Imagine for a moment that you are a member of an early Mars colony. You’re stranded, and the only way to get a message home is to launch a radio well above the surface. To make matters worse, you’ve got no rockets! It was this thought experiment that has motivated [Thoisoi2] to experiment with making a rocket motor using only ingredients and methods available to your average Martian colonist. The methods he has chosen can be seen in the video below the break.
If you skipped Rocketry 101, a quick refresher might help: Rockets work by burning a fuel in an enclosed chamber and then expelling it at high speed in one direction. To get the fuel to burn more quickly (and therefore adding more oomph to the angry end) a complement to the fuel called an Oxidizer is added. It serves to create an oxygen rich environment for the fuel to burn in. It’s the same reason a oxy-propane torch burns hotter than propane by itself.
Firstly, a stranded Martian would need rocket fuel. If you recall the 1999 movie October Sky, four high school kids used table sugar as their fuel. You might also recall that those tended to get all explody. This volatility caused [Thoisoi2] to eschew sugar as a fuel in favor of a fuel that would also be available to any Martian colonist but be far less likely to cause Rapid Unplanned Disassembly.
What about the oxidizer? In October Sky, the boys experimented with Potassium Chlorate. This is commonly used in rockets but may be more difficult to obtain for your average Mars colonist. But, it turns out that Potassium Chlorate and Sodium Chlorate which can be prepared from table salt will work equally. It’s quite a bit more involved than that however.
Simply adding salt and fuel does not a rocket motor make. The nuances, the science, and the chemistry are all laid out in the wonderful video that [Thoisoi2] has put together, and we are sure you’ll enjoy it as much as we did.
You’ll also get to find out if our stranded Martian ever makes it home or if his potato farming was for naught.
We’d also like to echo the warning in the video: This is an experiment that is pretty dangerous, so don’t try this at home! Definitely try it at somebody else’s house first. Or on the surface of Mars.
Recently Hackaday covered another great attempt at making a rocket motor at home, although this one was a bit less successful, but every bit as interesting!
The Martian atmosphere is quite thin and mostly carbon dioxide. I’m not a chemist but I’m hoping these facts were not overlooked.
The rocket will work *better* on Mars because 1) less atmosphere = less aerodynamic drag 2) Less gravity means… less gravity and 3) rockets provided their own fuel and oxygen, so they can even work in a vacuum. Unless I’ve missed some other point you were making :)
Depending on how he ignites the motor, that may not work in a near vacuum.
Ah! I had not realized that Sodium Chlorate and Potassium Chlorate contained oxygen! Well… I hope Mars explorers take plenty of table salt! ;)
If something uses oxygen from the atmosphere, it isn’t a (normal) rocket. (It could be an air-breathing rocket, but AFAIK nobody has managed to make that idea practical.)
It’s also better because the nozzle can expand into lower pressure, thus the pressure difference is higher and the thrust more.
Also, the ambient pressures at ground level and in space are closer, meaning you can more easily optimize the nozzle for both.
Do you need to use titanium if you are going to plate it with platinum? (Neat project BTW)
“To get the fuel to burn more quickly…. compliment to the fuel called an Oxidizer is added.”
In a rocket, it is to get it to burn at all.
“It’s the same reason a oxy-propane torch burns hotter than propane by itself.”
Yes oxygen free combustion of propane IS disappointingly cool
“This volatility”
first time I’ve seen table sugar described as “volatile”, but you’re right, no one wants an energetic rocket fuel.
One of the struggles of short form writing is deciding which details to leave out, knowing that no matter which ones you choose to omit, somebody will take it upon themselves to offer correction. But as a Hackaday writer, that’s my job: leave out the parts that I think people will be able to understand intrinsically, or be motivated enough to do some of their own research. But since it’s a complex topic, I’ll fill in some blanks here.
It’s true- oxidizer is required in an oxygen free environment, but these experiments were conducted on Earth where we have oxygen in the atmosphere. Many fuels *will* burn without an added oxidizer. Some will not. Same goes for the propane comment. But now the article is too long.
