Traveling across the solar system, the New Horizons spacecraft is now approximately 3.5 billion miles from the Sun, nine years after its launch.

New Horizons is a spacecraft sent by NASA to study Pluto

The probe carries American astronomer Clyde Tombaugh‘s ashes (he discovered Pluto in 1930) and has been navigating the solar system using two computer systems: one is used for command and data handling while the other handles guidance and control. For safety reasons, each of the two systems is duplicated, leading to a total of four on-board processors.

One small step for technology, one giant leap for CPUs

The CPU of choice for New Horizons is a MIPS-based Mongoose-V chip clocked at a whopping 12 MHz. Mongoose-V is a radiation-hardened version of the MIPS R3000 CPU and is manufactured by Synova, a Florida-based company that specializes in turnkey aeronautics solutions.

Mongoose-V is a MIPS-based processor designed by Synova

The engineers at NASA and Synova have worked together to implement multiple clocks and timing routines in hardware and software to help prevent faults and downtime. The Mongoose-V processor analyzes positional information, distributes operating commands to multiple spacecraft subsystems, collects and processes instrument data, and sends bursts of data back to Earth. It also runs an advanced autonomy algorithm that allows the probe to auto-correct any issues or contact operators on Earth for help (more information here).

A history of the MIPS R3000 processor

MIPS R3000 is a 32-bit RISC microprocessor chip found in workstations and servers designed by companies such as Evans & Sutherland, DEC, Silicon Graphics, Tandem Computers, Whitechapel Workstations and many others; most notably, it was the CPU of choice for the original PlayStation game console from Sony and is still being used by Toshiba in a range of microcontrollers. It is a second-generation implementation of the MIPS I ISA and was introduced in the late 1980s, following the success of the flagship R2000 microprocessor.

Since the MIPS instruction set is known for its elegant simplicity, MIPS R3000 is significantly smaller in size compared to similar CPU architectures launched around that time (80×86, 680×0 etc.). The reduced instruction set combined with a 5-stage pipeline design allows R3000 to execute most instructions at a rate close to 1 instruction per cycle.

In addition to the CPU core, the R3000 microprocessor includes an external R3010 FPU (essentially a numeric coprocessor), a memory controller and other on-chip peripherals (error detection and correction, timer, dual UART, expansion interrupts); you can find a block diagram of the design below:

A block diagram of the Mongoose-V chip

There is also a PDF describing the processor’s architecture here; for those wondering if DAWG was Synova’s attempt at 1980s gangsta rap, it is actually short for Dynamic Automatic Waitstate Generator.

Where will MIPS go next?

The New Horizons probe is the first mission in NASA’s New Frontiers Program. Once a NASA mission completes its prime objective, the agency forms a committee to determine whether extended operations are warranted or if the spacecraft can return to Earth.

Now that the New Horizons spacecraft has arrived to Pluto, it will explore the planet and its moons. The New Frontiers team will then submit a proposal to NASA in late 2016 for an extended mission to fly by one or two other Kuiper belt objects that were recently uncovered by the Hubble Space Telescope.

To keep up to date with the New Frontiers Program, follow NASA on Twitter at @NewHorizons2015. For the latest news and announcements from MIPS, make sure you check out our social media channels too (@ImaginationPR, @MIPSGuru, @MIPSdev).