NASA is about to announce the 8 astronauts who will fly SpaceX and Boeing's spaceships for the first time - here's who they might be

Doug Hurley, Eric Boe, Bob Behnken, and Sunita "Suni" Williams are seasoned spaceflight veterans who've worked with Boeing and SpaceX for years to test and provide feedback on their ships. They know the spacecraft inside and out and are well equipped to handle any kind of anomaly or emergency.

Here's what to know about them.

Williams grew up in Massachusetts, is a Navy veteran, and has been a NASA astronaut since 1998. She has flown inside three different spaceships on two missions, served as commander of the International Space Station, lived in orbit for 322 days, and in her previous career, piloted 30 different types of aircraft.

She's also been providing crucial feedback to Boeing and SpaceX as part of NASA's Commercial Crew Program.

"Five years ago, this would have been like, 'No way, what are we doing asking commercial providers to be able to do this?'" Williams previously told Business Insider. "Now it feels like a natural progression for space travel."

Selected as an astronaut in 2000, Behnken has flown twice into orbit on NASA's space shuttle Endeavour. He's also an experienced Air Force ROTC test pilot with more than 1,500 hours of flight on 25 different aircraft.

Like Williams, he's worked hand-in-hand with Boeing, SpaceX, and NASA to improve the Crew Dragon and CST-100 Starliner spaceships, so he's well-equipped to fly them.

He also understands the risks of spaceflight first-hand: Behnken was waiting near the runway on which space shuttle Columbia was supposed to land when he heard that the ship had broken apart during atmospheric reentry, killing its seven-member crew.

Boe, who was selected as an astronaut in 2000, is arguably one of the most experienced pilots in the Commercial Crew Cadre.

Boe is a retired Air Force colonel and test pilot with more than 6,000 hours inside 50 different aircraft, and he has also piloted two space shuttle missions to and from orbit around Earth.

Hurley is also a two-time space shuttle pilot and was also selected in 2000 by NASA.

Like Behnken and Boe, Hurley was a test pilot in the military. He logged more than 5,000 hours in 25 different aircraft for the Navy. Boe has spent the past three years working on the Commercial Crew Program to provide ideas, hands-on testing, and feedback — so he's intimately familiar with both spacecraft.

Beyond the Commercial Crew Cadre, we already know one space-flyer for certain: Ferguson.

He's not one of NASA's eight picks. Instead, he's slated to become the first "corporate astronaut" as a third crewmember on a Boeing test flight, according to the Washington Post.

Ferguson is a retired NASA astronaut who's now on Boeing's payroll. He's a logical pick, since he's worked on the CST-100 Starliner program for many years, and was also a space shuttle commander, space shuttle pilot, and Navy test pilot.

It's currently anyone's guess (other than NASA's) who the other four Commercial Crew Program astronauts might be.

However, Epps may be a likely pick. She was selected as a NASA astronaut in 2009 and hasn't yet flown into space — though she was training to do so until very recently.

Epps was assigned to fly to the space station as part of the Expedition 56 and 57 mission, which launched in June. But without any public explanation in January, NASA pulled Epps from the flight. As recently as June 25, Epps said she still didn't know the reason why.

However, NASA is historically cagey about its decisions, and one possible explanation is that the agency saw something in her that it needed for a Commercial Crew Program flight. Whatever the case, Epps is active and eligible for selection.

Fincke, who was selected in 1996, is not part of the Commercial Crew Cadre. But the astronaut has been working on the program for many years. He's also a three-time spaceflight veteran with more than 381 days logged in orbit.

Cassidy is a US Navy captain with 10 years of experience as a Navy SEAL. Cassidy was selected by NASA as an astronaut in 2004 and has since flown on two space missions.

He also has first-hand experience with surviving trouble in space. In 2013, Cassidy was outside the space station when water began leaking into his helmet, and he had to scramble back to an airlock to avoid being drowned in microgravity.

A Kentucky native, Bresnik was selected by NASA in 2004. He's flown to space twice, and prior to his astronaut career, he was a US Marine Corps colonel and test pilot with more than 6,000 hours flying in 83 different aircraft.

Glover was selected by NASA as an astronaut in 2013 and completed his training two years later. Though he has yet to visit space, he's no rookie to flying: He remains a test pilot and commander in the US Navy. Glover has flown more than 2,000 hours in 40 aircraft, has made 400 landings on an aircraft carrier, and completed 24 combat missions.

Since her selection by NASA in 2009, Rubins has gained experience with test flights, having flown on the first launch of Russia's Soyuz MS spacecraft in July 2016. She returned to Earth in October after logging 115 days in orbit.

Wheelock has been a NASA astronaut since 1998 and flown on two missions. He's also a retired US Army colonel with more than 7,000 flight hours inside 46 different aircraft and spacecraft.

It's hard to say which eligible candidates NASA will pick, but any of the following 21 astronauts (who were not previously listed) could be named on Friday.

Click each of their names below to read their NASA biography.

• Joseph M. Acaba
• Michael R. Barratt
• Stephen G. Bowen
• Josh A. Cassada
• Tracy Caldwell Dyson
• Robert Shane Kimbrough
• Kjell N. Lindgren
• Nicole A. Mann
• Thomas H. Marshburn
• K. Megan McArthur
• Anne C. McClain (who gained attention earlier this year for her adorable astronaut portrait shoot)
• Jessica U. Meir
• Karen L. Nyberg
• Donald R. Petitt
• Walker Shannon
• Scott D. Tingle
• Mark T. Vande Hei
• Jeffrey N. Williams
• Barry E. Wilmore
• Stephanie D. Wilson
• Reid G. Wiseman