Electric drives for surface to space travel - are there any?

Gibbon · 2002-09-01 05:13:54

So, as the topic asks, are there any electric drives that would work for surface to space flight and what are the approximate payloads that could be carried with them?

If there are any that can take large payloads, perhaps an investment in creating a fusion (or is it fission) reactor on the moon would be in order. The idea is that the energy is beamed directly to the ship as it is flying, therefore it doesn't have to carry any fuel and there is no danger of nuclear explosion from an engine or whatever.

Anyway, maybe the question could be answered.

Mark S · 2002-09-01 07:56:50

Thus far, we can't use electric drives for ground-launching spacecraft. Our problem is that these engines produce very small amounts of thrust. For example, the VASIMR test engine could barely lift a hummingbird!

Electric drives are handy once you get to orbit. With very little atmospheric drag and no gravity to fight, the engine can operate continuously and move the ship at a slow and steady pace. The acceleration will be slow but fuel is used more efficiently.

Shaun Barrett · 2002-09-03 05:04:52

Hi Gibbon!
Even if you could beam energy to your spacecraft so that no fuel, as such, is required, you will still need some material to use as reaction mass. i.e. You still need something with mass that can be thrown backwards in order for the spacecraft to go forwards.
In a way, this places almost as much of a constraint on the craft as does the requirement for fuel. This is because you can run out of reaction mass in much the same way as you can run out of fuel itself!
You're either going to need a gas station or a mass station!!

P.S. Hence the current search for a propellantless propulsion
system.
Which reminds me ... has anyone heard anything about
NASA's test program with the Podkletnov gravity device?

Phobos · 2002-09-03 19:35:12

In a way, this places almost as much of a constraint on the craft as does the requirement for fuel. This is because you can run out of reaction mass in much the same way as you can run out of fuel itself!

Are they still doing experiments on that laser launched vehicle where they vaporized inert elements like water to achieve lift? Lasers seem to be playing a big part in advanced propulsion schemes lately, they're being used in everything from light sails to space elevators. I'm kind of surprised by it considering it's just light.

Tom Jolly · 2002-10-22 08:27:53

The only "electric drive" (besides the ion stuff which is way underpowered for the purpose) I can think of which could get to orbit is a mass driver; a bunch of earth-mounted coils to toss a mass into space at 9+ KPS (you lose about 2 KPS passing through the atmosphere and fighting the first 150 miles of gravity). There's also the slingatron and variations on it, but I think the mass driver might be less technically challenging (albeit over 20 miles long and danged expensive). Of course, you'd kill anyone that was stupid enough to go as a payload.

There was a brief thingy with someone trying to get government funding to use polar ions as a propulsion source, but that fell apart when somebody came along and told the stupid politician that it wouldn't work and that he was just being milked for money. Theoretically, you could use the earth's magnetic field to propel yourself; unfortunately, the field you would have to generate would be incredible huge, and the mass you would need to generate such a field would be a hundred times larger than the force from the field. So, that's a wash, too.

The only viable "purely electric" system I can think of that can launch a man is Myrabo's lightcraft, using ground-based lasers and the atmosphere as a propellant.

Shaun Barrett · 2002-10-22 20:07:17

Hi Tom!

There's a discussion about rail guns going on over at "Mass Drivers on Mars".
Your information about atmospheric drag might be useful as that seems to be the 'sticking point' at the moment!

Care to join in?

TJohn · 2002-10-23 06:39:53

Quote: Thus far, we can't use electric drives for ground-launching spacecraft. Our problem is that these engines produce very small amounts of thrust. For example, the VASIMR test engine could barely lift a hummingbird!

Electric drives are handy once you get to orbit. With very little atmospheric drag and no gravity to fight, the engine can operate continuously and move the ship at a slow and steady pace. The acceleration will be slow but fuel is used more efficiently.

Mark, how long would it take to get to Mars? Would using the ideas of the Mars Direct or even RobS' idea plus electric propulsion be a viable way to get to Mars with current technology?

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#1 2002-09-01 05:13:54

Re: Electric drives for surface to space travel - are there any?

#2 2002-09-01 07:56:50

Re: Electric drives for surface to space travel - are there any?

#3 2002-09-03 05:04:52

Re: Electric drives for surface to space travel - are there any?

#4 2002-09-03 19:35:12

Re: Electric drives for surface to space travel - are there any?

#5 2002-10-22 08:27:53

Re: Electric drives for surface to space travel - are there any?

#6 2002-10-22 20:07:17

Re: Electric drives for surface to space travel - are there any?

#7 2002-10-23 06:39:53

Re: Electric drives for surface to space travel - are there any?

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