I'm creating an Alien race based on Silica-Quartz crystals. While their planet is inhospitable to humans, the tectonically and volcanically active surface has created an abundance of crystalline forms, which have achieved sentience. Their abilities are Piezoelectric in nature, but my biggest hurdle is this...how does a race of sessile crystals send a probe into space? It doesn't need to be anything fancy, it just needs to get up there. :)

Their ecosystem is Silicon based, as opposed to Carbon, and therefore has no fossil fuels as we understand them. They do however have an abundance of Minerals, Metals, Salts, Acids, Alkalines, etc. they have access to. The downside is that their toxic ocean has to bring them the materials they need, though they can create over time formations that help with this. They can't move, but they can grow just about anything silicon based.

So...could they grow a Quartz spaceship, fill it with some sort of fuel, and send it off into space without having it shatter?

  • 3
    $\begingroup$ I don't get the problem. Do you want to say that their entire ecosystem of course (and not a single race, that doesn't make sense) is based on those "crystals" and thus there are no fossil fuels? Or do you want to know about how they do stuff in general since they can't move? If that's so, shouldn't you start at the beginning and establish how they fabricate any tool or anything really and then work your way up to how they do maybe the most advanced stuff we can do today, i.e. sending things into space? $\endgroup$
    – Raditz_35
    Apr 3, 2018 at 11:50
  • 1
    $\begingroup$ Their ecosystem is Silicon based, as opposed to Carbon, and therefore has no fossil fuels as we understand them. They do however have an abundance of Minerals, Metals, Salts, etc. they have access to...basically to us their world is the equivalent of a toxic waste dump. They can't move, but they can grow just about anything crystalline. Think of them as gardeners of a sort, just using different materials. $\endgroup$ Apr 3, 2018 at 12:04
  • 6
    $\begingroup$ I don't think we should get hung up on non-carbon based life implying a lack of fossil fuels. ALL life (carbon based or otherwise) requires a chemical mechanism to store and manage energy, and that mechanism will ultimately result in "fossils" containing stored energy of some form or another. So, essentially, life implies the availability of stored energy (even if you don't want to call it fossil fuel). $\endgroup$
    – dwizum
    Apr 3, 2018 at 14:05
  • 1
    $\begingroup$ Maybe we should ask the Chmrr. $\endgroup$
    – Almo
    Apr 3, 2018 at 21:44
  • 1
    $\begingroup$ @Almo You mean the Chenjesu who then later fused with the Mmrnmhrm? $\endgroup$
    – zovits
    Apr 4, 2018 at 10:51

7 Answers 7


You don´t need a rocket.

Your Lifeforms are much more pressure-resistant than us humans so they could shoot themselves or part of themselves anywhere. They could build up the necessary energy slowly by growing some sort of pressures-chamber or by piezoelectric reaction.

They could also navigate in space by shooting parts of themselves with high velocity in the opposite direction.


(Rocket) science is not carbon-centric. It can be discovered and used by any sentient being.

So your brittle people have only to discover metallurgy, electronic and physics, reach the proper stage in rocket science development and boost a rocket into space, like we flesh-ware based beings did in the past century.

  • 3
    $\begingroup$ Of course... en.wikipedia.org/wiki/… "Silicon, unlike carbon, lacks the ability to form chemical bonds with diverse types of atoms as is necessary for the chemical versatility required for metabolism. Elements creating organic functional groups with carbon include hydrogen, oxygen, nitrogen, phosphorus, sulfur, and metals such as iron, magnesium, and zinc. Silicon, on the other hand, interacts with very few other types of atoms.[10]" $\endgroup$
    – RonJohn
    Apr 3, 2018 at 12:06
  • 11
    $\begingroup$ Specifically, though many rockets use hydrocarbon fuels, others have used hydrogen and oxygen (the Space Shuttle and Delta IV come to mind). Given that crystals usually need water to form, these elements should be present in abundance (and easily extractable with electrolysis). $\endgroup$
    – Skyler
    Apr 3, 2018 at 15:28
  • $\begingroup$ @Skyler that should be an answer. $\endgroup$
    – joojaa
    Apr 4, 2018 at 8:42

They do however have an abundance of Minerals, Metals, Salts, Acids, Alkalines, etc. they have access to.


One thing that you'll soon learn in any good school's chemistry lab is that you should not ❤❤❤❤ with alkali metals. If you have a sample of sodium or potassium you will generally keep it inside a container that is filled with oil, because these ❤❤❤❤s will catch fire if exposed to air humidity. Depending on your setting, they might even explode. They will explode in contact with liquid water:

Sodium spontaneously explodes in the presence of water due to the formation of hydrogen (highly explosive) and sodium hydroxide (which dissolves in the water, liberating more surface).

A small block of sodium can even cause a toilet to crack, and you will probably get a detention by doing that.

Anyway, these elements are so reactive that on Earth, you practically cannot find them in their pure forms outside a lab. Your crystal aliens will probably not be able to find pure sodium as well, but if they have developed chemistry, they may be able to separate it from other elements. If they do, you've got a way to make rocket fuel. Just add water:

$$ 2H_{2}O + 2Na \rightarrow 2NaOH + H_{2} + heat $$

That reaction is exothermic, so you can capture the energy it releases for other processes. The best part is that H2 is a proper, tested-and-used rocket fuel on Earth. It's what propels the space shuttle. Just add oxygen (careful, this is highly explosive):

$$ 2H_{2} + O_{2} \rightarrow 2H_{2}O + boom $$

The huge amounts of energy heat the water into a gas or plasma which shoots out of a rocket's engine as exhaust gases, pushing the ship forward.

