Asteroid impact simulation 2021 ends in disaster

An international exercise to simulate an asteroid hitting Earth has ended. Just six days before a fictitious impact, things don’t look good for an 185km-wide area between Prague and Munich.

Two years ago, the organizers of this event accidentally destroyed New York, and now it’s time for a cross-border region between Germany, Austria and the Czech Republic to suffer the same fate. When I covered the first few days of this week’s simulation on Wednesday, the gathered experts were weighing their options as a 460-foot-wide asteroid was heading towards central Europe.

It might sound like a spooky role-playing game, but it’s a very serious business. Led by NASA’s Jet Propulsion Laboratory Center for Near-Earth Object Studies, asteroid impact simulation is intended to prepare scientists, planners and key decision makers for reality, should it ever happen. The tabletop exercise started last Monday and is taking place almost at IAA 7th Planetary Defense Conference, which is hosted by the UN Office for Outer Space Affairs with assistance from ESA.

“Practice and training for different situations is an important part of preparation, whether by medical professionals, sports teams or artists,” said Andy Rivkin, research astronomer at the Johns Hopkins Applied Physics Lab , in an email. “For planetary defense, this is our chance to bring together people with different expertise who don’t often have the chance to work together and examine different scenarios. This can go a long way in helping identify important issues that we might not identify when working in small groups or as individuals. “

Rivkin, who attended the event, is the co-leader of NASA’s Double Asteroid Redirection Test, which aims to crash a spaceship in the asteroid Dimorphos at the end of 2022 (for real). By hitting an asteroid, a kinetic impactor like DART can “change the asteroid’s arrival time so that it doesn’t arrive at the crossroads at the same time as Earth,” Rivkin said, adding that his group was testing this. which “happens in detail when you change the speed of an asteroid”, in this case Dimorphos.

A distinguishing feature of this year’s simulation is that the asteroid came out of the blue, so to speak. Called “PDC 2021”, it was discovered just six months before its scheduled meeting with Earth. The probability of an impact was initially rated at 1 in 2,500, but was increased to 1 in 100 during the first day of the simulation. On day 2, the odds were increased to 100% with the impact site identified as being in Central Europe.

For me, one of the main lessons from this year’s simulation was the dramatic way in which key variables, such as the area of ​​likely impact and the size of the affected population, were affected by the new observations. At one point, for example, North Africa, the UK and much of Scandinavia were inside the possible strike zone.

Simulation participants found it impossible to deploy a mitigation effort, such as a kinetic impactor or a nuclear bomb, given the short time frame – a consideration that did not escape planetary geologist Angela Stickle, another member of the DART team who participated in the exercise.

“The timeline of the deviation is important,” Stickle, head of the DART Impact Modeling Working Group, explained in an email. “Kinetic impactors work best when done years in advance, so the little push you give has enough time to really change the incoming orbit away from Earth, so even though we could have launched a spacecraft spatial kinetic impactor like DART on the exercise scenario table, we might have been too late to really deviate from its trajectory. ”

Previous tabletop exercises provided many years of warning time, but this one did not. Accordingly, the focus of the exercise was on disaster response and the importance of identifying dangerous asteroids in advance.

For Andy Cheng, chief scientist and co-head of the DART investigative team at Johns Hopkins, the auspicious moment for learning came when they all learned that the fictional asteroid had in fact passed Earth seven years earlier. , but it was not discovered “because there was no land.” – or space telescopic assets in place which would have discovered it, ”he explains in an email. If it had been detected at the time, “there would have been an alert time more than sufficient to mount space missions to characterize it and mitigate the threat”, as with a DART type mission.

As a result, tabletop simulation became an exercise in predicting the possible damage that could be inflicted by the asteroid and where that damage could occur. It was not an easy task, given many uncertainties about the offending object, such as its size and physical makeup. Initial estimates place the asteroid between 115 feet (35 m) and 2300 feet (700 m) in length, followed by a more precise estimate of 460 feet (140 m), which “dramatically reduces the size of the worst case and the worst correspondent. case of impact energies, ”according to the Day 3 report.

Which brings us to the last day of the exercise (it turns out this was a four day project, not five days as was originally reported). Day 4 will take place on October 14, 2021, just six days before impact. With the impact now imminent onere the fake asteroid clearly in sight, the terrible situation became clear.

The fictitious impact would occur on October 20, 2021 at 17:02:25 UTC, in one second. This level of precision is truly fascinating and demonstrates how prepared we would be for this fateful moment, allowing residents of the affected and surrounding areas to evacuate or take cover.

Images taken by Goldstone Observatory the day before limited the size of the asteroid to 105 m (345 feet) in diameter. It wasn’t as big as feared, but still big enough to cause serious damage. For Mallory DeCoster, a systems and mechanical engineer and a member of the Johns Hopkins DART investigation team who also participated in the exercise, the lingering uncertainty about the asteroid’s size proved troublesome.

“We know that one of the most important information for decision makers is high fidelity information about the size of the asteroid,” she said. “In the hypothetical impact scenario, we saw that the current capabilities of the instruments left us with a fairly wide range of possible sizes for the asteroid, ranging from a low threat diameter of 30m to an exploding diameter on the continent of 700 m. This showed how important it is to invest in instruments such as ground-based radars and space infrared sensors to provide high-resolution characterization measurements. “

The false asteroid was expected to strike Earth at speeds of up to 9.5 miles per second (15 km / s), or 34,000 miles per hour (55,000 km / h). Ground Zero was predicted to reside within a 23 km radius, but that number is expected to halve in the coming days as the asteroid nears. The impact site was centered near the borders of three countries: Germany, the Czech Republic and Austria.

This area is predominantly rural and no estimate has been given on the size of the affected population. In the worst case scenario, the asteroid would inflict damage extending 150 km in all directions. A threat map indicated areas designated as insurvable, critical, severe, and severe. Prague, a city of 1.27 million people, resides on the outer border of the grave area, while Munich seemed out of danger.

If this had been real, the International Asteroid Warning Network – a group that detects, tracks and characterizes potentially dangerous asteroids – would have disseminated this information in accordance with a United Nations General Assembly resolution, according to the report. ‘today. This would be done to “ensure that all countries … are aware of potential threats”, and to emphasize the need to develop “effective emergency response and disaster management in the event of an object impact. close to Earth ”, according to the resolution.

Stickle said several things stood out about this year’s exercise, including the importance of clear public communication, especially in providing information to people about the threat and what can be done to prevent it. impacts on Earth.

“I think DART can be a good addition to this as an example of how we prepare and test the necessary technology; the mission provides a good opportunity for public communication and engagement, ”Stickle wrote. “The exercise also demonstrated the importance of being able to rapidly deploy kinetic impactors in an emergency scenario.” That said, she described the six-month schedule as “sporty enough” as they should act really fast, even with a mitigation solution out of the box.

Mallory DeCoster, systems and mechanical engineer and member of the DART investigation team also responded, saying that we “really need to find and track more asteroids”, adding that this is not surprising, “but this short warning scenario clearly highlights the importance. of that. “

And with that, the roundtable was over, as it really only remained to wait for the asteroid to strike. This is all very morbid, but this year’s simulation proved to be useful. Hopefully these exercises will continue to remain in the realm of fiction.