welcome back. right now, nasa astronauts are stepped out of the space station and out to spacewalk. their objective is to install a solar panel on the space station and doing it as a asteroid the size of a brooklyn bridge is set to pass by. it is the size of the next five asteroids passing planet. and joining us is a professor of astrophysics at the university of rochester, and the author of the book the little aliens. so, i think that we should start with the space station that has to be constantly upgraded, and how risky are these spacewalks? well, people have been take it for granted that we have been