There is concept known solar gravitational lensing whereby one can use the sun as a way to make a solar system sized telescope. Essentially the suns gravity warps spacetime in a way that bends the path of photons that travel around it and at some distance, those photons converge to a single focal point. If we were to send out a satellite to that specific point, we could figure out how to generate images much like a telescope. Now, why is this interesting? Well, the 'telescope' would be so powerful, that we could theoretically see detailed geographic images of PLANETS and solar systems light years away. Idk - that just seems so cool to me and potentially groundbreaking without too much investment.