Could they not offload a lot of compute to ground based computers and submit results back via radio? Or are these real-time applications?
There must be some equation of motion in space robots that combines terrain difficulty, robot speed, round trip time to Earth, and how far ahead you’d need to be able to see.
Curiosity moves about as fast as a Roomba. The ping is (min/avg/max) 10’/24’/40’. Ergo, it needs to be able to see X yards ahead of itself to plan A* from Earth, requiring a camera boom Y feet tall producing images with Z megapixels of resolution.
I wonder what X, Y and Z are.
- You want a travel speed of 0.5 m/s - Worst-case round trip time from command to result is 40 minutes, or 2400 seconds - Max distance covered is 1200 meters - Assume you can drive over any rock 10cm or less in size (the rover can do better, but at a reduced speed)
So you need to scan an area 1200m x 1200m, with range accuracy of, say, +/-5cm. Forget the camera boom height, or the time it might take to scan and process, there's no sensor that will give you that kind of accuracy. The stereo baseline would be huge, and leave you entirely at the mercy of whatever texture or not a given part of the martian surface has to offer. LIDAR is OK if you definition of "long range sensing" is larger objects at 200m. The time cost for shipping back all the raw data for processing would kill performance as well, and if you wanted to process it locally the compute requirements would be just as high as doing the planning locally as well.
Onboard, or at least much closer,compute is the only way forward in autonomy. Honestly, the best bet on improving local compute would be to send a robot bulldozer, some C4, a rack full of milspec servers, and a big RTG. Blow a nice crater, push the servers to the bottom, and bury them in dirt for shielding. If you get really lucky, you could find some old cave or lava tube.
One drawback of the remote A* approach is that you end up using more energy as the rover would have to be constantly communicating with its onboard antenna. Its relay satellites are only in range for a limited period each day. Fine grained maneuvers (like drive around that big rock to get to this small rock) would also prove difficult because of likely errors in the rover's inertial-navigation system.
Some quick googling says-
Curiosity max speed equals 0.08699 mph.
Roomba equals a foot per second which is 0.682 mph.
Off by about 7.82x.
I remember once hearing that Curiosity, flat out, could do 1km a day.
Also it seems to be doing sometype of image processing to identify a suitable landing spot and guiding on to that point.
So practically it would still experience significant radiation.
But having the main compute for Mars remain in orbit with the relay isn't a bad idea.
It works for some things, but for pathfinding it isn’t a great fit.
The other issue is bandwidth between the craft and Earth, which is quite limited.
Maybe there would be benefits to a “orbiting datacenter” around Mars carrying a bunch of rad-hardened compute? I assume NASA has considered this and decided it would be a bad idea.