Ten years at Mars: new global views plot the Red Planet’s history | WPN World People News

New global maps of Mars released on the 10th anniversary of the launch of ESA’s Mars Express trace the history of water and volcanic activity on the Red Planet, and identify sites of special interest for the next generation of Mars explorers.

The unique atlas comprises a series of maps showing the distribution of minerals formed in water, by volcanic activity, and by weathering to create the dust that makes Mars red. They create a global context for the dominant geological processes that sculpted the planet.

Mars Express mission highlights.

The maps were built from ten years of data collected by the OMEGA mineralogical mapper on Mars Express, which determines the mineral composition of the martian surface by analysing the spectrum of reflected sunlight.

“The history of Mars is encoded in its minerals,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration.

“These new global views, made possible thanks to the longevity of ESA’s Mars Express mission, are helping us to unlock the secrets of 4.6 billion years of planetary evolution.

“The atlas released will help to determine future landing sites for the next generation of Mars landers and rovers, and identify sites of special interest for future manned missions, helping to keep Europe at the forefront of planetary exploration.”

Each map represents a different chapter in the story of geological evolution on Mars.

Maps showing the distribution of minerals formed in water
The first map shows individual sites of hydrated minerals – ‘phyllosilicates’ and hydrated salts that form only in the presence of water. These are primarily seen in the most ancient cratered terrain dating back to over four billion years ago, suggesting that Mars sustained surface and subsurface liquid water during its first few hundred million years, potentially providing conditions favourable to early life.

Maps showing the distribution of minerals formed by volcanic activity
The next two maps showing the minerals olivine and pyroxene tell the story of volcanism, with differences in the chemical composition of the solidified lavas yielding clues as to the evolution of the temperature and pressure inside the planet.

Olivine and pyroxene are the two primary minerals in basalt that form when lava solidifies. Basalt characterises the crust of Mars as well as oceanic crust on Earth and the volcanic ‘seas’ on the Moon.

Some of the most pristine, magnesium-rich olivines exposed on the surface of Mars today are found around impact craters that have excavated samples of very ancient mantle from beneath the crust.

Olivine-rich surfaces are associated with a global lava-flooding event around 3.7 billion years ago, when magma erupted onto the surface through fractures in the floors of impact craters, similar to the way in which the Moon’s large impact basins were flooded with volcanic lava. Only a few traces of this global event remain, with subsequent geological activity overprinting the signature.

Pyroxenes are particularly widespread in the cratered highlands, pointing to some of the most ancient portions of the planet’s crust. In the smooth northern plains, the pyroxenes reflect the eruption of more evolved lavas compared to the pristine olivines.

Maps showing the distribution of dust created by weathering
Dust obscures much of the underlying rock on Mars, but it is very closely related to ferric oxide, a mineral phase of iron found all over the planet, with greatest abundances in the northern lowlands and the volcanic province of Tharsis.

The Red Planet’s dust is thought primarily to result from chemical reactions with the atmosphere, causing the iron-rich rocks to ‘rust’ slowly over billions of years, giving Mars its distinctive hue.

Weathering and erosion from past glacial activity and impact events, as well as dust storms, winds and freezing and thawing cycles, contribute to the continued production of fine-grained dust.

“Collectively, these mineral maps provide unique records of the planet’s evolution through time. They exhibit the role water and volcanic processes played over the entire planet, spanning geological aeons,” says Jean-Pierre Bibring, Principal Investigator for OMEGA.

Source: European Space Agency