14 Mar 2012

It can be quite difficult to get into space and low Earth orbit (LEO) for us humans.  As of 2012, the cost of a kilogram or 2.2 lb cargo with the aid of a rocket is about USD $10,000.  For humans, manned missions are around $100,000 per kg of person.  So we continue to look for alternative means of reaching Earth orbit, such as the space elevator, which is still off into the future, but what about a magnetic levitation (maglev) train?

Dr. George Maise has invented something called the Startram orbital launch system, in conjunction with Dr. James Powell, one of the inventors of the maglev.  Dr. Powell won the 2002 Franklin Medal in engineering.  The Startram would magnetically levitate the train to prevent friction while at the same time accelerating the train to orbital velocities at around 9 km/sec (5.6 mph).  Regular maglev passenger trains have hit 600 kilometers per hour (373 mph), so this would need to be around 50 times faster.  

Such a system is challenging because ideally a routine passenger flight to LEO should only top out at around 3 g's (three times the force of gravity), and consequently requires 5 minutes of acceleration or about 1,000 miles (1609 km) of travel.  Hence the maglev track needs to be 1,000 miles in length, a similar length that is considered for country-wide transportation.

The Startram can follow the surface of the Earth for most of the length, however there are drag and sonic shock waves from hypersonic velocity at sea level.  These forces would tear both the craft and track apart.  Hence, to avoid this the track would be contained inside a vacuum tube with vents for air that is compressed in front of the spacecraft to escape.

The track would also be elevated to an altitude of 20 km (12 miles) to avoid several hundred g's of atmospheric drag associated with a track at sea level.  At 12 miles in height this would reduce the drag to around 3 g's.  There would be tethers to securely hold the track to the ground, while the same magnetic levitation would help keep the track that high.

Estimates are that it would cost around $60 billion and take 20 years to complete and is within the means of our current technology.  Compare this to the cost of developing and using rocket-based travel at more than $500 billion, world wide.  The Space Shuttle program cost around $170 billion and $150 billion for the International Space Station thus far.

Source:  Startram


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