After 328 days aboard the International Space Station (ISS), Christina Koch will make her departure early on Thursday morning (EST). Her mission will be celebrated as the longest single spaceflight by any woman, and the second-longest of any US astronaut.

Returning alongside European Space Agency (ESA) astronaut Luca Parmitano and Russian cosmonaut Alexander Skvortsov, who will have both spent 201 days aboard the ISS during this trip, Koch’s first spaceflight will have spanned three expeditions (59, 60, and 61). Expedition 62 will commence when the Soyuz MS-13 spacecraft carrying the three astronauts undocks at 12.50am EST (5.50am GMT) on Thursday, February 6, 2020.

As with all astronauts, Koch’s time in space has been incredibly valuable to understanding how the human body is affected by spaceflight. Amassing a total of 5,248 orbits of Earth, covering 223 million kilometers (139 million miles) – roughly the equivalent of traveling to the Moon and back 291 times – Koch’s long-duration mission provides an opportunity to research the variability of the human response to spaceflight.

Amongst the 210 investigations Koch has participated in, is the Vertebral Strength investigation, which improves our knowledge of bone and muscle degradation of the spine during spaceflight. Koch’s participation during her time aboard the ISS will help to advance NASA’s aim of returning humans to the Moon (Artemis program), and may even inform human exploration of Mars.

As well as breaking Peggy Whitson’s previous record of 288 continual days in space, Koch, alongside fellow NASA astronaut Jessica Meir, made history in October 2019 when they carried out the first all-women spacewalk. Which, you may remember, was postponed from March 2019 due to the lack of suitable suits.

Astronauts Christina Koch (foreground in suit with stripes) and Jessica Meir (suit with no stripes) carrying out the first all-female spacewalk on October 18, 2019. NASA TV

“Highlighting it was the first all-female EVA, [or] spacewalk, is important because seeing those milestones be broken tells people where we are at and where we think the importance lies,” Koch told CBS News. “I think it’s inspiring because future space explorers do need to see people who remind them of themselves.”

However, this was not the only time Koch floated out of the ISS. In total, she spent 42 hours and 15 minutes fixing the station over the course of six spacewalks. In this time she helped to upgrade the station’s power system.

Inside the ISS, Koch also contributed to a long line of scientific experiments. Growing leafy greens to understand how the spaceflight environment impacts plant biology; studying kidney health to help find better treatments for kidney-related conditions on Earth; 3D-printing biological tissues to possibly make human organs in space viable; crystallizing a membrane protein to support the development of cancer treatments; and even baking cookies.

Christina working with the BioFabrication Facility to print organ-like tissues. NASA

Koch’s venture to space will end at 4.13am EST (9.13am GMT) when the Soyuz undergoes a parachute-assisted landing in Kazakhstan. After undergoing preliminary medical evaluations the astronauts will begin their rehabilitation and reconditioning programs, before they return to their homes.

Speaking to CBS News about her achievements ahead of her return, Koch said “I’d have to say that my number one hope for this milestone is that the record is exceeded again as soon as possible. Because that means that we’re continuing to push the boundaries.”

You can watch the astronauts return to Earth via NASA’s live-stream.

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