Astronomy Magazine article on Asteroid Day 30 June
… Local organizers are making final preparations for more than 50 public events worldwide to increase education and awareness about asteroids and how to better detect them. June 30 is the anniversary of the largest asteroid impact of Earth in recent history, the 1908 Siberian Tunguska asteroid impact. The 100X Declaration, calling for increased detection and tracking of near Earth objects, is open for public signature.
“Our surveillance of near-Earth objects is not good enough, so we are trying to ramp up the rate of detection by 100 times,” said astrophysicist and musician Brian May. “Signing the 100X Declaration is a way for the public to contribute to bringing about an awareness that we can protect humanity now and for future generations.”
More than 36 astronauts and cosmonauts are participating in Asteroid Day. A partial listing includes: Pedro Duque (Spain); Tamara Jernigan (U.S.); Tom Jones (U.S.); Alexei Leonov (Russia); Ed Lu (U.S.); Patrick Michel (France); Dorin Prunariu (Romania); Andres Eloy Martinez Rojas (Mexico); Franz Viehboeck (Austria); Rusty Schweickart (U.S.); and Anousheh Ansari (U.S.), the first woman private space traveler.
“If we can track the trajectories of asteroids and monitor their movement in our solar system, then we can know if they are on a path to impact Earth,” said Apollo astronaut Rusty Schweickart. “If we find them early enough, we can move them out of Earth’s orbit — thus preventing any kind of major natural disaster.”
Nature Article on Asteroid Surveys by Tracy Watson, 19 June 2015
Astronomy and science organizations have declared 30 June as Asteroid Day, with plans to talk up the danger of asteroids that might be on a collision course with Earth. One partner in the effort, the Sentinel mission, has an especially urgent need to drum up public support: it is struggling to raise the US$450 million it needs to launch a space telescope dedicated to finding hundreds of thousands of near-Earth objects.
Astronomers have long sought a spacecraft that would hunt for near-Earth objects full-time, but public funding for such a programme has never materialized. Ground-based surveys have identified nearly all of the largest asteroids, but many of the space rocks that measure between 50 and a few hundred metres in diameter — big enough to wipe out a city with a direct hit — remain uncharted.
“Without space-based assets, progress is going to stall,” says physicist Mark Boslough of Sandia National Laboratories in Albuquerque, New Mexico.
Sentinel, announced in 2012 by the B612 Foundation of Mill Valley, California, was supposed to provide that eye in the sky, and NASA had hoped that the privately run effort would supplement the agency’s own asteroid-hunting programme. NASA is considering funding an alternative mission, the Near-Earth Object Camera (NEOCam), initially proposed to the agency in 2006. But some scientists fear that Sentinel could spoil the chances of NASA supporting NEOCam. If Sentinel cannot fly, “then it’s just a distraction from getting a job done that needs to get done,” says planetary scientist Timothy Swindle of the University of Arizona in Tucson.
Ground-based surveys have located roughly 90% of the large asteroids that might be a concern — these are all bigger than one kilometre in diameter and pass by Earth’s orbit at a distance of 45 million kilometres or less. An impact by one of these behemoths would have global consequences; fortunately, such immense objects plummet to Earth on average only once every 700,000 years or so, and none of those known is heading this way any time soon.
The statistics are less reassuring for smaller objects. As of August 2014, according to data in a recent paper, surveys had spotted only 565 near-Earth asteroids ranging from roughly 45 to 55 metres across — out of an estimated total of up to 520,000 (A. W. Harris and G. D’Abramo Icarus 257, 302–312; 2015).……
Don’t fear apocalyptic asteroids: You’re safer than you think
New Scientist article by Jacob Aron, 22 June 2015:
…..Eric Christensen heads the Catalina Sky Survey, a NASA-funded initiative tasked with identifying potentially hazardous asteroids using sensitive ground-based telescopes. In the past decade or so, Catalina, other ground-surveys, and NASA’s WISE space telescope have spotted thousands of near-Earth objects (NEOs).
As you would expect, larger asteroids are easier to spot, but there are fewer of them. Surveys show that we have found nearly all of the potentially world-destroying asteroids – those larger than a kilometre – but many smaller objects remain uncatalogued.
Here’s how we know: astronomers can estimate how many asteroids of a given size are out there, even if we haven’t seen them all, by looking at the rate of re-detection, or how often we see the same asteroid a second time. If we consistently see the same set of kilometre-sized rocks, and no new ones, then we can be pretty sure we have found them all. “It’s probably going to be centuries before an asteroid like that hits over a populated area,” says Christensen. “If you go up to the size of a Tunguska impactor, the next one will likely hit us within a few centuries and impact over the ocean.”
So if we’re safe from the really big asteroids, and the smaller, more frequent ones are likely to hit without major incident, what’s the problem? It all depends on how much risk you’re willing to accept, and how much money you’re willing to spend to mitigate it….
Agencies, Hoping to Deflect Comets and Asteroids, Step Up Earth Defense
New York Times article by Bill Broad, 19 June 2015
The goal is to learn how to better deflect comets and asteroids that might one day endanger cities or the planet as a whole…..(Discusses the politics of the nuclear options)
NEO News (now in its twentieth year of distribution) is an informal compilation of news and opinion dealing with Near Earth Objects (NEOs) and their impacts. These opinions are the responsibility of the individual authors and do not represent the positions of NASA, Ames Research Center, the International Astronomical Union, NEOShield or any other organization. If anyone wishes to copy or redistribute original material from these notes, fully or in part, please include this disclaimer.