Washington, June 1 : Mission officials at NASA and Boeing said they have detected "emerging issues" on Starliner before its first crewed flight slated in July, according to a new update. The mission, called Crew Flight Test (CFT), will launch NASA astronauts Butch Wilmore and Suni Williams to the International Space Station (ISS) aboard Boeing's Starliner capsule no earlier than July 21. During a "checkpoint review" conducted last week, the mission officials identified a few "emerging issues that need a path to closure" to resolve before taking that big step, NASA said. "We are taking a methodical approach to the first crewed flight of Starliner incorporating all of the lessons learned from the various in-depth testing campaigns, including Starliner's flight tests and the agency's verification efforts," said Steve Stich, manager of NASA's Commercial Crew Programme, in a statement. "All Orbital Flight Test-2 anomalies are closed. In addition to the closeout of ongoing work, the team remains vigilant on tracking new technical issues as we complete certification for crewed flight," he added. The officials said about 95 per cent of the Crew Flight Test certification products are complete. This includes approval of Starliner's crew module batteries, based on additional testing and analysis, along with post-certification flight mitigations and a proposed battery upgrade for future missions. In addition, the Starliner team is replacing the valve that was restricting flow to one of two redundant loops, and running a diagnostic to confirm the suspected issue with the malfunctioning hardware. NASA and Boeing also are working to reassess Starliner's parachute system margins based on new data reviews as part of the ongoing design certification process. Engineers are reviewing the overall efficiency of certain joints within the parachute system to confirm they meet all required factors of safety for crewed flight. "Crew safety remains the highest priority for NASA and its industry providers, and emerging issues are not uncommon in human spaceflight especially during development," Stich said. Starliner spacecraft fueling is expected to begin as early as mid-June, and there is some operational flexibility in that timeline that can be used if needed. Teams will continue to monitor the forward work and determine whether an adjustment in the current launch date is needed. An update on the team's progress will be provided in the coming weeks, the officials said. /IANS