Naked Science Forum
Non Life Sciences => Chemistry => Topic started by: katieHaylor on 01/03/2021 14:11:25
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Ron asks:
Is there any hydrogen to be found in space?
Can you help?
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Yes, but not much - that's why it's called "space".
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Yes, lot's of it. Hydrogen is by far the most abundant element in the universe, accounting for about 90% of the atoms in the observable universe (if I remember correctly). That said, most of the hydrogen is clumped up into stars and gas giants, and is otherwise *very* diffuse. I think something on the order of 1 or 2 atoms per cubic meter in deep space. So there is lots of hydrogen, but so much more space.
(and if your plan is to use the hydrogen as fuel, you'll need to find some oxygen too, and that's gonna be tough!)
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In principle you could collect interstellar hydrogen - or anything else you can find - ionise it with your nuclear electrical generator, and use it as a propellant, with no need for oxygen.
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Is there any hydrogen to be found in space?
Yes, but most of it has proved quite hard to find.
- From models of the universe from the Big Bang to today, cosmologists can predict how much Hydrogen, Helium and Dark Matter should exist to account for the universe that we can see today
- But until the last year or two, the observed amount of Hydrogen was only something like 20% of what they expected should exist.
The earliest discovery, by Cecilia Payne in 1925, was that stars are mostly made of Hydrogen
- She used the optical spectroscope to come to this conclusion
- This upset the astronomers of the time (including her PhD supervisor), who assumed that the Sun had similar composition to the Earth
- This hydrogen is in the form of hot, glowing plasma
See: https://en.wikipedia.org/wiki/Cecilia_Payne-Gaposchkin
More hydrogen exists in the form of isolated hydrogen atoms, consisting of 1 electron and 1 proton.
- This was first observed in the 1950s, when the 21cm "Hydrogen line" was used to map the concentration of these Hydrogen atoms throughout the galaxy, revealing the spiral arms of the galaxy
See: https://en.wikipedia.org/wiki/Hydrogen_line#Discovery
Some Hydrogen exists in the form of Hydrogen molecules, H2. This does not betray its presence by the Hydrogen line.
- This was observed in the 2000s by the effect it has on the spectrum of quasars.
See: https://www.sciencedaily.com/releases/2006/05/060508112217.htm
Some of the hydrogen is in the form of a "plasma" - free-floating protons and electrons, often far apart.
- One way of detecting this is by looking at Fast Radio Bursts (first discovered in 2007)
- as FRBs travel through intergalactic space, the short outburst gets turned into a descending tone, because lower frequencies travel slower through this plasma.
- So it is possible to get an estimate of intergalactic plasma density if you know how far away the FRB originated (a few have been associated with an event whose distance can be measured).
- Progress in these measurements has been made in just the last year or two...
https://en.wikipedia.org/wiki/Fast_radio_burst
There have been more speculative ideas, such as Hydrogen could exist in the form of Hydrogen "icebergs", which could form in cold molecular clouds. As long as these large lumps of solid hydrogen remained in deep space, they could persist, and be extremely difficult to detect.