Last year reusable rockets entered the mainstream, and there’s no going back - Ars Technica

• On December 13, 2020, a Falcon 9 rocket launched the Sirius XM-7 mission. It was the seventh flight for this first stage.

  Trevor Mahlmann

• This was the most experienced rocket to fly a commercial mission.

  Trevor Mahlmann

• Falcon 9 B1051 entering Port Canaveral aboard SpaceX's Just Read The Instructions droneship after its seventh successful launch and landing.

  Trevor Mahlmann

• Close-up of the Falcon 9 logo on B1051.7 after the Sirius XM-7 mission.

  Trevor Mahlmann

The notion of reusing rockets finally went mainstream in 2020. As the year progressed, it became clear that SpaceX launch customers have gotten a lot more comfortable with flying on used, or "flight-proven," first stages of the Falcon 9 rocket. One commercial customer, Sirius, launched its XM-7 satellite on the seventh flight of a Falcon 9 booster in December. Also, the first national security payload flew on a reused booster last month when the US National Reconnaissance Office launched its NROL-18 mission on the fifth flight of a Falcon 9 first stage.

NASA, too, agreed to fly future crewed missions to the International Space Station—beginning with the Crew-2 spaceflight in the spring of 2021—on used Falcon 9 rockets. And the US Space Force said it would launch its GPS III satellites on used boosters in the future as well. These are among the highest-value missions the United States has.

Another important step came when a second US launch company, Rocket Lab, began to demonstrate rocket reuse. The company experimented throughout 2020 on ways to protect the return of its Electron first stage during reentry into Earth's atmosphere. Then, it recovered an Electron stage for the first time in November.

"When we look back on 2020, we will say this year was a watershed moment," said Randy Kendall, vice president of launch and enterprise operations for The Aerospace Corporation, in an interview. "Commercial, civil, and national security missions have all signaled their intent to fly their most precious payloads on previously flown rockets."

A long time coming

NASA deserves credit for pioneering work in reusable spaceflight. The space shuttle was the world's first partially reusable launch system, with the orbiter and solid rocket boosters capable of multiple flights after substantial refurbishment. But it wasn't cheap—the best independent estimate of the shuttle's cost over the lifetime of the program is about $1.5 billion per launch.

In the 1990s, NASA then funded the Delta Clipper program to test vertical takeoff and vertical landing. Eventually, it would launch reusable DC-X vehicles 12 times from White Sands Missile Range in New Mexico, reaching a maximum altitude of 3km. The program was canceled in 1996 after an accident and due to a lack of funding.

With its Falcon 9 rocket, SpaceX carried forward the concept of vertically launching and landing a rocket. And from the shuttle, SpaceX learned that it was not enough to build a reusable rocket. A launch vehicle also had to be rapidly reusable, and at a lower cost. SpaceX is getting there, as it has cut turnaround times for the use of a Falcon 9 core to less than two months. And while the Falcon 9 is smaller and less capable than the shuttle, its per-mission cost is substantially than $50 million, or 3 percent of a shuttle flight.

"People who have been in this industry for awhile have been looking at this, and hoping for awhile it would happen, and then all of a sudden you have a tipping point," Kendall said. "There was no doubt the physics could be conquered, it was a question of whether the economics could be conquered. In the future, I think most companies will have some element reuse. Everyone I’ve talked to is thinking about it. The Europeans, Chinese, and Russians all have plans for reuse within the next decade."

Falcon 9

It has now been five years since SpaceX successfully landed a Falcon 9 rocket in December 2015. Since then, the company has returned about 70 additional rockets and re-flown a booster 49 times. During the same time period, SpaceX's main competitor, United Launch Alliance, has flown its expendable Atlas V rocket 26 times.

"We have flown more flight proven boosters than Atlas has flown in the last five years," said Gwynne Shotwell, president and chief operating officer of SpaceX. As recycled Falcon 9 first stages have flown often and completed their primary missions with 100 percent success, SpaceX customers and their insurers have gained confidence in the vehicle.

"We're demonstrating what we're demonstrating," Shotwell said. "On the commercial side, the insurance community responded appropriately to it. There's not a premium that needs to get paid for flight proven. I remember doing the first briefing to the underwriter saying, 'Look, you guys are going to want people to fly flight proven. You're going to see that it's easier to get off the deck when you've already flown that rocket. You wring out the issues on the first flight.'"

By investing in reuse, SpaceX has not only been able to significantly cut its cost per launch, it has also freed up a lot of factory space at its main factory in Hawthorne, California, because it no longer has to build nine new Merlin engines and a first stage core for each flight.

"It's great that we didn't have to get to 40 cores in a year with Falcon 9, because we were trying to figure out layout of factory to do that," Shotwell said. "And booster production obviously takes a ton of floor space. Not having to build 40 boosters in a year is super helpful to the company's ability to flex and do work on other projects, there's no question about it. We moved some Falcon folks into Dragon. We're moving some Falcon and Dragon folks into Starship, of course."

Electron

Rocket Lab is seeking to increase its production capabilities with reuse, too. By reusing a first stage once, Rocket Lab cofounder Peter Beck said the company could double his production capability and catch up to customer demand.

Beck said he was originally skeptical about reuse, especially for smaller orbital rockets. When Rocket Lab first began developing its Electron rocket nearly a decade ago, SpaceX had not yet successfully landed a Falcon 9 rocket. In fact, when SpaceX built its first rocket, the smaller Falcon 1—only a little bit bigger than Electron—the company had tried to reuse it. For each mission, a parachute was supposed to extend from the first stage. But SpaceX never came close to successfully fishing an intact Falcon 1 first stage out of the ocean.

Only in 2017 and 2018, as Electron began flying and Beck studied flight data, did he come to believe his rocket could be safely brought back to Earth. Now, having completed some preliminary tests and planning more recoveries in 2021, Beck has become a convert.

"If Rocket Lab ever builds a new vehicle, it will fundamentally be reusable from day one," he said. "I’m really surprised when I see new vehicles in development now that aren’t reusable."

Listing image by Trevor Mahlmann

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