07/29 00:51
Scientists from NASA’s OSIRIS-REx mission recently learned that surface renewal occurs much faster on asteroids than on Earth.
By analyzing rock fractures on Bennu from high-resolution images taken by the OSIRIS-Rex spacecraft, the team discovered that the sun’s heat breaks down rocks on Bennu in just 10,000 to 100,000 years.
Rapid temperature changes in Bennu cause internal stress that causes rocks to crack and shatter, similar to the way cold glass breaks under hot water. The sun rises every 4.3 hours on Bennu. At the equator, daytime highs can reach around 260 F (about 127 C), and nighttime lows can drop to around 10 F (about -23 C).
OSIRIS-REx scientists have detected cracks in the rocks in spacecraft images from the first surveys of the asteroid.
The fractures appear to point in the same direction, Delboe said, “a clear indication that heat shocks between day and night could be the cause.”
Delboe and colleagues measured the length and angle of more than 1,500 fractures in the OSIRIS-Rex images by hand, some shorter than a tennis racket, others longer than a tennis court.
They found that the fractures mostly line up in a northwest and southeast direction, suggesting that they are caused by the sun, which appears to be the primary force changing Bennu’s landscape.
“If the landslides or collisions were moving faster than the rocks that are cracking, the fractures would have pointed in random directions,” Delboe noted.
The scientists used a computer model and their fracturing measurements to calculate the 10,000 to 100,000-year time frame for thermal fractures to sublimate and split the rocks.
Christophe Mattonti, one of the authors of the paper at the University of Côte d’Azur explained: “It is amazing to see that they can exist similarly in very ‘exotic’ physical conditions (low gravity, no atmosphere), even compared to Mars.”