Astronomers Practice Responding to a Killer Asteroid”

Beyond the Earth-Moon system, thousands of asteroids known as Near-Earth Objects (NEOs) are known to exist. These rocks periodically cross Earth’s orbit and make close a flyby of Earth. Over the course of millions of years, some even collide with the Earth, causing mass extinctions. Little wonder then why NASA’s Center for Near Earth Object Studies (CNEOS) is dedicated to monitoring the larger objects that occasionally come close to our planet.

One of these objects is 2012 TC4, a small and oblong-shaped NEO that was first spotted in 2012 during a close flyby of Earth. During its most recent flyby – which took place on Thursday, October 12th,2017 – an international team of astronomers led by NASA scientists used the opportunity to conduct the first international exercise to test global responses to an impending asteroid strike.

This exercise was known as the “TC4 Observation Campaign“, which began this past July and concluded with the asteroid flyby. It all began when astronomers at the European Southern Observatory’s (ESO) Paranal Observatory in Chile used the Very Large Telescope (VLT) to recover 2012 TC4. When the asteroid made its final close approach to Earth in mid-October, it passed Earth by at a distance of 43,780 km (27,200 mi).

Diagram showing 2012 TC4’s heliocentric orbit, which has changed due to the 2012 and 2017 close encounters with Earth. Credit: NASA/JPL-Caltech

The goal of this exercise was simple: recover, track and characterize a real asteroid as if it were likely to collide with Earth. In addition, the exercise was an opportunity to test the International Asteroid Warning Network, which conducts observations of potentially hazardous asteroids, attempts to model their behavior, make predictions, and share these findings with institutions around the world.

On Oct. 12th, TC4 flew by Earth at roughly 0.11 times the distance between Earth and the Moon. In the months leading up to the flyby, astronomers from the US, Canada, Columbia, Germany, Israel, Italy, Japan, the Netherlands, Russia and South Africa tracked TC4 from the ground. At the same time, space-based telescopes studied the asteroid’s orbit, shape, rotation and composition.

Detlef Koschny is the co-manager of the Near-Earth Object segment in the European Space Agency (ESA)’s Space Situational Awareness program. As he was quoted in a recent NASA press release:

“This campaign was an excellent test of a real threat case. I learned that in many cases we are already well-prepared; communication and the openness of the community was fantastic. I personally was not prepared enough for the high response from the public and media – I was positively surprised by that! It shows that what we are doing is relevant.”

Asteroid 2012 TC4 appears as a dot at the center of this composite of 37 individual 50-second exposures obtained on Aug. 6, 2017 by the European Southern Observatory’s Very Large Telescope. Credit: NASA/JPL-Caltech

Based on their observations, scientists at CNEOS – which is located at the Jet Propulsion Laboratory in Pasadena, California – were able to determine all the necessary characteristics of TC4. This included its precise orbit, the distance it would pass by Earth on Oct. 12th, and discern if there was any possibility of a future impact. As Davide Farnocchia, a member of CNEOS who led the effort to determine the asteroid’s orbit, explained:

“The high-quality observations from optical and radar telescopes have enabled us to rule out any future impacts between the Earth and 2012 TC4. These observations also help us understand subtle effects such as solar radiation pressure that can gently nudge the orbit of small asteroids.”

Multiple observatories also dedicated their optical telescopes to studying how fast TC4 rotates. As Eileen Ryan – the director of the Magdalena Ridge Observatory, which conducted observations of the asteroids rotation – indicated, “The rotational campaign was a true international effort. We had astronomers from several countries working together as one team to study TC4’s tumbling behavior.”

What they found that the small asteroid rotated slowly, which was rather surprising. Whereas small asteroids typically rotate very quickly, TC4 had a rotational period of just 12 minutes, and also appeared to be tumbling. Other observations revealed some interesting things about the shape of TC4.

The Green Bank Telescope, located in West Virginia. Credit: NRAO

These were conducted by astronomers using NASA’s Goldstone Deep Space Network antenna in California, and the National Radio Astronomy Observatory‘s Green Bank Telescope in West Virginia. Their reading helped refine size estimates of the asteroid, indicating that it is elongated and measures approximately 15 meters (50 ft) long and 8 meters (25 feet) wide.

