By Kenneth Martin

Potential Future Earth Impact

73 NEAs: Last Updated Jul 08, 2005

The following table lists potential future Earth impact events that the JPL Sentry System has detected based on currently available observations. Click on the object designation to go to a page with full details on that object.

Sentry is a highly automated collision monitoring system that continually scans the most current asteroid catalog for possibilities of future impact with Earth over the next 100 years. Whenever a potential impact is detected it will be analyzed and the results immediately published here, except in unusual cases where an IAU Technical Review is underway. For more information on impact monitoring and risk assessment see our Impact Risk Introduction and Frequently Asked Impact Risk Questions.

It is normal that, as additional observations become available, objects will disappear from this table whenever there are no longer any potential impact detections. For this reason we maintain a list of removed objects with the date of removal.

Potentially Hazardous Asteroids

PHA Close Approaches To The Earth

The following table lists the predicted encounters by Potentially Hazardous Asteroids (PHAs) to within 0.05 AU of the earth from the start of this year through 2178. Objects with very uncertain orbits are excluded from this listing, as are recently discovered objects whose orbits have been computed without consideration of planetary perturbations. The distances quoted are from the nominal orbit solutions in the cited references and can be quite uncertain, particularly for one-opposition objects. Perturbed orbital solutions consider perturbations by eight major planets (Mercury to Neptune), three minor planets (Ceres, Pallas and Vesta) and treat the earth and the moon as separate perturbing bodies. For comparison, the mean distance of the moon is 0.0026 AU = 384400 km = 238900 miles. (1 AU is approximately the mean distance of the earth from the sun = 149597870 km = 92955810 miles.)

http://www.jpl.nasa.gov/releases/2000/neat.html

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Contact: Jane Platt (818) 354-0880

FOR IMMEDIATE RELEASE January 12, 2000

ASTEROID POPULATION COUNT SLASHED

       NASA scientists taking a census of large asteroids in our solar system neighborhood have cut their estimate in half.

       The revised calculation comes from data gathered by NASA's Near-Earth Asteroid Tracking System (NEAT) and published in the January 13 issue of the journal Nature.

       "Until now, scientists thought the population of large, near-Earth asteroids was between 1,000 and 2,000, but we've downgraded that figure significantly," said Dr. David Rabinowitz, of Yale University, New Haven, CT, lead author of the article and NEAT co-investigator. "We now believe there are between 500 and 1,000 near-Earth asteroids larger than one kilometer (about 0.6 miles) in diameter."

       "This newer estimate was made possible by the computerized technology of the NEAT camera," Rabinowitz said. The NASA-funded system began tracking near-Earth asteroids and comets in 1995 with a charge-coupled device camera mounted on a 1-meter (39- inch) Air Force telescope atop Mount Haleakala on Maui, HI.

       The new figures may represent good news in the quest to achieve NASA's stated goal of finding 90-percent of all large, near-Earth asteroids by 2010, according to NEAT project manager Dr. Steven Pravdo of NASA's Jet Propulsion Laboratory, Pasadena, CA, a co-author of the Nature article.

       "Right now we know of 322 large, near-Earth asteroids," Pravdo said. "That was a fairly small fraction of the 2,000 asteroids in our previous estimate. With our new calculations of between 500 and 1,000 such objects, this 322 figure represents a large chunk."

       While stressing that we must learn more about potential hazards from asteroids, Rabinowitz said, "None of the asteroids we've observed will hit Earth anytime in the near future."

       "This new analysis reduces by half the estimated number of these potential hazards to Earth," Pravdo said.

       "In the past, we relied on humans poring over photographic plates of the nighttime sky," Rabinowitz said. "The problem was, they didn't know how many asteroids they were missing, because they couldn't see faint objects. People's eyes also became tired and teary and they overlooked some objects. Machines don't get tired."

       "With this computerized technology, we can find asteroids more easily and count them more accurately," Pravdo said. "It's important to know your observational limits, and with that information, we can develop models for what we are not able to see. This makes our estimates even more accurate."

       Additional co-authors on the Nature article are Eleanor Helin of JPL, NEAT principal investigator, and Kenneth Lawrence, also of JPL. Helin was also principal investigator of the Palomar Planet-Crossing Asteroid Survey, a photographic search program, conducted for almost 25 years until it was discontinued and replaced by NEAT, the electronic detection program, in 1995. Her efforts were key to the organization of the NEAT program.

       Data gathered by the asteroid tracking system are processed at Haleakala, and then undergo post-processing and analysis at JPL. This latest asteroid estimate is based on data collected between 1995 and 1998.

