Rocket Lab's Neutron Rocket's Innovative Design Explained By Peter Beck - CEO of Rocket Lab

hello scott manley here and i'm with peter beck of rocket lab and we're here to talk about neutron and everything else rocket lab is up to right how are you peter oh very well thanks scott it's great to check so glad to have you here so yeah earlier in the year uh you ate a hat how did it taste yep it was absolutely terrible when you put a head in the blender like all of the volatiles and the process of making the hat are released so when you pull the top off the blender you just get this this waft of of chemical concoction i don't recommend it i'll i'll try not to do it but i mean it there must have been some uh you know some thought that there was a great experience at the end of it because you got to start building another rocket yeah well look i mean at rocket lab we you know everybody in this company has measured you know do you know do what you say you said you were going to do so it was there was really only one option when uh when when i had such a change of heart that uh you you have to you have to own it for sure so the whole team's on board with this thing oh yeah i mean who doesn't want to build and build a new rocket i mean this is this is this is a dream generally in your career if you get to build one rocket you count yourself lucky but to get to do it twice that's that's very rare so i kind of want to talk about how it's changed from earlier in the year because it was first revealed as this very simple um you know rocket eight tons to orbit it had kerosene it had a different profile and then you came back earlier this month and there was a lot of radical changes to it so i'm actually kind of interested how the process worked did you start with the business requirements and come up with this basic design and then you sent it to the engineers and did they come back or did you contribute i'm really curious how this got that way yeah look so i mean the the the first kind of rendition of neutron was was almost the roots like we knew there was going to be nothing like that um but you know we weren't we went far enough down the design process to um you know to be able to put out what we really you know felt was going to be um the finished article and also we knew it was going to be quite quite radical so um so so we thought well we'll put this whatever we'll put out what everybody would expect and then we'll finish our work and then then release into a much much greater detail but um you know really really how it all started as as you point out is it starts at the customer and one of the advantages of you know flying electron a bunch and building all those relationships with the customers is you get to know um you know you get to know them super well and you get to know the things that that matter and i think as people look at a rocket the often the mistake is um is thinking that the most expensive thing on the rocket is actually the rocket itself and that is when you know that is not the most expensive thing when you go to orbit the rocket generally represents like one-third of the cost when you go to orbit it's actually all the the overhead uh all the infrastructure um that surrounds a rocket that represents more of the value of it so if you if you look at what we've done there you see almost no infrastructure you see no barge you see no uh no strong back no breakover um all of these things actually add tremendous amount of cost and um you know i i'm super fortunate to to to you know be the chief engineer on this project so um we can can really uh you know this is this is really you know probably the last rocket i'll ever design who knows but um so it's it's been it's been super liberating and fun process but you know we all sat around and bought around a whiteboard and there's a couple of fundamentals that that i laid down and probably the thought the thing that drove the design the most was this rocket has to be turned around in 24 hours not not because we actually want to turn the rocket around in 24 hours and fly it but it it drove that constraint drove a whole lot of decisions that ultimately resulted in you know the lowest possible uh cost to get to august so that was the key fundamental the diameter and the shape are a consequence of re-entry so um so it also it all kind of started um trying to try to do the um the mechanisms for the landing legs and uh and i think weak scratching around trying to you know trying to solve that problem because mechanisms suck and um if you can avoid them then that's that's always good so it really neutron in in in its current form was really designed in like one hour on a whiteboard fundamentally because we all stood around the whiteboard and said well landing leads suck so how can we avoid them well let's just make the base wide enough so that we don't have to have them and what you what we actually ended up with was like uh you know it was like a dcx it was a traffic cone yeah dcx i remember that yeah and and it's not surprisingly that dcx ended up like it was because it that was the most efficient design for a single stage to orbit but for us we had different requirements one was no landing legs so you end up with this really wide base and then uh and then of course you know your your upper stage doesn't need to be the diamond of your base you end up with this taper and then as we started evolving that design um you know the the re-entry of that first stage drove more of the requirements than the ascend and if you think about re-entry uh and you know the 24-hour turnaround drove the ability to not launch on a bash it was it drove the return to launch site concept of operations because marine assets i don't know but marine assets are horrifically except it's expensive to operate like yeah really really extensive it costs us way more to put one tiny little ship popping out of