What would happen if you dropped a 1-kg rock from 1000 miles up unto the surface of a neutron star?

Answer 1

Well, you couldn't, because my calculations tell me that if you get closer than about 5000 km. from a neutron star, the tidal forces, that is the difference between the gravity pull on your feet and your head, would stretch you out and kill you. If you built a strong robotic vehicle that could get to within 1600 km of the surface, the rock would be pulled to powder by tidal forces before it hit the surface. The bits would hit the surface at up to a third of the speed of light, 100 000 km/second, depending on the mass of the neutron star. They'd get so hot on impact that they'd emit X-rays, which, as they climbed against the neutron star's gravity, would lose energy, and you'd see them from a safe distance as soft X-rays, UV and visible light.The amount of energy radiated would be about 10^15 joules; comparable to the Hiroshima bomb. The mass of the neutron star would increase by about half a kilogramme or so. The crust of a neutron star probably consists of iron or diamond, and your rock would end up as one of these. It would be interesting to perform this experiment, from a safe distance, with a robot probe, on a neutron star within a whisker of collapsing into a black hole, to see what gives.

Answer 2

I have no idea how much gravitational pull there would be at that altitude but I'm guessing that you and the rock would hit the surface at about the same time.