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NASA Launches THEMIS With Record Five Satellites Inserted In Orbit

By | February 19, 2007

      A NASA constellation of five satellites to study the Northern Lights were launched aboard a rocket from Pad 17B at Cape Canaveral Air Force Station, Fla.

      That launch occurred at 6:01 p.m. ET Saturday (the start of the window of opportunity) atop a Delta II rocket provided by United Launch Alliance, a joint venture of The Boeing Co. [BA] and Lockheed Martin Corp. [LMT]. Propulsion gear included three rocket stages and nine solid rocket motors.

      This was the first time NASA launched five satellites aboard a single rocket, a cosmic system called the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. (Please see full story in Space & Missile Defense Report, Monday, Jan. 22, 2007, page 6.)

      The spacecraft separated from the launch vehicle approximately 73 minutes after liftoff. By 8:07 p.m. ET, mission operators at the University of California, Berkeley, commanded and received signals from all five spacecraft, confirming nominal separation status.

      THEMIS will help resolve the mystery of what triggers geomagnetic substorms, according to NASA.

      Substorms are atmospheric events visible in the Northern Hemisphere as a sudden brightening of the Northern Lights, or aurora borealis.

      This is more than idle curiosity about the Northern Lights.

      Findings from the mission may help protect commercial satellites and humans in space from the adverse effects of particle radiation.

      The THEMIS satellite constellation will line up along the sun-Earth line, collect coordinated measurements, and observe substorms during the two-year mission. 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.

      “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 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 spacecraft to their final orbits in mid-September.

      During this 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.

      Swales Aerospace, in Beltsville, Md., built the THEMIS probes. THEMIS is an international project in partnership with Germany, France, Austria and Canada.

      The launch occurred after weather delays forced NASA to cancel prior launch plans, problems involving thunderstorms and winds. On Friday, with just a few minutes left to launch, a balloon signaled inhospitable upper-level winds, forcing a postponement.

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