Aerosol Sensor Delivered To Orbital For Installation On Glory
Spacecraft
The Aerosol Polarimetry Sensor (APS), an advanced scientific
instrument that will be launched on the Glory satellite, has
successfully completed environmental testing and was officially
turned over to NASA on March 11 by the Raytheon Company, Waltham,
MA which built the instrument. APS was delivered on March 9 to the
Orbital Sciences Corporation in Dulles, VA for integration with the
Glory spacecraft.
The milestone comes after four months of testing at a Raytheon
facility in El Segundo, CA during which the APS underwent a series
of vibration, electromagnetic compatibility, calibration, and
thermal vacuum tests.
"APS is on track and ready to go," said Jeff Hein, the APS
instrument manager for Glory at NASA's Goddard Space Flight Center
in Greenbelt, MD. "It was a very robust set of tests, and the
instrument performed well."
With this round of environmental tests complete, engineers and
technicians at Orbital Sciences, the spacecraft and launch vehicle
provider, can now install APS on the spacecraft. After APS is
integrated, the entire spacecraft will undergo additional
system-level environmental tests in preparation for launch.
"The APS performance was excellent at the beginning of the test
program and has been essentially unchanged throughout all of the
testing," said APS instrument scientist Brian Cairns of NASA's
Goddard Institute for Space Studies. "The instrument should provide
extremely precise measurements that will allow us to provide the
highest-quality aerosol observations ever retrieved from
space."
Once in orbit, APS will study tiny airborne aerosol particles to
better understand their influence on climate. The instrument will
view aerosols through polarizing filters that screen out certain
orientations of light waves. The technique will allow scientists to
measure and characterize aerosols that would otherwise be obscured
by background glare from the Earth's surface and from atmospheric
gases.
Aerosols are of great interest to climatologists. Some types,
including black carbon from traffic exhaust, promote warming by
absorbing sunlight. Others, such as sulfates from coal power
plants, exert a cooling effect by reflecting incoming solar
radiation back into space. For some types of aerosols -- including
naturally occurring mineral dust particles -- it isn't clear how
they might affect climate. Overall, aerosols represent one of the
greatest areas of uncertainty in understanding the climate
system.
In addition to APS, Glory will carry a second instrument -- the
Total Irradiance Monitor (TIM) -- that will measure the sun's
energy output. The TIM instrument recently completed calibration at
a first-of-its-kind radiometer facility -- the TSI Radiometer
Facility -- at the Laboratory for Atmospheric and Space Physics at
the University of Colorado in Boulder.