Science & Exploration

Iani Chaos and Valles Marineris

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ESA / Science & Exploration / Space Science / Mars Express

Iani Chaos and the upper reaches of Ares Vallis

This movie was produced using images from the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft. Its first part shows a simulated flight over the upper reaches of Ares Vallis, a large outflow channel on Mars, and parts of its source region, Iani Chaos.

Ares Vallis is one of the biggest drainage systems on Mars. From its source region in Iani Chaos near the equator, the valley winds north-west for about 1400 kilometres through the ancient Xanthe Terra highlands Eventually, it ends up in the northern lowland plains of Chryse Planitia.

The flanks of the deep canyon, rise up to 2000 metres from the valley floor. The morphology of the valley shows drainage patterns of many kinds: flow features along with isolated streamlined islands and terraces.

Very likely, large amounts of water have flown here episodically during Mars’s past. Ares Vallis is thought to have formed thousands of millions of years ago.

Iani Chaos itself is a depression of approximately 200 km by 180 km in size. At its northern side the depression wall is eroded away to form the beginning of Ares Vallis.

Inside Iani Chaos, a chaotic distribution of individual blocks of rock and hills form a disrupted pattern. These ‘knobs’ are several hundred metres high. Scientists suggest that they are remnants of a pre-existing landscape that collapsed after possible cavities had formed beneath the surface.

Ice stored in these cavities may have been molten by volcanic heat, and the water then discharged to the north – while the highland surface collapsed as a consequence.

The simulated flight from north to south is based on a digital-terrain model derived from the stereo channels of Mars Express HRSC. Three HRSC image strips, acquired from an altitude of approximately 280 km altitude, have been matched into a mosaic to obtain a wide regional perspective. The original resolution is 12.5 metres per pixel.

Mountain ranges in central Valles Marineris

The second part of this movie shows a simulated flight over high altitude features in the central part of Valles Marineris.

The 'Valley of the Mariner' are named for the US Mariner 9 orbiter which first imaged this huge canyon system in 1971. From west to east, Valles Marineris stretches over 4000 kilometres along the Martian equator It is the biggest known canyon in the Solar System: the valley floor reaches a depth of 11 km. On average, other Martian valleys are only 7 km deep.

Image data used for this movie of the central part of Valles Marineris are from two Mars Express orbits, on 24 April and 2 May 2004 respectively, acquired from an altitude of about 500 km, resulting in image resolutions of approximately 25 metres per pixel.

Here the Valles Marineris complex has its largest north-south extension. Several sub-valleys are divided by high mountain ranges, running in parallel to the entire canyon system. The two valleys seen here are named Ophir Chasma and Candor Chasma, and are each about 200 km wide. The area shown in the movie is about the size of the southern half of Germany.