Can SpaceX Reuse a second stage?

SpaceX makes first stage recovery and reuse look routine these days. In March, Elon Musk said he wants to start trying to recover and reuse the second stage... Why is that a bigger deal than the first stage? Find out!
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[@Eversoncars]

It’s funny to watch this now and realize how much Tim has grown as a content creator

[@wilboersma9441]

I miss the suit tho

[@ryannaru1]

In your first heat shield attempt, I think you'd find that your center of mass was closer to the engine, as KSP distributes fuel mass top down. However, in real life if you were decelerating like that, the fuel would likely pool up in the front near the heat shield, moving the COM forward and providing a more stable configuration, with less demand on RCS.

[@limiv5272]

At that point there won't be much fuel left, so it might not make that much of a difference

[@harbingerdawn]

"It takes the same amount of fuel to slow down using retropropulsion as it does to get to orbital velocity in the first place". NO!!! Very much no! The *delta-v* requirement is the same, but the propellant requirements are much different - when achieving orbit, you need enough propellant to loft the stage, AND the payload, AND the additional propellant for the return journey. When coming back, you only need enough propellant to slow down the stage. Which in no way changes the point about retropropulsion being a bad way to go, I just thought some clarification was warranted.

[@EverydayAstronaut]

+HarbingerDawn you're exactly right I just misspoke and meant to say takes as much delta V, not fuel

[@Ntropic]

At least add an annotation for the mistake!

[@trainsfemme]

Actually, same delta V is incorrect as well. The Soyuz only has a 123 M/s deorbit burn.

[@24kGoldenRocket]

HarbingerDawn...He is forgetting Drag. Space Shuttle only required enough propellant for a Delta V of -250 mph...roughly 1/74th of LEO Velocity...in order to deorbit if i recollect correctly. (18,500 mph to 18,250 mph.) The atmosphere did the rest of the work. (Work is just another way of saying Energy.) There is atmosphere up there. During one time I was watching a Shuttle mission on NASA TV i watched a Delta V of +250 mph in order to increase the altitude of a Shuttle. It was a 30 second or so OMS burn. They had the cameras pointed toward the aft overlooking the payload bay. And they did the burn during a "nighttime" pass. Well...the leading edge of the tail...glowed red hot. I will never forget that sight. I was not expecting that.

[@24kGoldenRocket]

Victor Csr...There is a major difference in the velocities when comparing a First Stage Recovery to a Second Stage Recovery. A Second Stage cannot be deorbited by propellant alone. The speed of the Second Stage is a SUM of the speed of the First Stage (due to the use of the propellant burned in the First Stage) which is added to the speed due to propellant burned in the Second Stage. The Second Stage would have to be much larger than the First Stage to depend exclusively on burning fuel to deorbit. So Musk will have to depend on aerobraking to recover the Second Stage....if that is what he wants to do. Thus it is a poor assumption. But even that issue needs to be moot....and put to rest. Retrieval of the Second Stage is a poor strategy. It is better to leave them parked in LEO so that you already have hardware up there that you can repurpose. Why spend the fuel to retrieve them...and the spend even more fuel to get them to orbital speed again? Park them. We do want to go to Mars, right? They can be used for that. It is about energy. Spaceflight is all about energy and the efficient use of it. Brute Force, while it works, is not cost effective.

[@SpecialEDy]

I have 4000+ hours in KSP, and I guess I have no life...

[@Ctaehko]

Link me your steam profile.

[@aawqaq620]

@@Ctaehko LOL!!!!!!!

[@Jaiden_floydlive]

Same but I have 5693

[@joaquinlaroca2886]

LOL and i thought that 200 hours was a lot

[@pappamu3725]

Yes

[@TheEventHorizon909]

Kerbal Space Program is always the solution. Also, SpaceX is now considering reusing the second stage. We could just use some superdracos and Heatshield/gridfins to slow down.

[@borisssman]

Not when you're trying to study! why you so addictive ksp

[@DCsk8rgoelz]

+

[@glubothemad]

It's not that addictive after first few thousand hours -- oh wait :D

[@dosmastrify]

TheEventHorizon add.more.boosters.

[@MrFerrariF360]

And struts, don't forget more struts.

[@dosmastrify]

duuuude he is not kidding about DON'T PLAY KSP IF YOU WANT A LIFE "annnnd that took me way too long" yes, this too is an important central aspect of KSP

[@obliteron]

Go for it! You'll feel as great as Gagarin when you return your first capsule!!

[@spacecadet35]

I had a choice, Kerbal or my own private Space Programme. I chose the later.

