On 07/22/2014 08:41 AM, Dave Marthouse wrote: > A digital satellite would imply loads of processing power on the > satellite. I would assume that with this additional activity that there > will be more > hardware on the bird with more complexity as this won't be a bent pipe > system.
Not necessarily. Yes, it will rely on onboard computers -- but so do the many analog satellites that use them for command and control. When the IHU memory on AO-10 failed after 3 years in a high radiation orbit, the analog transponder continued to operate but there was no way to repoint the antennas and solar panels or to change the operating mode or power system setpoints. > With more physical hardware of much more complexity in orbit what about > the radiation hazards to this more complex and physical hardware heavier > system? Wouldn't a software based system be prone to radiation induced > hardware and software glitches? > What about shielding etc? Radiation usually isn't a serious problem in LEO, though relatively simple precautions like error-corrected memory are still a good idea. With 14-16 day-night cycles per day, the usual problem is battery wearout. And for low altitude cubesats, atmospheric drag usually trumps everything else. Small objects tend to have small ballistic coefficients making them more susceptible to drag. Even ARISSat-1, which was larger and heavier than a cubesat, decayed in only a few months. Most cubesat launch opportunities are to low altitudes, partly because that's where the ISS flies, and partly because of the increasing pressure to minimize space debris by keeping them out of the longer-lived altitudes. _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
