A NASA-sponsored asteroid tracking system has found two new large objects that cross Earth's orbital path, but show no signs of coming dangerously close to Earth within at least the next several decades, astronomers say.
The asteroids were found in observations made with the Near- Earth Asteroid Tracking (NEAT) system, managed by NASA's Jet Propulsion Laboratory, Pasadena, CA.
"These discoveries come on the heels of last month's installation of new state-of-the-art computing and data analysis hardware that speeds our search for near-Earth objects," said NEAT Project Manager Dr. Steven Pravdo of JPL. "This shows that our efforts to find near-Earth objects are paying off."
The newly discovered asteroids 1998 OH and 1998 OR2 are both large enough to cause global effects if one impacted Earth, and both are classified as "potentially hazardous objects" because they pass periodically near Earth's orbit (like at least 125 other objects discovered so far). Both asteroids are 1 to 3 kilometers (about 1 mile) in diameter.
Crucial follow-up observations of both asteroids made by co- investigator Dr. David L. Rabinowitz of JPL were used to calculate projected orbits that show that neither of the objects pose an immediate threat to Earth. Rabinowitz made the observations with the 61-centimeter (24-inch) telescope at the JPL's Table Mountain Facility in Wrightwood, CA, which is used to make immediate follow-up observations of recently discovered near-Earth objects in an effort to better determine their orbits, compositions and rotational state.
"Our goal is to discover and track all the potentially dangerous asteroids and comets long before they are likely to approach Earth," said NEAT Principal Investigator Eleanor Helin. "The discovery of these two asteroids illustrates how NEAT is doing precisely what it is supposed to do."
Additional follow-up observations are required to more precisely determine the orbits of these asteroids, but preliminary projections show that 1998 OH can get no closer than about 5 million kilometers (about 3 million miles) -- about 12 times the distance between Earth and the Moon.
NEAT uses a large, sensitive and fully automated charge- coupled device (CCD) camera mounted on a 1-meter-diameter (39- inch) telescope operated by the U.S. Air Force at the 3,000-meter (9,000-foot) summit of Mt. Haleakela on the island of Maui in Hawaii. "Our upgraded equipment has speeded up the data processing allowing us to analyze up to 40 gigabytes of data each night, equivalent to 1,200 images of the sky," said Pravdo.
Images and other information about the new asteroids and the NEAT project can be found on the Internet at http://huey.jpl.nasa.gov/~spravdo/neat.html .