October 2004
A Summer Vacation Tracking
Down UFOs
By Diane K. Fisher
Erin Schumacher's summer job for NASA was to look for UFOs. Erin is a
16-year-old high school student from Redondo Beach, California, attending the
California Academy of Mathematics and Science in Carson. She was one of ten
students selected to work at NASA's Jet Propulsion Laboratory (JPL) in Pasadena
as part of the Summer High School Apprenticeship Research Program, or SHARP.
But is studying UFOs a useful kind of NASA research? Well, it is when they are
"unidentified flashing objects" that appear in certain images of Earth from
space. Erin worked with scientists on the Multi-angle Imaging SpectroRadiometer
(MISR) project to track down these mysterious features. MISR is one of five
instruments onboard the Earth-orbiting Terra satellite. MISR's nine separate
cameras all point downward at different angles, each camera in turn taking a
picture of the same piece of Earth as the satellite passes overhead. Viewing the
same scene through the atmosphere at different angles gives far more information
about the aerosols, pollution, and water vapor in the air than a single view
would give. Ground features may also look slightly or dramatically different
from one viewing angle to another.
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Two cameras on MISR made these images of
the same part of the Mojave Desert. The camera pointed at an angle of 26 forward saw the flashes from two solar electric power generating stations. These objects are nearly invisible at the other angle. |
Erin's job was to carefully examine the
pictures looking for any flashes of light that might be visible from just one of
the nine angles. Such flashes are caused by sunlight bouncing off very
reflective surfaces and can be seen if a camera is pointed at just the right
angle to catch them. Because the satellite data contain precise locations for
each pixel in the images, Erin could figure out exactly where a flashing object
on the ground should be. Her job was then to figure out exactly what it was that
made the flash-in particular, to see if she could distinguish man-made objects
from natural ones.
When Erin began working at JPL, scientists on the MISR project had already
identified two large flashes out in the middle of the Mojave Desert in Southern
California. These turned out to be from solar power generating stations. Soon,
Erin began finding flashes all over the place. She learned how to apply her math
knowledge to figuring out how the objects would have to be oriented in order to
be seen by a particular MISR camera. One time, she and a team of MISR scientists
and students went on a field trip to the exact locations of some flashes, where
they found greenhouses, large warehouses with corrugated metal roofs, a
glass-enclosed shopping mall, and a solar-paneled barn. For some flashes, they
could find nothing at all. Those remain "UFOs" to this day!
Learn more about SHARP at www.nasasharp.com
and Earth science applications of MISR at
http://www-misr.jpl.nasa.gov. Kids can do an online MISR crossword at
http://spaceplace.nasa.gov/en/kids/misr_xword/misr_xword1.shtml.
This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.