2004 FU162
is an Aten near-Earth asteroid less than 20 meters in diameter crudely estimated to have passed roughly 6500 km above the surface of Earth on 31 March 2004.
It was only observed for 44 minutes on 31 March 2004, by the Lincoln Near-Earth Asteroid Research team at Lincoln Laboratory's Experimental Test Site in Socorro, New Mexico, and remains a lost asteroid. The estimated 4 to 6 meter sized body made one of the closest known approaches to Earth.
Description
On 31 March 2004, around 15:35 UTC, the asteroid is crudely estimated to have passed within approximately 1 Earth radius or 6,400 kilometers of the surface of the Earth. But due to the very short observation arc, the uncertainty in the close approach distance is a large ±15000 km. By comparison, geostationary satellites orbit at 5.6 and GPS satellites orbit at 3.17 from the center of the Earth.this was the third or fourth closest approach. The first observation of was not announced until 22 August 2004.
It was only observed four times in the space of 44 minutes and could not be followed up. Nevertheless, "the orbit is quite determinate and, given the exceptional nature of this close approach, the object is now receiving a designation". No precovery images have been found.
is estimated to be approximately 6 meters in diameter. This means that it would burn up from atmospheric friction before striking the ground in the case of an Earth impact.
On 26 March 2010, it may have come within 0.0825 AU of Earth, but with an uncertainty parameter of 9, the orbit is poorly determined.
Another, larger near-Earth asteroid, 2004 FH passed just two weeks prior to.
A closer non-impacting approach to Earth was not known until on 9 October 2008.