Making Earth Orbit to Escape Velocity Spaceflight Affordable

Making Earth to orbit spaceflight affordable to everyone is only the beginning.

The second step is to make getting to escape velocity affordable to everyone.

Accelerating to escape velocity is what will allow us to start moving out into the solar system.

The whole purpose of making beyond Earth orbit spaceflight affordable to everyone is so that we can start building a spacefaring civilization.  A trip to the Moon, a trip to an outpost space station at L2, a trip to a near-Earth asteroid, a trip to Mars, all of them requires accelerating to escape velocity and beyond.

This is not an insignificant step.

A vertical take-off rocket needs to accelerate to 9,100 meters per second in order to make it to low Earth orbit.  That includes 7,800 meters per second for low Earth orbit, plus 1,300 meters per second for drag and gravity losses.  To go from low Earth orbit to escape velocity requires another 3,230 meters per second of speed.  That is over 1/3 of the speed needed to reach low Earth orbit.  It takes a lot of propellant to accelerate that much.  For example, the Saturn V rocket that America used to go to the Moon in the late 1960s and early 1970s, could place 161,600 kilograms in low Earth orbit.  The amount of useful payload that it could send to the Moon was 62,300 kilograms.  Of the difference: 84,160 kilograms was propellant; and, 15,140 kilograms was the expendable upper stage and support structure.  Even if the upper stage for doing this were made reusable, there would still be the cost of launching all the propellant for another flight into Earth orbit, plus the need for the upper stage to carry enough extra propellant so that it could return to low Earth orbit.  None of this is inexpensive.

So how do we make low Earth orbit to escape velocity flight affordable?

The answer is a Skyhook.

In the same way that the lower end of the Skyhook reduces the velocity that a launch vehicle needs to achieve to reach low Earth orbit, the upper end of a mature Skyhook can accelerate a spacecraft to escape velocity without the need for an upper stage or by burning any of the spacecraft’s onboard propellant.  The power for this comes from the ion propulsion system on the Skyhook.  The Skyhook uses its ion propulsion system to gradually increase its orbital altitude and orbital energy, altitude and energy that it gives to the departing spacecraft when the departing spacecraft releases from the upper end of the Skyhook.  In effect, the Skyhook acts as a reusable energy storage device for both arriving and departing spacecraft that never leaves Earth orbit.  The amount of energy being stored by the Skyhook at any given moment is measured by the height of its orbit.