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Oh interesting: > Once the rechargeable secondary battery has been warmed by sunlight again, Philae will restart and the DLR LCC team will take their places at

Oh interesting: > Once the rechargeable secondary battery has been warmed by sunlight again, Philae will restart and the DLR LCC team will take their places at the control consoles again. This is the first I've heard that Philae can wake back up. I was under the impression that it had no solar capabilities whatsoever, and that the battery was the only power it had available.

trose 12y ago
Yeah the probe is covered in panels. The main issue is that it did not land where they intended and it is mostly in shadow. I am not a rocket scientist but... it looks like it will be getting closer to the sun as time goes on here so maybe the light it can get later will be more intense and enough to power it?
- Khao 12y ago
  The main issue I read was that even though it gets some light (something like 1 hour of light per 12 hours) the battery can't recharge when it's cold. So Philae needs light to heat up the battery and only then it can start charging it so it needs a longer exposure to sunlight or it needs to be closer to the sun so it heats up faster.
  - gerry_mander 12y ago
    I thought solar panels were more efficient when cold...
    - simias 12y ago
      Most electronics are more efficient when "cold", but when we say that we mean "cold" by our earth standards, i.e. something like 15 degrees celsius. I think I read that Philae's temperature after landing was less than -160 degrees celsius. Getting anything to work at those temperatures is hard...
- RobotCaleb 12y ago
  From the panorama they released, it's in quite a hairy spot. Mattias Malmer corrected the perspective [0] and I threw it in my JS pano viewer. [1] It helps to visualize where it's sitting. [0] http://mattias.malmer.nu/2014/11/philae-final-landing-place/ http://mattias.malmer.nu/2014/11/philae-final-landing-place/ [1] http://robotrising.org/StratoSphere/index.html?src=images/philae/Civa.jpg&type=image http://robotrising.org/StratoSphere/index.html?src=images/ph...
  - trose 12y ago
    wait, is it on it's side?
    - boombip 12y ago
      It's on a slope I believe.
dekhn 12y ago
Agreed-- I haven't seen anywhere else in the news that the probe rotated it primary panel into direct sunlight.
- codeulike 12y ago
  They rotated it slightly just before the main battery ran out. They hope it might get enough light as the 'season' on the comet changes (perhaps around christmas) but no-one knows for sure.
  - dekhn 12y ago
    Do you have a link to an article with more detail?
    - codeulike 12y ago
      The official rosetta blog has details of the movement of the panels http://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ http://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ Planetary Society blogger Emily Lakdawalla has a Tumblr that had very good coverage of what went on: http://elakdawalla.tumblr.com/ http://elakdawalla.tumblr.com/ ... details of the movement, the solar charging requirements etc
      - dekhn 12y ago
        This article says something different (more factual/less speculative) than the rosetta blog post. rosetta blog post: "mission controllers sent commands to rotate the lander's main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight." article: ". The team managed to rotate the lander during the night of 14/15 November 2014, so that the largest solar panel is now aligned towards the Sun." Ms Lakdawalla's post provided more detail, including confirmation they got feedback from the lander that its movement was successful, although it wasn't clear if they were going to actually get enough light any time soon for full operations (thanks for that hint): " They commanded the lander legs to lift the body by 4 centimeters, hopefully raising it a bit farther above the horizon, and then rotating the lander body 35 degrees to place the largest solar panel in a position where it could hopefully receive the most sunlight. Telemetry confirmed that the lander moved as it had been commanded to do. "
yason 12y ago
I've understood it has solar panels. But what would be the reason they didn't put a nuclear battery on board? That would work for years. If the direct output power of the nuclear battery was too low, it could still be used to charge the rechargeable battery until it can make the lander do work again for a few hours/days.
- skywhopper 12y ago
  Nuclear batteries are 1) heavier, 2) more expensive, 3) politically complicated.
  - Someone1234 12y ago
    Atomic batteries aren't really controversial or politically sensitive and have been used to great effect by many nations involved in space travel. There's some problem with Tritium expose if the craft exploded on launch but those haven't really stopped it usage.
    - adestefan 12y ago
      The issue is getting the plutonium.
      - virtue3 12y ago
        nasa almost used up the last bits of our reserves of it for the last mars lander. Thankfully it appears that the united states department of energy is re-visiting generating plutonium-238 for NASA: http://en.wikipedia.org/wiki/Plutonium-238#United_States_supply http://en.wikipedia.org/wiki/Plutonium-238#United_States_sup...
        protomyth 12y ago
        Yet another reason to build thorium reactors since the "waste product" is PU-238.
    - 12y ago

trose 12y ago

Yeah the probe is covered in panels. The main issue is that it did not land where they intended and it is mostly in shadow. I am not a rocket scientist but... it looks like it will be getting closer to the sun as time goes on here so maybe the light it can get later will be more intense and enough to power it?

