Russia encountered in 2013, one of the most tragic events in the city of Chelyabinsk, after an asteroid collision. The consequences ended the lives of over a thousand people. Such an asteroid might approach Earth again, according to an expert. Express states that Emeritus Professor Alan Harris and the German Aerospace Center warns of a considerable amount of space objects that can quickly shift past the space agency trackers undetected. Prof. Harris detailed that compared to PHOs (Potentially Hazardous Objects), which are kilometer-sized, space agencies have already identified most of the space objects almost 90 to 95 %, whereas the asteroids might crash in undetected. Space Objects Might Come in Undetected The Chelyabinsk asteroid was a nearly small space object, almost 20 meters. It crashed the Russian city, harming over 1,200 people with a burst estimated to be more than 40 times larger than the Hiroshima bomb event. Prof. Harris thinks that current technology can't detect precisely those types of asteroids. "Anything like that, I'd say up to 50 meters or so these days, could slip through defenses and hit the Earth without warning at all as Chelyabinsk did," explained Prof. Harris. The sorts of asteroids explosions are little, but never down to zero. Even a week wouldn't be enough for space agencies to deflect an oncoming space object, it will still offer time to alert people of a possible collision. Prof. Hariss detailed that people could be warned to stay as far away from all the buildings with weak structures that might easily crash. Also, people should pick an area that they're sure of the building's construction. NASA has under development a type of technology that can deflect any space objects. The space agency prepares even a mission dubbed DART (Double Asteroid Redirection Test), where scientists will liftoff a probe into space to kick off an approaching asteroid. The DART mission will begin in 2022.