Space agencies around the world took part in a simulation of an asteroid collision scenario. The experts involved learned the trajectory of the fictional asteroid and had to react. During the exercise, they failed to prevent the asteroid from hitting Europe, showing how unprepared we are for such a crisis.
A group of experts from American and European space agencies took part in a week-long exercise led by NASA in which they faced a hypothetical scenario: An asteroid 35 million miles away is approaching the planet and could collide with it within six months.
With each day of the exercise, participants learned more about the asteroid’s size, trajectory, and probability of impact. Then they had to collaborate and use their technological knowledge to see if anything could be done to stop the space rock.
The team determined that no existing technology on Earth could stop a hypothetical asteroid impact within the six months of the simulation. In this alternate reality, the asteroid crashed into Eastern Europe.
As far as we know, no asteroid currently poses such a threat to Earth. But about two-thirds of asteroids 460 feet or larger — large enough to wreak considerable havoc — go undetected. That’s why NASA and other agencies are trying to prepare for such a situation.
“These exercises ultimately help the planetary defense community communicate with each other and with our governments to ensure coordination if a potential collision threat is detected in the future,” said Lindley Johnson, NASA’s planetary defense chief.
Six months is not enough time to prepare for asteroid impact
The fictional asteroid in the simulation was called 2021PDC. According to NASA’s scenario, it was first “spotted” on April 19 and was thought to have a 5% chance of colliding with our planet on October 20, six months after it was discovered.
But the second day of the exercise was pushed back to May 2 when new collision trajectory calculations showed that 2021PDC would almost certainly hit either Europe or northern Africa. Simulation participants considered various missions in which spacecraft could try to destroy the asteroid or deflect it from its trajectory.
But they concluded that such missions would not be able to launch in the short time before colliding with the asteroid.
“If we were faced with a hypothetical 2021PDC scenario in real life, we would not be able to launch any spacecraft in such a short time with current capabilities,” the participants said.
They also considered detonating or destroying an asteroid with a nuclear explosive device.
“Deploying a nuclear demolition mission could significantly reduce the risk of collision damage,” they concluded.
However, according to the simulations, 2021PDC could range in size from 114 feet to half a mile, so the likelihood that a nuclear bomb could do damage was uncertain.
The third day of the exercise was rescheduled for June 30, and Earth’s future looked bleak, with 2021PDC’s impact trajectory showing it headed for Eastern Europe.
By the fourth day, which had been postponed a week before the asteroid impact, there was a 99% chance that the asteroid would fall near the border between Germany, the Czech Republic, and Austria. The explosion would bring as much energy as a large nuclear bomb.
All that could be done was to evacuate the affected regions in advance.
It is tempting to assume that in the real world, astronomers would spot an asteroid like 2021PDC much earlier than six months, but we cannot detect most asteroids at all, and many are spotted too late.
Any space rock orbiting within 125 million miles of the Sun is considered dangerous However, according to NASA, “we have detected only a third of all asteroids that could pose a danger to Earth.”
Of course, humanity hopes to avoid a surprise like the one 65 million years ago for the dinosaurs, when a 6-mile-wide asteroid crashed into Earth. But in recent years, scientists have missed many large and dangerous objects that have come close to Earth.
Comet Neovise, a 3-mile-wide chunk of space ice, passed 64 million miles from Earth in July. No one knew this comet existed until a NASA space telescope detected its approach four months earlier.
In 2013, a meteor about 65 feet in diameter entered the atmosphere at 40,000 miles per hour. It exploded over Chelyabinsk, Russia, without warning, sending a shock wave that shattered windows and damaged buildings across the region. More than 1,400 people were injured.
And in 2019, a 427-foot-wide “city killer” asteroid flew 45,000 miles from Earth. NASA didn’t even know about it.
That’s because scientists can currently track asteroids only by pointing one of Earth’s limited number of powerful telescopes in the right direction at the right time.
To solve this problem, NASA announced two years ago the launch of a new space telescope designed to watch for dangerous asteroids. The telescope, called the Near-Earth Object Surveillance Mission, along with the European Space Agency’s recently launched Test-Bed Telescope and the Flyeye Telescope being built in Italy, should eventually increase the number of asteroids we can track.
NASA has explored options for scientists in the event that a dangerous asteroid is detected on its way to collide with Earth. These include detonating an explosive device near the space rock, as suggested by the exercise, or launching lasers that could heat and vaporize the asteroid enough to change its trajectory.
Another possibility is to send the spacecraft upward to crash into an oncoming asteroid, thereby knocking it off its trajectory. This is the strategy that NASA takes most seriously: the agency plans to launch a test of such technology later this year. The Double Asteroid Redirection Test (DART) project will send the spacecraft toward the asteroid Dimorphos in the fall of 2022 and purposefully crash into it.
NASA hopes that the collision will change the orbit of Dimorphos. Although this asteroid does not pose a threat to Earth, the mission may prove that redirecting the asteroid is possible with enough time.