Europe arrives at Mars; Beagle 2 does not call home

Mars Express released Beagle 2 on 19 December 2003 and then braked itself into orbit on Christmas morning. It was ESA's first mission to another planet, and it got there fast and cheap by planetary-mission standards: about four years from go-ahead to launch, built on Rosetta's structure, with several of its eight instruments rebuilt from designs orphaned when Russia's Mars 96 came back down in 1996. It launched on a Soyuz-Fregat from Baikonur on 2 June 2003.

The orbiter worked, and is still working. Its OMEGA spectrometer found phyllosilicates — clays — in the oldest terrain, minerals that on Earth form where water sits in contact with rock at something near neutral pH, and that reading split Martian history into an early wet chapter and a later sulfurous, acidic one. Its MARSIS radar, whose two twenty-metre booms sat folded for eighteen months while engineers argued about whether they would whip back into the spacecraft on release, sounded kilometres down into the polar caps. Mars Express passed its 687-day design life more than two decades ago; ESA has confirmed its operations to the end of 2026 and provisionally to the end of 2028, partly so it can support Japan's MMX sample-return mission to Phobos.

Beagle 2 did not work, and for eleven years nobody could say why. It was a 33-kilogram clamshell about a metre across when open, pushed through by Colin Pillinger of the Open University on a budget partly assembled from sponsorship, carrying a mass spectrometer to hunt for methane and carbon isotope ratios, a rock grinder, and a burrowing mole to fetch soil from beneath a boulder. It was supposed to call Mars Odyssey on Christmas Day. Jodrell Bank heard nothing. Mars Express heard nothing in January. The management board declared it lost on 6 February 2004, and the inquiry that followed could not identify a cause; it criticised the thinness of the funding and the management arrangements around it.

In January 2015, Michael Croon, a retired Mars Express operations engineer, went through high-resolution images of Isidis Planitia taken by NASA's Mars Reconnaissance Orbiter and spotted a bright object in roughly the right place. The HiRISE team confirmed it, with the rear cover and parachute lying nearby. Beagle 2 had survived entry, descent and landing intact. It was sitting on the ground with at most three of its four solar panels open — and all four had to open before the radio antenna underneath them was exposed.

It landed. It simply could not say so. That is the era's lesson in miniature: reaching the surface intact is only most of the problem.