Put an artificial sun in orbit?

[Toadman]

Desmocrat's space thread is great and got me thinking:
Is it theoretically possible and do we have the technology to place a highly-polished mirror in geosynchronous orbit and reflect sunlight onto the earth's surface to provide daylight for, oh lets say, sporting events?
Although it would not radiate heat like the sun, could it reflect enough light to penetrate the atmosphere on a clear day and actually illuminate a concentrated area on the earth? What size of mirror/satellite would it have to be and could it be adjusted to sustain the illumination until earth's shadow envelops it. Or would the illumination be too brief to warrant the expense because of the earth's rotation?

[Wiruz]

moving it would use some sort of fuel, which can't just be generated in space, so it would need to be refueled every once in a while - a very expensive operation if you ask me - but the idea has been discussed by several scientist.

It would be cheaper just using electricity and stadard lighting.

~Wiruz

[BFlurie]

The Russians have been studying that for years -- a couple months of very little sunlight is a big motive. Astronomers would rightfully have a fit, tho. It could be placed in geo-orbit, then slowly rotated to keep the correct reflection angle toward a specific site, or even targeted on different locations. Or (I'm no astronomer), I think there's an L2 or L3 point where an object doesn't orbit the earth -- simply follows it, which would maximize the mirror efficiency. There'd be no fuel usage once in orbit since solar panels could power the required rotation w/gyros.


[This message has been edited by BFlurie (edited 01-05-2001).]

[daveleau]

Yes it could be solar powered and the engines could run off those and solar power battery packs. (?)

[Mykex]

I don't think electrical propulsion is technologically workable yet. In a geo synchronous orbit you could adjust the angle of deflection and refraction to light selected areas on selected intervals. These I don't think could be scheduled beyond availability of the selected orbital pattern.

Or I watch too much Scifi channel and I'm clueless.

[BFlurie]

Well, a giant magnifying glass could be orbited & then aimed at anthills to see those buggers burn.

[Wiruz]

Warthog>
That would not be an option - if you spread out the suns rays, you also spread the energy and thus the power of the light would be smaller.

Electrical propulsion won't be an option for many years - nasa are testing the technology, but it takes a while for technology to go from testing to actual use - electrical propulsion is based on plasma - heating up a metallic rod to the point where plasma is generated around it, and shot backwards.

****... im a nerd

[scotter]

electrical propulsion is workable and has been in use for some time now to move satilites around

[Toadman]

So given today's technology and preciseness of telescopic mirrors, how large an area on the earth could be illuminated to near- daylight conditions by focusing the sun's visible rays, like Bflurie's magnifying glass analogy? 100m? 1km? Bigger? Is it even possible?

ow ow..my head hurts now!

[This message has been edited by Toadman (edited 01-04-2001).]

[Wiruz]

Scotter - i did not know that....

The area that must be illuminated = The size of the mirror - given that the rays from the mirror don't spread....

[brandon184]

Why would the size of the mirror matter? If the mirror was split into different parts and placed perfectly, they could probably light up huge areas.

As for fuel, what powers these little probes that go into deep space for years and years? I forget, but isn't it something nuclear?

As for getting it up there - build it in space!

- Brandon

[otheos]

As Bflurie said, the russians were working on a project to use reflected solar light to illuminate parts of siberia. However the astronomical society was very worried due to the scattered light in the upper parts of the atmosphere that such a massive light pensil would cause and after loads of pressure the russians (ok the truth is money was scarse too) abandoned the project.

As for the posision of the mirror, it would have to be geostationary as the Laplace points are only good for constant distance probes.

There was a link in poor english about it, I'll try to find it and post it (but it's been at least 3 years now...)

[BFlurie]

I think the Ruskies had in mind to light up Moscow during the winter months. It wouldn't be like daylight -- more like 2X-3X a full moon.

[Toadman]

Knowing how bright it can be on full-moon clear nights with sunlight reflecting off its irregular surface, I suppose it could get quite intense from an orbiting reflector/refractor satellite. It might probably need to be diffused like an automotive headlight. Still, it's a fascinating theory, even with the possible ramifications of disrupting organic lifecyles .

"Cue the Sun" - The Truman Show

[This message has been edited by Toadman (edited 01-04-2001).]

[BBA]

Think of it...if it is big enough, it would really be man made global warming, lol

brandon184...Nuclear power for probes is very simple. They use a radioactive element, cesium ( don't quote me on the exact material used ), that simply generates heat from normal radioactive decay. This heat is converted to electrical power by the thermocouples. Thermocouples ( yes, peltier elements ) produce a voltage based on the temperature it is exposed to. Conversely, it will produce a temperature based on the electrical voltage it is exposed to ( IE: Peltier coolers for your CPU )

The fuel cell the long reach probes use is purely for operation of it's electronics and control systems...not for propulsion. This is due to the fact the probe will not always have sufficient solar power to operate. Propulsion was set by normal rocket propellant on the way there and solar orbits control their trajectory. They do have small gas jets for minor corrections.