In the 1970s Walter Alvarez, a professor in the Earth and Planetary Science department at the University of California, Berkeley started to form a hypothesis connecting an asteroid impact, the presence of its global Iridium layer in the rock strata, and the loss of the dinosaurs in what has become known as the Cretaceous–Tertiary (or K-T) mass extinction event.
Verified by geological dating, the location of the asteroid’s impact crater was eventually discovered at Chicxulub, in the Yucatán Peninsula. The now confirmed scientific theory made truly shocking reading. It stated that 66 million years ago, our planet was hit by a space rock 10kms in diameter traveling at 40,000kph. Taking two seconds to traverse the atmosphere it buried itself kilometres deep in the Earth’s crust, with resultant molten ejecta traversing the entire globe. Worldwide cataclysmic fires created dense and choking dust and smoke that blocked out most sunlight for years. Temperatures plummeted, and 75% of all species on Earth, including dinosaurs became extinct. In this epic catastrophe, small dinosaurs capable of flight survived to become modern day birds. Tiny underground shrew-like animals that lived on roots also survived.
In terms of longevity of their reign of over 150 million years, the dinosaurs are to this day the most successful creatures ever to walk the Earth. Their sudden demise however, ushered in the age of the mammals that would one day evolve into us. Without the Chicxulub impact, debatably the most intelligent species ever seen on Earth i.e. ‘us’ simply wouldn’t exist. Mammals truly did inherit the Earth.
Sounds like great news? Well, it isn’t. Further research proved these apocalyptic events have happened repeatedly during the Earth’s 4.5 billion year history, and will happen again. And you can prove it to yourself by looking at the Moon through binoculars. Without terrestrial weathering and geological erosion processes, its pristine surface reveals a horrifying and perfect record of this continuing routine planetary violence. It’s covered with craters and some like Tycho and Copernicus dwarf the terrestrial Yucatán impact site.
Working in unison the shocking question agencies such as NASA and the Planetary Society are asking is not “if” such an event will be repeated but “when”. Another such agency is the B612 Foundation. Its raison d’etre is to alter the orbit of one of these Potentially Hazardous Asteroids or PHAs in a controlled manner in a project it has called Sentinel.
As a first step it plans to launch a space telescope specialising in the infra-red spectrum, a form of light that asteroids emit in copious quantities. Launched atop a Space X Falcon 9 booster it would reside in an orbit of the Sun close to Venus, and would catalogue 90% of asteroids with diameters larger than 140 metres. It is expected to be launched by 2020. This private project has evolved out of NASA’s Johnson Space Centre and is led by NASA’s Rusty Schweickart and Ed Lu along with Clark Chapman. It is currently raising the $450 million needed to meet this aim.
In early 2013 a 20 metres-diameter asteroid entered the Earth’s atmosphere, becoming a brilliant super bolide meteor before exploding in an air burst over Chelyabinsk, Russia, at a height of 23 kilometres. The resultant public concern at this event resulted in a surge of interest in projects such as Sentinel that are designed to detect PHAs before they impact the Earth.
As an intelligent species we can at present control only one form of natural disaster: asteroid impacts. Given enough lead time before forecasted impact we have, should we choose to use it, the ability to deflect these doomsday objects. The key point here is “enough lead time” because the realistic methods available include human-induced gravity, or the use of reflected sunlight in photon pressure (in other words the pressure of light waves). These both cause minute changes in the trajectory of these PHAs, changes that over years will result in slightly different orbits that are enough to save the Earth from a devastating impact.
The question is: will we invest in such planet-saving technology or will we suffer the fate of the dinosaurs. T Rex had an excuse for its extinction due to its lack of intelligence. We don’t.
Useful Information about PHAs
B612 Foundation: www.b612foundation.org
Potential future Earth impact events from JPL Sentry: http://neo.jpl.nasa.gov/risk/
Discovery of the PHA threat: T.Rex and the Crater of Doom by Walter Alvarez, Princeton University Press, 2008. Paperback ISBN13: 9780691131030.
Asteroid FAQs: Did You Know they’re so important they’re discussed at the White House?
At the beginning of June 2013, the White House held a 45 minute long Google hang-out with Lori Garver, Deputy Administrator of NASA, Bill Nye the Science Guy and CEO of the Planetary Society, and Ed Lu, founder member of the B612 Foundation, American physicist and former NASA astronaut.
The subject was asteroid 1998QE2. It is a PHA 2.7km in diameter and it’s extraordinary as it possesses its own small moon, which is a tiny asteroid actually orbiting it! Terrifyingly this PHA came within just fifteen lunar diameter widths, or 52,000 kms of our planetary home, the Earth. Passing between us and the Moon, this is just 12.5% of the distance that NASA’s Apollo astronauts traveled on the way to the Earth’s natural satellite! And although a quarter of the diameter, it was traveling at the same speed as the impactor that caused the KT extinction event!