On 31 March 2004, around 15:35 UTC, the asteroid is crudely estimated to have passed within approximately 1 Earth radius (R🜨) or 6,400 kilometers of the surface of the Earth (or 2.02 R🜨 from Earth's center). 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 R🜨 and GPS satellites orbit at 3.17 R🜨 from the center of the Earth.
As of 2008[update] this was the third or fourth closest approach. The first observation of 2004 FU162 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".[3] No precovery images have been found.
2004 FU162 is estimated to be approximately 6 meters in diameter.[citation needed] 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 (12.3 million km) of Earth,[4] but with an uncertainty parameter of 9,[1] the orbit is poorly determined.
Another, larger near-Earth asteroid, 2004 FH passed just two weeks prior to 2004 FU162.
A closer non-impacting approach to Earth was not known until 2008 TS26 on 9 October 2008.