Chances of this asteroid hitting Earth are tiny – but not zero
It’s not the plot of another doomsday movie. Yet there is a pending, albeit unlikely threat to life as we know it: an asteroid approaching Earth.
Bennu, a rugged, rock-spewing asteroid with a diameter of about one-third of a mile (half a kilometre), is headed in our direction, on track to come very close with Earth in September of 2135.
But not to panic, scientists with NASA said Wednesday. Though Bennu will come within half the distance of the moon, the odds of the asteroid colliding with Earth in the next century and causing Armageddon-type of destruction are still very low.
“Even though there is no possibility whatsoever of in impact during that encounter, Bennu is going to be fairly close to the Earth,” said Davide Farnocchia, a scientist with the Center for Near Earth Object Studies, a NASA centre that calculates asteroid and comet orbits and their odds of impact at the Jet Propulsion Laboratory in Southern California
Although researchers believe it will not impact Earth, they now face the challenge of deciphering how our planet’s gravity will alter the asteroid’s path around the sun, NASA scientists said in a conference call with reporters Wednesday.
Scientists noted there is small possibility that the asteroid could pass through what’s known as a “gravitational keyhole” that could potentially put it in en route to Earth at a later date in the 22nd century.
A gravitational keyhole is a tiny region in space where a planet’s gravity can tweak the trajectory of a passing asteroid and put it on a path to collide with it in the future.
Farnocchia said that although recent findings show the odds of impact have slightly increased — from 1-in-2,700 to 1-in-1,750 over the next century — it “does not represent significant change,” or a reason to worry.
Farnocchia explained that scientists now have a much better idea of Bennu’s path thanks to data collected by NASA’S Origins, Spectral Interpretation, Resource Identification, Security-regolith Explorer (OSIRIS-REX) spacecraft, which orbited and studied the asteroid for over two years.
“Overall the situation has improved,” Farnocchia, the lead author of a study published Wednesday, told reporters in a conference call. “I am not any more concerned about Bennu than I was before; the impact probability remains very small.”
In the study, NASA researchers used precision-tracking data from the OSIRIS-REX spacecraft to better understand Bennu’s movements through 2300, improving scientists’ ability to determine the probability of impacting Earth and predict the orbits of other asteroids.
Using NASA’S Deep Space Network of giant radio antennas that support interplanetary spacecraft missions and computer models, scientists were able to determine Bennu’s overall probability of striking is about 1 in 1750 (or 0.057 per cent.)
Looking at it from glasshalf-full perspective, it means there is a 99.94 per cent probability that Bennu will not hit our planet.
Scientists also calculated the day with the highest risk of collision: Sept. 24, 2182, with a probability of 1 in 2,700 (or about 0.037 per cent) — which is still lower that the overall probability of impact through 2300.
The potentially hazardous asteroid was discovered in 1999 by the Lincoln Nearearth Asteroid Research Team, a program that works on detection and tracking, and has been closely observed with 580 ground-based “astrometric observations,” mainly made by optical and radar telescopes through 2018, according to the study published in Icarus Journal.
Since its discovery, Bennu has had three close encounters with Earth, in 1999, 2005 and 2011, during which two radar stations collected data of the asteroid’s measurements.
Although the chances of it colliding with Earth are very low, Bennu remains one of the two most hazardous known asteroids in our solar system, along with another called 1950 DA, NASA said in a news release. Researchers stated that the most pressing threat for Earth from space objects are hazardous asteroids that are undetected.