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NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

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Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#21

Post by theandrewbailey »

JKCalhoun wrote: post #13

I never understood why a free-fall from space with a parachute would not work. (I bring this up because I would propose bringing down sections of ISS with extremely large parachutes.) I get there is no air in space, and how thin it is as you approach the Earth's surface. But it is a gradient after all. If a falling body begins to heat up, that suggests it has entered a region with some atmosphere — and so some parach…

> How is the model in my head wrong? Does the parachute effectiveness lag with regard to the rise of the "heat gradient"?

Consider that landing on Mars is difficult: it has enough of an atmosphere to be a problem (lots of heat on re-entry), but too thin to be useful (limited drag).

With that in mind, my guess is that the ISS would heat up faster than the parachute would slow it down.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#22

Post by Someone »

_Microft wrote: post #12

Idea: gently boost it into a much higher orbit, leave it there and designate it as (one of) the first Space Heritage Site(s).

First? Neil Armstrong’s footprints on the moon already are somewhat protected (https://astronomy.com/news/2021/01/neil-armstrongs-bootprint...)

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#23

Post by rtkwe »

JKCalhoun wrote: post #13

I never understood why a free-fall from space with a parachute would not work. (I bring this up because I would propose bringing down sections of ISS with extremely large parachutes.) I get there is no air in space, and how thin it is as you approach the Earth's surface. But it is a gradient after all. If a falling body begins to heat up, that suggests it has entered a region with some atmosphere — and so some parach…

Basically yes things start falling out of the sky faster than you can slow them down to avoid burning up causing them to fall deeper into the atmosphere where the parachute just gets ripped apart or your spacecraft just melts from the friction of slamming through the atmosphere at Mach 20+. Orbiting objects are just going way faster than you can slow down with just a parachute you have to have something in front to protect the craft, so far they're all heat shields of some sort either ablative or extremely insulative so the flimsy spacecraft doesn't become a giant piece of slag.

One of the big problems with landing on Mars is related to this. The atmosphere is thick enough to cause heat problems but thin enough that slowing down enough to deploy a parachute is hard so we're limited in the amount of mass we can send until we figure out inflatable heat shields to increase the cross sectional area so we can slow down enough for parachutes to work. Otherwise you have to use a Starship style powered landing all the way down. With that you have to carry all that fuel to Mars which again cuts down on the mass you can actually land.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#24

Post by yummypaint »

JKCalhoun wrote: post #13

I never understood why a free-fall from space with a parachute would not work. (I bring this up because I would propose bringing down sections of ISS with extremely large parachutes.) I get there is no air in space, and how thin it is as you approach the Earth's surface. But it is a gradient after all. If a falling body begins to heat up, that suggests it has entered a region with some atmosphere — and so some parach…

I think part of the problem is that there is a regime where the atmosphere is too sparse to really act like a fluid or carry away heat. The kinetic energy of the falling object ultimately has to get converted to heat, but the balance between the power delivered to the spacecraft and the power dissipated back to the environment changes significantly with altitude. I think that period of only being able to really dissipate heat by radiation is what motivates the use of insulating tiles. That way the hottest surfaces can be allowed to reach high temperatures without harming the sensitive parts, and the power emitted scales as the temperature to the 4th power, so letting a small part get very hot provides better cooling than spreading that energy evenly out over the whole spacecraft.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#25

Post by 0xFFFE »

_Microft wrote: post #12

Idea: gently boost it into a much higher orbit, leave it there and designate it as (one of) the first Space Heritage Site(s).

You need to keep it fueled for it to maintain whatever orbit it gets pushed into. Orbital decay and everything.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#26

Post by hakko »

The ISS takes over 10% of NASA's budget at over $3b/year in maintenance, so they won't be able to take care of it and sustain their proposed moon mission at the same time. Plus the low-hanging fruit for research has already been performed. My unpopular opinion is that manned spaceflight is an expensive national vanity project for modest research gains, and the projects that have been most successfull from a science perspective have been the deep space probes/space telescopes.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#27

Post by jqpabc123 »

JKCalhoun wrote: post #9
jqpabc123 wrote: post #5

Earlier quoted context omitted.

So we need the ISS so we can use taxpayer money to fund billionaires to develop rockets to launch to the ISS? See here: https://en.m.wikipedia.org/wiki/Circular_reasoning Where would we be without SpaceX? Pretty much where we are now --- struggling to find enough chips to build cars and Raspberry PIs.

It would be nice if we could do both.

Yes. But unfortunately, the one being addressed won't have any real impact for generations while more immediate needs are being ignored.

NASA has spent trillions studying the effects of weightlessness on people.

In comparison, they have spent virtually nothing on protecting the plant from an asteroid strike or mitigating the effects of global warming --- both of which are way more pressing concerns.

Studying people in space is about as practical as addressing global warming by funding research on Dyson spheres.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#28

Post by fernandopj »

_Microft wrote: post #12

Idea: gently boost it into a much higher orbit, leave it there and designate it as (one of) the first Space Heritage Site(s).

I don't think it can just be a "gentle" nudge, it is a massive body and must need a rocket-level thrust to do so, but really, I agree with the idea. Why not?

Dock a custom Dragon with thrust capabilities, put in a higher, more stable orbit. Doesn't even has to be circular, just so we can visit it in the near future.

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#29

Post by spyspy »

JKCalhoun wrote: post #13

I never understood why a free-fall from space with a parachute would not work. (I bring this up because I would propose bringing down sections of ISS with extremely large parachutes.) I get there is no air in space, and how thin it is as you approach the Earth's surface. But it is a gradient after all. If a falling body begins to heat up, that suggests it has entered a region with some atmosphere — and so some parach…

You’d need a parachute designed for very high velocity[1] which does exist but this is still likely unreasonable. Heat goes up much faster than drag relative to speed.

1. https://en.wikipedia.org/wiki/Ballute

Re: NASA plans to retire the ISS by 2031 by crashing it into the Pacific Ocean

#30

Post by 4gotunameagain »

fernandopj wrote: post #28
_Microft wrote: post #12

Idea: gently boost it into a much higher orbit, leave it there and designate it as (one of) the first Space Heritage Site(s).

I don't think it can just be a "gentle" nudge, it is a massive body and must need a rocket-level thrust to do so, but really, I agree with the idea. Why not? Dock a custom Dragon with thrust capabilities, put in a higher, more stable orbit. Doesn't even has to be circular, just so we can visit it in the near future.

Well in theory it could even be done with the station keeping capable modules, a very gentle push indeed, it would just take time and maybe refueling..
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