Late, once again! - Sol 104 (GIF-Movie; credits: NASA/JPL-Caltech/University of Arizona/Texas A&M University)

Con quattro giorni di ritardo rispetto alla pubblicazione operata da Lunar Explorer Italia di un filmato GIF prodotto dal Dr Barca e relativo al MEDESIMO fenomeno, anche i nostri Amici di Pasadena hanno pensato di elargirci il loro filmatino che ritrae un Dust Devil mentre passa non lontano dal Phoenix Lander.
La NASA ci legge? Ma certo che ci legge, e noi ne siamo onorati! E comunque sia, vedere che alla NASA arrivano (quantomeno nelle pubblicazioni divulgative) spessissimo - anzi: quasi sempre - DOPO di noi, è comunque una fonte di enorme soddisfazione: umana e professionale.

Ed eccoVi la caption NASA al filmino:"The Surface Stereo Imager on NASA's Phoenix Mars Lander caught this Dust Devil (a.k.a.: "DD" or "DDs", for the plural) in action West of the Lander in four frames shot about 50 seconds apart from each other between 11:53 and 11:56 M.L.T. Sol 104, or the 104th Martian day of the mission - such as Sept. 9, 2008).
DDs have not been detected in any Phoenix images from earlier in the Mission, but at least six were observed in a dozen images taken on Sol 104.
Dust Devils are whirlwinds that often occur when the Sun heats the surface of Mars, or some areas on Earth. The warmed surface heats the layer of atmosphere closest to it, and the warm air rises in a whirling motion, stirring dust up from the surface like a miniature tornado.
The DD visible in this sequence was about 1 Km (about 3300 feet) from the Lander when the first frame was taken, and had moved to about 1700 meters (about 5600 feet) away by the time the last frame was taken about two and a half minutes later. The DD was moving Westward at an estimated speed of 5 meters per second (such as abou 11 mph), which is similar to typical late-morning wind speed and direction indicated by the Telltale Wind Gauge - such as the Anemomether) on Phoenix.

This Dust Devil is about 5 meters (16 feet) in diameter. This is much smaller than DDs that have been observed by NASA's Mars Exploration Rover Spirit much closer to the Equator. It is closer in size to DDs seen from orbit in the Phoenix Landing Region, though still smaller than those..
The image has been enhanced to make the Dust Devil easier to see. Some of the frame-to-frame differences in the appearance of foreground rocks is because each frame was taken through a different color filter".