Target Earth: How Prepared Are We?

It exploded over Siberia – this object from space – and leveled 2,000 square kilometers of forest, flattening pine trees like matchsticks. June 30 marks the 100th anniversary of the Tunguska event, the day in 1908 when an asteroid or comet entered Earth’s atmosphere and, in effect, fired an astronomical warning shot across our bow. How prepared is Earth today to avoid disaster from the skies?

The dangers our planet faces from near-Earth objects (NEOs) are the focus of The Planetary Society's new program, Target Earth. The effort includes the Apophis Mission Design Competition; a campaign to save the Arecibo telescope’s radar tracking of NEOs; and the newest call for proposals for the Society’s Gene Shoemaker Near-Earth Object Grants.

“We live in a busy solar system,” said Louis Friedman, Executive Director of The Planetary Society. “Finding and tracking all the NEOs that might intersect Earth’s orbit beats yelling, ‘Duck!’ when the next impactor comes our way.”

GENE SHOEMAKER NEAR-EARTH OBJECT GRANTS

Today – unlike 100 years ago – we can spot incoming objects and determine their orbits to learn if any might be on its way to collide with Earth. To that end, The Planetary Society created the Gene Shoemaker Near-Earth Object Grant program to support amateur observers, observers in developing countries, and professional astronomers who, with seed funding, can greatly contribute to NEO research.

After pioneering scientist Gene Shoemaker’s death in 1997, The Planetary Society created the program in honor of Shoemaker, a man who led the study of impact structures and advocated stepped-up NEO discovery and tracking programs. To date, the Society has awarded 29 Shoemaker NEO Grants, totaling more than $184,000, to observers around the world.

Shoemaker grant winners have discovered hundreds of asteroids, among them several near-Earth objects. One of these is Roy Tucker’s co-discovery of Apophis, a NEO that has garnered great public attention because it has a small chance of impacting Earth within a few decades. Shoemaker grant winners have also provided crucial tracking data for numerous objects that pass through Earth’s neighborhood in space.

Two 2007 award winners worked together in the discovery and follow up observations of near-Earth object 2007 NL1. Quan-zhi Ye from mainland China – remotely operating a telescope at Lulin Observatory in Taiwan – discovered this asteroid, then asked fellow grant winner, Jean-Claude Pelle in Tahiti, to track it so that its orbit could be pinned down. Pelle was able to succeed when other observatories were clouded out.

A 2005 grant recipient, David Higgins, discovered that a previously known asteroid, (6084) Bascom, is actually a binary (two objects orbiting the Sun together).

Shoemaker NEO Grant winners have contributed tens of thousands of observational measurements used to define the exact orbits of NEOs to help determine if they are a threat to Earth. They are also helping to understand the physical characteristics of NEOs, which will be critical for any future efforts to deflect them from striking Earth.

The deadline to apply for 2008 Shoemaker NEO Grants is September 30, 2008.

TUNGUSKA

The fireball that laid waste a vast swath of forest near the Podkamennaya Tunguska River in Russia was most likely an asteroid that exploded before it reached the ground. Such an explosion today over New York, Paris or Beijing could level the entire city, killing millions.

Recent scientific studies have downsized the object responsible for the Tunguska cataclysm, increasing the chances that such an impact could occur in the future since smaller asteroids far outnumber the larger ones that orbit near Earth.

APOPHIS COMPETITION

In February 2008, the Society announced the winners of its $50,000 Apophis Mission Design Competition, which invited participants to propose the best way to rendezvous with and "tag" a potentially dangerous near-Earth object. By tagging an asteroid, scientists can track it accurately enough to determine whether it will impact Earth, thus helping space agencies to decide whether to mount a deflection mission to alter its orbit.

The $50,000 in prize money for the Apophis Mission Design Competition was contributed by The Planetary Society's Chairman of the Board, Dan Geraci. Additional funding to run the competition was provided by Planetary Society members around the world. The competition received 37 mission proposals from 19 countries on 6 continents.

The Society has also contributed to Discovery Canada's “Asteroid Trackers,” a one-hour HD TV “Daily Planet” special on asteroids, slated to air on June 30.

Since The Planetary Society's inception in 1980, the organization has donated well over a quarter million dollars to asteroid research, more than half of which was awarded through Gene Shoemaker Near-Earth Object Grants.