The test is a crucial performance check before the maiden launch of Falcon Heavy, expected at the end of this month or early next.
A military satellite launched by Elon Musk's Space Exploration Technologies Corp. hasn't been spotted in orbit by the US Strategic Command, creating a mystery about the fate of the classified payload and doubts about whether the mission was a success.
The Wall Street Journal was the first to report late Monday that the billion-dollar payload did not make it into orbit and was "presumed to be a total loss", citing unnamed government and industry officials. "We can not comment on classified programs".
There are conflicting reports about what may have happened.
According to a source, the satellite did not reach the designated altitude and instead, fell back down, along with the expended second stage of the SpaceX rocket.
A SpaceX representative told Business Insider, "We do not comment on missions of this nature, but as of right now reviews of the data indicate Falcon 9 performed nominally".
SpaceX, which was founded by Elon Musk, says its rocket performed correctly.
Adding to the mystery, the satellite, categorized as United States of America 280, was still listed as a payload on orbit by the US 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. But second-stage information was kept to a minimum because of all the secrecy surrounding the flight.
If the satellite is no longer in orbit, she said the listing will eventually be removed when the catalog is updated.
SpaceX/Flickr (public domain) A Falcon 9 rocket launched by SpaceX leaves behind an exhaust plume as it races toward space with a top-secret government payload code-named Zuma. The sources would not confirm what exactly the payload was, saying it was classified.
This is not the first time a payload was lost on a SpaceX mission. The company has recently ramped up its launch pace, even launching two missions from opposite coasts within about 48 hours.
SpaceX has launched national security payloads in the past, including a spy satellite for the National Reconnaissance Office, and an X-37B space plane for the US Air Force. The company later said it had cleared the issue.
Jonathan McDowell, an astronomer at the Harvard-Smithsonian Center for Astrophysics, said on Twitter that SpaceX did not supply the payload adaptor, which shoots the satellite off the rocket, for this mission. In the static fire test, SpaceX engineers will ignite all 27 of the heavy-lift rocket's engines almost simultaneously for the first time, holding the rocket down on the launch pad while they do.
"Since the data reviewed so far indicates that no design, operational or other changes are needed, we do not anticipate any impact on the upcoming launch schedule", Shotwell added.