So I had this idea for writing a science fiction story about the discovery of a material that enables extremely high accelerations and I want to know this to set up a plot.

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    $\begingroup$ The answer probably depends on what exactly "cannot be found on Earth" means. In principle you can find every element in the cosmos on Earth - it's more a question of abundance. $\endgroup$ Commented Apr 24, 2023 at 10:46
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    $\begingroup$ A material, or an element? The distinction is fairly important. $\endgroup$
    – ProfRob
    Commented Apr 24, 2023 at 13:40
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    $\begingroup$ You can check Worldbuilding.SE $\endgroup$ Commented Apr 24, 2023 at 16:49
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    $\begingroup$ Discovering unobtanium in the outer solar system is as likely as your story needs it to be. $\endgroup$
    – RonJohn
    Commented Apr 24, 2023 at 19:33
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    $\begingroup$ @VLAZ 1. The premise of this question is fictional 2. I haven't suggested OP to post the same question in WB. I just recommended OP to check if they can find any related posts which can be helpful. 3. WB is definitely not a dumping ground and I also didn't mention that this question is off-topic here. 4. Based on the answers, the reality aspect doesn't seem promising. $\endgroup$ Commented Apr 25, 2023 at 16:41

5 Answers 5


New elements might be found in the crusts of neutron stars, new isotopes of known elements certainly will be. But they can't be brought to the Solar System.

Under conditions of extreme pressure and density ($>10^{14}$ kg/m$^3$) the valley of nuclear stability in the $N$ (neutrons) vs $Z$ (protons) shifts towards more neutron-rich stable nuclei and the peak of the binding energy per nucleon curve shifts towards elements/isotopes with higher $Z$ and much higher $N$.

Unfortunately, should these elements be removed from their high density environment, they will (explosively) revert to their constituent particles, or if removed in a more gradual way, will decay back towards the more "normal" heavy elements we find in low-density environments (like here on Earth). The sudden release of neutron-rich material in the collision of two neutron stars is now thought to be one of the ways in which heavy elements are produced and dispersed into the cosmos.

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    $\begingroup$ Which neutron stars are known to be in the outer solar system? $\endgroup$ Commented Apr 26, 2023 at 1:35
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    $\begingroup$ None. And my answer is none. "...should these elements be removed from their high density environments...", which is what happens in a kilonova explosion @planetmaker. $\endgroup$
    – ProfRob
    Commented Apr 26, 2023 at 5:28

This question is probably better suited to Worldbuilding SE, but here are some suggestions.

  • Some element from a superheavy Island of Stability. There once were claims for the natural occurrence of element 126. This hypothetical element's placeholder name is "Unbihexium", which seems like a great science fiction name.
  • Perhaps even better would be quark matter elements from the Continent of Stability. If it exists, there actually are plausible ways it could naturally occur, so maybe a couple of quark matter stars smashing together could produce accessible chunks of it.
  • Some natural compound. For example, when high temperature superconductivity was discovered, it was noticed that it had perovskite structure. Since many perovskite minerals exist, I heard (not very serious but also not completely ridiculous) speculation that we should search for room-temperature superconductors in nature. As it happens, perovskite grains are formed by cooler stars and brown dwarfs, so perhaps there could be clouds of room-temperature (or higher) superconducting dust floating out there.
  • You don't specify how the material "enables extremely high accelerations". It is perhaps not impossible that life that evolved on an massive high-gravity planet could provide biological compounds that help humans survive extremely high accelerations.
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    $\begingroup$ Hypothetical element 126 has the temporary placeholder name ‘unbihexium’, which just means ‘element 126’ — if actually discovered, a permanent name would be chosen. (For example, I remember when element 104 was known as ‘unnilquadium’; it's now ‘rutherfordium’.) In the fictional universe of the story, it would presumably have been discovered and accepted, and so a permanent name would have been chosen — one which the author could make as plain or exotic as they chose. $\endgroup$
    – gidds
    Commented Apr 25, 2023 at 14:13
  • $\begingroup$ I started to go in on this question, but then I bumped into the heavy theoretical "island of stability" elements like Unbinilium, and ... well ... I guess there's no reason why there couldn't be some body out that that has a cache of it or something similar. Like a captured body from a dead system that was many stellar generations older than ours. It seems super unlikely, but in a unimaginably large universe the super unlikely is an everyday occurrence. $\endgroup$
    – T.E.D.
    Commented Apr 27, 2023 at 15:51
  • $\begingroup$ For a fun task, if you find a captured planet in your system that has super useful heavy elements, and you discern that it must have been ejected from a stellar system that was rich in such elements, it seems like it would be worth someone's while to try to figure out where the REST of that stellar system was, and where it can be found now. $\endgroup$
    – T.E.D.
    Commented Apr 27, 2023 at 15:58
  • $\begingroup$ @gidds: IMHO, Avatar would have been better if the first mention of the mineral name "unobtanium" had been replaced with "unbihexium, informally called unobtanium". It would be for story purposes plausible that it might be more stable than present theories would suggest, but that it would be extremely rare and have some very valuable properties, and also that there may be sufficient disputes about what it should be called that the numerical name is retained for formal usage. $\endgroup$
    – supercat
    Commented Apr 27, 2023 at 17:38
  • $\begingroup$ @gidds since this is a fictional world, we could assume that element 126 would retain that name in the story, allowing the catchy title to be retained. $\endgroup$ Commented Apr 27, 2023 at 17:43

