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ISS astronauts succeed in fixing $2 billion ‘unserviceable’ instrument

Astronauts aboard the International Space Station (ISS) have completed a 6-hour spacewalk to finish repairing a dark matter detection instrument which was previously considered “unserviceable.”

Yesterday, NASA astronaut Andrew Morgan and European Space Agency astronaut Luca Parmitano spent 6 hours and 16 minutes outside of the ISS, performing repairs to the Alpha Magnetic Spectrometer (AMS). The AMS was installed in 2011 for a huge cost of $2 billion, but it was only scheduled to last for three years of operation. In the original design, the AMS was to be shut down after its three year period, so it was not designed to be serviced by the astronauts.

NASA astronauts
NASA astronauts Christina Koch (foreground) and Jessica Meir assist spacewalkers Luca Parmitano (left) and Andrew Morgan (right) before beginning the spacewalk NASA TV

However, the AMS proved its worth as a highly valuable tool in researching dark matter, so the space agencies decided they would attempt to repair it. This required the training of the astronauts on entirely new procedures and the fabrication of new tools as the original fittings were not compatible with the standard tools used on spacewalks.

In total, it took four spacewalks to repair the AMS, with the first happening in November last year and the fourth happening this weekend. The aim of the spacewalks was to upgrade the cooling system on the AMS, as two of its four cooling pumps had stopped working. As well a the installation of the new cooling system, power and data cables had to be added to connect it to the instrument, requiring high-precision work of cutting and installing stainless steel tube cooling lines.

Yesterday, Morgan and Parmitano checked the cooling system for leaks, finding one slight leak which was fixed by tightening the fittings and opened a valve to pressurize the system. All seems to have been successful, as NASA reports that, “Preliminary testing shows AMS is responding as expected.”

In order to prepare the AMS to resume science operations, the system needs to be stabilized by filling the thermal control system with carbon dioxide, then the pumps must be powered on and checked. At least one part of the AMS, the silicone tracker which detects the curvature of particles as they pass through the detector, should be operating once more by the end of next week.

With its new cooling system in place, the AMS should be able to collect scientific data for many more years to come, with NASA announcing, “The upgraded cooling system is expected to support AMS through the lifetime of the space station.”

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