The loss of the Mars Global Surveyor, a NASA spacecraft that has stopped talking to its controllers, is a sad event. It is impossible not to feel a sentimental 'brave little toaster' bond to a spacecraft that served its Earthly masters so faithfully for so long, and revealed so many wonders. And yet one cliché of loss often used in such situations is, on this occasion, happily inappropriate: this is most definitely not the 'end of an era'. Although the Surveyor is gone, almost ten years to the day after it was launched, the era it ushered in — that of the first continuous, if virtual, human presence at another planet — is still in full swing (see page 526).

For most of the 1980s and 1990s there was hardly any news from Mars. Since the Mars Global Surveyor started doing science in 1999 (getting into the correct orbit was a time-consuming procedure), the flow of data has been uninterrupted. Its cunningly designed camera revealed details of the surface never seen before, including fresh-looking gullies that appear to have been cut by water. Its magnetometer picked up the planet's intriguingly patterned magnetic field. Its laser altimeter provided a topographic map far more accurate than anything that had come before. These instruments on their own would have revolutionized our view of the planet.

But they were not on their own. New spectroscopic capabilities were added by Mars Odyssey in 2002 and by the European Space Agency's Mars Express in 2004, which also provided a radar and a new camera. Information from the ground at two sites was provided by NASA's remarkably enduring Mars rovers, Spirit and Opportunity. This summer the heavyweight Mars Reconnaissance Orbiter joined the squadron with perhaps the most impressive instruments to date. The Phoenix lander is due to join them in a couple of years, and a more capable rover, Mars Science Laboratory, two years after that.

Mars Global Surveyor was the first of a sequence of 'faster, better, cheaper' NASA missions. This approach was subsequently renounced by the space agency, in large part because of the loss of the Surveyor's successors, Mars Climate Orbiter and Mars Polar Lander. But. the idea of a continuous presence has persisted, with the various spacecraft calibrating and complementing each other's results, relaying each other's data when necessary, even taking pictures of each other. The fact that two spacecraft could help search for their fallen comrade is testament to the new age of exploration that the Surveyor inaugurated — even if, on this occasion, their efforts were in vain.