The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

next century. To cut costs further, NASA opted for a
more traditional, partly expendable system to carry
the Orbiter into space, involving drop-away boosters
and an expendable main engine fuel tank.
Rockwell began work on Orbiter Enterprise, officially
known as Orbiter Vehicle-101 (OV-101), in June
1974. This was first rolled out of its hangar at Palmdale,
California, on September 17, 1976, and subse-
Space Shuttle Atlantis heads
skyward from Launch Pad 39A
on March 24, 1992, carrying a
crew of seven and the Atmospheric
Laboratory for Applications
and Science-1. NASA
quently used for flight testing at the Dryden Flight
Research Center. Meanwhile Rockwell continued to
develop Orbiters Columbia (OV-102), Discovery (OV-
103), and Atlantis (OV-104). Although Enterprise was
originally intended to be refitted as an operational
Shuttle, NASA opted instead to upgrade Challenger
(OV-099) from its status as a high-fidelity structural
test article. Upon the loss of Challenger in January
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