MRO MARCI Weather Report for the week of
19 November 2007 – 25 November 2007

Martian Weather Between 19 November 2007 and 25 November 2007:

This is our first in a planned series of weekly Mars weather reports from the Mars Reconnaissance Orbiter (MRO) Mars Color Imager (MARCI) team. Under nominal MRO operating conditions, the MARCI acquires a global view of the red planet and its weather patterns every day. Please click and play the Quicktime movie (.mov file) to see how the weather on Mars changed over the past week.

At this time, only a couple weeks remain for the northern winter and southern summer seasons, as the equinox— and the start of a new Mars year—will occur on 9 December 2007. The small southern perennial polar cap (also known as the ‘residual cap’) has begun to disappear from view as the long polar night approaches. In the northern hemisphere, the seasonal polar cap, composed mostly of frozen carbon dioxide (dry ice), has reached its greatest equatorial extent, extending as far south as about 55° North latitude. The large temperature contrasts at the edge of the receding northern cap help to generate large local dust storms that are similar in shape and form to terrestrial low-pressure storm systems. Such martian storms can persist for up to three martian days (sols). Last week, these storms were observed moving eastward at 10 to 20 meters per second (22 to 44 miles per hour). Other local dust storms occurred sporadically over northern Amazonis and at southern mid-latitudes. Water ice clouds (bluish-white in the movie) were seen over some of the Tharsis volcanoes and near the edge of the northern seasonal polar cap.

Earlier Mars Weather Reports are available HERE.

About the Quicktime Movie:
The movie (a .mov file that you can click and play, above) was generated from images obtained last week by the Mars Color Imager (MARCI) onboard the Mars Reconnaissance Orbiter (MRO). A total of about 273 MARCI images, taken in three of the camera’s seven color filter bands (420, 550, and 600 nanometer wavelengths), were map projected and mosaiced together to produce seven false-color daily global maps. These maps were then projected onto a sphere with north at the top and east to the right and with the mid-afternoon vantage point of an observer in the orbital plane (the imaginary plane that the planet draws out as it circles the Sun). Black areas in the movie are the result of data drops or high angle roll maneuvers by the spacecraft that limit the camera’s view of the planet. Equally-spaced blurry areas that run from south-to-north (bottom-to-top) result from the high off-nadir viewing geometry, a product of the spacecraft’s low-orbit, 250 km x 316 km (155 miles x 196 miles). The movie is rendered at a lower resolution than the intrinsic 1–2 km nadir resolution that the MARCI provides, so that it is practical to view and share via the Internet. The small white circles on these images of Mars indicate the locations of the two Mars Exploration Rovers, Opportunity (on Meridiani Planum) and Spirit (in Gusev Crater). Other locations on Mars referenced in the weather report can be found by referring to the map below. Note that the still image of Mars depicted at the top of this page is a single frame from the Quicktime movie. This single image is from the week covered by the current weather report and the Quicktime movie.

Malin Space Science Systems, Inc., San Diego, California, U.S.A.