A Near-Earth Asteroid Census

Wise_wise2011-nea-a_500

WISE_WISE2011-NEA-a September 29th, 2011

Credit: NASA/JPL-Caltech

This chart shows how data from NASA's Wide-field Infrared Survey Explorer, or WISE, has led to revisions in the estimated population of near-Earth asteroids. The infrared-sensing telescope performed the most accurate survey to date of a slice of this population as part of project called NEOWISE. This allowed the science team to make new estimates of the total numbers of the objects in different size categories. NEOWISE observed more than 500 objects larger than 100-meters (330-feet) wide -- what can be thought of as medium to large-size asteroids. Near-Earth asteroids smaller than this size range were not studied, and near-Earth comets will be analyzed at a later time. Asteroid sizes are not drawn to scale in the chart.

Each asteroid image represents about 100 actual objects. Near-Earth asteroids that have already been found are filled in and appear brown. An entire row of asteroid images through the blue outlines shows how many total objects were thought to exist before the NEOWISE survey. The green outlines show the reduced new estimates based on the NEOWISE data.

As the graphic reveals, only a small difference was observed in the estimated total numbers of the largest asteroids -- the ones with the potential for global consequences should they impact Earth. For the medium-sized asteroids, which could still destroy a metropolitan area, new estimates predict fewer space rocks than previously thought. Details are listed below.

--For the largest asteroids, larger than 1,000 meters (3,300 feet), NEOWISE data revises the total population down to 981 from a prior estimate of about 1,000. While this is not a dramatic difference, the findings show that NASA has met an initial near-Earth asteroid goal agreed to with Congress in 1998, calling for at least 90 percent of the largest objects to be found. There are an estimated 911 objects of this size range known, which means that NASA has found 93 percent. That leaves roughly 70 of these bodies left to find.

--The NEOWISE data reveals an approximately 44 percent decline in the estimated numbers of medium-sized asteroids, which are defined as those objects between 100 meters and 1,000 meters (330 and 3,300 feet). Estimates now indicate about 19,500, where as 35,000 were thought to exist before.

--The study does not apply to objects smaller than 100 meters (330 feet), but it is estimated that there are more than a million in this size range based on previous studies.

Image credit: NASA/JPL-Caltech

Image Source: /image/WISE/WISE2011-NEA-a

Curator: Wide-field Infrared Survey Explorer, Berkeley, CA, USA

Image Use Policy: Pulic Domain

Image Details

Image Type
Chart
Object Name
Near-Earth Asteroid; NEA; NEO NEA NEO
Subject - Solar System
Interplanetary Body » Asteroid
Wise_wise2011-nea-a_1280
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ID
WISE2011-NEA-a
Subject Category
A.2.3  
Subject Name
Near-Earth Asteroid; NEA; NEO, NEA, NEO
Credits
NASA/JPL-Caltech
Lightyears
Redshift
Reference Url
/image/WISE/WISE2011-NEA-a
Type
Chart
Image Quality
Good
Distance Notes
Facility
Instrument
Color Assignment
Band
Bandpass
Central Wavelength
Start Time
Integration Time
Dataset ID
Notes
Coordinate Frame
Equinox
Reference Value
Reference Dimension
Reference Pixel
Scale
Rotation
Coordinate System Projection:
Quality
FITS Header
Notes
Creator (Curator)
Wide-field Infrared Survey Explorer
URL
http://wise.astro.ucla.edu
Name
Email
outreach@ssl.berkeley.edu
Telephone
Address
7 Gauss Way
City
Berkeley
State/Province
CA
Postal Code
94720
Country
USA
Rights
Pulic Domain
Publisher
Publisher ID
WISE
Resource ID
Resource URL
/image/WISE/WISE2011-NEA-a
Related Resources
Metadata Date
2012-10-10 18:56:23 -0700
Metadata Version
1.2
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Detailed color mapping information coming soon...

 

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There is no distance meta data in this image.