Thursday afternoon, Boeing is slated to launch its passenger spacecraft, the CST-100 Starliner, to the International Space Station for the second time without people on board. The mission, called OFT-2, is part of an elaborate dress rehearsal that will help pave the way for people to ride on the vehicle in the future.

Today’s mission is a critical milestone as Boeing works to certify the vehicle for human spaceflight. Boeing developed Starliner as part of NASA’s Commercial Crew Program, an initiative that tasked private companies with developing spacecraft capable of carrying NASA astronauts to and from the International Space Station. NASA’s other Commercial Crew provider, SpaceX, is already ferrying astronauts to the ISS on a regular basis. But having Boeing’s Starliner in the mix will give NASA what it likes to call “dissimilar redundancy” — two different transportation options in case one goes out of commission.

This is Boeing’s second attempt at the test flight after a previous effort in 2019. In the first attempt, a series of software issues and a communications blackout prevented the vehicle from getting into the proper orbit, and Boeing had to bring Starliner home early. Another planned launch last summer got scrubbed just hours before liftoff due to some sticky propellant valves. Now, after years of work to remedy these issues, Boeing is ready to try again.

What time does Starliner take off?

Takeoff is scheduled for 6:54PM ET out of Cape Canaveral Air Force Station in Florida.

Scheduled time: New York: 6:54PM / San Francisco: 3:54PM / London: 11:54PM / Berlin: 12:54AM / Moscow: 1:54AM / New Delhi: 4:24AM / Beijing: 6:54AM / Tokyo: 7:54AM / Melbourne: 8:54AM

How can I watch the flight?

NASA plans to livestream coverage of the flight on its dedicated channel NASA TV, which can be found on YouTube and NASA’s website. Coverage begins at 6PM ET.

What can I expect from the mission?

OFT-2 should follow the basic structure of a flight to the International Space Station as if people were riding on board. In the interest of realism, engineers have placed a mannequin called Rosie the Rocketeer (named as an homage to Rosie the Riveter) inside the Starliner capsule. The mannequin is outfitted in the same blue pressure suit that future Starliner passengers will wear and is surrounded by a suite of sensors that will collect data about the flight. This is actually Rosie’s second flight, as the mannequin also rode along for the original OFT mission back in 2019.

“We’re also very, very jealous because this is human spaceflight, and Rosie the mannequin is the one that gets to take the trip instead of us,” said NASA astronaut Barry “Butch” Wilmore, one of the future flyers of Starliner, during a press conference.

Image: Boeing

Starliner takes off on top of an Atlas V rocket, manufactured and operated by the United Launch Alliance. After takeoff, the rocket will spend the next 15 minutes propelling the capsule to space. Following that initial ascent, Starliner will separate from the rocket. But its job won’t be done yet. At roughly 31 minutes following takeoff, Starliner will fire a series of four onboard thrusters to put itself into the right orbit needed for reaching the International Space Station. It was this maneuver that went awry back in 2019, so all eyes will be watching during this process.

Once Starliner achieves the planned orbit, the capsule will do a few demonstrations as it approaches the station on Friday, testing out sensors on the spacecraft and showing the spacecraft can halt on command as it gets closer to the ISS. But the biggest demonstration of all will come when Starliner attempts to dock with the International Space Station. Like SpaceX’s Crew Dragon, Starliner is equipped with an automatic docking system designed to autonomously maneuver the capsule onto an open docking port on the outside of the ISS.

Image: Boeing

The docking process is essential for Starliner’s mission, as it’s how future astronauts will actually reach the space station. Boeing also wasn’t able to demonstrate docking in its 2019 launch, and both the company and NASA are very keen on seeing it happen this time.

“Of course the whole mission is of interest to us, and we will learn, but the areas that we are most looking at because we haven’t exercised them yet are certainly the docking with the station,” Michelle Parker, Boeing vice president and deputy general manager of space and launch, said during a press conference.

Docking is currently scheduled to take place on Friday, May 20th at 7:10PM ET, with NASA coverage beginning at 3PM ET. The crew already on board the ISS will monitor the capsule’s approach. Once Starliner is attached, they’ll open the hatch to the vehicle on Saturday, May 21st, which is scheduled for 11:45AM ET. The astronauts will retrieve some cargo packed inside Starliner and put additional cargo back inside to be returned to Earth.

Starliner will camp out on the ISS for four to five days before it undocks and begins its journey home. Starliner will fly around the station while backing itself away from the ISS and position itself in a specific point above the Pacific Ocean. Then the craft will fire its thrusters again, taking itself out of orbit and putting itself on course toward the surface. Unlike SpaceX’s Crew Dragon, Starliner is designed to land on solid ground using a combination of parachutes and airbags to cushion its touchdown. Boeing has five different locations in the US where Starliner could potentially touch down, including White Sands Missile Range in New Mexico and the Dugway Proving Ground in Utah.

Starliner’s future astronauts include Wilmore, Mike Fincke, and Sunita Williams, all of whom will be watching the various milestones of the missions from Boeing mission control and other areas here on Earth. Depending on how this test flight goes, NASA may soon finalize the crew for Starliner’s first crewed test flight, called CFT.

But for now, the focus is on OFT-2. “We wouldn’t be here right now if we weren’t confident — confident — that this would be a successful mission,” Wilmore said.