6 ms·

Well, surely for a certain type of scientific mission (e.g. something like spectral analysis via ChemCam) you cannot just shrink down the components and instrum

Well, surely for a certain type of scientific mission (e.g. something like spectral analysis via ChemCam) you cannot just shrink down the components and instruments indefinitely. The size of Curiosity is directly related to the fact that it is bristling with scientific instruments like no other probe before it. Sure you could make a swarm of toaster sized drones that just go off and cover ground, but the purpose of this mission is not just to take some pictures but to do some very detailed scientific analysis.

todayiamme 14y ago
What you could do is have dedicated drones which are essentially movable instruments, so you can have co-operation on tasks and say teams of 3 or 4 (one vaporises, the other has the spectrometer. One drills, the other has the reagents and so on) If you enter this paradigm then you can eliminate costs such as that long arm which you need to position the instrument package. That arm in of itself is an engineering marvel and it requires a lot of careful design to make sure that it doesn't malfunction. (remember you have a not so light weight at the end, the torque due to that is huge and you have a complex assembly consisting linkages to transfer torque and so on...) The idea of this is to see how simple and redundant you can make things. If for the cost of that arm we could have one small team of rovers wouldn't it be worth it? Wouldn't it jump start exploration?
- deeringc 14y ago
  What you might "gain" in reduced complexity by getting rid of the arm you loose massively in being able to power the whole system efficiently in one go. If you split the 10.6 pounds of plutonium across N smaller drones you would need to duplicate N Radioisotope Thermoelectric Generators (RTPs), power electronics, batteries, radios, cameras, computers and probably a half a dozen other things I haven't thought of yet. This probe is going to be going for at very least 10 years - probably quite a lot longer, all because of the design choices around how it's powered.
  - todayiamme 14y ago
    Again do we need all of those systems? Why can't you have two dedicated machines for earth communication and the rest communicate via a HF radio protocol? You don't need a RTG if it's say sojourner size and packs one payload on a standardised mobile base, solar panels will work just fine. Since you have redundancy built into the swarm you can skimp on a lot of things including computing power. Remember you can use group decision making for more complex "choices" and if you lose a few drones due to unforeseen obstacles, then objectively it shouldn't matter, so you don't need a lot of LIDAR and stuff as well. As far as heating and shielding goes then the smaller size actually works to your advantage. I don't see any reason why someone shouldn't make this. Yes these probes will be disposable, but that's the entire point. They can be used and thrown away opening doors to risk taking that we haven't really seen before.
    - deeringc 14y ago
      > Again do we need all of those systems? Yes. Like I've said above the explicit purpose of this mission is to gather advanced scientific data which requires comparatively bulky instruments and high power availability. Because it is so ridiculously expensive to get anything to Mars you want it to last as long as possible. "Disposable drones" make absolutely no sense when it costs so much to launch them into orbit, transport them 60 million km across the solar system, and then enter the Martian atmosphere and land in a coordinated place on the surface. Each gram you get to that point costs many thousand dollars. You don't just plan your strategy around losing a bunch of them - that would be many hundreds of millions of dollars down the drain. Using a decaying nuclear isotope to power your probe you will get many multiples more bang for buck compared to solar powered probes which so far have maxed out at about 5 years. The solar concentration of a Martian winter is extremely low, and this problem is exasperated the smaller the probe and the resulting battery that it can carry. Just like in computing and electronics, physical and mechanical distributed systems are inherently complex - more so than monolithic systems.
