JPL
Careers
Education
Science & Technology
JPL Logo
JPL Logo
Solar System
.

Tracking A Mysterious Group of Asteroid Outcasts

Aug 03, 2015
The asteroid Euphrosyne glides across a field of background stars in this time-lapse view from NASA's WISE spacecraft. › Full image and caption

Astronomers may have found the source of a particularly hard-to-spot group of near-Earth asteroids, thanks to a once-dormant NASA space telescope.

Fast Facts:

› A new NASA study has traced some members of the near-Earth asteroid population back to their likely source.

› The source may be the Euphrosyne family of dark, asteroids on highly inclined (or tilted) orbits in the outer asteroid belt.

› The study used data from NASA's NEOWISE space telescope, which has a second life following its reactivation in 2013.

High above the plane of our solar system, near the asteroid-rich abyss between Mars and Jupiter, scientists have found a unique family of space rocks. These interplanetary oddballs are the Euphrosyne (pronounced you-FROH-seh-nee) asteroids, and by any measure they have been distant, dark and mysterious -- until now.

Distributed at the outer edge of the asteroid belt, the Euphrosynes have an unusual orbital path that juts well above the ecliptic, the equator of the solar system. The asteroid after which they are named, Euphrosyne -- for an ancient Greek goddess of mirth -- is about 156 miles (260 kilometers) across and is one of the 10 largest asteroids in the main belt. Current-day Euphrosyne is thought to be a remnant of a massive collision about 700 million years ago that formed the family of smaller asteroids bearing its name. Scientists think this event was one of the last great collisions in the solar system.

A new study conducted by scientists at NASA's Jet Propulsion Laboratory in Pasadena, California, used the agency's orbiting Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) telescope to look at these unusual asteroids to learn more about Near Earth Objects, or NEOs, and their potential threat to Earth.

NEOs are bodies whose orbits around the sun approach the orbit of Earth; this population is short-lived on astronomical timescales and is fed by other reservoirs of bodies in our solar system. As they orbit the sun, NEOs can occasionally have close approaches to Earth. For this reason alone -- the safety of our home planet -- the study of such objects is important.

As a result of their study, the JPL researchers believe the Euphrosynes may be the source of some of the dark NEOs found to be on long, highly inclined orbits. They found that, through gravitational interactions with Saturn, Euphrosyne asteroids can evolve into NEOs over timescales of millions of years.

NEOs can originate in either the asteroid belt or the more distant outer reaches of the solar system. Those from the asteroid belt are thought to evolve toward Earth's orbit through collisions and the gravitational influence of the planets. Originating well above the ecliptic and near the far edge of the asteroid belt, the forces that shape their trajectories toward Earth are far more moderate.

"The Euphrosynes have a gentle resonance with the orbit of Saturn that slowly moves these objects, eventually turning some of them into NEOs," said Joseph Masiero, JPL's lead scientist on the Euphrosynes study. "This particular gravitational resonance tends to push some of the larger fragments of the Euphrosyne family into near-Earth space."

By studying the Euphrosyne family asteroids with NEOWISE, JPL scientists have been able to measure their sizes and the amount of solar energy they reflect. Since NEOWISE operates in the infrared portion of the spectrum, it detects heat. Therefore, it can see dark objects far better than telescopes operating at visible wavelengths, which sense reflected sunlight. Its heat-sensing capability also allows it to measure sizes more accurately.

The 1,400 Euphrosyne asteroids studied by Masiero and his colleagues turned out to be large and dark, with highly inclined and elliptical orbits. These traits make them good candidates for the source of some of the dark NEOs the NEOWISE telescope detects and discovers, particularly those that also have highly inclined orbits.

NEOWISE was originally launched as an astrophysics mission in 2009 as the Wide-field Infrared Survey Explorer, or WISE. It operated until 2011 and was then shut down. But the spacecraft, now dubbed NEOWISE, would get a second life. "NEOWISE is a great tool for searching for near-Earth asteroids, particularly high-inclination, dark objects," Masiero said.

There are over 700,000 asteroidal bodies currently known in the main belt that range in size from large boulders to about 60 percent of the diameter of Earth's moon, with many yet to be discovered. This makes finding the specific point of origin of most NEOs extremely difficult.

