In 2002 when Elon Musk revealed his idea of making rocket flights comparable to air travel many folks in and outside of the aerospace industry thought he was more than a bit looney.
Fast forward. On May 11 SpaceX successfully launched its most modern Falcon 9 rocket delivering the first Bangladeshi telecom satellite into orbit. The first stage booster landed approximately 11 minutes after liftoff on a drone ship floating 340 nautical miles down range of Cape Canaveral in the Atlantic Ocean. It was the 25th successful landing of a booster rocket by the Hawthorne, Calif. company.
The enhanced version of Falcon 9 is called Block 5. Musk sees a host of new milestones for SpaceX, including launching and landing the same rocket twice in 24 hours – as early as next year.
"We expect [Block 5] to be the mainstay of SpaceX business," Musk said in a teleconference with space reporters a day before the launch. “We still need to demonstrate it. It’s not like we’ve done it. But it can be done.”
After eight years of flying the Falcon 9 rocket, SpaceX has absorbed thousands of lessons learned from 51 flights and engineered them into this new booster. Nearly twice as powerful as the Falcon 9 rocket in 2010, Musk called Block 5 "the last version" of the orbital class rocket.
The Block 5 features a series of upgrades that should significantly boost its reusability. Where the first stages of previous Falcon 9 iterations have launched a maximum of two times, the Block 5 first stage will be capable of 10 orbital flights with just inspections between liftoff and landing, and perhaps 100 or more with some refurbishment involved according to SpaceX.
The final design of Falcon 9 Block 5 features modifications for simpler manufacturing that will enable SpaceX to meet NASA commercial crew requirements, and to include Air Force requests. Musk said the company will spend a few months disassembling and inspecting this first Block 5 booster before reuse.
“Ironically, we need to take it apart to confirm that it does not need to be taken apart,” said Musk, SpaceX's chief executive officer and lead designer. “This rocket probably won’t re-fly for probably a couple of months. But by late this year we should be seeing substantial reflight of Block 5 vehicles, probably with Block 5 boosters seeing their third, maybe their fourth reflight.”
Designed to be the most reliable rocket ever built, Musk acknowledged feeling stressed about the Block 5's first mission, yet very confident in the vehicle's long-term prospects.
"You know, it could be a thousand things that go right on this rocket, and one that goes wrong, and a passing grade for rockets — the reason that it's so hard to make an orbital rocket work — is that your passing grade is 100 percent," Musk explained. "And you can't fully and properly test an orbital rocket until it launches, because you can't recreate those exact conditions on Earth. Everything's sort of a proxy for traveling hypersonically through a vacuum. Yeah. Man. Anyway, I'm stressed."
“For those that know rockets, this is a ridiculously hard thing. It has taken us since, man, since 2002. Sixteen years of extreme effort and many, many iterations, and thousands of small but important development changes to get to where we think this is even possible.”
In true Musk hyperbole, he added, “Crazy hard.”
Among the most extensive changes to the new booster is a strengthening of the “Octaweb,” essentially the engine bay that carries the load of the Falcon 9’s nine rocket engines and insulates them from one another in case an engine fails on ascent. By using 7000 series aluminum (instead of 2000 series), the Octaweb has a “much stronger” structure, Musk said, and it also has additional thermal protection.
The new Falcon 9's landing legs are now retractable, allowing ground crews on both coasts to easily reset them instead of removing them between launches. Block 5 also sports SpaceX's titanium grid fins, which have guided SpaceX boosters back to landings only a few times, including the twin-booster touchdown of Falcon Heavy. The bear-trap-shaped fins are a permanent feature on Block 5, providing increased control and aerodynamics.
The Merlin engines' power have been boosted by about 8 percent at sea level, now boasting 190,000 pounds of thrust at liftoff. According to Musk, SpaceX will ultimately build about 30 to 50 Block 5 rockets. The final number depends on how many customers want to fly on a “new” booster, and how many will prefer a “flight proven” version. Over time, he expects the aerospace industry’s preference for used boosters to increase as the technology proves itself.
Musk is doubling down on his assertion that the new Falcon 9 will have full reusability. In recent launches SpaceX has attempted to recover the $6 million payload fairing that splits into two after the launch of the Falcon 9 rocket and returns to the ocean. SpaceX also continues to study the feasibility of returning and reusing the second stage of the Falcon 9, and Musk said he’s confident it can be done.
What's the rocket’s overall cost? The first stage accounts for 60 percent, the upper stage 20 percent, the fairing 10 percent. The remainder are costs associated with the launch itself such as the fuel costs that Musk pegs at between $300,000 and $500,000. Current launch costs are roughly $62 million which Musk expects to dramatically lower over time.
Musk projects this final version of the Falcon 9 will probably fly about 300 missions over its lifetime. Then it will be time to unveil the Big Falcon Rocket (BFR) which is currently being designed to take people to Mars. Las week's mission was SpaceX’s ninth of the year in less than five months, putting the company on pace to double last year’s 18-launch total and launch more often than any other nation, Musk said.
"It was really critical to keep adapting rocket technology and achieve full and rapid reusability, in the absence of which spaceflight would always be far too expensive," he said. "And then fundamentally, spaceflight will be open to almost anyone, just as air flight is. So that’s why we did all this."