CAPE CANAVERAL, Fla, — At a media teleconference before the first flight of the Block 5 Falcon 9 rocket, SpaceX CEO and lead designer Elon Musk outlined some of the various upgrades to the Falcon 9 on the Block 5 version and revealed that, sometime next year, the company plans to launch, recover, re-fuel and re-launch a rocket within 24 hours.
Six years ago, SpaceX published an animation illustrating a reusable launch system, featuring powered decent and recovery of the first stage, second stage, and finally the Dragon space capsule. SpaceX made its first successful landing of a Falcon 9 first stage in December 2015. Several month’s later, in April 2016, the company successfully landed on a drone ship out at sea.
Over the course of the last 2.5 years, the company landed first stage boosters some 24 times. Many of those cores were re-flown—once. But the Block 5 is expected to enable the company’s goal of a rapidly reusable vehicle.
“The key to Block 5 is that it’s designed to do 10 or more flights with no refurbishment between each flight—or at least not scheduled refurbishment between each flight,” Musk said during the May 10, 2018, conference call. “The only thing that needs to change is you reload propellant and fly again.”
On May 11, 2018, the first Falcon 9 Block 5 version successfully launched the Bangabandhu-1 communications satellite into geostationary transfer orbit from Kennedy Space Center’s Launch Complex 39A. Some eight minutes later, the first stage of that vehicle landed on a drone ship several hundred miles downrange, completing the 25th recovery of a first stage. Once back at Port Canaveral, SpaceX began the long process of tearing the vehicle apart to ensure that the vehicle survived nearly unscathed as designed.
“Ironically, we need to take it apart to confirm that it does not need to be taken apart,” Musk said. “So this rocket probably won’t re-fly for probably a couple of months.”
Musk listed the major revisions to the existing Block 4 design, all of which together is expected to allow the “rapid reusability” first envisioned back in 2011. They include, but aren’t limited to:
- Merlin engine thrust increased by approximately 8 percent to 190,000 pounds at sea level
- Use of new hydrophobic thermal protection technology for the black interstage, the raceways, and the landing legs
- Much higher uplift strength and thermal protection of the aluminum “octaweb”—the load-bearing structure at the base of the nine Merlin engines
- A revised landing leg design that features internal latch mechanisms that can be opened and closed repeatedly with ease
- A revised base heat shield now constructed with high-temperature titanium.
- Upgradable avionics, upgraded flight computer and engine controllers, a more advanced inertial measurement system, higher fault tolerance, and elimination of the avionics tower
- Fully recoverable fairings (each one cost $6 million to build)
If the upgrades are demonstrated to truly allow for rapid reusability of the first stage, Musk said the vehicle should be able to fly 10 times with no scheduled maintenance. With some maintenance after 10 flights, he said SpaceX believes the Block 5 is capable of at least 100 flights before being retired.
“Our goal, just to give you a sense of how reusable we think the design can be, we intend to demonstrate two orbital launches of the same Block 5 vehicle within 24 hours, no later than next year,” Musk said. ” Because there’s only so much work you could even do in one day and a bunch of it consists of transporting the rocket from its landing site back to the launch site, mounting a new satellite on the rocket and loading propellant and going – and doing all of that within 24 hour period, while maintaining a very high level of mission assurance, is extraordinarily difficult. I think that will be a very exciting outcome.
Musk said that reusing the second stage of the rocket is still in the cards for the Falcon 9. For upcoming flights, he said the company is gathering data about the reentry experience of the stage.
“Previously we’ve not put a lot of effort into gathering data on the upper stage after it does its disposal burn,” Musk said. “So we’re required to do a disposal burn and kind of the stage re-enter and break up in an unpopulated area in the Pacific.
SpaceX, Musk said, wants to learn in detail at what altitude and speed the second stage breaks up and under what conditions. But it will need to transmit that data, which he said is tricky.
“When it’s coming in, it’s coming like a meteor,” Musk said. “So it’s got this sort of like, ball of plasma, and you can actually only broadcast sort of like, diagonally backwards. So we’ll be looking to communicate with, probably the Iridium constellation, and try to transmit basic data about temperature, state and health of the stage, loss in altitude. And then gradually, over the course of this year, we’ll be adding more and more thermal protection to the upper stage, and try to see what’s the least amount of mass necessary to return the upper stage in a condition that is reusable.”
Musk said he is confident SpaceX will be able to attain full reusability on the upper stage.
“The question is simply what the mass count is,” Musk said. “And we obviously will not take any action that creates risk for the ascent phase of the rocket and that puts the spacecraft in jeopardy.”
The more of Falcon 9 the company is able to recover and rapidly re-fly, the more the cost-savings add up. Musk said during the conference call that the first stage is some 60 percent of the total cost of the whole booster. The second stage is about 20 percent, the fairings are about 20 percent and launch costs are about 10 percent. Altogether, the rocket grade kerosene and liquid oxygen propellants account for some $300,000 to $400,000 per launch, he said.
“So if we’re able to reduce the cost of operation—fixed costs and whatnot, we can bring the marginal costs of Falcon 9 down under $5-6 million,” Musk said. “That would be really exciting.”
Musk and SpaceX have said that the Block 5 would likely be the final major version of the Falcon 9 before it is replaced by the company’s next-generation rocket, currently called the Big Falcon Rocket, or BFR. But there would still probably be minor changes to the Falcon 9 before the BFR’s introduction.
“I think it’s important to appreciate the fundamental motivations that I have, and I think that the team at SpaceX has, which is that we really want SpaceX to be a forcing function for improving, dramatically improving space technology to the point that it enables humanity to become a multi-planet species,” Musk said. “From our standpoint it was really critical to keep advancing rocket technology and achieve full and rapid reusability, in the absence of which spaceflight would always be far too expensive.”
If aircraft were not reusable, Musk said, a new plane would be needed for every flight. As such, ticket costs would be in the millions of dollars—one way—resulting in almost nobody being able to afford to fly.
“That’s the situation with expendable rockets today,” Musk said. “And what happens once you achieve reusability? Then tickets can go from a million dollars, to a few thousand dollars, or a few hundred dollars for short trips. And then fundamentally spaceflight will be open to almost anyone, just as air flight is.”
