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.
Species 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.
NASA 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.
It is the four layers of resources, each one is smaller than the next.
1. What is the total theoretical resource?
2. How much of it do we actually now the location of
3. How much is technically recoverable?
4. And most importantly, how much is economically viable?
The last one is really the crux of the problem nowadays, there is a lot of helium but most of it just isn't in a high enough quantity to make the investment to built processing for it. Thus most of it just float off into space.
There will come a point when the price hits high enough to justify the cost but that also means higher costs to the end user.
> 4. And most importantly, how much is economically viable?
But literally the least important factor beyond “should we have started yesterday”. The amount of waste humanity has perpetuated in just the last 100 years because something wasn’t “economically viable” this fiscal quarter makes my head hurt.
Alpha particles are essentially Helium, so by breeding large amounts of highly active alpha emitters you can produce Helium much more effectively than by fusion.
6x 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.
the 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)
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.
Don't these estimates assume launching from the surface, fully via rocket? On Earth, having air breathing stages to gradually build up speed, or using other launch mechanisms, isn't worthwhile because rockets are more cost effective here, but those tradeoffs change if you're on a planet with higher gravity and a denser atmosphere.
You still need to get to escape velocity that doesn’t change the delta v required does but not by that much you are looking at 5-10%. Maybe a bit more if the atmosphere is really really thick.
Unless you skip chemical rockets altogether there is a pretty hard cap on how much bigger a planet can be than earth before a space capable civilization becomes almost impossible.
Is it wrong that I was hoping for something along the lines of:
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.
Only 880,000 years at our current average speed. Mind blowing, that.
That’s still a few times older than our species.
Species 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.
NASA 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.
Rocky, you say question?
Amaze amaze amaze
There 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.
It is the four layers of resources, each one is smaller than the next.
1. What is the total theoretical resource?
2. How much of it do we actually now the location of
3. How much is technically recoverable?
4. And most importantly, how much is economically viable?
The last one is really the crux of the problem nowadays, there is a lot of helium but most of it just isn't in a high enough quantity to make the investment to built processing for it. Thus most of it just float off into space.
There will come a point when the price hits high enough to justify the cost but that also means higher costs to the end user.
> 4. And most importantly, how much is economically viable?
But literally the least important factor beyond “should we have started yesterday”. The amount of waste humanity has perpetuated in just the last 100 years because something wasn’t “economically viable” this fiscal quarter makes my head hurt.
The OP is about helium on an exoplanet. That's unlikely to impact helium supplies on Earth.
> Helium kills Kudzu
That right there is reason enough to try to synthesize it in massive quantities.
When you're done with it can I borrow your particle collider capable of mass synthesis of helium
Alpha particles are essentially Helium, so by breeding large amounts of highly active alpha emitters you can produce Helium much more effectively than by fusion.
wow 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/
6x 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.
the 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)
√(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.
From the archives ... How much bigger could Earth be before rockets wouldn't work? https://space.stackexchange.com/q/14383 Feb 3, 2024 https://news.ycombinator.com/item?id=39243303
And related...
https://worldbuilding.stackexchange.com/questions/178131/wha...
https://physics.stackexchange.com/questions/117347/when-a-pl...
Don't these estimates assume launching from the surface, fully via rocket? On Earth, having air breathing stages to gradually build up speed, or using other launch mechanisms, isn't worthwhile because rockets are more cost effective here, but those tradeoffs change if you're on a planet with higher gravity and a denser atmosphere.
You still need to get to escape velocity that doesn’t change the delta v required does but not by that much you are looking at 5-10%. Maybe a bit more if the atmosphere is really really thick.
Unless you skip chemical rockets altogether there is a pretty hard cap on how much bigger a planet can be than earth before a space capable civilization becomes almost impossible.