Asteroid measured when nudged by sunlight

   May 25, 5:51 pm

Washington, May 25 (ANI): NASA scientists have measured the orbit of asteroid, 1999 RQ36, with such accuracy that they were able to directly measure the drift resulting from a subtle but important force called the Yarkovsky effect - the slight push created when the asteroid absorbs sunlight and re-emits that energy as heat.

The scientists who made the measurement were on NASA's asteroid sample return mission, Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx).

"The new orbit for the half-kilometer (one-third mile) diameter 1999 RQ36 is the most precise asteroid orbit ever obtained," said OSIRIS-REx team member Steven Chesley of the NASA Jet Propulsion Laboratory, Pasadena, Calif.

Observations that Michael Nolan at Arecibo Observatory in Puerto Rico made in September 2011, along with Arecibo and Goldstone radar observations made in 1999 and 2005, when 1999 RQ36 passed much closer to Earth, show that the asteroid has deviated from its gravity-ruled orbit by roughly 100 miles, or 160 kilometers, in the last 12 years, a deviation caused by the Yarkovsky effect.

The Yarkovsky effect is named for the nineteenth-century Russian engineer who first proposed the idea that a small rocky space object would, over long periods of time, be noticeably nudged in its orbit by the slight push created when it absorbs sunlight and then re-emits that energy as heat.

Nolan and his team measured the distance between the Arecibo Observatory and 1999 RQ36 to an accuracy of 300 meters, or about a fifth of a mile, when the asteroid was 30 million kilometers, or 20 million miles, from Earth.

"That's like measuring the distance between New York City and Los Angeles to an accuracy of two inches, and fine enough that we have to take the size of the asteroid and of Arecibo Observatory into account when making the measurements," Nolan said.

Chesley and his colleagues used the new Arecibo measurements to calculate a series of 1999 RQ36 approaches closer to Earth than 7.5 million kilometers (4.6 million miles) from the years 1654 to 2135. There turned out to be 11 such encounters.

By combining the radar results from Arecibo Observatory with infrared results from NASA's Spitzer Space Telescope, the scientists also learned that asteroid 1999 RQ36 is very light - it has around the same density as water, Chesley reported.

"This study is an important step in better understanding the Yarkovsky effect - a subtle force that contributes to the orbital evolution of new Near-Earth Objects," said Dante Lauretta, the mission's principal investigator and professor of planetary science at the University of Arizona.

Lauretta added that "this information is critical for assessing the likelihood of an impact from our target asteroid and provides important constraints on its mass and density, allowing us to substantially improve our mission design."

The OSIRIS-REx spacecraft is to launch in 2016, reach asteroid (101955) 1999 RQ36 in 2019, examine it up close during a 505-day rendezvous, then return at least 60 grams (~1.9 ounces) of it to Earth in 2023.

"In addition to the exciting Yarkovsky results, the low density shows that 1999 RQ36 is probably a loose aggregate of rocks-a so called rubble pile. This makes it an ideal target for OSIRIS-REx to collect loose surface material," said Jason Dworkin, the mission's project scientist and Chief of Astrochemistry at NASA 's Goddard Space Flight Center in Greenbelt, Md.

The finding was presented recently at the Asteroids, Comets and Meteors 2012 meeting in Niigata, Japan. (ANI)

Jupiter's role as Earth's protector challenged Feb 4, 9:55 am
Washington D.C, Feb 4 (ANI): Since 1941, many astronomers have thought of Jupiter as a protective big brother for planet Earth, deflecting asteroids and comets away from the inner Solar System, and now, a new study has challenged its role as the celestial shield.
Full Story
Antarctic fungi survive Martian conditions Jan 29, 12:37 pm
Washington D.C, Jan 29 (ANI): The quest for life on Mars is as tantalizing as ever and now, an experiment conducted on the International Space Station has suggested that fungi and lichens may be able to survive on Mars.
Full Story
Monstrous cloud boomeranging back to Milky Way Jan 29, 10:38 am
Washington D.C, Jan 29 (ANI): A team of researchers has revealed that the old adage "what goes up must come down" is ringing true for an immense cloud of hydrogen gas that is heading towards our galaxy at nearly 700,000 miles per hour.
Full Story
Head-on collision with forming planet tugged the Moon out of Earth Jan 29, 8:56 am
Washington D.C, Jan 29 (ANI): When a "planetary embryo" called Theia collided with the early Earth approximately 100 million years after the Earth was formed, the moon span off into the orbit around the nascent planet, according to a new study.
Full Story
Comments