Asteroids permeate the Solar System, and thousands of these bodies are known to pass close to our own planet. Most of these bodies are small, and the Earth is regularly bombarded by 100 tons of material from space every day, burning up harmlessly in the atmosphere. However, the danger from a larger body is real, with an impact potentially wiping out cities, nations, or causing a worldwide extinction.
For two decades, NASA and other space agencies have been scouring the skies, searching for asteroids and comets which may impact the Earth. Now, the American space agency and FEMA are carrying out simulations to determine how prepared we would be if a large asteroid were to impact our world. Between April 29 and May 3, 2019, a tabletop exercise will be conducted at the sixth annual conference on planetary defense, hosted by the International Academy of Astronautics (IAA).
“These exercises have really helped us in the planetary defense community to understand what our colleagues on the disaster management side need to know. This exercise will help us develop more effective communications with each other and with our governments,” Lindley Johnson, NASA’s Planetary Defense Officer, said.
As part of the exercise, the agencies have created data for a fictional asteroid, designated 2019 PDC (even this designation is not valid for a real asteroid). In this fictional scenario, 2019 PDC was discovered March 26, 2019, and the object is deemed to be a Potentially Hazardous Asteroid (PHA).
Computer simulations predict the most likely date for impact is April 29, 2027 — eight years after discovery. The probability of impact is initially deemed to be fairly low — just one in 50,000. As observations continue, the chances of the asteroid hitting Earth rise — reaching one percent on the first day of the real-world meeting. The exercise runs through scenarios of how humans might respond to such a threat, were such an asteroid found heading our way.
This Sounds Like Rock and/or Roll…
Near-Earth Objects (NEO’s) are bodies passing within both 195 million kilometers (121 million miles) of the Sun and 50 million kilometers (30 million miles) of Earth. Fortunately, most of these objects are small enough (less than 20 meters, or 66 feet in diameter) that they would burn up in the atmosphere, were they to encounter Earth. Astronomers currently know of more than 18,000 NEO’s, and are still discovering roughly 40 of these objects every week. Although no such body is currently known to be on a collision course with Earth, a few remain a concern to observers.
“Noteworthy among these is 99942 Apophis, one of the most important near-Earth asteroids ever discovered. This asteroid will pass by Earth on Friday, April 13, 2029, closer than where our weather satellites orbit. It will be bright enough to be visible with an unaided eye for several hours around the closest approach. Apophis, named after the ancient Egyptian spirit of evil, darkness and destruction, is estimated to be around 340 meters in diameter and if it were to hit, it would cause major damage to our planet and likely to our civilization as well,” the IAA reports.
Because asteroids are so small, and usually dark, they are difficult to spot until the object is just a few hours or days away from crossing the orbit of the Earth. Quite often, media outlets drive flurries of reports on these near-misses, which occur on a fairly regular basis.
Sorry… False Alarm
On March 11, 1998, a message was sent to astronomers worldwide who search for asteroids, announcing that a body discovered the previous year, 1997 XF11, might strike the Earth in 2028. That message was soon picked up by the media and the general public, feeding popular stories of a one-kilometer (half-mile) wide object hitting the planet in just a few years. Subsequent observations showed the Earth is in no danger from XF 11, but that idea still remains in the minds of many people.
“To this day we still get queries on the chances of XF11 impacting in 2028. There is simply no chance of XF11 impacting our planet that year, or for the next 200 years,” said Paul Chodas, director of NASA’s Center for Near-Earth Object Studies (CNEOS) at Jet Propulsion Laboratory.
On March 15, 2019, a large asteroid exploded in the air above the Krasnoyarsk region of Russia. As the object heated, it divided into at least two pieces before exploding with a force estimated by some observers to be around 185 times greater than the atomic bomb that destroyed the city of Hiroshima at the end of the Second World War. At least one piece of that body crashed through a meter of ice, landing in the Podkamennaya Tunguska river.
A Game of Interplanetary Dodgeball
In 1998, Congress directed the nation’s space agencies to find and track 90 percent of near-Earth asteroids larger than one kilometer (3,280 feet in diameter) within 10 years. With that goal accomplished, asteroid hunters now have plans to discover and track 90 percent of all such bodies 140 meters (450 feet) across by the year 2020. Asteroids of this size would not cause a worldwide catastrophe were they to strike the planet, but an impact close to a metropolitan area could still result in significant damage and loss of life.
Russia seems to attract more than its fair share of asteroids and cometary impacts, due to the massive size of that nation. In 1908, a large asteroid or comet exploded in the atmosphere near Stony Tunguska River in Yeniseysk Governorate (now Krasnoyarsk Krai), Russia, sending trees down over a wide area, in an event known as the Tunguska event. In February 2013, the country was the victim of another visitor from space, as an asteroid exploded above Chelyabinsk, injuring more than 1,100 people.
As astronomers discover more NEO’s, we gain more knowledge about which bodies pose a risk to our planet. However, the search will not be complete for the foreseeable future, and it only takes a single body to wreak havoc with human populations.
I Love You, You Love… BOOM! Sorry, Barney!
Should we find a dangerous object headed our way, the more time we have, the better it will be for those charged with heading off an impact. Despite what is seen in many science fiction stories, blowing up an asteroid would only turn a bullet into a shotgun blast, distributing the damage over a wider area. Given enough time, the safest course of action would be to alter the orbit of the body, causing it to miss the Earth.
“I don’t want to be the embarrassment of the galaxy to have had the power to deflect an asteroid, and then not and end up going extinct. We’d be the laughingstock of the aliens of the cosmos if that were the case.” — Neil deGrasse Tyson
Roughly 66 million years ago, an asteroid the size of Mount Everest impacted the Earth, setting off a chain of environmental consequences, ending the age of the dinosaurs.
Unlike those unfortunate animals, humans have the ability to see an asteroid headed our way, if we put a determined effort into searching for them. But, we are just starting our search for these bodies, and it remains a daunting challenge to find the next doomsday rock before it finds us.