Scientists at the University of Arizona welcome President Barack Obama's NASA budget proposal, rolled out this week, and specifically its focus on gaining a better understanding of asteroids that could potentially harm Earth.

The UA has a unique depth of capabilities and expertise that can help inform such missions and ensure their success. The UA is operating the most prolific ground-based system for identifying near-Earth asteroids, and it is tasked by NASA with leading a spacecraft mission to retrieve a sample from an asteroid.

Expected to launch in 2016, NASA's OSIRIS-REx mission will travel to near-Earth asteroid 1999 RQ36, study it for a year with a variety of instruments, collect a sample and return it to Earth in 2023.

Science operations will be performed on the UA campus; University scientists and engineers will build the camera suite for the spacecraft and will engage in education and outreach.

Measuring more than 1,600 feet in diameter, the OSIRIS-REx target asteroid is a uniquely interesting scientific target, while at the same time one of the most potentially hazardous objects known, with a one in 2,000 chance of colliding with Earth in the late 22nd century.

Dante Lauretta, principal investigator for the OSIRIS-REx mission and a faculty member at UA's Lunar and Planetary Laboratory, or LPL, said, "Much of what we have developed over many years of ground-based asteroid discovery, follow-up characterization, and research into the very basic nature of asteroids and how they behave paves the way for NASA's exploration of these fascinating and important solar system objects."

On OSIRIS-REx, the UA has partnered with the NASA Goddard Space Flight Center in Greenbelt, Md., which will manage the mission, and Lockheed Martin Space Systems in Littleton, Colo., which will build and operate the spacecraft.

"Planning an asteroid mission begins with selecting a suitable target," said Ed Beshore, deputy principal investigator for the OSIRIS-REx mission at LPL.

"Before we can even think about going, we need to understand everything we possibly can about that object using ground- and space-based telescopes and radar instruments, to ensure the success of a space mission."

Discovering and studying a suitable target is a core expertise of the UA, Beshore added.

The first search using modern detection methods began with Spacewatch, a UA asteroid survey, in the early 1980s, founded by the late Tom Gehrels, a UA professor at LPL who was among the first to advocate for a systematic search for asteroids that could pose a collision threat to Earth.

The Catalina Sky Survey, or CSS, also a UA program, began its program of search in 2003, and today, remains the most productive asteroid-discovery program operating, finding more than 65 percent of all near-Earth objects discovered in 2012.

The mission of the Catalina Sky Survey is to contribute to the inventory of near-Earth objects, with particular focus on the potentially hazardous asteroids that pose an impact risk to Earth and its inhabitants. During the first half of 2012, CSS discovered more than 350 near-Earth asteroids, including nine of diameter 1 kilometer or more.

Given that the asteroid that recently exploded over Russia with an energy level exceeding 470 kilotons had a diameter of just 17 meters, it is clear that the largest asteroids are very dangerous objects.

The NASA Near-Earth Object Observations Program, or NEOO, is a result of a 1998 congressional directive to identify 90 percent of all 1 kilometer or larger bodies.

Since 2005, CSS has been by far the most prolific discoverer of near-Earth objects among NEOO participants. The Catalina Survey was instrumental in NASA's successful program, and the success of NASA's mission hasn't stopped with these largest objects - about half of the objects larger than 300 meters have been discovered as well.

Through extensive study of meteorites, which are essentially fragments of asteroids that fell to the Earth's surface, UA scientists have been able to formulate leading theories of asteroid formation, composition and their role in answering the important questions of the source of water and organics that may have seeded life on Earth.

In preparation for its 2018 encounter with asteroid 1999 RQ36, the UA has carefully selected the OSIRIS-REx target asteroid for maximum scientific value, and has conducted extensive multi-year studies of that asteroid using ground- and space-based telescopes. All of this effort has resulted in a spacecraft and instrument suite that has high probability of success in meeting its goal.