Five Satellites Launched to Study Geomagnetic Substorms
For the first time, NASA has launched five satellites aboard a single rocket from Cape Canaveral.
The mission will help resolve the mystery of what triggers geomagnetic substorms. Substorms are atmospheric events visible in the Northern Hemisphere as a sudden brightening of the Northern Lights, or aurora borealis. The findings from the mission may help protect commercial satellites and humans in space from the adverse effects of particle radiation.
It is known as the THEMIS mission for the “Time History of Events and Macroscale Interactions during Substorms.”
During the next two years, THEMIS’ satellite constellation will line up along the Sun-Earth line, collect coordinated measurements, and observe substorms. Data collected from the five identical probes will help pinpoint where and when substorms begin, a feat impossible with any previous single satellite mission.
“The THEMIS mission will make a breakthrough in our understanding of how Earth’s magnetosphere stores and releases energy from the sun and also will demonstrate the tremendous potential that constellation missions have for space exploration,” said Vassilis Angelopoulos, THEMIS principal investigator at the University of California, Berkeley.
Angelopoulos says that THEMIS’ unique alignments also will answer how the Sun-Earth interaction is affected by Earth’s bow shock, and how “killer electrons” at Earth’s radiation belts are accelerated.
The bow shock is the boundary at which the solar wind abruptly drops as a result of its approach to the Earth’s magnetic envelope. The Earth’s bow shock is about 100 to 1,000 km (60 to 600 mi.) thick and located about 90,000 km (56,000 mi.) from the Earth.
The Mission Operations Center at the University of California, Berkeley, will monitor the health and status of the five satellites. Instrument scientists will turn on and characterize the instruments during the next 30 days. The center will then assign each spacecraft a target orbit within the THEMIS constellation based on its performance. Mission operators will direct the spacecraft to their final orbits in mid-September.
During the mission the five THEMIS satellites will observe an estimated 30 substorms in process. At the same time, 20 ground observatories in Alaska and Canada will time the aurora and space currents.
The relative timing between the five spacecraft and ground observations underneath them will help scientists determine the elusive substorm trigger mechanism.