Satellite Harpoons Space Debris in Test | Hacker News Reader

Satellite Harpoons Space Debris in Test

theverge.com

36 pointsChuckMcM24 comments

I was really impressed with this, while it is only a test it shows you can build a tungsten penetrator type harpoon and latch a line on to space debris. Once attached adding a small delta V even with something like an ion thruster could accelerate the deorbiting of space junk.

I dont think the delta-v for deorbiting is even necessary. You just need to agglomerate all the debris into one big mass. This will make it easier to track.

In the future, when we need some in-orbit resources, etc, we can use these. (much of the debris is spent booster stages)

You would still need a delta-V to agglomerate multiple debris. Depending on the context, it may be cheaper to just de-orbit them.

We're a long way from recycling stuff in orbit. We've not even started manufacturing anything worthy in orbit.

This is awesome...robotic space whaling! The next “Moby Dick” will be about the quest for the Black Knight.

Life imitates art?

https://www.youtube.com/watch?v=y6miuzFzonU

What’s a bigger concern? Big space debris or small space debris?

The latter. There are more than 170 million objects with dimensions up to 1cm, while the larger ones are less than a million.

Not only that, but they are MUCH harder to track. Tracking systems just aren't good at tracking small things.

1cm objects are currently essentially impossible to track.

So might the risk of harpooning one big thing have a net negative effect by creating more tiny objects?

Yes. It,s nearly impossible to avoid, really. Space debris doesn't really look like a problem that can be solved. It can only be managed.

Other than removed selected really large pieces, such as entire derelict spacecraft, in crowded orbits like GEO where the likelihood of hitting something else is high.

That's what is being assessed with this mission. If creating a few debris with he harpoon allows you to de-orbit the whole debris, which would have generated a certain amount of small debris over time, then it can be a win if the former is smaller than the potential latter.

Also, depending on the orbit considered, the debris generated by the harpoon may be less harmful: they have typically a high surface area/weight ratio so they will deorbit fast if the altitude is low enough, like for this mission.

Wouldn’t it be easier to push objects down towards earth, so the small stuff burns up?

You need to push them in a correct and somewhat precise way so you need to grab the debris somehow before applying the push.

Probably total number of objects.

That was my thought too, I wonder how cubesats will also affect the asteroid belt we're building around earth.

They won't have much of an impact, as at the altitude that they operate and for various regulatory reasons, virtually every cubesat will deorbit and burn up in the atmosphere within 25 years of the launch date, with typical times being more on the order of 5-7 years. Should we reach a point where we decide there are too many cubesats and it is becoming problematic, we slow down or stop launches entirely for a few years and the problem resolves itself.

Depends on how you define concern.

For killing a spacecraft? Small debris. For creating more debris? Big debris.

Big space debris is more dangerous because it can start a Kessler cascade.

In addition, small space debris could conceivably be cleaned up with lasers from the ground. That's not so feasible for bigger stuff.

Depends on what you're concerned about and where it is.

Smaller things are more likely to burn up on reentry, whereas bigger things can partially survive.

Atmospheric drag can also vary based on size and density of debris. IIRC smaller things will reenter more quickly. Which is nice, except smaller debris is harder to track (imagine looking for a fleck of paint that's 500 miles away).

However things are a little different in GEO. The good news is that orbital velocities are lower, so if you hit something it'll be less catastrophic than if you hit it at the same angle in LEO. But tracking things is much harder. In LEO you can follow the wrench that some astronaut dropped 10 years ago. But in GEO there's almost no chance. And there's much less atmospheric drag, so junk can stay up there for hundreds of years.

Predator Satellite. Other satellites will need protection

Considering the amount of space debris out there, is a single harpoon the most practical way to get rid of it all?

I don't think there is any one solution to "all" space debris (perhaps there is but it seems intractable with a single solution to me). However there is always benefit in removing space debris. If this technique was only successful on pieces 5" (10 cm) in size or greater it could still get a lot of stuff out of the way. Especially things that are prone to creating Kessler cascades.

This harpoon is designed to catch big debris. The target used for this demonstration is a honeycomb panel typical of bigger satellites.

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