Four months after a SpaceX rocket exploded on its launch pad in Florida, the pioneering, privately owned space company is ready to return to space.


If all goes well Sunday, we could soon see SpaceX resume regularly tweeting out images like this one -- of rockets making sonic booms, instead of rockets simply going "boom." Image source: SpaceX.

That's the short version of SpaceX's latest "anomaly update," posted on its website on Monday. After four months investigating an accident that Elon Musk called "the most difficult and complex failure we have ever had in 14 years," SpaceX is more or less convinced it's figured out (1) what went wrong, and (2) how to prevent it from going wrong again, and is now ready to launch again -- tomorrow.

Now here's the long version:

What went wrong

Within the second stage of SpaceX's Falcon 9 rocket are a series of three aluminum vessels containing super-chilled liquid helium inside a main tank that holds the rocket's liquid oxygen for combustion. The purpose of these vessels is to release helium to replace oxygen from the fuel tank as it is consumed, maintaining pressure within the fuel tank.

Each of these three vessels is shrink-wrapped with carbon composite on the outside. The problem is, this "wrap" sometimes develops tiny wrinkles between it and the aluminum lining, into which oxygen can seep and pool.

SpaceX believes that its anomaly was caused by the helium in the vessels being pumped in too cold, freezing oxygen trapped in one of these pools and turning the oxygen into a solid. This solid oxygen then somehow reacted with the composite exterior -- either by expanding and bursting the composite wrap, or perhaps igniting a spark through friction -- puncturing the vessel and igniting the fireball.

Now, there were no cameras within the Falcon 9 to observe the explosion as it happened, and the entire process took only 93 milliseconds start to finish, which makes it difficult for SpaceX to know exactly how the failure took place. But SpaceX has narrowed down its analysis to the point where the company is all but certain that something like what has been described above is what actually happened. Furthermore, SpaceX is sufficiently sure of this that it believes if it can prevent its oxygen from freezing again it can prevent another explosion from occurring in future launches.

How to fix it

SpaceX has two plans for preventing such anomalies from occurring in the future. Near-term, the fix involves pumping helium into the fuel tank vessels at warmer temperatures to prevent the helium from freezing oxygen trapped in any wrinkles in the overwrap.

Longer term, SpaceX will implement manufacturing changes to prevent wrinkles from occurring in the first place. That should eliminate the possibility of oxygen pools forming -- and permit SpaceX to resume loading helium at lower temperatures, accelerating the fueling process.

What comes next

SpaceX hasn't said how long it will take to implement its long-term fix. The short-term fix, on the other hand, can be implemented immediately. In fact, if all goes well, we should see it implemented in the Sunday launch of 10 Iridium (IRDM -0.28%) NEXT communications satellites departing Vandenberg Air Force Base in California.

What it means for investors

After several months' hiatus, SpaceX today is in a precarious state -- no longer profitable or cash-flow positive, and with a launch manifest brimming with impatient customers, some of which have already begun jumping ship to fly with SpaceX's competitors.

According to SpaceX, the company has 70 customers signed up to launch rockets, including 42 named missions on its manifest. Among other missions, SpaceX hopes this year to launch its Falcon Heavy lift rocket for the first time ever, to reuse a previously launched-and-recovered Falcon 9 (also for the first time ever), and maybe even to run an unmanned Crew Dragon test flight (yet another first).

In addition to the headline-making potential of such "first" missions, the faster SpaceX returns to business, the faster it can begin billing those customers -- at $62 million a pop and more. And the faster it can resume billing, the faster it will return its balance sheet to health.

And on the flip side? If SpaceX suffers another failure Sunday, or is forced to delay launch, the balance sheet will deteriorate further, Iridium's satellites will spend more time stuck on Earth where they cannot generate revenue for that company, and SpaceX's other customers will have more time to wonder:

Maybe next time we should just buy a rocket ride from United Launch Alliance instead?