      - todayiamme 14y ago
        >>> Yes. Like I've said above the explicit purpose of this mission is to gather advanced scientific data which requires comparatively bulky instruments and high power availability. Because it is so ridiculously expensive to get anything to Mars you want it to last as long as possible. "Disposable drones" make absolutely no sense when it costs so much to launch them into orbit, transport them 60 million km across the solar system, and then enter the Martian atmosphere and land in a coordinated place on the surface. Each gram you get to that point costs many thousand dollars. You don't just plan your strategy around losing a bunch of them - that would be many hundreds of millions of dollars down the drain. <<< I've thought about what you have said and I think that we are measuring the likelihood of success in different ways. I'm measuring it in terms of the likelihood one pair of devices will complete the outcome at the cost of all the others and, if I am correct, at some level you are measuring it in terms of reducing the possibility of a loss while achieving the mission objectives. I think that we can afford to build disposable machines because if they are tiny and can fit within say a 50 cm cube (which is the diameter of curiosity's wheel) the mass of each machine will also be radically less. Curiosity weighs 899 KG, a well designed vehicle base could weigh as less as 1 KG with instrumentation we could work with the assumption of 2 KG. That is around 450 rovers! If they are divided into teams of say 6 and are dropped off using some method at discrete intervals then you have 75 teams exploring the martian surface. If each team explores during just the warm martian months (I'm working with assumption of 400 sols) with a rate of a very conservative .5 m^2 explored in a day then all of the teams combined will explore 15000 m^2 in the course of a single mission. That's huge. Further, in this scenario, if individual units fail at some point then the entire mission won't be jeopardised and that number will roughly stay the same. I think that if the units are allowed to be autonomous (again because they are disposable) then you could rapidly increase the area explored and get more out of a single mission. In this scenario the success of the mission has now bifurcated from the functioning of a single device and because of that you are free to pursue several orthogonal benefits such as these which ultimately reduce costs. I think that if you factor in a decrease of launch costs due to company's like SpaceX, then this ought to become even more attractive. natep linked to a wonderful article ( http://www.dau.mil/pubscats/ATL%20Docs/Mar-Apr10/ward_mar-apr10.pdf http://www.dau.mil/pubscats/ATL%20Docs/Mar-Apr10/ward_mar-ap... ) on this which argues the point in a much better way. >>> The solar concentration of a Martian winter is extremely low, and this problem is exasperated the smaller the probe and the resulting battery that it can carry. <<< One of the main uses of the battery during winter months is to keep the processor warm. If the assembly is small enough then you should be able to use just insulation, a very small heater and perhaps a long lasting exothermic reaction which proceeds slowly over time. The amount of heat generated by such a reaction would be too small for something like curiosity, but perhaps it might work for a very small machine? Again since tolerances are low you shouldn't you be able to use a wider variety of batteries which store more per unit volume? I might be wrong on all counts, but a smaller design and lowered tolerances might actually work to our advantage. >>> Just like in computing and electronics, physical and mechanical distributed systems are inherently complex - more so than monolithic systems. <<< I'm actually not that into computing and electronics, I used to build physical systems and how they fail fascinates me. My designs failed so often upon meeting the real world that I realised the only way to know if something would ever work was to actually implement it IRL. If you can carry out a mission at one-tenth of the cost then you can do that much more willingly and learn from unforeseeable failure modes much more quickly. It should be an answer to this problem than the other way around.

