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Happy (Mars) New Year

While 2023 is still six days away here on Earth, Year 37 has arrived on Mars with the Spring Solstice.

Posted 2022-12-26T22:18:11+00:00 - Updated 2022-12-26T22:18:11+00:00

About 1000 Viking Orbiter red- and violet-filter images have been processed to provide global color coverage of Mars at a scale of 1 km/pixel. Individual image frames acquired during a single spacecraft revolution were first processed through radiometric calibration, cosmetic cleanup, geometric control, reprojection, and mosaicing. We have produced a total of 57 "single-rev" mosaics. All of the mosaics are geometrically tied to the Mars Digital Image Mosaic, a black-and-white base map with a scale of 231 m/pixel. We selected a subset of single-rev mosaics that provide the best global coverage (least atmospheric obscuration and seasonal frost); photometric normalization was applied to remove atmospheric effects and normalize the variations in illumination and viewing angles. Finally, these normalized mosaics were combined into global mosaics. Global coverage is about 98% complete in the red-filter mosaic and 95% complete in the violet-filter mosaic. Gaps were filled by interpolation. A green-filter image was synthesized from an average of the red and violet filter data to complete a 3-color set. The Viking Orbiters acquired actual green-filter images for only about half of the Martian surface. The final mosaic has been reprojected into several map projections. The orthographic view shown here is centered at 20 degrees latitude and 60 degrees longitude. The orthographic view is most like the view seen by a distant observer looking through a telescope. The color balance selected for these images was designed to be close to natural color for the bright reddish regions such as Tharsis and Arabia, but the data have been "stretched" such that the relatively dark regions appear darker and less reddish that their natural appearance. This stretching allows us to better see the color and brightness variations on Mars, which are related to the composition or physical structure of the surface materials, which include volcanic lava flows, wind- and water-deposited sedimentary rocks, and (at the poles) ice caps. The north polar cap is visible in this projection at the top of the image, the great equatorial canyon system (Valles Marineris) below center, and four huge Tharsis volcanoes (and several smaller ones) at left. Also note heavy impact cratering of the highlands (bottom and right portions of this mosaic) and the younger, less heavily cratered terrains elsewhere. (Image: NASA/JPL)

Tony Rice

, NASA Ambassador

Mars reaches its spring equinox today... er.... tosol, December 26, 2022, beginning year 37 on the red planet. Scientists have used the spring solstice two two decades to mark the beginning of the planet's year which lasts 668.6 sols or about 687 Earth days.

A year on Mars is almost twice that of Earth (NASA JPL)

Mars has an axial tilt so it has seasons like Earth. But Mars' orbit is less circular so the length of those seasons is uneven.

Summer begins in the northern hemisphere of Mars on July 12, 2023 followed by autumn on Jan 12, 2024, then winter on June 7, 2024. Mars Year 38 begins on November 12, 2024 with the next spring equinox

Mars is further from the Sun so its year is longer but it's orbit is also less circular than's Earth's making the length of seasons less even as well (NASA/JPL, Rice)

1955 was selected to begin counting Mars years when Raleigh native, Dr. Todd Clancy, came up with the method to ease comparison of data from the Mariner 9 (1971-72), Viking (mid 1970s), and Pathfinder (1997) missions along along with ground based observations from the National Radio Astronomy Observatory in Kitt Peak, Arizona in a 2000 study of temperature data.

Clancy earned a B.S. in Geology from UNC before going on to a PhD In Planetary Science from Cal Tech. Today he works today as Senior Research Scientist for the Space Science Institute from his home in Bald Head Island, where he continues to study weather and climate of Mars and Venus.

His paper describes the April 11, 1955 spring solstice as an arbitrary one to begin Mars year 1. But it encompasses the data set in his paper, also includes Mariner 4’s historic flyby of Mars in 1965, but most importantly includes the great Mars dust storm of 1956 where some of the first detailed data about planet encircling dust storms was gathered.

Today we know continent sized dust storms can be an annual event on Mars. About every 3 Mars years (5.5 Earth years) these storms tend to grow to encircle the planet. While winds top out at around 60 mph, with an atmosphere about 1% that of Earth’s you would barely feel it if standing on the surface o the red planet.

The bigger problem is the dust, about the consistency of flour, which is suspended in the atmosphere, completely blocking the Sun. It is also electrostatically charged which can harm the rovers and landers operating on the surface, especially as it is deposited and tends to stick on solar panels limiting power production.

That dust recently ended the four year mission of the InSight lander which revealed details to scientists about the interior of Mars from the crust to the core and recorded more than 1,300 Mars quakes.