NASA is now looking to inspect the Russian Zvezda module on the ISS. A leak in the module's aft section was detected last month, forcing NASA to undertake urgent repairs and an extra measure of scrutiny of all the spacecraft's systems before sending up new astronauts.

The launch window remains open but not for long
Although the Falcon 9 rocket and its Dragon capsule remain on track to take the four-person crew, no time was set for launching. The new tentative date is June 22, but further postponements are likely pending safety evaluations.

The Ax-4 crew has spent nearly three weeks in pre-mission quarantine as standard spaceflight practice. The agency announced the mission is still "go" to launch before the end of next month, pending the completion of ISS evaluations to ensure conditions are safe.