The plasma magnet sail engine is little more than 2 pairs of charged rotating coils and is therefore extremely simple and inexpensive. A fully powered plasma magnet sail using a small nuclear power source could accelerate at 0.5G and reach 400-700 km/sec (0.2% of lightspeed) in half a day.
* Carrying a 10 Kilowatt power source enables very cheap missions to the Gravitational lens with trips taking 5 years. Multiple gravitational lens missions are needed since you can only observe what is on the exact opposite side of the sun from the gravitational lens mission
* 10kW power supply could propel a 2500 kg craft with an acceleration of 0.5g, reaching 400-700 km/s in just half a day. Greason suggested that with this acceleration, the FOCAL mission for gravitational lens telescopes requiring many craft should be achievable.
* A stream of charged particles could be generated from Phobos or Demos to slow the Plasma magnet sail to Mars. If you were slowing a 100-ton manned spacecraft, then you would need to produce 100,000 tons of particles. There would need to be multi-megawatt plant on the moons of Mars. It is possible to scale up for manned missions and to stop the craft.
* Neptune has a large enough magnetosphere where a plasma magnet sail could stop by decelerating at 5Gs. It would be a 4-month mission to Neptune
* a 10 KW system could slow an interstellar spacecraft from 20% of lightspeed over 2 years. Interstellar missions could then explore the target solar system.