The shape and spin state of (275677) 2000 RS11 from ground-based radar and optical observations

Near-Earth asteroid (275677) 2000 RS11 was observed over 5 days in March 2014 with both the Arecibo (2380 MHz, 12.6 cm) and Goldstone (8560 MHz, 3.5 cm) planetary radar systems. The continuous-wave spectra and delay-Doppler images collected revealed a sub-km-sized object with a strongly bifurcated shape. We used these radar observations, in combination with 7 optical lightcurves collected in 2014 and one lightcurve from 2023, to create a comprehensive shape and spin-state model for RS11. We find a rotation period of P = (4.445+-0.001) hours around a pole of lambda = (225+-80) and beta = (-80+-9) relative to the plane of the ecliptic. The shape of RS11 is unusual in that it does not resemble many of the other near-Earth asteroids modelled with ground-based radar. Whilst RS11 consists of a largely spherical, smaller lobe attached to an elongated, larger lobe via a narrow neck, the smaller lobe is not aligned with the long axis of the larger lobe, but is closer to the larger lobe's shortest principal axis. In combination with a large concavity observed on the outer face of the larger lobe, this may point to an unusual formation or event in the object's past. We estimate that RS11 has an geometric albedo of (0.16+-0.06) and a radar albedo between 0.08 and 0.16. Analysis of its gravitational environment reveals that for standard S-type asteroid densities, we would not expect rotational instability and it is possible for RS11 to be a low tensile strength rubble-pile asteroid.

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Ground-Based Radar Tracking of Near-Earth Objects With VLBI Radio Telescopes: 2024 MK Test Case

The Southern Hemisphere Asteroid Research Project is an active and informal entity comprising the University of New South Wales, the University of Tasmania, the University of Western Australia, and the Curtin University, which performs asteroid research in collaboration with federal agencies, including the Commonwealth Scientific and Industrial Research Organisation and the National Aeronautics and Space Administration (JPL). Since 2015, we have used the Australian infrastructure to characterize more than 50 near-Earth asteroids through bistatic radar observations. On 29 June 2024, we used four very long baseline interferometer (VLBI) radio telescopes to follow the close approach of 2024 MK to the Earth. In this paper, we describe the detections and the analysis of VLBI and howthese observations can help to improve the understanding of its composition and orbit characterization.

Hayabusa2 extended mission target asteroid 1998 KY26 is smaller and rotating faster than previously known - Nature Communications

Asteroid 1998 KY26 is the target of Hayabusa2 extended space mission. Here, authors show that it is smaller and rotates faster than known.

Abstract EPSC-DPS2025-845