If it were to enter the Earth’s atmosphere, it would have a similar effect to the Chelyabinsk meteor of 2013
An asteroid the size of a house will pass very close to Earth in October, giving scientists a chance to try out their planetary defence system.
The asteroid, known as 2012 TC4, was first spotted by the Pan-STARRS observatory in Hawaii in 2012, but its orbit meant that it could not be tracked.
Early observations indicated that it could come as close as 4,200 miles from the Earth’s surface – well within the ring of geostationary satellites.
However, new observations by the European Southern Observatory’s Very Large Telescope in Chile reveal that it will miss our planet by 27,000 miles – roughly one-eighth of the distance to the Moon – which is still very close in astronomical terms.
The asteroid is estimated to be between 30 and 100 feet (10 to 30 metres) in size, and is travelling at about 30,000 mph (14 kilometres per second).
If an asteroid of this size was to enter our atmosphere, it would have a similar effect to the Chelyabinsk meteor, which exploded in an air burst over Chelyabinsk Oblast, Russia, in February 2013.
The meteor generated a bright flash and produced a hot cloud of dust and gas. The bulk of the object’s energy was absorbed by the atmosphere, but some eyewitnesses felt intense heat from the fireball.
Scientists plan to use the close flyby of 2012 TC4 as an opportunity to test out their planetary defense system, in preparation for a real asteroid threat.
“Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterise and learn as much as possible about it,” said NASA program scientist Michael Kelley.
“This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat.”
While the main purpose of NASA’s Planetary Defense Coordination Office is to track potentially hazardous asteroids and comets, the US space agency is also putting in place measures to deflect any space rocks that are found to be on a collision course with Earth.
It is developing a special type of spacecraft called DART (Double Asteroid Redirection Test), which is about the size of a fridge, and can be fired at an asteroid with enough force to change its trajectory.
NASA plans to test out DART on a pair of asteroids named Didymos A and B, which are scheduled to make a “distant approach” to Earth in October 2022.
While small asteroids hit the Earth every day, larger ones like the Didymos twins could cause real problems if they hit us. And this is why NASA wants to use them as target practice.
Using an on-board targeting system, DART will fly itself to Didymos B and smash into it at 3.7 miles-per-second, in an impact that will be visible from Earth-based observatories.
The impact will theoretically change the speed and direction of the asteroid by just enough to shift it out of Earth’s path.