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Grumman low-crossrange Phase-B proposal. The company was one of four contenders for NASA's
Phase-B shuttle contract but lost out to North American Rockwell and McDonnell-Douglas in
Alternative Space Shuttle Concepts. In addition to the primary Phase B study contracts,
NASA also awarded three “Alternate Space Shuttle Concept” (ASSC) contracts to Grumman/Boeing,
Chrysler and Lockheed in June 1970. NASA wanted a fallback option in case North American
Rockwell's & McDonnell-Douglas' fully reusable Phase-B shuttle proved to be too expensive.
Grumman and Boeing received the most important of the ASSC contracts to study a stage-and-a-half
shuttle with expendable propellant tanks, and a reusable orbiter+booster using existing Saturn
J-2S engines and solid rocket motors on the booster for additional thrust augmentation. The
contract was initially worth $4 million and was later upgraded into a full Phase-B contract.
Saturn S-IV-B upper stage separates from shuttle booster in this Boeing illustration from late 1970.
NASA had been forced to shut down the Saturn V production lines in 1970 due to severe budget
cutbacks, and the agency had to look at other options for launching future heavy payloads such
as space stations and nuclear orbital transfer vehicles. Boeing and Grumman examined a number
of shuttle booster+expendable upper stage configurations in late 1970, and
McDonnell-Douglas & Martin Marietta later carried out a similar study in early 1971. McDAC
found out that the Shuttle booster + Saturn S-IV-B option would have been capable of carrying
54,431 kilograms into orbit for $23.7 million per flight -- $1,850/kg in 1999 dollars.
The estimated development cost was $82 million while a nuclear upper stage with Saturn S-II
tankage would have cost $106 million plus $24.18 million (=$1760/kg at 1999 rates) per flight.
Its payload capability would have been 59 tonnes. However, the preferred option was a totally new
$320-million expendable upper stage built from shuttle booster and orbiter components capable
of carrying 77,710 kilograms for only $17.51 million per launch (=$970/kg in 1999 dollars).