Scientists around the world were embarrassed this week by a fictional asteroid heading for Earth.
A group of experts from US and European space agencies participated in a week-long exercise led by NASA in which they were confronted with a hypothetical scenario: an asteroid 35 million kilometers away was approaching the planet and could strike within six months.
With each passing day of exercise, participants learned more about the asteroid’s size, path and chances of impact. Then they had to cooperate and use their technological knowledge to see if anything could be done to stop the space rock.
The experts failed. The group determined that none of Earth’s existing technologies could prevent the hypothetical asteroid from hitting given the simulation’s six-month delay. In this alternate reality, the asteroid crashed in Eastern Europe.
To our knowledge, no asteroid currently poses a threat to Earth in this way. But it is estimated that two-thirds of asteroids 460 feet or larger – large enough to cause considerable havoc – stay unknown. This is 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 that we are all coordinated if a potential impact threat is identified in the future,” Lindley Johnson, head of the NASA planetary defense, said in a press release.
6 months is not enough time to prepare for an asteroid impact
The fictional asteroid in the simulation was called 2021PDC. In the NASA scenario, it was first “spotted” on April 19, and after a week, scientists were able to calculate that it had reached 5% of our planet on October 20, six months after its date. of discovery.
But the second day of the exercise unfolded quickly to May 2, when new impact trajectory calculations showed that PDC 2021 would almost certainly hit Europe or North Africa. Participants in the simulation envisioned various missions in which spacecraft might try to destroy the asteroid or divert it from its path.
But they concluded that such missions could not take off in the short time before the asteroid impact.
“If we were faced with the hypothetical scenario of PDC 2021 in real life, we would not be able to launch a spacecraft in such a short time frame with current capabilities.” the participants said.
They also considered trying to detonate or disrupt the asteroid using a nuclear explosive device.
“Deploying a nuclear disruption mission could significantly reduce the risk of impact damage,” they noted.
Nonetheless, the simulation stipulated that 2021PDC could be between 114 feet and half a mile in size, so the likelihood that a nuclear weapon could breach was uncertain.
Day 3 of the exercise took place on June 30 and the future of Earth looked grim: the impact trajectory of PDC 2021 showed it was heading towards Eastern Europe. By day 4, which advanced rapidly to a week before the asteroid impact, there was a 99% chance that the asteroid would strike 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 areas in advance.
Most asteroids fly under the radar and many are spotted too late
It’s tempting to assume that in the real world, astronomers would spot a 2021PDC-like asteroid on much longer than six months’ notice. But the world’s ability to monitor Near-Earth Objects (NEO) is sadly incomplete.
Any rock in space with an orbit that takes it within 125 million kilometers of the sun is considered an NEO. But Johnson said in July that NASA believed “we’ve only found about a third of the asteroid population that could pose a risk of impact on Earth.”
Of course, humanity is hoping to avoid a surprise like that of the dinosaurs 65 million years ago, when a 10 km wide asteroid crashed into Earth. But in recent years, scientists have missed many large, dangerous objects that have come close.
Comet Neowise, a 3-mile-wide piece of space ice, passed within 64 million miles of Earth in July. No one knew this comet existed until a NASA space telescope discovered it four months ago.
In 2013, a meteor approximately 65 feet in diameter entered the atmosphere at a speed of 40,000 mph. 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 within 45,000 miles of Earth. NASA had almost no warning about it.
Indeed, currently the only way scientists can track an NEO is to point one of Earth’s many powerful telescopes in the right direction at the right time.
To solve this problem, NASA announced two years ago that it would launch a new space telescope dedicated to monitoring dangerous asteroids. This telescope, called the Near-Earth Object Monitoring Mission, as well as the new launch of the European Space Agency Test bench telescope and the Flyeye Telescope which is under construction in Italy, should eventually increase the number of NEOs that we can follow.
NASA is testing ways to thwart an asteroid
NASA investigated the options scientists would have if they found a dangerous asteroid on a collision course with Earth. These include detonating an explosive device near space rock, as exercise participants suggested, or firing lasers that could heat and vaporize the asteroid enough to change its course.
Another possibility is to send a spacecraft to crash into an oncoming asteroid, knocking it out of its path. This is NASA’s most serious strategy: later this year, the agency is expected to launch a test of such technology. The Double Asteroid Redirection Test (DART) will send a spacecraft to the asteroid Dimorphos and deliberately strike it in the fall of 2022.
NASA hopes the collision will change Dimorphos’ orbit. While this asteroid is not a threat to Earth, the mission could prove that redirection of an asteroid is possible with sufficient time.