▲ 22 points
back
14 comments
"According to the European Space Agency, researchers estimate that Earth orbit is cluttered with about 34,000 debris objects at least 4 inches (10 centimeters) wide and 128 million pieces that are 1 millimeter across or larger."
http://www.stuffin.space does a wonderful job of showing this by searching for "DEB" which is how debris is labeled. When technology will bring down costs, we will likely see a boom in orbit cleaning missions by private companies with their fleet of automated space drones wandering around, capturing objects, putting them in space litter boxes and throwing them either towards the Sun, or down to Earth or the Moon so they can be recycled.
Why would private companies do this? Who is paying them and how would the cost structure work?
Debris in orbit is not like trash on a field. It is moving at several km/s and is thousands of miles away. Good luck finding, intercepting, and then spending enough energy to de-orbit anything large, let alone tiny objects you can't see. I can't even imagine doing this millions of times.
> Why would private companies do this? Who is paying them and how would the cost structure work?
Gen. David Thompson:
“I’ll pay by the ton if they can remove debris” [0]
> Good luck finding...
“the military announced that its space fence is fully operational and can now track items that are 10 centimeters or larger in size.” [1]
[0] https://spacenews.com/u-s-space-force-would-support-commerci...
[1] https://federalnewsnetwork.com/defense-main/2020/11/dod-want...
Ground based debris tracking (military and private [Leo Labs]) can provide excellent rough estimates where orbital de orbiting systems should look to hone in on with sensors. From there, use lasers to ablate or push with photons direct debris to more optimal de orbit trajectories. Your cleanup volume is limited by the equipment service life and energy budget (more platforms, faster cleanup).
You’re right a private company isn’t going to do this for free unless it’s to protect their own orbiting assets, and a sponsor or several would need to be found for this “commons cleanup”.
> You’re right a private company isn’t going to do this for free unless it’s to protect their own orbiting assets,
In other news, SpaceX will be clearing out the 550km shell in a few years. (Mostly kidding, but they do have the motivation now)
The simple answer to this of course is you do not "de-orbit anything large". In fact, such a thing is catastrophically wasteful since anything of significant mass that has already paid the heavy kinetic energy toll required to get itself to orbit should be recycled for construction material. The economics work out very differently from the ground where normally the energy required to recycle something far exceeds that required to get a fresh supply.
Anything too small for such use or too small to be directly targeted with ablating lasers (as another commentor suggested) can be de-orbited with normal light. It just takes a tiny amount of net momentum to send something on crash course for the atmosphere and since most debris lie on fairly well defined orbital bands, we can use reflectors to bath those swaths of space with enough light to gentle push anything there into oblivion.
For anything that lies outside those bands, by the time we have enough infrastructure up there for those to have any significant chance of collision, we will likely have launch assist technologies like rotavators and orbital rings which means that station and vessels hulls can be made far thicker than the necessarily spartan standards of today.
only a casual space enthusiast, but I don't really see how this is viable. if you want to reuse your cleaning drone, you pretty much have to match orbit with every single piece of debris you pick up. this seems like it would be prohibitively expensive in delta-v for the foreseeable future.
They would have to be deorbited or possibly boosted to a higher orbit as the energy cost to send them into the sun, IIRC, is way too high.
it is in fact less energy to send something at escape velocity out of the solar system from earth than to slow it down to to fall into the sun.
I learned from this article that there is a non-metric ton :(.
(The idea didn't even occur to me. The German school system taught me 1t=1000kg, and that's it.)
It’s worse than that:
British English (and the SI standard) uses the spelling "tonne" to mean 1000kg, with "ton" meaning one of the obsolete units. American English prefers "metric ton", but they haven't obsoleted the old units.
The ESA uses "tonne": https://www.esa.int/Safety_Security/Space_Debris/Space_debri...
A "tun" is a type of barrel (Latin: tunna, German "Tonne"). One could contain roughly a tonne of liquid.
An alternative to deorbiting all this junk would be to aggregate multiple smaller pieces into a single trash pile. You could sweep all the trash from a swath of orbit, and tie it all together. Next you attach a single rocket to provide an emergency manouvering capability. Eventually, decades from now, you send a recycling unit to reprocess all these highly refined materials into something useful.
Just tow normal trash bags behind it! I solved the space trash problem!