When Earth gets paid a visit, Earthlings appreciate some advance warning. Typically that’s a year or more, but NASA was only able to give three weeks’ notice in the case of asteroid 2015 TB145, which is scheduled to make a close pass by on Halloween.
Eerily, NASA Administrator Charles Bolden warned the House Science, Space, and Technology Committee of the possibility of having such short notice two years ago in March 2013.
“From the information we have, we don’t know of an asteroid that will threaten the population of the United States,” he said. “But if it’s coming in three weeks…pray.”
With an estimated diameter of 689 to 2,133 feet (210 to 650 meters) and traveling 78,000 miles (125,529 kilometers) per hour, asteroid 2015 TB145 travels along an “extremely eccentric” orbit and has an encounter velocity of 22 miles (35 km) per second, which is “unusually high,” according to NASA.
To fill this gap, NASA launched a grassroots program called The Grand Challenge in 2013 to encourage amateurs to keep a look out. In addition, NASA has an Asteroid Robotic Redirect Mission dedicated to building an asteroid lander to bump or gravitationally attract asteroids, as well as collect pieces from them for further study.
The most recent case of a meteor doing damage on Earth occurred in February of 2013, when a giant fireball impacted the atmosphere over central Russia. Despite its brightness, it came without warning because of its closeness to the Sun. Although never touching the ground, its explosion 17,200 miles from Earth released 20-30 times the energy of the atom bomb dropped on Hiroshima. About 1,500 people went to the hospital, mostly because of injuries from broken glass and other indirect consequences of the event.
NASA has identified 13,256 Near-Earth objects (NEOs) and classified 1,635 of them as Potentially Hazardous Asteroids (PHAs) due to their size.
