NASA is no stranger to making history – but some breakthroughs take longer than others. Now, with the launch of NASA’s Crew-4 mission, the agency has finally hit a milestone long past due: Jessica Watkins, one of the four astronauts who left Earth for the International Space Station (ISS) early Wednesday morning, is the first Black woman to serve a long-term mission on board.

“I think it really is just a tribute to the legacy of the Black women astronauts that have come before me, as well as to the exciting future ahead,” Watkins told NPR in an interview Tuesday.

“For me, growing up, it was important to me to have role models in roles that I aspire to be in, contributing in ways I aspired to contribute,” she said. “So to the extent that I'm able to do that, I'm honored and grateful for the opportunity to return the favor.”

Despite the US being world -eaders in its number of world-leavers – indeed, depending on what percentage of the world’s GDP you own, going to space is more of a vacation than a vocation these days – precious few of those spacefarers have been people of color. In fact, almost nine out of every ten people who have been to space are white men, a statistic that is “reflective of the opportunities or roadblocks presented to different groups of people with a shared dream of space,” according to American space advocacy nonprofit organization Space Frontier Foundation.

“The fact that it’s taken this long to get African American folks on the ISS is disappointing. But it’s nice to see this focus is finally happening,” Kim Macharia, a Black woman who is the chair of the foundation’s board, told NBC.

“Less than 12 percent of all astronauts have ever been women, specifically. And then when you look at the number of people of color, the number is even lower there,” Macharia said. “So, there’s a lot of work to be done when it comes to addressing these demographics.”

Watkins is set to serve as mission specialist for Crew-4, NASA confirmed in a press release Wednesday. She will work closely with the commander and pilot to monitor the spacecraft during the launch and re-entry phases of flight, and will act as a flight engineer once aboard the ISS.

The mission is Watkins’s first trip to space, and only the fifth time a Black woman has reached that final frontier. The first Black woman to go to space was Mae Jemison, who made the trip in 1992 – a mere three decades after the first white man was sent there.

She was followed by Stephanie Wilson, who has logged more than 42 days in space – more than any other Black woman. Then went Joan Higginbotham, mission specialist onboard the space shuttle Discovery; finally, Sian Proctor made history on two accounts last year when she became the first Black woman to pilot a spacecraft during the first private crewed spaceflight mission.

Still, though, Watkins is no NASA novice. A geologist originally, she has studied the surface of Mars, and her previous experience includes working on the Mars Science Laboratory rover Curiosity. Her upcoming time on the ISS will include hundreds of scientific experiments, including “new and exciting scientific research in areas such as materials science, health technologies, and plant science,” Jason Costa explained for NASA, aimed at preparing for future space exploration and life on Earth.

“Experiments will include studies on the aging of immune systems, organic material concrete alternatives, and cardiorespiratory effects during and after long-duration exposure to microgravity,” Costa wrote. “These are just some of the more than 200 science experiments and technology demonstrations that will take place during their mission.”

The crew, traveling in a new SpaceX Dragon spacecraft they’ve named Freedom, are due to dock at the space-facing port of the ISS Harmony module around 8:15 p.m. Wednesday, April 27. 

NASA Television, the NASA app, and the agency’s website will all provide ongoing live coverage throughout. NASA also will cover the welcome ceremony for the new crewmembers, which will be held aboard the orbital outpost about 2:40 a.m. on Thursday, April 28.

“We have reached this milestone, this point in time, and the reason we’re able to arrive at this time is because of the legacy of those who have come before to allow for this moment,” Watkins said earlier this year of her history-making trip.

“Also, recognizing this is a step in the direction of a very exciting future,” she said. “So to be a part of that is certainly an honor.”