6 ms·

This paper discusses the design of the helicopter. https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf https://rotorcraft.arc.nasa.gov

by pkaye 6y ago

This paper discusses the design of the helicopter. https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...

everybodyknows 6y ago
Thanks! Fascinating hints at the complexities of working around radiation hazards: >MCU processor units operate redundantly, receiving and processing identical sensor data to perform the flight-control functions necessary to keep the vehicle flying in the air. At any given time, one of the MCU is active with the other waiting to be hot-swapped in case of a fault. >Each subsystem has a current monitor to detect possible latch-up current and can be power cycled to clear a SEL. In addition, current limiting is added to prevent a destructive SEL event and most devices are switched off when not in use to minimize their exposure to SEL. For the critical FPGA which is always on for the duration of the mission, the radiation tolerant ProASIC3 is chosen with the military temperature grade (-55 C to 125 C) and -1 speed grade to mitigate the degradation in the propagation delay caused by the total dose radiation.
- meepmorp 6y ago
  I'm always amazed by the crazy crap people deal with in space, and how much protection the Earth affords us. Extreme temperatures, radiation, small bits of material traveling fast enough to go through structural metals like a knife; it's a thrill a second.
  - martin_balsam 6y ago
    Don’t forget vacuum welding https://en.m.wikipedia.org/wiki/Cold_welding https://en.m.wikipedia.org/wiki/Cold_welding https://en.m.wikipedia.org/wiki/Vacuum_cementing https://en.m.wikipedia.org/wiki/Vacuum_cementing The first time it happened it must have been puzzling
  - lisper 6y ago
    This is an important and highly under-appreciated point. We humans evolved under some very particular environmental conditions, ones which are radically different from space in almost every conceivable way. When people talk about colonizing Mars, I ask them to do the following thought experiment: imagine you are going to move to the Atacama desert. You have to live there for the rest of your life. You get to take one standard twenty-foot shipping container with you. You can pack that container however you like, but you have to live inside the container along with whatever stuff you pack it with for nine months before you can go out for the first time. Figuring out how to make that work is about 100 times easier than colonizing Mars.
    - mlindner 6y ago
      I think that's a poor example. First off, doing such a moving experiment with only your own funds is a lot harder than if you had billions to millions of dollars to do it. Secondly, people won't be trapped inside on Mars and will make regular, if not daily trips outside on EVAs (we may need a new acronym as there's no "Vehicle" here.) Thirdly, a lot of hardware will be outside the "container" including the power generation from nuclear power or solar energy. (Likely nuclear powered sterling engines that have already been demonstrated in subscale versions.) (This contributes to the difference in funds point on my first point.) Fourth, even though you didn't mention it, I'll add it here to preempt a counter argument. The radiation risks are overstated. Radiation on Mars is at least half that of being in space because you have radiation from one half of the "sky" blocked by the planet itself. Also while the radiation levels are certainly elevated, they're likely not going to kill you. Any long term colonies are going to be mostly underground anyway. (Or more likely simply buried by shoveling dirt on top.)
      - lisper 6y ago
        > doing such a moving experiment with only your own funds I didn't say that you had to do it with your own funds. But how exactly do you think that extra money would help? Getting to the Altacama desert is not difficult or expensive. That's the reason that the fact that no one has bothered to even attempt it is so damning. > people won't be trapped inside on Mars I didn't say they would be. In fact, I specifically said that you would only have to spend nine months (the travel time to Mars) inside the container. After that you can go out as much as you like. You don't even have to wear a space suit. > a lot of hardware will be outside the "container" including the power generation from nuclear power or solar energy That's why I gave you a full 20-foot container. But fine, take three containers, which is about what will fit in a Falcon Heavy. Or six. It doesn't really matter. The point is, take some number of containers that you think is a plausible payload for a Mars colony -- and nothing else. > The radiation risks are overstated I never claimed otherwise. There are a zillion other things that will get you before the radiation does.
  - foobar1962 6y ago
    My son is an engineer for a company that makes autonomous fork lifts. One month he was at a client at an aluminium smelter with the machines moving hot metal ingots around; the next month he was at a client that had the machines moving pallets of food product food around a warehouse-sized freezer.

