Our home planet is due for a record setting space encounter on Friday (Feb. 15) of this week, when a space rock roughly half a football field wide skirts very close by Earth at break neck speed and well inside the plethora of hugely expensive communications and weather satellites that ring around us in geosynchronous orbit.
“There is no possibility of an Earth impact” by the Near Earth Asteroid (NEO) known as 2012 DA 14, said Don Yeomans, NASA’s foremost asteroid expert at a media briefing. Well that’s good news for us – but a little late for the dinosaurs.
At its closest approach in less than 4 days, the 45 meter (150 feet) wide Asteroid 2012 DA14 will zoom by within an altitude of 27,700 kilometers (17,200 miles). That is some 8000 km (5000 miles) inside the ring of geosynchronous satellites, but far above most Earth orbiting satellites, including the 6 person crew currently working aboard the International Space Station.
Although the likelihood of a satellite collision is extremely remote, NASA is actively working with satellite providers to inform them of the space rocks path.
The razor thin close shave takes place at about 2:24 p.m. EST (11:24 a.m. PST and 1924 UTC) as the asteroid passes swiftly by at a speed of about 7.8 kilometers per second (17,400 MPH)- or about 8 times the speed of a rifle bullet. For some perspective, it will be only about 1/13th of the distance to the moon at its closest.
“Asteroid 2012 DA14 will make a very close Earth approach, traveling rapidly from South to North and be moving at about two full moons per minute,” said Yeomans, who manages NASA’s Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. “That’s very fast for a celestial object.”
No known asteroid has ever passed so near to Earth.
“This is a record predicted close approach for a known object this size,” stated Yeomans. “Such close flybys happen every 40 years on average. An actual Earth collision would happen about every 1200 years.”
Yeomans said that if an asteroid the size of 2012 DA14 fell to Earth, the impact effect would be similar to the 1908 Tunguska event in Siberia. That was an air blast event that leveled trees over an area greater than about 800 square miles.
So the local effect on human cities for example of a 50 meter wide asteroid impact would be deadly and utterly devastating. But it would not be catastrophic to all life on Earth. Nevertheless, at this moment, Earth has no defenses against asteroids other than talk.
By comparison, the K-T event that caused the mass extinction of the dinosaurs some 65 million years ago was caused by an asteroid about 10 km (6 mi) in diameter. About 2/3 of all species went extinct. If 2012 DA14 impacted Earth the force would be equivalent to about 2.4 megatons of energy (2.4 million tons of TNT), said Yeomans.
There is no danger to the ISS crew and apparently they won’t have any chance to observe it.
“The ISS is not positioned right for observations,” Lindley Johnson, program executive, Near Earth Object Observations Program, NASA Headquarters, Washington, told Universe Today.
“No NASA space-based assets will be making measurements,” Lindley told me. “The asteroid is moving to fast.”
However, radar astronomers do plan to take images around eight hours after the flyby using the Goldstone antenna in California’s Mojave Desert, which is part of NASA’s Deep Space Network.
Some skilful and knowledgeable Earthlings might have a chance to see the asteroid hurtling by with binoculars or a small telescope.
“The asteroid will be observable in the dark sky in Eastern Europe, Asia and Australia, achieving about 7.5 magnitude, somewhat fainter than naked eye visibility,” explained Yeomans. “Closest approach will be over Indonesia.”
Astronomers at the La Sagra Sky Survey program in southern Spain discovered the asteroid in February 2012 just after its last Earth flyby, at a fairly distant 7 Earth-Moon distances. They reported the finding to the Minor Planet Center.
NASA’s NEO group and collaborators in Pisa, Italy then use such data to predict future flight paths and look into past trajectories as well.
Yeomans said that the Feb 15 flyby will be the closest for the next 100 years and its orbit will be perturbed so that it comes back less frequently – changing its orbital class from Apollo to Aten.
Due to its small size and recent discovery, not much is known about the composition of 2012 DA14. It might be silicate rock.
Small space rocks hit Earth on a daily basis amounting to about 100 tons. Car sized rocks hit weekly.
Stay Alert !