As for the volatility of sugar as a fuel: Volatile is defined as “liability to change rapidly and unpredictably, especially for the worse.” That doesn’t sound like something you want in your rocket fuel. This is evidenced by the video demonstrating that a sugar based rocket got all explody (see the image) and by additional research that I did before writing this article to confirm that yes, sugar is a great fuel if you can tame it. But if you can’t (and it’s hard) then we come back to things getting all explody. And now the article is too long again.
Sugar is not that explody as a fuel, it’s the chlorate, which is a great oxidiser and hard to tame. Sugar with potassium nitrate is rather tame and non-explody fuel (you need to really try to make it explode).
As for struggles with short writing – whole article reads a little incoherent, like you tried to make some mysteries, solve it “The Martian” style but it came out a little awkwardly. I don’t know what exactly could be done better, I could not even do it on your level. I think you just need to write more and experience will come.
Summarizing: thanks for this article, good job and you will get better soon! I wish you all the best.
+1 the part about chlorate being volatile not sugar. Should state the *mixture* being volatile not sugar. Is that too long for you to write?
May be some non-combustive fillers e.g. mud can be added to slow down the reaction?
The other possibility is actually nitrate. They used to make nitrate from manure back in 1700’s Europe and colonial America.
Yes I think the fine detail there is that the mixture is volatile. Thanks for that clarification. There’s always room for improvement when trying to have fun writing about otherwise a fairly dry subject.
My paternal grandfather used a mix of sugar and sodium chlorate (bought as a weed killer) to blast hard lava rock. It burned so fast that a small amount placed on a leaf could burn away without scorching it, but packed into a hole drilled in rock it would detonate and could send chunks of rock up and over a 2 story house. Didn’t get into trouble with the law because it was the 1940’s and 1950’s when the people who figured nobody but *them* knew what was best for everyone else were few in number.
Just FYI from a 13-14 year old way way (way) back, Nitrate/sugar works but all use of sugar at the time seemed to exhibit a large amount of “dross” (mixture issue? humiditt? components?) which when it restricted the nozzle throat sufficiently “got all explody” anyway fairly often, but rarely in a super high velocity way…
Also the Chlorates and perchlorates that were available by mail order for this back in the day and were used as long term weed and brush killers have largely been banned in the US as toxic and long term contaminates (aside from the other reasons)
It was huge fun and still here!
Oh and the sugar mis was melted (outside) to cast the propellant grain to burn slower more controlled, less explody
The most important part about writing scientific article is *scientific accuracy* not length.
Most of the time I found HaD article having a lot of fillers not important to the actual article, so length isn’t an issue. I know writers got to make their own filler to earn their keep.
Yeah, HaD writers are the worst. I would never read HaD.
….wait a minute!
I’m kidding by the way. I love HaD.
Also don’t forget that you are not writing for traditional media, so artificial length isn’t a thing. Make use of hyperlinks to additional articles when you try to explain a difficult concept that can be a full University source by itself. Paragraphs of text can be down to correct keywords and well referenced 3rd party sites.
Get the facts right, don’t confuse your readers and please don’t make stuff up if you don’t know the topic well enough. Yes, it is hard work. Remember you are also an educator…
Anyone with basic reading comprehension skills could see exactly what you’re saying in this article. But this is HAD so there is always some commenter who is looking to show off how “smart” he is..
Hey Ryan, for what it’s worth, I thought it was a very well-written article that was interesting to read. Not sure what all the nitpicking is about.
The oxygen in the atmosphere is irrelevant, there’s no way for it to overcome the exhaust plume and enter the pressurised combustion chamber. The closest thing to that would be a pulse jet or Ramjet. Yes the fuel can burn in the atmosphere, like propane, but only outside the closed combustion chamber, so not a rocket.
It would actually have been shorter to write if you were technically accurate:
“Unlike a jet engine, which burns its fuel with oxygen from the atmosphere, a rocket has to carry its own oxidiser. In a solid rocket the oxidiser has to be mixed with the fuel during manufacture. With all your fuel and oxidiser pre-mixed in the combustion chamber, combustion has to be done in a stable and progressive way, or you have a bomb instead of a rocket.”
