High Resolution Radar at Arecibo Observatory Reveals Asteroid As a Beauty,
Not a Beast
Arecibo and NASA Scientists using Earth-based radar have produced sharp views of a recently-discovered asteroid as it slid safely past our planet. Taken on June 8, 2014, the new views of asteroid designated 2014 HQ124--a beauty of an asteroid, not a beast--are some of the most detailed images of a near-Earth asteroid ever obtained with Arecibo Observatory and Goldstone Solar System Radar.
On Sunday, June 8, 2014, asteroid 2014 HQ124 safely passed Earth a little over three times the distance from Earth to the Moon (about 1.3 million kilometers or 800,000 miles). Arecibo Observatory together with with the Goldstone Solar System Radar observed HQ124 nine hours after closest approach.
Radar images of 2014 HQ124 show an elongated asteroid with an irregular surface at least 370 meters (1200 feet) in size, slightly larger than the 305-meter (1000 foot) Arecibo Observatory dish. These images were taken using Goldstone and Arecibo Observatory radar. The resolution in the vertical direction is 3.75 meters/pixel. Earth and the radar transmitter are toward the top of each frame. Individual images represent ten minutes of data.
A diagram showing the orbits of the Earth, Mars, and asteroid 2014 HQ124 near the time of closest approach on June 8, 2014. The asteroid passed by the Earth in the sunward direction, moving rapidly from south to north, and requiring midday observations at Arecibo Observatory as it passed through the upward facing beam of the 305 meter dish.
Most radar experiments involve one radio telescope transmitting signal to the asteroid, then receiving reflected radio waves from the asteroid. But for observing asteroid 2014 HQ124, scientists had the 70-meter (230-foot) Goldstone--also known as DSS-14--transmit to the asteroid, then the 305-meter (1000-foot) Arecibo Observatory collected the reflected waves. “We used two telescopes because that combination allowed us to get images with twice as much detail as Arecibo could achieve otherwise,” said Lance Benner, a scientist at the Jet Propulsion Laboratory who led the radar observations at Goldstone.
Using this configuration - Goldstone transmitting, Arecibo receiving - was made possible by newly-installed hardware at Arecibo that allows it to combine the 3.75-m resolution of the Goldstone radar transmitter with the unmatched sensitivity of the 305-m Arecibo telescope, providing the first high resolution radar images of an asteroid with this level of clarity from any radar system. Arecibo and Goldstone scientists hope to use this new system regularly for studying near-Earth asteroids.
Radar astronomers Michael Nolan and Ellen Howell lead the observations of HQ124 from Arecibo, along with other staff members and three summer students participating in the National Science Foundation’s Research Experience for Undergraduates program. In addition to Benner, Marina Brozović, Joseph Jao, and Clement Lee of the Jet Propulsion Laboratory/Caltech carried out radar observations from Goldstone.
In addition to receiving signal from Goldstone DSS-14, Arecibo Observatory transmitted and four Very Long Baseline Array telescopes in Texas, New Mexico, and Arizona collected the returned signal. “Using multiple telescopes to track the motion of an asteroid's radar echo across the Earth, we can determine its rotation independently of radar imaging,” said Michael Busch, a radio astronomer involved with the observations at the SETI Institute in Mountain View, California. “This resolves ambiguities in the radar images and is essential for long-term trajectory prediction.”
Radar images of 2014 HQ124 show an elongated asteroid with an irregular surface at least 370 meters (1200 feet) in size, slightly larger than the 305-meter (1000 foot) Arecibo Observatory dish. This asteroid spins on its axis in approximately 20 hours.
View Animation: Arecibo-Goldstone Observations of 2014 HQ124
Radar delay-Doppler images of asteroid 2014 HQ124. The Earth and radar transmitter are toward the top of each frame. Each frame has the same orientation, delay-Doppler dimensions, resolution (3.75 m by 0.0125 Hz), and duration (10 minutes). Arecibo images appear on the top row and Goldstone images appear on the other rows: Using Arecibo eliminated the “snow” visible in the other images. There is a gap of about 35 minutes between rows 1 and 2. Credit: Marina Brozović and Joseph Jao, Jet Propulsion Laboratory/Caltech/NASA/USRA/Arecibo Observatory/NSF.
"These radar observations show that the asteroid is a beauty, not a beast", said Alessondra Springmann, a data analyst at Arecibo Observatory, noting the complex structure of the asteroid and its peanut shape visible in the radar data.
Arecibo Observatory and Goldstone radar facilities are unique among telescopes on Earth for their ability to resolve features on asteroids, while most optical telescopes on the ground would see these cosmic neighbors simply as unresolved points of light.
Located in Puerto Rico, the Arecibo Observatory is home to the world’s largest and most sensitive single-dish radio telescope at 305 meters (1000 feet) across. This facility dedicates hundreds of hours a year of its telescope time to improving our knowledge of near-Earth asteroids and comets. The Arecibo Observatory is operated by SRI International under a cooperative agreement with the National Science Foundation, and in alliance with the Sistema Universitario Ana G. Méndez-Universidad Metropolitana and the Universities Space Research Association. The Arecibo Planetary Radar program is supported by NASA’s Near Earth Object Observation program.
For more images and information on asteroid 2014 HQ124, see the Arecibo Observatory’s planetary radar pages:
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