Lifter Technology

space_psibrain · 2003-07-25 18:04:59

This is a new way to get around mars, without having to worry about many moving parts or such...given that a mars plane would be unwieldy...this might be a better alternative

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sethmckiness · 2003-07-27 05:30:15

It seems interesting.. But I am somewhat skeptical due to the vagueness and attitude of the site. Am I the only one that feels this way?

Josh Cryer · 2003-07-27 21:21:08

NASA pretty much debunked the lifter myth. The main problem with them is that they require ungodly ammounts of electricity to do anything remotely useful.

space_psibrain · 2003-07-28 01:31:42

perhaps within a span of 50 years or so...i mean the technology was patented in the 1950s, so perhaps by then...

Shaun Barrett · 2003-07-30 06:40:45

I've never really looked into these 'lifters', as they call them, and I don't want to sift through miles of text checking them out.
Can anyone give me the low-down on these things in a nutshell?

For instance, the ones they fly in labs: They are connected to a power supply with a wire, right? Even so, what is the physics behind their levitation?

Thanks ahead!

Adrian · 2003-08-12 03:26:35

Here's an article on Wired that debunks lifter technology, at least in the 'antigravity' sense.

space_psibrain · 2003-08-15 18:55:27

yes, yes, I already knew about the ion wind phenomena...and if i'm not mistaken, the article also mentions it possibly being useful for

Martian gliders

Shaun Barrett · 2003-08-18 20:37:32

Thanks, Adrian, for the interesting link about lifters. Looks like they're just a form of electrical helicopter!

Dicktice, I did see the New Scientist article you mention. It was some time ago now so I don't remember all the details.
I forget the name of the scientist who maintains a mirror light sail won't move, but common sense seems to tell me he's wrong. A mirror sail should be the most effective form of light sail, since it maximises the proportion of photons doing a complete 'about face' and minimises the number being absorbed. To my way of thinking, a reflected photon whose momentum is flipped from +1 to -1 is contributing twice as much momentum to the sail as a photon which is absorbed and has its momentum changed from +1 to zero. It's just arithmetic!

As for the doppler effect, at the kind of velocities we're talking about within our solar system, any such effect will be vanishingly small.
However, if our light sail is getting faster as it moves away from the light source, the apparent wavelength of photons falling on its surface must be getting longer. If the wavelength is increasing, the frequency must, by definition, be decreasing. Since the energy of a photon is proportional to its frequency, the faster the light sail goes, the less energy each photon impact imparts to the sail.
As a result, the rate of acceleration of the sail should decrease as the sail moves ever faster, not increase.

This Doppler effect, though, as I've mentioned, will be unimportant unless we're talking about speeds which are a significant fraction of light speed. Within our solar system, it seems to me that a light sail, with its vast area and relatively low mass, will start to experience noticeable 'atmospheric drag' due to interplanetary gas density long before the Doppler effect becomes a problem.
But it is an interesting theoretical problem just the same. And with the imminent launch of The Planetary Society's Cosmos 1 solar sail, we may soon have actual data to work with and be in a position to dispense with the hypothesising and start dealing with facts!

space_psibrain · 2003-08-21 21:43:10

the launch of Cosmos 1 should indeed be interesting...

Shaun Barrett · 2003-08-23 07:51:32

Hi Dicktice!
I went off looking for the equation for the momentum of a photon, so as to place my previous answer about solar sails on a firmer mathematical footing.
But now I notice your original question has disappeared.

I assume you've lost interest in solar sailing or have decided to wait and see how well (or otherwise! ) Cosmos 1 performs!

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#1 2003-07-25 18:04:59

Re: Lifter Technology

#2 2003-07-27 05:30:15

Re: Lifter Technology

#3 2003-07-27 21:21:08

Re: Lifter Technology

#4 2003-07-28 01:31:42

Re: Lifter Technology

#5 2003-07-30 06:40:45

Re: Lifter Technology

#6 2003-08-12 03:26:35

Re: Lifter Technology

#7 2003-08-15 18:55:27

Re: Lifter Technology

#8 2003-08-18 20:37:32

Re: Lifter Technology

#9 2003-08-21 21:43:10

Re: Lifter Technology

#10 2003-08-23 07:51:32

Re: Lifter Technology

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