by pkaye 6y ago

This paper discusses the design of the helicopter. https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_AIAA2018_0023.pdf https://rotorcraft.arc.nasa.gov/Publications/files/Balaram_A...

everybodyknows 6y ago

Thanks! Fascinating hints at the complexities of working around radiation hazards: >MCU processor units operate redundantly, receiving and processing identical sensor data to perform the flight-control functions necessary to keep the vehicle flying in the air. At any given time, one of the MCU is active with the other waiting to be hot-swapped in case of a fault. >Each subsystem has a current monitor to detect possible latch-up current and can be power cycled to clear a SEL. In addition, current limiting is added to prevent a destructive SEL event and most devices are switched off when not in use to minimize their exposure to SEL. For the critical FPGA which is always on for the duration of the mission, the radiation tolerant ProASIC3 is chosen with the military temperature grade (-55 C to 125 C) and -1 speed grade to mitigate the degradation in the propagation delay caused by the total dose radiation.

meepmorp 6y ago
I'm always amazed by the crazy crap people deal with in space, and how much protection the Earth affords us. Extreme temperatures, radiation, small bits of material traveling fast enough to go through structural metals like a knife; it's a thrill a second.
- martin_balsam 6y ago
  Don’t forget vacuum welding https://en.m.wikipedia.org/wiki/Cold_welding https://en.m.wikipedia.org/wiki/Cold_welding https://en.m.wikipedia.org/wiki/Vacuum_cementing https://en.m.wikipedia.org/wiki/Vacuum_cementing The first time it happened it must have been puzzling
- lisper 6y ago
  This is an important and highly under-appreciated point. We humans evolved under some very particular environmental conditions, ones which are radically different from space in almost every conceivable way. When people talk about colonizing Mars, I ask them to do the following thought experiment: imagine you are going to move to the Atacama desert. You have to live there for the rest of your life. You get to take one standard twenty-foot shipping container with you. You can pack that container however you like, but you have to live inside the container along with whatever stuff you pack it with for nine months before you can go out for the first time. Figuring out how to make that work is about 100 times easier than colonizing Mars.
  - mlindner 6y ago
    I think that's a poor example. First off, doing such a moving experiment with only your own funds is a lot harder than if you had billions to millions of dollars to do it. Secondly, people won't be trapped inside on Mars and will make regular, if not daily trips outside on EVAs (we may need a new acronym as there's no "Vehicle" here.) Thirdly, a lot of hardware will be outside the "container" including the power generation from nuclear power or solar energy. (Likely nuclear powered sterling engines that have already been demonstrated in subscale versions.) (This contributes to the difference in funds point on my first point.) Fourth, even though you didn't mention it, I'll add it here to preempt a counter argument. The radiation risks are overstated. Radiation on Mars is at least half that of being in space because you have radiation from one half of the "sky" blocked by the planet itself. Also while the radiation levels are certainly elevated, they're likely not going to kill you. Any long term colonies are going to be mostly underground anyway. (Or more likely simply buried by shoveling dirt on top.)
    - lisper 6y ago
      > doing such a moving experiment with only your own funds I didn't say that you had to do it with your own funds. But how exactly do you think that extra money would help? Getting to the Altacama desert is not difficult or expensive. That's the reason that the fact that no one has bothered to even attempt it is so damning. > people won't be trapped inside on Mars I didn't say they would be. In fact, I specifically said that you would only have to spend nine months (the travel time to Mars) inside the container. After that you can go out as much as you like. You don't even have to wear a space suit. > a lot of hardware will be outside the "container" including the power generation from nuclear power or solar energy That's why I gave you a full 20-foot container. But fine, take three containers, which is about what will fit in a Falcon Heavy. Or six. It doesn't really matter. The point is, take some number of containers that you think is a plausible payload for a Mars colony -- and nothing else. > The radiation risks are overstated I never claimed otherwise. There are a zillion other things that will get you before the radiation does.
- foobar1962 6y ago
  My son is an engineer for a company that makes autonomous fork lifts. One month he was at a client at an aluminium smelter with the machines moving hot metal ingots around; the next month he was at a client that had the machines moving pallets of food product food around a warehouse-sized freezer.