Will Use Modified Delta IV Boosters, J-2s Instead Of Shuttle Engines

It all came down to money -- the reason NASA has decided to use clusters of modified Delta IV rocket engines to propel the boosters the agency is designing to rocket the upcoming Crew Exploration Vehicle (CEV) into orbit -- and onto the moon -- instead of relying on less-expensive "throwaway" versions of the space shuttle's main engines.

NASA told Florida Today the agency will save nearly half the $40 million cost per engine for the modified shuttle engine -- itself a simpler version of the $80 million reusable engines currently employed on NASA's three-orbiter fleet -- by using the Delta IV powerplant.

"In the long run, the (Delta IV) will be much less expensive to own and operate," said Marshall Space Flight Center deputy director Dan Dumbacher. "Right away, we will be saving $100 million a flight just on the cost of engines."

The decision to use the Delta IV will require modifications to the Apollo-era, Saturn V-derived booster rocket NASA is relying on to launch cargo and manned crews into orbit, and onto such destinations as the moon and Mars.

For starters, the main booster used on the gigantic Cargo Launch Vehicle (or CLV, which would be sent into orbit in advance of the Crew Exploration Vehicle for a trip to the moon) will need to be widened an additional 5 1/2 feet -- to an awe-inspiring 33 feet in diameter -- in order to accommodate the five Delta IV engines, referred to individually as RS-68s.

The upper stage for both the CLV and CEV boosters was also originally intended to be powered by the shuttle-engine-derived motor... but they will now be powered instead by an upgraded version of Pratt & Whitney Rocketdyne's J-2 booster.

The J-2 has seen extensive duty for NASA... it was originally used on the Saturn V booster that sent Apollo astronauts to the moon.

FMI: www.nasa.gov