Our country hides its scars well. It’s a shame, really, because evidence of past asteroid strikes can help us better prepare for the next disaster.
In fact, NASA’s Goddard Space Flight Center chief scientist, James Garvin, thinks we may have been misreading the cosmic collisions that have occurred over the past million years.
If they are right, the chance of being hit by a nasty object may be higher than current estimates predict.
As Garvin made clear in his speech at the recent Lunar and Planetary Science conference: “It would be a very difficult thing to do.”
The most famous meteorite impact – the dinosaur killer that drilled a hole in what is now the Yucatan Peninsula some 66 million years ago – is well known for destroying life on Earth.
It was a 10-kilometer (about 6-mile) wide behemoth of the likes that hit our planet about 100 million years or so ago.
However, small impacts can still stir up enough dust to destroy the planet and cause famine for years. According to some estimates, kilometer-long asteroids fall to Earth from heat and dust about every 600,000 years, give or take.
There is no standard for these types of events, of course, and the estimates are the same as the data we use to make our predictions.
Although we can look to the heavens for evidence of giant rocks about to plunge us into a world of pain, Earth’s history is like a tape of meteorite impacts that begin time.
Unfortunately, this history is difficult to read from our perspective, all because of the Earth’s powerful winds, water, and tectonics that wear on its surface. Even the most recent events can be difficult to interpret through the accumulation of dust and biology.
Garvin and his team used a new catalog of high-resolution satellite images to get a closer look at the highly eroded fossils that formed within the last million years, in an attempt to determine their true size.
Based on their analysis, several masses have faint rings beyond what were thought to be their outer rims, making them larger than previously thought.
For example, the 12- to 14-kilometer depression in Kazakhstan called Zhaminshin is thought to have been created by a 200- to 400-meter-long meteorite that hit Earth 90,000 years ago – a recent impact that triggered a ‘cold nuclear’ event.
However, based on a new analysis, this huge event would have been much more dangerous, leaving a crater that is about 30 kilometers across.
The diameters of three other large craters were also calculated, all twice or three times that size. The effect is large, which means that the large objects of a kilometer decrease from every ten thousand years.
While it’s good to give old fashioned rings a good shake every now and then, these newly found rings may not make sense due to their impact.
It could be debris dumped from a strike that was re-excavated in a permanent way. Or they may not be important at all – just a legend in the data.
Garvin can’t believe the debris fields would still be visible after years of erosion and erosion. However, science does not go behind a single evaluation.
It is a hypothesis worthy of debate. As we work to improve systems to avoid a large asteroid strike, chances are good that Earth’s path will become clearer over time.
One thing our world does not need is more scars to hide.
The research was presented at the 2023 Lunar and Planetary Science Conference, held in The Woodlands, north of Houston, Texas.