This is a Test: Asteroid Tracking Network Observes Close Approach
Jet Propulsion Laboraotry
October 10, 2017
On Oct. 12 EDT (Oct. 11 PDT), a small asteroid designated 2012 TC4 will
safely pass by Earth at a distance of approximately 26,000 miles (42,000
kilometers). This is a little over one tenth the distance to the Moon
and just above the orbital altitude of communications satellites. This
encounter with TC4 is being used by asteroid trackers around the world
to test their ability to operate as a coordinated international asteroid
2012 TC4 is estimated to be 50 to 100 feet (15 to 30 meters) in size.
Orbit prediction experts say the asteroid poses no risk of impact with
Earth. Nonetheless, its close approach to Earth is an opportunity to test
the ability of a growing global observing network to communicate and coordinate
its optical and radar observations in a real scenario.
Oct. 11, 2017 movie of asteroid 2012 TC4 using the 1.0-meter Kiso Schmidt
telescope in Nagano, Japan. Credit: Kiso Observatory, the University of
This asteroid was discovered by the Panoramic Survey Telescope and Rapid
Response System (Pan-STARRS) in Hawaii in 2012. Pan-STARRS conducts a
near-Earth object (NEO) survey funded by NASA's NEO Observations Program,
a key element of NASA's Planetary Defense Coordination Office. However,
2012 TC4 traveled out of the range of asteroid-tracking telescopes shortly
after it was discovered.
Based on the observations they were able to make in 2012, asteroid trackers
predicted that it should come back into view in the fall of 2017. Observers
with the European Space Agency and the European Southern Observatory were
the first to recapture 2012 TC4, in late July 2017, using one of their
large 8-meter aperture telescopes.Since then, observers around the world
have been tracking the object as it approaches Earth and reporting their
observations to the Minor Planet Center.
This "test" of what has become a global asteroid-impact early-warning
system is a volunteer project, conceived and organized by NASA-funded
asteroid observers and supported by the NASA Planetary Defense Coordination
As explained by Michael Kelley, program scientist and NASA PDCO lead for
the TC4 observation campaign, "Asteroid trackers are using this flyby
to test the worldwide asteroid detection and tracking network, assessing
our capability to work together in response to finding a potential real
No asteroid currently known is predicted to impact Earth for the next
Asteroid TC4's closest approach to Earth will be over Antarctica at 1:42
AM EDT on Oct. 12 (10:42 p.m. PDT on Oct. 11). Tens of professionally
run telescopes across the globe will be making ground-based observations
in wavelengths from visible to near-infrared to radar. Amateur astronomers
may contribute more observations, but the asteroid will be very difficult
for backyard astronomers to see, as current estimates are that it will
reach a visual magnitude of only about 17 at its brightest, and it will
be moving very fast across the sky.
Many of the observers who are participating in this exercise are funded
by NASA's NEO Observations Program, but observers supported by other countries'
space agencies and space institutions around the world are now involved
in the campaign.
Vishnu Reddy, an assistant professor at the University of Arizona's Lunar
and Planetary Laboratory in Tucson, is leading the 2012 TC4 campaign.
Reddy is principal investigator for a NASA-funded near-Earth asteroid
characterization project. "This campaign is a team effort that involves
more than a dozen observatories, universities and labs around the globe
so we can collectively learn the strengths and limitations of our near-Earth
object observation capabilities," he said. "This effort will exercise
the entire system, to include the initial and follow-up observations,
precise orbit determination, and international communications."
In September, asteroid observers were able to conduct a "pre-test" of
coordinated tracking of the close approach of a much larger asteroid known
as 3122 Florence. Florence, one of the largest known NEOs, at 2.8 miles
(4.5 kilometers) in size, passed by Earth on Sept. 1 at 18 times the distance
to the Moon. Coordinated observations of this asteroid revealed, among
other things, that Florence has two moons.
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Jet Propulsion Laboratory, Pasadena, Calif.