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PSI joins the world in celebrating Asteroid Day

Painting of Tunguska by Bill Hartman

Tunguska - A Minute After Explosion. © 1997, William Hartmann

Here at PSI, asteroids are baked into a lot of what we do. Literally. Asteroids are both the leftover building blocks of planets and the destroyers of worlds when they crash into one another (or us). As an organization dedicated to understanding our Solar System and beyond, we want to bring your attention to the 2016 UN-sanctioned holiday: Asteroid Day.

Co-founded by Queen guitarist and astrophysicist Brian May, Apollo 9 astronaut Rusty Schweikart, filmmaker Grig Richters, and B612 Foundation president Danica Remy, this event occurs on the June 30 anniversary of the Tunguska Event.

In 1908, a small asteroid or comet exploded over the Eastern Siberian Taiga near the Tunguska River. It is estimated that the energy from the blast flattened more than 2000 square kilometers of forest, and killed 3 people and countless reindeer. Due to the remote location of this event, it was seen by only a few people, most of whom were reindeer herders. The shockwave of the blast, however, literally shook the world and was detected globally. It is estimated that whatever exploded in the atmosphere was between 50-200 meters in size, with different composition objects needing to be larger or smaller to create the observed destruction.

Objects in this range of sizes are pretty common. It’s estimated there should be half a million of them with orbits near our Earth’s orbit… and in many cases crossing our Earth’s orbit. And it’s also estimated that we’ve only been able to discover and track 1% of these objects so far. Put another way, there are basically 500,000 objects out there, unknown, and potentially able to recreate the Tunguska event at any time. (The asteroid that killed the dinosaurs was much larger, 11,000-81,000 meters in diameter, and objects that size are much more rare.)

Earth Approaching Asteroid by Bill Hartmann

Earth Approaching Asteroid © 1994, William Hartmann

While the Tunguska event only killed a handful of people, a similar event over a major city could be devastating. In February 2013, a much smaller 20-meter asteroid exploded over the city of Chelyabinsk, Russia. While no one was killed, nearly 1,500 people were injured, primarily by broken glass. This early morning event caught many people getting breakfast, and when they saw a bright flash from their windows, they looked out to see what was going on. Since sound travels slower than light, this put them directly in harm's way as the sound wave of the explosion burst windows across the city.

PSI researcher Bill Hartmann has done research on both these events. This research, and an opportunity to travel to Tunguska, inspired the artwork you see in this piece. Numerous other researchers here, including our CEO Mark Sykes, have been part of the Dawn Mission to study Vesta and Ceres. Researchers, including Faith Vilas, Deborah Domingue, and others were part of Hayabusa 2’s mission to Ryugu, and the sample site for OSIRIS-REx was in part determined thanks to the Bennu Mapper citizen science project run out of PSI. All these researchers are working to help the human race understand what asteroids are like so we can better understand how to move them if necessary, and utilize them for industry if possible.

PSI is also helping other researchers explore asteroids with the Small Bodies Node of the NASA Planetary Data System. With the web portal, you can explore data from asteroids, collected from multiple nations, and use it to explore new questions.

On this Asteroid Day, we celebrate the tens of people here at PSI, and the hundreds of researchers around the world who have dedicated their careers to studying asteroids and craters, and to helping us build for a future where we can actively avoid going the way of the dinosaurs.

Jun 30, 2021
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