So a solar powered spacecraft has been tested. A big sail catching photons to slowly accelerate s vehicle to a high speed. Sooo when you get where you are going how do you stop? Put your foot out? How do you steer? Annd how do you see where you are going with that big sail in your windshield?

This message has been edited. Last edited by: DorianGreyed,

i belive the idea behind the sail is so that we can use it to power a craft for LONG distances such as from here to mars and beyond our solar system. it would be used mostly as a transport and probalby have a shuttle to take the crew to the planet.

to stop i am sure that they could put the sail down, and use rocket power to slow down.
you would steer using rockets too. or jets of air.

the photons would not give it great acceleration, but would slowly accelerate it to higher and higher speeds, allowing the crew to save fuel for once they get to where they are going.

another ship like this (with slow acceleration but high speeds) already exists, it uses ion propulsion.

check out this web site:
http://www.howstuffworks.com/solar-sail.htm

hope this helps
-chris

Generally it's meant for interstellar missions; the destination star slows the craft. To steer, you use attitude jets to turn the craft. The solar wind will push it in a new direction depending on the craft's new orientation.

By the way, protons are the main source of thrust for a solar sail.

I suppose you could tack. Then go into orbit. Then use thrusters to slow your descent. You could even store some of the energy derived from the stellar wind to power the thrusters. And when you are through with the sails, you could always jettison them. Steering would be by stellar navigation. But many years in space would play havoc with your sails, because at those speeds, the least particle would rip through the flimsy molecule-thick metal like a bullet. Maintenance would be a major problem.

Thanks. That is what I thought for the answers. It just seems so primitive. I'm imagining some advanced species rofl seeing this thing come into view on their scanners. I think we will come up with a more workable concept before anyone out there catchs (solar) wind of this.

gatman: I understand the concept to be for long-haul interstellar travel. The acceleration is of course dependent on the size of the sail and mass of the vehicle.

I'm not specifically familiar with what's been tested (do you have a link?). Perhaps they were only demonstrating the reality of the physical concept. Nobody expects anything practical now. But imagine if future technology could make sails hundreds -- or millions -- of square miles in area!

What's intriguing is its economy: No fuel, just payload with a sail. As Mack Tuesday pointed out, you would use local starlight to slow the craft at its destination.

If you had to use rockets to slow down, as Bibc14 suggested, it would take just as much fuel as a rocket getting up to speed in the first place, defeating the purpose of the sail.

babthrower: I don't think you could tack. I'm not a sailor but as I understand sailboats, tacking upwind requires a keel pushing sideways against water as well as aerodynamic lift pulling sideways to the wind. There would be no analagous forces with solar sails.

Interesting topic

Yeah, come to think of it, I think you're right.

This just in...

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Cosmos 1 Passes Test Milestone:
Solar Sail Blade Is Deployed in Vacuum Chamber

Our Solar sail spacecraft, Cosmos 1, passed a major milestone this week with the successful deployment of a solar sail blade in flight configuration in a vacuum chamber test at NPO Lavochkin in Khimki, Russia.

The 15-meter solar sail blade deployed to its full
length in the 12 meter-vacuum. The deployment tested a redesigned blade packing scheme, which folded - rather than rolled - the blade and its inflatable tube frame.

"Seeing that four-story-long blade deploy in vacuum was a thrill," said Louis Friedman, our Executive Director and the Cosmos 1 Project Director. "Still ahead of us is the extraordinary adventure and drama of unfurling the sail in the zero gravity conditions of orbit."

Read the complete story at:
http://planetary.org/html/news/bladedeploy.html

...dated July 9, 2002.

Kinda slightly off the subject, but still related to "light pressure":

There's an asteroid that may strike Earth 800+ years from now. One way to prevent this would be to dust the asteroid with either black powder (coal dust, etc.) or white powder (chalk, etc.) The effects of the pressure of light would increase if you did this, to ever so slowly alter the asteroid's orbit.

Thank you Professor, that is the story I heard. But are you sure that Bab's idea of tacking won't work? I mean just watch people in their cars when they make turns. The head tilt or body lean sure seems to help a lot of drivers. I always wonder how many of them are making funny-cute-strange noises at the same time !! Is that considered multitasking?