the ocean for electron than it does for us to fly out there in a helicopter do a whole lot of operations and come back even pick up a stage so you know marine operations should be avoided at all cost um and so that that that that kind of you know drove uh drove a lot of that that kind of fundamental design and then you know the upper stage is the highest performing stage that you need to produce so um you know putting that inside stage one and putting it all in tension makes it super super light and so you end up with this kind of traffic cone design yeah so uh you said in the neutron presentation that uh the upper stage on neutron is the lightest upper stage ever does that mean it's lighter than the second stage of electron well for for it's first okay i was i was you know i was wondering if you meant that i mean i certainly understand that it's very light it's structure like it's dry mass will be very very good well i think for the upper stage think think of center because the centaur is another you know intention balloon tank hung stage but except accepted made of stainless steel it's made of carbon which is a quarter of the weight um you know and and the great thing about that is it's so light there's no material in it there's no material in it it doesn't cost much um so all of these things kind of come together to to you know to make a lot of goodness so actually yeah there's the design of the rocket is to support re-entry and you told you mentioned on twitter this doesn't have a need for an entry burn to you know reduce the force of the uh atmosphere compared to say the falcon 9. and you believe that it can get away without an entry burn yeah so the thing is the thing that that unlocked return to launch site was was really this um because you chew just a tremendous amount of propellant so there's two burns there's there's one which is the rts ls burn which basically is a flip around and to set us back on the trajectory and then there's a landing burn you might go well how are we getting away with that and um the thing is that re-entering electron has taught us so much it's taught us firstly in how to control um a stage during re-entry just with you know we're just with coal gas rcs and and some some tricks um to basically control that stage during re-entry and it's taught us that if you can control that well enough through that corridor then you can really define and constrain your heating to where you know where you can particularly run a small amount of the launch vehicle now with neutron if you look at it it's it's got a very high ballistic coefficient very big base and it weighs nothing so you know if you're going to go and jump off the roof it's kind of like jumping off the roof with an umbrella you know it's it's very because it's so light i mean it's it's you know it's so wide in diameter you just like electron we let the atmosphere do a tremendous amount of the work and we don't have to we don't have to basically cook it because the deceleration profile is so light is works to our advantage and the there's aerodynamic features on this for uh your steering i presume right you've got the fins at the front uh and or canards depending i mean when they're going when they're actually in use they're not command canards or they're that's right that's exactly right yeah but and then you've also got the the legs two of them extend upwards as straight along the side and are those designed to provide lift right yeah so that that's a kind of our downrange targeting lift lifting body if you will they also serve very useful uh raceways i was going to ask about that yeah yeah yeah so i mean so the upper stage um because there is no strong back that means there is no unbelievable tower so everything's umbilical in from the base um which means uh you know that the upper stage fill and drain lines run up those um run up those raceways to interface with the with the upper stage so will the umbilicals be in the side of the base uh because you know that's your heat shield on the bottom it would seem the best plate yeah okay and so the legs come down i presume they're they can't be carbon fiber because they'll be getting a lot of heat from both entry and the rocket exhaust you're going to have some metal components there yeah yeah but i mean the the majority of the structure is still carbon it's just we run a hot skin on the carbon right okay and the fins will those have to be metal no no no okay okay um so yeah and the the legs they must have some sort of shock absorbers in it right correct yeah yep so there's there's a there's basically a small section of the leaks about 500 millimeters um that uh that is you know shock attenuation um for the uh you know for the landing base so let's talk about the engine because obviously archimedes engine it's rocket labs first like actual turbo pump based engine again are you excited to work on this yeah i mean um i know everybody gets excited about engines but i'm trying to build the boringest engine there there's ever been standpoint the engine on neutron is not exciting and it's it's meant to be not exciting um and if you look at um you know the propellant combination and the you know the cycle this is all about margin it's all about margin and um designing a rocket is a giant engineering compromise and there's you know the you have to decide where the pain is going to be and if you have heavy structures then the pain is in the engines and you end up with engines that have just you know really really pushed if the pain is in the structures then you can kind of simplify now for us um you know we've only even built carbon structures so for us the paint is not in the structures well i mean because it i say that because it struck me that while the rutherford engine did a lot of radical and new things it felt to me like an engineer actually an easier problem to solve than designing like a