Boeing and NASA launch Starliner spacecraft

NASA Astronaut Suni Williams. Robert Markowitz/NASA

With this flight, Suni Williams, who was selected as a NASA astronaut in 1998, will make a bit of history as the mission's pilot. Few women have joined the first flight of a new spacecraft.

And it won't be her first entry in the history books.

In 2012, during a prior trip to the International Space Station, Williams became the first person to finish a triathlon in space, during which she simulated swimming using a weight-lifting machine and ran on a treadmill while strapped in by a harness so she wouldn't float away.

That came after she ran the Boston Marathon from the space station in 2007.

Williams — a native of Needham, Massachusetts — has also spent ample time outside the space station.

During her previous missions, she notched a total of 50 hours and 40 minutes across seven spacewalks, ranking second among female astronauts.

Williams also gave a detailed tour of the space station in 2012, even showing the "orbital outhouse" (aka bathroom). Watch that here.

Ahead of this mission, Williams told reporters that she wasn't nervous about making the jump from test piloting aircraft to spacecraft.

Williams has traveled to space twice before, once on a NASA space shuttle in 2006 and again on a Russian Soyuz capsule in 2012. She's logged 322 total days in space.

NASA astronaut Butch Wilmore arrives at the Kennedy Space Center, in Cape Canaveral, Florida, on April 25.  Paul Hennessy/Anadolu/Getty Images

For Starliner's debut launch, NASA is sticking with a long tradition of staffing the novel spacecraft with astronauts who have previously trained as military test pilots: Sunita "Suni" Williams and Barry "Butch" Wilmore.

All that time piloting experimental aircraft just might give these astronauts the proverbial "right stuff."

"They're checking out a lot of the systems: the life support, the manual control," NASA chief Bill Nelson said during a May 3 news conference. "That's why we put two test pilots on board — and of course the resumes of Butch and Suni are extensive."

Wilmore — a Tennessee native and Navy test pilot — has spent more than 8,000 hours of his life aboard tactical jets, according to NASA.

Before he was selected for NASA's astronaut corps in 2000, Wilmore was on exchange as flight test instructor at the Air Force Test Pilot School in California.

As an astronaut, Wilmore has already logged 178 days in space during two separate missions and conducted four spacewalks.

Wilmore once recalled a spacewalk experience during a 2018 acceptance speech for the NCAA Theodore Roosevelt Award. (Wilmore played football at Tennessee Technological University as an undergrad.)

Wilmore said that, during the spacewalk, he was surprised to find that a radiator on the space station's exterior was reflective, like a mirror.

In this screen grab from video, NASA astronauts Butch Wilmore and Suni Williams are seen during launch preparations in Cape Canaveral, Florida, on June 1. NASA TV

The hatch has officially closed, and NASA astronauts Butch Wilmore and Suni Williams are ensconced inside the Starliner crew capsule ahead of launch.

Now, teams will conduct leak checks to make sure Starliner is ready for flight.

In this screen grab from video, Boeing’s Starliner spacecraft is seen in Cape Canaveral, Florida, on June 1. NASA TV

The countdown to Starliner's launch this morning was progressing smoothly until teams discovered a hiccup around 10 a.m. ET.

Mission teams reported a loss of data from ground valves responsible for replenishing the liquid oxygen and hydrogen to the second, or upper stage, of the Atlas V rocket.

Both liquid oxygen and hydrogen, used to fuel the rocket, boil off as the rocket sits on the pad ahead of launch, so replenishment is ongoing until liftoff.

After evaluating the issue, which prevented the hatch from closing after the astronauts entered the crew capsule for about 45 minutes, mission teams switched to a redundant system for the valve data.

Then, teams resumed replenishing liquid hydrogen and oxygen.

Fortunately, mission teams were ahead of the expected timeline when the issue occurred, and the countdown to launch has resumed, according to the live NASA broadcast. And the issue never posed a threat to crew safety.

Starliner was only about two hours from its first crewed launch attempt on May 6 when engineers identified an issue with a valve on the second stage, or upper portion, of the Atlas V rocket. The entire stack, including the rocket and spacecraft, was rolled back from the launchpad for testing and repairs.

