More on orbiting momentum transfer concept

Since posting the immediately previous post here on momentum transfer, I have been having a somewhat spicy post chat with folks at the LUF group. To defend my concept I have had to make it more specific. Here is how it stands right now:

Regarding relative masses, a very heavy platform is going to give the spacecraft maximum push.

A platform of equal mass to the spacecraft simply trades states, the spacecraft taking on orbital velocity and the platform drops like a rock toward the planet.

Something in between seems best to me, for practicality. And for safety if and when the platform takes a dive, for disintegration before reaching ground.

A platform of ten times the spacecraft's mass could even be built and launched in the form of a reentry glider configuration, using a heavy lift conventional launch vehicle to put it into orbit, too.

But in the present context, a simple truss or foamed structure containing the hook and track and long compression springs for this thought experiment.

The major part of the overall energy is input each trip, by the ground-to-intercept with the 110 km high orbiting springy platform. The orbital velocity part is what the concept tries to minimize afterwards. Conserving energy overall, while storing and retrieving energy along the way.

The spacecraft will need to carry fuel and thrusters for some orbital corrections, but not nearly as much as if punching all the way through under its own power, and throwing it all away in hot reentry later.

So. The spacecraft coasts up to 110 km and wonderfully is right there to meet the springy platform as it coasts along in orbit.

The mass of the kilometers long springy platform is ten times the mass of the spacecraft with its payload. The two have a springy collision and the spacecraft bounces forward along the flight path of the platform, at 180% of the velocity of the orbiting platform, which is now going at about 90 percent of what it was going. Platform begins to drop to slightly lower orbit.

Spacecraft takes on an elliptical orbit as a result, going up to about 180 km aphelion where it uses its thrusters to enter circular orbit and match velocities and position with its destination site, perhaps an orbiting inflatable hotel at 180 km.

Am using rough numbers here. If necessary I will go dig to see if I can find my old trusty good slide rule in the boxes in my garage. Or figure out how to do it in Mathematica. Ugh.

After the party is over at the orbiting hotel, the spacecraft casts off, and uses its thrusters, not to do a de-orbit burn, but to put it back into an elliptical orbit that grazes the 100 km orbit where the springy platform is now, and has to be precisely timed so that as the ellipse grazes the platform's path at perihelion it comes in behind at 180% of the velocity when at its upper altitude; it rams the platform's spring from behind; and a bit later for an instant, compresses it to the point they are exactly matched in velocity, which now has boosted the platform part way back up towards its original velocity.

(If it misses at perihelion, the spacecraft continues on around in its elliptical orbit and tweeks its path with thrusters to get it right the next time they meet at perihelion. Thrusters also compensating for the small drag at that altitude, too. Orbital time is on the order of about an hour and a half, before making another try at rendezvous.)

Then the spring decompresses and flings the spacecraft out backwards, at about a relative velocity equal to that of the springy orbiting platform but in the opposite direction. Relative to the planet, that means zero orbital velocity, the state where it found the spacecraft at the top of its parabolic reach originally, and the spacecraft resumes its relatively low energy drop back into dense atmosphere and glides home with some help with its thrusters if necessary.

There was no violation of the laws of conservation of energy along the way; energy was just shared for awhile and then given back again. Timing and positioning relative to the New Mexico Spaceport (or wherever) and the orbiting hotel, is a nightmare for me but likely duck soup for computers.

Chemical thrusters are used with onboard fuel to make up for inefficiencies and orbital tweaks along the way.

Well, the puzzle pieces seem to fit together here for me. Doing the numbers will refine the "abouts."

Labels: , , ,


Post a Comment

Subscribe to Post Comments [Atom]

<< Home