Adding to the mystery, the satellite, categorized as US 280, was still listed as a payload on orbit by the U.S. space surveillance system as of Tuesday afternoon, said Laura Grego, a Caltech-trained physicist who is a senior scientist at the Union of Concerned Scientists.
Apart from that, Bloomberg also reported that the second stage process involving the booster failed to progress in a proper way which caused both the Zuma satellite and Falcon 9 rocket's second stage to fall back into the closest ocean. It is not as powerful as the Saturn V, the rocket which propelled astronauts into space for the 1960's and 1970's Apollo missions, but it is lighter and more efficient.
For clarity: after review of all data to date, Falcon 9 did everything correctly on Sunday night. SpaceX isn't commenting on the allegedly failed mission, however.
Northrup Grumman, the maker of the payload, said it was for the United States government and would be delivered to low-Earth orbit, but offered no other details.
"We do know that aerospace and defense company Northrop Grumman procured Zuma's launch atop a Falcon 9 for the USA government - but we don't know which agency will operate the satellite, or if its mission is civilian or military". "Information published that is contrary to this statement is categorically false".
The Falcon 9 launcher returned to Earth successfully after the company's first mission for 2018.More news: Mueller seeking to interview Trump in Russian interference probe
While it appeared that the launch went off without a hitch, the full launch and separation of the nose cone, which surrounded the secret satellite, was not streamed as it normally is, due to the classified nature of the mission. The company chose SpaceX as the launch provider, noting late a year ago that it took "great care to ensure the most affordable and lowest risk scenario for Zuma".
During a livestream of Sunday's launch, SpaceX said it got successful confirmation that the fairing - the clamshell-like covering for payloads at the tip of the rocket - did deploy.
Results from the firing will be analyzed ahead of Falcon Heavy's demonstration flight around the "end of the month", according to CEO Elon Musk.
The company says that SpaceX is all set for the maiden flight of its Falcon Heavy.
SpaceX has pushed back an historic test of the Falcon Heavy, the world's largest rocket.