5 ms·

See this discussion and article from earlier today: http://news.ycombinator.com/item?id=4360502 http://news.ycombinator.com/item?id=4360502

by sunsu 14y ago

EternalFury 14y ago
Thanks! The reason seems to be: It's the way it was planned 10 years ago and we don't go back on planning on a project like this one.
- noonespecial 14y ago
  Its more than just choosing the camera 10 years ago, its having 10 years of testing of that particular camera under their belt and knowing every in and out of it. 10 years is plenty of time for any quirky behavior to emerge and be dealt with.
- jser 14y ago
  Several articles have mentioned bandwidth limitations of about 250 megabits per day, which also has to be used to send instrument data. But I haven't seen an explanation why bandwidth is so low -- is it lack of spectrum? Interference issues?
  - elithrar 14y ago
    > But I haven't seen an explanation why bandwidth is so low -- is it lack of spectrum? Interference issues? Transmit power.
    - utoku 14y ago
      According to wikipedia article, the power source is designed to create 125 watts of electrical power from 2000 watts of thermal power. (It might look inefficient, but they are using the heat in all parts of the rover.) For comparison, that might be how much your graphics card might be consuming while you are reading this article. I guess that also means it is going to move very slow.
  - uvdiv 14y ago
    The bandwidth to the orbiters is up to 2 Mbps, but because they're in low orbit they're only in sight 8 minutes per day. http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/data/ http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/...
    - utoku 14y ago
      A bit of clarification, I think the orbiters are in sight of Earth for most of the day. It is Curiosity that is not in sight of the Orbiters, again because of their low orbit.
      - danielweber 14y ago
        I'm not sure I understand. Gale Crater is pretty near the equator, so any equatorial satellite would pass quickly over it, but many many times per day.
        uvdiv 14y ago
        You answered your own question: both satellites are in polar orbits. They pass the equator many times a day, but at a different longitude each time.
    - hereonbusiness 14y ago
      I think it may be time to put a dedicated communications satellite around Mars. These rovers do seem to last a long time so it probably would be worth it.
      - ZoFreX 14y ago
        We would need at least three for constant contact, Arthur C. Clarke style.
      - wlievens 14y ago
        There is, that's the role MSO is performing, no? What you'd need is a whole series of them to increase coverage.
  - deleted 14y ago
    [deleted]
- rhizome 14y ago
  It's not like they have extra batteries and they just add a power strip for the better camera. The change you suggest would involve re-engineering, which would increase your lamented cost of this mission.
- yaix 14y ago
  Maybe Instagramm built the camera? But seriously, I guess for the same reason Couriosity runs on old PowerPC processors. They are just well tested and less likely to fail. If you want a high res image, you can always take 10 images and glue them together, result is the same.
  - neilmiddleton 14y ago
    Not quite - it's still the same res, but bigger.
- jeza 14y ago
  This topic was also discussed here (regarding some previous missions): http://news.ycombinator.com/item?id=4356878 http://news.ycombinator.com/item?id=4356878 They use a black and white CMOS to accurately measure the actual light hitting the lens (which may include non visible spectrum. To get a colour image they need to use filters and take multiple photos, where as consumer cameras have a fixed grid (Bayer pattern) of one filter per each pixel. That probably won't give you such an accurate picture. Also when they're using filters they're not interested in reproducing true colour but rather highlighting a difference in materials. The bandwidth constraints no doubt the reason they didn't change the sensor. Besides, when they combine three different images taken with filters to create one colour image it will essentially be 6MP anyway.
- mattstreet 14y ago
  More like A) We aren't getting the pictures from the best cameras yet and B) We didn't send the latest, greatest best cameras because we didn't want them to fail after 10 minutes use. We send up camera's tested and hardened against temperature changes, dust, vibration, and radiation. Also cameras that require low power. Furthermore, there is limited bandwidth. So we probably want to send back mediocre pictures most of the time and if we see something we really want in high quality we take a bunch of pictures of it and put them together. As a final note, the quality of the sensor and lens probably matters a lot more than the number of mega pixels.

