The idea that the electromagnetic radiation can exert pressure is an interesting idea that I taught in my physics courses. As an example, the idea of using the pressure from solar radiation to power a spacecraft has been around for a long time, and I used to give this as a homework problem.
It looks like it has finally come to fruition. Japan used one to fly by Venus in 2010 and now NASA has deployed one to orbit the Earth. Plans are underway to use one to fly to Jupiter later in the decade.
What kind of speed can they get with craft like these?
David,
That’s a good question to which I do not know the answer. The solar radiation produces a force that can accelerate the craft but there must be some resistance due to dust etc. that causes it to reach terminal speed.
I’ll have to look into it.
Mano --
I’m also curious about the levels of acceleration as well; would a manned solar sailcraft be practical, or does the mass involved pretty much restrict it to unmanned sizes?
Eric
Shalom Mano,
As a Cub Scout in the mid-’60s I remember a three part fiction series in my monthly copy of Boy’s Life that featured a solar sail race. I was fascinated and have been hooked on Science Fiction, and Science, ever since.
Until I became a wind sailor in the Navy I never quite understood how it could be possible to sail up wind. The concept is easier to understand in the case of solar sailing since the sail can be used to decelerate the craft and allow the Sun’s gravity to do the real work.
B’shalom,
Jeff