With its powerful analog to the great sailing ships of antiquity, the concept of solar sail propulsion has long been a catalyst of space advocates’ imagination and inspired such organization as the Space Regatta Consortium; a contemporary Russian-based program for the development of solar sail technology and the eventual establishment of a cislunar manned solar sail race. Such things may be quite possible by the time of Asgard but this form of propulsion will most likely find its most practical use in the Asgard context in unmanned spacecraft intended for specialized long duration missions.
Solar sails function by deploying vast ultralight structures to support radial reflective sails made from ultralight membranes –in the future likely made from extremely strong nanomembranes tensioned with nanofiber cables and supporting scales far larger and lighter than experimental solar sails today. The simple pressure of sunlight –or alternately a large powerful laser-, potentially large when collected over a large reflective surface, provides the propulsion. With its light-speed ISP, this propulsion has the potential to push objects to a high fraction of the speed of light, though the time to accumulate such speed is very great. These structures would be especially well suited to spacecraft based on the Beamship Concept of design, their core trusses providing a primary spar for the sail tension structures.
Magnetic sails are a recently devised variation on this concept that offers the advantage of exploiting very large virtual sail areas without the need for a large physical structure. Exploiting the solar wind’s stream of charged particles rather than light, the magnetic sail simply employs a powerful magnetic field generated by superconducting field coils as a virtual sail. Magnetic drag produced by the interaction of the sun’s charged particles produces the reactive force. With this a rather compact spacecraft can exploit a sail area of as much as a hundred kilometers in area, in some proposals, and vary its field strength linearly to control thrust. Like laser-driven sails, artificial sources of thrust for magnetic sails can be generated through the use of charged particle beams. However, since the solar wind is not as dense sunlight nor has as much ISP the magnetic sail needs a proportionally larger area to produce the same amount of thrust. And in order to function the magnetic sail must employ continuous electric power to its field coils, calling for nuclear energy or extremely large area solar collectors.
Another concept has emerged recently that may, however, offer a distinct advantage to the magnetic sail. Mini-Magnetospheric Plasma Propulsion or plasma sail employs plasma ejection in the magnetic field of a magnetic sail to effectively inflate it to even more vast areas. This allows a proportionally smaller basic magnetic field system to produce the same thrust potential as a much large system, which would make the necessary on-board power overhead of such systems much more tenable. This is likely to prove one of the more practical of solar sail technologies in the Asgard period.
Magnetic sails of both sorts could also –as proposed my Robert Zubrin the 1980s— become the basis of the first unmanned interstellar probes, magnetic sails serving as a magnetic brake or parachute once beyond the Sun’s heliopause and into the hydrogen based interstellar medium.
- Urban Tree Housing Concepts
- Asgard Digitial Infrastructure
- Carrier Pallets
- WristRocket Personal Mobility Unit
- RocShaw Personal Mobility Units
- Pallet Truck
- ZipLine Tether Transport System
- MagTrack Transport System
- SkyGarden and SkyFarm Systems
- Meat Culturing
- Microgravity Food Processors
- Pools and Baths in Orbit
- Plasma and Fusion Propulsion