|Rio Tinto, Huelva, Spain|
There are...sites in Spain that have an other-worldly feel. Consider those Darth Vader lookalikes atop Gaudi's La Pedrera in Barcelona, or the lava-made moonscapes in Tenerife.
Even some Marbella mansions might qualify for extraterrestrial status.
Tourists joke about its Martian credentials as they photograph the rust-coloured water and craters, carved by centuries of mining.
But scientists take the Rio Tinto seriously. For them, this hostile turf tinged by oxidised iron is a convenient substitute for the Red Planet. In fact, it boasts so many Martian properties that two space agencies even conducted a "mission" there last month, including a simulated Mars walk.[...]
A bridge dating from the Roman Empire still spans the Rio Tinto.
The Rio Tinto basin is...one of about 20 strange sites around the world – from the Arizona desert to the volcanic Krafla region of Iceland – where scientists can test their equipment on unearthly landscapes.
The Rio Tinto area looks like the red planet because it contains a high concentration of the minerals that are abundant on there, such as iron, sulphur and copper.
"Iron is what gives the Red Planet its colour – a lot of the surface of Mars basically rusted away," Mr Groemer said.
The rich ore has attracted miners since pre-Roman times. In the 19th-century, large British mining companies began extracting copper, silver, sulphur and gold from the Rio Tinto on a large scale, leaving an unearthly crater in their wake – as well as a village with well-trimmed gardens built for British employees. The mines have closed, and the only trace of human activity is the turn-of-the-century tourist train that chugs by the old rail lines, and a museum, housed in the employee hospital, that recalls "5,000 years of mining history".
The river itself is extremely acidic, with a PH of 0.7 compared to the neutral 7 of ordinary water. It springs from the ground and is isolated from other water sources by a geological fault.
Signs warn not to drink the water. "You don't even want to wash your hands in it," Mr Groemer said.
Read more in The Independent.But a special form of bacteria has managed to thrive there. Last year, laboratory tests by scientists in Madrid showed that the bacteria could survive in extreme conditions similar to those found in the Martian subsoil, fuelling hopes of life-seekers.
Huelva Tourist Information (English)
Minas de Rio Tinto Mining Museum (English)
Parque Minero de Riotinto (Spanish)