January 13, 2014 – Today is moving day for my 29-year-old daughter who has purchased her own downtown condominium apartment. So in honor of her move I thought I would talk about a new propulsion system that NASA is considering for a future mission to Uranus. This new type of propulsion would take about the same time the Galileo Jupiter mission needed to reach its destination, a distance half that of Uranus. That’s certainly a bit farther than the 8 or so kilometers of my daughter’s trek, and she will get to her destination, once all packed up, in about 20 minutes.
Called the ESAIL or electric sail, I wrote about this technology a year ago. It is far different from conventional solar sails which use the pressure of photons of light to push a spacecraft. The ESAIL, on the other hand, converts light into an electrical charge. It does this by extending a lattice of wires away from the spacecraft to capture and convert individual photons to an electrical charge. The amount of acceleration remains small at 1 mm/s^2. Over time, however, the accumulated thrust will achieve a velocity approaching 20 kilometers (12 miles) per second. At that speed the spacecraft will reach Uranus in 6 years.
The Uranus spacecraft consists of three parts: the ESAIL with solar panels and tether reels with extension wires, the main body of the spacecraft with on board chemical propellant for adjusting the spacecraft trajectory, and a communications component to stay in touch through the Deep Space network with Earth tracking stations.
The ESAIL concept was first proposed in 2006 and has subsequently been developed by a team of Finnish engineers. It currently is being tested on an existing European Space Agency satellite, the ESTCube-1. A second test is planned for this year with the launch of the Aalto-1 communications satellite.
The proposed technology is described in a paper entitled Fast E-sail Uranus Entry Probe Mission.
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