WISE mission finds lost asteroid family members

May 30, 2013
This artist's conception shows how families of asteroids are created. Over the history of our solar system, catastrophic collisions between asteroids located in the belt between Mars and Jupiter have formed families of objects on similar orbits around the sun. Image credit: NASA/JPL-Caltech

(Phys.org) —Data from NASA's Wide-field Infrared Survey Explorer (WISE) 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 -hunting portion of the WISE all-, 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 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 , 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 '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 could detct 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 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 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."

Explore further: First potentially habitable Earth-sized planet confirmed: It may have liquid water

More information: Paper: dx.doi.org/10.1088/0004-637X/770/1/7

Related Stories

Origin of dinosaur-killing asteroid remains a mystery

Sep 20, 2011

(PhysOrg.com) -- Observations from NASA's Wide-field Infrared Survey Explorer (WISE) mission indicate the family of asteroids some believed was responsible for the demise of the dinosaurs is not likely the ...

The hustle and bustle of our solar system

Jul 31, 2012

(Phys.org) -- This diagram illustrates the differences between orbits of a typical near-Earth asteroid (blue) and a potentially hazardous asteroid, or PHA (orange). PHAs are a subset of the near-Earth asteroids ...

NASA's NEOWISE completes scan for asteroids and comets

Feb 01, 2011

(PhysOrg.com) -- NASA's NEOWISE mission has completed its survey of small bodies, asteroids and comets, in our solar system. The mission's discoveries of previously unknown objects include 20 comets, more ...

WISE mission finds fewer asteroids near Earth

Sep 29, 2011

(PhysOrg.com) -- New observations by NASA's Wide-field Infrared Survey Explorer, or WISE, show there are significantly fewer near-Earth asteroids in the mid-size range than previously thought. The findings ...

NASA survey counts potentially hazardous asteroids

May 17, 2012

(Phys.org) -- Observations from NASA's Wide-field Infrared Survey Explorer (WISE) have led to the best assessment yet of our solar system's population of potentially hazardous asteroids. The results reveal ...

Recommended for you

Exoplanets soon to gleam in the eye of NESSI

2 hours ago

(Phys.org) —The New Mexico Exoplanet Spectroscopic Survey Instrument (NESSI) will soon get its first "taste" of exoplanets, helping astronomers decipher their chemical composition. Exoplanets are planets ...

A sharp eye on Southern binary stars

23 hours ago

Unlike our sun, with its retinue of orbiting planets, many stars in the sky orbit around a second star. These binary stars, with orbital periods ranging from days to centuries, have long been the primary ...

Hubble image: A cross-section of the universe

23 hours ago

An image of a galaxy cluster taken by the NASA/ESA Hubble Space Telescope gives a remarkable cross-section of the Universe, showing objects at different distances and stages in cosmic history. They range ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Requiem
1.8 / 5 (5) May 30, 2013
From the article, 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."

--

Doesn't a basic newtonian model, completed in minutes, seconds or milliseconds on a 486DX, show that with something like Jupiter where it is, it is simply impossible for a planet to accrete where the asteroid belt is...?

More news stories

Ceres and Vesta Converge in Virgo

Don't let them pass you by. Right now and continuing through July, the biggest and brightest asteroids will be running on nearly parallel tracks in the constellation Virgo and so close together they'll easily ...

LADEE mission ends with planned lunar impact

(Phys.org) —Ground controllers at NASA's Ames Research Center in Moffett Field, Calif., have confirmed that NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft impacted the surface ...

Could 'Jedi Putter' be the force golfers need?

Putting is arguably the most important skill in golf; in fact, it's been described as a game within a game. Now a team of Rice engineering students has devised a training putter that offers golfers audio, ...