14 DAY TRIAL // Scientists analyzing data from the NASA Cassini spacecraft announce the discovery of traces of avalanches on the surface of the icy Saturnine moon Iapetus. They explain that the phenomenon is not at all unusual throughout the solar system. Previous studies found similar occurrences on Mars.
However, discovering that avalanches may occur on the walnut-shaped, two-toned Saturnine moon was entirely unexpected. What's more, no one was expecting to see such large debris fields being produced during the events.
One of the most remarkable things scientists identified in the new images is that the debris flow produced by these events traveled for prolonged distances, in some cases exceeding 50 kilometers (30 miles), Universe Today reports.
Investigators at the Washington University in St. Louis (WUSL), led by expert Bill McKinnon, explain that there is currently no way to explain how or why these avalanches occur on Iapetus. The moon displays a special pattern in its debris fields, indicative of so-called long-runout landslides.
“This is really about the mystery of long-runout landslides, and no one really knows for sure what causes them,” McKinnon told colleagues gathered at the Lunar and Planetary Science Conference, which takes place this week in The Woodlands, Texas.
An interesting statistic shows that the amount of material moved by Iapetus' landslides is higher than that found to have been moved by Martian landslides, even though there is no comparison between the two in terms of size.
“The mechanics of long-runout landslides are poorly understood, and mechanisms proposed for friction reduction are so numerous I can’t fit them all on one Powerpoint slide,” McKinnon explained.
There are many reasons for which avalanches could have occurred at the Saturnine moon. Acoustic fluidization or compressed air may have triggered the event. On the other hand, the soils on which these ices stood may have been wet, or saturated with water. The fact is, we just don't know.
Average temperatures on Iapetus reach 130 K (-143 °C; -226 °F) on its dark side, and 100 K (-173 °C; -280 °F) on its brighter side. These values are valid for the moon's equator. At the poles, the situation is bound to be even worse.