Astronomer Toni Santana-Ros said of asteroid 1998 KY26, an 11-meter space rock exhibiting unusual acceleration, that we do not know what to expect.
Aktuálně.cz – Víte, co se právě děje reported on the mystery surrounding the tiny object, which rotates on its axis once every 5.35 minutes. Its trajectory shows an unexplained push in a direction perpendicular to its orbital plane. This peculiar movement led researchers to investigate whether the rock is actually a dark cometary body leaking gas into space.
Dark Comet Theory Faces Test
Common comets contain frozen volatile materials that sublimate when approaching the sun, creating a jet-engine effect that alters their path. Dark comets behave similarly but lack the typical dusty coma and prominent tail associated with icy wanderers.
Korbin Hansen and Masatoshi Hirabayashi from the Georgia Institute of Technology tested whether 1998 KY26 could preserve the water ice necessary for such propulsion. They published their studied in the journal Icarus to examine the internal thermal limits of the asteroid.
Thermal Models Rule Out Ice
The researchers built a three-dimensional thermal model accounting for the asteroid’s size, orbit, surface reflectivity, and thermal conductivity. Water ice inside the body requires temperatures below minus 128 degrees Celsius to survive over long periods. The model showed that even the coldest regions on the asteroid average at least minus 61 degrees Celsius during its solar orbit. That environment is far too warm to preserve ice in a vacuum.
“The results of our thermal model indicate that water loss from asteroid 1998 KY26 would occur too rapidly for the body to retain ice hidden beneath the surface,” Hansen and Hirabayashi stated in the Icarus paper.
Calculations show the asteroid would lose all of its ice within roughly 2,000 years, even if water initially made up one percent of its mass. If escaping water vapor drove the observed acceleration, the required reserves would deplete in just 62 years.
Scientists still cannot completely rule out the presence of ice if the asteroid entered its current orbit only recently. Spectroscopic observations suggest the body originates from the inner main asteroid belt and may be naturally dry. Alternative explanations include solar radiation pressure and thermal emission forces pushing on the rock.
Hayabusa2 Prepares for Close Encounter
Japan’s Hayabusa2 spacecraft will arrive at the asteroid in July 2031 to provide definitive data on its physical properties. Previous ground-based observations already proved the target looks entirely different than initial estimates suggested.
“We found that the actual shape of the body is completely different from what earlier observations described,” Toni Santana-Ros, an astronomer at the University of Alicante in Spain, told Aktuálně.cz – Do you know what’s happening right now?.
Santana-Ros and his colleagues discovered the asteroid is nearly three times smaller and rotates twice as fast as older estimates claimed. Hayabusa2 is continuing its extended mission after successfully returning samples from asteroid Ryugu to Earth in December 2020. The spacecraft will conduct close-range observations of 1998 KY26 to determine which forces actually govern its movement.