UNH Institute for the Study of Earth, Oceans, and Space

Launch Site for Cluster II

UNH Space Scientists Eagerly Await Aug. 9 'Cluster II' Launch

By Sharon Keeler UNH News Bureau

DURHAM, N.H. -- University of New Hampshire space scientists eagerly await the Aug. 9 launch of a pair of satellites in Kazakhstan. Two of their instruments are part of the Cluster II mission, a cooperative venture between the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA).

The original Cluster mission was lost on June 4, 1996, when the Ariane 5 rocket carrying the satellites exploded.

Artist's impression of the four Cluster II spacecraft flying in formation.

Cluster II consists of four identical spacecraft which will fly in formation 20,000 to 120,000 kilometers above Earth to study three-dimensional structures within the Earth's magnetosphere, or magnetic field. The magnetosphere is a protective boundary that helps prevent the solar wind, with its highly charged particles and billions of tons of ionized gas, from reaching Earth's surface.

"Cluster II will give scientists the best information yet on what happens when the solar wind interacts with this boundary," says Eberhard Moebius, professor of physics in UNH's Institute for the Study of Earth, Oceans, and Space, and lead investigator for one of the instruments."Picture a sheet, with something different going on on each side. The four satellites will allow us to have instruments on both sides of this boundary at the same time, and to distinguish between changes in space and time. It will be the first time this has been done."

The first two Cluster II satellites, Salsa and Samba, were successfully launched July 16. The next duo, Rumba and Tango, are scheduled for lift-off next week, and will join their companions Aug. 15 to form a unique space quartet. Once in orbit, they will spend two years passing in and out of the Earth's magnetosphere.

"Gun-detector units" for the Electron Drift Instrument (EDI). Each spacecraft carries two, mounted on opposite sides.

"Cluster II is part of an international program that, together with its 'sister' satellite SOHO (Solar Heliospheric Observatory), is designed to find out more about how the Sun and Earth interact," says Jack Quinn, research associate professor in UNH's Space Science Center. "While SOHO studies explosions on the Sun and detects solar storms heading toward Earth, Cluster II will measure the effects of this activity on near-Earth space as the incoming energetic particles buffet the Earth's magnetosphere."

Such data will help researchers better understand magnetic storms set off by solar flares and coronal mass ejections.These storms can disrupt satellite communication systems, power grids and radio transmission.

The Composition and Distribution Function (CODIF) Analyzer measures the energy, composition and number of ions in space

The 11 instruments aboard Cluster II represent the work of an international team of investigators. Among the instruments is the Electron Drift Instrument, or EDI, which will measure electric fields in the solar wind and the magnetosphere, and their boundary. An international collaboration for this instrument was lead by Germany's Max Planck Institute. Roy Torbert, professor of space physics, and Quinn are the project's UNH co-investigators and leaders of the American effort.

Also carried by Cluster II is the Composition and Distribution Function (CODIF) Analyzer, built by an international collaboration lead by the Centre d'Etude Spatiale des Rayonnements (CESR) in Toulouse, France. UNH professors Moebius and Lynn Kistler are directing the UNH effort associated with this instrument.

Second pair of Cluster spacecraft prior to mounting on the launch vehicle. UNH designed and built major portions of two different instruments for each of the four spacecraft. Parts of these and other instruments are seen protruding from the gold band around the top of each spacecraft

"CODIF measures the energy, composition and number of ions in space," says Kistler. "We will be studying how ions penetrate boundaries, both coming from the solar wind into the magnetosphere, and going outward from the magnetosphere."

UNH researchers have spent nearly 15 years planning the Cluster mission, developing instrumentation and building hardware. They will now spend the next several years analyzing the data it collects.

The launch of Cluster II's Rumba and Tango will be covered live on the Internet by ESA at http://clusterlaunch.esa.in.

Aug. 3, 2000

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