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SpaceX Faces the Hard Truth about Soft Landings—They’re Tough to Do

With two partially successful landing attempts of its Falcon 9 booster, the private company inches closer to its goal of making a fully reusable rocket

 

After launching a payload into space from Cape Canaveral, Fla. this afternoon, a SpaceX Falcon 9 rocket almost landed in the history books when its first stage hit a bull's-eye, vertically landing on a robotic barge in the Atlantic Ocean. The trouble was, the booster hit the bull's-eye too hard, according to tweets from SpaceX CEO Elon Musk shortly after the launch.

 

   

The company had been hoping for a softer vertical landing so that the Falcon 9 booster could be refurbished and reused, a strategy that Musk has said could reduce launch costs “by as much as a factor of a hundred.” Despite such landings being a longtime staple of science fiction, to date no rocket has ever managed the feat. SpaceX's previous attempt, in January of this year, also ended in a Falcon 9 booster crashing into its barge.


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The launch’s primary purpose was not to test rocket recycling but rather to send the company’s Dragon capsule to the International Space Station. The launch was the sixth of twelve such resupply missions SpaceX is sending to the space station as part of a $1.6-billion contract with NASA. Packed with nearly 2,000 kilograms of supplies and science experiments, the Dragon capsule flawlessly separated from the Falcon 9's second stage and deployed its power-supplying solar panels. It should dock with the station on Friday, and is slated to return to Earth some five weeks from now carrying trash and other discarded items from the station.

There are obvious reasons to develop reusable rockets. Right now the reigning paradigm is to throw away most or all of a launch vehicle after using it only once, something that aerospace experts occasionally equate to tossing a jetliner in the scrapyard after a single flight. Make a rocket reusable and you can fly it again and again, like an airplane, potentially making space travel as affordable and routine as a transcontinental flight. With easier access to space assured Earth’s economic sphere could then expand into the rest of the solar system, bringing about a new golden era in human history. At least, that is the theory held by generations of space age dreamers. But in practice, despite decades of concerted effort, to date no economically viable reusable space launch system has emerged—even NASA’s mostly reusable space shuttles proved too problematic to keep flying. SpaceX, like many companies before it, intends to change all that. And, despite its two less-than-stellar soft-landing attempts, it seems to have a better chance than any of its noble, failed predecessors.

Already, the company has close to fifty launches on its manifest, representing nearly $5 billion in contracts to launch commercial satellites, scientific spacecraft and space station resupply missions. The company intends to eventually return its rockets from space to their land-based launch sites rather than to ocean-based drone ships. It has partnered with Google to develop a global broadband Internet service reliant on hundreds of small satellites. It’s also developing a beefier rocket, the Falcon Heavy, as well as an upgraded human-rated Dragon capsule, which together could take astronauts on journeys to Earth orbit and beyond. Musk has said he wants to make humanity a multiplanetary species and intends to get out of the rocket-launch game when he retires on Mars. Developing reusable rockets is crucial to all this, but many experts say that even if and when SpaceX demonstrates a successful soft landings, it will still have a long way to go before its grand plans can be realized.

“Reusability has been the ‘holy grail’ for the space launch industry for decades” and was a primary motive for NASA’s space shuttle program, says John Logsdon, a space policy expert at George Washington University’s Space Policy Institute (SPI). But although the space shuttle orbiters and solid-fuel rocket boosters were reusable, refurbishing them required months of work by a small army of technicians, and the entire system’s costly complexity was a key factor in the catastrophic loss of two orbiters and their crews. Averaged over the lifetime of the space shuttle program each flight ended up costing about $1.5 billion—the same as NASA’s entire 12-flight contract with SpaceX. “The issue is not just reusability but reusability at low cost,” Logsdon says. “What SpaceX needs to do is demonstrate frequent reuse of the same Falcon 9 first stage without expensive servicing between uses. A successful landing is just an initial step.”

According to Leroy Chiao, an industry consultant and former NASA astronaut, in addition to demonstrating low refurbishment costs SpaceX must also show it can efficiently recover and recertify its rockets. “Eventually, SpaceX plans to fly the booster back to the launch site for recovery” rather than land them on barges, Chiao says. Once a rocket is recovered and refurbished, he adds, it must also be recertified for flight. “Like refurbishment, this must be set up correctly or the costs could be very high.” Consequently, until SpaceX has recovered, refurbished and recertified not one but numerous Falcon 9 boosters no one will really know how cost-effective its quest for reusability can be.
 
The company has already made great progress since its first soft-landing tests, when a Falcon 9 booster briefly hovered above the waves before plunging directly in the ocean. In January, during its first attempt to land on SpaceX’s “autonomous spaceport drone ship,” the booster lost control during its descent, coming in tilted askew and exploding on the barge in what SpaceX CEO Musk jokingly called a “rapid unscheduled disassembly.”



The company attributed that failure to the booster running out of hydraulic fluid for the “hypersonic grid fins” that stabilize it during landing. For today’s landing attempt, the company increased the booster’s reserves of hydraulic fluid and also repaired and revamped the barge to endure heavier seas and higher winds. Pending further investigation, the exact cause of the hard landing remains unknown, but this time the rocket approached the robotic barge upright, apparently only tipping over after touching down.
 
Although vital to progress, all of SpaceX's testing and tinkering could prove problematic for the company's short-term business prospects, says SPI Director Scott Pace. When the returning booster slammed into the SpaceX barge during the January attempt, that betrayed a problematic lack of an “abort mode” for landing a Falcon 9, he says. “If you know you are not in control of vehicle attitude—and they were not—then why try to land on the barge? That doesn’t help the rocket and hurts the barge.”
 
“I see SpaceX as engaging in a series of innovative experiments toward the goal of a reusable first stage,” Pace adds. “A major challenge created by innovative experiments is the impact on providing mission assurance. Changing the configuration with every launch makes it hard to feel confident in using the vehicle for high-value payloads…. Customers don’t care about reuse experiments—they just want to know that the attempt to do so won’t hurt the payload.”

SpaceX will try again to soft-land a Falcon 9 booster as soon as June 19 of this year, during the company's next cargo resupply flight to the International Space Station.

Lee Billings is a science journalist specializing in astronomy, physics, planetary science, and spaceflight, and is a senior editor at Scientific American. He is the author of a critically acclaimed book, Five Billion Years of Solitude: the Search for Life Among the Stars, which in 2014 won a Science Communication Award from the American Institute of Physics. In addition to his work for Scientific American, Billings's writing has appeared in the New York Times, the Wall Street Journal, the Boston Globe, Wired, New Scientist, Popular Science, and many other publications. A dynamic public speaker, Billings has given invited talks for NASA's Jet Propulsion Laboratory and Google, and has served as M.C. for events held by National Geographic, the Breakthrough Prize Foundation, Pioneer Works, and various other organizations.

Billings joined Scientific American in 2014, and previously worked as a staff editor at SEED magazine. He holds a B.A. in journalism from the University of Minnesota.

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