This diagram shows the orbit of asteroid 2013 TV135
(in blue), which has just a 1-in-63,000 chance of impacting Earth. Its risk to
Earth will likely be further downgraded as scientists continue their
investigations.
Image Credit: NASA/JPL-Caltech
Newly discovered asteroid 2013 TV135 made a close approach to Earth on Sept.
16, when it came within about 4.2 million miles (6.7 million kilometers). The
asteroid is initially estimated to be about 1,300 feet (400 meters) in size and
its orbit carries it as far out as about three quarters of the distance to
Jupiter's orbit and as close to the sun as Earth's orbit. It was discovered on
Oct. 8, 2013, by astronomers working at the Crimean Astrophysical Observatory in
Ukraine. As of Oct. 14, asteroid 2013 TV135 is one of 10,332 near-Earth objects
that have been discovered.
With only a week of observations for an orbital period that spans almost four
years, its future orbital path is still quite uncertain, but this asteroid could
be back in Earth’s neighborhood in 2032. However, NASA’s Near-Earth Object
Program Office states the probability this asteroid could then impact Earth is
only one in 63,000. The object should be easily observable in the coming months
and once additional observations are provided to the Minor Planet Center in
Cambridge, Mass., the initial orbit calculations will be improved and the most
likely result will be a dramatic reduction, or complete elimination, of any risk
of Earth impact.
"To put it another way, that puts the current probability of no impact in
2032 at about 99.998 percent," said Don Yeomans, manager of NASA's Near-Earth
Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "This
is a relatively new discovery. With more observations, I fully expect we will be
able to significantly reduce, or rule out entirely, any impact probability for
the foreseeable future."
NASA detects, tracks and characterizes asteroids and comets passing close to
Earth using both ground- and space-based telescopes. The Near-Earth Object
Observations Program, commonly called "Spaceguard," discovers these objects,
characterizes a subset of them and identifies their orbits to determine if any
could be potentially hazardous to our planet.
JPL manages the Near-Earth Object Program Office for NASA's Science Mission
Directorate in Washington. JPL is a division of the California Institute of
Technology in Pasadena.
More information about asteroids and near-Earth objects is at:
A team of NASA and international scientists for the first time has gathered a
detailed understanding of the effects on Earth from a small asteroid
impact.
The unprecedented data obtained as the result of the airburst of a meteoroid
over the Russian city of Chelyabinsk on Feb. 15, has revolutionized scientists'
understanding of this natural phenomenon.
The Chelyabinsk incident was well observed by citizen cameras and other
assets. This factor provided a unique opportunity for researchers to calibrate
the event, with implications for the study of near-Earth objects (NEOs) and the
development of hazard mitigation strategies for planetary defense. Scientists
from nine countries now have established a new benchmark for future asteroid
impact modeling.
"Our goal was to understand all circumstances that resulted in the shock
wave," said meteor expert Peter Jenniskens, co-lead author of a report published
in the journal Science.
Jenniskens, a meteor astronomer at NASA’s Ames Research Center and the SETI
Institute, participated in a field study led by Olga Popova of the Institute for
Dynamics of Geospheres of the Russian Academy of Sciences in Moscow in the weeks
following the event.
“It was important that we followed up with the many citizens who had
firsthand accounts of the event and recorded incredible video while the
experience was still fresh in their minds," said Popova.
By calibrating the video images from the position of the stars in the night
sky, Jenniskens and Popova calculated the impact speed of the meteor at 42,500
mph (19 kilometers per second). As the meteor penetrated through the atmosphere,
it fragmented into pieces, peaking at 19 miles (30 kilometers) above the
surface. At that point the superheated meteor appeared brighter than the sun,
even for people 62 miles (100 kilometers) away.
Because of the extreme heat, many pieces of the meteor vaporized before
reaching Earth. Scientists believe that between 9,000 to 13,000 pounds (4,000 to
6,000 kilograms) of meteorites fell to the ground. This amount included one
fragment weighing approximately 1,400 pounds (650 kilograms). This fragment
wasrecovered from Lake Chebarkul on Oct. 16 by professional divers guided by
Ural Federal University researchers in Yekaterinburg, Russia.
NASA researchers participating in the 59 member consortium study suspect the
abundance of shock fractures in the rock contributed its breakup in the upper
atmosphere. Meteorites made available by Chelyabinsk State University
researchers were analyzed to learn about the origin of the shock veins and their
physical properties. Shock veins are caused by asteroid collisions. When
asteroid collide with each other, heat generated by the impact causes iron and
nickel components of the objects to melt. These melts cool into thin masses,
forming metal veins – shock veins – in the objects.
"One of these meteorites broke along one of these shock veins when we pressed
on it during our analysis," said Derek Sears, a meteoriticist at Ames.
Mike Zolensky, a cosmochemist at NASA’s Johnson Space Center in Houston, may
have found why these shock veins (or shock fractures), were so frail. They
contained layers of small iron grains just inside the vein, which had
precipitated out of the glassy material when it cooled.
"There are cases where impact melt increases a meteorite's mechanical
strength, but Chelyabinsk was weakened by it," said Zolensky.
The impact that created the shock veins may have occurred as long ago as 4.4
billion years. This would have been 115 million years after the formation of the
solar system, according to the research team, who found the meteorites had
experienced a significant impact event at that time.
“Events that long ago affected how the Chelyabinsk meteoroid broke up in the
atmosphere, influencing the damaging shockwave,” said Jenniskens.
NASA’s Near-Earth Object Program sponsors research to better understand the
origin and nature of NEOs. These essential studies are needed to inform our
approach to preparing for the potential discovery and deflection of an object on
a collision course with the Earth.
NASA's recently announced asteroid initiative includes the first mission to
capture and relocate an asteroid, as well as a grand challenge to find and
characterize all asteroid threats to human population. It represents an
unprecedented technological feat that will lead to new scientific discoveries
and technological capabilities that will help protect our home planet.
Aside from representing a potential threat, the study of asteroids and comets
represent a valuable opportunity to learn more about the origins of our solar
system, the source of water on the Earth, and even the origin of organic
molecules that lead to the development of life.
For more information about the Chelyabinsk field study visit:
For more information on asteroids and comets, visit:
For more information about NASA, visit:
NASA
Guillermo Gonzalo Sánchez Acgutegui