Determining TC4’s composition was more challenging. Due to unfavorable weather conditions that coincided with the flyby, instruments like NASA’s Infrared Telescope Facility (IRTF) at the Mauna Kea Observatory in Hawaii were unable to get a good look at the asteroid. However, spectra was obtained on the asteroid that indicated that it has a rocky body, which means it is an S-type asteroids.

Typically, ground-based elements determine an asteroid’s composition based on their color. Whereas dark asteroids are known for being carbon-rich (C-type), bright asteroids are predominantly composed of silicate minerals (S-type). As Lance Benner, who led the radar observations at JPL, explained:

“Radar has the ability to identify asteroids with surfaces made of highly reflective rocky or metallic materials. We were able to show that radar scattering properties are consistent with a bright rocky surface, similar to a particular class of meteorites that reflect as much as 50 percent of the light falling on them.”

In addition to the observation campaign, NASA used TC4’s latest flyby as an opportunity to test communications between observatories, as well as the internal messaging and communications system that is currently in place. This network connects various government agencies and the executive branch and would come into play in the event of a predicted impact emergency.

Asteroid 2012 TC4 projected flyby of the Earth-Moon system, which was calculated well before it took place. Credits: NASA/JPL-Caltech

According to Vishnu Reddy, an assistant professor from the University of Arizona’s Lunar and Planetary Laboratory who led the observation campaign, this aspect of the exercise “demonstrated that we could organize a large, worldwide observing campaign on a short timeline, and communicate results efficiently.”Michael Kelley, the TC4 exercise lead at NASA Headquarters in Washington, added,”We are much better prepared today to deal with the threat of a potentially hazardous asteroid than we were before the TC4 campaign.”

Last, but not least, was the way the exercise brought scientists and institutions from all around the world together for a single purpose. As Boris Shustov – the science director for the Institute of Astronomy at the Russian Academy of Sciences, who was also part of the exercise – indicated, the exercise was an excellent way to test how the world’s scientific institutions would go about prepping for a possible asteroid impact:

“The 2012 TC4 campaign was a superb opportunity for researchers to demonstrate willingness and readiness to participate in serious international cooperation in addressing the potential hazard to Earth posed by NEOs. I am pleased to see how scientists from different countries effectively and enthusiastically worked together toward a common goal, and that the Russian-Ukrainian observatory in Terskol was able to contribute to the effort. In the future I am confident that such international observing campaigns will become common practice.”

In the event that a Near-Earth asteroid might actually pose a threat the Earth, it is good to know that all the tracking, monitoring and alert systems we have in place are in good working order. If we are going to trust the fate of human civilization (and possibly all life on Earth) to an advanced warning system, it just makes sense to have all the bugs worked out beforehand!

The TC4 Observation Campaign is sponsored by NASA’s Planetary Defense Coordination Office, which in turn is managed by the Planetary Science Division of the Science Mission Directorate at NASA Headquarters in Washington, D.C.

Further Reading: NASA

Watch a House-Sized Asteroid Pass Close to Earth Tonight (October 11/12)

On Oct. 12, a house-size asteroid will pass quite close to Earth – only 26,000 miles (42,000 kilometers) away. This is just above the orbital altitude of communications satellites and a little over one-tenth the distance to the Moon. But not to fear, it has no chance of hitting Earth.

Artists concept of Asteroid 2012 TC4’s close pass of Earth on Oct. 12, 2017. Based on continuing observations, scientists have determined that it will pass the Earth at a distance of about 26,000 miles (42,000 kilometers). Credits: NASA/JPL-Caltech

Asteroid 2012 TC4 was discovered almost 4 years ago to the day, on October 4, 2012, just a week before it made another close pass by Earth.

With a little more advance notice this time around, NASA and asteroid trackers around the world are using the close pass to test their ability to operate as a coordinated International Asteroid Warning Network. This is a growing global observing network to communicate and coordinate their optical and radar observations in a real scenario.

