ISS debris avoidance

[iconoclastmax]

Do "we" have the technology/capability, both actually, to equip satellites/space stations, etc. with some type of shield that could be projected far enough around the object needing protection from space debris, that could burn the debris up or deflect it out of harm's way?...

Maybe use some type of laser/ray type of device?...Yes, I'm in reality talking about some sort of "force" field?....

Maybe you can come up with an idea of how to do it, but it is not possible to make a magic ray to zap them. Take a poke at it . . . . Small things you can't even see to zap (sand grains that make for a bad year in space), big things (bolt sized) you can't really see and vaporize in time, let alone hit. Think hunting bats with a BB gun in the dark, eyes covered, ears plugged. When you don't even know if there are bats in the area.

 

[billslugg]

Intercepting space debris in order to capture it is prohibitively expensive. What would be relatively cheap would be to use a laser to ablade the leading face of the debris thus slowing it down and allowing it to reenter the atmosphere. The incremental out of pocket cost of deorbiting a piece of debris would be only a few dollars.

 

[Catastrophe]

But can it control where larger pieces hit?

Cat

 

[billslugg]

Pieces too large to completely disintegrate would probably need to be intercepted and deorbited in a controlled fashion. Laser ablation would probably be best used on pieces smaller than a few kilograms.

 

[iconoclastmax]

Pieces too large to completely disintegrate would probably need to be intercepted and deorbited in a controlled fashion. Laser ablation would probably be best used on pieces smaller than a few kilograms.

Sounds good on face of it, like your other post, but pieces of a kg or more are still very difficult to see, and pinpoint, so you have to put your large areal laser power density (enough to vaporize a hundred gm of metal in a few square inch area in a second or so ->kilowatts) over a large area (hundreds of square meters) -> BIG POWERFUL LASER, prohibitively so. Kilowatts/cmsquared (to vaporize), over an area of 100 square meters = order gigawatts for seconds. Several large terrestrial powerplant outputs, effective laser power in orbit, focussed, pointed. And these bigger pieces are relatively rare, so you are shooting from dozens of miles or so (unless you spend an infinite amount of fuel roughly matching orbits with dozens or hundreds of objects (especially inclination, see Kerbal!!). You are still firing a gigawatt laser at 100% duty factor for a second or two. From a moving satellite pointed at another moving satellite dozens of miles away. And do it up to a hundred times over year or more in orbit with no replenishment. Still no can do.

And don't just reply ad hoc that it can be done, unless you do an analysis like this showing your work to back it up.

 

[billslugg]

This would not require a gigawatt laser operating from the ground. It would require only enough energy to change the orbit of the several kilogram mass enough such that it started being dragged by the atmosphere.

"The delta-v required to return from Near-Earth objects is usually quite small, sometimes as low as 60 m/s (200 ft/s)"
"Near-Earth Asteroid Delta-V for Spacecraft Rendezvous". JPL NASA. Archived from the original on 2001-06-03.

A one kilogram mass at orbital velocity of 17,500 mph (7830 meters per second) has a kinetic energy of 30.65 megajoules. Reducing its velocity by 60 m/s reduces its kinetic energy to 30.19 megajoules. The delta is 468,000 joules. A one second blast at 500kW would suffice.

Here is a report of development of a 300kW laser which would operate off batteries.US developing its most powerful laser weapon to blast missiles out the sky after China’s ‘round the world’ nuke test | The US Sun (the-sun.com)

A phased arrar radar in orbit combined with a megawatt class laser should have no problem doing this. Here is an article summarizing the state of the research two years ago.
Laser Weapons Are Headed to Space to Shoot Down Missiles | The National Interest

 

[billslugg]

Just to be clear about how this would work, the laser beam would be aimed at the leading face of the object. It would need to be of very short duration to minimize the depth of penetration. This would mean a smaller amount of metal evaporated and more of the heat dedicated to superheating the metal. The evaporated material would travel in the opposite direction of the object, the object itself would slow down. The energy imparted by the laser beam would be equally split between the ablated material and the object. Half the imparted momentum would be carried away by the material, the other half dedicated to slowing the object. Depending on the rate at which heat is transferred into the material prior to melting and vaporizing it a pulse duration would need to be determined. It might suffice to use a megawatt class laser for one second or perhaps a gigawatt class laser for a millisecond.
Perhaps such lasers are not currently feasible but at the rate we are advancing it is only a matter of time.

 

[Pogo]

Of course, the target object would be moving at something better than 7 km per second, would be hard to hold the laser on target. Once we can get that GW laser on the job, in one millisecond, the target will move only 7 meters - easier to do.

But, a GW laser, how much will the atmosphere dissipate and attenuate the beam?

 

[billslugg]

It would be best to place the laser in orbit, above the atmosphere. The laser would be aimed by a swivelling mirror that could move very fast. Every photographic satellite in orbit right now can track the Earth below moving at 7 km per second. This is well within our current capabilities.