solar sail project.

Hello friends,

Uptil we are using rocket ( fuel) powered spacecraft for space travel.
For traveling in space we are using propellant but we can also use solar energy from sun
To propel our spacecraft.i.e. I am talking about the Nasa’s solar sails project.

Hundreds of space missions have been launched since the last lunar mission, including several deep space probes that have been sent to the edges of our solar system. However, our journeys to space have been limited by the power of chemical rocket engines and the amount of rocket fuel that a spacecraft can carry. Today, the weight of a space shuttle at launch is approximately 95 percent fuel. solar sails will use the sun's power to send us into deep space. Solar sails use the sun's energy to propel spacecraft across the cosmos.

There are three components to a solar sail-powered spacecraft:
• Continuous force exerted by sunlight
• A large, ultrathin mirror
• A separate launch vehicle

With just sunlight as power, a solar sail would never be launched directly from the ground. A second spacecraft is needed to launch the solar sail, which would then be deployed in space. Another possible way to launch a solar sail would be with microwave or laser beams provided by a satellite or other spacecraft. These energy beams could be directed at the sail to launch it into space and provide a secondary power source during its journey. Once launched, the sails are deployed using an inflatable boom system that is triggered by a built-in deployment mechanism.

As it continues to be pushed by sunlight, the solar sail-propelled vehicle will build up speeds that rocket powered vehicles would never be able to achieve. Such a vehicle would eventually travel at about 56 mi/sec (90 km/sec), which would be more than 200,000 mph (324,000 kph). That speed is about 10 times faster than the space shuttle's orbital speed of 5 mi/sec (8 km/sec).
If interstellar probe was launched powered by solar sails, it would take only eight years for it to catch the Voyager 1 spacecraft (the most distant spacecraft from Earth), which has been traveling for more than 20 years. By adding a laser or magnetic beam transmitter, it could push speeds to 18,600 mi/sec (30,000 km/sec), which is one-tenth the speed of light. At those speeds, interstellar travel would be an almost certainty.

Ashish said :

"You might be wondering what happens when the spacecraft finds itself far from sunlight. An onboard laser could take over providing the necessary propulsion to the sails.

Theoretically, the laser beam and spacecraft is a closed system, the laser-beam pushes the craft-attached sail with a force F, the sail will push the laser source in same magnitude but opposite direction. Thats why we can't propel a sailboat with a on-board fan.

Would you please explain the idea of onboard things? (for me who didn't understood at least)

Madman said :
"Theoretically, the laser beam and spacecraft is a closed system, the laser-beam pushes the craft-attached sail with a force F, the sail will push the laser source in same magnitude but opposite direction. Thats why we can't propel a sailboat with a on-board fan."

Ashish replied :

"it doesn't matter whether the light is impact on solar sail force fully or not..
here the simple concept is the reflective nature of the sails is key. As photons (light particles) bounce off the reflective material, they gently push the sail along by transferring momentum to the sail. Because there are so many photons from sunlight, and because they are constantly hitting the sail, there is a constant pressure (force per unit area) exerted on the sail that produces a constant acceleration of the spacecraft.

You say "there is a constant pressure (force per unit area) exerted on the sail that................"

So there is a force, thermodynamically we can so there is a force, and there is no doubt there is a force, let's denote it with F.

Now the laser beam source is connected with the spacecraft. And if we take the source applies a force on the sail, which is F, this won't hurt the idea. This is action.

Simply there will be a reaction (Very Basic Rule ;D). That means spacecraft will exhort a force on the beam, as well as on the source, with magnitude F and opposite direction, making the whole thing a closed system.

Not as similar as sunlight as you said....

When the source was sun, the spacecraft used to push sun as well. but so little was suns accelaration (because of enormous mass), it was negligible, which means, sun-spacecraft is not a closed system.

I think that is why we (I at least) can't drive a car by pushing it from inside. Similarly a fan, generating air-beam, installed in a sailboat, can't drive (or propel, whatever)it, even though the air-beam is reflecting from the sail.

Forgive me for my silly brain and the Careless I had been earlier... But I would be very grateful if you please kindly explain how on board things drive the stuff.

Ashish Said

"hi madman,
taking the example of car
suppose ,if u throw the big stone on car from outside then car will move forward because potential energy of stone is converted into kinetic energy of car.
similarly consider the cabin of car is large if u throw the same stone with same force by sitting inside the car on desktop of car then also the car will move forward because the potential energy of stone is converted into kinetic energy of car."

Does this follow the rule of conservation of momentum etc basic rules? Probably no...And try to do that practically. Please don't mind, that has not been possible since last 20,000 years, from when human being have invented wheel. I don't say it's impossible, it hadn't been possible (due to basic rules), but, thing is, if we can discover other rules, it might have been possible..................

The website supplied by Ashish says :

"If the acceleration diminishes due to an increasing distance from the Sun, some scientists have proposed pointing powerful laser beams at the spacecraft to propel it forward. "

I didn't find any mention of ON-BOARD laser there. (Used ^F in Mozilla Firefox :-)). It says a laser beam can take over, as proposed, but it's NOT ON-BOARD .... That solves the problem ............ :D:D

Thanks a million for the link.............. I knew lasers could take over, i was just wondering about "on-board" problem........ Now I confirmed, my question was right...