Even though vented airbags are an old idea, as with many technologies for exploring Mars, they haven’t yet been tried. And when it comes to the make-or-break landing system, spacecraft engineers don’t like to take chances. From the time the spacecraft enters the atmosphere to the moment of touchdown, a Mars landing takes just a few minutes. There’s often no redundancy in the hardware, and with TV cameras in the control room, there’s no place for mission managers to hide if things go wrong. Wish them all luck.