Then, mission teams reported a small helium leak within the spacecraft service module. The leak was traced to a part called a flange on a single reaction control system thruster, where helium is used to allow the thrusters to fire.

The space agency determined the leak did not pose a risk to the flight.

While evaluating the helium issue over the past two weeks, engineers also spotted a “design vulnerability” in the propulsion system — essentially identifying a remote scenario in which certain thrusters might fail as the vehicle leaves Earth’s orbit, without a backup method of getting home safely.

NASA and Boeing have since worked with the vendor of the thruster to come up with a backup plan to perform the deorbit burn, should that situation arise, Stich said in a May 24 news conference.

“We have restored that redundancy for the backup capability in a very remote set of failures for the direct burn,” Stich said.

The mission teams also took a close look at Starliner’s parachutes after one parachute on Blue Origin’s recent suborbital crewed flight failed to fully inflate. Starliner uses components that are similar to that parachute system, Stich said.

Blue Origin shared flight data with Boeing and NASA, and after assessing Starliner’s parachutes, the team deemed them “good to fly.���

Boeing's Starliner spacecraft sits on the launchpad during sunrise in Cape Canaveral, Florida, on June 1. Chris O'Meara/AP

At the launch site, weather officials have given a 90% chance that conditions will be clear for liftoff.

So far, the only potential concerns are winds and cumulus clouds, said Mark Burger, launch weather officer for the 45th Weather Squadron at Cape Canaveral Space Force Station.

"They're watching the ground winds, which are really stronger than normally we would have expected, but we've got strong onshore flow from a high pressure system that's just off the coast of North Carolina," said Derrol Nail, launch commentator for NASA. "Overall though, we couldn't be in a better position."

According to weather constraints shared by Boeing, Starliner can't take off if cumulus clouds with frozen tops are within 5 to 10 miles (8 to 16 kilometers) of the launchpad.

High winds could trigger an abort after launch, which could be a problem for the parachute-assisted landing the capsule would try to make.

"If there were a problem with the rocket, the capsule could pull off and abort and fly over the shore and land in the water," said NASA astronaut Mike Fincke. "If the winds are too strong, it'll make it land on the beach. And that sounds like it would be safe but actually, we're not sure that structurally would work and we're set up to land on the water so the winds can't be too strong or they'll push us for an abort. So, if we if we start to get into where the winds would push the capsule too much, then we'll we'll wait until another day."

In this handout photo from NASA, a United Launch Alliance Atlas V rocket, with Boeing’s Starliner spacecraft aboard, is seen on the launchpad at Cape Canaveral Space Force Station in Florida on June 1. Joel Kowsky/NASA

After a decade of development and years of delays, the time has finally arrived: Boeing's Starliner spacecraft is set to take off from Cape Canaveral Space Force Station in Florida at 12:25 p.m. ET.

If successful, this mission — dubbed the Crew Flight Test — could pave the way for NASA to clear the Starliner for routine operations, giving the United States for the first time two domestic options for ferrying astronauts to the International Space Station. (Currently, NASA must use either SpaceX's Dragon or a Russian Soyuz spacecraft for these missions.)

But this is still considered a test run.

Suni Williams and Butch Wilmore are veteran NASA astronauts who will be on board and prepared to take over the autonomous Starliner vehicle if something goes wrong.

Today, the Starliner will launch to space atop an Atlas V rocket before the spacecraft breaks away after reaching orbit.

The Starliner will then begin firing its own engines, and Williams and Wilmore are expected spend more than 24 hours aboard the 15-foot-wide, gumdrop-shaped vehicle as it makes its way to the space station.

If everything goes according to plan, the Starliner is expected to dock around 1:50 p.m. ET Sunday. 

Williams and Wilmore expect to spend eight days inside the orbiting laboratory, joining the seven astronauts and cosmonauts already on board.

After that, they'll get back on Starliner and make the trek home, aiming to land at one of several potential sites across the southwestern United States.