The launch itself seems entirely routine. After blasting off from Launch Complex 39A at the Kennedy Space Center and putting the craft into orbit, the reusable Falcon 9 booster will attempt a landing at SpaceX’s Landing Zone 1 at the U.S. Air Force’s Cape Canaveral Air Force Station, also in Florida. The company has been steadily increasing the number of its launches since the rocket's first flight in 2010.

“Both Falcon 9 and the payload remain healthy,” a SpaceX spokesperson told Space.com. “Teams will use the extra day to conduct some additional mission assurance work in advance of launch.”

SpaceX originally scheduled the Zuma launch aboard one of its partially reusable Falcon 9 rockets for Nov. 15, 2017, but delayed the mission a day for unspecified reasons. According to its website, the California-headquartered firm says there are two additional back-up launch windows on Nov. 17 and Nov. 18, 2017.

Space launch firm SpaceX is preparing to boost a Northrop Grumman spacecraft , code named Zuma, into low earth orbit from NASA’s Kennedy Space Center in Florida. But what the payload actually is, what it’s supposed to do and for how long, and what U.S. government agency or agencies are involved in the project all remain a mystery.

NRO routinely announces its launches, even if it generally declines to provide any specific details about the payloads. On May 1, 2017, another one of SpaceX’s Falcon 9s lofted the classified NROL-76 spy satellite into orbit. In September 2017, the firm launched the U.S. Air Force’s shadowy X-37B space plane on its latest mission, known as Orbital Test Vehicle 5 (OTV-5).

So far, though, no U.S. government entity has officially claimed ownership of the payload. The National Reconnaissance Office (NRO), which manages America’s spy satellites, told Aviation Week that it had no connection to this particular mission.

Follow-up reports from numerous outlets uncovered the existence of Northrop Grumman’s Zuma spacecraft and that the company was on contract to an unspecified U.S. government agency. The Virginia-headquartered defense contractor had previously made a deal with SpaceX for space launch services in 2015, but did not publicly schedule any associated missions. With all the formalities involved, and how hard it would be to keep that information secret, it seems as if this latest launch has been running on a truncated timetable.

But there is virtually no information about the payload itself. The entire mission remained out of the public eye until NASASpaceflight.com first noticed that SpaceX had filed documents with the Federal Communications Commission (FCC) to get a “special temporary authority” for radio communications associated with the launch, which the request described only as "Mission 1390."

“The Zuma payload is a restricted payload,” Lon Rains, the communications director for Northrop Grumman's space systems division, told Space.com in a statement. “The event represents a cost-effective approach to space access for government missions. As a company, Northrop Grumman realizes that this is a monumental responsibility and has taken great care to ensure the most affordable and lowest risk scenario for Zuma.” There are some potential clues as to the nature of the craft in a series of official U.S. Air Force notices and alerts that the service published to warn the public of areas of potential danger. This is to help civilian aircraft and boaters avoid potential hazards during the launch. Using these documents and other available information, Spaceflight101.com offered some educated guesses as to the nature of the Zuma craft itself. The site noted that the closure areas were very similar to that of NROL-76, suggesting that the mission would involve an extremely high lofted trajectory to get the craft into orbit. This would involve the rocket flying on a more vertical flight path that would keep the first, reusable stage very close laterally to the landing area. Combined with reports that the rocket will not burn all of its fuel during the launch, this could indicate a lighter weight payload that requires less time and energy to get up to the appropriate speed and altitude.

USAF A map of the launch hazard area for the Zuma mission as scheduled for Nov. 16, 2017.

USAF Airspace closures for the Zuma mission as it was scheduled on Nov. 15, 2017.

This doesn't offer any particular indication one way or another as to the craft's mission or actual capabilities, though, and there's little concrete information to go on from other available sources. At first glance, there isn't much to glean from the official mission patch, which often contain cryptic symbols relevant to the particular launch. The only spacecraft the artwork depicts is the Falcon 9, along with its company logo, a blue star marking the launch site in Florida, and an American flag waving in the background. A four leaf clover that appears at the bottom of the heraldic shield, a device that appears on many other SpaceX mission patches, is one of the only other symbolic elements and it’s unclear as to its significance.

SpaceX The official Zuma mission patch.

But there is one potentially more interesting feature. A constellation of six twinkling stars is at the top left, making up a significant portion of the patch. Top secret "black projects" developed at or operating in relation to the Area 51 test site at Groom Lake have long used a similar obscure motif, with the markings acting as an abstruse statement, standing for "5+1" or "51." Although we can't say with any certainty that this payload is connected to the secretive base and the myriad projects that are underway there, there have been reports that the legendary facility in Nevada has supported the development of experimental motherships used to haul payloads or small spacecraft into orbit or on suborbital flight profiles. In 2014, construction began there on a massive new hangar that could possibly house such a vehicle. The U.S. Air Force and the Defense Advanced Research Projects Agency (DARPA) has since publicly announced that they are actively working on developing this capability, but more on that in a moment.

Unit Patch via Trevor Paglen's book I Could Tell You but Then You Would Have to Be Destroyed by Me

Northrop Grumman is known to be especially active in the classified domain and has its own connections to Area 51, having worked there on the Tacit Blue stealth demonstrator – there is even see a six star symbol painted in its cockpit – during the 1970s and 1980s and certainly many other flying programs since. The top secret facility is likely where the company developed its top secret high-altitude surveillance drone, known as the RQ-180, and may have or continue to host development of the B-21 Raider stealth bomber or its technology demonstrator predecessors. Again, however, numerous other SpaceX mission patches, including those for launches supporting public civilian projects, use similar star arrangements. The entire patch design actually shares a significant number of features – the Falcon 9 and company logo, a highlighting of the launch area in Florida, an American flag motif, the clover, and the six stars on a black background – with the one for the earlier NROL-76 mission, which is itself interesting given that NRO's insistence that it has no relationship to the Zuma spacecraft. At the time of writing, SpaceX had not responded to questions about the symbolism.

NRO and SpaceX NRO's art for NROL-76, left, and SpaceX's patch, right.