They had to quarantine for a month before lift-off.

While much of the world stays inside their homes during the COVID-19 pandemic, three astronauts launched away from Earth on a mission to the International Space Station.

NASA astronaut Chris Cassidy and two Russian cosmonauts, Anatoly Ivanishin and Ivan Vagner, arrived at the ISS on Thursday at 10:13 a.m. ET after lift-off in Kazakhstan. They're slated to spend about six months at the space station, to assist with research mission, Expedition 63.

The Exp 63 crew, with Chris Cassidy of @NASA and Anatoly Ivanishin and Ivan Vagner of @Roscosmos, entered their new home in space and joined the Exp 62 crew for a welcoming ceremony today. https://t.co/I5v5IMo3r7 pic.twitter.com/dGe4Z82pJ4

— Intl. Space Station (@Space_Station) April 9, 2020

Although part of the mission was planned well before the coronavirus outbreak, the astronauts had to spend one month in quarantine so they wouldn’t bring the virus to space.

"The health and welfare of the crew is always paramount," Courtney Beasley, communications specialist at NASA's Johnson Space Center, told CNN. "All of our crew must stay in quarantine for two weeks before they launch. This ensures that they aren't sick or incubating an illness when they get to the space station, and is called 'health stabilization.'"

NASA astronauts, currently preparing to head into space, spend their quarantine at Kennedy and Johnson Space Centers in Florida and Texas and only come into contact people that are pre-cleared by NASA flight surgeons. They spend their time self-isolating by preparing for the mission, — and like people staying on earth — studying, working out and making video calls to friends and family.

As an additional precaution, the astronauts that launched on Thursday were not allowed to say goodbye to their families in person before heading off to space.

At a televised press conference before the launch, Cassidy said not seeing his family was difficult, "but we realize that the whole world is affected by the crisis," he said, according to DW.

Those who were involved in working the launch maintained distances of six feet between each other.

The Exp 63 crew, with Chris Cassidy, Anatoly Ivanishin and Ivan Vagner, is nearing the station for a docking today at 10:15am ET. They lifted off from Kazakhstan at 4:05 am ET. #AskNASA | https://t.co/yuOTrZ4Jut pic.twitter.com/ZAypAZs0yQ

— Intl. Space Station (@Space_Station) April 9, 2020

Expedition 63 astronauts are researching biology, earth science, physical sciences, human research and biology at the ISS. Research collected during the mission will be used to extend human spaceflight beyond low-Earth orbit, continuing missions to the Moon and Mars.

Other astronauts who have been in space since well before the virus broke out are scheduled to land back on Earth on April 17 at a spaceport in Kazhakstan.