There was a NOVA PBS documentary recently about the threat posed by asteroids to the earth, which discussed plans to send the Sentinel satellite into space. The Sentinel satellite was designed specifically to detect asteroids that we cannot otherwise see, because they come from the direction of the sun and we are blinded by the sunlight. And that is exactly where this particular undetected asteroid that could have hit earth came from:
But funding for Sentinel was canceled by the government in 2015, despite it being very inexpensive as compared to other things we waste trillions of dollars on, which leaves us blind to asteroids. We know that it is only a matter of time before another significant asteroid hits the earth.
Not to be pedantic, but...for what it's worth and at least in this particular case, the satellite wouldn't have been able to detect it because both the original version - as well as its identical planned reboot, the NEO Surveyor (due to deploy in 2026) - are only designed to track asteroids with a mean diameter of ~150m.
