LOS ANGELES, Sept. 3 — NASA's Spitzer Space Telescope has found a mix of asteroids somewhat near Earth, termed near-Earth objects, the Jet Propulsion Laboratory (JPL) said on Thursday.
With a surprisingly wide array of compositions, these asteroids come in assorted colors and compositions, with some being dark and dull, and others shiny and bright, the JPL said.
The Spitzer observations of 100 known near-Earth asteroids demonstrate that the objects' diversity is greater than previously thought, said the JPL.
The findings will help astronomers better understand near-Earth objects as a whole — a population whose physical properties are not well known, the JPL noted.
"These rocks are teaching us about the places they come from," said David Trilling of Northern Arizona University, Flagstaff, lead author of a new paper on the research appearing in the September issue of Astronomical Journal. "It's like studying pebbles in a streambed to learn about the mountains they tumbled down."
After nearly six years of operation, in May 2009, Spitzer used up the liquid coolant needed to chill its infrared detectors. It is now operating in a so-called "warm" mode (the actual temperature is still quite cold at 30 Kelvin, or minus 406 degrees Fahrenheit). Two of Spitzer's infrared channels, the shortest- wavelength detectors on the observatory, are working perfectly.
One of the mission's new "warm" programs is to survey about 700 near-Earth objects, cataloguing their individual traits. By observing in infrared, Spitzer is helping to gather more accurate estimates of asteroids' compositions and sizes than what is possible with visible light alone.
Trilling and his team have analyzed preliminary data on 100 near-Earth asteroids so far. They plan to observe 600 more over the next year. There are roughly 7,000 known near-Earth objects out of a population expected to number in the tens to hundreds of thousands.
"Very little is known about the physical characteristics of the near-Earth population," said Trilling. "Our data will tell us more about the population, and how it changes from one object to the next. This information could be used to help plan possible future space missions to study a near-Earth object."
The JPL, headquartered in Pasadena, Los Angeles, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. (PNA/Xinhua)
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