After wandering in the Martian desert for 25 months, NASA’s Curiosity rover has finally arrived at its promised land: the base of Mount Sharp, the 3-mile-high mound in the middle of Gale Crater.

The arrival marks the beginning of the Mars Science Laboratory rover’s original mission: to read the mountain’s clay-rich lower layers like pages in a history book, pages that could reveal an array of life-friendly environments on the Red Planet.

“We have finally arrived at the far frontier that we have sought for so long,” project scientist and California Institute of Technology geologist John Grotzinger said Thursday.

Getting to Mount Sharp has been a long time coming. The trip was delayed in part by a detour the rover took to look at a promising spot called Yellowknife Bay. Although it cost the team at Jet Propulsion Laboratory about half a year, the gamble paid off; rocks drilled there revealed a smorgasbord of chemical elements that would have been suitable for microbial life, if it ever existed.

Now that the scientists know habitable environments did exist on the Red Planet, part of the next step will be looking for those particular environments that have a higher likelihood of preserving organic molecules, Grotzinger said.

The rover is closing in on a spot known as Pahrump Hills, an outcrop that wasn’t on the original itinerary – an outcome of a detour Curiosity took to avoid sharp rocks that had been damaging its thin wheels.