Earlier this month, SpaceX, Elon Musk's space exploration company that (he hopes) will one day take humans to Mars, suffered a setback. A Falcon 9 rocket was carrying a top-secret government payload that was meant to go into orbit. But according to multiple reports the payload was lost instead. 

No one involved is offering much information. The U.S. government, SpaceX, and Northrop Grumman, which built the mysterious payload and hired SpaceX to take it to space all cite the classified nature of the mission and have declined to provide any details. Here's what little we know:

1. The payload--whatever it was--was a very big loss.

The payload was code-named Zuma and none of the companies involved will say what it was. In fact, it was so top-secret that the feds won't even say which government agency or agencies were paying for it and using it. But according to an Ars Technica report, the Zuma payload was "hugely valuable," possibly worth $1 billion or more. And Elon Musk reportedly told SpaceX employees that it was the most important payload the company had ever launched.

2. SpaceX says it isn't to blame.

Even though it isn't sharing any information about what the rocket was carrying or for whom, or what went wrong, or indeed that anything did go wrong, there's one thing SpaceX wants the world to know: Whatever did happen wasn't SpaceX's fault. "Since the data reviewed so far indicates no design, operational or other changes are needed, we do not anticipate any impact on the upcoming launch schedule," according to a statement by president and COO Gwynne Shotwell.

It's bad timing for SpaceX, which is competing for lucrative government satellite launches, and constantly fighting to be taken seriously in a world dominated by old-line behemoths such as Northrop Grumman. Meantime, an insider source told Ars Technica that SpaceX and Northrop Grumman are each trying to blame the other for the incident.

With such limited information, it's impossible to know for sure, but preliminary reports point to a malfunction in the system that connected the payload to the Falcon 9 rocket, and should have released it into orbit before the rocket's upper stage fell back toward Earth. If so, it seems likely that Northrop Grumman built that system which suggests that SpaceX is indeed blameless.

3. There will be an investigation. 

With a billion dollar's worth of taxpayers' property in pieces at the bottom of the ocean, you can be quite certain there will be a thorough Congressional investigation, likely conducted in secret, with the results reported only to classified committees and the president. 

Will we ever know more about what the SpaceX rocket was carrying and what actually went wrong? Well, maybe. The report or reports that come out of the investigation will likely be classified and delivered only to those with appropriate clearance. But these things have a way of getting leaked.