When SpaceX launches its 15th resupply mission to the International Space Station, possibly as early as Friday morning at 5:42am ET (09:42 UTC), the company plans to fly the Block 4 version of its Falcon 9 rocket for the final time.
The company’s next two launches in July were already known to be flying on the latest and presumably final revision to the Falcon 9 rocket—the Block 5 variant. But during a news conference Thursday, the company’s manager for the Dragon spacecraft program, Jessica Jensen, confirmed that there will be no more Block 4 flights after the impending space station launch.
The Block 5 version of the rocket, which has been optimized for reusability, has flown one time when it made a successful flight in May. Since then, SpaceX has been working through its inventory of previously flown rockets. The booster scheduled to fly Friday first launched just a little more than two months ago, on April 18, sending NASA’s planet-hunting TESS spacecraft into a lunar resonant orbit. This 10-week turnaround was remarkably fast for a Block 4 booster, but SpaceX says its Block 5 should be able to fly much more rapidly.