1 October 2003
b. Other uses of laser fluorosensors are to detect uranium oxide present in facilities,
abandoned mines, and spill areas that require remediation. See Special Technologies
3-11 Airborne Gamma.
a. An AC-500S Aero Commander aircraft is used by the National Operational Hy-
drologic Remote Sensing Center (NOHRSC) to conduct aerial snow survey operations in
the snow-affected regions of the United States and Canada. During the snow season
(JanuaryApril), snow water equivalent measurements are gathered over a number of the
1600+ pre-surveyed flight lines using a gamma radiation detection system mounted in the
cabin of the aircraft. During survey flights, this system is flown at 500 ft (152 m) above
the ground at ground speeds ranging between 100 and 120 knots (~51 to 62 m/s).
Gamma radiation emitted from trace elements of potassium, uranium, and thorium radio-
isotopes in the upper 20 cm of soil is attenuated by soil moisture and water mass in the
snow cover. Through careful analysis, differences between airborne radiation measure-
ments made over bare ground are compared to those of snow-covered ground. The radia-
tion differences are corrected for air mass attenuation and extraneous gamma contamina-
tion from cosmic sources. Air mass is corrected using output from precision temperature,
radar altimeter, and pressure sensors mounted on and within the aircraft. Output from the
snow survey system results in a mean areal snow water equivalent value within 1 cm.
Information collected during snow survey missions, along with other environmental data,
is used by the National Weather Service (NWS), and other agencies, to forecast river lev-
els and potential flooding events attributable to snowmelt water runoff
b. Other companies use airborne gamma to detect the presence of above normal
gamma ray count, indicative of uranium, potassium, and thorium elements in the Earth's
tory at Bechtel, Nevada). The USGS conducted an extensive survey over the state of
Alaska as part of the National Uranium Resource Evaluation (NURE) program that ran
3-12 Satellite Platforms and Sensors.
a. There are currently over two-dozen satellite platforms orbiting the earth collecting
data. Satellites orbit in either a circular geo-synchronous or polar sun-synchronous path.
Each satellite carries one or more electromagnetic sensor(s), for example, Landsat 7 sat-
ellite carries one sensor, the ETM+, while the satellite ENVISAT carries ten sensors and
two microwave antennas. Some sensors are named after the satellite that carries them, for
instance IKONOS the satellite houses IKONOS the sensor. See Appendices D and E for a
list of satellite platforms, systems, and sensors.
b. Sensors are designed to capture particular spectral data. Nearly 100 sensors have
been designed and employed for long-term and short-term use. Appendix D summarizes
details on sensor functionality. New sensors are periodically added to the family of ex-