turbo bump oh man no the rather fit is a springer it is like you know the combustion efficiency of that engine it's really hard to build a really high efficient uh high efficiency small engine it's also when you know as you push the efficiency up um the thermal constraints become higher higher and higher and you know rutherford you know the the smaller the smaller kind of the area you know the the higher heat flux per millimeter square you actually have to deal with whereas a larger engine you have much much uh you know much much more margin on on calling so rubber fit is actually a really tricky engine and because it's a an all uh and canal engine it's not it doesn't have a copper liner um and it's it's so high performance um it that that engine is actually really really tough little engine to um to perfect now um we've done enough engines to know that there's always a demon no matter where you go but um you know a gg cycle locks me thing you know one half thousand psi chamber pressure like it's all just keeps a margin in everywhere and ultimately if you're trying to build a reusable launch vehicle you don't want to be running up near like the yields of shafts and turbo pumps and and like uh you know running throats wide heart of all this kind of you just don't want to be there so that that was the reason for that for the choice so you're going to have seven engines in the first stage um 100 tons of thrust per engine and presume you're going to have to be able to throttle that down a fair amount and control it quickly for landing yeah yeah that that's actually the trickiest part of the the whole the propulsion program is that that throttling range so um you know for the upper stage we have to throw fighter ways back because um you know we'll exceed our g limits and the it's quite quite nice that the upper stage engine throttling requirements match pretty much exactly with the the landing burn engine requirements from a throttle perspective so um so we only need to you know to get that right ones oh so the second stage uh i was going to get some more that's uh as an archimedes engine it's also going to have you know same basically this pretty similar power head i would imagine definitely yeah yeah um any changes to the throat diameter and nozzle for no not not at the moment i mean generally generally you do like even though the relevant is is essentially the same engine there is a small chain a difference in the throat diameter and in rutherford's upper stage so there'll probably be some small small changes there but it largely it will be the same i mean ideally you'll be building more of those because you'll be throwing them away yeah yeah and that that's that that's also a good reason to you know follow a gg cycle is that it's a very inexpensive engine so um for the upper stage i'm presuming you're gonna have it able to re-light once it's in orbit so how are you gonna you perform restart and ignition yeah i mean it's it's no it's no different to you know what we do with with a with a um electron upper stage you have a start basket um to contain propellants and a spin start on the um on the the ggs so it's nothing nothing tricky to say you're going to electrically start the gas generator um buy some gasoline okay okay that's that's what and so the upper stage has to throttle down as well because i if you've got the lightest upper stage and a light payload 100 tons would be a lot of thrust it's actually this is this is one of the the the hardest problems to solve actually yeah i thought it was kind of oversized to be honest like i thought it might be a different engine it actually it actually is it is oversized but the thing is that uh you know like i said before it's always a giant engineering compromise it's awesome for gravity losses uh you know just after staging because you can you can sink all of that thrust in there and you know the upper stage is just super efficient if you look at the size of the upper stage compared to the the first stage it's it's really quite tiny and that's because it's just so grunty and small so you know you you went on you went on kind of negating the gravity losses at the start of the second stage of burn but you lose when you have to throw it back to um you know so you don't you know put the satellite solar panels through its battery pack at the end you're looking at this project going ahead what's your biggest concern about switching over to methane as a propellant i just really the ground handling of it um so look i know i know the i i've never subscribed to the fact that wow if you've got one cryogenic propellant you may as well have two i mean i that that's just terrible like you've got to deal with one cryogenic white earth would you want to deal with two um it doesn't not easier at all i mean there's still there's still a you know delta and temperature between the two propellants anyway that's not useful so you still have to deal with all the same things you have to deal with a room temperature but really what drove me thing was reusability once again so if you look at the timelines and if you look at like from a from a locked carrier perspective one are the things that take a lot of time to be able to turn a vehicle in 24 hours well i mean you have to descend decode um and clean out all of the suits of uh you know of a gas generator cycle or even even in the main tca on our unlocked pyro engine that that takes a huge amount of time whereas if you run lots methane basically you can eat your lunch off of the tca and the gg exhaust so you know it all came down to the 24 turning this vehicle in 24 hours um you know locked care owners it would be a fine choice but it wouldn't meet that requirement the the servicing between flights of the engines just drives that away cool so um how are you going to pressurize the tanks or a genius okay and you're not worried about like uh you know hot