Khao 12y ago
The main issue I read was that even though it gets some light (something like 1 hour of light per 12 hours) the battery can't recharge when it's cold. So Philae needs light to heat up the battery and only then it can start charging it so it needs a longer exposure to sunlight or it needs to be closer to the sun so it heats up faster.
- gerry_mander 12y ago
  I thought solar panels were more efficient when cold...
  - simias 12y ago
    Most electronics are more efficient when "cold", but when we say that we mean "cold" by our earth standards, i.e. something like 15 degrees celsius. I think I read that Philae's temperature after landing was less than -160 degrees celsius. Getting anything to work at those temperatures is hard...
RobotCaleb 12y ago
From the panorama they released, it's in quite a hairy spot. Mattias Malmer corrected the perspective [0] and I threw it in my JS pano viewer. [1] It helps to visualize where it's sitting. [0] http://mattias.malmer.nu/2014/11/philae-final-landing-place/ http://mattias.malmer.nu/2014/11/philae-final-landing-place/ [1] http://robotrising.org/StratoSphere/index.html?src=images/philae/Civa.jpg&type=image http://robotrising.org/StratoSphere/index.html?src=images/ph...
- trose 12y ago
  wait, is it on it's side?
  - boombip 12y ago
    It's on a slope I believe.

dekhn 12y ago

Agreed-- I haven't seen anywhere else in the news that the probe rotated it primary panel into direct sunlight.

codeulike 12y ago
They rotated it slightly just before the main battery ran out. They hope it might get enough light as the 'season' on the comet changes (perhaps around christmas) but no-one knows for sure.
- dekhn 12y ago
  Do you have a link to an article with more detail?
  - codeulike 12y ago
    The official rosetta blog has details of the movement of the panels http://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ http://blogs.esa.int/rosetta/2014/11/15/our-landers-asleep/ Planetary Society blogger Emily Lakdawalla has a Tumblr that had very good coverage of what went on: http://elakdawalla.tumblr.com/ http://elakdawalla.tumblr.com/ ... details of the movement, the solar charging requirements etc
    - dekhn 12y ago
      This article says something different (more factual/less speculative) than the rosetta blog post. rosetta blog post: "mission controllers sent commands to rotate the lander's main body, to which the solar panels are fixed. This may have exposed more panel area to sunlight." article: ". The team managed to rotate the lander during the night of 14/15 November 2014, so that the largest solar panel is now aligned towards the Sun." Ms Lakdawalla's post provided more detail, including confirmation they got feedback from the lander that its movement was successful, although it wasn't clear if they were going to actually get enough light any time soon for full operations (thanks for that hint): " They commanded the lander legs to lift the body by 4 centimeters, hopefully raising it a bit farther above the horizon, and then rotating the lander body 35 degrees to place the largest solar panel in a position where it could hopefully receive the most sunlight. Telemetry confirmed that the lander moved as it had been commanded to do. "

yason 12y ago

I've understood it has solar panels. But what would be the reason they didn't put a nuclear battery on board? That would work for years. If the direct output power of the nuclear battery was too low, it could still be used to charge the rechargeable battery until it can make the lander do work again for a few hours/days.

skywhopper 12y ago
Nuclear batteries are 1) heavier, 2) more expensive, 3) politically complicated.
- Someone1234 12y ago
  Atomic batteries aren't really controversial or politically sensitive and have been used to great effect by many nations involved in space travel. There's some problem with Tritium expose if the craft exploded on launch but those haven't really stopped it usage.
  - adestefan 12y ago
    The issue is getting the plutonium.
    - virtue3 12y ago
      nasa almost used up the last bits of our reserves of it for the last mars lander. Thankfully it appears that the united states department of energy is re-visiting generating plutonium-238 for NASA: http://en.wikipedia.org/wiki/Plutonium-238#United_States_supply http://en.wikipedia.org/wiki/Plutonium-238#United_States_sup...
      - protomyth 12y ago
        Yet another reason to build thorium reactors since the "waste product" is PU-238.
  - 12y ago