On November 4, 2019, at 10:10am German time, astronauts grappled the Cygnus 12 supply ship with the International Space Station’s robotic arm. Almost four tons of equipment for the ISS were on board.
Among them, the coolant system for the alpha magnetic spectrometer (AMS-02) built at RWTH Aachen University.
The particle detector AMS-02 was brought to the International Space Station in May 2011 with the last flight of the space shuttle Endeavour. Since then, the seven-ton spectrometer has been measuring cosmic ray particles with unprecedented precision and has already recorded 140 billion of them. These data provide new insight into the high-energy processes of the Milky Way and allow us to investigate questions about the nature of dark matter and the matter-antimatter asymmetry in the universe. More than 500 scientists from 16 countries worked on developing the 1.5 billion dollar experiment over more than 15 years.
The central element of AMS-02 is a silicon tracker that measures the trajectories of cosmic ray particles and is operated by a closed cooling circuit at a constant zero degree Celsius. The heat produced must be dissipated into space with a coolant system.
Three of the four redundant pumps in the coolant system, initially designed for three years of operation, have now failed after eight years.
Source: “New AMS Coolant System Arrived at the ISS”, RWTH Aachen University