Solar Sails

carpediem55 writes "Reuters is reporting that The Planetary Society (founded by Carl Sagan) is bringing science fiction to life, with a Solar Sail powered by light." But get how they plan to launch it: on a Russian submarine ICBM. The sponsors have a site with more information.

Comments

I can see the exchange now...

[Chris Burke]

Norad: Umm... We just detected a ICBM launch from the Russian submarine Smirnof.

Kremlin: Not a problem, comrad! Is just launch of solar-sail you may have been reading about on slashdot.

Norad: Okay... Umm... Our projected trajectory puts it landing in Washington, DC.

Kremlin: Is normal! It will separate at high altitude and booster will fire sail into space. Missile will fall harmlessly into Atlantic.

Norad: Okay... Umm... The ICBM appears to have landed in the capitol, exploded, and wiped out our entire government...

Kremlin: Is this a problem, comrad?

Norad: No, not really. Just commenting.

Wrong one!

[Wog]

But get how they plan to launch it: on a Russian submarine ICBM.

(Jump forward 4 years, under the sea, in a Russian sub.)

Weapons Officer: Missile number five has been launched. That's one small step for man, one giant-

Captain: Gustov! You mean missile number nine, right?

Weapons Officer: Shazbot!

Re:This is part of our destiny.

[JCMay]

I read that link you posted, and I am unimpressed. All they did was prove that the phase velocity of a propagating EM field can indeed go faster than c. The article even mentions the sweeping beam of a lighthouse. If we assume that the beam is rotating with an angular velocity P, then at some point away from the lighthouse r, the linear velocity of the beam v will be equal to c: v = Pr. That's easily determined: r = c/P. Beyond this radius the linear velocity of the beam will be greater than c even though the beam propigation in the r direction will be only equal to c.

Of course, if you wanted to send a signal faster than c, the group velocity of that EM field would have to exceed c, which it doesn't.

Since the speed of light, c, is determined by whatever the substance is that the EM field is propagating through by the equation

c = 1/sqrt(u*e)

Where u is the permeability of the substance and e is the permittivity. Each of these values is made up of two parts, the intrinsic value and the relative value. The intrinsic permeability of free space (u0) is 1.257e-6 H/m. The intrinsic permittivity of free space (e0) is 8.854e-12 F/m. In a vacuum the relative permeability and the relative permittivity are both 1. This gives a free-space value for c of 2.998e8 meters/sec.

In a non-vacuuum, either or both of the relative terms will be greater than 1, and the value of c in those mediums will be less than the free-space value.

The key to propagating signals faster than 3e8 m/sec is to find a material with a dielectric constant (relative permittivity) between zero and 1. These materials don't exist, however.

The Father of the Solar Sail....

[GeneralEmergency]

I was fortunate enough to be in Russia several years ago (as part of a NASA contract) and got to meet and work with Professor Vladimir Syromyatnikov, the father of the Solar Sail, who is one of the most gracious and intelligent men I have ever met. He is truly a brilliant mechanical engineer. His genderless docking collar design is a work of poetry in steel.

The good professor was kind enough to invite me up to his apartment one day to talk over lunch and meet his wife and family.

I often think about that afternoon and in particular, one corner of his living room where his television set was placed. There, atop the tv was a VCR and yup, you guessed it, the clock was blinking "12:00". To this day, whenever I need to assess my own failings, I just remind myself "Even Rocket Scientists can't do everything".

You can email the professor at:
vladimir.syromyatnikov@rsce.nasa.ru

"A microprocessor... is a terrible thing to waste." --

Space.com

[Eoli]

Space.com has more on the subject here.

There's a better way..

[Blind RMS Groupie]

This is certainly interesting, especially in that it's being done by a private firm, but I find the idea of Mini-Magnetospheric Plasma Propulsion (M2P2) much more fascinating. The idea is that you replicate a miniature version of the Earth's magnetosphere around a spacecraft and let the plasma push against that instead. The beauty of it is that thrust remains relatively constant because as the craft moves farther away from the sun the reduced plasma pressure results in a correspondingly larger artifical magnetosphere. Also the thrust can be varied electronically instead of mechanically and there's no moving parts.

--

Re:Small question...

[vidarh]

Launching from a sub does make sense for several reasons:

First of all, the Russians do their land based launches from Baikonur, which is relatively far north. Normally, you'd prefer to do launches close to equator to get the maximal benefit of earth rotation. The Russians incur a lot of extra costs because of the position of Baikonur. (and this is also one of the reasons for the orbit MIR is in - they need to get it far enough north to be able to reach it cheaply from Baikonur). Launching from sea means they'll be able to launch from international waters and be independent of having their own land based launch areas near equator.

Second, there's strict international regulations on such launches, to prevent interference with aircraft. Which you should be happy about the next time you're flying anywhere... :) Launching from sea simplifies things, because most traffic is clustered around or between big cities, and the further out at sea you go, the less flights will pass through the area. So it reduces the administrational issues of ensuring no passenger flights or other aircrafts pass right overhead during the launch.

Environmental effects and other hazards are always an issue during rocket launches. The rocket can misfire, or explode. Parts may be hurtled through the area in the case of an accident. Dangerous materials or toxic gases may be released as a result of fire etc. Tons of things can go wrong. While it won't be good at sea either, at least you face less immediate threats to human life.

You also lessen the environmental impact of indigneous animals etc. (which has been a major concern with ESAs Ariane launch site in Central America).