U.S. space exploration history on U.S. stamps also the only space station NASA launched alone. The 100-ton space station was in Earth's orbit from 1973 to 1979 and it was visited by crews three times in 1973 and 1974. Circling 50 degrees north and south of the equator at an altitude of , Skylab had an orbital period of 93 minutes. There were a plethora of UV astronomy experiments done during the Skylab lifetime, as well as detailed X-ray studies of the Sun. The station was active until July 11, 1979, when it fell out of orbit. The 10-cent Skylab commemorative stamp first day of release took
Militarisation of space would merge with USSTRATCOM. The UCP directed that Unified Combatant Commands be capped at ten, and with the formation of the new United States Northern Command, one would have to be deactivated in order to maintain that level. Thus the USSPACECOM merger into USSTRATCOM. The Soviet Union was also researching innovative ways of gaining space supremacy. Two of their most notable efforts were the R-36ORB Fractional Orbital Bombardment System (FOBS) and Polyus orbital weapons system. The R-36ORB was a Soviet ICBM in the 1960s that, once launched, would go into a low Earth orbit whereupon it would de-orbit for an