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NASA's Search for Asteroids to Help Protect Earth and Understand Our History
April 22, 2014

Reports about NASA’s routine detection and tracking of near-Earth objects (NEOs) may not be as exciting as Hollywood scenarios of asteroid impact disasters, but NEO detection and tracking is a 24/7 job the agency and its partners takes seriously. In fact, NASA places a high priority on finding hazardous asteroids and protecting our home planet from them.

NEOs are asteroids and comets with orbits that come within 28 million miles of Earth's path around the sun, and NASA has been studying them since the 1970s.  NASA's NEO Observations Program, at NASA Headquarters in Washington, is responsible for the Agency’s efforts at finding, tracking, and characterizing NEOs. The agency’s Jet Propulsion Laboratory (JPL) in Pasadena, California, hosts the NEO Program Office for Headquarters.

Planning for the possibility of a devastating asteroid impact with Earth and working to prevent such disasters is now officially on the national and international agenda.

A Constant Stream of Impacts

The Earth collides with small amounts of natural space debris constantly. Scientists estimate that our planet accumulates about 100 tons of material in the form of small grains of dust and sand from space every day. Impacts of larger meteoroids of a few meters in size also occur frequently. On an almost weekly basis, an object large enough to cause an energy release of up to tens of kilotons will impact Earth’s atmosphere. In this size range, a NEO impact causes no effects at the surface, other than a rare small meteorite striking a building or even a car.

NASA’s mission is to find those that are much larger – several tens of meters of size and larger – which could cause significant harm to populated areas on the Earth if they were to strike without warning. These impacts occur on time scales of decades to once a century, but could occur at any time. Because of the potential for harm to human populations, NASA is working to further improve its capability to watch out for these larger asteroids.

Planetary Defense

NASA, along with its partners in the U.S. and abroad, are working 24/7 to detect, track, and characterize NEOs, identify objects that pose a risk of Earth impact, and develop options for what is called “planetary defense”.

In 1994, Congress directed NASA to develop a plan to discover, characterize and catalog potentially hazardous NEOs larger than 1 kilometer in size. In 1998, NASA formally established a NEO program in response to the congressional directive to discover at least 90 percent of 1-kilometer-sized NEOs within 10 years. NASA fulfilled this mandate by 2010. 

In 2005, Congress again directed NASA to find at least 90 percent of potentially hazardous NEOs sized 140 meters or larger by the end of 2020. In addition, Congress directed NASA to analyze options for diverting NEOs posing a risk of Earth impact. Current national space policy directs NASA to pursue capabilities, in cooperation with other departments, agencies, and commercial partners, to detect, track, catalog, and characterize near-Earth objects to reduce the risk of harm to humans from an unexpected impact on our planet, and to identify potentially resource-rich planetary objects.

In February of this year, FEMA Administrator Craig Fugate and NASA Administrator Charlie Bolden reported to John Holdren, director of the White House Office of Science and Technology Policy (OSTP), on their plans to form a NEO Impact Working Group as “one aspect of better preparing the Nation to respond” to NEO impact hazards. The Working Group will review disaster response plans and recommend future exercises and messaging for NEO impact scenarios."

NASA and FEMA also provided OSTP with a report on their first joint NEO-impact tabletop exercise, conducted in 2013 to familiarize FEMA officials with the nature of NEO impacts and demonstrate how warnings of an impact might evolve if the approaching object was detected a short time before possible impact. NASA and FEMA will conduct a second exercise later this spring.

NASA’s NEO Observation Program is also a key member of the International Asteroid Warning Network (IAWN), organized last year at the recommendation of the United Nations Committee on the Peaceful Uses of Outer Space (UN COPUOS).  The IAWN operates independently of the U.N., under the auspices of interested national agencies and astronomical institutions. The IAWN steering committee held its first meeting in January at the International Astronomical Union’s (IAU’s) Minor Planet Center located at the Harvard Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.

A central NEO database for the global NEO observer community resides at the Minor Planet Center (MPC) in Cambridge, Mass. Data from the MPC feeds into NASA’s asteroid monitoring system called  “Sentry,” which is operated by JPL.  Sentry automatically retrieves new observations from the MPC database, updates orbits of NEOs, then computes a new impact hazard assessment. It is an invaluable system to bring attention or remove risks of a potential impact. This globally distributed NEO impact hazard monitoring system works efficiently, 24/7. NASA's NEO Observation Program supports this process at every stage, from individual observers to observing facilities and to the MPC and Sentry.

