'Star Trek' Technology for our 'Moon Colonies'

[Cymric]

It still puzzles me to a great extent how people can become so excited when they hear about the ion engine. Yes, it is a smart design. Yes, it is very energy efficient. Yes, it can propel spacecraft to very high velocities. But NO, it cannot provide a high accelaration: it took months for the probe to reach the Moon, and, adding insult to injury, used a gravity-assisted flyby of Earth!

Then there is a different problem: how do you brake a probe equipped with only an ion engine? Right now they used the Moon's own gravitational field to capture the probe. Gravitational fields of sufficient strength are rare :-).

It is a promising technology and deserves lots of further study, yes. But until an ion engine can deliver the same thrust that will propel us to the Moon in 4 days, and have the stamina to keep that same level of thrust up for years, then and only then will I begin to call it 'Star Trek' technology.

[Cymric]

PMC wrote:
Simple, rotate craft by 180 degrees and the thrust will eventually slow the probe down.  Okay it takes time to cancel out the velocities attained, but anyone who's ever played Frontier will understand the physics.  The Ion drive will have a very low thrust to weight ratio, therefore will take longer to accelerate/decellerate.

Yes, that's exactly what I'm getting at. If it takes a long time to accelerate, it takes an equally long time to decelerate as well. It would not do for a probe to overshoot its destination, and unlike Frontier, which has that marvellous bug/feature that braking is truly instantaneous when in ... err, what's that mode called, maximum time ignoration (for lack of a better word ;-)), the Real Thing obeys the laws of physics.

Every single interplanetary probe we've launched has had to rely upon the so called "slingshot" effect to accelerate / decelerate.  We're a long way from having the ability to fly around the solar system at will  a-la Frontier, but there is research into matter / anti-matter propulsion going on which may one day prove a viable proposition.

It's not that I'm against the idea of slingshots: we cannot do without them for the time being. It is just that the title of this thread ('Star Trek technology for our Moon colonies') is in my opinion a gross overestimation of what ESA achieved. It is a marvellous result, yes, but we haven't even come close to rivalling Star Trek yet.

[Cymric]

I don't know whether to laugh or cry, as it is at the same time outrageously funny and really, very much, without a shadow of a doubt, the truth.