Astronomers Find That Space Rock Won't Hit Mars
UA telescopes and astronomers with follow-up observations

By Lori Stiles, University Communications
Jan. 11, 2008

Astronomers tracking asteroid 2007 WD5 with The University of Arizona Spacewatch Project on Kitt Peak, the UA/Smithsonian 6.5 meter MMT Observatory on Mount Hopkins and telescopes in New Mexico, Spain and Hawaii say chances that the asteroid will hit Mars at the end of January are nil.

Analysis of many tracking measurements of asteroid 2007 WD5 made by different observatories over the past few weeks shows the odds of a Mars impact are only one in 10,000, scientists with the NASA/Jet Propulsion Laboratory Near-Earth Object Program Office said Wednesday. Their news release is online.

Catalina Sky Survey team member Andrea Boattini discovered the asteroid with the UA's Mount Lemmon 60-inch telescope in the Santa Catalina Mountains north of Tucson on Nov. 20.

Follow-up observations, particularly those made at the Magdalena Ridge Observatory in New Mexico, on several crucial nights put the odds of impact with Mars at one in 75.

Astronomers, including several from the UA, have now provided more observational data for better information on the asteroid's orbit.

Terrence H. Bressi of Spacewatch on Kitt Peak provided follow-up with archival images from the 1.8-meter Spacewatch telescope. Catalina Sky Survey Director Steve Larson of the UA Lunar and Planetary Laboratory, MMT Observatory Director Faith Vilas and David Trilling of the UA Steward Observatory and others made follow-up observations with the MMT Observatory.

Teams in Spain, Hawaii and New Mexico also made follow-up observations.

"Our best estimate now is that 2007 WD5 will past about 26,000 kilometers (about 16,000 miles) from the planet's center at around 4 a.m. Pacific Standard Time on Jan. 30," NASA and JPL scientists said in a news release.

"The sequence of updates over the last few weeks has been typical of past potential impact scenarios, with the odds of impact initially surging and later plummeting towards zero," they said.

"The discovery of 2007 WD5, as well as the serendipitous recovery of the Rosetta Spacecraft that made a close gravity assist approach to the Earth recently, demonstrates that the current surveys continue to improve their detection efficiency," Larson said.

"It also indicates that there are probably many more objects that pass close to the Earth that are missed. However, if an impactor is discovered on the 'inbound,' there is little that can be done except to evacuate the expected impact area," he added. "The objective of the NEO surveys is to find potential impactors early – several decades early – so that some sort of mitigation scheme can be applied."

"It was gratifying to see how nicely coordinated the follow-up was, incorporating the contributions of multiple observatories to quickly determine the orbit, and future, of 2007 WD5 with outstanding precision," Catalina Sky Survey team member Ed Beshore said.