A spacecraft could remain structurally sound for centuries
Recent observations show 1998 KY26 is 3-4 times smaller than expected, rotates twice faster, and exhibits unusual brightness inconsistent with natural asteroids. Researchers propose two propulsion maneuvers totaling 1.9 km/s could align the object's orbit with the Soviet Phobos 1 lost during a 1988 Mars mission.
- Asteroid 1998 KY26 is 3-4 times smaller than previously estimated, about 11 meters across
- The object rotates twice as fast as expected and exhibits unusual brightness
- Soviet Phobos 1 was lost on September 2, 1988, after incorrect commands were sent
- Two propulsion maneuvers totaling 1.9 km/s could theoretically align the orbits
- Hayabusa2 will reach 1998 KY26 in July 2031
A preliminary study suggests asteroid 1998 KY26, target of Japan's Hayabusa2 probe in 2031, may be an artificial object possibly linked to the lost Soviet Phobos 1 spacecraft from 1988.
Japan's Hayabusa2 spacecraft is headed toward an encounter in July 2031 with an object that may not be what anyone thought it was. The target, catalogued as asteroid 1998 KY26, has been the focus of a preliminary study suggesting it could be artificial—possibly the remains of a Soviet probe that vanished nearly four decades ago.
The Hayabusa2 mission, operated by Japan's space agency JAXA, had already achieved a major milestone by collecting samples from the asteroid Ryugu and returning them to Earth. In 2020, the agency announced an extended mission and set 1998 KY26 as the next destination, a journey spanning more than a decade. The plan included not just a flyby but potentially releasing target markers and attempting a landing. Then, in 2024, astronomers using the European Southern Observatory's Very Large Telescope took a closer look at the object and found something unexpected.
The asteroid turned out to be far smaller than previous estimates suggested—between three and four times smaller, in fact. It also spins roughly twice as fast as anticipated. Most striking, it reflects far more light than a typical asteroid should. Toni Santana-Ros, a planetary scientist at the University of Alicante and University of Barcelona, was among those who documented these anomalies. The object measures roughly 11 meters across, compared to Hayabusa2's six-meter frame. The unusual brightness and other characteristics caught the attention of researchers who began exploring an unconventional explanation.
The hypothesis centers on the Soviet Phobos 1 spacecraft, launched on July 7, 1988, to study Phobos, one of Mars's moons. The mission lasted less than two months. On September 2, 1988, contact was lost after a sequence of incorrect commands was transmitted to the vehicle. According to the preliminary study, two propulsion maneuvers totaling a velocity change of 1.9 kilometers per second could theoretically align the orbits of 1998 KY26 and Phobos 1—a feat well within the technical capabilities of the Soviet-era spacecraft.
What makes the case intriguing to the researchers is the object's high reflectivity and its structural integrity despite rapid rotation. A loose rubble pile, as many asteroids are thought to be, would struggle to hold together under such spin rates. The object also appears elongated based on brightness variations observed by telescopes—a shape consistent with a spacecraft but less typical for a naturally formed asteroid. Yet the authors of the study are careful to acknowledge the limits of their hypothesis. A naturally solid asteroid or unknown factors could equally explain the observations.
The study itself remains unpublished in peer-reviewed form, and the researchers are explicit that their proposal is far from conclusive. They emphasize that additional observations will be needed to confirm or rule out the artificial origin theory. When Hayabusa2 arrives at 1998 KY26 in 2031, it will gather data that could settle the question definitively. Until then, the possibility sits in a strange liminal space—intriguing enough to merit serious consideration, but not yet grounded in the kind of evidence that would move it from hypothesis to fact. The next five years will determine whether this distant object is a relic of Cold War space exploration or simply an asteroid with unusual properties.
Citas Notables
The hypothesis is far from conclusive and additional observations will be necessary to confirm or rule out this possibility— Study authors
The object presented characteristics quite different from those predicted— Toni Santana-Ros, planetary scientist
La Conversación del Hearth Otra perspectiva de la historia
Why would a Soviet spacecraft from 1988 still be intact enough to detect now, decades later?
In the vacuum of space, there's no weathering, no oxidation, no decay. A spacecraft could remain structurally sound for centuries. The real question is whether it could have been maneuvered into this particular orbit—and the researchers argue the math works.
But couldn't any small, reflective object in space trigger this kind of speculation?
Absolutely. That's why the researchers are careful to say this is preliminary. But the combination of factors—the unexpected size, the fast rotation it somehow survives, the brightness—creates a pattern that seemed worth investigating.
What happens if Hayabusa2 gets there and it's just an asteroid?
Then we learn something about how asteroids can behave in ways we didn't fully predict. Science doesn't fail when a hypothesis is wrong; it fails when we stop asking questions.
Is there any chance this becomes a major discovery?
If it turns out to be Phobos 1, yes—it would be the first time we've recovered a lost spacecraft from another planet's vicinity. But that's a big if. The evidence right now is suggestive, not conclusive.
Why did it take until 2024 to notice these oddities?
Better telescopes, better observation techniques. The Very Large Telescope gave them a clarity previous instruments couldn't provide. Sometimes the universe keeps its secrets until we build better eyes.