Varias fuentes confirman que el primer asteroide descubierto en 2014, designado 2014 AA, entró en la atmósfera de la Tierra a finales 01 de enero (02 de enero de tiempo universal) sobre el Océano Atlántico. El Catalina Sky Survey operando cerca de Tucson, Arizona descubrió este pequeño asteroide - 6 a 9 pies (2 a 3 metros) de tamaño - en la madrugada del 01 de enero, y de inmediato hizo un seguimiento de ella. (Una animación de las imágenes de descubrimiento se muestra en la Figura 1). El asteroide entró en la atmósfera de la Tierra unas 21 horas después, y probablemente se destruyó.
Comunicado de la NASA:
Several
sources confirm that the first discovered asteroid in 2014, designated 2014 AA,
entered Earth’s atmosphere late Jan. 1 (Jan. 2 Universal time) over the
mid-Atlantic Ocean. The Catalina Sky Survey operating near Tucson, Ariz.
discovered this very small asteroid -- 6 to 9 feet (2 to 3 meters) in size --
early on the morning of Jan. 1, and immediately followed up on it. (An animation of the discovery images is
shown in Figure 1). The asteroid entered Earth’s atmosphere about 21 hours
later, and probably broke up.
The
high-precision astrometry data and rapid follow-up observations provided by the
Catalina Sky Survey team made it possible for orbit analysts from NASA's
Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena,
Calif., to determine possible Earth impact locations. Before that, and based
upon the Catalina Sky Survey observations, Steve Chesley of JPL produced a plot
of the possible impact locations for asteroid 2014 AA. (Chesley's graphic is
shown in Figure 2, where the blue, nearly horizontal band represents the region
of possible impacts).
The
geolocation derived by Chesley allowed Peter Brown of the University of Western
Ontario, and Petrus Jenniskens of the SETI Institute, Mountain View, Calif., to
search the data from low-frequency infrasound observation sites of the
Comprehensive Nuclear-Test-Ban Treaty Organization. They found weak signals
from stations in Bolivia, Brazil and Bermuda that indicated that the likely
impact location was indeed positioned within the predicted area. The location,
marked with a red dot, is still somewhat uncertain due to observational
factors, including atmospheric effects on the propagation of infrasound
signals.
Infrasound
stations record ultra-low-frequency sound waves to monitor the location of
atmospheric explosions. These sites often pick up airbursts from small asteroid
impacts, commonly called fireballs or bolides. There are about a billion
near-Earth objects in the size range of 2014 AA, and impacts of comparably
sized objects occur several times each year.
Uncertainties
present in the infrasound technique and the very limited amount of optical
tracking data before impact make it difficult to pinpoint the impact time and
location. Even so, Chesley provides the following estimate:
Impact
time: Jan. 1, 2014 at 11:02 p.m. EST (Jan. 2 4:02 UTC)
Impact
location coordinates: 11.7 degrees north
latitude, 319.7 degrees latitude.
This
information is preliminary and has uncertainties of perhaps a few hundred
kilometers, or miles, in location, and tens of minutes in time.
Prior
to impact, the orbit of 2014 AA had a very low inclination (about 1 degree)
with respect to the ecliptic plane and an orbit that ranged from 0.9 to 1.3
astronomical units from the sun, with an orbital period of about 1.2 years.
http://www.nasa.gov/jpl/asteroid/first-2014-asteroid-20140102/
