71–80 of 96 posts
Makes me wonder if you could slingshot around the sun towards relativistic speeds with thermal power. At the very least it could save fuel on the egress, if not the second half. Can you aerobrake around a star?
You can only slingshot around the sun if you were already in a hyperbolic orbit w.r.t the sun. An object in a closed helio centric orbit cannot gain any momentum by "slingshotting" around the sun.
This is great sci-fi fodder, imagine if you could land a tiny craft on that thing and then use the hydrogen as fuel without having to haul all that fuel into deep space (very unlikely to be practical but the idea is exciting).
This is great sci-fi fodder, imagine if you could land a tiny craft on that thing and then use the hydrogen as fuel without having to haul all that fuel into deep space (very unlikely to be practical but the idea is exciting).
About the only good thing it could be used for is reaction mass. But you can use almost anything as reaction mass as long as you have a source of energy, you can exhaust any particles to propel yourself forward, doesn't have to be hydrogen.
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That's really cool. Definitely helpful in order to drop deceleration fuel requirements if we ever manage to put together a relativistic interstellar spacecraft.
In a bit over 1M years another star is expected to pass around 1000 AU from the sun. Chemical rockets should be able to get there in a decade or two. It's a huge stretch, but we have a million years to prepare.
Earlier quoted context omitted.
In a bit over 1M years another star is expected to pass around 1000 AU from the sun. Chemical rockets should be able to get there in a decade or two. It's a huge stretch, but we have a million years to prepare.
Something makes me doubt that humans will still be around at that time.
Is there an element or compound in the universe that will remain a gas at 0K? Does everything become solid at that temp?
0K implies no Brownian motion at all (no thermal energy), so there would be no force to keep the molecules apart.
Makes me wonder if you could slingshot around the sun towards relativistic speeds with thermal power. At the very least it could save fuel on the egress, if not the second half. Can you aerobrake around a star?
Thermal power requires a reservoir of cold temperature; your car's engine would do nothing if the incoming air was just as hot as the post-ignited air.
If I repeat this long enough, my engine will melt, but that's a minor matter of materials science. Maybe I can win my drag race before it melts. Is that the limiting factor or is there some other reason I'm missing that we need a heat gradient?
This is great sci-fi fodder, imagine if you could land a tiny craft on that thing and then use the hydrogen as fuel without having to haul all that fuel into deep space (very unlikely to be practical but the idea is exciting).
Yeah, imagine you have whole lot of hydrogen and no oxygen to get it to burn. You are going to freeze to death while moving nowhere. About the only good thing it could be used for is reaction mass. But you can use almost anything as reaction mass as long as you have a source of energy, you can exhaust any particles to propel yourself forward, doesn't have to be hydrogen.
Well, not today, but we can't reach it today either.
Earlier quoted context omitted.
Imagine you just land a tiny craft on that thing and let the thing take you to interestelar space without you having to burn no more fuel. Unfortunately, if you can't catch it, you don't need it for that, as you'll be traveling faster that it to be able to intercept it and would just burn fuel trying to break enough to match its speed.
Rule 1 of orbital mechanics: if you're about to dock with something, you're already on the same trajectory as that thing. Might make a good radiation shield, though.