There’s a giant asteroid called Bennu hurtling through space that scientists estimate will likely one day slam into the Earth, causing all kinds of devastation and calamity. And although astronomers and physicists do not believe Bennu is large enough to be a planet killer, it certainly is in the range of a city killer, and a large city at that. NASA has plans for a spacecraft to head out and explore the giant asteroid. But shouldn’t NASA — and the rest of the world — be more worried? And why is it that there isn’t more urgency in the idea of redirecting the giant asteroid?
The main reason why there doesn’t seem to be a sense of panic or urgency in response to the idea of a massive killer asteroid bearing down on planet Earth is that, as Space.com points out, by most models and estimates, Bennu wont’ actually slam into the Earth for about 150 years. That is, if it slams into the Earth at all.
You see, Bennu’s solar swing brings it inside Earth’s orbit every six years — it will even pass between the orbit of Earth and the Moon in 2135 — and, with each passing, has its orbital path affected by the gravitational pull of the bodies it passes. So, until Bennu actually accomplishes its near-Earth (and near-Lunar) pass that will allow scientists to better calculate its subsequent orbital trajectory, the best estimates suggest that the giant asteroid will collide with the Earth in the 22nd century.
Even so, Bennu, which is classified as a Potentially Hazardous Asteroid (PHA) by NASA’s space object-tracking Near Earth Object Program, is 1,650 feet wide (500 meters) and is not a planet killer. Its destructive capacity could possibly be catastrophic, even extinction event level, but the extent of impact damage is dependent upon any number of factors ranging from where it impacts the Earth to its velocity upon impact and the actual composition of the space rock itself. And the potential damage could be further limited by what NASA’s OSIRIS-REx spacecraft uncovers when it arrives to explore the asteroid.
Regardless, Dr. Dante Lauretta, OSIRIS-REx’s principal investigator and professor of planetary science at the University of Arizona’s Lunar and Planetary Laboratory, told Space.com there was no need to worry about Bennu destroying the Earth.
“We’re not talking about an asteroid that could destroy the Earth. We’re not anywhere near that kind of energy for an impact.”
Lauretta told the Sunday Times a couple days earlier that the 2135 near-Earth pass was what will alter the asteroid’s course and send it on its way to eventually collide with the Earth.
“That 2135 fly-by is going to tweak Bennu’s orbit, potentially putting it on course for the Earth later that century. It may be destined to cause immense suffering and death.”
In an email interview earlier this week with Huffington Post, Dr. Lauretta again tried to mollify any growing fears of Bennu being a planet killer. Although current estimates place the chances of Bennu colliding with Earth at about 1 in 2,700, it is more likely, obviously, to continue passing by the Earth without impacting the planet.
Lauretta says people should not worry about Bennu, that the occurrence, should it happen, is “way in the future” and noted that “you’ve crossed the street with those odds.” Still, if the asteroid did impact the Earth?
“If Bennu did hit Earth, it would release the energy equivalent of 1,450 megatons of TNT, creating an impact crater about 5 kilometers (about 3 miles) in diameter. That’s over 70,000 times more energy than was released by the atomic bomb that fell on Hiroshima.”
By comparison, the Chelyabinsk meteor that disintegrated over Russia in February, 2013, appearing without advance warning from the direction of the Sun, was estimated to have exploded with the force of 500 kilotons of TNT, or about 20-30 times the force generated by the blast at Hiroshima. As it was, a 2013 Science investigatory report noted that the superbolide’s explosive disintegration in the atmosphere was enough to generate a shockwave that injured over 1,500 people and damaged thousands of buildings in seven large cities.
As for the OSIRIS-REx, the NASA space probe is scheduled for launch next month. According to Space.com, the spacecraft will chase down Bennu for two years, then land and acquire 2.1 ounces (60 grams) of the asteroid’s surface material in July, 2020. It is then scheduled to return to Earth so that scientists can analyze the samples.
Although OSIRIS-REx is not built for any type of deflection or redirection, NASA is working on a mission to do both and, once provided with data from the mission, will better inform NASA and the world on controlling asteroid movement should Earth find itself in imminent danger from a giant PHA (and, of course, given the time to avert said danger). There are also several plans in the works by other agencies to provide better warning systems against incoming dangerous asteroids and/or meteors, like the ATLAS system (per Space.com), as well as providing options on how to avoid potential catastrophes with asteroids like Bennu.
[Image via Shutterstock]