The Nuclear Rockets That Could Get Us To Mars And Beyond | Answers With Joe

this video supported by curiosity stream last week I revisited the topic of getting to and living on Mars and the different ways to get there faster than what we're doing right now and one of the subjects that came up quite often in comments and I've mentioned it last week was nuclear thermal propulsion I said last week that you might be expecting a video on it soon so here you go I said soon apparently I meant immediately I knew I'd have to do a whole video on it because it's super interesting technology and it's not just about going a little bit faster it really might open up the entire solar system to us and despite me saying that it was theoretical in a previous video they are not theoretical they have been tested it just wasn't the right time for it at the time now we have newer technology as better materials but more importantly a purpose for them could it be time to get serious about nuclear rockets getting rockets into space and navigating orbital mechanics is seriously hard that's why the word rocket science has become synonymous with something very very difficult to do that brain surgery and soccer building a successful rocket is all about the type of fuels that you use different types of fuel have different purposes that work better with different types of payloads like you can get a paper airplane to fly just with the energy that's in your wrist in other words your wrist has enough energy to make that amount of mass take flight but getting tons of metal in a space takes some serious power and with rockets you get that power or thrust by combusting fuel in a combustion chamber and then forcing it out one direction to make the rocket go the other direction yeah I know I'm starting really simple here just just bear with me the tyranny of the rocket equation is that to move more weight you need more fuel of course the fuel adds weight which requires more fuel which adds more weight you can see where this is going and this is forced rocket designers to get really creative over the years to find different types of engines and different types of fuel that create the most specific impulse in other words the most bang for your buck basically specific impulse measures how much a specific amount of fuel and a specific type of engine can create a specific amount of thrust so basically the higher the specific impulse the more thrust you get per unit of fuel specific impulse can be kind of confusing because they measure it in seconds in other words how many seconds of fuel can burn to keep the rocket moving at a certain speed they do this to account for different types of gravity environments that a rocket might be in the whole point is the higher the specific impulse the better large chemical rockets tend to have specific impulses in the triple digits the SpaceX Raptor for instance as an SI at 356 seconds the Vinci engine built the power ESA is Ariane 6 rocket will have a 467 second si atmospheric pressure makes a big difference as well because it compresses the exhaust coming out of the engines so you'll get a different si in outer space than you do here on earth for example a raptor engine gets 356 seconds of si in outer space but down here on earth it's close to the 330 all this is to say that a vehicle has a couple of different sets of challenges one of them is getting up into orbit and the other one is getting around once in orbit over the years chemical rockets have run out is the best way to get things up into orbit but once you're up in orbit it has some disadvantages like the fact that you can only burn chemical rockets for a very short amount of time and the rest of it the vehicle is just coasting and you just kind of hope that it's in the right direction and velocity to get you where you want to be obviously they do a whole lot more than hope but you get the idea flying with chemical rockets is a lot less like actually flying and a lot more like firing a bullet at a target a target hundreds of thousands of miles away besides there's only so much specific impulse you can get out of chemical rockets and if you want more than that then you need more fuel so if we start talking about crewed missions to Mars and beyond we have to start getting really serious about different types of propulsion that could get us there and for that scientists have looked back to the early days of the space race the 1950s and early 60s were kind of the Wild West days for rocketry really no concept was too wild or out there to imagine and this also happened to coincide with another big thing that had just come up around that time nuclear power it shouldn't really be surprising that nuclear power got wrapped up in the space race after all the very first missiles were made to deliver nuclear warheads but nuclear power is a foreign propulsion it's really not as crazy as it sounds the fissile radioactive material that you need to create the nuclear reactions it is orders of magnitude lighter than the liquid fuel that you need for chemical rockets and it can possibly generate si is up into the thousands because I mean you know if you want to talk about bang for your buck that's uh spicy meat-a-ball so how to take this crazy amount of energy and turn it into zum-zum juice well the scientists that have worked on this came up with a lot of really crazy and clever ideas one of which was a consumable rocket that use solid fissile material in the fuel that literally burned itself up as it rose out of the atmosphere and if that doesn't sound crazy enough you can look at project Orion now this is not to be confused with the Orion space capsule that's in development right now the Orion project from the early 60s it actually involved using nuclear bombs to blow up underneath the spaceship and use the force from those bombs to accelerate it higher and higher into the atmosphere I did a video a while back about something called Operation plumb-bob where they did an underground nuclear blast and it apparently launched a manhole cover up into space according to legend anyway well this is like that except instead of a manhole cover it's like thousands of tons of payload and instead of just one nuclear explosion it's you know more than all the nuclear testing we have ever done in history per launch once in space Orien had the potential to reach blistering speeds up to 5% the speed of light in just 10 days possibly 10% the speed of light in about a month at these speeds we could reach Alpha Centauri in only 44 years again the vastness of space is ridiculous but what it's worth though it would be five months shorter than that for the people on the ship due to time dilation so it launches massive amounts of payloads into space and reaches relativistic speeds I mean what's the downside here I mean aside from the massive crater and huge amount of nuclear fallout well here's a downside you can't actually land it because you would literally be diving your spacecraft into a nuclear fireball it's not not a great idea and NASA actually did a lot of tests on this subject and one of its biggest proponents was Freeman Dyson like the Freeman