kerbiloid Posted January 8, 2023 Share Posted January 8, 2023 Just now, magnemoe said: The scary part here is carbon monoxide who makes the flammable part sound pretty safe, now I assume most of the CO will become CO2 then the hydrogen is burned. Idk, but the coal gas was being used many years for balloon festivals (and originally for street lamps), and I never heard about street or sky cannonades. Probably, it's relatively safe. Quote Link to comment Share on other sites More sharing options...
DDE Posted January 8, 2023 Share Posted January 8, 2023 10 minutes ago, magnemoe said: Now I could easy see some using hydrogen or an hydrogen mix to save money making party balloons. Well, the extreme guess was commercial propane/butane fuel. Quote Link to comment Share on other sites More sharing options...
magnemoe Posted January 8, 2023 Share Posted January 8, 2023 1 hour ago, kerbiloid said: Idk, but the coal gas was being used many years for balloon festivals (and originally for street lamps), and I never heard about street or sky cannonades. Probably, it's relatively safe. Know coal gas was used for years even for gas stoves in houses and yes people used the stoves for suicide. Outdoor its as safe as hydrogen I say 1 hour ago, DDE said: Well, the extreme guess was commercial propane/butane fuel. Propane is heavier than air, do not store in basements, benefit of propane and butane is that you can store it as liquid. Quote Link to comment Share on other sites More sharing options...
Nuke Posted January 12, 2023 Share Posted January 12, 2023 On 1/7/2023 at 3:46 PM, Terwin said: Complexity is one reason. There are fewer modes of failure if you just increase the size of the solar panels to account for dust accumulation. If you have a gas cannister, it will eventually run out of gas, so if switching that weight to more solar panels will last as long or longer, then solar panels are the simpler solution. After all, our Martian landers have all lasted much longer than the original plan(possibly because they put in additional redundancies if the mission is likely to go under the minimum desired period). perhaps we need to send a helicopter with every probe that has the capability to hover over the panels to clear them. you can place known point targets on perimeter of the panels for position tracking. id like to see more helicopters on future mars probes because that has worked out so well thus far. Quote Link to comment Share on other sites More sharing options...
Terwin Posted January 12, 2023 Share Posted January 12, 2023 1 hour ago, Nuke said: perhaps we need to send a helicopter with every probe that has the capability to hover over the panels to clear them. you can place known point targets on perimeter of the panels for position tracking. id like to see more helicopters on future mars probes because that has worked out so well thus far. How many scenarios will the helicopter mitigate and how long will it last before it fails, compared to increasing panel size by the same amount of weight? Sand storms don't just get the panels dirty, they also block light, Winter also reduces light, will there be enough power to fly your helicopter during that time? I expect that there are hundreds if not thousands of scenarios that will shorten or end the mission, how many of those can you mitigate with your helicopter? Is that more or less than the number that will be mitigated(and by how much) by using that weight for solar panels. You need to remember both the design constraints(very heavily mass constrained for example), and the project goals(Maximum planetary science/$). Every ounce of helicopter, or air bottle, or other mitigation plan will reduce the weight available for scientific experiments and solar panels. A rover designed for maximum life-span looks very different from a rover designed for maximum total science, and maximum total science is far more important for current rover designs than maximum life-span, especially as a longer life-span requires increased ground-support costs, and that will only be paid for if the science/$ is worth while. Quote Link to comment Share on other sites More sharing options...
Nuke Posted January 13, 2023 Share Posted January 13, 2023 we seem to have a really good track record for stretching the mission on these things. but if every mission ends in "er... not enough power" and provides scientific value to the last. it seems you could get more science/$ through longer duration missions and more robust rovers. everyone though sending helicopters to mars was stupid, until they did it and it turned out to be a resounding success. launch a rover (for collecting samples), base station (with science lab), swarms of micro bots for recon and no fewer than 2 helicopters for recon and dust removal and ferrying samples back to the base station for analysis. i think it could work if you could get it all to fit in one launch (potentially cheaper launches in the very near future). Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted January 17, 2023 Share Posted January 17, 2023 If an alien observer had their (analog to current human tech) telescopes pointed at us, but the plane of the ecliptic carried the planets below their line of sight (meaning no transits), would they ebe able to identify the gas giants or terrestrial planets? Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 17, 2023 Share Posted January 17, 2023 3 hours ago, JoeSchmuckatelli said: If an alien observer had their (analog to current human tech) telescopes pointed at us, but the plane of the ecliptic carried the planets below their line of sight (meaning no transits), would they ebe able to identify the gas giants or terrestrial planets? Depends on the distance. There are multiple methods you can use to detect planetary bodies, including direct imaging from close enough and under otherwise favorable conditions. Quote Link to comment Share on other sites More sharing options...
tomf Posted January 17, 2023 Share Posted January 17, 2023 Most extrasolar planets aren't detected by transits but by monitoring the Doppler shift of the parent star. If a star cycles between moving towards and away from you with a regular frequency then that is due to it orbiting around it's common barycentre with a planet. This works as long as your aren't too far of the ecliptic. I believe our solar system would be close to the limits of current detection, the inner planets are to small to move the sun much and the outer planets are too far away so their period is to long to easily detect. Thats why most of the early extrasolar planets were Jupiter sized planets with a period in days. Quote Link to comment Share on other sites More sharing options...
LHACK4142 Posted January 17, 2023 Share Posted January 17, 2023 What's the name of the low-pitched droning aoaowowoaowoaowoaao-ish sound that some planes, especially military ones, make? Quote Link to comment Share on other sites More sharing options...
