Author Topic: Scientist's Laser Engine May Revolutionize Space Travel  (Read 7446 times)

Offline marsavian

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 3216
  • Liked: 2
  • Likes Given: 3

Offline tmckinley

  • Regular
  • Member
  • Posts: 86
  • Liked: 0
  • Likes Given: 0
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #1 on: 09/23/2007 10:34 pm »
"The project was built on a very small budget and its accomplishments have helped it secure funding from a prestigious Phase II NIAC grant (NASA Institute for Advanced Concepts), which funds only the most revolutionary ideas for the next generation NASA space missions."
-Wasn't the NIAC closed last month? I realize that obviously this funding happened before then, but I wonder what future projects will be sacrificed?

Offline wannamoonbase

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 5412
  • Denver, CO
    • U.S. Metric Association
  • Liked: 3112
  • Likes Given: 3861
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #2 on: 09/23/2007 11:02 pm »
Interesting too bad they closed NIAC to get Constellation started.  hopefully after the STS and ISS madness is over they reopen it.

Edit: I believe proof is in the flight.  Would like to see some of these wonder technologies fly to see if there is anything to them.  If they don't pass the smell test to get a test flight than either there isn't much to it, or its so far out there that I will be very old or dead before we see it fly.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #3 on: 09/23/2007 11:48 pm »
It will not revolutionize anything.
"Paper planes do fly much better than paper spacecrafts."

Offline Delta Manager

  • Full Member
  • *
  • Posts: 106
  • Liked: 0
  • Likes Given: 0
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #4 on: 09/24/2007 04:52 am »
Quote
sandrot - 23/9/2007  6:48 PM

It will not revolutionize anything.

There seems to be one of these claims every month at the moment, doesn't there.

Offline khallow

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 1954
  • Liked: 8
  • Likes Given: 4
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #5 on: 09/25/2007 05:59 pm »
I see problems here. If I understand correctly, the propulsive force is between the two mirrors (one which would presumably be fixed to a large object like the Moon). So the beam can only bounce back and forth multiple times as long as the mirrors are close, relative to their size (radius). Get too far away and most of the photons will missi the target much less bounce multiple times. Heating of the mirrors probably is a problem. The mirrors need to reflect almost perfectly a small range of frequencies since photons lose some energy and become lower in frequency as they bounce off of an accelerating target.
Karl Hallowell

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #6 on: 09/25/2007 06:05 pm »
Also the other "promising" development is not so promising. You can't really position a swarm of satellites, unless it will be proven that laser can work as a tractor beam... you can push further away satellites but you can't bring them together if not by other means... so what's the point of having a laser, after all?
"Paper planes do fly much better than paper spacecrafts."

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3067
  • Where Be Dragons
  • Liked: 5
  • Likes Given: 3
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #7 on: 09/25/2007 06:53 pm »
It's been covered here before, search the old thread.

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #8 on: 09/25/2007 07:05 pm »
Quote
meiza - 25/9/2007  2:53 PM

It's been covered here before, search the old thread.

Please provide a link.
"Paper planes do fly much better than paper spacecrafts."

Offline hyper_snyper

  • Elite Veteran
  • Full Member
  • ****
  • Posts: 728
  • Liked: 1
  • Likes Given: 22
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #9 on: 09/25/2007 07:15 pm »
Quote
sandrot - 25/9/2007  3:05 PM

Quote
meiza - 25/9/2007  2:53 PM

It's been covered here before, search the old thread.

Please provide a link.

http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=9794&posts=15

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3067
  • Where Be Dragons
  • Liked: 5
  • Likes Given: 3
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #10 on: 09/25/2007 07:17 pm »
Quote
sandrot - 25/9/2007  8:05 PM

Quote
meiza - 25/9/2007  2:53 PM

It's been covered here before, search the old thread.

Please provide a link.

I'm not working for you and am not a moderator either, but I'll make an exception this time:
http://forum.nasaspaceflight.com/forums/thread-view.asp?tid=9794&start=1&posts=15&highlight=laser+thruster&highlightmode=1
Simple terms laser thruster found it, I suggest using search yourself.

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #11 on: 09/25/2007 07:20 pm »
It was just a courtesy I was asking for. English is not my mother language and searches don't always end up with what I am looking for.
"Paper planes do fly much better than paper spacecrafts."

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3067
  • Where Be Dragons
  • Liked: 5
  • Likes Given: 3
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #12 on: 09/25/2007 07:22 pm »
Okay, sorry to lash out like that, no bad feelings. :)

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #13 on: 09/25/2007 07:33 pm »
No problem... with all the British/US/Australian fellows, don't forget of us aliens... ;)

So, I was looking the old thread, and there is little hint on how laser can be helpful for formation keeping. In my very limited mind laser can only help for ranging.
"Paper planes do fly much better than paper spacecrafts."