gases going in through your uh composite tanks i define hot gases i mean like room temperature no not worried about that at all if i was putting like 150 degrees celsius gaseous oxygen in there i'd think differently but um you know no room temperature warm cold yes however you want to define it not not an issue at all and so yeah rocket lab has worked a lot with carbon fiber over over the years and i'm just curious how has your work how has this evolved since the electron you know has it's i presume you've had changes to your process during the electron program and going forwards i'm just curious if you get anything uh you know are there new techniques formulations are going to be needed for neutron or yeah i mean look we've learned a lot and we've learned a lot in so many areas so firstly like laminate formulation resin systems um you know it was always a really big challenge to to you know we was going to be a really challenge big challenge to think that could we have a a composite system that would be happier cryogenic temperatures and then happy at elevated temperatures when we re-enter and we've already solved that problem with with with electron um and you know cryogenics and composites is a whole whole problem to solve with micro cracking and interlaminar shears and bits and pieces and then it's a completely different problem when you go and elevate our elevator temperatures so all that's all that is sold and composite i sort of said in the movie the composers get a really hard wrap of being super expensive and slow and all the rest of it and that's true if you're like you know one dude in a clean room laying it out and laying it down by hand but when you're doing things like you know automatic tape laying if you've got machines like rosie um man it's fast like to to you know to lay down an upper stage um in in with an automatic five replacement machine you're talking like a day um you're measuring the the you know the build time in meters a minute like it's super super fast and and incredibly incredibly you know reliable and accurate so you know things have moved a long way in the composites industry um from you know guys in a clean room you know hand laying down bits and pieces so it's super super fast and really really cost effective okay and so how does that leave you if you do need to make changes during to the design like how quickly can you turn around so this right this this is the engineering compromise right is that so um if if you wanted to iterate a design over and over and over and over again composites would be the worst decision you could make because the real cost and composites is the tall one so um you know you it's very very difficult to to build a tool and then completely scrape your design and change and iterate and iterate it's right but you know we we tend to iterate at the kind of the component and sub sub assembly level by the time we're building structures we expect that to be right and if you look at our development approach um is is it's not unique but i mean i kind of like in our development pro approach somewhere in between like the traditional uh ulas and whatnot and and kind of spacex it's kind of in the middle you know we fight we have a fail fast philosophy super hardware rich we build lots of hardware but by the time we get to like assembly level we don't expect stuff to fail like the time where we're we're building tanks and rockets and bits and pieces we don't expect it to fail and if you look at like an electron you know the very first electron that we flew looks identical to number 23. there's no fundamental design changes that were made um we failed fast early but once we arrived at the design then it's locked in there is a bit of a tank stretch in the latest isn't there or is that a fearing the fairing that gets stretched you know we put um we put about about 500 millimeters in the upper stage um and that that's just you know as rather than engines are beginning higher and higher performance actually the majority of that was given from batteries um you know battery technology as we predicted was improving so you know we did a we did a new battery program and it just gave us a little bit more performance which you know we're able to to kind of eat some of the mass that um we added for recovery and kind of put us at a net neutral place so i mean i would imagine that given you've got a tapered design on neutron you couldn't simply stretch the tanks without getting a whole bunch of new tooling yeah most of the taper is actually in the in the interstate section because it's such a wide um you know a wide vehicle the the tanks at the bottom um for stage one are not far off spherical but these two big blobs of spheres down there so if we needed to extend an increased tank it wouldn't be wouldn't be that big a deal because it's in basically a parallel um section but um but yeah a little bit of tank stretch here and there is no big deal but if you're fundamentally you know changing the design then it's this this is the trade that you make when you work with composites and actually the neutron design does it use a common bulkhead or is it two separate tanks okay and those tanks go right out to the the the structural wall or okay yeah just but the majority the majority i should try and try and get you a section of it across because the majority of it is actually interstage um versus tanks like because it's such a fat diameter at the bottom that the tents are you know pretty stumpy yeah i imagine there's a fair amount of room in that interstage for you know the supporting hardware right i mean you're going to have the fins that back on to that right yeah and those will have electrical actuators or yeah i mean that that's that's still in trade actually electro hydraulic or just straight electrical is in trade because there's actually quite a lot of systems like that um around the vehicle