6 ms·
Helium escaping from atmosphere of nearby rocky exoplanet in a habitable zone
- WillAdams 2mo agoIs it wrong that I was hoping for something along the lines of: https://www.scientificamerican.com/article/how-would-we-know-theres-life-on-earth-this-bold-experiment-found-out/ https://www.scientificamerican.com/article/how-would-we-know... except where they are noting how helium is being allowed to escape and not being captured as was previously done by the now shut down U.S. National Helium Reserve.
- burgerone 2mo agoAm I missing something or does that article only contain the back story and nothing actually noteworthy?
- WillAdams 2mo agoIt contains the story of how Carl Sagan convinced the Voyager crew to turn its sensors towards earth so as to see if life could be detected using its quite minimal sensor suite --- I thought it had a link to the original published paper. The fate of the Strategic Helium Reserve is a different issue and there are many articles and op. ed. pieces on it --- the Wikipedia article should cover this: https://en.wikipedia.org/wiki/National_Helium_Reserve https://en.wikipedia.org/wiki/National_Helium_Reserve
- ck2 2mo agowow 50 light years is indeed "nearby" in relative terms nearly 6x the size of earth though, good luck trying to launch a probe off that surface NASA has a neat "exoplanet catalog" which is about to leap in size next few years with new telescopes and techniques * https://science.nasa.gov/exoplanet-catalog/lhs-1140-b/ https://science.nasa.gov/exoplanet-catalog/lhs-1140-b/
- pixl97 2mo ago6x time size (diameter?) or 6 times the mass. Evidently the Earth used to be much larger in size but not mass because of large amounts of trapped hydrogen/helium. It's since leaked from the crust and been blown off into space.
- ck2 2mo agothe catalog says 6.38x mass in one place and 5.6x mass in another they must be able to calculate mass from orbital physics? so you'd need a rocket 6x the size of SaturnV or whatever they are using for Artemis to escape it and most of that rocket is to lift the weight of the fuel for said rocket so it might be physically impossible to build such a creature at current level of tech (might be yet another angle to "why no ETs" unless they are WAY more advanced)
- deleted 2mo ago[deleted]
- inigyou 2mo ago√(G × mass÷radius) [escape velocity] = v_e × ln(m_0 ÷ m_f) [Tsiolkovsky] Impossible to tell how much extra mass you need but it's exponential. Adding a unit of v_e [effective exhaust velocity] to escape velocity means you need 2.717 times as much fuel in an ideal rocket. Earth escape velocity is 11000m/s ignoring atmosphere (which is not ignorable). If the new planet is 6x mass and 2x radius then √3 times escape velocity (about 1.73) would be about 8000m/s extra velocity which is about 3 times a random v_e which means you need about a 25 times bigger rocket. Ignoring the denser atmosphere which makes it even worse.
- shagie 2mo agoFrom the archives ... How much bigger could Earth be before rockets wouldn't work? https://space.stackexchange.com/q/14383 https://space.stackexchange.com/q/14383 Feb 3, 2024 https://news.ycombinator.com/item?id=39243303 https://news.ycombinator.com/item?id=39243303 And related... https://worldbuilding.stackexchange.com/questions/178131/what-is-the-maximum-size-of-a-planet-that-a-chemical-rocket-can-leave-it https://worldbuilding.stackexchange.com/questions/178131/wha... https://physics.stackexchange.com/questions/117347/when-a-planet-has-a-high-gravity-is-it-impossible-to-build-and-launch-a-success https://physics.stackexchange.com/questions/117347/when-a-pl...
- westurner 2mo agoThere is a market shortage of helium but shouldn't be: There's also helium in methane, but unfortunately few places crack out the helium from natural gas. TIL Helium kills Kudzu and powers fusion power plants.
- mapsedge 2mo ago> Helium kills Kudzu That right there is reason enough to try to synthesize it in massive quantities.
- idiotsecant 2mo agoWhen you're done with it can I borrow your particle collider capable of mass synthesis of helium
- adrianN 2mo agoAlpha particles are essentially Helium, so by breeding large amounts of highly active alpha emitters you can produce Helium much more effectively than by fusion.
- actionfromafar 2mo agoProbably that's what they did at the rocky exoplanet. How much radiation do they need down there for it to be measurable as helium in the atmosphere?
- pezezin 2mo agoThe proper way to generate helium is to use a deuterium-tritium fusion reactor.
- westurner 2mo agoGiven the neutron radiation from a fusion reactor, it's possible to synthesize Helium (He4) and more Tritium (T) and 3He using Lithium-6 with Boron-10 and Boron-11. An adjacent vertically-aligned (VA-CNT) battery would last for like 20 years and could power safety systems. A Deuterated Vitrimer pipe with Li-6, B-10, and B-11 could be recycled to extract the T, 3He, and 4He. Deuterated Vitrimers could also be disposed of in a waste burner.
- teeray 2mo agoRocky, you say question?
- King-Aaron 2mo agoAmaze amaze amaze
- js8 2mo agoTurns out aliens love talking funny and safe balloons too.
- mapsedge 2mo agoOnly 880,000 years at our current average speed. Mind blowing, that.
- goalieca 2mo agoThat’s still a few times older than our species.
- Retric 2mo agoSpecies is a rather arbitrary line here. Humans split from Neanderthal ~500k-800k years ago but could still interbreed 40k years ago. We’re likely more closely related to our common ancestors at that point of divergence than Neanderthal suggesting given the opportunity modern humans could interbreed with our ancestors ~500k-1m years ago. Of course that’s just genetic compatibility, there’s plenty of other ways to define species.
- goalieca 2mo agoHomo Neanderthalensis is not Homo sapiens [sapiens].
- Retric 2mo ago> Homo Neanderthalensis is not Homo sapiens [sapiens]. Not the same species, but still capable of occasionally producing viable offspring. Thus the common ancestor as essentially a midpoint between each population would be more compatible genetically. It’s essentially a ring species through time rather than space. https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
- trhway 2mo agoNASA and Starlink have already been using ion drives with 10x ISP of chemical rocket engines. Using such drives a 3 stage with existing nuclear reactors as energy source can get to 150-200 km/s. While it haven't been built yet, nothing seems to prevent ion drive even with 100x ISP of chemical rocket. That means we can get 1000-2000 km/s (acceleration with existing reactors would take about 100 years) and get to the closest star in 1000 years.
- Aardwolf 2mo agoIt would be neat if it were a steampunk-style civilization traveling around their atmosphere in helium airships. But probably just helium escaping from rocks...
- doublerabbit 2mo agoThe transport elevator wouldn't be located in a light house now it?