Eyewitness video shows bright points of light moving across the skies over Temuco, Chile.
When Orbital Sciences' test spacecraft fell from orbit last week, the company saw the fiery blaze as a cause for celebration — but it was also the cause of a UFO mystery, at least for a little while.
The spacecraft was a dummy payload, which was launched into orbit on April 21 aboard Orbital's newly developed Antares booster during its maiden flight. The satellite's primary purpose was to simulate the mass of the company's Cygnus cargo capsule, which will eventually be launched by the Antares to resupply the International Space Station.
Orbital never intended the Cygnus Mass Simulator to stay in space. Its orbit gradually decayed over the course of more than two weeks, and on the night of May 9-10 it finally made its descent through the atmosphere. As it fell, aerodynamic forces heated it up, and tore it apart. It broke into several dozen flaming fireballs, streaking together from horizon to horizon across the evening skies of Chile and Argentina.
Just by luck, the spectacle unfolded over a populated region. It was widely seen, and widely recorded. Within hours, a dozen videos of the sky show were posted on YouTube.
The videos thrilled the Antares team. "It was a spectacular ending to a great beginning,” said Barry Beneski, the company's publicity director. Operators in their flight dynamics lab, who had designed the mission, were more down to Earth: "Way cool!" was their first comment.
But for many of the eyewitnesses, the aerial blaze was a real mystery, since no advance word of the spacecraft's destruction had been issued. Was it a comet or a meteor shower? A blimp or fleet of Chinese lanterns? Theories raced around the Internet.
The leading theory, as might be expected, was that the object was a descending spaceship. The scattered dazzlers assembled themselves in the perceptions of many witnesses as outlining a large structure with mounted lights. It was widely seen as an awesome military secret, or even an interplanetary visitor.
It was an honest misperception.
Was the Pentagon in the dark?
It didn't help that the U.S. Strategic Command apparently misidentified the object in orbit. In advance of re-entry, the Pentagon's space catalog listed it as a tiny test satellite that should have burned up without a trace.
This map of South America shows segments of the Cygnus Mass Simulator's final orbits, ending with re-entry over Argentina. The final track matches up well with UFO sightings on the night of May 9-10.
Within hours of the satellite's re-entry, Canadian amateur satellite tracker Ted Molczan matched up the UFO reports with the satellite catalog entry. "The time and location of the sighting correlates with the re-entry of 'object Bell,'" he reported on the SeeSat discussion board.
Molczan added that the Strategic Command had issued a "prediction" several hours after the actual re-entry, saying that the satellite would hit the atmosphere soon after midnight GMT on May 10. The trajectory had the minisatellite coming down over the area of South America where the UFO sightings were reported.
The problem was, the Bell minisatellite described by the Strategic Command and NORAD was only 4 inches (10 centimeters) wide, about the size of a tissue box. When Molczan rechecked the records, he determined that the minisatellite should have fallen from orbit just days after its launch. The Antares booster stage was destroyed during re-entry on May 1. That left only one other sizable object associated with the Antares launch: the 8,377-pound (3,800-kilogram) Cygnus Mass Simulator.
The Strategic Command's public affairs office has not yet confirmed the correct identity of the object that was seen falling out of orbit, despite repeated inquiries from NBC News.
Orbital Sciences, the spacecraft's owner, would have been legally responsible for any damage caused by falling debris. For that reason, the company took great pains to reduce the potential debris hazard.
A schematic shows the latticework structure inside Orbital's Cygnus Mass Simulator.
The mass simulator payload was built using an open lattice structure, designed to tear apart quickly during re-entry. Each of the separate pieces was meant to burn up completely, providing observers with a view of fiery streaks flashing across the sky. And that's exactly what happened.
No advance warning was given, because no threat was expected. Orbital's Beneski said the company merely planned to post a note on the project's Facebook page, at some point after re-entry. The inquiries from NBC News caught Orbital's officials by surprise — but they then responded fully and quickly.
UFO buffs shouldn't be disappointed. The event demonstrated that large satellite re-entries can really look like giant spaceships with mounted lights. Such reports fill the files that have been kept by UFO researchers over the past half-century — and many of those reports could well be unrecognized satellite re-entries as well.
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NBC News space analyst James Oberg spent 22 years at NASA's Johnson Space Center as a Mission Control operator and an orbital designer.