because the the upper stage is kind of hung off the payload plate um and the way that we we hope to integrate that and of course you've got the hungry hippo faring so the the trade right now is is do we just do a electro hydraulic system for all of those or do we put discrete electrical electrical actuators on each one of them yeah i mean and speaking of that fairing uh obviously a lot of comments were made about uh certain links to james bond and you know you are in new zealand which i'm gonna point out i believe it has a lot of volcanoes a lot of volcanoes great places for a rocket base right yeah do you have a white cat i do not have a wide kit i'm sure somebody at rocket lab does yeah but yeah i mean it shows a four part fairing and that obviously is an early design and i'm wondering what the trades are for our four-part versus a three-part versus the two-part you know yeah yeah yep yep so and i would say that that is that is a hot topic and discussion at the moment whether it's four or four part or or a two part basically what it comes down to is um exit cone clearance so as the second stage is exiting um uh you know out of the interstate and clearing past those bearings the four part gives you the most amount of clearance cone um but there are some nice little tricks with some over sending mechanisms that we're looking at that would enable us to to deal with two it's just that once again it's the trade the simplicity of only having two moving parts versus the complexity of a mechanism or the simplicity of a mechanism but for moving parts right geometrically the two part has to go further out correct but so why not three then because three gets you the same emotion but oh i like even numbers so totally valid reason yeah you know you could i imagine there's like a you know bilateral symmetry in the rocket so a four-way sort of fits probably with everything else yeah so the the four the four pedals is actually hangover um from uh an earlier iteration where we were going to use those pedals as aerobraking um and and actually the original concept that i really pushed hard to see if we could close was to use them as actually control surfaces so we didn't have to have any ford canards and or you know or any actuated thin surfaces but the shape of them is just super ugly and you know they're not good arrow services and getting any kind of tolerance out of them was you know from a control perspective it was just a gnc nightmare so sometimes it's easier to just it's to solve to make to make control much simpler given that control is actually one of the really hard things here uh giving the gnc gnc team a break with some actually some some some fins that they know what they're going to do when they actuate them um is a much place a nice place to be yeah i would just imagine the amount of force you had to put through those to keep them still and stop them flapping you know yeah it was huge yeah yeah it's funny because somebody asked me about that and i rejected the idea of silly so you know i'm happy that somebody thought you thought about it yeah yeah yeah so i mean and that also i would imagine that if they have problems where they can't close will you have a way to eject those so that you can land a vehicle uh no i mean that that's that that's a whole level of complexity we don't really want to have i mean at the end of the day it's a simple simple pivot and a hydraulic ram i mean yep everything can fail but it's a pretty low risk system especially given that the load on them is almost zero um when they're when they're being actuated from the nearest aerodynamic and heating yeah once they're locked in place i imagine there's like there'll be latches between the segments and stuff because you're gonna handle the ascent um and actually i believe during the first neutron presentation you actually talked about possibly making this a human rated vehicle yeah correct and presumably in that case it wouldn't have the fairing it would have a integrated vehicle on top yeah exactly right and it would you could still use the existing second stage but it would just be radically different i then would you be using that given the mass of human human-rated vehicles would that be an expandable launch or you haven't i mean you can you can get you can get some big people on orbit with eight tons i mean you look at soyuz for example yeah so um you know you can you can do some meaningful things um with that i mean if if you need more performance you can you can there's option options to trade yep you can go expendable or you know if you if you really had to you could actually land on land on a barge or something downrange that would that would increase your power performance um a bit but um yeah we think eight tons is there's plenty to get three people on all that yeah it's not not a lot of leg room in the soyuz i'm told but um yeah so that you said 15 tons if it was expandable right and while you say no barges like there's presumably some value in between eight and 15 that you could get from a barge landing uh yeah yeah yeah yeah we'll just have to look at the you know the at the moment that you know we're really um we really kind of organ in on that eight ton class we think that's this is where we're seeing the majority of the um interest from our customer base so um so we think we think that's the right place to be um and you know if we if we if we found that we were wrong we'd probably you know stretch tanks before we would you know introduce um you know downrange assets but it's always it's always an option i mean i guess it's an option and you wouldn't need a radical vehicle redesigned to accommodate it so if the business case worked out you could start renting barges or whatever i i i don't own a ship i just do not but anybody anybody who owns a boat already knows what owning a boat means like ownership is just terrible yeah i live