http://cornellsun.com/node/36816
On Feb. 28, sky-watchers at the Siding Spring Observatory in Australia sighted an unexpected guest: an asteroid heading directly toward the Earth. From the uncharted reaches of space, the asteroid zoomed toward the planet at 12 miles per second, forcing physicists to scramble for their calculators and crunch the numbers. Within minutes, the astronomers calculated the asteroid’s size, mass, speed and vector.

At approximately 69 ft. to 154 ft. in diameter, Asteroid 2009 DD45 posed a serious threat to the planet, and despite global surveillance, no one saw it coming. A similar asteroid destroyed 800 square miles of Siberian forest in the early twentieth century.

In response to similar near-Earth encounters, Congress is currently investigating the possibility of a new mandate that would require astronomers to identify and analyze all 140 meter near-Earth objects by 2020. The most recent Congressional mandate required astronomers to identify all 1000 meter near-Earth objects by 2012.

“In the future, we’re going to have hundreds of thousands to look at, but only thousands will be threatening,” explained Prof. Joseph Burns, planetary sciences.

According to Burns, in past years, similar asteroids repeatedly passed near the planet, but due to the development of modern surveying technology, scientists and politicians express increasing desire to identify possible threats.

“We have an incomplete sample of everything out there,” he said. “What we’re doing now is building a couple of large telescope systems.”

As Burns described, astronomers rely on two methods of surveillance: telescopes and spacecraft. Though costly, Burns explained, spacecraft surveillance provides indispensible accuracy and definition.

For instance, in conjunction with the Cassini Imaging Science Subsystem at NASA, Burns studies the characteristics of Saturn’s rings. Since 2004, the unmanned spacecraft Cassini has orbited the giant planet, taking detailed images of the rings and the stars. In that time, the images revealed the movement of the ring as Saturn rotates on its axis.

Last week, the position of Cassini, the sun, and the ring created a surprising image, showing that the outer layer of an inner ring forms an unexplained curve. Scientists believe the rings possess a consistent thickness of 10 meters, but these new images indicate an unexplained characteristic. With future images and research, Burns hopes to account for this fact.

“It’s like looking at a sunset,” he described. “The sun casts a shadow that reveals the vertical undulations of the ring.”

Due to Cassini’s optimal placement in orbit, the team surveyed an ambiguous structure.

However, due to the financial and technical limitations of space travel, astronomers rely upon optical, infrared, and radio telescopes to identify near-Earth objects.

“Short of spaceships, telescopes are the only way to get information,” explained Prof. Donald Campbell, radio and radar astronomy. Campbell is director of the Cornell’s National Astronomy and Ionosphere Center, which operates the Arecibo Observatory in Puerto Rico.

“It’s the world’s most powerful radar,” he said. “Optical telescopes cannot resolve these objects. It’s used for radio astronomy.”

The Arecibo telescope possesses a diameter of 305 meters and a depth of 51 meters, covering an area of 18 acres. Comprised of aluminum plates, the telescope sends pulses of energy in the form of radio wavelengths into space, detecting variations in spatial impact. These variations allow astronomer to construct multi-dimensional models of asteroids.

“We can measure the speed and velocity with great precision, which allows us to predict the orbit into the future,” he explained. “We can also make images of the object. It allows us a much greater understanding of the object.”

In 2007, as the National Science Foundation threatened to limit funding to Arecibo, Campbell testified before Congress, relating Arecibo’s continued importance toward identifying near-Earth objects.

“What they wanted to do was to reduce the cost, the level of funding,” he explained. “Arecibo is by far the best instrument on the planet to study near-Earth asteroids. If we lost funding it would be a tremendous loss for asteroid science.”

In recent years, global efforts have pushed to construct new telescopes, such as the Large Synoptic Survey Telescope.

“There’s a lot of activity going on in the area,” Campbell affirmed.

Stuff like this is why science funding and science education is so vital.