I don’t think having chlorine (from electrolysis) of table salt is a good idea in a closed-loop life-support system.
Propane by itself doesn’t burn. The oxidizer is called “air”.
obligatory entertaining read: https://library.sciencemadness.org/library/books/ignition.pdf
Yes! That is a fantastic book. A great introduction to chemistry as well.
+100
As a Tripoli Level 2 Certified rocket person I’m familiar with solid fuel/izer mixes. And their problems. Yeah, you may have what looks like a really good candidate for “rocket mix”, but the FIRST problem you’re going to have is getting it ignited. Even commercially-produced rocket motors have this problem. Besides just being lit off, the motor needs to come up to operating pressure to sustain combustion. If it doesn’t, you get what’s called a “chuff”. Pressurization for motor ignition can be a real problem for people wanting to start a solid fuel motor at reduced pressure, for example in a balloon-lofted rocket, or a multistage rocket that needs to light the upper stages at altitude. Even black powder, used in many ejection charges to expel the recovery system from the body tube, needs to be tightly confined to work at higher altitudes.
Would *love* to get my L3 cert on Mars!
A long video to say ‘ use salt and sealant pushed into a tube to make a rocket’. However since there is virtually no oxygen in the air on Mars, I don’t how this would burn there as claimed.
How did you completely miss all the information about an oxidizer?
Rockets do not use atmospheric oxygen, even on Earth.
s/compliment/complement/ ?
Why are these 2 words confused so often ?
Linguist, please !
The same with pinciple and principal.
Oh, great catch. Fixed, and thanks!
What you are describing is also very nearly an IED/pipe bomb… Also weedkiller and sugar can be detonated by impact, so is dangerous to the user. Maybe this isn’t a problem in the US, but it could get someone into serious trouble with the police elsewhere, not to mention a possible trip to hospital. Please go ahead and delete this comment after mods have read it.
Apologies if I come across as prudish, but this is definitely illegal in the UK without a licence.
Not to forget that, filling a sealed tube with an impact explosive, then (in all probability) shoving a piece of dowel in the other end and whacking it with a hammer, is a literal recipe for losing a hand/half of your face.
“Maybe this isn’t a problem in the US”? Where did you get the idea that the US hasn’t severely restricted freedoms in the name of fighting terrorism?
Rog77: its not illegal in UK unless you have large quantities (danger to neighbours etc), or are using it for crime (blowing up cash machines etc). Simply making your own rocket motors is fine even without an explosives license as long as you can show you aren’t behaving irresponsibly if questioned by the police.
https://mars.nasa.gov/technology/helicopter/ Mars helicopter is a thing…
…and has flown at a maximum altitude of 12 m so far. However, though I haven’t watched the video, I don’t see why this emergency radio transmitter needs to be launched to a high altitude in the first place. Mars has a very thin and dry atmosphere, which shouldn’t make radio transmission from the surface significantly harder than even from Mars orbit.
On Mars I expect to convert the CO2 to Carbon monoxide and oxygen, that is more than enough to power a rocket.
The most common idea i have seen is to get water from ice there, sep the H and O, then use the H with the CO2 in the atmosphere to make CH4 (methane) and liquify the methane and O2. I think that was part of Musks reasons for using this combo
That has been proposed, but I’ve read it’s not actually that good an option due to carbon monoxide and oxygen burning very hot (bad for engine survival) while producing a low specific impulse (bad for efficiency). (My understanding is that burning hotter usually results in higher specific impulse, so this propellant combination seems to be an exception, probably due to the relatively massive exhaust molecules compared to those from hydrogen-containing fuels.)
Hate to pile on, but it’s important to note that Potassium Chlorate is NOT commonly used in rockets; it is rarely used in rockets due to its instability. (Sugar, on the other hand, IS often used as rocket fuel, at least in amateur rocketry).