“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 asteroid-impact threat,” said Michael Kelley, program scientist and NASA lead for the TC4 observation campaign. You can read more details about the observing campaign in our previous article.

You can watch it pass by too, if you have a at least an 8 inch telescope, according to our David Dickinson, who has a very informative post about 2012 TC4 at Sky & Telescope.

Closest approach will be at on October 12, 2017, at 5:41 Universal Time (1:41 a.m. EDT).

You can also watch a couple of webcasts of the pass:

Virtual Telescope will have a live feed, and the Slooh Telescope crew will also host a live feed starting tonight at 8 pm EDT on Oct. 11.

2012 TC4 is estimated to be 45 to 100 feet (15 to 30 meters) in size.

NASA’s Asteroid Watch says that no asteroid currently known is predicted to impact Earth for at least the next 100 years.

More info at NASA’s website.

Impending Asteroid Flyby Will be a Chance to Test NASA’s Planetary Defense Network!

This coming October, an asteroid will fly by Earth. Known as 2012 TC4, this small rock is believed to measure between 10 and 30 meters (30 and 100 feet) in size. As with most asteroids, this one is expected to sail safely past Earth without incident. This will take place on October 12th, when the asteroid will pass us at a closest estimated distance of 6,800 kilometers (4,200 miles) from Earth’s surface.

That’s certainly good news. But beyond the fact that it does not pose a threat to Earth, NASA is also planning on using the occasion to test their new detection and tracking network. As part of their Planetary Defense Coordination Office (PDCO), this network is responsible for detecting and tracking asteroids that periodically pass close to Earth, which are known as Potentially Hazardous Objects (PHOs)

In addition to relying on data provided by NASA’s Near-Earth Object (NEO) Observations Program. the PDCO also coordinates NEO observations conducted by National Science Foundation (NSF)-sponsored ground-based observatories, as well as space situational awareness facilities run by the US Air Force. Aside from finding and tracking PHOs, the PDCO is also responsible for coming up with ways of deflecting and redirecting them.

On Oct. 12, 2017, asteroid 2012 TC4 will safely fly past Earth at an estimated distance of 6,800 km (4,200 mi). Credits: NASA/JPL-Caltech

The PDCO was officially created in response to the NASA Office of Inspector General’s 2014 report, titled “NASA’s Efforts to Identify Near-Earth Objects and Mitigate Hazards.” Citing such events as the Chelyabinsk meteor, and how such events are relatively common, the report indicated that coordination, early warning and mitigation strategies were needed for the future:

“[I]n February 2013 an 18-meter (59 foot) meteor exploded 14.5 miles above the city of Chelyabinsk, Russia, with the force of 30 atomic bombs, blowing out windows, destroying buildings, injuring more than 1,000 people, and raining down fragments along its trajectory… Recent research suggests that Chelyabinsk-type events occur every 30 to 40 years, with a greater likelihood of impact in the ocean than over populated areas, while impacts from objects greater than a mile in diameter are predicted only once every several hundred thousand years.”

The PDCO was established in 2016, which makes this upcoming flyby the first chance they will have to test their network of observatories and scientists dedicated to planetary defense. Michael Kelley is the program scientist and the NASA Headquarters lead for the TC4 observation campaign, which has been monitoring 2012 TC4 for years. As he said in a recent NASA press statement:

“Scientists have always appreciated knowing when an asteroid will make a close approach to and safely pass the Earth because they can make preparations to collect data to characterize and learn as much as possible about it. This time we are adding in another layer of effort, using this asteroid flyby to test the worldwide asteroid detection and tracking network, assessing our capability to work together in response to finding a potential real asteroid threat.”

Diagram showing the data gathered from 1994-2013, indicating daytime (orange) and nighttime (blue) impacts of small meteorites. Credit: NASA

In addition, the flyby will be an opportunity to reacquire 2012 TC4, which astronomers lost track of in 2012 when it moved beyond the range of their telescopes. For this reason, people like Professor Vishnu Reddy of the University of Arizona are also excited. A member of the Lunar and Planetary Laboratory, Reddy also leads the campaign to reacquire the asteroid. As he indicated, this flyby will be a chance for collaborative observation.