With the Euphrosynes it's different. "Most near-Earth objects come from a number of sources in the inner region of the main belt, and they are quickly mixed around," Masiero said. "But with objects coming from this family, in such a unique region, we are able to draw a likely path for some of the unusual, dark NEOs we find back to the collision in which they were born."

A better understanding of the origins and behaviors of these mysterious objects will give researchers a clearer picture of asteroids in general, and in particular the NEOs that skirt our home planet's neighborhood. Such studies are important, and potentially critical, to the future of humanity, which is a primary reason JPL and its partners continue to relentlessly track these wanderers within our solar system. To date, U.S. assets have discovered more than 98 percent of the known NEOs.

NASA's Jet Propulsion Laboratory in Pasadena, California, manages the NEOWISE mission for NASA's Science Mission Directorate in Washington. The Space Dynamics Laboratory in Logan, Utah, built the science instrument. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built the spacecraft. Science operations and data processing take place at the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA.

NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Office for NASA's Science Mission Directorate in Washington.

For more information about NEOWISE, visit:

http://www.nasa.gov/neowise

More information about asteroids and near-Earth objects is available at:

http://neo.jpl.nasa.gov

http://www.jpl.nasa.gov/asteroidwatch

News Media Contact

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

818-393-9011

agle@jpl.nasa.gov

2015-256

Related News

Mars .

NASA’s Ingenuity Mars Helicopter Succeeds in Historic First Flight

Mars .

NASA to Attempt First Controlled Flight on Mars As Soon As Monday

Mars .

NASA’s Mars Helicopter to Make First Flight Attempt

Mars .

NASA’s Odyssey Orbiter Marks 20 Historic Years of Mapping Mars

Solar System .

Probing for Life in the Icy Crusts of Ocean Worlds

Mars .

NASA’s First Weather Report From Jezero Crater on Mars

Mars .

NASA Invites Public to Take Flight With Ingenuity Mars Helicopter

Mars .

NASA’s Mars Helicopter Survives First Cold Martian Night on Its Own

Mars .

Sensors Collect Crucial Data on Mars Landings With Arrival of Perseverance

Mars .

NASA’s InSight Detects Two Sizable Quakes on Mars

Explore More

Image .

Goldstone Radar Observations of Asteroid 2001 FO32

Video .

What's Up - April 2021

Image .

Europa Clipper Spacecraft (Illustration)

Image .

Europa Imaging System Wide Angle Camera

Image .

Faraday Cups Up Close: NASA's Europa Clipper

Image .

Europa Clipper's Thermal Tubing

Image .

Europa Imaging System Narrow Angle Camera

Image .

Europa Clipper REASON Testing on the Mesa

Image .

Europa Clipper's Europa Imaging System in the Works

Image .

Preparing NASA's Europa Clipper's Plasma Instrument

About JPL
Who We Are
Executive Council
Directors of JPL
JPL History
Documentary Series
Virtual Tour
Annual Reports
Missions
All
Current
Past
Future
News
All
Earth
Mars
Solar System
Universe
Technology
Galleries
Images
Videos
Audio
Podcasts
Infographics
Visions of the Future
Slice of History
Engage
JPL and the Community
Lecture Series
Public Tours
Events
Team Competitions
JPL Speakers Bureau
Topics
Solar System
Mars
Earth
Climate Change
Stars and Galaxies
Exoplanets
Technology
JPL Life
For Media
Contacts and Information
Press Kits
More
Asteroid Watch
Robotics at JPL
Subscribe to Newsletter
Universe Newsletter
Social Media
RSS
Get the Latest from JPL
Follow Us

JPL is a federally funded research and development center managed for NASA by Caltech.

More from JPL
Careers Education Science & Technology Acquisitions JPL Store
Careers
Education
Science & Technology
Acquisitions
JPL Store
Related NASA Sites
Basics of Spaceflight
Climate Kids
Earth / Global Climate Change
Exoplanet Exploration
Mars Exploration
Solar System Exploration
Space Place
NASA's Eyes Visualization Project
Voyager Interstellar Mission
NASA
Caltech
Privacy
Image Policy
FAQ
Feedback
Site Manager: Veronica McGregor
Site Editors: Tony Greicius, Randal Jackson, Naomi Hartono