Also in response to UN COPUOS recommendations, space agencies are establishing a Space Missions Planning Advisory Group (SMPAG) to consider options for planetary defense against potential NEO impacts with Earth. SMPAG held a formative meeting this February at the European Space Agency’s Operations Center in Darmstadt, Germany.  A second meeting will be held in June in Vienna, Austria.

[image-36]Can science and technology protect Earth from future impacts?

NASA and its partners are working on this goal. In fiscal year 2013, the NEO Observation Program supported 41 ongoing projects (compared to 29 in fiscal year 2012), including 5 detection and tracking campaigns, 10 follow-up surveys, 9 characterization efforts, 3 radar projects, 4 data processing and management projects, 6 technology development projects, and 4 studies of techniques for impact mitigation. Ten of these projects are being conducted by NASA centers, 2 by other federal agencies, 4 by space science institutes, 20 by university researchers, and 3 by private citizens.

While the space science community was already well aware of the potential hazard of asteroid impacts with Earth, the February 2013 atmospheric impact of a 20-meter-sized asteroid over Chelyabinsk, Russia, greatly raised public awareness about the risk. More importantly, the Chelyabinsk asteroid incident provided a wealth of data on NEO impacts with Earth. Scientists for the first time were able to assemble a detailed explanation of the effects in Earth’s atmosphere from a small asteroid impact. The unprecedented data obtained about this impact event has revolutionized scientists' understanding of this natural phenomenon.

NASA’s NEO Program Today

From 1998 to 2011, the NEO Observation Program operated on a budget of a few million dollars a year. Starting in 2012, President Obama’s fiscal year budget request included, and Congress appropriated, $20.5 million to expand the program. It was further increased to $40M starting with the 2014 NASA budget.

In addition to supporting an expanded NEO program, NASA has twice re-purposed its Wide Field Infrared Explorer (WISE) spacecraft to find, track, and characterize NEOs. WISE began observations in 2010 and completed its primary astronomical mission in 2011. As part of a concurrent project called the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE), the spacecraft also made the most accurate survey to date of the size distribution of NEOs.

Following 31 months in hibernation, NASA has now reactivated NEOWISE to further assist efforts to identify and characterize potentially hazardous NEOs. NEOWISE also can assist in characterizing previously detected asteroids that could be considered potential destinations for future exploration missions.

"The data collected by NEOWISE have proven to be a gold mine for the discovery and characterization of the NEO population," said Lindley Johnson, NASA's NEO Observation Program Executive at NASA Headquarters.

A Visit to a Larger Asteroid

Asteroid impacts are an element of Earth’s natural history. Scientists are interested in studying asteroids and comets to learn more about the origins of our solar system, the source of water on Earth, and even the origin of organic molecules that led to the development of life.

In 2016, NASA will launch its Origins-Spectral Interpretation Resource Identification Security Regolith Explorer (OSIRIS-REx) spacecraft. The robotic mission will spend more than two years at Bennu, a 1,760-foot (500-meter)-diameter asteroid. The spacecraft will collect a sample of Bennu's surface and return it to Earth.

The mission’s goal is to address basic questions about the composition of the very early solar system, the source of organic materials and water that made life possible on Earth, and to better predict the orbits of asteroids that represent collision threats to the Earth.

The Path Forward

Building on the foundation laid down by NASA’s NEO Observations Program, in 2013, NASA announced its Asteroid Initiative. This includes a bold mission to identify, capture and relocate an asteroid through the Asteroid Redirect Mission, and an Asteroid Grand Challenge to find all asteroids threats to the human population and know what to do about them.

In March 2014, NASA launched the Asteroid Data Hunter contest in partnership with Planetary Resources to create better algorithms to hunt for undiscovered asteroids in existing data. NASA is also working on partnerships with the technology-based, do-it-yourself Maker community and on future crowdsourcing activities to find and track asteroids, and foster a global solution to dealing with asteroid threats.

The expanding NEO Observations Program, the OSIRIS REx mission and the commitment to seeking new and innovative solutions to this global issue will also help to inform NASA's science, technology and human exploration efforts to achieve President Obama's goal of sending humans to an asteroid by 2025 and then on to Mars in the 2030’s.

For more information about NASA’s Near Earth Object Observation Program, visit:


For NEO news on close approaches to Earth, visit:


For more information about NASA’s Asteroid Initiative, visit:



This artist's concept shows the Wide-field Infrared Survey Explorer, or WISE spacecraft, in its orbit around Earth. In 2013, the mission was brought out of hibernation to hunt for more asteroids and comets in a project called NEOWISE.
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Page Last Updated: April 22nd, 2014
Page Editor: Sarah Loff