Planetary Radar

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Planetary Radar studies the celestial bodies in our solar system: planets, moons, asteroids and comets. Directed by the 1000 foot reflector, a powerful beam of radio energy is transmitted in the direction of the target object. A very small portion of this energy is reflected by the target, back in the direction of earth. This weak radio echo is collected, focused and detected by the Arecibo Telescope. The signal is processed, then analyzed to yield information about the surface roughness, composition, size, shape, rotation and path of the target object. The Arecibo Radio Telescope has been used to measure the rotation rate of Mercury and to generate surface maps of large areas on Mercury, Venus and the Moon, locating mountain ranges, craters and rift valleys. The first detection of radar echo from a comet was made at Arecibo.

Science Group

The Planetary Radar Science group is a department of the Arecibo Observatory, which is an NSF facility operated under cooperative agreement by University of Central Florida (UCF), Yang Enterprises (YEI) and Universidad Metropolitana (UMET). The Arecibo Observatory Planetary Radar program is fully funded through grants to USRA from NASA's Near-Earth Object Observations program (Grants NNX12AF24G and NNX13AQ46G). The Planetary Radar Science group is also partnered with the Center for Lunar Science and Exploration node (USRA-Lunar and Planetary Institute/NASA-Johnson Space Center) of the NASA Solar System Exploration Research Virtual Institute program.

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S-Band Spotlight

Planetary Science

Arecibo Continues Operations through Pandemic to Observe Potentially Hazardous Asteroid 1998 OR2

The Arecibo Observatory is using its powerful radar system to track (52768) 1998 OR2, a near-Earth asteroid that will safely pass the Earth at a distance 16 times further than the distance to the Moon on April 29. The radar data confirm that 1998 OR2 is approximately 2 km in diameter and rotates once every 4.1 hours, as was suggested by optical observations. The range-Doppler images uniquely revealed the overall shape of the asteroid and some smaller-scale topographic features, such as hills and ridges. Read More

Planetary Science

Discovery Announcement of Binary System 2020 BX12

Radar images obtained by the Arecibo Observatory on the 4th and 5th of February revealed that near-Earth asteroid 2020 BX12 is a binary asteroid. The detection of a satellite was made during the first planetary radar observations conducted at the observatory following a month-long shutdown of telescope operations caused by a series of earthquakes striking the southern part of the island of Puerto Rico. The primary asteroid was discovered on the 27th of January by the ATLAS survey on Mauna Loa in Hawaii and fits the definition of a potentially hazardous asteroid (PHA) due to its size and minimum orbit intersection distance (MOID) of 302,000 km (188,000 miles) from the Earth. While this means it could conceivably come closer to the Earth than the Moon, 2020 BX12 poses no danger at this time and is currently receding from Earth. Read More

Planetary Science

Arecibo Observatory Radar Tracks Close Flyby of Asteroid 2019 OK

On July 24th 2019, an asteroid called 2019 OK passed by the Earth at only 1/5 the distance to the Moon, with a relative velocity of 15 miles per second (~55,000 miles per hour). 2019 OK was discovered by the SONEAR Observatory in Brazil just one day before it zipped past the Earth. It is estimated to be between 50 – 130 meters (165 – 430 ft) in size. Read More

Observatories Team Up to Reveal Rare Double Asteroid
Planetary Science

Observatories Team Up to Reveal Rare Double Asteroid

New observations by three of the world‘s largest radio telescopes have revealed that an asteroid discovered last year is actually two objects, each about 3,000 feet (900 meters) in size, orbiting each other. Near-Earth asteroid 2017 YE5 was discovered with observations provided by the Morocco Oukaimeden Sky Survey on Dec. 21, 2017, but no details about the asteroid's physical properties were known until the end of June. This is only the fourth "equal mass" binary near-Earth asteroid ever detected, consisting of two objects nearly identical in size, orbiting each other. The new observations provide the most detailed images ever obtained of this type of binary asteroid. Read More

Near-Earth asteroid (505657) 2014 SR339
Planetary Science

Arecibo observed the near-Earth asteroid (505657) 2014 SR339

Arecibo observed the near-Earth asteroid (505657) 2014 SR339 using its NASA-funded planetary radar system on February 9, 2018. Read More

Phaethon - Figure 1

Arecibo Planetary Radar Returns to Action with Images of Asteroid Phaethon

Columbia, MD and Puerto Rico: After several months of downtime in the aftermath of Hurricane Maria, the Arecibo Observatory Planetary Radar returned to normal operation providing the best images to date of near-Earth asteroid 3200 Phaethon, which is thought to be the parent body for the Geminids meteor shower. Radar images reveal Phaethon to be roughly spherical with a diameter of about 6 km (3.6 mi), roughly 1 km (0.6 mi) larger than previous estimates. Read More


Publications making use of Arecibo Observatory Data


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NOTE: Any opinions, findings, or recommendations expressed here do not necessarily reflect the views of the Arecibo Observatory, the National Science Foundation (NSF), University of Central Florida (UCF), Yang Enterprises (YEI), and Universidad Metropolitana (UMET), or the National Aeronautics and Space Administration (NASA). This website section is maintained by Dr. Sean Marshall