Asteroid Program

Small Asteroid Is Earth’s Constant Companion

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Asteroid 2016 HO3 has an orbit around the sun that keeps it as a constant companion of Earth. Credit: NASA/JPL-Caltech

A small asteroid has been discovered in an orbit around the sun that keeps it as a constant companion of Earth, and it will remain so for centuries to come.

As it orbits the sun, this new asteroid, designated 2016 HO3, appears to circle around Earth as well. It is too distant to be considered a true satellite of our planet, but it is the best and most stable example to date of a near-Earth companion, or “quasi-satellite.”

“Since 2016 HO3 loops around our planet, but never ventures very far away as we both go around the sun, we refer to it as a quasi-satellite of Earth,” said Paul Chodas, manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California. 

“One other asteroid — 2003 YN107 — followed a similar orbital pattern for a while over 10 years ago, but it has since departed our vicinity. This new asteroid is much more locked onto us. Our calculations indicate 2016 HO3 has been a stable quasi-satellite of Earth for almost a century, and it will continue to follow this pattern as Earth’s companion for centuries to come.”


This video shows the obit of the Earth and asteroid 2016 H03 (If video does not appear, click on Asteroid Orbit).

In its yearly trek around the sun, asteroid 2016 HO3 spends about half of the time closer to the sun than Earth and passes ahead of our planet, and about half of the time farther away, causing it to fall behind. Its orbit is also tilted a little, causing it to bob up and then down once each year through Earth’s orbital plane. In effect, this small asteroid is caught in a game of leap frog with Earth that will last for hundreds of years.

The asteroid’s orbit also undergoes a slow, back-and-forth twist over multiple decades. “The asteroid’s loops around Earth drift a little ahead or behind from year to year, but when they drift too far forward or backward, Earth’s gravity is just strong enough to reverse the drift and hold onto the asteroid so that it never wanders farther away than about 100 times the distance of the moon,” said Chodas. “The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon. In effect, this small asteroid is caught in a little dance with Earth.”

Asteroizd s2016 HO3 was first spotted on April 27, 2016, by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii, operated by the University of Hawaii’s Institute for Astronomy and funded by NASA’s Planetary Defense Coordination Office. The size of this object has not yet been firmly established, but it is likely larger than 120 feet (40 meters) and smaller than 300 feet (100 meters).

The Center for NEO Studies website has a complete list of recent and upcoming close approaches, as well as all other data on the orbits of known NEOs, so scientists and members of the media and public can track information on known objects.

For asteroid news and updates, follow AsteroidWatch on Twitter:

Halloween Skies to Include Dead Comet Flyby

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The large space rock that will zip past Earth this Halloween is most likely a dead comet that, fittingly, bears an eerie resemblance to a skull.

Scientists observing asteroid 2015 TB145 with NASA’s Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii, have determined that the celestial object is more than likely a dead comet that has shed its volatiles after numerous passes around the sun.

The belated comet has also been observed by optical and radar observatories around the world, providing even more data, including our first close-up views of its surface. Asteroid 2015 TB145 will safely fly by our planet at just under 1.3 lunar distances, or about 302,000 miles (486,000 kilometers), on Halloween (Oct. 31) at 1 p.m. EDT (10 a.m. PDT, 17:00 UTC).

The first radar images of the dead comet were generated by the National Science Foundation’s 305-meter (1,000-foot) Arecibo Observatory in Puerto Rico. The radar images from Arecibo indicate the object is spherical in shape and approximately 2,000 feet (600 meters) in diameter and completes a rotation about once every five hours. 

“The IRTF data may indicate that the object might be a dead comet, but in the Arecibo images it appears to have donned a skull costume for its Halloween flyby,” said Kelly Fast, IRTF program scientist at NASA Headquarters and acting program manager for NASA’s NEO Observations Program.

These first radar images from the National Science Foundation’s 1,000-foot (305-meter) Arecibo Observatory in Puerto Rico, indicate the near-Earth object is spherical in shape and approximately 2,000 feet (600 meters) in diameter. The radar images were taken on Oct. 30, 2015, and the image resolution is 25 feet (7.5 meters) per pixel.Image credit: NAIC-Arecibo/NSF

Managed by the University of Hawaii for NASA, the IRTF’s 3-meter (10 foot) telescope collected infrared data on the object. The data may finally put to rest the debate over whether 2015 TB145, with its unusual orbit, is an asteroid or is of cometary origin.

“We found that the object reflects about six percent of the light it receives from the sun,” said Vishnu Reddy, a research scientist at the Planetary Science Institute, Tucson, Arizona. “That is similar to fresh asphalt, and while here on Earth we think that is pretty dark, it is brighter than a typical comet which reflects only 3 to 5 percent of the light. That suggests it could be cometary in origin — but as there is no coma evident, the conclusion is it is a dead comet.”

