Cleaning up Kessler syndrome

[farmerben]

What are some of the proposed methods for clearing orbital debris?

My favorite idea is a cannon that shoots blocks ice H20 or dry ice CO2.  With this the projectiles evaporate.  Whereas using metal bullets limits the angles where you can safely use it without orbiting your projectiles.  You need a cannon going in each direction, clockwise and counterclockwise as viewed from north pole.  Use a cannon going opposite direction to the target.  The cannons themselves need not be very powerful in terms of projectile speed.  We try to intersect space junk near it's apogee and shoot it with a block of ice.  Relative velocities will be in excess of 14km/s.  The target could shatter, but all the small fragments will deorbit faster.  Everything will be reduced to a lower perigee, I think.  A miss is expensive in terms of payload cost, but not dangerous because it will ablate away into gas on its own.

 

What else?  Giant nets, magnets, radioactive tracers...  Use tritium ice so at least you can easily track your projectile and tell how it disintegrates.

Edited July 4 by farmerben

[Errol]

This sounds like it would generate large clouds of debris, and isn't all that different from already conducted missile tests against satellites. The problem you run into is trying to impart enough energy into your payload to get it suborbital without completely destroying it, which I don't think would be possible. If it were able to survive traveling down the barrel of the canon, it would surely get destroyed on contact with the atmosphere trying to travel at near orbital speeds at sea level. This is why rockets carry fuel with them, so they can accelerate gradually through the atmosphere.

My favorite solution is giant ground based lasers that slowly melt the satellites, causing the the orbit to decay faster than normal.

[farmerben]

I wasn't specific enough.  The cannons are in orbit.  They don't need high muzzle velocity, because you get around 14 km/s relative by counter orbiting the target.  Any hit is likely to shatter the target, but all the fragments will be going the same direction which happens to be the direction you need to deorbit.  

[NFUN]

[kerbiloid]

With

[darthgently]

The counter orbit is key.  Even an orbital laser or a big solar mirror in counter orbit to the debris could ablate the prograde side of the debris at every encounter and incrementally give it a retrograde nudge from the ablation or even the raw reflected solar pressure

I should clarify that the laser/mirror sat can slightly lower the orbital energy of thousands of encountered pieces of debris each orbit.  It doesn't just hunt down one target at a time, but rather clears out the zone near its orbit over time by multiplexing and iterating over all targets of opportunity in range that are presenting their prograde surface

Each of these "deorbitors" would also measure changes in orbits of debris and be constantly updating a central mapping database

Debris lowered from a higher orbit would  then get the attention of another deorbitor in a lower orbit

Edited July 4 by darthgently

[boriz]

Many small capture and de-orbit units [CDU] launched together, like Starlink. Each unit would have a small OMS and a capture net. Just prior to capture, the CDU spins axially to 'flail' the net wide open and to help it 'wrap' around the target.

To reduce tumbling during the post capture burn, the net, once secured, is released on the end of a tether and the CDU will provide it's burn from behind (retrograde to) the tethered payload.

Something like this:

 

The octostrut structure at the top is just to simulate the bundled net. After it is flailed, it will be maybe 50 times that diameter.

Each unit would weigh, maybe 50kg-100kg and you could launch them in batches of say ten or twenty.

Edited July 4 by boriz

[darthgently]

3 hours ago, boriz said:

Many small capture and de-orbit units [CDU] launched together, like Starlink. Each unit would have a small OMS and a capture net. Just prior to capture, the CDU spins axially to 'flail' the net wide open and to help it 'wrap' around the target.

To reduce tumbling during the post capture burn, the net, once secured, is released on the end of a tether and the CDU will provide it's burn from behind (retrograde to) the tethered payload.

Something like this:

 

The octostrut structure at the top is just to simulate the bundled net. After it is flailed, it will be maybe 50 times that diameter.

Each unit would weigh, maybe 50kg-100kg and you could launch them in batches of say ten or twenty.

A good approach but the kamikaze aspect puts me off.  I like an approach where the device can be useful many times

[Nuke]

ive more than once sent kerbals out of the ship to push. most often in an effort to deorbit something or at least get it to scrape the atmosphere enough to come down over a series of orbits. we dont have any kerbals but we can make a robot (bonus points if it looks like a kerbal). using a few retractable probes (perhaps on a tripod of linear actuators) tipped in a sticky rubber material and using thrust gravity to hold it in place. you approach the satellite and take some high resolution images for analysis on the ground. assess spin and try to determine the cg (either by analyzing its spin or looking up design schematics) and find push points. first use the probes to halt the spin and reorient the satellite. then approach from the from the prograde side land the probes in unison while simultaneously applying thrust. lower its perigee to a re-entry orbit. then just back off, re-orbit and go for the next piece of space junk, or return to a station for refueling and maintenance. it makes since as you can de orbit several pieces of space junk between refuelings and dont become junk themselves.

[boriz]

De-orbiting space junk is pretty much indistinguishable from de-orbiting military targets. This dual-use aspect makes me suspect that tech similar to this is likely already being secretly developed, or indeed may already be deployed. Tracking ... waiting ... cough ... X-37 ... cough.

Nothing stopping you from making it stealth, so the 'enemy' doesn't know it's there and can't track it.

Just a little more nightmare food for y'all, in case you don't have quite enough.

[kerbiloid]

A nuclear tug with ion engines and laser.

Evaporates small pieces, partially evaporates big things to create a gas jet pushing it retrogradely.

[boriz]

2 hours ago, kerbiloid said:

A nuclear tug with ion engines and laser.

