UNMANNED SPACE CONCEPTS
Pluto, the Kuiper Belt and Beyond!
Pluto Trans-Rapide Background
This was a concept I developed for an ion-engined, true microspacecraft to race the Pluto Express Spacecraft to the planet Pluto, inspired by the pioneering work of the father of UK ion propulsion, the late Dr David Fearn. NASA's Pluto Express subsequently got cancelled, then re-emerged to limp on in various forms, finally being realised in the New Horizons spacecraft. I still personally believe NASA should have gone with an ion engine powered spacecraft, at least a solar powered ion engine propulsion section for use in the inner solar system to get a Pluto spacecraft up to speed.
Pluto Trans-Rapide - the concept
Pluto Trans Rapide was designed to be exceptionally small, and to rely on the least amount of power for the radio transmitter possible. The purpose of packaging the spacecraft in a very small form factor was to reduce the requirement for large escape motors to give the vehicle its initial impulse, and thus to reduce the size of the launch vehicle required, thus reducing the overall mission costs.
Subsequent NASA sponsored studies have produced the Innovative Interstellar Explorer Mission, which would send an ion engined probe out to a distance of beyond 100 Astronomical Units. This study seems to follow on from previous work on the Thousand Astronomical Unit (TAU) space probe that was previously studied.
Current ion engine propelled spacecraft
Ion engines are finally, slowly catching on as a very effective propulsion system for interplanetary and deep space spacecraft. The NASA Deep Space 1 spacecraft, the NASA Dawn spacecraft, the Japanese Hayabusa spacecraft, the European SMART-1 spacecraft and more recently the NASA New Horizons spacecraft to Pluto, all use ion engines for propulsion. The European Space Agency Bepi-Colombo mission to Mercury will also use ion engines for propulsion.