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

Radar Love: Asteroid Detection and Science

Dec 19, 2006
Radar observation of 1999 JM8 taken on August 3, 1999 with the Arecibo radar. The image reveals an asymmetric, irregularly-shaped object.
Radar images of asteroid 1950 DA obtained at Arecibo on Mar. 4, 2001, from a distance of 0.052 AU (22 lunar distances, eight million kilometers, five million miles). Radar echoes revealed a slightly asymmetrical spheroid with a mean diameter of 1.1 km. + See video

They are the celestial equivalent of sonograms. But their hazy outlines and ghostly features do not document the in-vivo development of a future taxpayer.

They are the celestial equivalent of sonograms. But their hazy outlines and ghostly features do not document the in-vivo development of a future taxpayer. Instead, they chronicle the exo-planetary comings-and-goings of some of Earth's least known, most nomadic, and at times most impactful neighbors.

They are radar echoes that are bounced off of asteroids. Scientists from NASA's Jet Propulsion Laboratory and around the world rely on their ethereal images to tell some out-of-this-world tales of near-Earth objects.

"The standard ground-based tools for asteroid science require a night's sky, and what you come away with in the end is an image of a dot," said JPL radar astronomer Dr. Steve Ostro. "With radar astronomy, the sky at high noon is just as inviting as that at midnight, and without launching a full-blown space mission we can actually get valuable information about the physical makeup of these objects."

In some respects, radar astronomy utilizes the same technology as your microwave oven. But do not bother to haul your glorified croissant warmer outside -- it will just confuse the neighbors. Radar astronomy employs the world's most massive dish-shaped antennas, which beam directed microwave signals at their targets, which can be as close as our moon and as far away as the moons of Saturn. These pulses bounce off the target, and the resulting "echo" is collected and precisely collated. The results can be astounding.

"The closer the target, the better the echo," said Ostro. "From them we can generate detailed three-dimensional models of the object, define its rotation precisely and get a good idea of its internal density distribution. You can even make out surface features. A good echo can give us a spatial resolution finer than 10 meters."

Radar astronomy has detected echoes from over 190 near-Earth asteroids to date and has found that, like snowflakes, no two are the same. The returning echoes have revealed both stony and metallic objects, some flying through the cold, dark reaches of space alone, while others have their own satellites. The data indicate that some asteroids have a very smooth surface, while others have very coarse terrain. And finally, their shapes are virtually anything that can be imagined.

One thing that does not have to be imagined is radar astronomy's ability to nail down the location of an object in time and space. This invaluable capability came in handy in the winter of 2004 when JPL's Near-Earth Object office was looking for a potentially hazardous asteroid called Apophis.

Discovered by astronomers using optical telescopes, Apophis quickly drew the interest of the near-Earth object monitoring community when its initial orbital plots indicated there was a possibility the 1,300-foot-wide chunk of space rock could impact Earth in 2029. The Near-Earth Object office knew what was needed was more detailed information about Apophis' location, which they could then use to plot out a more accurate orbit.

Under the watchful eye of Ostro and three other radar astronomers, microwaves from the Arecibo Observatory in Puerto Rico reached out and touched asteroid Apophis on Jan. 27, 29, and 30, 2005. The Arecibo data significantly improved the asteroid's orbital estimate, redefined its Earth approach distance in 2029 and decidedly reduced the probability of an Earth encounter during its next close approach in 2036.

The 1,000-foot diameter Arecibo telescope is one of only two places in the world where radar astronomy is effectively performed. The other is at the 70-meter Goldstone antenna in California's Mojave Desert. The two instruments are complementary. The Arecibo radar is not fully steerable (while Goldstone is), but it is 30 times more sensitive. Together they make a formidable asteroid reconnaissance team.

The future of radar astronomy may be just as amazing as some of the images and shape models of nearby space objects that its practitioners have already obtained. There is new technology in the pipeline that will allow imaging of surface features with up to four times more detail than what exists today. And then there are proposals on the table for a potential space mission to a near-Earth asteroid. Candidate asteroids for said mission will need to be pre-approved via detail scientific analysis. The kind of scientific analysis you can only get with radar astronomy.

News Media Contact

DC Agle

Jet Propulsion Laboratory, Pasadena, Calif.

818-393-9011

agle@jpl.nasa.gov

2006-00a

Related News

Solar System .

NASA’s Deep Space Network Welcomes a New Dish to the Family

Mars .

6 Things to Know About NASA’s Mars Helicopter on Its Way to Mars

Mars .

NASA to Host Virtual Briefing on February Perseverance Mars Rover Landing

Mars .

NASA InSight’s ‘Mole’ Ends Its Journey on Mars

Mars .

Mars 2020 Perseverance Rover to Capture Sounds From the Red Planet

Solar System .

NASA’s Juno Mission Expands Into the Future

Mars .

NASA’s Curiosity Rover Reaches Its 3,000th Day on Mars

Mars .

NASA Extends Exploration for Two Planetary Science Missions

Mars .

Celebrate the Perseverance Rover Landing With NASA's Student Challenge

Mars .

7 Things to Know About the NASA Rover About to Land on Mars

Explore More

Image .

Juno's Mission Goes On

Topic .

Solar System

Image .

A Hot Spot on Jupiter

Image .

Jupiter's Storm Oval BA As Viewed By An Artist

Image .

Two Views of Jupiter Hot Spot

Image .

A Jupiter Circumpolar Cyclone

Image .

Jupiter North Pole Detail

Video .

What's Up - January 2021

Image .

All Eight Northern Circumpolar Cyclones in 2020

Image .

Tracking Clouds on Jupiter

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
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
Social Media
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