). The best part is, since the atmosphere is so friggen dense, you wouldn't even need any kind of powered flight in order to hang out at the right altitude — just make sure your habitat has the right density and it will float, like a helium balloon on Earth. (You could actually literally fill parts of it with helium if you wanted, in order to offset the higher density of structural members and the like.)

Giant flying blimp-cities on Venus? It's more likely than you think.

Cloud City here we come.

If the layer of atmosphere is the same density as earth, then you don't get the buoyancy bonus of dense atmosphere up that high. This reminds me of that time I attempted to learn if one could live on the "surface" of Jupiter. Except at the depth where the pressure is 1 atm, The gravity is already double, I think, earth's gravity.

It is too bad sulfric acid corrodes just about near anything.

edited 21st Apr '16 9:43:46 AM by war877

You still get the "buoyancy bonus" because you'd be floating on the denser atmosphere that's below you. Stuff floats in other stuff that's equal density. If you want something to float at one atmosphere's worth of pressure, then its total density needs to match that level — which would mean using lighter-than-air gasses to offset the heavier-than-air stuff the habitat is made out of. So like I said, basically a giant blimp.

And there are plenty of things that are resistant to sulfuric acid, like PTFE — aka teflon. To survive in the atmosphere of Venus, you need a nonstick coating.

Science is awesome.

edited 21st Apr '16 10:40:47 AM by NativeJovian

What makes Venus easier then mars?

Which while a cold rock, has almost no destructive events to worry about, allowing easy habitats?

An almost lack of an atmosphere and low insolation are issues.

Your going to need a suit either way, and wouldn't not atmosphere be easier to work with then a destructive one?

Well, in the short term, Mars is probably easier, because living on Mars is basically the same as living in space, only with more gravity. We're already pretty good at living in space, so in some ways there are fewer unknowns about living on Mars.

In the long term, however, Venus is a better prospect for a variety of reasons. The fact that it's got a thick atmosphere means it's already providing three things vital to human life that Mars is utterly lacking: comfortable temperature, comfortable pressure, and radiation shielding. It's also got stronger gravity than Mars (about 90% of Earth's, compared to less than 40% for Mars). You'd still need protective equipment to walk around "outside" on Venus, but it's sort of like the difference between a wetsuit and a spacesuit. An environmental suit designed for Venus would need to be airtight, but it wouldn't need to be vacuum sealed, or temperature regulated, or include protection against radiation, all of which means it could be a lot cheaper as well as easier to move and work in.

This is assuming that you're staying at a comfortable altitude, naturally. Higher up you'd need more and more protection until eventually you're in space again and need a full spacesuit. Lower down and you get higher temperatures and higher pressures, and you'd eventually need something like an atmospheric diving suit, which are hard-skinned suits that protect divers from extreme pressures by basically being a miniature, person-shaped submarine.

But yeah. Mars: almost no atmosphere, no appreciable radiation protection, low gravity. Venus: atmosphere of a comfortable temperature and pressure at the right altitude, which also provides radiation shielding, and comfortable gravity. The downside of Mars is that you'd basically have to build a spaceship on the planet itself (with all the attendant risks) to live there. The downside of Venus is that you have to deal with the corrosive atmosphere and the fact that you can't get too close to the surface without running into a whole new set of problems. Ultimately, these problems can all be engineered away... except for Mars's low gravity, where Venus is preferable and always will be. At least until someone invents Artificial Gravity, and then we don't need to worry about planets at all anymore.

edited 21st Apr '16 3:46:07 PM by NativeJovian

Finally someone who agrees with me!

Venus also has a crapton of natural resources (natural gas). We could probably build a real life Cloud City there.

Pluto continues to not be as boring as I thought. Also, talk says that they're finally planning a visit to Europa. I've waited so goddamn long for even an alien microbe, I want some confirmation that the rest of existence isn't a barren wasteland already.

Didn't they detect fossil evidence of extraterrestrial microbes on some meteorites?

It is fairly questionable whether these "fossils" are actually of biotic origin.

So they weren't definite, then? A pity. I was hoping it would prove at least the existence of simple microbes outside our planet.

http://mic.com/articles/141470/hubble-just-spotted-an-enormous-bubble-in-space?utm_source=policymicTBLR&utm_medium=future&utm_campaign=social#.SIO9Kwb6F

Space bubbles!

Sorry I had to

Sometimes I like to think what would happen if the Moon pulled a Gurren Lagann and fell to the Earth. OK: thought exercise. The Moon suddenly stops moving and decides to fall to Earth. How long would it take? And when it finally lands, how long will it take before the entire Earth is rendered a wasteland?

If the moon somehow lost all its orbital energy at once, it would start falling toward Earth exactly like any other dropped object — meaning it would start accelerating toward Earth (actually, the Earth and the moon would start moving toward each other, as the moon's gravitational pull on Earth is nontrivial). The actual amount of time it would take gets gets into some pretty heavy math that I'm honestly not up for doing (like, "not confident in my ability to do correctly", not just "too lazy to do"), because as they get closer together, they speed up because the stronger pull of gravity between them.

What would happen once it hit would be a pretty much instantaneous destruction of all life on Earth, though. The asteroid that wiped out the dinosaurs was about 10 kilometers in diameter. The moon is about 3200 kilometers in diameter. (Earth is about 12,600 km diameter, for reference.) Literally nothing would survive, and both the moon and Earth's crust would probably re-liquify and melt together until the remnants of the moon became part of Earth.

Somewhat amusingly, the current theory of how the moon was formed is basically the same thing in reverse. Something roughly the size of Mars (~6600 km diameter) slammed into Earth but hit off-center, doing the whole explode-and-melt thing I just described, but the debris coalesced and formed two separate masses (the Earth and the moon) instead of a just one.

edited 28th Apr '16 8:42:15 PM by NativeJovian

The math's well over my head but a quick search found this for how long it would take two mutually gravitating bodies to collide. The general free-fall equation should get you a decent ballpark estimate though since the moon's gravitational influence on the earth is relatively minimal and gives a result of 8852.53 seconds or 2 hours 27 minutes and 32.53 seconds.

As for the second part of your question I'd think the fastest lethal result of the collision would be the overpressure wave/ firestorm through the atmosphere which if I'm remembering my physics right is limited to propagating at the speed of sound. If you take 1/2 earth's circumference^* 40.075*10^6 m and divide it by the speed of sound^* 340.29 m/s you should get a fairly good estimate of the time it takes for most complex life to die^* 83388.82s or 23 hours 9 minutes and 48.82 seconds; if you want to use some other definition of rendering the earth a wasteland thing's get much more complex.

And that's what I get for getting intrigued and trying to do the math out while half asleep.

edited 28th Apr '16 8:46:49 PM by Jaustin89*

Wouldn't the gravity and tidal forces from the moons decent start destroying and killing things before it even hit at that size?

edited 28th Apr '16 9:07:07 PM by Imca