Half successes
In 2003, the European Space Agency successfully piloted Mars Express into orbit around the Red Planet. In December of that year, the orbiter released its lander component,
Beagle 2, for a Christmas Day touchdown. The lander went out of radio contact, and was never heard from again. Scientists assumed the lander had crashed, though they hadn’t received any sign of malfunction.
Then, in 2016, researchers looking over martian satellite photography found the crash site — which wasn’t a crash at all. It turned out the lander had settled, to all appearances, quite gently onto the martian terrain. Its deployed parachute is even visible in some imagery. The problem was its solar arrays, one of which didn’t unfold correctly, leaving the lander unable to send signals back to Earth. Beagle 2 was ultimately tantalizingly close to success, while still completely failing its mission objective.
ESA’s bad luck continued. In 2016, they again succeeded in getting a spacecraft into orbit — this time the Trace Gas Orbiter. Again it released a lander, Schiaparelli. This time, the landing module kept in constant contact with its orbiting partner so that scientists would have a better record of the craft’s descent. This meant they were fully informed when the lander slammed into the Red Planet at 340 mph.
Schiaparelli’s sensors overloaded during a turbulent descent, causing the spacecraft to think it was underground when it was actually still a few miles in the air. In sort-of-rational response, the craft ejected its parachute and only fired its landing thrusters for a few seconds, assuming it was at ground level. It was not. The lander plummeted the rest of the way to the ground. But hey, at least this time engineers knew what had happened.