By now, many will have the seen the image of Curiosity's descent taken by the Mars Reconnaissance Orbiter (MRO), which captured the rover one minute before its successful landing on Mars' Gale Crater earlier this week. One robot taking a picture of another robot. Above another planet.

Four years ago, the MRO snapped another lander, Phoenix, in a similar situation minutes before it touched down on the red planet. But the two missions are very different. Phoenix got to Mars on a modest US$420-million budget and lasted only five months. Curiosity, at a cost of $2.5 billion, has a rugged design and a nuclear power source that should mean its 400 scientists will be gainfully employed for years to come (see page 137). The rovers' objectives are vastly different, too. Phoenix was stuck scraping for ice in one completely flat spot. Curiosity will climb its 5.5-kilometre-high target — the mountain Aeolis Mons, also known as Mount Sharp — and attempt to unpack the hundreds of millions of years of Martian geological history it contains.

There is something that binds Phoenix, Curiosity and the MRO together besides photography. Since NASA revamped its Mars programme in 2000, it has made a concerted effort to launch regular probes to a Solar System neighbour that is a mere nine-month rocket ride away. Four years before Phoenix, NASA landed the Spirit and Opportunity rovers there. And four years before the 2005 MRO, the agency had launched the Odyssey orbiter. Curiosity and its landing system represent the culmination of technological expertise and lines of scientific enquiry that have been nurtured for more than a decade.

Will the agency get the chance to use these powerful capabilities again? That depends largely on the whims of politicians and the economy, which are both conspiring to dim the future of NASA's Mars programme. It is a good thing that Curiosity could survive for a decade, because it is unlikely that the world will see anything like it for a while.