Evaporates small pieces, partially evaporates big things to create a gas jet pushing it retrogradely.

Nuclear anything in Earth orbit is a terrible idea. Too much potential for disaster. Can you imagine if it develops a fault, or is hit by some space junk (irony?), you lose control, it self de-orbits at a random location and scatters long-life radioactive isotopes into the upper atmosphere? *shudder*

It could probably work with solar, but it would absolutely violate international treaties on spaceborne weapons. Again, dual-use issue.

[farmerben]

What I'm hearing is that you need to nearly match the orbit of each piece of junk you want to catch.  Nets are not going to work at high velocity.  

 

Now there is a graveyard orbit just above geostationary orbit.  This junk is all moving with roughly the same velocity including direction.  It's too far out to easily deorbit, (easier to crash into the Moon in fact)  Out there a net that collects debris and keeps it concentrated makes some sense.

[kerbiloid]

5 hours ago, boriz said:

Nuclear anything in Earth orbit is a terrible idea. Too much potential for disaster. Can you imagine if it develops a fault, or is hit by some space junk (irony?), you lose control, it self de-orbits at a random location and scatters long-life radioactive isotopes into the upper atmosphere?

It worked https://en.wikipedia.org/wiki/Nuclear_power_in_space
(once the Canadians even got one for free, right in street)
and is going to continue https://en.wikipedia.org/wiki/TEM_(nuclear_propulsion)

[boriz]

26 minutes ago, kerbiloid said:

It worked https://en.wikipedia.org/wiki/Nuclear_power_in_space
(once the Canadians even got one for free, right in street)
and is going to continue https://en.wikipedia.org/wiki/TEM_(nuclear_propulsion)

Deep space, ok. Earth orbit. Very bad idea.

[boriz]

31 minutes ago, farmerben said:

you need to nearly match the orbit of each piece of junk you want to catch.  Nets are not going to work at high velocity.  

Yes. That's right.

The launcher puts you roughly on the same inclination as the target and the onboard OMS does the rendezvous. This system should be good for anything larger than the size of the holes in the net and smaller than say half the diameter of the net. You want some differential velocity to help the net wrap around the target.

[farmerben]

https://www.nasa.gov/smallsat-institute/sst-soa/deorbit-systems/

"

In addition to drag sails, an electromagnetic tether has proven to be an effective deorbit method. This technology uses a conductive tether to generate an electromagnetic force as the tether system moves relative to Earth’s magnetic field. Tethers Unlimited (now Amergint Technologies) developed terminator tape that uses a burn-wire release mechanism to actuate the ejection of the terminator’s cover, deploying a 70 m long conductive tape at the conclusion of the small spacecraft mission. There are currently two main modules. The first, NSTT for NanoSats has a mass of 0.808 kg. The second, CSTT, is made for CubeSats and has a mass of just 0.083 kg."

[magnemoe]

4 hours ago, farmerben said:

https://www.nasa.gov/smallsat-institute/sst-soa/deorbit-systems/

"

In addition to drag sails, an electromagnetic tether has proven to be an effective deorbit method. This technology uses a conductive tether to generate an electromagnetic force as the tether system moves relative to Earth’s magnetic field. Tethers Unlimited (now Amergint Technologies) developed terminator tape that uses a burn-wire release mechanism to actuate the ejection of the terminator’s cover, deploying a 70 m long conductive tape at the conclusion of the small spacecraft mission. There are currently two main modules. The first, NSTT for NanoSats has a mass of 0.808 kg. The second, CSTT, is made for CubeSats and has a mass of just 0.083 kg."

This works for taking down satellites in low orbit after end of mission,  does not work if satellite is dead unless it an independent module with an battery timer and release mechanism. 
And then the main computer need to reset the timer regularly. say daily, without reset the clock ticks down for an month. If computer can not talk to earth it just reset the timer for a month then stop. 
If power is lost the internal battery keeps this alive for say a week then deploy. 

[Nuke]

i think at some point orbital junkyards will become a thing. where you bring in dead sats, salvage them, and use the parts to repair other space infrastructure. probibly a tubelike centrifuge with the lower pressurized deck being for hab, workshops, and warehouse with the upper deck serving as scrapyard (just lay it down on a palette and let spin gravity keep it in place). some conveyance system (think amazon warehouse bots) to bring it into an airlock so the crew doesn't have to suit up every time there is work to do. in the center you have dock and refueling tankage. would make money on support contracts with satellite providers. i figure every time you exhaust a fuel tank, you can cut the end off, stuff it with unsalvagable scrap, load it into a railgun and shoot it towards point nemo (this has an added bonus of boosting orbit). perhaps use it to put satellites back into their orbits after servicing provided its compatible. 

[cubinator]

You could probably have a spacecraft that approaches space debris and spears or tangles it with a disposable electrostatic drag tail, or perhaps even a large inflatable balloon (no power!). The spacecraft could be armed with many of these devices and maneuver to rendezvous with numerous pieces of space junk.

[kerbiloid]

The problem is great delta-V, both from side speed and orbital maneuvering povs.

***

We could just warm the atmosphere a little, to make it pop up and stop the sats and debris by air drag.
The gigaton-class nukes would be very useful for that.

***

Also a micro-nuke inside a water tank on retrograde orbit.

The water droplets at 15 km/s speed would work nice.

***

Also a micro-nuke inside a water tank on retrograde orbit.

The water droplets at 15 km/s speed would work nice.

[boriz]

Tried an air launched capture and de-orbit. Works great. https://forum.kerbalspaceprogram.com/topic/27292-what-did-you-do-in-ksp1-today/?do=findComment&comment=4405720