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Sweden's Prisma satellites go their separate ways

Posted: August 11, 2010

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Two small Swedish satellites split apart Wednesday, commencing several months of trials in orbital formation flying and rendezvous techniques using sensors from across Europe.

The Tango (top) and Mango (bottom) satellites pictured during testing before launch. Credit: Swedish Space Corp.
The Prisma satellites, nicknamed Mango and Tango, separated at 1751 GMT (1:51 p.m. EDT) Wednesday as they orbited nearly 500 miles above Earth. The maneuver went as planned, according to a posting on the mission website.

"We had all reason to open the champagne: telemetry indicated that Tango was free flying and had stabilized itself in a slowly rotating sun pointing attitude. Battery was nominal and solar array is working," said an update on the Prisma website.

Tango, the smaller of the two satellites, is about the size of a microwave. With a mass of 88 pounds, Tango has fixed solar panels and acts as the target during Prisma's demonstrations.

The active spacecraft is named Mango, a 331-pound satellite with the dimensions of a typical kitchen stove. Mango is outfitted with conventional hydrazine and exotic green propellant maneuvering systems.

In the two months since launch, controllers have powered up the satellites' navigation and formation flying equipment, tested its green propellant thruster, and successfully navigated around orbital debris threats.

"Prisma is really a Christmas tree of different demonstrations," said Staffan Persson, Prisma project manager at Swedish Space Corp., in an interview before the mission's June 15 launch.

The Prisma mission carries a smorgasbord of payloads from across Europe, including autonomous rendezvous technology from Sweden, a GPS system from Germany, a radio frequency instrument from France, and a vison-based navigation sensor from Denmark.

Read our previous story for more details on Prisma's objectives.

Each system has its strengths, and the two satellites will rely on the navigation instruments to repeatedly approach each other from long distances. Some of the demos will finish with Mango and Tango less than 1 meter, or about 3 feet, from each other.

"The priorities are to demonstate autonomous formation-flying, meaning that we regard these two satellites as one entity," Persson told Spaceflight Now in June. "So they are supposed to keep a fixed position relative to each other without ground control in the loop."

The technologies tested by Prisma could be flown on future space missions requiring precise orbit control and formation flying.

The mission is expected to last until next spring.