WASHINGTON — NASA’s Project Constellation
program has been overhauled to include a slightly smaller Crew Exploration Vehicle
(CEV) and a new human-rated booster with an Apollo-era upper stage engine.
Project
Constellation is the name NASA has given for the effort
to develop hardware necessary to replace the space shuttle and return astronauts
to the Moon late next decade.
NASA still
intends to make use of the solid-rocket booster technology
that has helped lift the space shuttle off the pad for a quarter century. But
the agency recently approved CEV launcher plans calling for development of a
new five-segment solid-rocket booster instead of the four-segment motor
currently in production.
NASA also
has dropped plans to power the so-called Crew Launch Vehicle’s upper
stage with a Space Shuttle Main Engine modified to start in flight, opting
instead to go with an updated version of the J-2 engine that was used on
NASA’s Saturn 5
rocket.
Project
Constellation Manager Jeffrey Hanley briefed engineers at Marshall Space Flight
Center in Huntsville, Ala., on these and other changes Wednesday, according to
individuals who spoke on the condition of anonymity because the changes had not
yet been officially announced.
These
changes follow NASA’s decision, announced just last week, to drop the
requirement for a liquid oxygen/methane engine on the CEV
service module and lunar lander, leaving it up to the two competing CEV
contractor teams — led by Lockheed Martin and Northrop Grumman — to
propose whatever propulsion system they deem best.
Other newly
approved changes to the CEV, according to sources familiar with the details,
include reducing the diameter of the vehicle from 18 feet (5.5 meters) to 16.4
feet (5 meters) for additional weight savings and using existing Russian
docking hardware for missions to the International Space Station (ISS).
Previous plans called for using a U.S.-developed system.
These
sources said NASA’s overhauled space transportation plan probably will
not save money in the near term, but should prove cheaper in the long run
because both the J-2 engine and five-segment solid-rocket booster are needed
for the heavy-lift cargo vehicle NASA is developing for the lunar sorties it
still hopes to begin as soon as 2018. By going with the J-2/five-segment
booster combination for the initial CEV flights, NASA can skip development of
an air-lit Space Shuttle Main Engine and put its resources toward producing an
expendable version of that engine, which NASA still plans to use for the
heavy-lift rocket’s main
stage.
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