The difference between ion propulsion and conventional propulsion is that in ion propulsion you are throwing little tiny amounts of stuff out the back at very high speeds but in conventional propulsion you are throwing huge amounts of stuff out the back at a slower speed. Does that fact alone stop us from using ion propulsion on Earth? No, because you can speed up accelerate the little mass enough to produce enough force.
The problem of getting a rocket into space is a different problem which engineers call power density. Power density is the amount of power an engine has divided by the weight of the engine. Other sources of thrust such as a chemical rocket or solar sail are not considered because they do not meet the criteria needed.
Chemical rockets have a very low I sp compared to the alternatives. Solar sails are impractical because they would require Giga- or Terrawatt lasers continuously shining from Earth at a solar sail on the order of kilometers in diameter attached to the satellite.
To minimize mass, this sail would be very delicate and would probably not survive the trip through space intact. Based upon this information, an ion thruster has been selected as the primary propulsion system for this expedition. Trajectory Overview.
The orbit will be such that Earth can be used as a gravitational slingshot to reach Jupiter. Once the slingshot past Earth is made, the ion thruster will be enabled. Jupiter will then be used to gain more velocity relative to the Sun by using it as a gravitational slingshot to escape the solar system at a velocity of This phase of the journey will take roughly 5 years. During this period, power from the RTG will occasionally be diverted to a star tracking system to determine the position of the satellite in space and verify its trajectory toward Epsilon Eridani.
Over the course of the years, the spacecraft should be oriented on a trajectory accurate enough to reach Epsilon Eridani. The trajectory used for the voyage at this stage will have been precalculated on Earth to account for the motion of the stars and hypothesized solar winds and particle densities in deep space.
This generator will be used to generate a small neutron source, possibly by accelerating alpha particles into beryllium, capable of initiating fission in a small reactor. Once this reactor is on, it will be able to power the electronics used for star tracking and power the ion drive. Its power output will be moderated by boron control rods. We had to make hundreds of changes.
The breakthrough offers a great proof of concept showing ion thrusters can be used on Earth, says Alec Gallimore, an aerospace engineer at the University of Michigan who was not involved with the work. But any such use would likely be in limited capacities. Propellers and jets are still far more efficient than the ion wind thrusters Barrett demonstrated, making it unlikely that passenger planes would switch over anytime soon.
Or, Barrett adds, drones used for deliveries, filming or environmental monitoring. But this is silent. Already a subscriber?
Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. A thruster that's being developed for a future NASA mission to Mars broke several records during recent tests, suggesting that the technology is on track to take humans to the Red Planet within the next 20 years, project team members said.
Air Force, is a Hall thruster — a system that propels spacecraft by accelerating a stream of electrically charged atoms, known as ions. In the recent demonstration conducted at NASA's Glenn Research Center in Ohio, the X3 broke records for the maximum power output, thrust and operating current achieved by a Hall thruster to date, according to the research team at the University of Michigan and representatives from NASA.
It generated 5. The previous record was 3. Hall thrusters and other types of ion engines use electricity usually generated by solar panels to expel plasma — a gas-like cloud of charged particles — out a nozzle, thus generating thrust. This technique can propel spacecraft to much greater speeds than chemical propulsion rockets can, according to NASA. That's why researchers are so interested in ion propulsion's potential application for long-distance space travel.
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