Dyson the spear guy the project was eventually canned and the reason is usually pinned on the partial nuclear test ban treaty in 1963 because that would make it illegal to explode nuclear ordnance in the atmosphere a good story but the truth is it just ran out of funding like I said before it was the Wild West of rockets back in those days all kinds of crazy ideas were being researched and eventually chemical rockets just one out and all these other more you know out there ideas just kind of fell by the wayside although things ever get so desperate that we all have to flee earth with everything that we have don't be surprised if NASA dusts off the plans for the old boom boom machine but the third option for nuclear power kind of turns down the crazy a little bit and actually has a lot of potential and this is called nuclear thermal propulsion this is actually what I talked about with Andy weir in our interview nuclear Energy's always had kind of a Jekyll and Hyde thing going on with the destructive power of atomic bombs on one side and on the other side you know safe fairly clean power that gets all of our homes light Ryan the boom boom machine took advantage of the former this takes advantage of the latter nuclear thermal rockets work a lot more alike the chemical rockets that were used to they heat up a fuel and blast it out of a nozzle to make the rocket go the other direction the fuel is super cold hydrogen and it uses a nuclear reactor to heat it up to insane temperatures like a third as hot as the Sun and much like a Ryan NASA did a lot of tests on this with a project they call Project Nerva which stood for nuclear engine for rocket vehicle application this was actually overseen by Wernher von Braun himself the most efficient test model is called the nrx a6 this actually achieved an SI of 869 seconds which is remarkable like even by today's standards the only thing is it kind of almost destroyed itself in the process that extreme heat I was talking about earlier just cracked several key components in the engine not all the models cracked though a successor engine was called the Nerva XE and it actually did work perfectly 24 out of 40 times NASA actually considered a viable option as a space tug to take large amounts of payload out to the moon or to other places in the solar system budgetary considerations killed Nerva in 1973 by Richard Nixon which at the time overall NASA's budgets were going down because we've reached the moon and interest was waning and it's almost like we just went there to beat the Russians or something speaking of the Russians they had their own Nerva like program that went on from about 1965 to 1994 it resulted in an engine called the Rd o for 10 but budgetary considerations went away at the fall of the Soviet Union so nuclear thermal propulsion such a great idea why didn't it went out why aren't they flying all over the place right now the simple answer is it just wasn't necessary for what we are doing most of the stuff we were doing was in low-earth orbit you don't really need it up there and even when we were going out and sending space probes around the solar system they were unmanned so you could take as long as you want with chemical rockets and orbital maneuvering but now we're starting to get serious about putting human bodies out there in the vastness of space and time is an issue the longer they're out there the more they're in the shooting gallery of cosmic rays and the worse their health effects become Plus technology advanced so much especially material sciences there's materials now that can handle that kind of heat a lot better since they were back in the 60s so now it's becoming a lot more of a possibility that we're looking into NASA's currently in the middle of a three-year contract with the company bwx to supply nuclear fuel for an erv alike program for an NTR engine bwx is actually the same company that provides nuclear fuel for all of our nuclear subs out there in the world in Aerojet Rocketdyne is actually working with NASA on an NTR concept that uses low enriched uranium which would make it simpler to fuel and NASA actually has a design for a hybrid system of a chemical rocket that gets up into orbit and then a nuclear powered engine that gets around the rest of the solar system this was detailed on their game on website and the Russian Space Agency is starting to get back into the game with a program they call tem which actually does not provide propulsion but it's a nuclear reactor to power spacecraft in space which leads to one of the biggest concerns about nuclear rockets is its safety would it be safe for astronauts to be on board one of these things where they get too much radiation out of that I mean astronauts are already you know exposed to a lot of radiation out in space even in low-earth orbit when they're inside the magnetosphere much less when they're outside of that would this just compound that problem now obviously any engine design would prioritize radiation leaks above everything else to prevent that from happening but there's also structural designs for spacecraft that can deflect radiation away from crew compartments in fact some might actually say it's safer because a faster spaceship means less time that you're out there and that cosmic shooting gallery so your overall explosion might actually go down and I think one of the biggest hurdles with NTP ships is just getting people to be okay with launching radioactive material up into space that's been problematic and but it's easy to see why if something went up to a you know the space station with a nuclear reactor on it and something went wrong and they wound up going back through the atmosphere that would be like Chernobyl blowing up in this giant skidmark all the way across the continent right obviously it would be nothing like that you could design the reactor so that it would survive reentry and maybe it would only contaminate a small area and not like a whole continent kind of thing that would still be an issue but it wouldn't be nearly as big but do you think the public's gonna listen to that do you as with all technology there are hurdles to making NTR's safe but it's being worked on so fingers crossed they get those worked out as I mention before we have nuclear ships in the Navy and they use nuclear for the same reasons that we want to use nuclear on a spacecraft you know it can go really long distances without having to refuel nuclear engines nuclear reactors these have the potential to open up the solar system to us in ways that only our greatest sci-fi imaginations were able to conceive of before and who knows maybe the next thing up would be fusion drives once we get that technology down you know in 20 years or so getting up into space getting around in space it's all about velocity 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Channel: Joe Scott

Views: 418,632

Keywords: answers with joe, space travel, nuclear engines, nuclear reactors, NERVA, Project Orion, nuclear propulsion, mars travel, journey to mars, cosmic rays, nuclear rockets, future rockets

Id: ZSNxaWkuoRo

Length: 14min 20sec (860 seconds)

Published: Mon Oct 14 2019