Posted on by Evan Gough

SpaceX Performs an Experimental High Retrothrust and Survives a Water Landing

SpaceX’s most recent rocket launch saw the Falcon 9 perform a high retro-thrust over water, with no drone ship in sight. SpaceX never intended to reuse this rocket, and they haven’t said exactly why.

This launch was conducted on January 31st, and the payload was a communications satellite called GovSat-1. It’s a public-private partnership, and GovSat-1 is a heavy satellite which was placed into a particularly high orbit. It will be used by the government of Luxembourg, and by a private European company called SES. It’ll provide secure communications and surveillance for the military, and it has anti-jamming features to help it resist attack.

A high orbit and a heavy payload means that the Falcon 9 that launched it might not have had enough fuel for its customary drone landing. But other Falcon 9s have launched payloads this high and landed on droneships for reuse. So what gives?

According to SpaceX, they never planned to land and reuse this one. They didn’t exactly say why they did it this way, but it’s been speculated that this one was an older iteration of the Falcon 9 known as the Block3. This is the second time SpaceX flew a Block 3 iteration without trying to reuse it. The first time they launched one without reusing it, it carried 10 Iridium satellites into low-Earth orbit.

The Falcon 9 is flying in Block 4 configuration now, with Block 5 coming in the near future. SpaceX says that the Falcon 9 Block 5 will improve the performance and the reusability of the rocket in the future. They’ve also stated that the Block 5 will be the final configuration. Maybe they let this one land in the ocean because it’s just not needed anymore.

SpaceX’s reusable rocketry technology is their primary development. The main booster of their Falcon 9 can be reconditioned and used again and again, keeping costs down. After lift-off, and after the primary stage is released, the main-stage booster lands on a SpaceX drone ship, where it is secured and delivered to shore to be reused.

In this case, SpaceX wanted to test a high retro-thrust landing. The test consisted of three separate burns performed over water, rather than on a drone ship, to avoid damaging the ship. The rocket itself wasn’t expected to survive, but did. Or it partly survived, anyway. As Elon Musk confirmed in his tweet:

The retro-thrust rockets on SpaceX rockets like the Falcon 9 allow the rocket to land softly. They thrust in the opposite direction the rocket is landing, and cushion the Falcon 9’s landing on the droneship.

With the successful static test of SpaceX’s Falcon Heavy last week, a first launch for the Heavy is in sight. Testing high retro-thrust landings could be related to the upcoming first launch, even though, as Elon Musk said, merely getting the Falcon Heavy off the pad and back would constitute a successful first flight. But that’s just a guess.

The Falcon Heavy is designed to be reusable, just like its little brother, the Falcon 9. Reusability is key to SpaceX and is the whole reason Musk started the company: to make spaceflight more affordable, and to help humanity travel beyond the Moon.

SpaceX plans to tow this Falcon 9 back to shore and see if it can be salvaged. But after being dunked in salt water, any meaningful salvage seems unlikely. Who knows. Maybe Elon Musk will use it for flame-thrower target practice.

But the fate of this single rocket isn’t really that important in the grand scheme of things. What’s important is that SpaceX is still testing designs, and still pushing the boundaries of lower-cost spaceflight.

With that in mind, here’s hoping the whiz kids at SpaceX can destroy a few more rockets. After all, it’s all in the name of science.