Thanks, just curious ever since I watched Prometheus.
Electric propulsion has already been used in space. Ion thrusters were used for a spacecraft called Deep Space 1. A solar powered Hall effect thruster was used for the SMART-1 spacecraft.
The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) has been a hope for Mars exploration up to now.
However, there are newer plasma thrusters coming up:
Ion plasma thrusters are in some initial use on commercial geostationary satellites.
These birds have a 15 year service life, set in part by the limited on board fuel supply for the attitude control thrusters. Ion propulsion is much more fuel efficient (much higher Isp) ans thus very attractive, but reliability is still not as good as wanted.
Soviets have routinely been utilising ion thrusters on their satellites since 1972 so it is not new technology by any account.
I did some graduate work in collaboration with the Air force concerning the use of Ion plasma thrusters for satellites.
One of my professors does a lot of work on attitude adjustment and orbital stability of satellites using ion microthrusters.
A while give it 10-20 ish years for full scale practical deployment ( as in personnel transportation) , We have a long ways to go before we explore mars, infact i believe it would be a better idea to start on the moon and start working on a way to utilize he-3 as fule
Ion propulsion has already been used and is currently under development by a company in Surrey, UK (amongst others) and will be used for nanosatellites. In terms of manned spacecraft, nowhere near, associated electronics equipment may have to see further advancements before Ion thrusters are used for large scale satellites or certainly the scale they are in Prometheus (we've all thought it!). They aren't cost effective in comparison to other more developed thruster technologies.
Sincerely, The Jericho.
As mentioned, they are already used on geosynchronous satellites (made by http://www.boeing.com/defense-space/space/bss/factsheets/xips/xips.html [Broken], among others). These thrusters are very efficient (the ions are expelled at around 30,000 meters/sec), but can't throw out many particles per second (about a quarter of a milligram per second). The result is very weak (around 80 mN - the 165 mN spec is max, but normal operation is about 80 mN), but very efficient thrusters.
Of course, even weak thrusters will give you some acceleration and a very long acceleration will eventually get you a high velocity. But you'd really want more powerful thrusters if you wanted to accelerate a large spaceship reasonably quickly.
And a reliable source of electrical power. The particles are electromagnetically accelerated and the engines take a huge amount of electrical power (around 4500 Watts for 80 mN thrusters). With weak thrusters, large solar arrays, and being relatively close to the Sun, that's doable. (I'm not certain, but I think the reliability problems mentioned by etudiant had to do with strategies used to get more solar power per unit of area in order to keep the solar arrays from getting too big. I think the variations with the large, but traditional solar arrays are pretty reliable.)
For an interplanetary mission to somewhere like Pluto (or beyond), with an engine that's going to take humongous amounts of electrical power, you're going to need some other fuel-fed power source to supply electrical power to the engines, which somewhat negates the fuel efficiency achieved by accelerating the particles to such a high velocity.
There's no magic bullets. It takes energy to move a spaceship. If the energy is coming from somewhere else (the Sun), you're lucky in that you don't have to carry your fuel source around with you. If you have to supply the fuel for the energy you need, you wind up carrying around a lot of fuel no matter what method you use.
But nuclear energy at least provides a lot of energy for the amount of mass you're carrying around.
RTGs are pretty reliable and long-lasting, and might not go out of style until something "better" comes along. The Soviets used RTGs to power remote light-houses, etc, though there have been radiation-poisoning incidents when scrap-hunters have dismantled the equipment and the power-supplies for recyclable metals.
A new development to report in this area, still requiring much validation and testing.
If it works, the payoff could be a cheap, safe 30 day trip to Mars.
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