UPDATE: May 23, 2017, 10:15 a.m. EDT Whitson and Fischer just finished up their urgent spacewalk outside the International Space Station, and it was a success. The newly-installed communications box is functioning well. The spacewalk lasted two hours and 46 minutes, ending at 10:06 a.m. ET. Our original story follows below.

Two astronauts stepped out into the void of space this morning to repair a critical piece of hardware on the International Space Station during a quickly-planned “contingency” spacewalk.

NASA’s Peggy Whitson and Jack Fischer are, at the time of this writing, floating around outside the Space Station to replace a faulty electronics box known as a Multiplexer-Demultiplexer (MDM) that failed on Saturday. As Whitson repairs the MDM, Fischer will work to install some antennas on the outside of the station, a leftover task from the last spacewalk on May 12.

While no astronauts or cosmonauts were ever in danger due to the broken MDM, which helps keep key electrical systems like the solar arrays working, NASA wanted to be sure to fix this issue as soon as possible in order to be sure that if anything were to go wrong with the currently functioning electronics box, they would have a backup in place. It’s all about redundancy, you see. 

Spacewalks are some of the most dangerous activities astronauts can do in space. Instead of staying within the relative safety and comfort of the station, astronauts that venture out into space are only protected by their suits as they move through the void of space.

Thanks to the wonders of technology and the American space program, we can also watch the spacewalk live online. Check out the spacewalk, which is expected to run about 2.5 hours, in the window below.

This marks Whitson’s 10th career spacewalk, extending her record as the woman with the most spacewalks under her belt. If all goes according to plan, Whitson should also move into third place for overall spacewalking time as a NASA astronaut.

The Tuesday spacewalk is Fischer’s second. His first was on May 12 when he and Whitson ventured outside the station to perform some routine maintenance.