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.
The first blow came in 2004, when then-President George W. Bush announced the end of the space shuttle program. His plan was to replace it with a return-to-the-moon program run out of Houston. Then in 2010, President Barack Obama canceled that over-budget Houston-centric shuttle replacement program. He proposed going to an asteroid in a plan that at the moment is less detailed, especially when it comes to Houston's role.