Life on Mars?

The fascination with Mars and life led to attempts to find life on Mars. The first serious attempt was with the Viking landers launced in the 1970s. There were dedicated biological experiments on board designed to search for Law As We Know It (LAWKI). That is, the Viking experiments were designed to detect life based on the example we know best, that is, life on Earth. Is this sensible?

More recent missions to Mars have greatly improved our picture of the Martian surface and the conditions on Mars today. Curiosity was launched on Nov 26, 2011 reaching Mars on Aug 5, 2012 (landing in Gale crater).

A tantalizing (but inconclusive) result was published in the 1990s. A Martian meteorite was discovered on Earth in the Allan Hills of Antarctica. Meteorite ALH 84001 was argued to bear evidence of past life on Mars: