The first two satellites launched successfully July 16 from Baikonur Cosmodrome in Kazakstan, Russia. A project of the European Space Agency, Salsa and Samba were launched on a Soyuz-Fregat launch vehicle provided by the French-Russian consortium, Starsem. Another pair of identical satellites, Tango and Rumba, are scheduled for launch Wednesday.
Together the four satellites, dancing in a tetrahedral formation during their two-year mission, will give three-dimensional views of the near-Earth particle, field and plasma environments.
Orbiting in an elliptical polar orbit, the four spacecraft will examine how particles from the Sun interact with the Earth's magnetic field, observing magnetic and electrical interactions through direct measurements of the fields and particles trapped in the Earth's magnetic field. For the first time, small-scale fluctuations in interplanetary space will be measured between each of the four spacecraft as they orbit the Earth.
Los Alamos' imaging spectrometers will measure the fluxes of energetic electrons encountered at the satellites.
Los Alamos Cluster team leader Richard Belian of the Space and Remote Sensing Sciences group and his colleagues have invested years of research and development into their equipment. Their current success is all the more poignant in the wake of the disastrous failure of the Arianne IV rocket during the original launch of the Cluster I mission in 1996.
The instrument packages aboard the satellites will gather information on the magnetic storms, electric currents and particle accelerations that take place in the space surrounding Earth. These features produce events such as the aurorae in the polar regions, and under extreme conditions can create power outages, breakdowns in telecommunication systems, satellite malfunctions and perhaps even changes in climate.
"The Cluster formation will remove, for the first time, temporal and spatial ambiguities in the interpretation of magnetospheric data," said Belian. "Until now, with single or even double satellites, we have been unable to determine whether an event, say an enhancement of the energetic-particle flux, was due to the passage of a structure (a spatial event), or whether the flux simply changed (a temporal event). This aspect pertains to every kind of measurement that Cluster will make."
The Los Alamos spectrometer was built as part of the instrument called RAPID (Research with Adaptive Particle Imaging Detectors). RAPID measures very energetic electrons and ions, which need separate instruments, and Los Alamos was tasked with building the electron part -- the Imaging Electron Spectrometer.
"Up until now most space physics missions have been based on single satellites that can only measure a single point in space and then infer the conditions in the surrounding area. This is the first mission designed to use multiple satellites to simultaneously measure the conditions across an entire region of space. That should give us our first really good look at the three-dimensional structure of the magnetosphere and how charged particles and energy flow through Earth's space environment," said Geoff Reeves, a member of the team and leader of the Space and Atmospheric Sciences group at Los Alamos.
Work on both the Cluster I and Cluster II missions was jointly sponsored by the European Space Agency and NASA.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.