Examinando por Autor "Donaldson, Chris"

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Acceso Abierto
Detection of visible-wavelength aurora on Mars
(Science, 2025-05-14) Knutsen, Elise; McConnochie, Timothy; Lemmon, M. T.; Donaldson, Chris; Francis, Raymond; Legett, Carey; Viet, Shayla; Soret, Lauriane; Toledo, D.; Apéstigue, Víctor; Witasse, Olivier; Montmessin, F.; Jolitz, Rebecca; Schneider, Nicolas; Tamppari, L. K.; Cousin, Agnes; Wiens, Roger; Maurice, Sylvestre; Bell, James; Forni, Olivier; Lasue, Jeremie; Pilleri, Paolo; Bertrand, T.; Patel, P.; Schröder, Susanne; Curry, Shannon; Lee, Christina; Rahmati, Ali; National Aeronautics and Space Administration (NASA); Belgian National Fund for Scientific Research; Jet Propulsion Laboratory; Norges Forskningsråd
Mars hosts various auroral processes despite the planet’s tenuous atmosphere and lack of a global magnetic field. To date, all aurora observations have been at ultraviolet wavelengths from orbit. We describe the discovery of green visible-wavelength aurora, originating from the atomic oxygen line at 557.7 nanometers, detected with the SuperCam and Mastcam-Z instruments on the Mars 2020 Perseverance rover. Near–real-time simulations of a Mars-directed coronal mass ejection (CME) provided sufficient lead-time to schedule an observation with the rover. The emission was observed 3 days after the CME eruption, suggesting that the aurora was induced by particles accelerated by the moving shock front. To our knowledge, detection of aurora from a planetary surface other than Earth has never been reported, nor has visible aurora been observed at Mars. This detection demonstrates that auroral forecasting at Mars is possible, and that during events with higher particle precipitation, or under less dusty atmospheric conditions, aurorae will be visible to future astronauts.
Acceso Abierto
First detection of visible-wavelength aurora on Mars
(Europlanet, 2024-07-03) Wright Knutsen, Elise; McConnochie, Timothy; Lemmon, M. T.; Tamppari, L. K.; Viet, Shayla; Cousin, Agnes ; Wiens, Roger; Francis, Raymond; Donaldson, Chris ; Lasue, J.; Forni, Olivier; Patel, P.; Schneider, Nick; Toledo, D.; Apéstigue, Víctor
Auroras are hallmarks of the interaction between solar particles and the atmosphere of planets. Martian aurora was first discovered in 2005, since then, four different types have been identified: localized discreet aurora (Bertaux et al., 2005), global diffuse aurora (Schneider et al., 2015), dayside proton aurora (Deighan et al., 2018), and large-scale sinuous aurora (Lillis et al., 2022). All previous detections have been made in the UV from orbit. Here we present, from observations with the SuperCam and MastCam-Z instruments on the Mars 2020 Perseverance rover, the first detection of aurora from the Martian surface and the first detection of the green 557.7 nm atomic oxygen auroral emission on Mars. This is the same emission line that is familiar from terrestrial aurora. Charged particles accelerated by interplanetary coronal mass ejections (ICMEs) or solar flares are referred to as solar energetic particles (SEPs) (Reames, 1999). Diffuse aurora is strongly correlated with SEP events. ICME-accelerated SEPs travel nearly radially, as opposed to flare-accelerated SEPs which follow the Parker spiral. If the solar source region is identified, ICME-accelerated SEP events at Mars, and thus diffuse aurora, can be forecasted. The dynamic nature of rover planning and operations allows for a reactive observation strategy that takes advantage of such forecasts. We made several attempts, starting in May 2023, to react to SEP events and observe with the M2020 rover (Farley et al., 2020) instruments at times when we believed the likelihood of emission to be highest. Our fourth attempt, in March 2024, yielded the positive detection reported here.