Space

May 31, 2013

NASA’S WISE mission finds lost asteroid family members

Data from NASA’s Wide-field Infrared Survey Explorer have led to a new and improved family tree for asteroids in the main belt between Mars and Jupiter.

Astronomers used millions of infrared snapshots from the asteroid-hunting portion of the WISE all-sky survey, called NEOWISE, to identify 28 new asteroid families. The snapshots also helped place thousands of previously hidden and uncategorized asteroids into families for the first time. The findings are a critical step in understanding the origins of asteroid families, and the collisions thought to have created these rocky clans.

“NEOWISE has given us the data for a much more detailed look at the evolution of asteroids throughout the solar system,” said Lindley Johnson, the program executive for the Near-Earth Object Observation Program at NASA Headquarters in Washington. “This will help us trace the NEOs back to their sources and understand how some of them have migrated to orbits hazardous to the Earth.”

The main asteroid belt is a major source of near-Earth objects (NEOs), which are those asteroids and comets that come within 28 million miles (45 million kilometers) of Earth’s path around the sun. Some near-Earth objects start out in stable orbits in the main asteroid belt, until a collision or gravitational disturbance flings them inward like flippers in a game of pinball.

The NEOWISE team looked at about 120,000 main belt asteroids out of the approximately 600,000 known. They found that about 38,000 of these objects, roughly one third of the observed population, could be assigned to 76 families, 28 of which are new. In addition, some asteroids thought to belong to a particular family were reclassified.

An asteroid family is formed when a collision breaks apart a large parent body into fragments of various sizes. Some collisions leave giant craters. For example, the asteroid Vesta’s southern hemisphere was excavated by two large impacts. Other smash-ups are catastrophic, shattering an object into numerous fragments, as was the case with the Eos asteroid family. The cast-off pieces move together in packs, traveling on the same path around the sun, but over time the pieces become more and more spread out.

Previous knowledge of asteroid family lineages comes from observations of their orbits. NEOWISE also looked at the asteroids’ reflectivity to identify family members.

Asteroids in the same family generally have similar mineral composition and reflect similar amounts of light. Some families consist of darker-colored, or duller, asteroids, while others are made up of lighter-colored, or shinier, rocks. It is difficult to distinguish between dark and light asteroids in visible light. A large, dull asteroid can appear the same as a small, shiny one. The dark asteroid reflects less light but has more total surface area, so it appears brighter.

NEOWISE could distinguish between the dark and light asteroids because it can detect infrared light, which reveals the heat of an object. The larger the object, the more heat it gives off. When the size of an asteroid can be measured, its true reflective properties can be determined, and a group of asteroids once thought to belong to a single family circling the sun in a similar orbit can be sorted into distinct families.

“We’re separating zebras from the gazelles,” said Joseph Masiero of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif., who is lead author of a report on the new study that appears in the Astrophysical Journal. “Before, family members were harder to tell apart because they were traveling in nearby packs. But now we have a better idea of which asteroid belongs to which family.”

The next step for the team is to learn more about the original parent bodies that spawned the families.

“It’s as if you have shards from a broken vase, and you want to put it Back together to find out what happened,” said Amy Mainzer, the NEOWISE principal investigator at JPL. “Why did the asteroid belt

form in the first place and fail to become a planet? We are piecing together our asteroids’ history.”

JPL, a division of the California of Technology in Pasadena, managed and operated WISE for NASA’s Science Mission Directorate. The spacecraft was put into hibernation mode in 2011, after completing its main objectives of scanning the entire sky twice.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines August 31, 2015

News: Pilot killed in crash was helping wounded veterans – A pilot who died in a small plane crash in the desert northeast of Los Angeles was giving free glider rides to wounded military veterans. Turkey carries out first air strikes as part of anti-Isis U.S. coalition – Turkish fighter jets have carried out their first air...
 
 

News Briefs August 31, 2015

Pakistan officials: U.S. envoy discusses Afghan peace efforts Pakistani officials say visiting U.S. National Security Adviser Susan Rice has discussed efforts to revive Afghan peace talks. Rice met with Prime Minister Nawaz Sharif and army chief Gen. Raheel Sharif Aug. 30. Two Pakistani officials say they discussed efforts to revive talks between the Afghan government...
 
 
Courtesy photograph

F-22 inaugural deployment to Europe

Courtesy photograph A pair of F-22 Raptors fly near the coastline of Panama City Beach, Fla. Four F-22 Raptors, one C-17 Globemaster III, and approximately 60 airmen arrived at Spangdahlem Air Base, Germany, to train with allie...
 

 
ILS photograph

Boeing-built satellite will create first global high-speed broadband network

ILS photograph The Inmarsat-5 F3 satellite launched Aug. 28 aboard a International Launch Services Proton Breeze M rocket from Baikonur, Kazakhstan. EL SEGUNDO, Calif.–When the third Boeing-built [NYSE: BA] Inmarsat-5 sat...
 
 

Civil Air Patrol joins total force ‘Airmen’

When conducting missions for the Air Force as the official Air Force auxiliary, the Civil Air Patrol is now included in the Air Force’s definition of the total force. CAP has provided 74 years of support to emergency services, aerospace education and cadet programs. In August 2015, the Air Force updated Doctrine Volume 2, “Leadership,”...
 
 
DOD photograph by Air Force MSgt. Adrian Cadiz

Carter announces manufacturing initiative to aid war fighters

DOD photograph by Air Force MSgt. Adrian Cadiz Defense Secretary Ash Carter announces the creation of a National Manufacturing Innovation Institute to produce hybrid electronics during a speech at the National Full Scale Aerody...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>