Southwest Research Institute | 2019 Jan 17
Using images and thermal data collected by NASA’s Lunar Reconnaissance Orbiter (LRO), Southwest Research Institute scientists and their collaborators have calculated the ages of large lunar craters across the Moon to be less than 1 billion years. By comparing the impact history of the Moon with Earth’s craters over this interval, they discovered that the rate of sizable asteroid collisions has increased by a factor of two to three on both bodies over the last 290 million years.
For decades, scientists have tried to understand the rate that asteroids hit the Earth by carefully studying impact craters and by using radiometric dating of the rocks around them. Earth has fewer older craters than expected compared to other bodies in the solar system, making it difficult to find an accurate impact rate and to determine if it has changed over time. Many experts assumed that the earliest Earth craters may have been worn away by wind, storms and geologic processes, mechanisms not present on the Moon.
“What this research uncovered is that the Earth has fewer older craters on stable terrains not because of erosion, but because the impact rate was lower prior to 290 million years ago,” said SwRI’s William Bottke, an asteroid expert who coauthored a paper outlining the research published January 18 in the journal Science. “The Moon is like a time capsule, helping us understand the Earth. We found that the Moon shared a similar bombardment history, which meant the answer to Earth’s impact rate was staring everyone right in the face.” ...
Earth and Moon Impact Flux Increased at the End of the Paleozoic ~ Sara Mazrouei et al
- Science 363(6424):253 (18 Jan 2019) DOI: 10.1126/science.aar4058
