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.


 
 

 

News Briefs February 27, 2015

Ukraine will start pulling back heavy weapons in the east Ukraine’s military says it will start pulling back its heavy weapons from the front line with Russian-backed separatists as required under a cease-fire agreement. The Defense Ministry said in a statement Feb. 26 that it reserved the right to revise its withdrawal plans in the...
 
 

Northrop Grumman’s AstroMesh reflector successfully deploys for NASA’s SMAP satellite

The NASA Jet Propulsion Laboratory successfully deployed the mesh reflector and boom aboard the Soil Moisture Active Passive spacecraft, a key milestone on its mission to provide global measurements of soil moisture. Launched Jan. 31, SMAP represents the future of Earth Science by helping researchers better understand our planet. SMAP’s unmatched data capabilities are enabled...
 
 
NASA photograph by Brian Tietz

NASA offers space tech grants to early career university faculty

NASA photograph by Brian Tietz Tensegrity research is able to simulate multiple forms of locomotion. In this image, a prototype tensegrity robot reproduces forward crawling motion. NASA’s Space Technology Mission Director...
 

 
navy-china

USS Fort Worth conducts CUES with Chinese Navy

The littoral combat ship USS Fort Worth (LCS 3) practiced the Code for Unplanned Encounters at Sea (CUES) with the People’s Liberation Army-Navy Jiangkai II frigate Hengshui (FFG 572) Feb. 23 enhancing the professional ma...
 
 

AEGIS tracks, simulates engagement of three short-range ballistic missiles

The Missile Defense Agency and sailors aboard the guided-missile destroyers USS Carney (DDG 64), USS Gonzalez (DDG 66), and USS Barry (DDG 52) successfully completed a flight test involving the Aegis Ballistic Missile Defense weapon system. At approximately 2:30 a.m., EST, Feb. 26, three short-range ballistic missile targets were launched near simultaneously from NASA’s Wallops...
 
 

DOD seeks novel ideas to shape its technological future

The Defense Department is seeking novel ideas to shape its future, and officials are looking to industry, small business, academia, start-ups, the public – anyone, really – to boost its ability to prevail against adversaries whose access to technology grows daily. The program, called the Long-Range Research and Development Plan, or LRRDP, began with an...
 




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=""> <strike> <strong>