Christina Koch and Jessica Meir were selected by NASA for their academic brilliance, ability to handle pressure, and overall resilience during missions to replace a power controller that has been failing to respond. The spacewalk was supposed to happen at an earlier date with an astronaut named Anne McClain instead of Meir, but a lack of properly sized extra-vehicular mobility units postponed the operation. The EMU suits are equipped with a massive amount of tech to keep the astronaut alive, and maintaining pressure inside requires that the suit fits its wearer well. The EMU needs to regulate gases around the body as well as protect it from radiation and supply it with oxygen. Astronauts have to invest hours into training with the suits on due to their bulkiness, so allowing McClain to wear one a size too large was not an option. The mission will still feature an all-woman team, paving the way for more representation within NASA.