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StarTram: The Maglev Launch Path to Very Low Cost, Very High Volume Launch to Space

J. Powell and G. Maise

Plus Ultra Technology

Abstract—Rocket based Earth to space launch systems are limited to a few hundred tons of payload annually at $~10,000 per kilogram. Over the past 30 years only marginal cost reductions have been achieved. Electromagnetic launch to space can greatly reduce launch cost and increase launch volume. StarTram uses superconducting maglev to accelerate heavy payloads ~20 to 30 tons, to orbital speed, ~8 kms/sec, in evacuated tunnels at ground level. Superconducting 20 ton Maglev passenger vehicles using the 1966 inventions of Powell and Danby now operate in Japan at 360 mph in the open atmosphere limited only by air drag. In evacuated tunnels, orbital speeds are possible. Two StarTram systems are described. The near term Gen-1 system launches 35 ton cargo craft from the surface at a high altitude location, e.g., ~4000 meters. The cargo craft ascends to orbit, where a small delta V rocket burn establishes orbit. Launch energy cost is only ~$0.50 per kilogram of payload. Adding costs of the cargo craft, operating personnel, and the amortized launch facility, total launch cost is only ~$50 per kg, compared to $10,000 per kg using rockets. A single Gen-1 facility can launch over 100,000 tons per year to orbit, 500 times current world capacity. Applications for the Gen-1 system includes greatly expanded Earth monitoring and communications, national defense, beamed power to Earth and robust space exploration. The Gen-1 system is described including Maglev levitation and propulsion, superconducting energy storage, the exit into the atmosphere, and the cargo craft design. Also described are the aerodynamic heating and deceleration forces on the cargo craft as it ascends to orbit. The initial deceleration is ~10 g and nose heating rate is ~20 kW/cm2. Both decrease to zero in a few seconds. Delta V loss through the atmosphere is about 500 meters/sec. Technology for the Gen-1 systems already exists and a Gen-1 facility could operate within 10 years. The U.S., Russia, China and Europe each have the technical capability and suitable high-altitude sites for a Gen-1 system. Potential sites are described. The Gen-2 StarTram system to launch both cargo and passengers is also described. It is a longer term, and requires a magnetically levitated launch tube to reach high altitude.

Keywords-Maglev, space launch, superconductors

I.I NTRODUCTION

Within the next few years, it is very likely that a new space race will begin, based on electrically powered Maglev launch to space. Maglev launch can reduce payload launch cost by a factor of 100 or more, and increase the amounts of payload launched by a factor of 100 or more. Space exploration and commerce have been greatly hampered by high launch costs into orbit and beyond. Placing a kilogram of payload into Low Earth Orbit (LEO) by rockets costs almost $10,000, while placing a human at the International Space Station costs 20 million dollars. Payloads to GEO cost an order of magnitude more, and to the moon and Mars, much greater still. Over the last 30 years, no realistic ways to substantially reduce launch costs, using chemical propellants, have been found. The energy cost to deliver payloads to orbit is tiny, if directly applied to the payload itself. At 8 kilometers per second, the kinetic energy of a kilogram is only 32 megajoule, 8.9 kilowatt hours. At 6 cents per KWH, this is 53 cents per kilogram, 10,000 times smaller than present launch costs. Using Maglev (Magnetic Levitation), heavy vehicles can be magnetically levitated above a guideway without mechanical contact or friction, and magnetically propelled at high speeds. Maglev systems are already operating in Japan (Table 1) and other countries for the transport of passengers, with levitation capabilities of hundreds of tons (1). Vehicle speeds of 360 mph have been achieved, with the only limit aerodynamic drag. In low pressure tunnels, vehicle speed is constrained only by guideway length and the vehicle acceleration capability.

TABLE I. J APANESE M AGLEV S YSTEM F EATURES AND C APABILITIES

StarTram is a completely new launch approach (2, 3, 4, 5). Magnetically levitated and propelled launch vehicles accelerate to orbital speed, ~8 km/sec, in evacuated tunnels. They enter the atmosphere at an elevated altitude and coast upwards to orbit. A small delta V burn by a small, low mass attached rocket engine inserts the StarTram craft into its final orbit (Figure 1). Two types of StarTram systems are possible (Table 2). The first generation system, termed Gen-1, is a high g cargo launch system. After reaching orbital speed, the Gen-1 cargo vehicle leaves the acceleration tunnel at a high altitude, but still at ground level, to coast up to orbit. As it travels Based on Powell-Danby Maglev inventions in 1960’s/70’s

Uses superconducting (SC) magnets on vehicle and normal aluminum loops on guideway

SC magnets induce currents in aluminum guideway loops to levitate moving

Levitation is automatic and inherently strongly stable in all directions

Vehicle is levitated 10 cm above guideway

Vehicle is magnetically propelled by AC current in Linear Synchronous Motor (LSM) windings on guideway

Vehicle speed controlled by AC frequency

Japanese Maglev System has demonstrated

Speeds up to 360 mph (limited by air drag)

Levitated multi-vehicle consists of ~200 metric tons

Carried over 50,000 passengers

Accumulated running distance >300,000 km

Japan plans 500 km Maglev route between Tokyo and Osaka to carry >100,000 passengers daily

978-1-4244-1833-6/08/$25.00 ?2008 IEEE1

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