I went to an interesting talk today. The guy was the chair of the newly founded space-something department in USC and essentially talked about the solar wind.
So the sun is shooting particles (protons and alpha particles) in outer space at speeds 750km/sec . This solar wind extends beyond the solar system out to the interstellar matter. However this interstellar matter also exerts a pressure, and at some point the sun's pressure (the wind) and the interstellar matter pressure cancel out. This is the heliopause. However we don't know how the heliopause looks like and what's going on there.
So this guy has proposed two options for measuring that thing. The first one is to measure the ENAs (Energetic Neutral Atoms) that reach earth. What happens here is that the solar wind hits the intestellar matter (At the heliopause) and these particles are reflected back to earth and we can detect them. One week ago their $134M proposal got approved and the spacecraft measuring the ENAs will be launched in 3 years.
The second option is to measure here in earth the reflected UV radiation that is emanating from the sun and it is reflected by the intestellar matter. This offers better accuracy but more sophisticated equipment is required, so this is a plan for 10-15 years ahead in the future.
He also mentioned the the solar sail is coming close to construction; this is a huge 300m ultra-light sheet (spacecraft) that is accelerated by the solar wind and can travel within 20 years outside the solar system. One of my greatest fears is that I will die so young that I will not be able to witness all the exciting discoveries that are yet to come. So I am trying now to suck as a sponge as much as I can.
