Japan's Hayabusa2 spacecraft

Final target of Japanese Spacecraft would be Asteroid 1998 KY26 or an object of Technological Origin   

After successfully rendezvousing with near-Earth asteroid Ryugu in June 2018 and sending a sampled cache of rocks back to Earth, Japan’s Hayabusa2 spacecraft is now making its long journey to its next destination, a tiny and rapidly spinning asteroid dubbed 1998 KY26. The spacecraft is expected to reach the mysterious space rock by July 2031, giving scientists plenty of time to come up with theories as to what it could find once it gets there. Japan's Hayabusa2 spacecraft is heading towards its final target; a small, rapidly rotating asteroid, believed to be around the size of a spacecraft. According to a new and intriguing paper (though not necessarily with correct conclusions) there may be a very good reason for that, with the headline being that it may be of technological origin.

1998 KY26 is an intriguing new candidate for an entirely new class of objects. In 2017, interstellar visitor ‘Oumuamua, the first object from beyond the solar system to have ever been observed, inspired scientists to categorize it as a “dark comet,” a class of asteroids which share some behaviors with comets. (A brief refresher: asteroids are lumps of rock, ice or dust that orbit the Sun but are too small to be classified as planets, while comets are “dirty snowballs” that release gases to form a tail behind them as they pass by the Sun.). Hayabusa2, the Japanese space agency's (JAXA's) asteroid sample collecting spacecraft has already been on one hell of a journey, collecting samples of material from asteroid Ryugu, before dropping off those samples during a flyby of Earth. In 2020, shortly before those samples were returned to us, JAXA announced a new target for the spacecraft, and a long extension to the mission. "The destination will be the small asteroid 1998 KY26. This is a long-term mission that exceeds 10 years and, after an itinerary of various events, we aim to rendezvous with the rapidly rotating 1998 KY26," JAXA said. "We may also attempt particular challenges, such as dropping a target marker or touchdown."

The task, it turns out, is more difficult than initially anticipated. In 2024, a team of astronomers used the Very Large Telescope at the European Southern Observatory, expecting to confirm previous estimates of the object's size and mass, but found that it may be a very tricky object to land on. “We're surprised to discover that the object looks completely different from what was expected; it was much smaller, three/four times smaller than expected. It's spinning faster, twice as fast. And also the composition itself… It's much brighter," lead author Dr Toni Santana-Ros, a planetary scientist at the University of Alicante and University of Barcelona, explained. "The funny thing is that the object is about 11 meters in diameter, and the spacecraft itself is 6 meters [20 feet]. So it's more than half of the object it’s going to visit. It's quite a funny thing!” But according to Harvard astronomer Avi Loeb, who has spent years pondering the nature of ‘Oumuamua and its unusual behavior, 1998 KY26 could be something else entirely. Loeb and his colleagues suggest the object could instead be a long-lost relic of the Soviet space program.

According to a new preprint paper that is yet to be peer-reviewed, JAXA may be in for one more surprise as they approach the object when it approaches it in July 2031. Looking at the object's path and comparing it to potential paths of an old Soviet-era spacecraft which failed en route to study Mars's "doomed moon" Phobos, the team suggests that humans may have gotten pretty close to the object when we assembled it. Launched on July 7, 1988, Phobos 1 operated normally for a few months, before falling out of contact with Earth on 02 September, 1988, the result of an incorrect sequence sent to the spacecraft, a single hyphen out of place. The mistake may have unintended consequences decades down the line, with the suggestion that the asteroid targeted by JAXA may actually be another spacecraft, setting the scene for the Spider-Man points at Spider-Man meme in space. "Our new paper shows that two propulsive velocity thrusts (∆Vs) combined at 1.9 km's/second, the first just after loss of mission and the second in May 1996, allow the orbits and phases of the two bodies to align, with an arbitrarily low separation in velocity-position space," astronomer Avi Loeb explains. "There is also evidence that 1.9 km's/second was within the performance envelope of Phobos 1, which had a powerful nitric acid and amine-based autonomous thruster for Mars Orbital Insertion."

While the team points out that their work is far from conclusive, there may be a few reasons to take the hypothesis seriously, at least, including evidence that the spacecraft delivered some thrust shortly after the mission was unexpectedly cut short. “In particular, we identify it as potentially a relic of a historical Russian mission to Mars, the Phobos 1 probe, which suffered a failure 2 months after the launch in July 1988, due to upload of a faulty command,” Loeb explained.  Phobos 1 failed to send back a signal in August 1988 due to what later turned out to be a typo, a missing hyphen, in a command that shut down crucial systems. Loeb and his colleagues suggest that the probe’s thruster firings may have put it in a “similar” orbit to 1998 KY26’s, and that the “two orbits converge and are statistically compatible.” The researchers also argue that the defunct spacecraft and dark comet share roughly the same size and a “quite elongated” shape. According to the team, the spacecraft idea could explain the object's high reflectivity, as well as why it has kept itself together despite its fast spin, behavior not expected of a rubble pile asteroid (though a more solid structure, or factors we have yet to discover, could also explain this, too). The team adds that the object appears to be "quite elongated", given the changes in its brightness as seen by humanity's telescopes.

Still, the hypothesis is quite a stretch, given the vastness of space. However, Loeb argued that scientists should nonetheless extend their “training data set to include not just rocks and icebergs but also the space objects launched by humans over the past 69 years” just in case. If 1998 KY26 does turn out to be technological in nature, Loeb argued that the finding could support his controversial theory that ‘Oumuamua may have also been a piece of technology sent to us by an advanced extraterrestrial civilization. I wonder whether the mainstream of comet experts will acknowledge that 1I/’Oumuamua may have not been a natural ‘dark comet’ if it becomes clear that their so-called ‘dark comet’ 1998 KY26 is technological in origin, beyond any reasonable doubt,” he pondered. It's a fun idea, and it would be quite something to see in 2031. If it turned out to be correct, it would be the first time humanity has accidentally attempted to land on the surface of a second, equally-sized spacecraft, for example. But for now, the work is an interesting "what if" rather than a solid conclusion, or probable scenario.

"In anticipation of the Hayabusa2 observations in 2031, which will be decisive in resolving the origin of this object, we encourage further observational, dynamical, and theoretical studies aimed at more tightly constraining the nature and properties of 1998 KY26," the team concludes. Nobody knows for sure what Hayabusa2 will find. Besides, thanks to the asteroid’s extremely fast spin, it could prove extremely difficult to land on. But Loeb and his colleagues argue we should keep an open mind, just in case it turned out to be a long-lost Soviet era spacecraft.