Radar images generated by the Arecibo team are available at:

Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University of Hawaii’s Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object Observations (NEOO) Program. The next time the asteroid will be in Earth’s neighborhood will be in September 2018, when it will make a distant pass at about 24 million miles (38 million kilometers), or about a quarter the distance between Earth and the sun.

Radar is a powerful technique for studying an asteroid’s size, shape, rotation, surface features and surface roughness, and for improving the calculation of asteroid orbits. Radar measurements of asteroid distances and velocities often enable computation of asteroid orbits much further into the future than would be possible otherwise.

NASA places a high priority on tracking asteroids and protecting our home planet from them. In fact, the U.S. has the most robust and productive survey and detection program for discovering near-Earth objects (NEOs). To date, U.S.-funded assets have discovered over 98 percent of the known NEOs.

In addition to the resources NASA puts into understanding asteroids, it also partners with other U.S. government agencies, university-based astronomers, and space science institutes across the country, often with grants, interagency transfers and other contracts from NASA, and also with international space agencies and institutions that are working to track and better understand these objects. In addition, NASA values the work of numerous highly skilled amateur astronomers, whose accurate observational data helps improve asteroid orbits after they are found.

NASA’s Jet Propulsion Laboratory, Pasadena, California, hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program within the agency’s Science Mission Directorate.

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



NASA Spots the ‘Great Pumpkin’: Halloween Asteroid a Treat for Radar Astronomers

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This is a graphic depicting the orbit of asteroid 2015 TB145. The asteroid will safely fly past Earth slightly farther out than the moon’s orbit on Oct. 31 at 10:05 a.m. Pacific (1:05 p.m. EDT and 17:05 UTC). Image credit: NASA/JPL-Caltech

NASA scientists are tracking the upcoming Halloween flyby of asteroid 2015 TB145 with several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, California. The asteroid will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 10:01 a.m. PDT (1:01 p.m. EDT). Scientists are treating the flyby of the estimated 1,300-foot-wide (400-meter) asteroid as a science target of opportunity, allowing instruments on “spacecraft Earth” to scan it during the close pass.

Published on Oct 29, 2015JPL scientist Marina Brozovic explains how radar will be used to study asteroid 2015 TB145 when it safely passes Earth on Oct. 31, 2015. Scientists are tracking the Halloween flyby with several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, California. Radar images should be available within a few days of the flyby. The asteroid will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 10:01 a.m. PDT (1:01 p.m. EDT). Scientists are treating the flyby of the estimated 1,300-foot-wide (400-meter) asteroid as a science target of opportunity. 

Asteroid 2015 TB145 was discovered on Oct. 10, 2015, by the University of Hawaii’s Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui, part of the NASA-funded Near-Earth Object Observation (NEOO) Program. According to the catalog of near-Earth objects (NEOs) kept by the Minor Planet Center, this is the closest currently known approach by an object this large until asteroid 1999 AN10, at about 2,600 feet (800 meters) in size, approaches at about 1 lunar distance (238,000 miles from Earth) in August 2027.

“The trajectory of 2015 TB145 is well understood,” said Paul Chodas, manager of the Center for Near Earth Object Studies at NASA’s Jet Propulsion Laboratory, Pasadena, California. “At the point of closest approach, it will be no closer than about 300,000 miles — 480,000 kilometers or 1.3 lunar distances. Even though that is relatively close by celestial standards, it is expected to be fairly faint, so night-sky Earth observers would need at least a small telescope to view it.

The gravitational influence of the asteroid is so small it will have no detectable effect on the moon or anything here on Earth, including our planet’s tides or tectonic plates

The Center for NEO Studies at JPL is a central node for NEO data analysis in NASA’s Near-Earth Object Observation Program and a key group involved with the international collaboration of astronomers and scientists who keep watch on the sky with their telescopes, looking for asteroids that could be a hazard to impact our planet and predicting their paths through space for the foreseeable future

“The close approach of 2015 TB145 at about 1.3 times the distance of the moon’s orbit, coupled with its size, suggests it will be one of the best asteroids for radar imaging we’ll see for several years,” said Lance Benner, of JPL, who leads NASA’s asteroid radar research program. “We plan to test a new capability to obtain radar images with two-meter resolution for the first time and hope to see unprecedented levels of detail.”

