The Mapimí Silent Zone

A crashed 1970 rocket, and a legend built on the cleanup

Where the Mexican states of Durango, Chihuahua and Coahuila meet lies a stretch of Chihuahuan desert, flat, empty and broken by lone mountain outcrops, that people call la Zona del Silencio, the Zone of Silence. The story says radio signals cannot be received there, compasses spin, plants and animals grow strange, and visitors from the sky come and go. It overlaps the Mapimí Biosphere Reserve, nearly 400,000 hectares of desert, and the ground itself has a long memory: it once lay under the Tethys Sea, which left marine fossils and great salt deposits that labourers still dig with shovels and wheelbarrows.

The name, by one account, dates from 1966, when an expedition from the oil company Pemex under Augusto Harry de la Peña kept losing radio contact. Meteorites helped the legend along. Large ones fell in southern Chihuahua in the 20th century, two of them on the same ranch, in 1938 and 1954, and in 1969 the Allende meteorite came down to the west in a blaze that broke windows and drew scientists from around the world.

Then, at two in the morning on 11 July 1970, an Athena test rocket launched from the Green River complex in Utah toward the White Sands Missile Range in New Mexico went badly off course and crashed in the desert here. It was carrying two small containers of radioactive cobalt-57. The U.S. recovery operation laid a rail spur across the desert, brought in labs and dormitories, and hauled away hundreds of tons of soil, and a local man hired to guard the debris is said to have helped spread the rumours that grew out of it: magnetic anomalies, mutations, extraterrestrials. Locals have used the stories to bring in tourists ever since.

At the zone's peak, crowds of zoneros came looking for aliens. The stories are colourful. A state official who investigates UFOs speaks of tall blond beings who appear to lost travellers, ask only for water in perfect Spanish and say they come from "above"; a rancher on the zone's edge, Benjamin Palacios, says he lost two hours in a ring of light as a boy. Believers blame buried magnetite and meteorite debris for the radio trouble, yet many visitors find their radios and compasses working perfectly well, to which guides reply that the zone moves.

The reserve itself is no legend. It hosts a research station and scientists drawn by its wildlife, among them the threatened Bolsón tortoise, North America's largest land reptile. The country is remote, riddled in places with old mine shafts, and not for wandering alone.