Like the LightCraft, the Marine Mass Launcher represents another possible contender to the role space elevator, providing both an early system supporting better transit volume than the initial SE and, long-term, a contingency option for the development of a large volume system. The MML concept derives from Marshal Savage’s original Bifrost concept for a mass-accelerator launch system. Unfortunately, his original scheme for employing a mountain as a supporting structure for the system was unworkable owing to the extreme centrifugal forces the slope of the mountain would produce in a vehicle accelerated to hypersonic speeds. The MML presents a simple alternative in the form of a fully linear open-air accelerator that would be associated with an Aquarian marine colony. To overcome the obvious problem of air resistance for such an open-air accelerator, vehicles would be equipped with a laser-driven airspike which generates a thermal shockwave ahead of the vehicle, essentially blowing a hole in the atmosphere ahead and around the vehicle during its acceleration and launch trajectory, freeing it from air resistance. This, of course, would call for an exceptionally powerful portable laser system most likely powered by stored chemical reserves carried by each vehicle. The accelerator track would be responsible for all primary propulsion of the vehicle, which would exit the launch track at higher than orbital velocity and ‘coast’ into orbit unpowered. Consequently, this would be either an exceptionally long track or an exceptionally high-g accelerator –the latter being limited to bulk cargo applications. The system would likely be limited to LEO access.
Located on the Equator, the track system of the MML would be based on a pylon-buoy supported truss structure with an active straightening system. Designed to flex with some degree of freedom when not in use to minimize damage during inclement weather, the system would use a combination motor and Shape Memory Alloy alignment and tensioning system to rigidize its entire long length during an acceleration sequence. Designed generally as a light structure that would break apart easily in the event of launch failure, the leading end of the track would use a raised tubular track of closely-spaced field coils barely larger in diameter than its launch vehicle, transitioning to a series of wide, wide-spaced individual suspended hoops at the ejection end. A spiked texture on the exposed surfaces of the track structure would be used to discourage roosting birds –the launch vehicles moving so much faster than sound that their shockwave would vaporize birds before they could even hear what was coming. This track configuration is necessary because in order to employ an airspike, the vehicle must move completely independently of any other component of the track and be wholly contained by its airspike shockwave. Systems where a vehicle uses some sort of accelerator ‘keel’ or ‘rail’ would not be able to reach hypersonic velocities as the keel –being outside of shockwave shielding– would not withstand air resistance.
Consequently, the design of vehicles used by the MML would favor the use of simple capsules with conical ends or open space frame accelerator cradles (the strict need streamlining is precluded by the use of the airspike) that could be carried as part of a vehicle to orbit or could be discarded (and likely destroyed) upon ejection. Capsule vehicles would employ the simple approach of ballistic reentry using a heat-shield cap on their aft-end and parachute assisted splashdown. This would also accommodate, with a very large-scale system, the use of reusable waverider type reentry glider vehicles as Marshal Savage envisioned. However, the possible use of the airspike as a reentry shield offers the possibility of a system that can employ a second MML track as a vehicle capture system, allowing reusable capsule vehicles to be returned right to the point of launch. Combining laser modulation profiling of the airspike shockwave as a means of limited steering with retro-rocket attitude control, it might be possible to allow a capsule vehicle decelerating from orbit to maintain a horizontal attitude along a very long reentry trajectory. The vehicle would then be captured by an even longer MML track that decelerates it and returns it to a vehicle service facility, thus providing almost railway-like travel to and from space. This would require a very sophisticated and compact energy storage system for extremely reliable lasers –perhaps limiting this possibility to some time in the Solaria phase of space development.
Obviously, a man-rated MML system or one on a scale of the original planned Bifrost launcher could ultimately be one of the largest built structures in the history of civilization and would likely only be pursued as an alternative to the Aquarian Space Elevator, should it prove, over time, impractical. But this offers an important contingency option for electric powered launch capability.
- Mountain Waverider
- UltraLight SSTO
- Bifrost Space Elevator
- Bifrost Support Systems