The Expedition 61 astronauts have one more spacewalk planned this weekend and they will finish the repair of a cosmic ray detector. This will be the ninth spacewalk for the crew, more than in any other increment in the history of the International Space Station.

NASA astronauts Jessica Meir and Christina Koch have turned their attention from Monday’s spacewalk to help two crewmates going on a very different spacewalk on Saturday. The pair completed a spacewalk yesterday upgrading power systems on the Port-6 truss structure.

Spacewalkers Andrew Morgan and Luca Parmitano of ESA (European Space Agency) will finalize thermal repairs on the Alpha Magnetic Spectrometer (AMS) on Saturday. The AMS, installed in 2011 on the Starboard-3 truss structure, is an astrophysics device searching for evidence of dark matter and antimatter.

The duo will set their U.S. spacesuits to internal power Saturday at 6:50 a.m. EST signifying the official start of their spacewalk. NASA TV begins its live broadcast of the planned six-hour AMS repair excursion at 5:30 a.m.

Meir and Koch will be getting up to speed this week with the Canadarm2 robotics procedures necessary to assist Morgan and Parmitano during Saturday’s spacewalk. The quartet gathered together Tuesday afternoon and began reviewing the spacewalk plan with specialists in Mission Control.