Falcon 9 | Axiom Mission 4 Axiom Space was planning to return crew to the International Space Station (ISS) this week on Axiom Mission 4 (Ax-4). The launch had been indefinitely delayed by SpaceX, however, following the discovery on Tuesday evening of a liquid oxygen leak in the engine bay of the first stage following a brief 7-second static fire test. A leak had been previously detected following Booster B1094’s maiden flight and was believed to have been addressed during refurbishment. NASA has subsequently reported that the mission will be postponed while it works with Roscosmos to investigate a new leak that has been discovered on the Zvezda service module of the ISS. This will be the seventh private Dragon mission and the 18th crewed launch for SpaceX. A revised launch date and time are yet to be announced – the flight will liftoff from historic Launch Complex 39A (LC-39A) at Kennedy Space Center in Florida. Peggy Whitson, former NASA astronaut and director of human spaceflight at Axiom Space, is commanding the mission — her second commercial human spaceflight, having flown on the Axiom Mission 2 (Ax-2) mission a little over two years ago. Joining her are Indian Space Research Organisation (ISRO) astronaut Shubhanshu Shukla, serving as pilot, and two mission specialists: European Space Agency (ESA) astronauts Sławosz Uznański-Wiśniewski of Poland and Tibor Kapu of Hungary. The Ax-4 crew in the Crew Dragon C213 capsule. (Credit: SpaceX) This mission will serve as Crew Dragon C213’s maiden flight, during which it is expected to be named by the crew. SpaceX has indicated this will be the last Crew Dragon capsule to be manufactured. Dragon will remain docked at the ISS for up to 14 days while the crew conducts 60 scientific studies and activities for multiple countries around the world. These experiments heavily focus on human health, plant and microbial biology, and the effects of microgravity, and include technology demonstrations from Axiom Space, ISRO, and ESA. Upon the completion of the mission, Dragon will splash down off the coast of California and will be recovered by one of SpaceX’s recovery ships. Booster B1094 is due to launch this mission on its second flight, having carried Starlink Group 12-10 to orbit just 42 days before the intended June 11 launch date. B1094 is expected to perform a return-to-launch-site landing shortly after liftoff, touching down on the concrete pad at Landing Zone 1 (LZ-1). Peggy Whitson already holds the record for the longest cumulative time in space by an American astronaut, which will grow with this mission. The flight features several additional milestones: Shubhanshu Shukla will become India’s second astronaut to reach space since 1984; Sławosz Uznański will become the second Polish astronaut to reach space since 1978; and Tibor Kapu will become Hungary’s second astronaut to reach space since 1980. The mission is also expected to set the record for the most research activities conducted during an Axiom Space mission to date. Electron launches a Gen-3 satellite for BlackSky on June 3. (Credit: Rocket Lab)