User:T.Neo/Manipulation of Phobos
Millions of years from now, Phobos will disentegrate due to tidal forces and form a planetary ring. However, Terraforming would increase atmospheric drag on Phobos, potentially causing it to collide with Mars. Moreover, Phobos is a problem to the construction of a space elevator.
One solution is to deorbit Phobos and allow it to collide with Mars. This might be achieved by colliding a small asteroid into it. The initial energy of the asteroid relative to the asteroid belt is 0. An initial kick is all that is needed to move the asteroid into a Phobos intersecting orbit. When Phobos impacts the surface it might release a large amount of water ice or carbon dioxide, and this could be a first stage of terraforming. Alternatively, Phobos could kick up large amounts of dust, preventing sunlight from hitting the surface.
Boosting into a higher orbit
Phobos could also be boosted into a higher orbit. Solar sails could be considered, but are probably too costly. A gravity tractor is a better idea, as it is not impeded by the rotation of Phobos. However, weather a thuster is a gravity tractor or surface based, it will likely not be powered by chemical rockets due to their inefficiency. An ion engine with sustained thrust over a long period of time could suffice. If there are volatiles inside phobos, such as water ice, they could be vaporised as propellant for a nuclear electric thruster. A mass driver could also be set up on the surface. Phobos it tidally locked to Mars, making it easier to build a surface thruster and negating the need for a gravity tractor.
Phobos boost mission
A spacecraft is launched from Earth to a transfer trajectory to Mars. It aerobrakes in the atmosphere and settles in orbit around Mars. It performs a rendezvous with Phobos. It locates a place to land, and drills several "tendrils" into the surface. It starts up either:
- An ion engine
- A nuclear ion enigine
- A VASIMR type engine, either solar of nuclar powered.
- A nuclear thermal engine.
The political implications of a nuclear reactor in space may be too much for some people to handle. A baseline mission should therefore use solar power. However, one idea could be a radioisotope rocket, using a Radioisotope Electric Generator, which has been flown to Mars before. Water ice could be mined from inside Phobos. This would increase the complexity of the mission, but it allows a solar thermal rocket to be used.
This continued thrust from any of the above slowly causes Phobos to spiral out from Mars. This will take a long time. Other spacecraft could come to refuel the original spacecraft. They would carry no propulsion unit, tendrils or survaying equipment like cameras. Even the first spacecraft will only carry small cameras to survay Phobos, and not the scientific equipment of robotic probes.
Another more productive method could be to "mine Phobos to nothing". However, if Phobos were to be mined to nothing as fast as possible, supply would quickly outstrip demand and there would be a surplus of raw materials with no place to be stored.
Space elevator anchor
This incorporates method No2. Phobos is positioned into an aerostationary orbit and used as an anchor for a space elevator. Carbon from Phobos could be used to produce carbon nanotubes for use in the elevator.