“This is a team effort that involves more than a dozen observatories, universities and labs across 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.”

2012 TC4 was originally discovered on Oct. 5th, 2012, by the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) at the Haleakala Observatory in Hawaii. After it sped past Earth in that same year, it has not been directly observed since. And while it is slightly larger than the meteor that exploded in Earth’s atmosphere near Chelyabinsk, Russia, in 2013, scientists are certain that it will pass us by at a safe distance.

This is based on tracking data that was collected by scientists from NASA’s Center for Near-Earth Object Studies (CNEOS). After monitoring 2012 TC4 for a period of seven days after it was discovered in 2012, they determined that at its closest approach, the asteroid will pass no closer than 6,800 km (4,200 mi) to Earth. However, it is more likely that it will pass us at distance of about 270,000 km (170,000 mi).

The Pan-Starrs telescope at dawn. The mountain in the distance is Mauna Kea, about 130 kilometers southeast. Credit: pan-starrs.ifa.hawaii.edu

This would place it at a distance that is about two-thirds the distance between the Earth and the Moon. The last time this asteroid passed Earth, it did so at a distance that was one-quarter the distance between the Earth and the Moon. Therefore, the odds of it passing by without incident are even greater this time around. So rather than representing a threat, the passage of this asteroid represents a good chance for research.

As Paul Chodas, the manager of the CNEOS at NASA’s Jet Propulsion Laboratory, stated:

“This is the perfect target for such an exercise because while we know the orbit of 2012 TC4 well enough to be absolutely certain it will not impact Earth, we haven’t established its exact path just yet. It will be incumbent upon the observatories to get a fix on the asteroid as it approaches, and work together to obtain follow-up observations than make more refined asteroid orbit determinations possible.”

By monitoring 2012 TC4 as it flies by, astronomers will be able to refine their knowledge about the asteroid’s orbit, which will help them to predict and calculate future flybys with even greater precision. This will further mitigate the risk posed by PHOs down the road, and help the PDCO to develop and test strategies to address possible future impacts.

In short, remain calm! This flyby is a good thing!

Further Reading: NASA

Asteroid 2012 TC4 to Buzz Earth on October 12

Asteroid 2012 TC4 as seen by the Remanzacco Observatory team of Ernesto Guido, Giovanni Sostero, Nick Howes on Oct. 9, 2012.

Asteroid 2012 TC4 will give Earth a relatively close shave on October 12, 2012, passing at just a quarter of the distance to the orbit of the Moon. Discovered by Pan-STARRS observatory in Hawaii just last week on October 4, 2012, and it will pass by at about 88,000 kilometers (59,000 miles) away. Estimates on the size of this space rock vary from 17 to 30 meters, but NASA has indicated they will have telescopes trained on the asteroid as it makes its near Earth flyby — closest approach is just before 06:00 UTC (2:00 a.m. EDT) on Friday. Radar measurements can provide more details on the asteroid’s size and orbital characteristics.

NASA’s Asteroid Watch has assured there is no chance this asteroid will hit Earth.

The Slooh Space Camera is providing live coverage RIGHT NOW (at the time of this posting) on Thursday, October 11th, live on Slooh.com, free to the public, starting at 2:30 p.m. PDT / 5:30 p.m. EDT / 21:30 UTC — accompanied by real-time discussions with Slooh President, Patrick Paolucci; Slooh Outreach Coordinator, Paul Cox; and Astronomy Magazine columnist, Bob Berman.

Viewers are in for a special treat as asteroid TC4 will be in the same field of view as the planet Neptune during Slooh’s live coverage.

According Astro Bob, at around the time of closest approach, 2012 TC4 will be sailing through the stars of Sagittarius at approximately one degree (two full moon diameters) every 5 minutes.

This asteroid will reach the magnitude 13.7 on October 12 around 02:00 UTC, according to the Remanzacco Observatory team of Ernesto Guido, Giovanni Sostero, Nick Howes.

You can see an animation of Remanzacco’s observations here.

A view of the orbital parameters of asteroid 2012 TC4 from JPL.