|
The
Microgravity Emissions Laboratory (MEL) was developed
for the support, simulation and verification of the
International Space Station (ISS) microgravity environment.
The MEL utilizes an inertial measurement system using
acceleration emissions generated by various operating
components of ISS. These emissions, if too large, could
hinder the science performed on ISS, by disturbing the
microgravity environment.
Typical
test components are disk drives, pumps, motors, solenoids,
fans, cameras, etc. These components will produce inertial
forces, which disturb the microgravity on-orbit station
environment. These components, usually housed within
a station rack, must meet acceleration limits imposed
at the rack interface for minimizing the on-board station-operating
environment. NASA GRC has developed this one of a kind
laboratory for testing components and eventually rack
level configurations. The MEL approach is to measure
the component's generated inertial forces. This force
is a product of the full diagonal mass matrix including
the test setup (the center of gravity, mass moment of
inertia, and weight) and the resolved diagonal rigid
body acceleration made up using the 10 apparatus accelerometers.
The mass matrix can be test derived. The moment of inertia
for the test component is measured using the bifilar
torsional pendulum method.
The
MEL is a low frequency (0.15-0.4 Hz) isolator. The lateral
frequencies are established with the pendulum and the
vertical mode is lowered with a zero rate spring mechanism
(ZSRM). The ZSRM reduces the system's vertical frequencies
to approximately 0.3 Hz. The ZSRM suspends the measurement
apparatus with the attached test unit by a long cable.
The system allows the test article to float freely similar
to a zero-g condition above 1 Hz. The measured motion
of the rigid body is characterized through the MEL test
and post processing of the accelerometer data is done
to calculate the rigid body component forces and moments
at the center of gravity/interface of the test unit.
MEL
was developed for the Fluid Combustion Facility through
the Microgravity Sciences Division (MSD). The laboratory
is located in the Structural Dynamics Laboratory (SDL).
Engineering models of the FCF Optics Bench and Air Thermal
Control Unit have been tested in FY 01.
These
test are done on operating equipment; therefore pre-test
planning is a must. All umbilicals, services such as
water, power etc. are provided by the customer unless
alternate arrangements are made. Due to the isolation
required, umbilicals and support service lines need
to be long (5-10 meters). The operations matrix is also
provided by the customer. Any non-standard fixturing
issues will need to be resolved as test planning begins.
Any help needed in formulating these needs can be rapidly
responded to by filling out our on-line
form.
Award
Winning Microgravity Emissions Laboratory
Tom Goodnight accepted the Silver Snoopy Award
from Astronaut Lee Morin on November 1, 2000
for successfully creating the Microgravity Emissions
Testing Laboratory at NASA Glenn Research Center.
|