Since your lifeforms are crystaline, their rockets would probably need much less life support than those developed by humans. Supposing they have at least the same level of metallurgy as we do, their ships would be much lighter. Tell you what, if your aliens have radio and computers, they will probably be much better at space exploration and colonization than us.

They will need to develop metallurgy, though. Steel does not occur naturally, and crystals are not known for their blast resistance (i.e.: bad for combustion engines).

  • 2
    $\begingroup$ Nice idea. I wonder what specific impulse $4\:\mathrm{Na}+2\:\mathrm{H_2O} + \mathrm{O}_2 \to 4\:\mathrm{NaOH}$ would give. This might actually be usable for a rocket on earth. Perhaps add hydrochloric acid, if only to neutralise the alkaline fallout... $\endgroup$ Apr 3, 2018 at 19:08
  • 2
    $\begingroup$ @leftaroundabout I consider myself good at Physics, but I am far from being a competent chemist - I don't know how to calculate that. If you do find out, I wanna know :) If you do find out, I would be glad if you edited my answer to add that. $\endgroup$ Apr 3, 2018 at 19:45
  • 1
    $\begingroup$ @leftaroundabout, The general rule of thumb is that specific impulse goes up with increasing reaction energy, and goes down with increasing exhaust molecular weight. NaOH is rather heavy as rocket exhausts go, and isn't very energetic compared to something like H2+O2. I'd guess the specific impulse to be well under 100. $\endgroup$
    – Mark
    Apr 4, 2018 at 0:21
  • 1
    $\begingroup$ @Mark I don't know what you mean by “isn't very energetic˘, seeing as the alkali / earth-alkali metals are actually able to burn in both $\mathrm{H_2O}$ and $\mathrm{CO_2}$. (And we could boost the energy further by using peroxide.) Also, $\mathrm{NaOH}$ is lighter than $\mathrm{CO_2}$. I'd reckon the real problem would be that it isn't gaseous, thus doesn't contribute to the expansion – you'd basically have to use just extra water steam as the expanding gas, heated by the sodium reaction. $\endgroup$ Apr 4, 2018 at 9:05
  • 1
    $\begingroup$ @leftaroundabout, incidentally, it looks like an ideal NaOH rocket will have a specific impulse of around 120. The fact that NaOH doesn't want to be a gas doesn't have much impact -- various metal oxides don't either, and beryllium and lithium have both been tested as rocket fuels. $\endgroup$
    – Mark
    Apr 4, 2018 at 23:50

How about Electrically powered spacecraft propulsion

An electrically-powered spacecraft propulsion system uses electrical energy to change the velocity of a spacecraft.

Electric thrusters typically use much less propellant than chemical rockets because they have a higher exhaust speed (operate at a higher specific impulse) than chemical rockets.[2] Due to limited electric power the thrust is much weaker compared to chemical rockets, but electric propulsion can provide a small thrust for a long time.

Now add that your species is high developed in using electrical power.

Their abilities are Piezoelectric in nature

Therefore they might already have develop a much strong electrically powered spacecraft propulsion engine, which even can send stuff to into space.


Space guns might be these crystal critters' best option. Unsurprisingly this answer contains a decent amount of handwaving, primarily on whether on not there exists a growable crystal strong enough to contain immense pressure and how crystals can collect and pressurize some needed gases. But if we're talking about a crystal's space program, I assume a good amount of handwaving is allowed.

Since they can't move and can only grow/collect their tools, they certainly can't create the complicated mechanisms for timing of stages and aeronautics needed by rockets. However, they can (presumably) grow tubes, and put things inside those tubes, so they could make a space gun.

A space gun is what it sounds like: a gun for shooting things into space. Project HARP in the 1960's is the current record holder for space gun altitude. It managed to shoot a 400lb projectile at 8,000mph, allowing it to reach an altitude of 110 miles. I'm not sure what HARP used as a propellant, but I assume carbon was in there somewhere so copying it exactly likely isn't possible for the crystals. NASA's SHARP project from the 1990's is probably a better pattern for your crystals to follow. Instead of traditional gun mechanisms, SHARP is a light-gas gun, which are guns that use expanding gas to force a piston into compressing gas into a very narrow tube containing the payload.

Before being cancelled, SHARP projectiles were expected to reach speeds of 16,000mph, more than double HARP and about 60-70 percent of Earth's escape velocity, and this was just a proof-of-concept for a much larger gun. The best part for the crystals is that the only part of SHARP that relies on carbon was the expanding gas used to push the piston. SHARP used a methane-based mixture of gas that was ignited to produce expansion, however all the crystals need is some non-carbon gas that expands when ignited.

In short, your crystals could design a fairly simple probe launcher in the form of a light-gas space gun: A big tube to hold some gas, a piston to push some other gas through a small tube, and the probe in the small tube ready to be shot to space.


Something based on an Induction Catapult could work:

If that happens, future spacecraft might use a version of a linear induction motor launch system, which essentially is an electromagnetic catapult that would move a spacecraft along a rail system with an air-breathing engine second stage and a rocket-powered third stage completing the job of propelling the vehicle into space, Dryden researcher Kurt Kloesel explained.

One of the biggest barriers to escape velocity on Earth is our thick atmosphere, which might not be a thing on a crystalline, tectonic world. The biggest drawback, of course, is that if the world is very tectonically active, while it would have big mountains (great), it would somehow have to secure the induction rail system against damage from tectonic activity.


Posting as an answer instead of a comment: as L.Dutch said, carbon is not required for rocket science. Though many rockets use hydrocarbon fuels, others have used hydrogen and oxygen (the Space Shuttle and Delta IV come to mind). Given that crystals usually need water to form, these elements should be present in abundance (and easily extractable with electrolysis).


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .