This Amazing Mars
As an avid Mars buff I often stumble upon some pretty unusual photos of Mars or some pretty cool illustrated scientific facts. Some of these pics are so exciting, so contrary to the ‘barren red globe’ notion of Mars that I wish I could run outside and show them to every passer-by. Unlike the average passer-by, the online community will surely appreciate more my humble efforts to educate about our neighbour planet.

The image above shows the so-called Hephaestus Fossae, a network of ‘canals’ to the west of Elysium Planitia, taken by the high-resolution camera on board the Mars Express orbiter. This single photograph provides a broad overview of a good chunk of geological history of Mars. The surface appears to have been formed by lava flows from the nearby Elysium volcano as evidenced by the contemporaneous lava tubes, vestiges of those ‘hot’ times, in the lower right section of the image. Later there was a deep river that flew for about 100 km. This river was unusual in that some of its flow disappeared underneath the lave tubes, thus becoming a subterranean river. The large-scale version of the image should give a better idea (size 1.4 mb).

Later on, when the climate of Mars changed and the surrounding area was locked in permafrost, a meteorite landed slap bang in the riverbed, creating a 20 km crater. The rims of the crater opened up like petals – a unique feature of Martian craters. Such ‘petals’ appeared even in those places where meteorites hit water ice-rich surface. This whole area might have been part of Mars’s Northern Ocean floor (and, unsurprisingly, it was an icy one!), and after the onset of frosty weather, the soil was gripped by permafrost.

The next image shows an intercation between the frozen ocean and volcanic lava (altitude map based on Mars Express image).

Ceraunius Tolus is a 4.5 km high volcano which towers in the northen part of the Tharsis volcanic region (image in natural colour). It is the fourth element (alongside its companion volcano Uranius Mons) in a chain of shield volcanoes, the others being Ascraeus Mons, Pavonis Mons and Arsia Mons.

The location of the four huge shield volcanoes nearly in a straight line is an argument in support of a possible continental drift in the past, but so far there is no direct evidence of a tectonic plate drift, as there are no known spreading and subdiction zones on the planet. However, an explanation is lacking for such a strange pattern, and there is no alternative to it at present.

Of the four volcanoes Ceranius Tolus is the smallest and, possibly, the youngest. As its neighbour, Uranius Mons, it might be a testament to a hot lava flow trying to push to the surface. One of its latest eruptions occurred when the Northern Ocean surrounding the volcanoes had already frozen, turning into dust-covered ice deposits. The last lava flow melted an oval-shaped lake in this ice, with mud slides forming on both sides of it.

Scientists were sceptical for a long time that there could be lots of ice on Mars lying extremely close to the surface. Luckily, a look from the skies helped to settle the issue.

This photo by Mars Reconaissance Orbiter shows near-surface ice-deposits at latitude 44 in the Northern hemisphere (full size, 6 Mb). The high-resolution HiRise camera shoots in extended colour, which is why white ice appears blueish and grey surface greenish. Further observation of this meteorite crater showed that ice cannot remain long on the surface as it will evaporate within a few days. However, ice can stay put for millions of years under a layer of dust where it cannot warm up to 0 C, awaiting an advent of global warming or of colonists from Earth.
 But not all water on Mars lies quietly under the surface. Water could have got pretty out of hand millions of years ago on Mars (image by MRO).

The fantastic glaciers of Hellas Planitia have only recently received the attention they deserve. It took scientists a long time to recognize that they were no lava, as only water ice is capable of being viscous on Mars. Several climate models have been proposed to explain how these glaciers came to be there. According to the current hypothesis, Mars experienced significant changes of its axial tilt in its past, which occasionally exceeded 45 degrees for periods of several hundred thousand years (Mars’s current axial tilt is close to the Earth’s at 25.19 degress). This was caused by Mars lacking an outrigger to balance it such as the Moon in the Earth-Moon system. When the axial tilt increased, the existing polar caps got coated in dust and the new Poles of Cold, which did not coincide with the geographical poles, began to accumulate ice. The South Pole of Cold was located approximately in the eastern part of Hellas Planitia at the times of these drastic tilts. Once formed, a glacier begins to slowly crawl down the mountain slope into the valley below, tugged by gravity. In this sense Martian glaciers differ little from their terrestrial counterparts. As it moves, the glacier is capable of creating some very unusual relief features, like the ones you can see in the image.

The origin of some craters on Mars is still a mystery to planetologists. The biggest crater is the feature known as Orcus Patera (full size, 45 Mb, tiff).

The term ‘patera’ is a sobriquet reserved for volcanic craters and calderas on Mars. However, Orcus crater, 380 km in diameter, bears no traces of volcanism, even though it is filled with a smooth layer of lava. There are several hypothesis explaining its origin. The tectonic hypothesis says that it used to be a regular round-shaped crater, which later got squeezed on two sides by tectonic movement, which changed its shape to oval. This exotic idea is an attempt to offer an alternative explanation to the fact that the crater was formed by an oblique hit by a meteorite body that did not disintegrate on impact, but simply bounced off from the surface. As a rule, huge amounts of energy are emitted by falling space bodies as large as this one, which causes the meteorite to fall apart. In this case the rock 80-100 km in diameter entered the Martian atmosphere, ploughed the canyon and bounced off on a new trajectory, unharmed. The impact energy melted the rocky top layer and Orcus Patera turned into a gigantic lava lake, whereas the space perp left no visible traces after itself. An iron meteorite could have probably survived an impact of such force, but we are yet to get evidence of it.

This elongated crater type is not a standalone feature, either on Mars, or on other bodis of the Solar System. That said, it is by far the largest such structure to have been discovered.

I was sure not the only one thinking ‘this can’t be true!’ when I saw this image for the first time (full size, 0.4 Mb).

This is not Photoshop-edited, nor is it some prop for the Dune movie. This is an actual surface feature on Mars’s North Pole, as photographed by the Mars Odyssey orbiter. Even NASA, which is usually very reserved inventing titles for its photos, could not help indulging themselves by calling this place Reptilian Dunes. Despite its exotic appearance, this is only sand dunes, shaped into this fantastic form by polar winds.

This is not the only wow photo from Mars, I’ve got so many more to surprise you. But it’s time to wrap up for now. If you liked this article, I’ll be happy to write more about such things in the future. Please, subscribe to my profile in order not to miss any new stuff!