The European Space Agency’s Mars Express spacecraft released an amazing image of our neighboring planet Mars last week (August 5, 2011), showing the Martian north pole at the time of the red planet’s northern summer solstice on May 17, 2010. All the carbon dioxide ice has gone, leaving just a bright cap of water ice.
As on Earth’s northern hemisphere – whose 2011 summer solstice came on June 21 – the summer solstice in Mars’ northern hemisphere marks the longest day of the year on that half of Mars. By tradition, we earthlings mark the beginning of summer at the summer solstice, although no official body has declared it shall be so. Yet the long daylight hours around the summer solstice create noticeable natural effects on both Earth and Mars. In winter and spring on Mars, the Martian north pole is covered by frozen water and frozen carbon dioxide (dry ice). But by the time of the Martian summer solstice, all of the carbon dioxide ice has warmed and evaporated into the planet’s atmosphere, leaving behind the barren red rocks and water ice shown in the photo above.
According to ESA, large bursts of water vapor are occasionally released into the atmosphere from this region on Mars.
The seasonal polar ice that comes and goes on Mars can extend as far south as 45°N latitude and be up to a meter thick.
ESA also says:
Other noticeable features in this image include the Chasma Boreale canyon, coloured deposits and a large dune field.
Chasma Boreale is about 2 kilometers deep, 580 kilometers long and about 100 kilometers wide (about a mile deep, 350 miles wide and 60 miles wide). Its walls allow a perfect view into the strata within the deposits. There are impact craters on the canyon floor, some heavily covered by sand and some partly exhumed.
Dark and light-toned deposits can be seen as a fine and regular covering. The darker sediments have been dropped by the winds during spring dust storms. The patterns are created when the deposits change in quantity according to the seasons.
The polar cap is surrounded by a large dune field, parts of which extend 600 kilometers (400 miles) to the south.
Exciting news. ESA says that the Mars Express spacecraft – which has been orbiting Mars since 2003 – will soon be using its radar to probe the northern polar cap in three dimensions. Since the radar antenna was deployed in mid-2005, the team has been waiting for the right conditions to observe the region, and those optimum conditions should occur in August and September of 2011. The 2D images like the one on this page are so excellent – so stirring to the imagination – that it’s hard for us Mars fans to wait for the 3D! But wait we will – eagerly.
By the way, there are 684 Earth days in a Martian year. It is winter in the northern hemisphere of Mars now, but spring is coming. The northern spring equinox of Mars will come on September 14, 2011, according to the Planetary Society’s Mars calendar.
Bottom line: ESA’s Mars Express spacecraft released an amazing image of our neighboring planet Mars on August 5, showing the summer solstice of May 17, 2010 at Mars’ north pole. The image shows barren red rock at the pole, and water ice. ESA is expecting to use Mars Express to obtain 3D images of the red planet in August and September 2011.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.