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It appears to be largely political issues that prevented this mission from using a Radioisotope thermoelectric generator , which would have eliminated this part

It appears to be largely political issues that prevented this mission from using a Radioisotope thermoelectric generator , which would have eliminated this particular problem since solar panels would not be required. [1] This is how the Curiosity rover is powered. If that is the case it's a massive shame - irrational fear of nuclear technology does a lot of damage. 1 - http://www.space4peace.org/ianus/npsm2.htm#2_3 http://www.space4peace.org/ianus/npsm2.htm#2_3

acqq 12y ago
The first (failed) mission to Mars was attempted as early as 1960 by the USSR, continuing with 1964, 1965 Mariner by the US. Rovers came after a lot of previous work done, including a lot of unsuccessful attempts. And the rover weights 900 kg, probably 40 kg of it is the nuclear power generator. Philae is only 100 kg and the first on the comet. It's certainly not "fear" of the nuclear technology in Europe that prevented something. See for example: http://en.m.wikipedia.org/wiki/Nuclear_power_in_France http://en.m.wikipedia.org/wiki/Nuclear_power_in_France It's that the engineering tradeoffs have to be considered.
- guscost 12y ago
  While it seems perhaps uncharacteristic of a space agency to make engineering decisions based on politics, if I had to guess I'd imagine that the team was well aware of the PR effect of the power supply chosen for their lander. I would also guess that the same issue was considered at NASA while planning the Mars Exploration Rover (solar) and Curiosity (RTG) missions. Are you claiming that this did not factor into their decision at all?
  - NeverEnough 12y ago
    that it wasn't a significant factor, at least
    - guscost 12y ago
      Fair enough. I don't know nearly enough about Europe or the ESA to volunteer an over/under on that.
  - acqq 12y ago
    Space exploration was always very dependent on politics. As Neil deGrasse Tyson says, NASA was founded on the fear factor of USSR's Sputnik which was launched using the intercontinental ballistic missile technology. BTW: According to the comments here, the solar power generation on Philae weights at least 20 times less than the nuclear generator would.
    - guscost 12y ago
      Any hypothetical RTG for this mission would almost certainly weigh less than the one on the Curiosity rover. This lander does not need 100+ watts of power for 10 years. Consider that the RTG from the Pioneer 10 mission weighed less than 16kg: http://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_Power#SNAP-19 http://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_P...
      - acqq 12y ago
        Thanks. That still makes some 10 times less weight for solar panels. Still, once US makes a mission, I can imagine they would consider using that, launching much heavier probe etc. This was an European mission, not having access to the US resources.
        guscost 12y ago
        Wow, I just looked into it and it turns out the ESA actually hasn't used RTGs before, but planned to use one with this very mission[0:p78]. The only ESA mission I can find which used an RTG is the Cassini-Huygens probe[1], a collaboration with NASA. [0] http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspapiere/5-1998.pdf http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspap... [1] http://en.wikipedia.org/wiki/Cassini–Huygens http://en.wikipedia.org/wiki/Cassini–Huygens
        acqq 12y ago
        Where do you see that ESA actually planned to use a RTG for Rosetta mission? On the p78 is only "The consortium formed of leading institutes of Europe includes the scientific organisations of Germany, Finland, Italy, Hungary, Great Britain and Austria, which have not the technological capacity to manufacture RTGs. It was therefore decided to develop new high-efficiency solar cell for this deep space mission."
  - this_user 12y ago
