Cosmic dust impacts on the Hubble Space Telescope

Abstract

Exposure of the Hubble Space Telescope to space in low Earth orbit resulted in numerous hypervelocity impacts by cosmic dust (micrometeoroids) and anthropogenic particles (orbital debris) on the solar arrays and the radiator shield of the Wide Field and Planetary Camera 2, both subsequently returned to Earth. Solar cells preserve residues from smaller cosmic dust (and orbital debris) but give less reliable information from larger particles. Here, we present images and analyses from electron, ion and X-ray fluorescence microscopes for larger impact features (millimetre- to centimetre-scale) on the radiator shield. Validated by laboratory experiments, these allow interpretation of composition, probable origin and likely dimensions of the larger impactors. The majority (~90%) of impacts by grains greater than 50 μm in size were made by micrometeoroids, dominated by magnesium- and iron-rich silicates and iron sulfides, metallic iron-nickel and chromium-rich spinel similar to that in ordinary chondrite meteorites of asteroid origin. Our re-evaluation of the largest impact features shows substantially fewer large orbital debris impacts than reported by earlier authors. Mismatch to the NASA ORDEM and ESA MASTER models of particle populations in orbit may be partly due to model overestimation of orbital debris flux and underestimation of larger micrometeoroid numbers. This article is part of the theme issue ‘Dust in the Solar System and beyond’.

Exploring the universe through dusty visions

“…The paper emphasizes a measurement campaign to investigate the origin of these dust swarms by future space missions with dust detectors such as JAXA/DLR DESTINY+ mission. The sixth paper by Kearsley et al [23] discusses the hypervelocity impact of cosmic dust particles onto the Hubble Space Telescope (HST) in low-Earth orbit. In contrast to the previous three papers, the research here focuses on larger particles (millimetre to centimetre scale) incident upon the radiator shield of HST.…”