WASHINGTON – "You're right now on television all over the world so don't get nervous," President Donald Trump told two female NASA astronauts for conducting the first-ever all-female spacewalk Friday in a mission to replace a failed power control unit.
Christina Koch and Jessica Meir stepped outside the International Space Station just before 8 a.m. EST Friday and planned to spend more than five hours replacing the regulator, which controls how much energy flows from the station's massive solar panels to battery units.
The president called the two women, who were still outside the station completing the replacement, from the White House Roosevelt Room on Friday.
"Station, this is President Donald Trump. Do you hear me?" he said. After a brief pause, the women responded. "That's great, I was starting to get worried about you," he said, seated between Vice President Mike Pence and his daughter, Ivanka Trump.
Trump repeatedly called the women “brave.”
The two astronauts, who are both part of the 2013 NASA class, appeared to correct Trump after he suggested it was the first time a female astronaut had gone on a spacewalk.
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“This is the first time for a woman outside of the space station,” Trump said. “They’re conducting the first ever female spacewalk to replace an exterior part of the space station.”
Russian astronaut Svetlana Savitskaya was the first woman to walk in space in 1984.
"We don't want to take too much credit because there have been many other female spacewalkers before us. This is just the first time there have been two women outside at the same time," one of the women told the president.
The call was the first time since 1969 that a U.S. president has spoken to astronauts while they were outside the station, according to the White House.
President Richard Nixon called Neil Armstrong and Edwin "Buzz" Aldrin, who were on the moon, in what some referred to at the time as the longest-distance telephone call ever placed.
“What you do is incredible," Trump said."You're very brave people. I don't think I want to do it."
Meir said she and Koch had been training for about six years and the landmark mission was her first spacewalk. She said the pair have been in space for about three weeks.
"For us it's just coming out here and doing our job today, and we were the crew that was tasked with this assignment," Meir said.
"At the same time we recognize that it is a historic achievement and we do of course want to give credit for all of those that came before us. There have been a long line of female scientists, explorers, engineers and astronauts. And we have followed in their footsteps to get us where we are today."
The units have previously been replaced using a robotic arm, but the newly failed unit is too far for it to reach.
Contributing: Adrianna Rodriguez
This article originally appeared on USA TODAY: NASA all-female spacewalk: Trump calls Christina Koch, Jessica Meir