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1,364 pounds (620 kg) each
Data downlink:
720 kilobits per second
Power consumption:
596 watts (average)
icon Observatory and Instruments

Launch Vehicle

The Delta II expendable launch vehicle is the product of a long evolution that dates back to the earliest days of American missile development. Use of proven components and gradual modification of those components has resulted in one of the most reliable launch vehicles in the world.

Over its forty-six-year life span, the Delta family of expendable launch vehicles has racked up what is perhaps the most successful flight record of any rocket currently in service. Of 317 flights, only 15 have been total failures, a success rate of 95.2 percent. The Delta II has had only one total failure (and one partial failure, Koreasat-1) since its first launch in February 1989 — an incredible 99% success rate — and is currently in its longest streak ever of consecutive successes, with Delta 324 being the 73rd success in a row.


Twin Observatory Design

The STEREO mission includes two nearly identical spacecraft designed, built and operated by The Johns Hopkins University Applied Physics Laboratory (APL) for NASA Goddard Space Flight Center, which manages the mission. The twin observatories each carry two instruments and two instrument suites for a total of 16 instruments per observatory. The scientific instruments come from institutions around the world, including the Naval Research Laboratory; the university of California at Berkeley; the university of New Hampshire; and the Paris Observatory. Onboard each spacecraft, six operational subsystems support the instruments and instrument suites. The subsystems include: command and data handling, radio frequency communications, guidance and control, propulsion, power, and thermal. Each of the two solar-powered, 3-axis-stabilized spacecraft have a launch mass - including propellant - of approximately 1,412 pounds (642 kilograms). The spacecraft will communicate with the APL-based mission operations center via NASA's Deep Space Network. Artist's concept illustrating deployment of the twin observatories' panels shortly after the spacecraft separate from the launch vehicle.