    It seems highly unlikely that any scientists would make subpar choices that may compromise a long-term project on the off chance that it might cause some political discomfort. The latter isn't even particularly likely since there is a large difference between nuclear power as an energy source on Earth and nuclear technology for scientific use in space. In addition most of the public doesn't even know or is interested in the technical details of a mission like this. Therefore it is extremely unlikely that using RTG technology would have caused any kind of political problems which makes avoiding said technology on political grounds simply nonsensical when it has the potential to compromise the overall mission.
    - guscost 12y ago
      I think you are 1) overestimating the amount of independence that a typical space agency project actually enjoys and 2) underestimating both the amount and variety of PR that a high-profile space mission like this one generates.
    - TeMPOraL 12y ago
      The issue is that Europe never developed RTG technology because of politics, so scientists couldn't even consider it as an available choice.
toddmatthews 12y ago
pound for pound, solar power is much cheaper. you cant disregard the weight considerations of a thermoelectric generator
- danielweber 12y ago
  Yes. I love nuclear, and think we should use a lot more of it both on earth and in space. But for things in the inner solar system not landing on a planet, solar is often the right answer.
fbender 12y ago
(Aerospace engineer/student here) While there were certainly some political aspects to the question, there were other more pressing reasons to not pursue an RTG design. First and foremost (as others have pointed out) is the lack of knowledge towards this technology within the EU/ESA member states. Also, there's little left of the fuel usually used for these generators (238-PuO2 in space applications), and while it can be bred, none was produced for centuries (last time I checked). It is expected that NASA can only launch a couple of addtional RTG-powered missions before its ressources are depleted. An RTG also poses quite a few engineering challenges for the spacecraft itself. They are huge and heavy with low efficiency, and their design requires them to be positioned on the outside with sufficient surface area to radiate away their heat. One of their main benefits – almost constant power for a long time – is also their biggest flaw: Their power output cannot be regulated. While these challenges are in no way unsolvable (they are used both in space and on Earth), they require a certain spacecraft design which makes them unsuitable for many missions. If you take a look at the design of Philae and where it was attached to Rosetta, there is no way an RTG would have fit the design and mission characteristics chosen. They could have chosen a different design. Though the question is then: Would this have changed anything wrt science output and/or success of the mission? I personally don't think so: An RTG would have increased cost and complexity without a significant impact on science output. An RTG would not have helped with the harpoon and ADS (cold gas thruster) issues which are the primary reasons why Philae landed in the shadows. Though certainly a malfunction has happened, I do not consider this mission a failure, quite the opposite is true! Due to the hopping, there's a slew of unexpected science data which awaits to be analyzed. Additionally, there's still the chance that Philae may regain enough power once the comet is closer to the sun. Lastly, the primary mission objective – analyzing a comet – is still well underway with Rosetta orbitting Tschurie.
- crawshaw 12y ago
  Happily, Pu-238 is being manufactured again: http://news.discovery.com/space/nasa-plutonium-production-space-fuel-130314.htm http://news.discovery.com/space/nasa-plutonium-production-sp... Another source I read at the time of the announcement said it will take a while to spin up, so there are some mission constraints over the next ten years. A Europa mission would wipe out existing supplies.

