Tonight, SpaceX is scheduled to launch its 18th and final mission of the year, sending 10 satellites into orbit for longtime customer Iridium. The company is using another one of its used Falcon 9 rockets for this flight, which will launch out of Vandenberg Air Force Base in California. But this time, the vehicle will not be landing; its landing legs appear to have been removed, and the rocket will fall to Earth after the launch is over.
It’s unclear exactly why this rocket won’t be landing for this mission. SpaceX has easily landed rockets following three previous Iridium missions, which have had nearly identical profiles to this one. In a statement to the The Verge, SpaceX said that the decision to land rockets are made on a “case by case” basis “and are based on mission requirements and the needs of our manifest.” However, Iridium’s CEO, Matt Desch, tweeted that the weight of the satellites don’t preclude a landing.
It’s possible that SpaceX does not want to recover this particular rocket since it’s an older iteration of the Falcon 9. Tonight’s booster is a version known as Block 3, and it first flew during another mission for Iridium in June of this year. However, the company is hoping to soon move on to a final, upgraded version of the vehicle called the Block 5, and CEO Elon Musk has said that the Block 5 will improve both the performance and reusability of the Falcon 9 in the future.
The company still boasts an impressive landing record this year, though. SpaceX successfully landed every Falcon 9 it attempted to recover in 2017, making 14 landings in total, and overall, the company has landed 20 of its Falcon 9 rockets since December of 2015. And with tonight’s launch, SpaceX will have flown five used rockets this year. All of those re-flights have landed a second time, though, so this will be the first previously flown Falcon 9 that won’t land again.
This is SpaceX’s fourth flight for Iridium. The company has a contract to launch 75 satellites total as part of the new Iridium NEXT constellation, which will provide communications services over land and sea in regions all over the world. SpaceX has sent up 30 Iridium NEXT satellites so far, and when these satellites deploy, there will be 40 total in lower Earth orbit.
Take off is scheduled for 8:27PM ET, and SpaceX has an instantaneous launch window for this mission, meaning the Falcon 9 has to go up exactly on time or move to a different day. The company has a backup launch opportunity on Saturday at 8:21PM ET. SpaceX’s coverage of the launch will begin around 15 minutes prior to lift off. Check back then to watch the final Falcon 9 of 2017 get off the ground.