4 ms·

I remember reading (probably from one of his books) that Sagan's idea for a life-detecting experiment on Mars was never actually sent there (apparently this exp

I remember reading (probably from one of his books) that Sagan's idea for a life-detecting experiment on Mars was never actually sent there (apparently this experiment went instead). IIRC, it was basically to put a sample in a box and just watch it to see if anything changed at all in a way that indicates that some chemical process is happening. Here are some interesting slides I found while trying to figure out what his actual experiment idea involved: https://www.vanderbilt.edu/olli/archive/Life_On_Mars_Session_5.pdf https://www.vanderbilt.edu/olli/archive/Life_On_Mars_Session...

asdff 3y ago
Microscopy could also be a good route. Microbial life should look pretty distinct from inorganic matter, even if everything in the soil sample were dead by the time it was imaged. As far as I know, we have not sent a microscope up capable of resolving even a large mammalian cell, let alone resolve 1 micron bacteria (if these microbes are even to be similar in size as those on Earth). I suspect the vibrations during launch make it especially challenging to actually get a powerful microscope out to Mars unharmed.
- jiggawatts 3y ago
  It's very important to NASA to never send anything to Mars that could definitively rule out the presence of life or water. Something I noticed a few years ago is that NASA publishes a press release every month or so with the title "possible hint of water found on Mars". There are literally thousands of such web pages on their site:https://www.google.com/search?q=site%3Anasa.gov+"hint"+"water"+"mars" https://www.google.com/search?q=site%3Anasa.gov+"hint"+"wate... Nobody ought to be this obsessed with something, unless there's an agenda. It's like cigarette companies going on and on about how their latest product is "more healthy". What's going on is that NASA has had a lot of trouble in recent decades maintaining their funding. There's not a lot in space that excites US senators. There's no oil, no resources that can be practically mined, etc... So they have to have some sort of goal, something they have to get funding for so that they can go "look for it". Some NASA administrator picked "water on Mars". Now it has morphed into a reason for the agency to exist, which means if it was ever shown not to exist, then NASA would face a real existential risk itself. So they'll drag their feet as long as possible, sending every possible instrument they can pack into a rover, except for the one that could definitively rule out life and/or water. This is why they didn't send a microscope, and most likely won't send one on the next mission either.
  - Fatnino 3y ago
    The next mission is supposed to be sample return. I agree that mars has been over explored to the detriment of all other planets, especially the outer ones.
    - raxxorraxor 3y ago
      No planet you can land on, so that leaves the moons and pluto and the cost is much higher. Not the little extra fuel and hardware requirements, but the mission time alone... Venus is extremely dense and hot that it melts all the equipment pretty quickly, Mercury is hard to reach. Probably very hot too on the very long and sunny days and the nights are too cold. It also require the most fuel to visit without space brakes.
      - Fatnino 3y ago
        I'm talking about a big headline mission to survey everything in the vicinity of the outer 2 smaller gas giants. Think Cassini or Galileo (too bad about that antena). Sure these missions take a long time. Means we have to start today so our kids can see the results. All 4 gas giants have plenty of moons with places to land. But I'm not even talking that far out in the future. I just want a suite of scientific instruments in a wide orbit around a gas giant surveying every moon they can get near. Grvity assist slingshot opportunities to get to the outer giants don't come along every decade and yet when one does come up the proposed mission opportunity and it's budget gets instead allocated to yet another damn mars rover.
  - vibrio 3y ago
    What discrete realistic experiment would “definitively rule out” life or water on the entire planet? How many samples would need to be microscopically analyzed to prove the negative?
  - JuanPosadas 3y ago
    > no resources that can be practically mined Asteroid mining would at least have a huge economic payout if achieved.

asdff 3y ago

Microscopy could also be a good route. Microbial life should look pretty distinct from inorganic matter, even if everything in the soil sample were dead by the time it was imaged. As far as I know, we have not sent a microscope up capable of resolving even a large mammalian cell, let alone resolve 1 micron bacteria (if these microbes are even to be similar in size as those on Earth). I suspect the vibrations during launch make it especially challenging to actually get a powerful microscope out to Mars unharmed.

jiggawatts 3y ago
It's very important to NASA to never send anything to Mars that could definitively rule out the presence of life or water. Something I noticed a few years ago is that NASA publishes a press release every month or so with the title "possible hint of water found on Mars". There are literally thousands of such web pages on their site:https://www.google.com/search?q=site%3Anasa.gov+"hint"+"water"+"mars" https://www.google.com/search?q=site%3Anasa.gov+"hint"+"wate... Nobody ought to be this obsessed with something, unless there's an agenda. It's like cigarette companies going on and on about how their latest product is "more healthy". What's going on is that NASA has had a lot of trouble in recent decades maintaining their funding. There's not a lot in space that excites US senators. There's no oil, no resources that can be practically mined, etc... So they have to have some sort of goal, something they have to get funding for so that they can go "look for it". Some NASA administrator picked "water on Mars". Now it has morphed into a reason for the agency to exist, which means if it was ever shown not to exist, then NASA would face a real existential risk itself. So they'll drag their feet as long as possible, sending every possible instrument they can pack into a rover, except for the one that could definitively rule out life and/or water. This is why they didn't send a microscope, and most likely won't send one on the next mission either.
- Fatnino 3y ago
  The next mission is supposed to be sample return. I agree that mars has been over explored to the detriment of all other planets, especially the outer ones.
  - raxxorraxor 3y ago
    No planet you can land on, so that leaves the moons and pluto and the cost is much higher. Not the little extra fuel and hardware requirements, but the mission time alone... Venus is extremely dense and hot that it melts all the equipment pretty quickly, Mercury is hard to reach. Probably very hot too on the very long and sunny days and the nights are too cold. It also require the most fuel to visit without space brakes.
    - Fatnino 3y ago
      I'm talking about a big headline mission to survey everything in the vicinity of the outer 2 smaller gas giants. Think Cassini or Galileo (too bad about that antena). Sure these missions take a long time. Means we have to start today so our kids can see the results. All 4 gas giants have plenty of moons with places to land. But I'm not even talking that far out in the future. I just want a suite of scientific instruments in a wide orbit around a gas giant surveying every moon they can get near. Grvity assist slingshot opportunities to get to the outer giants don't come along every decade and yet when one does come up the proposed mission opportunity and it's budget gets instead allocated to yet another damn mars rover.
- vibrio 3y ago
  What discrete realistic experiment would “definitively rule out” life or water on the entire planet? How many samples would need to be microscopically analyzed to prove the negative?
- JuanPosadas 3y ago
  > no resources that can be practically mined Asteroid mining would at least have a huge economic payout if achieved.