RTGs are controversial[0] and there is still a slow production of Pu-238 to power them in the US[1]. Plus, Mars is close to the Sun and has access to plenty of

RTGs are controversial[0] and there is still a slow production of Pu-238 to power them in the US[1]. Plus, Mars is close to the Sun and has access to plenty of solar power, compared to other targets (any mission beyond Jupiter). The Juno spacecraft used newer, more advanced solar panels, which allowed it to be solar-powered in the orbit of Jupiter[2], and pretty much the same could be done with a martian rover[3]. I wouldn't say solar power is obsolete for Mars rovers/landers. As hit has been said before, this isn't a mission which is failing due to bad solar panel technology, this is an aging rover met with extremely harsh conditions after working 15+ years longer than it was supposed to. Not only has its panels weared down, the batteries too. If it's lost in this duststorm, it's going to be sad, but not evidence that solar power is a no-go for martian exploration. [0] see all the "what if it explodes at launch" stories from MSL/Curiosity like https://www.livescience.com/33609-curiosity-launch-plutonium-danger.html https://www.livescience.com/33609-curiosity-launch-plutonium... -- Cassini went through pretty much the same before launch [1] https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator#238Pu https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge... [2] https://en.wikipedia.org/wiki/Juno_(spacecraft)#Solar_panels https://en.wikipedia.org/wiki/Juno_(spacecraft)#Solar_panels [3] Mars 2020 didn't pursue this because they were trying to reuse as much R&D as possible from MSL/Curiosity, so it stands to reason they'd use the same power source (or an updated version of). Edit: the RTG for M2020 is a spare part from MSL -- https://en.wikipedia.org/wiki/Mars_2020#Design https://en.wikipedia.org/wiki/Mars_2020#Design