Offline meiza

  • Expert
  • Senior Member
  • *****
  • Posts: 3067
  • Where Be Dragons
  • Liked: 5
  • Likes Given: 3
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #14 on: 09/26/2007 12:09 pm »
It's the photon pressure. You put the lasing medium / amplifier between two mirrors. Then the light pressure pushes the mirrors apart. Put one mirror and the lasing medium in your own spacecraft and the other mirror in a remote spacecraft and you can push the two away from each other. It's a very small force from one photon bounce but the trick is to use very good mirrors so the light bounces back and forth many times. Still the force is very small. But it could in theory be very precisely controlled and used if you have optical telescopes formation flying in space and combining their light. You wouldn't need to expend propellants or worry about exhausts contaminating optics either. The disturbing forces are very small too (light pressure from the sun for example) so the light thrusters could perhaps cope with that.
The force is so small compared to the energy used that it's not useful for anything where a lot of acceleration is needed.

This is all "as far as I know" and "if I remember correctly". :)

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #15 on: 09/26/2007 01:02 pm »
The photon pressure can be experimented... At the physics laboratory, when in high school, we had a glass bell with a little propeller inside. one face of the blades was white, the other one was black. If you left it in sunlight the propeller would start to spin.

Still, the effect you are explaining, would separate the nanosatellites, and cannot bring them together. Even in case we want to take advantage of the laser only for separating... once you get the nanosatellites started, you need to stop them.
"Paper planes do fly much better than paper spacecrafts."

Offline Tom Ligon

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 536
  • Manassas, VA
    • Tom Ligon's Website
  • Liked: 1
  • Likes Given: 0
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #16 on: 09/26/2007 01:14 pm »
Ah, the infamous vane radiometer!  Did you, perchance, notice which way it turned, as compared to which vane surface was black versus which was reflective?

I believe that device actually turns away from the black surface, not the reflective!  And it will do so only if there is a trace of gas in the vacuum bottle.  They don't work in a hard vacuum. They actually work by heating rarified gas, not by photon recoil.  

This is an example of how careful you must be in experiments that purport to demonstrate feeble forces.  In the case of a laser, the forces in the electrical power leads interacting with each other and Earth's field, and factors such as heating gas in the chamber, could easily exceed the photon thrust if you do not take care in the experiment.

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #17 on: 09/26/2007 01:31 pm »
Oh, no! I was fooled by my teacher!!! :)

I can't recall which way it was turning, it was a good 24 years ago.

You may be very well right that vacuum was not that hard.
"Paper planes do fly much better than paper spacecrafts."

Offline Tom Ligon

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 536
  • Manassas, VA
    • Tom Ligon's Website
  • Liked: 1
  • Likes Given: 0
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #18 on: 09/26/2007 02:58 pm »
I've seen them in Spencer's Gifts, and Edmund Scientific usually carries them.  Keep and eye out and you will probably come across one again.

The most impressive laser propulsion test I have seen shot a ground-based laser at the bottom of a lightweight disk, which shot up like a rocket for several meters, until it drifted out of the beam.  It worked by superheating and ablating material on the bottom of the disk.  Firing a powerful laser at a mirror that is not perfectly reflective would likely have a similar effect contributing to the thrust.  If it started to darken the mirror, no doubt the contribution to thrust by heat would rapidly increase.

Offline sandrot

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 751
  • Motown
  • Liked: 9
  • Likes Given: 5
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #19 on: 09/26/2007 03:15 pm »
I've been working on an industrial laser robot and I can say that the choice of coating for mirror and mirror cooling are paramount, if you want to keep the robot working. Also, mirror must stay clean, so laser pressure doesn't go well on spacecrafts that have also other propulsion means. Exhaust impingement would kill the mirror.
"Paper planes do fly much better than paper spacecrafts."

Offline Tom Ligon

  • Extreme Veteran
  • Full Member
  • ****
  • Posts: 536
  • Manassas, VA
    • Tom Ligon's Website
  • Liked: 1
  • Likes Given: 0
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #20 on: 09/26/2007 05:11 pm »
Here's the Edmund ad for a particularly pretty model.  This ad actually correctly explains the motion.  Most previous ads I've seen are for a cheaper clear-bulb model and suggest the effect is due to photon pressure.

http://scientificsonline.com/product.asp?pn=3116001&bhcd2=1190825767

There is no reason a vane radiometer would not turn by photon reflection if it had a sufficiently strong light source and did not have the competing hot gas effect.  If you have access to a sufficiently powerful laser, it should be possible to target the reflective surfaces and make it spin, but the force will be really dainty in comparison to what makes the one above move.

Something like a gold-leaf electroscope, which bounces a laser between two opposing mirrors multiple times, might make the more definitive demonstration.  That is essentially the principle of this "laser engine".  It would make a neat science project, but I think the value as a space propulsion technology is quite a stretch, to put it politely.  

It might have some use for launching really lightweight things from Luna, but I don't know what the "things" would be good for.  Radar reflecting targets, perhaps?  Or maybe launching solar sails from the lunar surface?  The "thing" would have to get up to speed before the aiming problem got to be a limitation, and that probably means no more than a few thousand km or so, if even that.


Offline CriX

  • Regular
  • Full Member
  • *
  • Posts: 186
  • Lake Forest, CA
  • Liked: 27
  • Likes Given: 86
Re: Scientist's Laser Engine May Revolutionize Space Travel
« Reply #21 on: 09/26/2007 08:46 pm »
The AIAA paper says ~1mN per 10watts.  It could be scaled up.

Tags:
 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1