Take a Train to Space
There are some really amazing ideas out there. Here is one of them.
Startram – maglev train to low earth orbit
Getting into space is one of the harder tasks to be taken on by humanity. The present cost of inserting a kilogram (2.2 lb) of cargo by rocket into Low Earth Orbit (LEO) is about US$10,000. A manned launch to LEO costs about $100,000 per kilogram of passenger. But who says we have to reach orbit by means of rocket propulsion alone? Instead, imagine sitting back in a comfortable magnetic levitation (maglev) train and taking a train ride into orbit.
The system would see a spacecraft magnetically levitated to avoid friction, while the same magnetic system is used to accelerate the spacecraft to orbital velocities – just under 9 km/sec (5.6 miles/s). Maglev passenger trains have carried passengers at nearly 600 kilometers per hour (373 mph) – spacecraft have to be some 50 times faster, but the physics and much of the engineering is the same.
The scope of the project is challenging. A launch system design for routine passenger flight into LEO should have rather low acceleration – perhaps about 3 g’s maximum, which then requires 5 minutes of acceleration to reach LEO transfer velocities. In that period, the spacecraft will have traveled 1,000 miles (1,609 km). The maglev track must be 1,000 miles in length – similar in size to maglev train tracks being considered for cross-country transportation.
Like a train, the Startram track can follow the surface of the Earth for most of this length. Side forces associated with the curvature of the surface can be accommodated by the design, but not the drag and sonic shock waves of a craft traveling at hypersonic velocity at sea level – the spacecraft and launching track would be torn to shreds.
To avoid this, the Startram track must be contained inside a vacuum tube with vents to allow air compressed in front of the spacecraft to escape the tube. A vacuum equivalent to atmospheric conditions at an altitude of 75 km (about 0.01 Torr) should suffice for the efficient operation of the Startram launch system. Rapid pumping to achieve this pressure will be provided by a magnetohydrodynamic vacuum pump.
If the entire Startram tube is at sea level, on exiting the tube the spacecraft will suddenly be subjected to several hundred g’s due to atmospheric drag – rather like hitting a brick wall. To reduce this effect to a tolerable acceleration, the end of the Startram vacuum tube must be elevated to an altitude of about 20 km (12 miles). At this height, the initial deceleration from atmospheric drag will be less than 3 g’s, and will rapidly decrease as the spacecraft reaches higher altitudes.