Comments on: Solar power to set sail in space

NASA will launch its first solar sail as early as July 29, potentially changing the way space is explored.

[powersville21]

I think you meant to write "the edge of the Solar System," not the edge of the Milky Way. No Earth spacecraft has ever reached the edge of our galaxy. With conventional propulsion systems, that journey could take hundreds of thousands of years.

[powersville21]

Or millions of years.

[InklingBooks]

Ditto this: "The sails will not harness enough energy to carry passengers into space..."

No one's even contemplating earth to orbit with solar sails. With sunlight coming down, how would you go up? I quit listening to an NPR science show because the writers seem to lack a basic understanding of science. This article has the same problem.

[Phazonmutant]

Addressing the line, "frictionless, the sail could potentially accelerate forever," this is true only up to a certain point. Space is not a vacuum -- there is a very small frictional force from the ambient particles. Consider that the motive force is photons, a massless particle, then you can see that even one atom every few thousand miles (which is unrealistically diffuse) from solar wind, etc, can present some obstacle. Also, as velocity approaches the speed of light, it takes more energy to accelerate. There's a "speed limit" for matter. The solar sail could potentially get extremely close to the speed of light, closer than possible with conventional rockets using today's technology, but it will never reach it.
Addressing the previous poster's comment: The issue isn't how would you go up. The issue is that the sails are incredibly fragile and the force from sunlight is incredibly weak. The sails would be ripped apart by their own weight in earth gravity, and even if they weren't they couldn't oppose the force of gravity anyway.

[the_inventor]

It will be interesting to observe all of the effects and to see what distances are possible, if any, with this device as it is tracked through the solar system.