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Just curious - why didn’t they test the probe in different types of soils here on earth to see if it would get stuck? Or may be the article is twisting the actu

Just curious - why didn’t they test the probe in different types of soils here on earth to see if it would get stuck? Or may be the article is twisting the actual reason? The article just says “It got stuck because the soil was clumpier than expected”. That can’t be the reason otherwise NASA would have tested it.

zaarn 7y ago
It might have been clumpier than all the mars emulation soil that NASA tested the equipment with.
- mjevans 7y ago
  Setting up an artificial Mars would involve different gravity, air pressure, atmosphere composition, and the weathering patterns of the material are probably difficult to predict. Most of the reason to send a probe somewhere is to learn more about it, so I assume the only knowledge was sparse and possibly inaccurate educated guesses based on other data. That's also probably a good reason to send up a wider tolerance, but less useful design first and follow up with a more targeted design that can do more as a revision on the product. Budgets are probably the reason to not do that.
  - zaarn 7y ago
    There is commercial soil available that mimics the conditions of martian soil fairly well. Gravity can be emulated by hanging the device from a spring (which you can optionally adjust to always take X newtons of force via a computer controller). Atmosphere and weathering can be simulated in a vacuum chamber. All those things can be put into a vacuum chamber to simulate low pressure. This is how NASA is developing their drone for the upcoming missions that will fly on mars and other celestial bodies.
londons_explore 7y ago
Its hard to properly test things with different gravity
- anthonypasq 7y ago
  really depends what you mean by hard here
hanniabu 7y ago
If I'm not mistaken, they do a pre drill test of the soil and then adjust the drill settings for that so it's possible the dirty they tested wasn't an accurate representation of the composition beneath.
ComputerGuru 7y ago
Read your comment again. Clumpier than expected does not mean they didn’t test it, it means they tested it against something that was a poor substitute for the real thing. I’m sure on earth you can find soil both softer and harder. They didn’t make it to work against any kind of soil or rock you could ever encounter on earth because that is optimizing for the wrong thing at the cost of others.

zaarn 7y ago

It might have been clumpier than all the mars emulation soil that NASA tested the equipment with.

mjevans 7y ago
Setting up an artificial Mars would involve different gravity, air pressure, atmosphere composition, and the weathering patterns of the material are probably difficult to predict. Most of the reason to send a probe somewhere is to learn more about it, so I assume the only knowledge was sparse and possibly inaccurate educated guesses based on other data. That's also probably a good reason to send up a wider tolerance, but less useful design first and follow up with a more targeted design that can do more as a revision on the product. Budgets are probably the reason to not do that.
- zaarn 7y ago
  There is commercial soil available that mimics the conditions of martian soil fairly well. Gravity can be emulated by hanging the device from a spring (which you can optionally adjust to always take X newtons of force via a computer controller). Atmosphere and weathering can be simulated in a vacuum chamber. All those things can be put into a vacuum chamber to simulate low pressure. This is how NASA is developing their drone for the upcoming missions that will fly on mars and other celestial bodies.

londons_explore 7y ago

Its hard to properly test things with different gravity

anthonypasq 7y ago
really depends what you mean by hard here

hanniabu 7y ago

If I'm not mistaken, they do a pre drill test of the soil and then adjust the drill settings for that so it's possible the dirty they tested wasn't an accurate representation of the composition beneath.

ComputerGuru 7y ago

Read your comment again. Clumpier than expected does not mean they didn’t test it, it means they tested it against something that was a poor substitute for the real thing. I’m sure on earth you can find soil both softer and harder. They didn’t make it to work against any kind of soil or rock you could ever encounter on earth because that is optimizing for the wrong thing at the cost of others.