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Huge region of Europe destroyed by asteroid effect in planetary defense exercise

Fictitious asteroid impact zone

The shaded areas in this image show where (fictional) impact is most likely to occur. There is a 99% chance that the impact will be located within the outer contour, 87% within the middle contour and 40% within the central dark red region. For educational purposes only. Not really. Credit: ESA

In an alternate reality played out at this year’s international planetary defense conference, a fictitious asteroid crashes over Europe and ‘destroys’ a region about 100 km wide near the Czech Republic and the German border. The scenario was imagined, but the people who participated are very genuine, and the lessons learned will shape our ability to respond to dangerous asteroids in the years to come.

Asteroid impact: the only natural disaster we might prevent

Natural hazards come in a variety of forms and occur with varying frequency. Some are relatively frequent events with local influences such as floods and forest fires. Others occur only once in a blue moon, but can affect the entire planet, such as global pandemics and asteroid effects.

However, the threat from asteroids is unique: an asteroid effect is the most predictable natural disaster we face, and given sufficient warning, we have in principle the technology to completely prevent it.

Hera network with CubeSats

ESA’s Hera Mission to Didymo’s binary asteroid system will carry two CubeSat Opportunity payloads (COPINS) – named Juventas and Milani – to support the scientific objectives of the main spacecraft as well as demonstrate deep space-inter-satellite connection techniques. Credit: ESA – ScienceOffice.org

Over the last few decades, the field of planetary defense has made remarkable progress – humans now have telescopes scattered all over the planet searching for dangerous spaceships, the largest of which have all been discovered, and this year we are launching a mission that will set for the first time asteroid bending on trial.

The good news is that when it comes to giant dinosaur-sized asteroids, we’re pretty sure we’ve found everyone out there. Due to their large size, they are easy to spot. But the smaller they become, the more we still have to find out why the impact of this year’s asteroid, 2021 PDC, provided such an important lesson: we can only prevent what we can predict.

This year’s scenario: mission impossible

Although this scenario is realistic in many ways, it is completely fictional and
does NOT describe an actual asteroid effect.

It all began on April 19, 2021, when a new asteroid was discovered by the Pan-STARRS near-Earth object exploration project. It quickly became clear that this asteroid was likely to hit Earth in just six months.

Further observations confirmed what the international community had feared an impact was certain. However, the size of the object remained unclear and ranged from 35 to 700 meters in diameter.

As would be the case if a real asteroid were on a collision course, the International Asteroid Warning Network (IAWN) – a network of organizations that detect, track and characterize potentially dangerous asteroids – publicly provided weekly updates on the likelihood of impact as the situation progressed.

At the same time, the Space Missions Planning Advisory Group (SMPAG) began to consider our options for preventing the impact. But time is short and we are still unsure of the size of the object. Most options for deflecting an asteroid – such as deflection via a high-energy impact, ‘gravity tractor’ or ‘ion beam shepherd’ – work by simply pushing the targeted space rock lightly. But if performed far enough in advance, the small initial push builds up to become a major shift in position when the asteroid gets close to Earth.

On day three of the conference, the scenario leaps forward two months to June 30, less than four months, until the imaginary asteroid would hit. At this point, SMPAG concludes that no space missions can be launched in time to deflect or disrupt the 2021 PDC from its collision course.

Experiences: we cannot prevent what we cannot predict

A scenario like this, where an asteroid effect is predicted with a short warning in just a few months, poses challenges for prevention in space.

Asteroids in our solar system do not appear out of nowhere, they travel in orbit around the sun for thousands, millions of years. Like annual meteor showers, we can calculate with great certainty when an asteroid will be back.

Had a more sensitive asteroid study like NEOSM or the Rubin Observatory (LSST) been in place in 2014, they would almost certainly have discovered the 2021 PDC on an earlier journey around the sun, and this seven-year warning would have opened up a host of different possible results. In particular, space missions would have been possible for a reconnaissance mission to find out more about the size and composition of the asteroid, or a simple ‘kinetic-impactor’ deflection mission could have pushed it out of the way.

Investment in the eyes of heaven

Telescopes and surveys such as the PanSTARRS or Catalina survey and many more are discovering new near-Earth objects (NEOs) every day. ESA is adding this global network with its upcoming network of high-tech ‘Flyeyes’.

ESA’s Test-Bed Telescope, the second of which was recently installed at La Silla in South America, is a collaborative project with TO effectively performing follow-up observations of NEOs, and the first Flyeye telescope is currently under construction to be installed on a mountain top in Sicily, Italy, with an insect-inspired design that allows large areas of the sky to be covered much faster than traditional designs.

Investments like these as well as those that are underway across the globe are fundamental to protecting us from dangerous asteroids. We have to find them before we can do anything about them.

Lessons from COVID-19

“It’s not good enough to think in annual or semi-annual planning cycles, which are how many budgets at public institutions are set, to counter a risk that has been going on for hundreds of millions of years.”

This year’s conference, like most events in recent months, took place entirely online. As many participants noted, the preparation for a disaster while in the middle of another had a unique impression, a not so subtle reminder that unlikely but catastrophic events are very real and need to be prepared for.

Disaster management experts, local governments, mission planners, and policy experts regularly look at past events to see what worked and what went wrong. On the fourth day of the conference, lessons from past disasters such as hurricanes, floods and earthquakes were discussed along with lessons from COVID-19 pandemic.

Of crucial importance is the need to invest in research and technology, prepare governments and local authorities, including with realistic training scenarios, understand how to protect different populations with different needs, including the most vulnerable in society, and provide clear and transparent information and advice to public.

“A big lesson was that we need more long-term planning of how we can spot, track and ultimately mitigate potentially dangerous asteroids,” said Detlef Koschny, head of ESA’s Planetary Defense Office.

“It’s not good enough to think in annual or semi-annual planning cycles, which are how many budgets at public institutions are set, to counter a risk that has been going on for hundreds of millions of years.”

Finally, one thing is clear: an asteroid effect, though unlikely, is likely to happen sooner or later – so it’s best to be prepared.

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