Ten years ago NASA launched a pair of robots into space. Those robots began a journey of discovery that helped change our models of how a specific planet evolved over the past billion years…Mars.
Among the discoveries made, was a deposit of clay-like material, which can only form with extensive water exposure. That was a hoped-for and unexpected bonus.
The robots were expected to last perhaps – at best – half a year.
Their primary mission was designed for 90 days – 3 months. Anything beyond this was a bonus, an extended mission.