(CNN)NASA Astronaut Christina Koch is returning to Earth after the longest single spaceflight by a woman.
Koch arrived on the International Space Station on March 14 for her spaceflight mission. She is scheduled to return Thursday after 329 days, breaking Peggy Whitson's record of 288 consecutive days in space.
Koch's is the second-longest single spaceflight by any US astronaut, NASA said in a release.
The hatch on the Soyuz MS-13 spacecraft closed Wednesday night as Koch prepared to return.
At 12:50 a.m. ET, the capsule, which will also carry Koch's fellow International Space Station expedition members, will undock. Around 3:18 a.m. ET, the aircraft will begin its deorbit burn. It is scheduled to land near Dzhezkazgan, Kazakhstan, at 4:12 a.m. ET.
In her historic trip to the station, Koch has orbited the Earth 5,248 times, conducted six space walks and spent a total of 42 hours and 15 minutes outside the station, the release said.
The mission will help NASA get ready to go to Mars.
"Koch's extended mission will provide researchers the opportunity to observe effects of long-duration spaceflight on a woman as the agency plans to return to the Moon under the Artemis program and prepare for human exploration of Mars," the release said.
This isn't the first time Koch has been a record breaker. In October, Koch and astronaut Jessica Meir conducted the first all-female spacewalk outside of the ISS. The spacewalk lasted for seven hours and 17 minutes, and the astronauts received a phone call from President Donald Trump as they completed the mission.
Koch said she hopes the record for longest spaceflight by a female astronaut will be exceeded again as soon as possible again, because it means "we're continuing to push those boundaries."
Speaking to CNN, Koch also offered a piece of advice to young girls who are pursuing their dreams.
"Do what scares you. Everyone should think about what intrigues them and what draws them in.
"Those things can kind of be scary a little bit, but they usually mean that you're interested. And if it's just outside what you think is attainable for you and you reach it, it really pays off dividends in more ways than one. It can be rewarding for you personally, and it usually means that you're giving something back to the world in the maximum way possible."