TUBSAT-B was the first earth observation satellite of TU Berlin. Successfully launched as a secondary payload onboard a Tsyklon 3 on January 25, 1994 from Plesetsk, Russia. It reached a medium orbit of 1250km altitude at 82deg inclination. The main payload is a Meteor 3-7, a USSR/Russian Federation weather satellite. The launch has been sponsored by Kayser-Threde GmbH, Germany. Unfortunately the satellite was lost after 39 days in orbit. The cause for the failure could never be determined definitively. The most probable cause is radiation damage due to the satellite’s position in the inner van-Allen Belt. Nevertheless most experiments on board could be performed. The principal objective of TUBSAT-B was space technology experimentation with a focus on the demonstration of a high resolution attitude control system for microsatellites using a star sensor and three reaction wheels.