Student helps find landslides on Mars

Stephanie Zawada

A UA student, over the course of his undergraduate career, has helped discover the cause of landslides on the surface of Mars.

Kaylan Burleigh, a senior studying physics and astronomy, began Mars research using data from the HiRISE telescope aboard the Mars Reconnaissance Orbiter, a spacecraft that reached Mars in March 2006.

“The idea was that we’d seen these really small impact craters that you couldn’t see with previous telescopes,” Burleigh said. The research began because scientists had observed what looked like landslides occurring on Mars and wanted to know if meteoric impacts had any effect on these changes to Mars’ physical surface. If the impacts of roaming craters were causing these landslides, the research team that Burleigh was a part of wanted to know how exactly the so-called landslides were forming.

By counting the landslides he found around a specific crater, Burleigh said, and through mapping the distributions of those counts, it was obvious that the crater caused the landslides. After analyzing the data, Burleigh presented his work for peer reviews. This is where his ordinary research took a groundbreaking direction, he said.

Instead of landslides, the term “avalanche” was more accurate, Burleigh said. From an impact just on the ground, he added, you wouldn’t be able to form the avalanches that were occurring. The development of these avalanches needed another reason, Burleigh said.

To solve the mystery of what exactly was causing these episodes, researchers compared models of events that occur on Earth to what was happening on Mars.

Researchers model a fast compact object, Burleigh said, and because of the shockwaves it creates, they can get these very prominent waves that hit the ground and cause the dust to get disturbed enough that it can cause avalanches. He concluded that the effects caused by the approach of an incoming meteor on the surface of Mars had roughly the same impact on Mars’ dusty surface that a sonic boom on Earth has with regards to air particles — it’s a shockwave. The strength of the vibrations that the incoming crater causes in the atmosphere results in a ripple effect on Mars’ surface even before the crater touches the ground.

The material on Mars would just be sitting there, Burleigh said, without these impacts. “It’s a pre-impact process,” he explained.
But it is unlikely that the shockwaves like the ones Burleigh has studied have ever drastically changed Mars’ surface. They probably have very little effect on the shape or global properties of Mars, Burleigh said. The impacts were previously undetectable without the HiRISE instrument, he added.

Of the 201 detected impacts he observed, Burleigh said there was a relatively small number of the cases that actually caused the avalanches. Only 16 of the studied impacts that whipped shockwaves into the air were strong enough to cause avalanches on Mars’ surface.

“They’re probably not going to affect anything too vastly important on Mars,” Burleigh said. At the same time, he added, it does tell you that this other mechanism including the “air shock” is important.

For now, these pre-impact shockwaves only give researchers a glimpse into how meteors affect the surface of a planet under Mars’ conditions. The craters and meteors forming the avalanches are relatively small, Burleigh said, being only a few meters in diameter. Even with really big meteors, he said, this effect would probably be unnoticeable. With large meteors, Burleigh said that the energy they would send to a respective surface area of Mars would cause a much more striking effect than just a shockwave through the air.