Debris Intercept Towers

Using launch loop "dynamic structure" technology

Some have suggested using launch-loop-style towers as elevated gantries for orbital rocket launch, bypassing the 200 to 600 m/s atmospheric drag losses of vertical launch from the ground. I hope they do the math - rockets are heavy. The gantries and water-sprayed flame ducts and makeup propellant tanks associated with a launch pad are far heavier.

That said, the notion inspires my favorite phrase, which I hope to hear from many of you, backed by physics and calculation:

That won't work, but this will!

An important, expensive, and neglected space mission is de-orbiting space debris from Low Earth Orbit. I include the spent upper stages used to loft satellites into high orbits, like the Russian Molniya comsats; those derelict upper stages come bombing through LEO at high speed, threaten enormously expensive assets like ISS.

Deorbiting an object means dropping the perigee of its orbit down into the atmosphere, and the best way to do that is to reduce apogee velocity. The second best way to do that is to reduce perigee velocity so much that apogee becomes the new, lower perigee. That requires delivering a lot more delta V, but will eventually bring the object down.

Instead of using a suborbital loop supporting a big chemical rocket, it can instead support a velocity transformer track (as below) to magnetically launch many small (20 kg?) 25 gee vehicles into suborbital retrograde ballistic trajectories. 20 gees and 40 km is 3840 m/s + 430 m/s drag loss (WAG); if the exit is at a 60 degree angle, that is 3320 m/s vertical velocity, an apogee of 900 km, and a retrograde velocity of 1.28 km/s.

After launch, adjust the velocity with laser ablation thrust, from a laser platform suspended under the loop.

What's that good for? Launching canisters of expanding foam precisely in front of a derelict space object, slowing it down and deorbiting it after enough impacts. All earth-orbiting objects cross the equator twice per orbit. One of those crossings must be low enough for this kludge to reach it - a faster launcher will be needed for higher objects.

debris.ods libreoffice spreadsheet ( gate:keithl/launchloop/. )