The cause and the fix

After last year's pad explosion, SpaceX recovered some helium COPVs that weren't part of the accident. The tanks' inner aluminum liner was buckled in places, leaving gaps between the liner and carbon fiber overwrap. SpaceX did not speculate on why the liner buckled.

"Thermal issues seem to be a part of it," Lindy said, noting she could only draw on publicly available information. "The aluminum may have shrunk more than expected relative to the carbon overwrap. Its CTE (coefficient of thermal expansion) is much lower than aluminum. I mean, it's not even in the same ballpark."

According to SpaceX, supercool liquid oxygen may have seeped into the gaps that formed between the two liners. Helium doesn't liquify until -269 degrees Celsius—just four degrees warmer than absolute zero. That means the gaseous helium inside the COPV could have chilled the liquid oxygen trapped in the liner gaps even further—enough to solidify it, which occurs at -219 degrees Celsius.

At that point, SpaceX believes either friction or the snapping of a carbon fiber strand near the gap started the explosion that destroyed the rocket. Lindy told me she thought the explanation was credible—it doesn't take much to start a catastrophic conflagration in a liquid oxygen environment. And SpaceX said tests showed the colder the oxygen, the more likely this scenario was to occur.

"I think the general concept is feasible," she said. "The explanation, for me, is a bit simplistic, but an engineer is always going to say that."

SpaceX says they'll be using warmer helium from now on, in a "prior flight proven configuration based on operations used in over 700 successful COPV loads." (The company did not say when—or why—the configuration was changed out of the prior flight proven configuration.)

In the long run, SpaceX plans to fix the buckling issue altogether, though Lindy said this could be challenging.

"COPVs are a bit on the delicate flower side, is how I put it," she said. "Their care and feeding is not simple."

Risk versus reward

SpaceX is a private company backed by a billionaire and other investors. It succeeds precisely because it pushes the boundaries of rocket science. In the process, it has placed the entire launch industry on notice: Innovate and lower costs, or risk getting left behind.

When SpaceX sacrifices a rocket in the process, it has to answer to a much smaller group of stakeholders than organizations like NASA (which answers to American taxpayers) or United Launch Alliance (which answers to its parent companies, publicly traded Boeing and Lockheed Martin, both of which have wider aerospace interests).

By the time SpaceX starts shipping astronauts to the International Space Station, the company says it will have finished making major design changes to the Falcon 9. That's good news for astronauts that will entrust their lives to the launch vehicle. And even if an accident does occur, it would hardly be unprecedented; NASA lost 14 people in two space shuttle accidents because of bad bureaucratic choices.

In NASA's case, reminders of the two accidents are prominently posted at the agency's human spaceflight facilities. Placards at the Michoud Assembly Facility and Kennedy Space Center Vehicle Assembly Building remind workers that lives are literally on the line when rockets are being assembled and stacked.

Right now, only profit is at risk when SpaceX bolts a vehicle together. But that will soon change. When it does, will SpaceX's risk-reward equation look any different?