Nasa is set to attempt another launch of the Starliner astronaut capsule on Thursday.
The uncrewed test flight of the Boeing’s Crew Space Transportation (CST)-100 Starliner spacecraft comes after a series of delays, including a failed launch in 2019 when the capsule was not able to reach the International Space Station (ISS).
Nasa’s Boeing Orbital Flight Test-2 (OFT-2) – carrying no astronauts and only a test dummy – is another step on the path to regular human spaceflight to the ISS, Nasa has said.
It will test the changes and improvements made to Starliner, and prove the system is ready to fly astronauts.
If successful and following subsequent data reviews, Nasa and Boeing will set a target launch date for the Crew Flight Test (CFT) with astronauts on board.
Launching at just before midnight, Starliner is expected to arrive at the space station for docking about 24 hours later with more than 800 pounds of cargo, including about 500 pounds of Nasa cargo and crew supplies.
The mission will test the capsule’s capabilities from launch to docking, re-entry into Earth’s atmosphere and a desert landing.
It is hoped the test will provide valuable data that will help Nasa certify Boeing’s crew transportation system to carry astronauts to and from the space station.
While there will be no crew on board the test flight, the commander’s seat will be occupied by the test dummy, Rosie the Rocketeer.
She is equipped with 15 sensors to collect data on what astronauts will experience during flights on Starliner.
After a successful docking, Starliner will spend five to 10 days aboard the ISS before returning to Earth in the western United States.
It will return with nearly 600 pounds of cargo, including reusable Nitrogen Oxygen Recharge System tanks that provide breathable air to station crew members.
The test flight of the commercial crew spacecraft will take off on a United Launch Alliance Atlas V rocket at 11.54pm (BST) from Cape Canaveral Space Force Station in Florida.
The Commercial Crew Programme is part of Nasa’s efforts to help the private sector to develop and fly human space transportation systems.