todayiamme 14y ago

What you could do is have dedicated drones which are essentially movable instruments, so you can have co-operation on tasks and say teams of 3 or 4 (one vaporises, the other has the spectrometer. One drills, the other has the reagents and so on) If you enter this paradigm then you can eliminate costs such as that long arm which you need to position the instrument package. That arm in of itself is an engineering marvel and it requires a lot of careful design to make sure that it doesn't malfunction. (remember you have a not so light weight at the end, the torque due to that is huge and you have a complex assembly consisting linkages to transfer torque and so on...) The idea of this is to see how simple and redundant you can make things. If for the cost of that arm we could have one small team of rovers wouldn't it be worth it? Wouldn't it jump start exploration?

deeringc 14y ago
What you might "gain" in reduced complexity by getting rid of the arm you loose massively in being able to power the whole system efficiently in one go. If you split the 10.6 pounds of plutonium across N smaller drones you would need to duplicate N Radioisotope Thermoelectric Generators (RTPs), power electronics, batteries, radios, cameras, computers and probably a half a dozen other things I haven't thought of yet. This probe is going to be going for at very least 10 years - probably quite a lot longer, all because of the design choices around how it's powered.
- todayiamme 14y ago
  Again do we need all of those systems? Why can't you have two dedicated machines for earth communication and the rest communicate via a HF radio protocol? You don't need a RTG if it's say sojourner size and packs one payload on a standardised mobile base, solar panels will work just fine. Since you have redundancy built into the swarm you can skimp on a lot of things including computing power. Remember you can use group decision making for more complex "choices" and if you lose a few drones due to unforeseen obstacles, then objectively it shouldn't matter, so you don't need a lot of LIDAR and stuff as well. As far as heating and shielding goes then the smaller size actually works to your advantage. I don't see any reason why someone shouldn't make this. Yes these probes will be disposable, but that's the entire point. They can be used and thrown away opening doors to risk taking that we haven't really seen before.
  - deeringc 14y ago
    > Again do we need all of those systems? Yes. Like I've said above the explicit purpose of this mission is to gather advanced scientific data which requires comparatively bulky instruments and high power availability. Because it is so ridiculously expensive to get anything to Mars you want it to last as long as possible. "Disposable drones" make absolutely no sense when it costs so much to launch them into orbit, transport them 60 million km across the solar system, and then enter the Martian atmosphere and land in a coordinated place on the surface. Each gram you get to that point costs many thousand dollars. You don't just plan your strategy around losing a bunch of them - that would be many hundreds of millions of dollars down the drain. Using a decaying nuclear isotope to power your probe you will get many multiples more bang for buck compared to solar powered probes which so far have maxed out at about 5 years. The solar concentration of a Martian winter is extremely low, and this problem is exasperated the smaller the probe and the resulting battery that it can carry. Just like in computing and electronics, physical and mechanical distributed systems are inherently complex - more so than monolithic systems.
    - todayiamme 14y ago
      >>> Yes. Like I've said above the explicit purpose of this mission is to gather advanced scientific data which requires comparatively bulky instruments and high power availability. Because it is so ridiculously expensive to get anything to Mars you want it to last as long as possible. "Disposable drones" make absolutely no sense when it costs so much to launch them into orbit, transport them 60 million km across the solar system, and then enter the Martian atmosphere and land in a coordinated place on the surface. Each gram you get to that point costs many thousand dollars. You don't just plan your strategy around losing a bunch of them - that would be many hundreds of millions of dollars down the drain. <<< I've thought about what you have said and I think that we are measuring the likelihood of success in different ways. I'm measuring it in terms of the likelihood one pair of devices will complete the outcome at the cost of all the others and, if I am correct, at some level you are measuring it in terms of reducing the possibility of a loss while achieving the mission objectives. I think that we can afford to build disposable machines because if they are tiny and can fit within say a 50 cm cube (which is the diameter of curiosity's wheel) the mass of each machine will also be radically less. Curiosity weighs 899 KG, a well designed vehicle base could weigh as less as 1 KG with instrumentation we could work with the assumption of 2 KG. That is around 450 rovers! If they are divided into teams of say 6 and are dropped off using some method at discrete intervals then you have 75 teams exploring the martian surface. If each team explores during just the warm martian months (I'm working with assumption of 400 sols) with a rate of a very conservative .5 m^2 explored in a day then all of the teams combined will explore 15000 m^2 in the course of a single mission. That's huge. Further, in this scenario, if individual units fail at some point then the entire mission won't be jeopardised and that number will roughly stay the same. I think that if the units are allowed to be autonomous (again because they are disposable) then you could rapidly increase the area explored and get more out of a single mission. In this scenario the success of the mission has now bifurcated from the functioning of a single device and because of that you are free to pursue several orthogonal benefits such as these which ultimately reduce costs. I think that if you factor in a decrease of launch costs due to company's like SpaceX, then this ought to become even more attractive. natep linked to a wonderful article ( http://www.dau.mil/pubscats/ATL%20Docs/Mar-Apr10/ward_mar-apr10.pdf http://www.dau.mil/pubscats/ATL%20Docs/Mar-Apr10/ward_mar-ap... ) on this which argues the point in a much better way. >>> The solar concentration of a Martian winter is extremely low, and this problem is exasperated the smaller the probe and the resulting battery that it can carry. <<< One of the main uses of the battery during winter months is to keep the processor warm. If the assembly is small enough then you should be able to use just insulation, a very small heater and perhaps a long lasting exothermic reaction which proceeds slowly over time. The amount of heat generated by such a reaction would be too small for something like curiosity, but perhaps it might work for a very small machine? Again since tolerances are low you shouldn't you be able to use a wider variety of batteries which store more per unit volume? I might be wrong on all counts, but a smaller design and lowered tolerances might actually work to our advantage. >>> Just like in computing and electronics, physical and mechanical distributed systems are inherently complex - more so than monolithic systems. <<< I'm actually not that into computing and electronics, I used to build physical systems and how they fail fascinates me. My designs failed so often upon meeting the real world that I realised the only way to know if something would ever work was to actually implement it IRL. If you can carry out a mission at one-tenth of the cost then you can do that much more willingly and learn from unforeseeable failure modes much more quickly. It should be an answer to this problem than the other way around.