A NASA rocket mission, launching May 26, 2021, will study radio waves that escape through the Earth’s ionosphere impacting the environment surrounding 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 9:15 p.m., Wednesday, May 26. The launch
window is 9:15 p.m. to midnight EDT and the backup days are May 27-28. 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, and end up interacting with the high energy electrons
trapped in the Van Allen Radiation Belts,” said Dr. 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 (~4.4 Earth radii) out to 23,500 miles altitude (~7 Earth radii). GPS
satellites orbit at around 4.4 Earth radii, and geosynchronous satellites at
about 6.6 Earth radii. 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.
This plot shows altitude profiles of VLF absorption, proportional to the local plasma density times the electron-neutral collision frequency. The blue profiles show the nighttime conditions relevant for VIPER, and the red profiles show daytime conditions.
Credits: University of Colorado Boulder/Robert Marshall
By making accurate measurements of the VLF electromagnetic fields
and the properties of the ionosphere below, at, and above the absorption and reflection
layers in the ionosphere, VIPER provides a novel data set for comparison with
existing numerical models of the fields and the ionosphere, as well as
observations made in the past of the escaping VLF radiation at higher altitudes
and on the ground.
“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.
NASA's Van Allen Probes Find Human-Made Bubble
Shrouding Earth. Link to video: https://svs.gsfc.nasa.gov/12591
Live coverage of the mission will be available on the Wallops IBM video site (previously
Ustream) beginning at 8:55 p.m. on launch day.
The NASA Visitor Center at Wallops will not be open
for launch viewing.
Keith Koehler
NASA’s Wallops Flight Facility, Virginia
Source: https://www.nasa.gov/wallops/2021/feature/nasa-rocket-mission-studying-escaping-radio-waves
No comments:
Post a Comment