heptane. n. 1. (Elements & Compounds) an alkane existing in nine isomeric forms, esp the isomer with a straight chain of carbon atoms (n-heptane), which is found in petroleum and used as an anaesthetic. Formula: C7H16. [C19: from hepta- + -ane, so called because it has seven carbon atoms].
technically it's not any of those three... After the Apollo program in the late 1960's ended, the president of the United States, Richard Nixon declared in 1973 that the USA would build the Space Shuttle to continue space exploration in low earth orbit.
Space shuttle program ends: Were Americans sad to see it go? The last space shuttle mission ended Thursday when Atlantis landed, and Americans aren't confident that Obama administration knows where to take human spaceflight next.  July 21, 2011. Space shuttle Atlantis lands at the Kennedy Space Center at Cape Canaveral, Fla., Thursday, marking the end of NASA's 30 year space-shuttle program. Americans opinions about the future of US human spaceflight program appear to be as ambivalent and conflicting as the opinions that now vex the space community itself.