loading page

Hexagonal Prisms Form in Water-ice Clouds on Mars, Producing Halo Displays Seen by Perseverance Rover
  • +13
  • Mark T Lemmon,
  • Daniel Toledo,
  • Víctor Apéstigue,
  • Ignacio Arruego,
  • Michael J. Wolff,
  • Priyaben Patel,
  • Scott D. Guzewich,
  • Tony Colaprete,
  • Alvaro Vicente-Retortillo,
  • Leslie Tamppari,
  • Franck Montmessin,
  • Manuel de la Torre Juarez,
  • Justin N. Maki,
  • Timothy McConnochie,
  • Adrian Jon Brown,
  • James F Bell
Mark T Lemmon
Space Science Institute

Corresponding Author:[email protected]

Author Profile
Daniel Toledo
Instituto Nacional de Tecnica Aeroespacial (INTA)
Author Profile
Víctor Apéstigue
National Institute of Aerospace Technology (INTA)
Author Profile
Ignacio Arruego
INTA
Author Profile
Michael J. Wolff
Space Science Institute
Author Profile
Priyaben Patel
University College London
Author Profile
Scott D. Guzewich
NASA Goddard Space Flight Center
Author Profile
Tony Colaprete
NASA Ames Research Center
Author Profile
Alvaro Vicente-Retortillo
Centro de Astrobiología (INTA-CSIC)
Author Profile
Leslie Tamppari
Jet Propulsion Laboratory
Author Profile
Franck Montmessin
LATMOS CNRS/UVSQ/IPSL
Author Profile
Manuel de la Torre Juarez
Jet Propulsion Laboratory/California Institute of Technology
Author Profile
Justin N. Maki
Jet Propulsion Laboratory, California Institute of Technology
Author Profile
Timothy McConnochie
Space Science Institute
Author Profile
Adrian Jon Brown
Plancius Research
Author Profile
James F Bell
Arizona State University
Author Profile

Abstract

Observations by several cameras on the Perseverance rover showed a 22° scattering halo around the Sun over several hours on the morning of sol 292 (15 December 2021). Such a halo has not previously been seen off Earth. The halo occurred during the aphelion cloud belt season and the cloudiest time yet observed from the Perseverance site. The halo required crystalline water-ice cloud particles in the form of hexagonal columns large enough for refraction to be significant, at least 11 µm in diameter and length. Near 44 km altitude, fall speeds would have been 0.3-1 m/s for the smallest allowed particles. Over the 3.3-hour duration of the halo, particles could have fallen 3-12 km, causing downward transport of water and dust. Halo-forming clouds are likely rare due to the high supersaturation of water that is required but may be more common in northern subtropical regions during mid-northern summer.