Here’s what you’ll learn when you read this story:

• Object Arjuna 2025 PN7 was thought to be a meteorite in an Earthlike orbit, but that is now being questioned.
• The new hypothesis suggests that 2025 P7 could actually be Zond 1, a Soviet spacecraft that was destined for Venus but broke down.
• Even if the object is not the actual probe intended for Venus, it might still be a throwaway rocket phase from that mission.

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Every object that trespasses on the inner solar system brings with it questions about its origin. Though it is suspected to be a chunk of rock from some far-flung region of space, no one ever really found out what ‘Oumuamua is made of, and while 31/Atlas may be a comet, Harvard astrophysicist Avi Loeb hypothesized about the possibility of it being an alien spacecraft. Now, Loeb thinks the newest target of interest could also be a technosignature—one from Earth.

Object Arjuna 2025 PN7, named for the Arjuna asteroid belt, was detected by the Pan-STARRS survey as far back as 2014, but it was so faint that it went unnoticed by astronomers until now. Researchers Carlos and Raúl de la Fuente Marcos of the Complutense University of Madrid published a recent study exploring the possibility of it being a quasi-moon. The Arjuna belt is made up of over a hundred asteroids in Earth-like orbits, quasi-satellites that move along with our planet but are not gravitationally bound to it, as opposed to mini moons that are gravitationally captured and orbit Earth temporarily.

“This ‘Arjuna’ object has, by definition of a quasi-satellite, an orbital period of a year…resulting in its extended presence close to Earth, despite following a heliocentric orbit,” Loeb and colleague Adam Hibberd said in a study recently submitted for publication.

Loeb and Hibberd propose that the Arjuna object is actually a relic of a defunct civilization. That civilization would be the Soviet Union, which sent a failed mission to Venus in April 1964. This was the era when the Soviets were already vying to put the first boot prints on the Moon while also sending spacecraft to Mars and Venus. The Zond-1 probe didn’t quite make it. En route to Venus, it was forced to use its rocket engine to give it more of a boost and later needed a course correction. There were operation errors and glitches in communication with the probe when its pressurized orbit compartment began to leak. It ended up depressurizing, and communication blacked out.

Hibberd’s models of interplanetary mission trajectories from the 1960s singled out Zond 1 as the candidate spacecraft most likely to be the mystery object. These models showed that 2025 PN7 fell into a quasi-satellite orbit around the time of the Zond 1 launch. Its closet approach to Venus occurred in July of 1964, the same time that Zond 1 was supposed to arrive at its destination. Its heliocentric longitude, or the angular distance between a celestial object and the Sun, evolved over the path that the probe would have taken if it survived, and both Zond 1 and 2025 PN7 have similar levels of brightness.

“For every such trajectory, the spacecraft positions and velocities were compared against those of 2025 PN7, in order to ascertain whether this object could be associated with the mission in question,” Hibberd and Loeb said.

The Zond 1 hypothesis will need spectroscopic backup. If measurements of its light spectrum could at least reveal its surface composition, that may give away whether it is a piece of outdated technology, as opposed to being another asteroid. What is problematic about declaring the identity of 2025 PN7 to be Zond 1 is that it flew closer to the Sun than was predicted based on its trajectory.

So could the Arjuna object actually be what remains of Zond 1? Loeb and Hibberd remain skeptical but want their research out there, suggesting that if 2025 PN7 is not the probe itself, it could be the discarded upper stage of the rocket that launched it.

Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.