Bracing for Imminent Impact with Michael Frazer
Something in the Air
I waltz into Mallokup, an open-air café nestled in the science and technology precinct on Curtin University campus. The air suffocates me, thick with spring spores that cling to every breath. My eyes scan the scene and settle on a solitary figure. Michael spots me from across the courtyard and waves me over. We soon anchor our intense conversation—asteroids, meteorites and the cosmos—beneath a canopy of whispering leaves.
Flying Rocks
Imminent: {adjective} about to happen.
Impactor: {noun} [astronomy] an object, such as a meteorite, which collides with another body.
‘The impactor we’re talking about is a rock in space impacting the Earth.’ Meteors only become meteors when they interact with Earth’s atmosphere; before that, they are classified as either asteroids or meteoroids. When meteors are bright enough, we call them fireballs. When fireballs reach the ground, they might be recovered as a meteorite, although a lot of the time they explode on impact. ‘We see about one of these fireballs over Australia every night, which is quite a lot.’
The impactor we’re talking about is a rock in space impacting the Earth.
Imminent impactors are what asteroids and meteoroids are called before they strike Earth. Michael studies these imminent impactors, figuring out where they come from and where they’re going, using both optical and radio telescopes. Seeing an imminent impactor before they hit Earth is quite rare.
Watching and Waiting
‘I’m currently working with data from the Vera C. Rubin Observatory, in Chile. That’s a telescope being built by a whole bunch of U.S. and international consortiums that we have data access to.’ The Vera C Rubin Observatory houses the Simonyi Survey Telescope optical telescope with a mirror of over 8 metres in diameter. It has a Legacy Survey of Space and Time (LSST) camera which allows wide-field imaging, high-resolution photos with a 3200-megapixel camera, multispectral imaging, time domain imaging and data generation reaching over 10 terabytes of data per night. This is a game changer for PhD candidates and researchers alike who depend on timely and accurate data to analyse information concerning imminent impactors. ‘You’re looking at objects that are so far away that you need huge telescope instruments to see any light from them. When you do get whatever type of data that you’re working with, you must be able to get so much information out of such a small amount of data.’
The telescope being built at the Vera C Rubin observatory is a new commission. Previously, planetary scientists have disseminated data from the larger optical telescopes mostly parked in the Northern Hemisphere. ‘There’s a few telescopes ATLAS, Pan-STARRS and the Catalina Sky Survey are three big telescopes all around the world. A big part of why they exist is to sweep the sky quickly every night and spot objects or imminent impactors that are going to potentially hit the Earth.’ ATLAS is a telescope funded by NASA and developed by the University of Hawaii and is an asteroid impact early warning system. Pan-STARRS is a telescope operated by the Institute for Astronomy and focuses on Near Earth Objects. Found in Arizona, the Catalina Sky Survey is part of the Near-Earth Object Observation (NEOO) program, also funded by NASA.
‘Rocks that are bigger than about 140 metres and might hit the earth are what we call potentially hazardous asteroids.’ The Planetary Defense Coordination Office (PDCO), founded in 2016, was designed to facilitate NASA’s mission of finding and tracking asteroids and comets to better understand their potential hazard potential to Earth. Part of planetary defense involves deflection or destruction of the Near-Earth Object.
Seeing is Believing
‘In 11 cases, optical telescopes, such as ATLAS, Pan-STARRS and Catalina, have seen rocks that have then hit us. These rocks have all been pretty small. I think the largest was about three or four metres across. They mostly burn up at 30-kilometres altitude in the atmosphere and cause no damage, but a few have made it to the ground as meteorites.’ The point of looking for imminent impactors close to Earth is to be able to look deeper into space. When scientists can look into the depths of space for larger objects on a collision course for Earth, they can navigate how to avoid the object, which is less about dodging and more about pushing and breaking.
On June 30, 1908, in Tunguska, Siberia an asteroid, 50-100 metres long, seared through the skies and exploded. The energy payload was about 15 megatonnes worth of TNT. It ignited a huge forest fire and flattened trees for many kilometres. In Chelyabinsk, Russia on 15 February, 2013, a meteorite that was 20 metres long exploded at an altitude of 30 km. This was caught on dashcams. Its energy payload was 500 kilotonnes of TNT. This is 30 times more powerful than the atomic bomb deposited in Hiroshima at the end of World War II. The meteorite damaged over 7200 buildings and sent more than 1500 people to hospital due to the shockwave. Even small meteorites have the potential to cause damage when they fly into Earth.
Warning, Warning!
‘Some of the asteroids that we’re talking about come between us and the moon. We define our potentially hazardous asteroids if they come within a certain distance from us. With our current telescopes, there’s on average been a nine-hour warning.’ Sometimes the warning is a bit longer, but it has so far always been under 24 hours. In fact, the average asteroid sprints along at about 11 km/s,. At that speed, an asteroid could cross the UK in under a minute—faster than a commercial jet crosses a city. By the time astronomers have seen the asteroid, it has already moved due to a small delay from the travel of light.
Complex Calculations
‘Once you’ve got at least three observations, either from the same observatory or from separate ones, we can measure the right ascension (astronomical longitude), declination (astronomical latitude) and the rate of motion across the sky. From there, we can begin to fit an orbit and calculate the trajectory and where it might impact/land.’
Another calculation used in mapping where the objects are, is Earth’s bulge. Earth is not round. Due to the rotation, Earth bulges outwards at the equator, as do all planets and even the Sun. ‘When we started using telescopes or talking with telescopes who weren’t reporting their altitudes very well, that was a problem. We had to write to these telescopes and say, hey, what exactly is your altitude? You’ve just said two kilometres above sea level. But is that above sea level or above the average surface of the Earth? Three or four metres makes a difference when we’re doing small geometry’ Once observatories clarified position, data was easier to extract, making Michael’s and other scientists’ jobs much easier when it comes to calculating the trajectory of imminent impactors.
That’s what science, and astronomy in particular, is all about— asking “I wonder if we can do this?”
Resulting Results
‘To improve our measurements, we need more observations, so we can ask other observations to collect more observations Then we can say, yes, that’s going to hit us, likely going to hit us, or not hit us at all.’ Working together, with planetary scientists, astronomers and astrophysicists, in both optical and radio observatories, the students and experts calculate trajectories, speed, mass and possible composition of these flying rocks from space. When armed with the right data, policy makers and planetary defence organisations can make the call on what to do about hazardous impactors before they arrive to cause widespread damage and chaos.
Pollen coats our table. A gaggle of students arrive on the stage. A plane’s engine roars above our heads. Michael finishes leaving me with this profound thought. ‘That’s what science, and astronomy in particular, is all about— asking “I wonder if we can do this?” Let’s just try and see if we can. A lot of the time you can’t. But that’s OK, because it’s the few times that you can that are exciting and make it all worth it.’
Written by Louise Kaestner, 2025. For more, visit LinkedIn or head to her website: https://www.louisekaestnerwriter.com/