acqq 12y ago

The first (failed) mission to Mars was attempted as early as 1960 by the USSR, continuing with 1964, 1965 Mariner by the US. Rovers came after a lot of previous work done, including a lot of unsuccessful attempts. And the rover weights 900 kg, probably 40 kg of it is the nuclear power generator. Philae is only 100 kg and the first on the comet. It's certainly not "fear" of the nuclear technology in Europe that prevented something. See for example: http://en.m.wikipedia.org/wiki/Nuclear_power_in_France http://en.m.wikipedia.org/wiki/Nuclear_power_in_France It's that the engineering tradeoffs have to be considered.

guscost 12y ago
While it seems perhaps uncharacteristic of a space agency to make engineering decisions based on politics, if I had to guess I'd imagine that the team was well aware of the PR effect of the power supply chosen for their lander. I would also guess that the same issue was considered at NASA while planning the Mars Exploration Rover (solar) and Curiosity (RTG) missions. Are you claiming that this did not factor into their decision at all?
- NeverEnough 12y ago
  that it wasn't a significant factor, at least
  - guscost 12y ago
    Fair enough. I don't know nearly enough about Europe or the ESA to volunteer an over/under on that.
- acqq 12y ago
  Space exploration was always very dependent on politics. As Neil deGrasse Tyson says, NASA was founded on the fear factor of USSR's Sputnik which was launched using the intercontinental ballistic missile technology. BTW: According to the comments here, the solar power generation on Philae weights at least 20 times less than the nuclear generator would.
  - guscost 12y ago
    Any hypothetical RTG for this mission would almost certainly weigh less than the one on the Curiosity rover. This lander does not need 100+ watts of power for 10 years. Consider that the RTG from the Pioneer 10 mission weighed less than 16kg: http://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_Power#SNAP-19 http://en.wikipedia.org/wiki/Systems_for_Nuclear_Auxiliary_P...
    - acqq 12y ago
      Thanks. That still makes some 10 times less weight for solar panels. Still, once US makes a mission, I can imagine they would consider using that, launching much heavier probe etc. This was an European mission, not having access to the US resources.
      - guscost 12y ago
        Wow, I just looked into it and it turns out the ESA actually hasn't used RTGs before, but planned to use one with this very mission[0:p78]. The only ESA mission I can find which used an RTG is the Cassini-Huygens probe[1], a collaboration with NASA. [0] http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspapiere/5-1998.pdf http://www.ianus.tu-darmstadt.de/media/ianus/pdfs/arbeitspap... [1] http://en.wikipedia.org/wiki/Cassini–Huygens http://en.wikipedia.org/wiki/Cassini–Huygens
        acqq 12y ago
        Where do you see that ESA actually planned to use a RTG for Rosetta mission? On the p78 is only "The consortium formed of leading institutes of Europe includes the scientific organisations of Germany, Finland, Italy, Hungary, Great Britain and Austria, which have not the technological capacity to manufacture RTGs. It was therefore decided to develop new high-efficiency solar cell for this deep space mission."
- this_user 12y ago
  It seems highly unlikely that any scientists would make subpar choices that may compromise a long-term project on the off chance that it might cause some political discomfort. The latter isn't even particularly likely since there is a large difference between nuclear power as an energy source on Earth and nuclear technology for scientific use in space. In addition most of the public doesn't even know or is interested in the technical details of a mission like this. Therefore it is extremely unlikely that using RTG technology would have caused any kind of political problems which makes avoiding said technology on political grounds simply nonsensical when it has the potential to compromise the overall mission.
  - guscost 12y ago
    I think you are 1) overestimating the amount of independence that a typical space agency project actually enjoys and 2) underestimating both the amount and variety of PR that a high-profile space mission like this one generates.
  - TeMPOraL 12y ago
    The issue is that Europe never developed RTG technology because of politics, so scientists couldn't even consider it as an available choice.

toddmatthews 12y ago

pound for pound, solar power is much cheaper. you cant disregard the weight considerations of a thermoelectric generator

danielweber 12y ago
Yes. I love nuclear, and think we should use a lot more of it both on earth and in space. But for things in the inner solar system not landing on a planet, solar is often the right answer.

fbender 12y ago

(Aerospace engineer/student here) While there were certainly some political aspects to the question, there were other more pressing reasons to not pursue an RTG design. First and foremost (as others have pointed out) is the lack of knowledge towards this technology within the EU/ESA member states. Also, there's little left of the fuel usually used for these generators (238-PuO2 in space applications), and while it can be bred, none was produced for centuries (last time I checked). It is expected that NASA can only launch a couple of addtional RTG-powered missions before its ressources are depleted. An RTG also poses quite a few engineering challenges for the spacecraft itself. They are huge and heavy with low efficiency, and their design requires them to be positioned on the outside with sufficient surface area to radiate away their heat. One of their main benefits – almost constant power for a long time – is also their biggest flaw: Their power output cannot be regulated. While these challenges are in no way unsolvable (they are used both in space and on Earth), they require a certain spacecraft design which makes them unsuitable for many missions. If you take a look at the design of Philae and where it was attached to Rosetta, there is no way an RTG would have fit the design and mission characteristics chosen. They could have chosen a different design. Though the question is then: Would this have changed anything wrt science output and/or success of the mission? I personally don't think so: An RTG would have increased cost and complexity without a significant impact on science output. An RTG would not have helped with the harpoon and ADS (cold gas thruster) issues which are the primary reasons why Philae landed in the shadows. Though certainly a malfunction has happened, I do not consider this mission a failure, quite the opposite is true! Due to the hopping, there's a slew of unexpected science data which awaits to be analyzed. Additionally, there's still the chance that Philae may regain enough power once the comet is closer to the sun. Lastly, the primary mission objective – analyzing a comet – is still well underway with Rosetta orbitting Tschurie.

crawshaw 12y ago
Happily, Pu-238 is being manufactured again: http://news.discovery.com/space/nasa-plutonium-production-space-fuel-130314.htm http://news.discovery.com/space/nasa-plutonium-production-sp... Another source I read at the time of the announcement said it will take a while to spin up, so there are some mission constraints over the next ten years. A Europa mission would wipe out existing supplies.