My (now slightly edited) comment on https://phys.org/news/2019-09-europe-teaming-asteroid-deflection.html
“Nothing will work better than a nuclear device. Yet there are several entities who are pushing their “gravity tug” or other concepts and they have hijacked this train.”
However, the train has not left the station yet.
A human crewed Nuclear Pulse Propelled spaceship capable of interplanetary missions would necessarily carry a couple thousand “pulse units” (bombs). Those devices would be just as effective deflecting a rock as pushing a spaceship.
The Parker-Dyson-Spudis Continuum states only a kiloton range water shield can make Human Space Flight Beyond Earth and Lunar Orbit practical (Parker). Only a Nuclear Pulse Propulsion system can push such a shield around the solar system (Dyson). The Moon is the only place to acquire the water for shielding (Spudis), assemble, test, and launch nuclear missions.
The NASA Space Launch System is the only human-rated Super Heavy Lift Vehicle with an escape tower that makes launching fissile pits direct to the Moon an acceptable risk. SLS launch cadence needs to expand to 6 per year.”
The proposed “Space Force” is not about space at all, it is about Earth orbit and mostly about Low Earth Orbit. This NewSpace marketing technique of calling LEO space has always been a trick, a ruse, and it needs to end. Exploring LEO is not space exploration.
The best demarcation between space and Earth orbit is the distance where an object at the equator in a circular orbit will remain stationary over the surface. This is Geostationary Earth Orbit (GEO) at 22,236 miles up. Just as the ability to see out to the horizon originally determined where international waters begin, the minimal energy required to leave GEO makes this distance the ideal “edge of space.”
By this measure cislunar space, between the Earth and the Moon, would be comparable to “coastal waters” and GEO and the cislunar sea would properly be the domain of the space version of the Coast Guard. Call it the “Space Guard.” This could include a fleet of Lunar Cyclers flying around the Earth-Moon and providing a superhighway in space. The space counterpart to the Air Force would be the “Space Force” and would fly Beyond Earth and Lunar Orbit (BELO). If a space counterpart to the Navy is required there are always the ocean moons of the gas and ice giants and their subsurface seas to drive submarines around in.
A Space Force could serve the very useful purpose of removing nuclear weapons from Earth, a fantastic and impossible dream for many. The over a trillion dollars that is going to be spent in the coming decade on the U.S. nuclear deterrent makes relocating that arsenal to deep space not so fantastic or impossible. For over half a century the superpowers have been on hair-trigger alert and poised to launch on warning. There have been close calls. By placing the nuclear arsenals in deep space months away from Earth on human-crewed spaceships, we no longer face those few minutes to decide whether or not to destroy civilization. The other superpowers will follow America.
There are arguments against space-based-deterrence of course, but the pros, in my view, far outweigh the cons. One of those pros is a dinosaur killing rock will not be ending civilization while fleets of spaceships are on patrol ready to deflect any impact threat with nuclear devices.
Ice on the Moon 