The Perseverance rover on Mars has a 20-year-old processor. Reported by New Scientist.
The rover is based on the PowerPC 750 chip. This is the 700 series processor launched in the late 1990s. Manufactured using the 250 process technology, the device has one core, about one million transistors, and a frequency of 233 megahertz. The PowerPC 750 is paired with the iMac G3, released by Apple in November 1997.
Looks like space missions do not require a lot of power?
AFAIK most power is used to keep the rover or space craft from freezing to death.
Equipment for space missions must above all be robust and resistant to cosmic radiation. Radiation leads to soft errors already in the earth’s atmosphere.
Yes, I know about it. And I perfectly understand that this chip was specially prepared for Martian conditions. However, it is surprising that the rover needs less than a text editor.
It can take up to 20 minutes to receive any message sent from the rover, and probably much more depending on how much data is being sent, so that also changes the balance of how much computational power it really needs.
This is just a WAG, but I’m thinking without the need for autonomous operation Perseverance could have probably got by with even less computational power than it has.
The silicon stuff space folk get to use, are working with mindset of lower power demands and sustenance [parade of long term research engagements, and of course, coping to the elements]
My understanding is its not about the power its about the known risk of failure. When your sending something worth billions of $$$ you need to be really really confident that everything in it will work when it arrives. So NASA uses electronics that have long service histories and known failure rates so they can statistically estimate the risk of sending a particular chip. They also select for things that are hardened vs radiation. Often these system use a dual processor system that does the calculations in parallel and then checks the two results. That way if a stray cosmic ray flips a bit we know that something went wrong and can calculate it again.
This is also why a lot of military tech uses what we consider “outdated” components as well, because they are more resistant to EMP’s and now directed microwave weapons that can disrupt or even fry electrical components over an area.
Everything was explained in a recent episode of the Linux Unplugged podcast with Tim Canham. There’s more to it than being radiation resilient. It’s a good listen-
The processor is more than capable of advanced computation. The hardware may not be cutting edge silicon but with sensible software optimization it will run just fine.
Besides they had to use non hyperthreaded CPUs because of the threat of a side channel attack from Marvin the Martian.
No actually it’s aRAD750, a 400 mhz sec solution built on the 750 G3. While architecturally the same, the RAD is hardened against radiation, operates at super low temps, and hose some extra altivec accelerator ‘cores’.
No they used that chip because the govt literally refused to let them look at anything else, then they tried to shut the programs down for like 8-12 years.
IIRC, the PowerPC chips is used for the core functions because it’s been proven so resilient over the last 20 years of missions. There’s a much more powerful x86 machine in it to handle media encoding and such, where a flipped bit isn’t the absolute end of the world.
three things:
This is most apparent with image sensors sent up to space. Cosmic rays destroy pixels over time and you get TONS of dead pixels with HD sensors and up. The recent HD camera used for a ISS spacewalk had like 600-1000 dead pixels.
Thank you for your responses. So a minimal processor might be enough for a payload control system for a small suborbital rocket like SkyHy? The main thing is that it is protected from cosmic radiation?
The Earth’s magnetosphere is about the only thing that keeps our civilization alive.
When you get outside of it, you need serious shielding because its like being shot with gamma rays from all directions constantly.
Its why if we want to go to mars/live on mars we have to cure cancer first.
Look up the spec on the Apollo guidance computer.
I think you massively underestimate the processor.
I’ve run text editors on the amiga, c64, 8088 dos pc etc.