The CST-100 Starliner, Boeing’s new passenger spacecraft, successfully docked with the International Space Station, indicating that the vehicle can transport humans to the ISS in the future. After years of delays and failures, Starliner has now confirmed this critical capability in space.

The Starliner is now undergoing a critical NASA test flight known as OFT-2 or Orbital Flight Test-2. Boeing designed the capsule for NASA’s Commercial Crew Program to transport humans to and from the International Space Station. However, before anyone boards, NASA has tasked Boeing with doing an uncrewed flight demonstration of the Starliner to demonstrate that the capsule can meet all of the main milestones it will need to meet while carrying passengers.

So far, Boeing has struggled to demonstrate the Starliner’s capabilities. This mission is known as OFT-2 since it is essentially a repeat of a mission that Boeing tried in 2019. Starliner launched to space as intended during that voyage, but a technical problem prevented the capsule from reaching the proper orbit to meet with the ISS. Boeing was forced to return the vehicle early, and the Starliner’s ability to dock with the ISS was never tested.

Starliner has finally demonstrated what it was meant to achieve, nearly two and a half years later

The capsule guided itself onto an open docking port on the space station using a set of sensors. During the webcast of the docking, Steve Siceloff, a Boeing communications representative, remarked, “Boeing Starliner spacecraft completes its historic first docking to the International Space Station, creating a new avenue of access for crews to the orbiting laboratory.” Docking was delayed by around an hour due to difficulties with the Starliner’s visuals and docking ring, which were rectified before the docking.

After Boeing revealed some concerns with the capsule’s thrusters yesterday, there was some concern regarding Starliner’s ability to connect with the space station. Starliner was launched into orbit at 6:54 p.m. ET, on an Atlas V rocket built and operated by United Launch Alliance. Starliner had to use its engines after separating from the Atlas V to get into the right orbit for reaching the space station. However, after the maneuver, Boeing and NASA announced that two of the 12 thrusters used by the Starliner for the process failed and were switched off prematurely. The capsule’s flight control system was able to kick in and reroute the thruster to a functional position, allowing Starliner to enter a stable orbit.

NASA and Boeing eventually declared that the problem would not affect the rest of the Starliner’s mission. After the trip, NASA’s program manager for the Commercial Crew Program, Steve Stich, remarked in a press conference, “There’s no need to resolve them.” “However, I know what the teams will do, and what we always do is go over the data and attempt to figure out what happened,” Boeing stated today that a dip in chamber pressure caused the thruster to cut off early, but that the system performed correctly throughout subsequent thruster burns. According to Boeing, the issue “does not represent a risk to the rest of the flight test” because the spacecraft has redundancies.

Boeing also revealed today that the Starliner crew is looking into some strange behavior from a “thermal cooling loop,” but that temperatures on the spacecraft are stable.

Starliner will now remain docked to the space station for the next four to five days. The astronauts already aboard the ISS will open the hatch to the vehicle tomorrow morning and retrieve some cargo that has been stored inside. A mannequin named Rosie the Rocketeer is also inside Starliner, modeling what it would be like for a human to ride inside the ship.

Starliner will disconnect from the ISS and move away from the station for its return home after a brief stay on the station. The capsule will use its engines to break free from orbit and return to Earth. The two thrusters that failed were the identical ones that were utilized in this deorbit operation, yet NASA and Boeing seemed unconcerned. “All we have to do now is see whether we can get the thrusters back,” Stich remarked. He also mentioned that the operational thrusters may be employed and that Boeing could use a new set of thrusters if necessary. “So the spacecraft has lots of redundancy.”

For now, the Starliner team is celebrating their big milestone. “Today marks a great milestone towards providing additional commercial access to low Earth orbit, sustaining the ISS, and enabling NASA’s goal of returning humans to the Moon and eventually to Mars,” NASA astronaut Bob Hines, currently onboard the space station, said after the docking. “Great accomplishments in human spaceflight are long remembered by history. Today will be no different.”