Monitoring meteor impacts on the Moon yields lessons for our past and future
The surface of Earth’s moon is an open book, with each crater telling some of the satellite’s history in the solar system. Without atmosphere to protect it, or wind and water to smooth the surface back over, thousands of craters remain visible in the rock and dust. The fact that the Moon has maintained this record of asteroid impacts is actually proving to be quite useful, showing us evidence of events that we want to know about but really don’t want to witness first-hand. Like mass extinctions.
Sizable geological scars
To be clear, nobody thinks a mass extinction ever took place on the Moon, but it does have a crater that is a model for such events here on Earth. The asteroid that (mostly) wiped out the dinosaurs at the end of the Mesozoic era was big enough to create a massive hole, called the Chicxulub crater. While work is being done to study that Chicxulub directly, the fact that it is under the rock, dirt sand and water of the Yucatan Peninsula makes it very hard to access. We know it has an inner circle of mountains near the center, and that those mountains were formed by the initial impact. But it’s still hard to really see, which is where the Moon’s craters come into play.
Around 3.9 billion years ago, the Moon was closer to Earth, and getting hit by a larger share of big asteroids. One was big enough to create the Schrödinger crater, which is around 200 miles across. Like the Chicxulub crater, the Schrödinger crater has mountains at its center in a ring 90 miles across. Clear imaging from the Lunar Reconnaissance Orbiter and the Chandrayaan-1 spacecrafts provided enough data to simulate how these types of features would have been formed. On the Moon, the Schrödinger crater’s mountains were ripped from over 18 miles below the Moon’s surface, being flung nearly 13 miles into the sky— twice the height of Mount Everest. This process probably took all of an hour on the Moon, but the similarly-shaped Chicxulub crater on Earth most likely did something similar in just a few minutes, mostly thanks to our planet’s stronger gravitational pull.
An impact big enough to create a crater like Schrödinger or Chicxulub isn’t expected any time soon, but regular imaging of the Moon’s surface is showing that impact craters aren’t ancient history. In the last seven years, over 222 new impact craters have been documented, ranging from six to 141 feet across. These aren’t big enough collisions to raise mountains, but they are big enough to raise concerns for future missions, or structures, on the Moon. Nobody thought the Moon was free and clear of all asteroid impacts, but these newly formed craters, as well as 47,000 ‘splotches’ formed by raining debris after an impact, is around 33 percent more than researches expected in that time frame. As people look to possibly return to the Moon in the coming years, we’ll want really consider what abuse the Moon is likely to go through while we’re there.
Source: Scientists Study the Moon to Learn About Dinosaur-Killing Asteroid Impact by Jay Bennett, Popular Mechanics