A
NASA sounding rocket mission,
launching Wednesday, will study radio waves that escape through the
Earth’s ionosphere impacting the environment surrounding Global
Positioning System (GPS) and geosynchronous satellites, such as those
for weather monitoring and communications.
Launching from NASA’s Wallops Flight
Facility, a Terrier-Improved Malemute suborbital sounding rocket will
carry the Vlf trans-Ionospheric Propagation Experiment Rocket,
or VIPER. The mission is scheduled for at 9:15 p.m. EDT. The launch
may be visible in the mid-Atlantic region.
VIPER is studying very low frequency
radio, or VLF, waves that are produced by both natural (e.g.
lightning) and artificial means. During the day these waves are
trapped or absorbed by the Earth’s ionosphere. At night, however,
some of the waves escape through the ionosphere and accelerate
electrons in the Van Allen Radiation Belt.
“At night, the lower layers of the
ionosphere are much less dense, and more of the VLF can leak through,
propagate along the Earth's magnetic field lines,” said John
Bonnell, the project’s principal investigator from the University
of California, Berkeley.
“Those belts of intense energetic
electron fluxes cover a range of distances from the Earth, from as
close as 14,300 miles altitude out to 23,500 miles altitude. GPS
satellites and geosynchronous satellites orbit the Earth at these
altitudes. So, satellites in those orbits are often engulfed by the
Van Allen Radiation Belts and have to tolerate the effects those
energetic particles have on electronics and materials,” said
Bonnell.
In addition to the in-situ measurements
made by VIPER as it flies through the area of interest, the mission
also will employ numerous ground-based systems, including those in
Maine, North Carolina, Georgia, Colorado and Virginia.
“It was surprising to find that while
lots of ground-based and orbital observations of the VLF
absorption/reflections/transmission had been made, there's not been
any measurements right in the region where all the action
happens. While we have good models of what to expect in
such regions, actual measurements are key to pin down the details of
those models, as well as to develop the instruments required to
explore more challenging regions,” said Bonnell.
The two-stage Terrier-Improved Malemute
rocket will carry the VIPER payload to an altitude of about 94 miles
before descending and landing in the Atlantic Ocean. The payload will
not be recovered.
