12D-2 - Legacy of the Arecibo Radar Telescope

Abstract: Legacy: The Arecibo radar and radio telescope was inaugurated in 1963. With its 305-meter dish, it has a rich history of important atmospheric, planetary, and astronomical observations. It was conceived at the dawn of the space age as a radar probe of the low-earth-orbit region of the ionosphere, using a new technique known as incoherent scatter. It initially had a single transmitter and receiver frequency of 430 MHz, but rapidly expanded to multiple transmission frequencies for both atmospheric and planetary radar and wide-bandwidth passive measurements for radio astronomy. Among its accomplishments were the first observations of the surface of Venus, and accurate measurement of the distance to Venus, which led to an accurate knowledge of the value of the astronomical unit (AU). Another discovery made was of Langmuir turbulence in the ionosphere, the first confirmation of Einstein’s prediction of gravitational radiation, and the discovery of the first exoplanets.
The Arecibo 2.38-GHz radar system offered unique contribution to investigations of the physical and dynamical properties of near-Earth objects (NEOs). Every year approximately 100 NEOs were observed, including potentially hazardous asteroids, which were a priority of the NEO planetary radar observation program at Arecibo.
Status: One year after the collapse of the 900-ton Arecibo instrument platform on December 1, 2020, the Congressional representative for Puerto Rico, González-Colón, introduced a bipartisan House Resolution that highlighted contributions made by this instrument during nearly six decades in operation. The iconic telescope played a critical role within the scientific community and in the advancement of STEM education.
One of the functions of the Arecibo Science Advocacy Partnership (ASAP) is to increase public awareness of this rich legacy and to advocate for a renewal of the observatory’s capabilities through its replacement by a telescope of similar or greater capabilities.