NASA is
readying five small satellites to launch spaceward next month on a mission to
pinpoint the source of aurora-boosting storms from Earth's magnetic field.
The
spacecraft quintet is part of NASA's THEMIS mission to find the trigger point
of geomagnetic substorms, which begin somewhere in the Earth's magnetic field
and, within minutes, swoop inside the Moon's orbit to the planet's upper
atmosphere and brighten the aurora borealis - also known as the Northern
Lights. The speed of the substorms makes tracking their starting point
impossible with a single spacecraft, mission researchers said.
"Finding
the elusive substorm point of origin is a question almost as old as space
physics itself," THEMIS principal investigator
Vassilis Angelopoulos, of the University of California at Berkeley, told
reporters in a Wednesday teleconference. "[The mission] is a stepping stone
towards understanding space weather phenomena that affect our lives."
A United
Launch Alliance Delta 2 rocket is slated to loft the THEMIS mission, which is
short for the lengthy moniker Time History of Events and Macroscale
Interactions during Substorms, on Feb. 15 during a 19-minute window that opens
at 6:07 p.m. EST (2307 GMT) [image].
The $200 million mission, the launch of which has been delayed since October
due to booster issues, is named for the Greek goddess of justice, NASA
officials said [image].
"We look
forward to some terrific scientific discoveries," THEMIS project manager Peter
Harvey, also of UC Berkeley, told reporters.
First
identified in the 19th century, geomagnetic substorms are recurring
phenomena spawned by a sudden release of charged particles - collected from the
Sun's solar wind - in the Earth's magnetic field. The high-energy particles
follow the Earth's magnetic field lines until they strike the upper atmosphere,
giving a boost to the Northern Hemisphere's aurora borealis, researchers said.
While a
substorm's aurora amplification seems like a limited visual effect, a series of
such storms can occur during major space weather events that interfere with
communications satellites or pose risks to astronauts in orbit, Angelopoulos
said.
Only four
THEMIS satellites are required to complete a primary two-year mission [image].
After reaching orbit, two of the probes will be sent on a trajectory that
carries them about one-sixth of the way to the Moon while two others take up
stations about halfway to the Moon. The spacecraft will line up with one
another and ground stations on Earth every four days during their respective
orbits, researchers added [image].
The fifth
THEMIS satellite is a spare in case one of its counterparts fails during the
initial two-year mission.
"We're
flying five to increase our reliability," Angelopoulos said.
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