Riding an Ion Drive to the Asteroid Belt

Iron Condor writes "JPL is now close to embarking on another of its trademark, one-of-a-kind missions, this time to the heart of the asteroid belt: The Dawn mission is being prepared for launch this summer from Kennedy Space Center. Dawn will explore Ceres and Vesta, the two largest known asteroids in our solar system, which lie in the vast expanse between Mars and Jupiter. In the process, the mission will make history on several fronts. Besides being the first spacecraft to orbit a main-belt asteroid and the first to ever orbit two targets after leaving Earth, Dawn will be the first science mission powered by electric ion propulsion, the world's most advanced and efficient space propulsion technology."

Comments

acceleration with patience

[one_who_uses_unix]

I enjoyed the article - take a look at the FAQ. The author(s) mention that ION drive is "acceleration with patience" - it will take 6 years of accelerate to change the spacecraft's velocity by 10KM/s but will use a fraction of the weight of propellant that conventional chemical propulsion would.

Space exploration and the related technology are still in their infancy, it is really exciting to to see the stuff of decades old sci-fi making into reality. Who can predict what non-conventional propulsion systems will look like in 50 years?

Re:acceleration with patience

[arivanov]

Solar sail will be one of them. Various forms of nuclear drive - another.

Re:acceleration with patience

[morgan_greywolf]

I'll take a stab.

Propulsion systems will likely be driven by some sort of nuclear energy. The theory of operation of these systems will probably revolve around some set of quantum effects, maybe even superposition. These will be early systems based on this technology and, as such, may be prone to various difficulties imposed by the limits of an unrefined technology. They will be capable of traveling at unprecedented speeds using amazingly small amounts of fuel.

While there will definitely be privately-funded space travel, systems based on these new technologies will be very costly, and thus will only be in use by government space agencies around the world. The key to developing these new technologies will be international colloboration, most likely between Japan, Europe, the United States, Canada and possibly India and China.

How's that?

Re:acceleration with patience

[JudgeSlash]

I'm voting for VASIMR (variable specific impulse magnetoplasma rocket). They are meant to be able to "change gears" from high thrust, low specific impulse to low thrust, high specific impulse and vice-versa. In theory you could use the same engine to climb out of Earth's gravity well, coast on the flat space-time bits inbetween, and then come wail on those pesky martians from the top of their gravity well. Suckers.

http://en.wikipedia.org/wiki/Variable_specific_imp ulse_magnetoplasma_rocket

Two targets?

[Atheose]

One thing that surprised me was the fact that it will be the first spacecraft to orbit two seperate targets after launch. For some reason I did not think that this was a difficult thing to do, though now that it has been brought to my attention I can understand why.

Screw that, we need nuclear propulsion.

[Dr. Manhattan]

This one for liftoff from Earth (exhaust is not radioactive), and in-system work, and this one for deep-space missions. We can move thousands of tons around with these, cheaply and safely. (Note: neither of these is an Orion type, which is another option.)

Re:"Electric ions"?

[MyLongNickName]

Ummmmm... by definition ions require some type of propellant. There are thoughts on some kind of mass driver that would take advantage of the sparsely populated atoms in space for thrust, but nothing past the drawing boards as far as I know.

That being said, ion drives are many, many times more efficient than traditional chemical propellants. If my memory serves, about 3 orders of magnitude more efficient. This yields a much smaller propellant tank. Especially when you consider that the tanks must also be dragged around.

Stairway to heaven

[Nefarious Wheel]

Propulsion systems will likely be driven by some sort of nuclear energy

Every once in a while I drift back to Doc Smith on the bookshelf. Although his space suits were made of Bakelite, some of his thoughts were rather far-seeing (thinking for example of the replicated logic units of his Skylark electronic brain) considering he wrote in the 30's, where Einstein's mass-energy equation hadn't yet been popularised. Pre-atomic era. He thought that with enough energy you could turn energy directly into matter and use that for reaction mass. Sturgeon's Law holds with his ideas, for sure, but still it really makes me wonder...

Re:Not the first ion thruster propelled spacecraft

[Brett Buck]

>To my knowledge, all previous missions
>involving ion propulsion have been for
>the purpose of testing ion drives,
>while this one is expected to perform
>scientific exploration and happens to
>use an ion drive.

      Not even that; The Russians have been using them for decades for various spacecraft, and at least some current US comsats use them as well. I am working on another one right now, a comsat that uses it for orbit raising and on-orbit stationkeeping/repositioning.

      I read TFA and it's mostly a load. I don't see why JPL has to jump on the same "we did it first" (except for all the other people who did it before us) bandwagon. I expect that sort of nonsense from ESA but JPL shouldn't have to pump themselves up, since they actually did do a lot of legitimate "firsts".

          Brett

            Brett

Firsts-O-Matic

[Tablizer]

I believe you could make a distinction between science and technology missions.

But they are slicing thin to create new "firsts" in general. Being the first to orbit asteroids in the *main belt* is also kind of a yawner because Eros, outside the belt, was also orbited IIRC. Being inside the belt is almost like saying, "Pioneer X is the first probe to pass Jupiter while Earth was between a 30 and 50 degrees angle relative to the Sun". It is easy to make up records and firsts if you combine enough factors. Sports announcers do similar stuff: "Dribbley Dunkor was the first point-guard over 6-foot-4-inches to score more than 25 points with a broken big toe before the all-star break!"