Almost zero because the Earth has interacted with rock, ice and gas and dust that exist in the solar system for more than 4 billion years so any element is likely to be here. The heavier unusual radioactive elements like californium have a short life and won't be around in space. Your only hope is that dark matter is some kind of new element which bizarrely doesn't interact with light.

You might find an unusual chemical compound or molecule on a planet or asteroid.

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    $\begingroup$ That's wrong. Helium has its name (from Greek helios = Sun) because it was first discovered via spectroscopy in the Sun as lines which could not be explained by any known elements at that time. $\endgroup$ Commented Apr 24, 2023 at 10:47
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    $\begingroup$ @planetmaket. Yes I should have said in recent times because there has been so much observation now. $\endgroup$
    – user50623
    Commented Apr 24, 2023 at 12:00
  • $\begingroup$ It would have to be some element in the hypothesized island of stability, $\endgroup$
    – DKNguyen
    Commented Apr 24, 2023 at 21:12
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    $\begingroup$ @planetmaker: Yeah, but helium is present on the Earth, though it was not identified as such before being discovered in the Sun. $\endgroup$ Commented Apr 25, 2023 at 5:31

New elements on the outer Solar System? Not so much. But different types of molecules are commonplace on lots of places other than Earth. Just a few examples:

Perchlorates on Mars

On Earth, we jump through electrolytic hoops to make perchlorate artificially, but on Mars it's right there in the dirt:

Martian soil is toxic, due to relatively high concentrations of perchlorate compounds containing chlorine.[1] Elemental chlorine was first discovered during localised investigations by Mars rover Sojourner, and has been confirmed by Spirit, Opportunity and Curiosity. The Mars Odyssey orbiter has also detected perchlorates across the surface of the planet.

Strange Sulfur on Io

Volcanic action produces volatile sulfur-bearing species that cannot survive the moisture and oxygen on Earth's atmosphere (you get sulfates) but can persist on the Jovian moon Io. Disulfur monoxide, forms a substantial part of the volcanic gases on Io and may even appear in condensed form there (note also the mention of diatomic sulfur gas instead of the usual octasulfur):

Volcanoes on Io produce substantial quantities of S2O. It can form between 1% and 6% when hot 100-bar S2 and SO2 gas erupts from volcanoes. It is believed that Pele on Io is surrounded by solid S2O.[2]

Triatomic sulfur, S3 is also found in Ionian eruptions, as well as on Venus in combination with other out-of-this world sulfur molecules:

S3 occurs naturally on Io in volcanic emissions. S3 is also likely to appear in the atmosphere of Venus at heights of 20 to 30 km (12 to 19 mi), where it is in thermal equilibrium with S2 and S4.[3, p. 546] The reddish colour of Venus' atmosphere at lower levels is likely to be due to S3.[3, p. 539]

Carbon monoxide on both Mars and Pluto

This notorious poisonous gas is known on Earth as essentially a high-temperature molecular fragment, formed by incomplete combustion processes (sometimes on purpose) and tending to disproportionate releasing carbon soot when cooled. Not so on some other celestial bodies.