in the bay area there's a lot of that so what we've we've talked a lot about neutron that's it's really cool do you mind uh i'm really curious if you want to talk about photon because we're getting ready for capstone next year right yeah yeah sure yeah i loved it okay well you know what what is the current status like of of photon and hyper curie yeah so i mean it's it's um it's it's getting really close i mean i'm not sure i think we've released some images of the flight vehicle you released a really good looking vehicle it looks grainy yeah now it's beautiful it's all i like to build beautiful things uh so you know that's um so it was it was going through the symptoms vibe test um actually right now yesterday it went up on the vibe table so it's just going through its its final um you know final tvx and vibes and whatnot getting ready for the flight early next year so man that's been a that's been a big program it has absorbed way more uh resources and time than uh than we thought it was going to that like going to the moon is no joke as it turns out it's that's proper hard yeah there's nothing like photon out there with its uh you know interesting engine i guess yeah i mean the hypercarry engine is once again it's it's just super high performance for a tiny little engine um 320 seconds of isp for this tiny tiny little engine is uh is right up there um if you look at all of the kind of the hyper goals and storables you know kissing up in that 320 second range is rare but and and your high procuring has pumps in it right electrical thumbs yeah yeah and so that's partly why you can get that performance because you can get the higher chamber pressures and exactly and like this is the perfect application of electric pumps because we have eight burns to do and you know in between burns we just we just let the sun recharge all the batteries and it's like it's it's just the perfect symbiosis here because you know the sun is just you're just harvesting that energy from the sun you're not carrying it in in a pressure and tank or anything like that it's just makes things so light and efficient i mean imagine it's an extra complication for the you know the navigators to try to figure out long enough between each burn to make sure you can recharge for the burn length yeah i mean it's we we've kind of sized all of the you know the panels that and in the you know to to give us plenty of margin in that respect the the hardest thing with this mission actually well the hardest thing everything is hard but um you know each one of those eight burns um the reason you know one of the reasons why there's eight burns is because we do the burn and then we we use the the impar light radio and uh do the doppler doppler ranging from it to figure out where it is in the universe and then um you know in 24 hours the gnc team has to completely recompute everything again and then we do another burn and then the idea is just to keep you know keep refining that margin right down and then increasing that accuracy right down until the final kind of tli burn which is you know hold onto your seat for that one that's that's it's going to be it's going to be just right but you know it just but you know there's going to be no sleep for the gnc team for like eight days as we do um we do each one of these burns and and re recalculate its position and it's it's quite a unique way um you know to get to where we want to go here in in in really you know use utilizing as much of the earth and the moon's gravitational field to get us to get us in the right place so you know direct inject is is you know is super energy you know um intensive but much much simpler well and yeah you're also going to nrho and that is one of these chaotic orbits you know you're not like apollo where you're just rushing across this hump in the middle you're easing your way through this like hole in space in the geometry yep and so the plan is the plan with the the you're going to deposit capstone satellite and then you're going to go your own way correct and i i don't haven't heard are there instruments you're bringing or is it just uh you know well i mean we have we have camera really that's that's that's an engineering camera yeah yeah and but we also have star trackers so there's there's another couple of cameras there but they're sort of five megapixel black and white cameras but we have we have a that you know the rocket lab payload if you will is a camera um but there's a lot of a lot of other like even just the the you know the ranging radio it's a tremendous amount of learning we can we can do with that and this this is all you know sets us up for the venus mission in 2023 because basically the trajectory is going to a different place but we're using exactly the same um exactly the same process to get there yeah and i mean presumably you'll have to work on the thermals of photon before then for for a venus trip well they actually the the re-entry probe that we're we're kind of depositing in venus is is really the only thing that looks different instead of being a capstone spacecraft on the top um there's there's a there's a re-entry pro well yeah that's that's gonna be great i'm really looking forward to seeing this thing fly and and you know what both missions send us back peter this has absolutely been great to talk to you about all this stuff and i no doubt have like a million other questions afterwards but it's always a pleasure likewise not always fun [Music] [Music] you

Channel: Scott Manley

Views: 220,197

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Id: bVjYHLQtJUE

Length: 36min 22sec (2182 seconds)

Published: Tue Dec 21 2021

Reddit Comments

[u/OldWrangler9033]

I think Manley has the upper hand in this fight.

[u/HolyGig]

I had no idea Proton was using an engine with electric turbopumps and solar to recharge between multiple burns. That's a pretty neat idea