During tracking, scientists will use the 34-meter (110-foot) DSS 13 antenna at Goldstone to bounce radio waves off the asteroid. Radar echoes will in turn be collected by the National Radio Astronomy Observatory’s Green Bank Telescope in Green Bank, West Virginia, and the National Astronomy and Ionosphere Center’s Arecibo Observatory, Puerto Rico. NASA scientists hope to obtain radar images of the asteroid as fine as about 7 feet (2 meters) per pixel. This should reveal a wealth of detail about the object’s surface features, shape, dimensions and other physical properties

“The asteroid’s orbit is very oblong with a high inclination to below the plane of the solar system,” said Benner. “Such a unique orbit, along with its high encounter velocity — about 35 kilometers or 22 miles per second — raises the question of whether it may be some type of comet. If so, then this would be the first time that the Goldstone radar has imaged a comet from such a close distance.”

NASA’s Near-Earth Object Observations Program detects, tracks and characterizes asteroids and comets passing within 30 million miles of Earth using both ground- and space-based telescopes. The NEOO Program, sometimes called “Spaceguard,” discovers these objects, characterizes the physical nature of a subset of them, and predicts their paths to determine if any could be potentially hazardous to our planet. There are no known credible impact threats to date — only the ongoing and harmless in-fall of meteoroids, tiny asteroids that burn up in the atmosphere

JPL hosts the Center for Near-Earth Object Studies for NASA’s Near-Earth Object Observations Program within the agency’s Science Mission Directorate. JPL is a division of the California Institute of Technology in Pasadena.

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

NASA Releases Tool Enabling Citizen Scientists to Examine Asteroid Vesta

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Vesta Trek’s interface allows explorers to fly around and even skim the surface of Vesta. Image credit: NASA

NASA has announced the release of Vesta Trek, a free, web-based application that provides detailed visualizations of Vesta, one of the largest asteroids in our solar system. 

NASA’s Dawn spacecraft studied Vesta from July 2011 to September 2012. Data gathered from multiple instruments aboard Dawn have been compiled into Vesta Trek’s user-friendly set of tools, enabling citizen scientists and students to study the asteroid’s features. The application includes:

— Interactive maps, including the ability to overlay a growing range of data sets including topography, mineralogy, abundance of elements and geology, as well as analysis tools for measuring the diameters, heights and depths of surface features and more

— 3-D printer-exportable topography so users can print physical models of Vesta’s surface 

— Standard keyboard gaming controls to maneuver a first-person visualization of “flying” across the surface of the asteroid

Vesta Trek was developed by NASA’s Lunar Mapping and Modeling Project (LMMP), which provides mission planners, lunar scientists and the public with analysis and data visualization tools for our moon, spanning multiple instruments on multiple missions. Vesta Trek represents the first application of LMMP’s capabilities to another world beyond the moon. LMMP-based portals for other worlds in our Solar System are currently in development.

“There’s nothing like seeing something with your own eyes, but these types of detailed data-visualizations are the next best thing,” said Kristen Erickson, Director, Science Engagement and Partnerships at NASA Headquarters in Washington. “We’re thrilled to release Vesta Trek to the citizen science community and the public, not only as a scientific tool, but as a portal to an immersive experience that, just by the nature of it, will allow a deeper understanding of Vesta and asteroids in general.”

NASA’s Dawn spacecraft is continuing its exploration in the asteroid belt, after arriving at the dwarf planet Ceres on March 6. As Dawn conducts its mapping and measurements of Ceres, LMMP will continue to work closely with the Dawn mission.

The Lunar Mapping and Modeling Project is managed by NASA’s Solar System Exploration Research Virtual Institute, headquartered at NASA’s Ames Research Center in Moffett Field, California. LMMP’s development team is based at NASA’s Jet Propulsion Laboratory in Pasadena, California. JPL also manages the Dawn mission for NASA. LMMP is funded by and receives direction from the Planetary Science Division of NASA’s Science Mission Directorate and the Advanced Exploration Systems program in NASA’s Human Exploration and Operations Mission Directorate, at NASA Headquarters in Washington.

To explore Vesta Trek, visit:

For more information about the Dawn mission, visit:

To learn more about the Solar System Exploration Research Virtual Institute, visit:

New Desktop Application Has Potential to Increase Asteroid Detection, Now Available to Public

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NASA’s Asteroid Data Hunter contest series was part of NASA’s Asteroid Grand Challenge, which is focused on finding all asteroid threats to human populations and knowing what to do about them. (Image Credit: NASA)

PRESS RELEASE (NASA) – A software application based on an algorithm created by a NASA challenge has the potential to increase the number of new asteroid discoveries by amateur astronomers.

Analysis of images taken of our solar system’s main belt asteroids between Mars and Jupiter using the algorithm showed a 15 percent increase in positive identification of new asteroids.

