Conference 7.286::space

805.0. "NASA Underwater Tests to Simulate Space Antenna Assembly" by PRAGMA::GRIFFIN (Dave Griffin) Fri Jun 12 1992 13:58

Drucella Andersen
Headquarters, Washington, D.C.            June 9, 1992


H. Keith Henry
Langley Research Center, Hampton, Va.


Jim Sahli
Marshall Space Flight Center, Huntsville, Ala.



RELEASE:  92-84

        NASA engineers are preparing to do the first assembly of
a large-scale, parabolic (double-curve) antenna in a huge water
tank whose buoyancy lets researchers simulate working in the
microgravity environment of space.

        Some future space antennas will be too big to fit inside
a space vehicle, so they will have to be assembled in Earth orbit
from smaller panels attached to a supporting framework.

        This month's tests in the Neutral Buoyancy Simulator at
NASA's Marshall Space Flight Center, Huntsville, Ala., will help
establish assembly times for such antennas, evaluate work
procedures and task coordination and check the compatibility of
the hardware itself.

        The 50-foot dish to be used in the underwater study
mimics the primary reflector of a new type of Earth- observation
instrument.  The dish surface is divided into 37 six-sided
segments that will be mounted on a 315-piece support structure.

        The pieces fit together to make a honeycomb-like surface
pattern.  On an orbiting satellite, the segments would form a
precise reflector that could pick up electromagnetic energy
radiated from Earth and distribute it to various sensors.  The
larger the dish surface, the more accurate the measurements
become.  NASA's Langley Research Center, Hampton,Va., leads the
effort.

        The underwater tests will include construction of the
reflector support structure, attachment of seven reflector panels
each about 7 feet in diameter and the removal and reconnection of
a panel to simulate repair activities.

        Space-suited engineers from Langley will play the role of
astronauts working in Earth orbit.  They will erect the truss
structure from individual stick-like members by manually joining
them with Langley-designed and developed quick-connect joints
similar to hardware tested on the recent STS-49 Space Shuttle
mission.

        During the simulation, one "astronaut" will remove the
truss members and joints from canisters, while the other
assembles the pieces into the truss.  After part of the truss has
been built, the test subjects will reorient their foot restraints
and attach a series of reflector segments.

        The mockup will be assembled on a fixture anchored to the
bottom of the water tank.  The fixture will support and move the
truss during its construction and position the engineers as they
move the footpads.

        Researchers estimate that it will take about 3 hours to
build the reflector mockup.  The experience gained during this
test will lead to refinements in precision reflector hardware
being developed at Langley Research Center. NASA also is working
on ways to create large space antennas using deployable
structures, as well as by robotic and robot-assisted assembly.

        Scientists will use precision reflectors to study the
structure and origin of the universe and to improve understanding
of environmental and climatic changes occurring on Earth.