Asteroid A Mile Wide Will Hurtle Past Earth in 48 Hours – Mass Extinction Probability Creates Panic

FN53 is also not the last asteroid to brush past our planet. The next comparable rock is predicted by NASA to fly by on June 16. Codenamed Icarus, it has a one-kilometer diameter, flies almost three times as fast as 1999 FN53, and will come closer to Earth: only 21 lunar distances.

Then an even bigger asteroid, whose diameter is measured at 1 to 2.3 kilometers, is expected to fly 18.8 lunar distances away from us, at a speed of 20 km/sec.

Background

This is a planning page for asteroid (285331) 1999 FN53 in 2015 May.

1999 FN53 was discovered on 1999 Mar 31 by the Lowell Observatory Near-Earth Object Search (LONEOS).
It has an absolute magnitude of 18.3 suggesting a diameter within a factor of two of 680 m,
but otherwise its physical properties are poorly known. The asteroid will approach Earth at a distance
of ~ 0.07 au on 2015 Mar 14. We expect to obtain radar echo spectra and ranging data of this object at
Goldstone (X-band, 3.5 cm wavelength).

1999 FN53 was previously detected by the Arecibo and Goldstone radars in 1999 May when the object
made a close approach to Earth at a distance of 0.06 au. 3 doppler and 1 range measurements from that apparition
have been used in the current orbital solution.

Echo power spectra obtained at Goldstone in 1999 revealed a bandwidth of ~30 Hz and an OC radar cross section
of 0.034 km^2. Nearly every object with an absolute magnitude of 18 has a rotation period slower than 2.1 h, so if we adopt
that value as a bound, the bandwidth constrains the diameter to be larger than about 0.6 km.
This diameter constraint is also consistent
with the radar cross section, which suggests a similar diameter if the radar albedo is about 0.1.
Thus, we expect that 1999 FN53 will be a rapid rotator roughly 0.6 km in diameter.

This object was observed by NASA’s NEOWISE mission in mid-April. Preliminary results reported by J. Masierto
suggest a diameter of roughly 1 km.

Orbital and Physical Characteristics
Provisional Designation 1999 FN53
Asteroid number 285331
Discoverer LONEOS
Discovery date 1999 Mar 31
orbit type Apollo
Close approach dist. 0.068 au
Close approach dist. 26.5 lunar distances
Close approach date 2015 May 14

semimajor axis 1.735 au
eccentricity 0.455
inclination 20.2 deg
perihelion distance 0.945 au
aphelion distance 2.526 au
Tisserand parameter 3.964 Asteroidal

absolute magnitude (H) 18.3
diameter close to 1 km (J. Masiero, pers. comm.)
optical albedo unknown
rotation period unknown, but possibly fast
lightcurve amplitude unknown
pole direction unknown
spectral class unknown

Last update: 2015 Apr 27