Gargamel Posted January 18, 2023 Share Posted January 18, 2023 5 hours ago, LHACK4142 said: What's the name of the low-pitched droning aoaowowoaowoaowoaao-ish sound that some planes, especially military ones, make? Ummmm perhaps an example from YouTube or something might help clarify that. Quote Link to comment Share on other sites More sharing options...
18Watt Posted January 18, 2023 Share Posted January 18, 2023 5 hours ago, LHACK4142 said: What's the name of the low-pitched droning aoaowowoaowoaowoaao-ish sound that some planes, especially military ones, make? My first guess (without hearing the sound) is it's two or more propellers which are not perfectly synced. Propeller tips are traveling at or near the speed of sound. As there are a limited number of blades (2, 3, 4, 5, 6..), they produced pulses of sound. We synchronize our propellers to rotate at the same speed for two reasons: It reduces vibrations, more specifically destructive harmonics. That can damage or wear out a variety of components. The REAL reason is that wahwahwahwah noise is annoying as heck. Puts me right to sleep, which is not great as I'm the pilot. So we try to sync the props to reduce that wahwahwah droning noise. By the way, we do that with turbofan engines and straight-pipe turbojet engines too. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted January 18, 2023 Share Posted January 18, 2023 Roaring. Especially when right above houses. Quote Link to comment Share on other sites More sharing options...
Nuke Posted January 18, 2023 Share Posted January 18, 2023 can you improve hydrogen containment by putting a negative charge on the tank? just an idea i had. just dont create any sparks. Quote Link to comment Share on other sites More sharing options...
JoeSchmuckatelli Posted January 18, 2023 Share Posted January 18, 2023 16 hours ago, LHACK4142 said: What's the name of the low-pitched droning aoaowowoaowoaowoaao-ish sound that some planes, especially military ones, make? SFX Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted January 18, 2023 Share Posted January 18, 2023 https://en.wikipedia.org/wiki/Wilhelm_scream https://en.wikipedia.org/wiki/File:Wilhelm_Scream.ogg Quote Link to comment Share on other sites More sharing options...
Gargamel Posted January 19, 2023 Share Posted January 19, 2023 16 hours ago, Nuke said: can you improve hydrogen containment by putting a negative charge on the tank? just an idea i had. just dont create any sparks. I don’t know if I’m answering the question or making it worse, but some quick googling shows there are applications for applying electric charge to liquid hydrogen, so it might be feasible. But now we’re carrying a very large tank of fuel that has a heavy static charge on it. I can see just the static charge alone causing issues. Like rubbing a balloon on a very angry cat full of explosives. Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 19, 2023 Share Posted January 19, 2023 19 hours ago, Nuke said: can you improve hydrogen containment by putting a negative charge on the tank? What would that do? Keep in mind that for a spherical tank, the field inside a charged shell will be zero, making absolutely no impact on the hydrogen contained within. And even for an elongated tank, you aren't going to get much of a field inside for the same reason, the charges on the opposite side partially screening the effect. So you might get a tiny density increase due to polarization near the tank walls, and you'd have to put in an enormous amount of charge to cause this. I'm very skeptical. Unless you have a different mechanism in mind. 2 hours ago, Gargamel said: Like rubbing a balloon on a very angry cat full of explosives. Why is that cat full of explosives? Do I need to call animal protection services? Quote Link to comment Share on other sites More sharing options...
Nuke Posted January 19, 2023 Share Posted January 19, 2023 (edited) just something i was thinking of with regards to hydrogen as energy storage. as i understand it, hydrogen storage is effectively a battery with high self discharge. if by charging the interior it would create a local repellant force which would limit hydrogen loss through tank walls and reduce tank embrittlement, you could stop or reduce hydrogen's tendency to squeeze through things. perhaps there is something you can do with metamaterials. and in my experience some cats behave as if they are full of explosives. Edited January 19, 2023 by Nuke Quote Link to comment Share on other sites More sharing options...
LHACK4142 Posted January 20, 2023 Share Posted January 20, 2023 I wasn't able to find any videos of the sound, but I do have another question: Can we use Ingenuity to blow dust off Perseverance's solar panels? Quote Link to comment Share on other sites More sharing options...
Gargamel Posted January 20, 2023 Share Posted January 20, 2023 1 hour ago, LHACK4142 said: I wasn't able to find any videos of the sound, but I do have another question: Can we use Ingenuity to blow dust off Perseverance's solar panels? Isn’t perseverance nuclear? Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted January 20, 2023 Share Posted January 20, 2023 Let's land the Ingenuity on top of Perseverance and give it 25% throttle. So Ingenuity will be standing on top and vibrating, and thus Perseverance will be shaking the dust down. Quote Link to comment Share on other sites More sharing options...
LHACK4142 Posted January 20, 2023 Share Posted January 20, 2023 54 minutes ago, Gargamel said: Isn’t perseverance nuclear? .... right. Assuming it wasn't, I re-ask my question. Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted January 20, 2023 Share Posted January 20, 2023 14 hours ago, LHACK4142 said: .... right. Assuming it wasn't, I re-ask my question. There's no reason why it wouldn't be possible in theory, but in practice you wouldn't ever attempt that. The risk of the helicopter impacting the rover is just too high. Those blades are spinning at nearly 50 times per second and would absolutely shred the rover if there was any contact. Quote Link to comment Share on other sites More sharing options...
K^2 Posted January 21, 2023 Share Posted January 21, 2023 2 hours ago, sevenperforce said: Those blades are spinning at nearly 50 times per second and would absolutely shred the rover if there was any contact. As someone who once flew a DJI drone into a wing of a foam-body RC plane, can sort of confirm. (I know that's technically all very different scenarios.) Quote Link to comment Share on other sites More sharing options...
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