During a panel Sunday at the South by Southwest Festival in Austin, Texas, NASA representatives discussed how citizen scientists have made a difference in asteroid hunting. They also announced the release of a desktop software application developed by NASA in partnership with Planetary Resources, Inc., of Redmond, Washington. The application is based on an Asteroid Data Hunter-derived algorithm that analyzes images for potential asteroids. It’s a tool that can be used by amateur astronomers and citizen scientists.

The Asteroid Data Hunter challenge was part of NASA’s Asteroid Grand Challenge. The data hunter contest series, which was conducted in partnership with Planetary Resources under a Space Act Agreement, was announced at the 2014 South by Southwest Festival and concluded in December. The series offered a total of $55,000 in awards for participants to develop significantly improved algorithms to identify asteroids in images captured by ground-based telescopes. The winning solutions of each piece of the contest combined to create an application using the best algorithm that increased the detection sensitivity, minimized the number of false positives, ignored imperfections in the data, and ran effectively on all computer systems.

“The Asteroid Grand Challenge is seeking non-traditional partnerships to bring the citizen science and space enthusiast community into NASA’s work,” said Jason Kessler, program executive for NASA’s Asteroid Grand Challenge. “The Asteroid Data Hunter challenge has been successful beyond our hopes, creating something that makes a tangible difference to asteroid hunting astronomers and highlights the possibility for more people to play a role in protecting our planet.”

Catalina Sky Survey telescope

The Big Dipper rising behind the Catalina Sky Survey 60″ telescope. 

Image Credit: Catalina Sky Survey, University of Arizona

The data hunter challenge incorporated data provided by the Minor Planet Center (MPC), at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and images provided by the Catalina Sky Survey, an astronomical survey project run by the University of Arizona, Tucson, and focused on the discovery and study of near-Earth asteroids and comets.

“We applaud all the participants in the Asteroid Data Hunter challenge. We are extremely encouraged by the algorithm created and it’s already making a difference. This increase in knowledge will help assess more quickly which asteroids are potential threats, human destinations or resource rich,” said Chris Lewicki, president and chief engineer at Planetary Resources. “It has been exciting for our team to work with NASA on this project, and we also look forward to future space-based systems leveraging these results.”

Astronomers find asteroids by taking images of the same place in the sky and looking for star-like objects that move between frames, an approach that has been used since before Pluto was discovered in 1930. With more telescopes scanning the sky, the ever-increasing volume of data makes it impossible for astronomers to verify each detection by hand. This new algorithm gives astronomers the ability to use computers to autonomously and rapidly check the images and determine which objects are suitable for follow up, which leads to finding more asteroids than previously possible.

“The beauty of such archives is that the data doesn’t grow stale, and with novel approaches, techniques and algorithms, they can be harvested for new information. The participants of the Asteroid Data Hunter challenge did just that, probing observations of the night sky for new asteroids that might have slipped through the software cracks the first time the images were analyzed,” said Jose Luis Galache of the MPC. “Moreover, this software can now be used to analyze new images and is available to any observer who wants to use it. The Minor Planet Center applauds these efforts to provide superior tools to all, and looks forward to receiving new asteroid observations generated with them.”

The desktop software application is free and can be used on any basic desktop or laptop computer. Amateur astronomers may take images from their telescopes and analyze them with the application. The application will tell the user whether a matching asteroid record exists and offer a way to report new findings to the Minor Planet Center, which then confirms and archives new discoveries.

Through NASA’s asteroid initiative, the agency seeks to enhance its ongoing work in the identification and characterization of near-Earth objects for further scientific investigation. This work includes locating potentially hazardous asteroids and identifying those viable for redirection to a stable lunar orbit for future exploration by astronauts using NASA’s Space Launch System rocket and Orion spacecraft. The Asteroid Grand Challenge, one part of the asteroid initiative, expands the agency’s efforts beyond traditional boundaries and encourages partnerships and collaboration with a variety of organizations.

The algorithm contests were managed and executed by NASA’s Center of Excellence for Collaborative Innovation (CoECI). CoECI was established at the request of the White House Office of Science and Technology Policy to advance NASA’s open innovation efforts and extend that expertise to other federal agencies. CoECI uses the NASA Tournament Lab (NTL) for its advanced algorithmic and software development contests. Through its contract with the Crowd Innovation Lab at Harvard University, NTL uses Appirio’s Crowdsourcing platform powered by Topcoder to enable a community of more than 750,000 designers, developers and data scientists to create the most innovative, efficient and optimized solutions for specific, real-world challenges faced by NASA. Data storage of the Catalina Sky Survey data was provided by Amazon Web Services.

The new asteroid hunting application can be downloaded at:

For information about NASA’s Asteroid Grand Challenge, visit: