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Satellite guided to assisted crash in Atlantic in world first

theguardian.com

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Re: Satellite guided to assisted crash in Atlantic in world first

#41

Post by bewaretheirs »

KRAKRISMOTT wrote: post #5
Renaud wrote: post #4

Maybe it would be time to have a global agreement that all satellites must implement the means of "disposal re-entry" so they can be taken out of the space scrapyard and safely (as much as possible anyway) crashed to earth. The amount of debris in space is going to be a problem that's going to be both costly to solve and very detrimental to future space systems if we continue to not do enough about it.

Not likely. The re entry tech is a critical component of ICBMs. Satellites are relatively easy in comparison, they are just a orbiting computer with a sophisticated radio/signaling processing stack. Most countries can build satellites, but the countries that can put them into orbit are all significant powers. I doubt major powers would be willing to transfer smaller players the technology for controlling re-entry.

The reentry tech in ICBMs has nothing to do with satellite disposal, and, in fact, would make satellite disposal more hazardous (because it would mean the satellite would reenter in one piece rather than breaking up into smaller pieces that are more likely to burn up/melt in the atmosphere).

An ICBM warhead reaches space but at suborbital speeds. It never reaches orbital velocity and will reenter no matter what; it has a heat shield so that the warhead remains intact when descending through the atmosphere.

For satellite disposal, the satellite starts off at orbital velocity and needs to be decelerated above the atmosphere to drop the low point in the orbit far enough that the atmosphere will decelerate it below orbital velocity.

https://what-if.xkcd.com/58/ has a good overview of the difference between suborbital and orbital velocity.

Re: Satellite guided to assisted crash in Atlantic in world first

#42

Post by bewaretheirs »

pmontra wrote: post #6
KRAKRISMOTT wrote: post #5

Earlier quoted context omitted.

Not likely. The re entry tech is a critical component of ICBMs. Satellites are relatively easy in comparison, they are just a orbiting computer with a sophisticated radio/signaling processing stack. Most countries can build satellites, but the countries that can put them into orbit are all significant powers. I doubt major powers would be willing to transfer smaller players the technology for controlling re-entry.

Would it be possible that whoever launches the satellite (in a major power) somehow adds to it a re-entry module, so the knowledge and sensible devices stay out of the reach of lesser powers?

It would make more sense to ensure that any sensitive technology on board is in a demisable subunit that will melt during reentry, so nobody has a chance to snag it after it reenters.

This is also a safety consideration in satellite design - see, for instance: https://spectrum.ieee.org/spacex-claims-to-have-redesigned-i...

If the whole thing comes apart into tiny pieces, you have no chance that anyone/anything on the ground will be injured/damaged by falling debris..

Re: Satellite guided to assisted crash in Atlantic in world first

#43

Post by skinner927 »

coolhand2120 wrote: post #40

If the area above the earth is many orders of magnitude larger than the earth’s oceans, and the oceans are vast in the extreme, what really are the chances of a collision given the relatively small amount of debris in orbit? One can easily find a debris map online. Compared to say “ships in the ocean” the number of “satellites in orbit” must be tiny. And the ships exist on a 2D surface, so are that much more likely t…

Orbits degrade over time. A defunct satellite out of propellant has no guarantees to “stay in its lane”. Space debris are already an issue and we’ve only been putting things in space ~66 years.

Imagine if every ship to ever sail was still afloat and never sank. We’d have thousands of unmanned, uncontrollable vessels ping-ponging around the ocean.

Re: Satellite guided to assisted crash in Atlantic in world first

#44

Post by Rebelgecko »

coolhand2120 wrote: post #40

If the area above the earth is many orders of magnitude larger than the earth’s oceans, and the oceans are vast in the extreme, what really are the chances of a collision given the relatively small amount of debris in orbit? One can easily find a debris map online. Compared to say “ships in the ocean” the number of “satellites in orbit” must be tiny. And the ships exist on a 2D surface, so are that much more likely t…

The number of satellites is less than the number of oceangoing ships, but satellites are on track to be ahead in the next decade or so.

Then if you start counting every single piece of debris a satellite can run into, you're looking at millions of objects. Unlike ships, the debris (and even many satellites) doesn't have anyone "on watch" and there's no way to steer out of the way at the last minute. Because of how orbits work you can't really organize traffic into "shipping lanes".

If you want to do the math yourself, NORAD publishes satellite orbital parameters, which can be used to look for potential conjunctions. You can also sign up for an account at https://www.space-track.org to see the Space Force's data, or CelesTrak for something similar that isn't login-walled (https://celestrak.org/SOCRATES/). The tl;dr is that it's not rare for 2 satellites (or a satellite+debris) to have a 1 in 10,000 chance of crashing into each other. As more and more satellites go up and more and more "1 in 10,000" events happen on a daily basis, more conjunctions will occur. Each conjunction can create thousands of pieces of debris, which exacerbates the problem- nowadays I think ~30% of all debris in LEO comes from China's 2007 ASAT test.

Re: Satellite guided to assisted crash in Atlantic in world first

#45

Post by Rebelgecko »

KRAKRISMOTT wrote: post #5
Renaud wrote: post #4

Maybe it would be time to have a global agreement that all satellites must implement the means of "disposal re-entry" so they can be taken out of the space scrapyard and safely (as much as possible anyway) crashed to earth. The amount of debris in space is going to be a problem that's going to be both costly to solve and very detrimental to future space systems if we continue to not do enough about it.

Not likely. The re entry tech is a critical component of ICBMs. Satellites are relatively easy in comparison, they are just a orbiting computer with a sophisticated radio/signaling processing stack. Most countries can build satellites, but the countries that can put them into orbit are all significant powers. I doubt major powers would be willing to transfer smaller players the technology for controlling re-entry.

I think tech for gradual reentries (stuff like electromagnetic tethers) is not useful for ICBMS

Re: Satellite guided to assisted crash in Atlantic in world first

#46

Post by rzimmerman »

Renaud wrote: post #4

Maybe it would be time to have a global agreement that all satellites must implement the means of "disposal re-entry" so they can be taken out of the space scrapyard and safely (as much as possible anyway) crashed to earth. The amount of debris in space is going to be a problem that's going to be both costly to solve and very detrimental to future space systems if we continue to not do enough about it.

This is already (effectively) the case. All satellites launched from the US need to have a plan to safely deorbit within 25 years after they’re no longer in use. I believe this was recently lowered to 5 years. For many satellites this just means natural decay and burn up on reentry. Satellite owners need to submit an orbital debris analysis as well to prove they won’t hit anything. Other countries and the EU have similar (often more strict) regulations.

Re: Satellite guided to assisted crash in Atlantic in world first

#47

Post by rzimmerman »

dotnet00 wrote: post #29

I'm not really getting what makes this a world first? Controlled deorbits have been a thing for a while, and if we're talking about deorbits designed to minimize risk of debris impact, IIRC Starlink satellites were designed to maximize the amount of the satellite that is vaporized by reentry. Edit: Ah, the "world's first" is that they were able to choose where any parts that aren't vaporized would crash. The esa arti…

I’m fairly confident this is not a first. It’s just good behavior if you have a defunct but controlable satellite in low earth orbit. A best-effort burn to deplete fuel and aim for an ocean is an obvious choice. While it’s interesting, it is not novel and I think the reporter over-sensationalized here.
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