3 ms·

It's also a mostly obsolete problem now as current rovers use RTGs instead.

dr_zoidberg 8y ago
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 I wouldn't say solar power is obsolete for Mars rovers/landers.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
cstross 8y ago
For technical reasons deep space missions usually run on Plutonium 238 RTGs. Pu-238 is scarce: "In 1992, the US arranged to buy 30 kg of Pu-238 from Russia for US$6M ($200K/kg). Even counting the effects of inflation, this was a real bargain, although in the end only about 20 kg was delivered." (Source: https://newatlas.com/nasa-cancels-advanced-sterling-radioisotope-generator/29880/ https://newatlas.com/nasa-cancels-advanced-sterling-radioiso...). More recent proposals to restart US Pu-238 production using a dedicated reactor suggest a probable price of $10-15M/Kg, meaning that a single RTG for one deep space mission will require on the order of $100M of fuel and soak up 4-8 years national production. A further ramp-up of Pu-238 manufacturing is not inconceivable, but with PV cells that can operate usefully in Jupiter orbit, we only need Pu-238 for outer planet missions and some specialized purposes (e.g. a Mercury lander that spends a lot of time in complete darkness, or a truck-sized Mars rover).
- monocasa 8y ago
  It's too bad that France's fast breeder reactors were shut down due to political pressure. They made Pu-238, among other isotopes.

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

cstross 8y ago

For technical reasons deep space missions usually run on Plutonium 238 RTGs. Pu-238 is scarce: "In 1992, the US arranged to buy 30 kg of Pu-238 from Russia for US$6M ($200K/kg). Even counting the effects of inflation, this was a real bargain, although in the end only about 20 kg was delivered." (Source: https://newatlas.com/nasa-cancels-advanced-sterling-radioisotope-generator/29880/ https://newatlas.com/nasa-cancels-advanced-sterling-radioiso...). More recent proposals to restart US Pu-238 production using a dedicated reactor suggest a probable price of $10-15M/Kg, meaning that a single RTG for one deep space mission will require on the order of $100M of fuel and soak up 4-8 years national production. A further ramp-up of Pu-238 manufacturing is not inconceivable, but with PV cells that can operate usefully in Jupiter orbit, we only need Pu-238 for outer planet missions and some specialized purposes (e.g. a Mercury lander that spends a lot of time in complete darkness, or a truck-sized Mars rover).

monocasa 8y ago
It's too bad that France's fast breeder reactors were shut down due to political pressure. They made Pu-238, among other isotopes.