Speaker
Description
The Goldstone Solar System Radar on NASA’s 70 meter DSS-14 antenna is the world's most sensitive planetary radar. DSS-14 is equipped with a high-power (~450 kW) radar used for observations of near-Earth asteroids (NEAs), comets, and other solar system targets. Goldstone transmits at a frequency of 8560 MHz (3.5 cm), is fully steerable, routinely tracks down to a declination of -35 degrees, and can cover nearly 80% of the sky. Goldstone has real-time processing that displays delay-Doppler data within seconds of its acquisition. Radar observations provide substantial reduction in orbital uncertainties; for newly-discovered objects, Goldstone astrometry routinely reduces distance uncertainties by several orders of magnitude.
As of December 2024, 1124 NEAs (~3% of the NEA population) have been observed by radar, and of these, 509 have been observed at Goldstone. 196 NEAs have been detected at Goldstone since the end of operations at Arecibo in 2020. Of these, 151 (77%) were detected for the first time; 112 are "Potentially Hazardous Asteroids;" 131 have absolute magnitudes < 22, corresponding to diameters larger than ~140 meters; and 63 were targets-of-opportunity observed shortly after discovery.
52 NEAs have been detected at Goldstone in 2024, setting a new annual record. This represents a factor of ~1.5 increase relative to the average from 2012-2018 and a ~five-fold increase relative to 15 years ago. Detailed delay-Doppler imaging at a resolution of 4 meters/pixel is now occurring >10 times annually.
During 2021-2024, we observed 18 binary systems, 13 of which were Goldstone discoveries, and two triples. 75 binary and triple systems have been observed by radar, of which ~70% were discovered by radar. Since 2020, 13 contact binaries have been discovered at Goldstone. ALL near-Earth contact binaries have been discovered using radar.
42% (N = 471) of all NEAs observed by radar were also observed by the NEOWISE spacecraft, including dozens detected at Goldstone since 2020. These observations provide calibration of diameters estimated from NEOWISE observations and will help calibrate diameters from the upcoming NEO Surveyor mission.
Radar observations at Goldstone have become much more flexible: Priority for radar observations is now comparable to that for spacecraft missions and considerably more time has been scheduled. Transmit authorization is no longer required, allowing much greater flexibility for short-notice targets-of-opportunity utilizing time already scheduled. Some NEAs are observed within one day of when discovery is announced. The klystron amplifiers are dramatically more reliable. In 2024, new equipment was installed that allows Goldstone to conduct monostatic observations for objects as close as one lunar distance.
This talk will discuss observational trends, detailed images from recent observing campaigns, and discuss plans for the next five years.
Acknowledgments: Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). This material is based in part upon work supported by NASA under the Science Mission Directorate Research and Analysis Programs.