While all eyes are on SpaceX’s Falcon Heavy rocket, set to claim the title of most powerful rocket platform on the planet with its inaugural launch later this month, Elon Musk’s space faring company has another January launch slated… one he’d rather keep your eyes off of.

SpaceX’s first launch of the new year is set to be the Zuma mission, and unlike many of the company’s other launches, SpaceX has gone out of their way to keep the media’s attention away from the Falcon 9’s 2018 debut. In fact, unlike normal launches, SpaceX didn’t even acknowledge the Zuma mission existed until an FCC regulatory filing revealed the anticipated launch to the public just before its original launch date in November. The launch then had to be postponed while SpaceX took the additional time to review data from a rocket fairing test, they claimed.

The secrecy is almost certainly due to the payload, which although undisclosed was sourced from Northrop Grumman and funded by the U.S. government. What’s unusual about how tight-lipped SpaceX has been, however, is that this isn’t the first time Musk’s company has been tasked with putting classified payloads into orbit, but it is the first time they’ve tried to keep it under wraps.

In May of last year, SpaceX launched a classified satellite for the National Reconnaissance Office, and although the payload was described only as “a satellite,” the launch was announced well in advance and was even live-streamed online. Then, in September, SpaceX did some more whisper-level work for the U.S. Air Force, deploying their secretive X-37B orbital space plane, and again, despite the secrecy surrounding the payload, the launch itself was a public spectacle.

In fact, SpaceX was certified to conduct classified launches of these sorts all the way back in 2015, and to date, no other launch has been kept so close to the chest – begging the question, what did Northrop Grumman make for SpaceX to launch?

Falcon Heavy preparing for static fire testing.

All we do know is that it isn’t any heavier than a normal payload and that its intended target is low earth orbit (LEO). This much can be surmised based on the planned return trajectory for the Falcon 9 rocket tasked with delivering the payload into orbit. If the payload were being deployed much higher than that, the Falcon 9 would lack sufficient fuel to make the return trip and landing at Cape Canaveral, right down the street from where the Falcon Heavy is preparing for static fire testing of its massive collection of 27 Merlin engines.

Of course, a final destination of low earth orbit means little – it’s by far the heaviest trafficked portion of orbital space, with everything from communications satellites to the Air Force’s X-37B already zooming across the skies in that region of space.

All we know for sure, is that SpaceX now intends to launch this secretive payload on Friday, January 5, at 8:00 p.m. The rest remains classified.