Topic awaiting preservation: Solar sail, space propulsion system is tested in Ohio lab.

Ohio Lab Tests Space Propulsion System

Until I read this article I did not realised this propulsion system would render useless the springshot around stellar objects. Cool.
One thing I don't get yet, considering the incredible speed the craft could reach, how would it brake efficiently ?



(Edited by poi on 05-05-2005 17:56)

ooh exciting stuff! We'll be able to get REALLY lost now!

Cool stuff! Thaqnks for posting.

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One thing I don't get yet, considering the incredible speed the craft could reach, how would it brake efficiently ?

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Changing the sail's angle to the sun would allow the craft to slow down or speed up.

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By the same method it uses to speed up.

Sure but the deceleration speed would be more or less equal to the acceleration speed. So in case of emergency, i.e. an small stellar object comes close, an accident, an attack of UFOs , ... there's no real way to brake on a short distance. Is there ? It might also take some time to deviate the direction of the craft and avoid an impact.

The craft should probably have a more conventionnal propulsion system for such cases.


[edit] making my point clearer (hopefully) [/edit]

(Edited by poi on 05-05-2005 18:28)

I imagine they'll use ordinary fuel and thrusters for just such an occasion, the nice thing is that with the sails they won't need the same amounts as they do currently, so it'll work out much much cheaper.



(Edited by Blaise on 05-05-2005 18:24)

If they are next to a planetary body they can areo-brake by skipping / skimming the atmosphere. Of course with this you need your calculations to be spot on, or you run the risk of accelerating the craft and tossing it out of the system.

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First missions -- scientific payloads of a few hundred pounds -- are likely to be to the inner planets, Venus and Mercury, and to the sun.

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OK, if "streams of solar energy particles" are streaming out from the sun to push this sail, how are they going to get it to go TOWARD the sun???

briggl, they'll use a mirror of course

/Dan

{cell 260} {Blog}
-{ ?There are two major products that come out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence. - Jeremy S. Anderson" }-

Dan I am a little confused by your statements on the mirror.



The sail has to be much larger that the payload, so I can imagine where you could put a mirror on the payload so that it would be able to reflect the light into the sail.

You could put a hole in the middle of the sail on then have a mirror on the payload that directs the photons back to the sail.

At anyrate you would need on side of the material to be highly reflective so that the light directed towards the sail would not turn it arround.

The other thought I had on this would be that a focusing reflecting mirror could be put on say the moon, and then photons could be reflected back towards the sail, but I can't imagine this being very effective at all.

Dan @ Code Town

They could also adjust the sail position and course like a sailboat does now. Tack against the wind.

Instead of a system of mirrors I think the sail could work on both side, and a mechanism occludes one side or the other. Ok the sun is the closest star but the billions of other stars though way further could do the the trick when the sail do not face the sun.

FWIW, here comes an illustration of sailboat navigation :





(Edited by poi on 05-06-2005 15:31)

Thanks that is a bit better an illustration. I think that clears a bit up, I don't understand it completely yet, I might have to do some more research on this.

Thanks.

Dan @ Code Town

WM, it's called Tacking against the wind...an old sailing tactic.

WebShaman | Asylum D & D | D & D Min Page

It seems to me that tacking aginst the wind only works when the craft has a keel.



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-- not necessarily stoned... just beautiful.

What about a catamaran? I think it is without very big keels.


And quite frankly, the keel is used because water provides nice resistance. The vacumn of space doesn't seem to provide much of that. A keel normally prevents cantering.

There are other ways to stabilize things.

(Edited by WebShaman on 05-06-2005 21:37)

Add to that that in vacum there's no point of reference/gravity to stabilize to.

Damn, my kingdom for a magic stick to witness the space crafts we'll have in just 5 centuries.

^ AMEN!!!!!!

Eh, you guys do understand that I was joking with the mirror thing...
/Dan

{cell 260} {Blog}
-{ ?There are two major products that come out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence. - Jeremy S. Anderson" }-

Ummm... very yes, becuase the mirror wouldn't work... in order to travel towards the sun like that the pressure on the inside of the sail would need to be greater than the pressure ouside it. With that mirror there's no way you could do it. in fact I don't see how you could tack towards the sun either. Part of tacking involves the positioning of the tiller, and in space you don't have a nice resistant body of water to steer your tiller through.


Justice 4 Pat Richard

well, what about a mirror like this ( i don't know how to draw that well yet on the computer)

ug, i don't know how to put the picture on, can someone tell me how? i use windows.

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WebShaman said:

^ AMEN!!!!!!

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"once i have fought, and now i am dead, but do not worry, for you shall also be deceased"

You have to have a webhost to upload the image to first, then use [img] tags to display it.


Justice 4 Pat Richard