See this discussion and article from earlier today: http://news.ycombinator.com/item?id=4360502 http://news.ycombinator.com/item?id=4360502

by sunsu 14y ago

See this discussion and article from earlier today: http://news.ycombinator.com/item?id=4360502 http://news.ycombinator.com/item?id=4360502

EternalFury 14y ago

Thanks! The reason seems to be: It's the way it was planned 10 years ago and we don't go back on planning on a project like this one.

noonespecial 14y ago
Its more than just choosing the camera 10 years ago, its having 10 years of testing of that particular camera under their belt and knowing every in and out of it. 10 years is plenty of time for any quirky behavior to emerge and be dealt with.
jser 14y ago
Several articles have mentioned bandwidth limitations of about 250 megabits per day, which also has to be used to send instrument data. But I haven't seen an explanation why bandwidth is so low -- is it lack of spectrum? Interference issues?
- elithrar 14y ago
  > But I haven't seen an explanation why bandwidth is so low -- is it lack of spectrum? Interference issues? Transmit power.
  - utoku 14y ago
    According to wikipedia article, the power source is designed to create 125 watts of electrical power from 2000 watts of thermal power. (It might look inefficient, but they are using the heat in all parts of the rover.) For comparison, that might be how much your graphics card might be consuming while you are reading this article. I guess that also means it is going to move very slow.
- uvdiv 14y ago
  The bandwidth to the orbiters is up to 2 Mbps, but because they're in low orbit they're only in sight 8 minutes per day. http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/data/ http://mars.jpl.nasa.gov/msl/mission/communicationwithearth/...
  - utoku 14y ago
    A bit of clarification, I think the orbiters are in sight of Earth for most of the day. It is Curiosity that is not in sight of the Orbiters, again because of their low orbit.
    - danielweber 14y ago
      I'm not sure I understand. Gale Crater is pretty near the equator, so any equatorial satellite would pass quickly over it, but many many times per day.
      - uvdiv 14y ago
        You answered your own question: both satellites are in polar orbits. They pass the equator many times a day, but at a different longitude each time.
  - hereonbusiness 14y ago
    I think it may be time to put a dedicated communications satellite around Mars. These rovers do seem to last a long time so it probably would be worth it.
    - ZoFreX 14y ago
      We would need at least three for constant contact, Arthur C. Clarke style.
    - wlievens 14y ago
      There is, that's the role MSO is performing, no? What you'd need is a whole series of them to increase coverage.
- deleted 14y ago
  [deleted]
rhizome 14y ago
It's not like they have extra batteries and they just add a power strip for the better camera. The change you suggest would involve re-engineering, which would increase your lamented cost of this mission.
yaix 14y ago
Maybe Instagramm built the camera? But seriously, I guess for the same reason Couriosity runs on old PowerPC processors. They are just well tested and less likely to fail. If you want a high res image, you can always take 10 images and glue them together, result is the same.
- neilmiddleton 14y ago
  Not quite - it's still the same res, but bigger.
jeza 14y ago
This topic was also discussed here (regarding some previous missions): http://news.ycombinator.com/item?id=4356878 http://news.ycombinator.com/item?id=4356878 They use a black and white CMOS to accurately measure the actual light hitting the lens (which may include non visible spectrum. To get a colour image they need to use filters and take multiple photos, where as consumer cameras have a fixed grid (Bayer pattern) of one filter per each pixel. That probably won't give you such an accurate picture. Also when they're using filters they're not interested in reproducing true colour but rather highlighting a difference in materials. The bandwidth constraints no doubt the reason they didn't change the sensor. Besides, when they combine three different images taken with filters to create one colour image it will essentially be 6MP anyway.
mattstreet 14y ago
More like A) We aren't getting the pictures from the best cameras yet and B) We didn't send the latest, greatest best cameras because we didn't want them to fail after 10 minutes use. We send up camera's tested and hardened against temperature changes, dust, vibration, and radiation. Also cameras that require low power. Furthermore, there is limited bandwidth. So we probably want to send back mediocre pictures most of the time and if we see something we really want in high quality we take a bunch of pictures of it and put them together. As a final note, the quality of the sensor and lens probably matters a lot more than the number of mega pixels.