Today, NASA astronauts Peggy Whitson and Jack Fischer will perform the 200th spacewalk outside the International Space Station (ISS). Live coverage of the milestone event will begin in the stream above around 6:30AM ET, with the spacewalk itself scheduled to start 8AM and continue for six and a half hours.

For Fischer (wearing the space suit with no stripes), it will be a new experience — it’s his first ever spacewalk. But for Whitson, the commander on the current (and 51st) expedition to the ISS, it’ll be a familiar job. She holds the record for the most spacewalks by a female US astronaut, and today’s outing will be her ninth. The 57-year-old Whitson has also spent more days off the planet than any other woman (more than 500 days in total) and will be recognizable by the red stripes on her space suit.

The pair have a few different repairs to carry out while trussed to the exterior of the ISS. These include replacing a large avionics box that supplies electricity and data connections for various onboard science experiments, and installing a fabric shield designed to protect against micrometeorites on one of the spacecraft’s pressurized mating adapters. These adapters help connect different modules of the ISS. The one being worked on today, PMA-3, is currently installed on the Harmony module, where it will be used to host a new docking port for commercial crewed spacecraft arriving at the ISS.

For Whiston, today’s spacewalk also involves a little bit of unfinished business, albeit of the rather unglamorous kind. The fabric shield she and Fischer will be installing is a replacement for one that Whitson lost on a previous spacewalk. The shield is about two inches thick and measures about five feet by two feet. It’s part of an array of measures that protect the ISS against space debris, ensuring that the events of 2013 film Gravity don’t play out in real life.