Tiny Asteroid Discovered Saturday Disintegrates Hours Later Over Southern Africa
Asteroid 2018 LA entered Earth's atmosphere at about 9:44 a.m. PDT (12:44 p.m. EDT, 16:44 UTC), and later disintegrated in the upper atmosphere near Botswana, Africa.
A boulder-sized asteroid
designated 2018 LA was discovered Saturday morning, June 2, and was determined
to be on a collision course with Earth, with impact just hours away. Because it
was very faint, the asteroid was estimated to be only about 6 feet (2 meters)
across, which is small enough that it was expected to safely disintegrate in
Earth's
atmosphere. Saturday's asteroid was first discovered by the NASA-funded Catalina Sky Survey,
located near Tucson and operated by the University of Arizona.Did you ever wonder how NASA spots asteroids that maybe getting too close to Earth for comfort? Watch and learn. Find out more about NASA finds, studies and tracks near-Earth objects by visitinghttps://www.nasa.gov/planetarydefense.Although there was not enough
tracking data to make precise predictions ahead of time, a swath of possible
locations was calculated stretching from Southern Africa, across the Indian
Ocean, and onto New Guinea. Reports of a bright fireball above Botswana,
Africa, early Saturday evening match up with the predicted trajectory for the
asteroid. The asteroid entered Earth's atmosphere at the high speed of 10 miles per
second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m.
PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana
time) and disintegrated several miles above the surface, creating a bright
fireball that lit up the evening sky. The event was witnessed by a number of
observers and was caught on webcam video.https://www.youtube.com/watch?v=rnBvSNYy-EYWhen it was first detected,
the asteroid was nearly as far away as the Moon's orbit, although that was not initially known.
The asteroid appeared as a streak in the series of time-exposure images taken by
the Catalina telescope . As is the case for all asteroid-hunting projects, the
data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts,
which calculated a preliminary trajectory indicating the possibility of an
Earth impact. The data were in turn sent to the Center for Near-Earth Object
Studies (CNEOS) at NASA's Jet Propulsion Laboratory in Pasadena, California,
where the automated Scout system also found a high probability that the
asteroid was on an impact trajectory. Automated alerts were sent out to the
community of asteroid observers to obtain further observations, and to the
Planetary Defense Coordination Office at NASA Headquarters in Washington.
However, since the asteroid was determined to be so small and therefore harmless,
no further impact alerts were issued by NASA."This
was a much smaller object than we are tasked to detect and warn about," said Lindley Johnson,
Planetary Defense Officer at NASA Headquarters. "However, this real-world event allows us to
exercise our capabilities and gives some confidence our impact prediction
models are adequate to respond to the potential impact of a larger object."The ATLAS asteroid survey
obtained two additional observations hours before impact, which were used by
Scout to confirm the impact would occur, and narrowed down the predicted
location to southern Africa. Infrasound data collected just after the impact
clearly detected the event from one of the listening stations deployed as part
of the International Monitoring System of the Comprehensive Nuclear-Test-Ban
Treaty. The signal is consistent with an atmospheric impact over Botswana."The discovery of asteroid 2018 LA is only the third time that an asteroid has been discovered to be on an impact trajectory, said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL.  "It is also only the second time that the high probability of an impact was predicted well ahead of the event itself."The first event of this
kind was the impact of asteroid 2008 TC3, which lit up the predawn sky above
Northern Sudan on October 7, 2008. That was a slightly larger asteroid (about
13 feet, or 4 meters in size), and it was discovered a full 19 hours before impact,
allowing for a large number of follow-up observations and a very precise
trajectory to be calculated. The second predicted impact event was for asteroid
2014 AA, which was discovered only a few hours before impact on Jan. 1, 2014,
in the Atlantic Ocean, leaving too little time for follow-up observations. The
Catalina Sky Survey has been responsible for discovering all three of these
small asteroids on impact trajectories, and all on the watch of the same
observer, Richard Kowalski.NASA's Planetary Defense
Coordination Office is responsible for finding, tracking and characterizing
potentially hazardous asteroids and comets coming near Earth, issuing warnings
about possible impacts, and assisting coordination of U.S. government response
planning, should there be an actual impact threat. JPL hosts the Center
for Near-Earth Object Studies for NASA's Near-Earth Object Observations
Program, an element of the Planetary Defense Coordination Office within the
agency's Science Mission Directorate.For
more information about NASA's Planetary Defense Coordination Office, visit:https://www.nasa.gov/planetarydefenseMore
information about asteroids and near-Earth objects can be found at:https://cneos.jpl.nasa.govhttps://www.jpl.nasa.gov/asteroidwatchFor asteroid and comet news and
updates, followAsteroidWatchon Twitter.twitter.com/AsteroidWatchStory updated as of 9:00pm PST.