WASHINGTON – The Curiosity rover now gearing up to explore a 96-mile-wide crater on Mars is by far the most complex machine ever to explore the surface of another planet. One big reason is the rover’s avionics, which control everything from its 10 scientific instruments to communications, navigation, cameras and power management – which is where Curiosity’s “dream mode” enters the picture.
Dream mode “is sort of the reptile brain for the rover,” explained Jim Donaldson, the Mars Science Laboratory avionics chief engineer. Implemented in FPGAs, the rover’s dream mode function monitors vital rover systems while its redundant main computers are in “sleep mode” to save power.
Donaldson said the biggest challenge engineers at NASA’s Jet Propulsion Laboratory (JPL) faced in developing rover avionics was development and implementation of the FPGAs that have provided Curiosity with a quantum leap in functionality as it explores the Red Planet. From an engineering standpoint, Donaldson said the biggest challenge was scaling JPL’s FPGA design practices to achieve the higher levels of complexity needed to put a largely autonomous rover inside Gale Crater, which is believed to harbor the conditions needed for microbial life.
JPL and its contractors eventually came up with a system of redundant avionics hardware implemented on about 1.2 million logic gates. That allows the rover’s avionics to interface with all major scientific instruments, sensors and comms links along with the rover’s drive train while also managing power in wake, sleep and dream modes.
Part of the Curiosity's power supply is visible at left. To the right of the power supply is the low-gain antenna and side of the paddle-shaped high-gain antenna for communications directly to Earth. The rim of Gale Crater is the lighter colored band across the horizon. (Source: NASA/JPL-Caltech)