Read the text below to answer the questions 11-15.
NASA Researchers Studying Advanced Nuclear
Rocket Technologies
January 9, 2013
By using an innovative test facility at NASA's Marshall
Space Flight Center in Huntsville, Ala., researchers are able to
use non-nuclear materials to simulate nuclear thermal rocket
fuels – ones capable of propelling bold new exploration missions
to the Red Planet and beyond. The Nuclear Cryogenic
Propulsion Stage team is tackling a three-year project to
demonstrate the viability of nuclear propulsion system
technologies. A nuclear rocket engine uses a nuclear reactor to
heat hydrogen to very high temperatures, which expands
through a nozzle to generate thrust. Nuclear rocket engines
generate higher thrust and are more than twice as efficient as
conventional chemical rocket engines.
The team recently used Marshall's Nuclear Thermal
Rocket Element Environmental Simulator, or NTREES, to
perform realistic, non-nuclear testing of various materials for
nuclear thermal rocket fuel elements. In an actual reactor, the
fuel elements would contain uranium, but no radioactive
materials are used during the NTREES tests. Among the fuel
options are a graphite composite and a "cermet" composite – a
blend of ceramics and metals. Both materials were investigated
in previous NASA and U.S. Department of Energy research
efforts.
Nuclear-powered rocket concepts are not new; the United
States conducted studies and significant ground testing from
1955 to 1973 to determine the viability of nuclear propulsion
systems, but ceased testing when plans for a crewed Mars
mission were deferred.
The NTREES facility is designed to test fuel elements and
materials in hot flowing hydrogen, reaching pressures up to
1,000 pounds per square inch and temperatures of nearly 5,000
degrees Fahrenheit – conditions that simulate space-based
nuclear propulsion systems to provide baseline data critical to
the research team.
"This is vital testing, helping us reduce risks and costs
associated with advanced propulsion technologies and ensuring
excellent performance and results as we progress toward further
system development and testing," said Mike Houts, project
manager for nuclear systems at Marshall.
A first-generation nuclear cryogenic propulsion system
could propel human explorers to Mars more efficiently than
conventional spacecraft, reducing crews' exposure to harmful
space radiation and other effects of long-term space missions. It
could also transport heavy cargo and science payloads. Further
development and use of a first-generation nuclear system could
also provide the foundation for developing extremely advanced
propulsion technologies and systems in the future – ones that
could take human crews even farther into the solar system.
Building on previous, successful research and using the
NTREES facility, NASA can safely and thoroughly test simulated
nuclear fuel elements of various sizes, providing important test
data to support the design of a future Nuclear Cryogenic
Propulsion Stage. A nuclear cryogenic upper stage – its liquidhydrogen
propellant chilled to super-cold temperatures for
launch – would be designed to be safe during all mission phases
and would not be started until the spacecraft had reached a safe
orbit and was ready to begin its journey to a distant destination.
Prior to startup in a safe orbit, the nuclear system would be cold,
with no fission products generated from nuclear operations, and
with radiation below significant levels.
"The information we gain using this test facility will permit
engineers to design rugged, efficient fuel elements and nuclear
propulsion systems," said NASA researcher Bill Emrich, who
manages the NTREES facility at Marshall. "It's our hope that it
will enable us to develop a reliable, cost-effective nuclear rocket
engine in the not-too-distant future."
The Nuclear Cryogenic Propulsion Stage project is part of
the Advanced Exploration Systems program, which is managed
by NASA's Human Exploration and Operations Mission
Directorate and includes participation by the U.S. Department of
Energy. The program, which focuses on crew safety and mission
operations in deep space, seeks to pioneer new approaches for
rapidly developing prototype systems, demonstrating key
capabilities and validating operational concepts for future vehicle
development and human missions beyond Earth orbit.
Marshall researchers are partnering on the project with
NASA's Glenn Research Center in Cleveland, Ohio; NASA's
Johnson Space Center in Houston; Idaho National Laboratory in
Idaho Falls; Los Alamos National Laboratory in Los Alamos,
N.M.; and Oak Ridge National Laboratory in Oak Ridge, Tenn.
The Marshall Center leads development of the Space
Launch System for NASA. The Science & Technology Office at
Marshall strives to apply advanced concepts and capabilities to
the research, development and management of a broad
spectrum of NASA programs, projects and activities that fall at
the very intersection of science and exploration, where every
discovery and achievement furthers scientific knowledge and
understanding, and supports the agency's ambitious mission to
expand humanity's reach across the solar system. The NTREES
test facility is just one of numerous cutting-edge space
propulsion and science research facilities housed in the state-ofthe-art
Propulsion Research & Development Laboratory at
Marshall, contributing to development of the Space Launch
System and a variety of other NASA programs and missions.
Available in: http://www.nasa.gov
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