       The asteroid tracking system has been on hiatus for the past year, but plans are in the works to re-activate the system in February using an upgraded 1.2-meter (48-inch) Air Force telescope on Haleakala. In addition, later this year, NEAT scientists will begin using the 1.2-meter (48-inch) Oschin telescope at Palomar Observatory near San Diego, CA.

       Additional information on the NEAT project is available at http://neat.jpl.nasa.gov . Information on near-Earth objects is available at http://neo.jpl.nasa.gov .

       The Near Earth Asteroid Tracking System is managed for NASA's Office of Space Science, Washington, D.C. by JPL, a division of the California Institute of Technology, Pasadena, CA..

http://neo.jpl.nasa.gov/

NASA's Deep Impact Generates Its Own Spectacular Photo Flash

July 4, 2005

The hyper-speed demise of NASA's Deep Impact probe generated an immense flash of light, which provided an excellent light source for the two cameras on the Deep Impact mothership. Deep Impact scientists theorize the 820-pound impactor vaporized deep below the comet's surface when the two collided at 1:52 am July 4, at a speed of about 10 kilometers per second (6.3 miles per second or 23,000 miles per hour).

"You can not help but get a big flash when objects meet at 23,000 miles per hour," said Deep Impact co-investigator Dr. Pete Schultz of Brown University, Providence, R.I. "The heat produced by impact was at least several thousand degrees Kelvin and at that extreme temperature just about any material begins to glow. Essentially, we generated our own incandescent photo flash for less than a second."

http://deepimpact.jpl.nasa.gov/press/050704a-jpl.html

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

DC Agle (818) 393-9011
Jet Propulsion Laboratory, Pasadena, Calif.

Dolores Beasley (202) 358-1753
NASA Headquarters, Washington

Lee Tune (301) 405-4679
University of Maryland, College Park

RELEASE: 2005-110

NASA'S DEEP IMPACT GENERATES ITS OWN SPECTACULAR PHOTO FLASH

The hyper-speed demise of NASA's Deep Impact probe generated an immense flash of light, which provided an excellent light source for the two cameras on the Deep Impact mothership. Deep Impact scientists theorize the 820-pound impactor vaporized deep below the comet's surface when the two collided at 1:52 am July 4, at a speed of about 10 kilometers per second (6.3 miles per second or 23,000 miles per hour).

"You can not help but get a big flash when objects meet at 23,000 miles per hour," said Deep Impact co-investigator Dr. Pete Schultz of Brown University, Providence, R.I. "The heat produced by impact was at least several thousand kelvin and at that extreme temperature just about any material begins to glow. Essentially, we generated our own incandescent photo flash for less than a second."

The flash created by the impact was just one of the visual surprises that confronted the Deep Impact team. Preliminary assessment of the images and data downlinked from the flyby spacecraft have provided an amazing glimpse into the life of a comet.

"They say a picture can speak a thousand words," said Deep Impact Project Manager Rick Grammier of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "But when you take a look at some of the ones we captured in the early morning hours of July 4, 2005 I think you can write a whole encyclopedia."

At a news conference held later on July 4, Deep Impact team members displayed a movie depicting the final moments of the impactor's life. The final image from the impactor was transmitted from the short-lived probe three seconds before it met its fiery end.

"The final image was taken from a distance of about 30 kilometers (18.6 miles) from the comet's surface," said Deep Impact Principal Investigator Dr. Michael A'Hearn of the University of Maryland, College Park. "From that close distance we can resolve features on the surface that are less than 4 meters (about 13 feet) across. When I signed on for this mission I wanted to get a close-up look at a comet, but this is ridiculous? in a great way."

The Deep Impact scientists are not the only ones taking a close look at their collected data. The mission's flight controller team is analyzing the impactor's final hours of flight. When the real-time telemetry came in after the impactor's first rocket firing, it showed the impactor moving away from the comet's path.

"It is fair to say we were monitoring the flight path of the impactor pretty closely," said Deep Impact navigator Shyam Bhaskaran of JPL. "Due to the flight software program, this initial maneuver moved us seven kilometers off course. This was not unexpected but at the same time not something we hoped to see. But then the second and third maneuvers put us right where we wanted to be."

The Deep Impact mission was implemented to provide a glimpse beneath the surface of a comet, where material from the solar system's formation remains relatively unchanged. Mission scientists hoped the project would answer basic questions about how the solar system formed, by providing an in-depth picture of the nature and composition of the frozen celestial travelers known as comets.

The University of Maryland is responsible for overall Deep Impact mission science, and project management is handled by JPL. The spacecraft was built for NASA by Ball Aerospace & Technologies Corporation, Boulder, Colo.