Planetary Radar at the Arecibo Observatory

TL;DR

The paper discusses the 1990s upgrade of the Arecibo Observatory's planetary radar, which significantly enhanced its observational capabilities until its collapse in 2020, enabling detailed studies of planets, moons, rings, and near-Earth objects.

Contribution

It reports on the substantial sensitivity increase of the Arecibo radar system and its impact on planetary science and near-Earth object observations.

Findings

Radar observations of 889 near-Earth objects from 1997 to 2020.

Heterogeneous population of near-Earth asteroids indicating diverse origins.

Unique ability to probe planetary atmospheres and surfaces, informing exploration.

Abstract

In the late 1990s, the Arecibo Observatory and its planetary radar system were upgraded to increase sensitivity by a factor of 20. This upgrade substantially improved the quality of the data and the ability to observe terrestrial planets, outer planet satellites, planetary rings, and near-Earth objects until the telescope's collapse in 2020. The higher sensitivity allowed radar observations of 889 near-Earth asteroids and comets from 1997 to 2020, compared to the 40 achieved in the previous 30 years, and showed that the population of near-Earth asteroids is heterogeneous, suggesting a wide variety of formation and evolution mechanisms. The planetary radar's ability to see through the atmospheres of Venus and Titan, into the shadows of Mercury and the Moon, and under the surface of the Moon and Mars provided a unique perspective on those bodies that has driven in-situ exploration. No other existing or planned facility matches the sensitivity that Arecibo had.