I might add a couple of things.

The 1990 AMSAT NA microsats ran on NEC V40's, essentially an 80286, at
2.5MHz clock speed. They nicely handled 4 simultaneous uplinks and one
downlink at 1200 bps, along with store and forward messages and
telemetry collection and downlink.  Later we we used that same processor
board design in Falconsat-3 for the Air Force Academy which ran for the
AFA, then in amateur use for 16 years. It had the same store and forward
messaging, plus several experiments on board.  And, all of those
satellites had 256k of memory.

Some years ago we built a couple of cubesats that ran on an AtMega64 8
bit processor with a 11Mhz clock speed.  We used only it's internal RAM
for processing storage, but had a 16Mb RAM chip for storing experiment data.

In the past few years the universities I work with who are building
cubesats tend to use Arduino, Beagle Bone Black, or Raspberry Pi, as the
main processor.  Or they buy processor boards from suppliers of cubesat
subsystems - which are also pretty fast.  The processing capability is
way overkill for the mission needs but that's what is available off the
shelf and it's what the students tend to be familiar with. So those are
good choices. These more capable processors are enabled by the doubling
of solar panel efficiency in the past 10 years or so, in some cases
including fold out solar panels, and by improvements in battery technology.

Jim, WD0E

Colorado Satellite Services



On 1/31/2024 5:49 PM, Joseph B. Fitzgerald via AMSAT-BB wrote:
> Sasha Tim wrote:
>
>> This entire satellite runs on an Atmega328...
> You can do a lot with just a little, the Atmaga 328 compares favorably to the computers that took US astronauts to the moon in many ways. Roughly the same memory and computing power, plus the '328 consumes orders of magnitude less space, power, weight and dollars.  Saturn and Apollo computers likely were better in radiation resistance and reliability though.
>
> AMSAT used radiation hardened RCA COSMAC 1802 on several spacecraft, and I think one is still running on UO-11. That thing ran very slow, with a machine cycle of about 100 kHz, with opcodes taking 2 or 3 cycles to complete.
>
> de KM1P Joe
>
>
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