Momentum transfer system for space access and return to earth

Momentum transfer system for space access and return to earth.

20110714 JEDCline

I thought of this idea back in the early 1980's, and have mentioned it, and others may have though of similar things too. But here is a description of it; I have not heard of it elsewhere, but not looked for it either.

The purpose is to use some of the energy of spacecraft returning from space down to earth, to give energy to spacecraft heading up to space from earth. To make the process significantly more efficient, useful for routine frequent trips, unlike current one-shot trips.

The concept basically would work as follows. (I hope to make graphics for each of these steps, but first I need to learn how to do better graphics on computer. Unless someone else wants to have a go at doing the graphics, that would be fine too, if coordinating with me on the task.)

A platform is built in low earth orbit, perhaps at 100 Km if it is to be used frequently. The platform is kilometers long, length determined by several factors to be described below. It consists of a guidance track and two sets of large compression springs. An electromagnetic storage system was intended in the earlier version of the concept; but now I think of simplicity mindless functionality as increased reliability. Thus, plain ordinary compressions springs.

In operation, a spacecraft incoming at high velocity towards the Earth, guides itself to land on the back end of the platform, much like an aircraft lands on an aircraft carrier at this point. It snags and drops onto a guiding trackway, and starts compressing the forward set of compression springs.

When the spacecraft and platform have matched velocity (transferring momentum to the platform) the spring then starts decompressing shoving the spacecraft backwards and back off the input end of the platform.

The spacecraft ideally has lost most its forward momentum at this point, dropping like a rock starting from the 110 Km altitude, instead of re-entering like a meteor. Spacecraft vehicle then builds up speed in the drop into the atmosphere, much as a simple winged spacecraft would do, much like vehicles already being tested for commercial parabolic rides for brief trips to space.

This would enable such vehicles to reach orbit and beyond.

Continuing, the way this would work in the upward direction is as follows:

The platform is now at its higher altitude, say 110 km, having absorbed much of the previous incoming spacecraft's momentum energy, increasing the platform's velocity and raising it to a higher altitude, say 110 km.

A winged passenger spacecraft is launched from the ground in a parabolic return to earth trajectory, much as is already being planned for brief passenger rides to space. But this time, near the top of its parabolic trajectory, the spacecraft uses positioning thruster engines to align with the orbiting platform, and gets snagged, same as the incoming spacecraft did earlier. Except this time, it is from the leading end of the orbiting platform. And the other set of compression springs gets compressed as the platform's momentum is transferred to the spacecraft until their velocities are matched. Both are in orbit at about 105km at this point.

The springs, being compressed at this point, then shove the spacecraft forward along the platform's track, decompressing the spring, and flinging the spacecraft out faster than the orbiting platform's velocity.

The platform has thus lost velocity and orbiting altitude, back down to, say, 100 km altitude orbit. The spacecraft, however, has been boosted by the decompressing spring (or electromagnetic equivalent) and is headed up to a higher altitude orbit.

When it or one of its siblings returns from higher orbit, the process is resumed as described at the start of this process, inputting momentum back into the orbiting platform.

The overall result is that a spacecraft vehicle, such as is now planned just for simple parabolic brief rides to 110 km and back down again, can be converted to full orbital capability, and even going to much higher orbits, perhaps to rendezvous with the ISS. Such winged spacecraft can then gently return back to earth the same way, giving up its potential energy to the platform, so that it does not need ablation heat shielding like the Space Shuttle did, nor space capsules do.

It is a far more energy efficient system to get to orbit, than using conventional rocket spacecraft systems as presently planned. But it only works in a routine frequent vehicle access to space and return system, of several trips per week or more.

Jim Cline
Ephrata, WA, 98823

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