Carbon monoxide in the Martian atmosphere is produced by photolysis of carbon dioxide:

Carbon monoxide (CO) is produced by the photolysis of CO2 and quickly reacts with the oxidants in the Martian atmosphere to re-form CO2. The estimated mean volume ratio of CO in the Martian atmosphere is 0.0747%.[4]

The released oxygen may form oxidized species in the atmosphere or perhaps in the soil, including the aforementioned perchlorates.

Carbon monoxide also appears in the ice on Pluto, including the famous heart-shaped Tombaugh Regio [5]. This may be evaporated along with other volatile molecules into Pluto's atmosphere.

Cited References

  1. June 2013, Leonard David 13 (June 13, 2013). "Toxic Mars: Astronauts Must Deal with Perchlorate on the Red Planet". Space.com. Retrieved April 28, 2021.

  2. Nakayama, J.; Aoki, S.; Takayama, J.; Sakamoto, A.; Sugihara, Y.; Ishii, A. (28 July 2004). "Reversible disulfur monoxide (S2O)-forming retro-Diels–Alder reaction. disproportionation of S2O to trithio-ozone (S3) and sulfur dioxide (SO2) and reactivities of S2O and S3". Journal of the American Chemical Society. 126 (29): 9085–9093. doi:10.1021/ja047729i. PMID 15264842.

  3. Lewis, John S. (2004). Physics and Chemistry of the Solar System. Academic Press. ISBN 9780124467446.

  4. Franz, Heather B.; Trainer, Melissa G.; Malespin, Charles A.; Mahaffy, Paul R.; Atreya, Sushil K.; Becker, Richard H.; Benna, Mehdi; Conrad, Pamela G.; Eigenbrode, Jennifer L. (1 April 2017). "Initial SAM calibration gas experiments on Mars: Quadrupole mass spectrometer results and implications". Planetary and Space Science. 138: 44–54. Bibcode:2017P&SS..138...44F. doi:10.1016/j.pss.2017.01.014. ISSN 0032-0633.

  5. NASA (7 July 2015)"Frozen Carbon Monoxide in Pluto’s 'Heart'", https://www.nasa.gov/image-feature/frozen-carbon-monoxide-in-pluto-s-heart. Retrieved 24 April 2023.

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    $\begingroup$ In the case that OP was actually asking for materials/compounds instead of elements (which I hope so since the question for elements is a 5 second google search) this is the right answer $\endgroup$
    – Hobbamok
    Commented Apr 27, 2023 at 15:07

The question is whether you look for element or for isotope or molecule or material. In both former cases, the answer is "you can find any naturally occurring element or isotope on Earth". Yet the abundances do vary somewhat among different solar system bodies, so it might be viable in some future to dig or harvest some more exoctic isotopes from other solar system bodies than Earth.

One example which is thought to be a viable resource the Moon could provide is Helium-3 which was embedded in the upper layers by the solar wind in the billion years past its formation. It could be used potentially as fuel in future fusion reactors.

Generally, the protoplanetary nebular was relatively homogenous, yet the heavy elements have different condensation temperatures. As such you find the inner solar system depleted in volatile elements (those with a low condensation temperature) as the protoplanetary disk was hotter near the Sun than far out. Thus it might be viable to mine further out in the solar system for some volatile elements (e.g. water, but also rare earth elements like Yttrium, Neodynium, Europium etc). On Earth also the overall abundance is not so important for mankind as is the abundance in Earth's crust. That means that many of the rare elements are relatively depleted in the mantel and enrichted in the core as they sank to the core as they are heavier than the now silicate - rich mantle material.

You find a brief overview over the different of the origin of volatile elements on Earth in this Nature article by Broadley et al - that's where you might find them still today. In the smaller outer-solar-system bodies the differenciation (thus sinking of heavy elements to the core) did not happen as they are much smaller - so the relative abundance of the volatile and rare earth elements is higher. That might be interesting.

Thus: finding something economically interesting, likely will happen in some future. However finding a completely new element - that's unlikely. The element table is pretty well charted, even beyond the naturally occurring elements and isotopes. Things might look different, if you are not talking about elements but about compound materials, thus molecules, rocks or similar. The possible variety is endless and it's certain that not every possible mineral or material has been discovered.


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