Thanks for the replies! My probes are Stayputniks with a pair of solar panels attached. They each have the smallest fuel tank with the smallest thrusters on them with all science equipment affixed to the fuel tanks. It also has the long range antenna on the top, with 4 short range antennas on the back to kind of simulate a Sputnik feel. To get them into orbit around Kerbin it took, I think, three tries. And to get around Mun it took two, although it's not a circular orbit so I'm going to try again later today. I'm having some trouble when I separate form my launch rockets, I'm using the nuclear engine and when I detach it sends my ship spinning end over end and I have to manually recover when I'm trying to expand my orbit. Any tips on how to have more control when I detach in orbit? Do I need more thrusters or is it a weight balance issue? Thanks so much!