Last week, after a large meteor burned through the atmosphere at some ridiculous speed, exploding in midair, injuring over a thousand, Russian President Vladimir Putin thanked God that no large pieces landed in populous centers, Prime Minister Michael Medvedev joined the call for global defense against Near-Earth Objects, and the opposition leader blamed the explosion on Americans testing a new, secret weapon.
Meanwhile, this week in the United States, some federal agencies are turning their attentions skyward, wondering what can and needs to be done:
One positive action item was actually in place prior to the dual asteroid events of Feb. 15: a new Memorandum of Agreement between the Air, Space, and Cyberspace Operations Directorate of the Air Force Space Command and NASA’s Science Mission Directorate.
That document, which was signed on Jan. 18 of this year, spells out specifics for the public release of meteor data from sources such as high-flying, hush-hush U.S. government space sensors.
The recent Russian meteor event occurred after completion of the newly signed agreement and data on the recent Chelyabinsk event had been released for scientific analysis, SPACE.com has been informed by NASA and the U.S. Air Force.
As a result of that agreement, NASA’s Near Earth Object (NEO) Observation Program is receiving information on bolide/fireball events “based on analysis of data collected by U.S. government sensors.”
Also this week, Canada achieved real progress in the discussion of NEOs with the successful launch of NEOSSat:
The Near-Earth Object Surveillance Satellite (NEOSSat), launched February 25, 2013, is the latest in a proud family of world-leading Canadian satellites. The world’s first space telescope dedicated to detecting and tracking asteroids and satellites. It circles the globe every 100 minutes, scanning space near the Sun to pinpoint asteroids that may someday pass close to Earth. NEOSSat is also sweeping the skies in search of satellites and space debris as part of Canada’s commitment to keeping orbital space safe for everyone. NEOSSat applies the kind of industry-leading technology for which Canada has become known and has already demonstrated in our very successful Microvariability and Oscillations of Stars (MOST) satellite.
The suitcase-sized NEOSSat orbits approximately 800 kilometers high above the Earth, searching for near-Earth asteroids that are difficult to spot using ground-based telescopes. Due to its lofty location, it is not limited by the day-night cycle, and can operate 24/7. The hundreds of images that NEOSSat will generate per day will be downloaded and analyzed by the University of Calgary’s NEOSSat science operations centre. Through NEOSSat, Canada will contribute to the international effort to catalogue the near-Earth population of asteroids producing information that will be crucial to targeting new destinations for future space exploration missions.
Meanwhile, there are developments worth noting in the post-event detective work, as Jorge Zuluaga and Ignacio Ferrin have released a preprint of their paper on the orbital dynamics of the Chelyabinsk rock. Mike Wall explains for SPACE.com:
But some YouTube-aided detective work suggests that the meteor’s parent body belonged to the Apollo family of Earth-crossing asteroids, whose elliptical orbits take them farther than one Earth-sun distance (about 93 million miles, or 150 million kilometers) from our star at some point, researchers said ….
…. They also took into account the location of a hole in the ice of Lake Chebarkul, about 43 miles (70 km) from Chelyabinsk. Scientists think the hole was caused by a piece of the space rock that hit Earth on Feb. 15.
“According to our estimations, the Chelyabinski meteor started to brighten up when it was between 32 and 47 km up in the atmosphere,” they write in their paper, which has been posted to the online astronomy preprint site ArXiv.org. “The velocity of the body predicted by our analysis was between 13 and 19 km/s (relative to the Earth) which encloses the preferred figure of 18 km/s assumed by other researchers.”
The pair then entered these figures into a software program developed by the United States Naval Observatory called NOVAS (short for Naval Observatory Vector Astrometry), which calculated the likely orbit of the meteor’s parent body.
Bill Cooke, of NASA’s Marshall Space Flight Center, said the meteoroid originated in the asteroid belt, some two and a half AU from the sun. Additionally, nuclear weapons sensors around the world picked up low-freqency waves from the meteor’s final flight through earthly skies:
Meanwhile, the size of the meteor’s parent object has come into clearer focus, thanks to measurements made by a global network of infrasound sensors operated by the Comprehensive Test Ban Treaty Organization (CTBTO). These sensors monitor extremely low-frequency sound waves, which are a common product of nuclear explosions.
As the Russian meteor burned through Earth’s atmosphere, it generated the most powerful infrasound signal ever detected by the CTBTO network, researchers said. And this signal revealed a great deal about the asteroid’s size, speed and explosive power.
“The asteroid was about 17 meters in diameter and weighed approximately 10,000 metric tons,” Peter Brown, a physics professor at the University of Western Ontario in Canada, said in a statement. “It struck Earth’s atmosphere at 40,000 mph and broke apart about 12 to 15 miles above Earth’s surface. The energy of the resulting explosion exceeded 470 kilotons of TNT.”
That’s 30 to 40 times more powerful than the atomic bomb the United States dropped on the Japanese city of Hiroshima during World War II. The Russian fireball likely produced the most powerful such space rock blast since a 130-foot (40 m) object exploded over Siberia in 1908, flattening 825 square miles (2,137 square km) of forest.
Or, as NASA’s Cooke explained, it is “a typical asteroid from beyond the orbit of Mars.”
And what was that about sound waves? Yes, you can listen to the entry and descent of the Chelayabinsk meteorite.