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.
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.
Indeed, SpaceX intends to fly each Block 5 first stage it builds a minimum of 10 times, which would be hugely significant, as SpaceX has thus far only ever reused each of its Falcon 9 rockets a single time. Additionally, the company hopes to reduce the turnaround time between launches of a Falcon 9 booster, now several months, to a matter of weeks, or less.
Because SpaceX has no plans to fly Friday’s booster again, it will be expended into the ocean. However, the rocket’s second stage will make a much longer “coast” in space before de-orbiting after four revolutions around Earth. This is likely another test of the second-stage engine’s ability to fire after a longer period of dormancy in space.
During Thursday’s news conference, Jensen said SpaceX was still working an issue with a thermal panel on the Dragon spacecraft. This could delay the launch, but she said employees were proceeding for now as if the launch will go ahead on Friday morning.