[@iciclefox9901]

Elon, stop changing your name! *this is a joke*

[@rmkenney]

Easy. Inflatable heat shield. 1) Dual membranes are deployed by a half-circular arm from the body just above the engine. Like a windshield wiper blade on steroids. Arm sweeps down, out, over the engine, and then back to the other side of the body, wrapping both membranes over the engine. Arm is grabbed/ locked by some mechanism on the other side of the body. 2)Then the expanding foam filler is injected between both membranes. 3)Depending on the differing tensioning and the timing of the tensioning of the two membranes, you shape the foam plug. 3a) Initially, the outer membrane is kept tight, inner membrane left loose. Foam forces the inner membrane to conform to the shape of the engine nozzle and thrust plate(?), so that it is solidly attached to them. 3b)Then once a sensor on the thrust plate detects that the membrane has been forced down against it, the outer membrane is then slowly detensioned to allow the heat shield to take the proper mushroom shape. So the heat shield is: a) kept from sticking permanently to the engine nozzle, making it a mess to remove(assuming they can recover the second stage in the first place). b) the now-solid foam core is more or less surrounding and conformed to the engine nozzle, so it's not going to float free under the forces of reentry, plus it's "attached" to the(previously noted) heaviest part of the second stage, so it will be in a aerodynamically stable location on the stage. c) the outer membrane and foam core, if wide enough, can slow down and protect the second stage through re-entry. Now it's just a matter of a parachute for the last few miles through the atmosphere. You've used virtually no fuel except for the initial deorbit, and the mechanism is cheap enough that if it doesn't work 100% of the time, you haven't lost anything. Also, if it lands in the ocean, the most expensive part(the engine) is nicely wrapped and encased(like a christmas present), keeping it from corroding. Or slowing down that exposure, anyways. EDIT: I should have added that as long as the inflatable heat shield fully conforms to the engine, even if the rest of the second stage blows up or burns up during reentry due to whatever(instability?), the engine(the most expensive part) is wrapped up in that coccoon of protection.

[@musaran2]

"Easy" Proceeds to 12 paragraphs of explanations.

[@anamarte9859]

Bruno Mailly what did you expect it’s rocket science

[@aiden22theastronaut72]

Seen your content ever since this video, I had just got out of sixth grade and was feeling really bored one day so I scrolled through youtube and saw this video on my recommended. That day, you became my favorite youtuber. I am now a sophomore in high school and I still watch your content, luckily, your content has made subjects become more easy to understand while being fun and engaging. The best part about you is that you actually care about your content, which is seen only in a few people today. Thanks for truly bringing space down to earth for everyday people like me.

[@EverydayAstronaut]

Aiden! You rule and made my day! Thanks so much for saying hi and for cheering me on. It honestly means a lot to me! Thanks so much for watching 🙏

[@borisssman]

this guy really needs more followers

[@EverydayAstronaut]

+borisssman haha thanks!!! 😊🙏

[@spiritusinfinitus]

He just got one more... Me!

[@manumus11]

i just pushed the button .. and nothing blew up !! nice vid great ideas !!

[@spoonikle]

He is so lopsided... I am freaking out. I didn't think I cared... but its so bad I can't watch - only listen

[@satterar]

have the reentry done with heat shield on the side...

[@marsrobotcs]

Glad I discovered your channel!

[@EverydayAstronaut]

+Eric Mendez thanks Eric! Glad you did too 👍

[@illliiiiillliii6265]

Everyday Astronaut 10/10 kerbal space program content👌

[@liambeckett7123]

Everyday Astronaut Where did you get your flight suit?

[@christopherbeen2358]

So do i, very informational

[@falafeldurum2095]

@@EverydayAstronaut As far as I know, a Falcon 9 (Heavy) rocket doesn't fly with ist 2nd stage into an low earth Orbit (parking Orbit) but instead directly launches to the transfer orbit and then lets the spacecraft complete the geostationary orbit (GEO) when it reaches the apogee. So when the 2nd stage is at the apogee or apoapsis or how it is called, the 2nd stage would almost need no thrust to shrink periapsis and reenter the atmosphere… and if the interstage is used as a heat shield it should be able to land it with some corrections near the launch site with a parachute...

[@matrixplace]

Great channel! Few days ago I was so far away from all space stuff, but watched just one SpaceX video and the madness began... Then I found your channel and just can't stop watching! You should definitely work for some space space company and fly at space! Cheers!

[@haroldinho9930]

Look where we are now. He’s going to the moon!

[@worawatli8952]

Why not build a removable heat shield at the top of second stage. When the payload deployed, dock the engine with the heatshield, then de-orbit with smaller engines or powerful rcs. When it entered atmosphere, release the heatshield and slow with engines or parachute.

[@facepalm7345]

can also add something to that, a removable extension to the second stage engine bell

[@rochelletarin6422]

I just want to thank you for making these informative videos! I've always wanted to learn about rockets but I didn't know where to start or it was confusing. You explain things so well! I've learned so much for you. :) Thank you!

[@j.jasonwentworth723]

There are three other possibilities that I can think of off the top of my head (and I'd wager that there are others as well): An inflatable conical heat shield, similar to NASA's IRVE test shield, would be lightweight and could completely enclose the second stage. (McDonnell Douglas engineer Philip Bono designed Saturn-derived [using up to 8 F-1 engines], SSTO--Single-Stage-To-Orbit--reusable rockets that used similar--but much larger--inflatable heat shields for ocean landings; the rocket wouldn't have gotten wet because of the way the heat shield would have been oriented in the water. Another option (which would permit rocket-braked landing of the second stage without needing a second set of landing engines) would be to use an aerospike rocket engine on the second stage. Aerospike engines have "inside-out" nozzles that automatically compensate for changes in the ambient atmospheric pressure, and they often utilize multiple combustor modules, which permits a wide throttle range (this is useful for landing a very light stage whose propellant tanks are mostly empty). They can also serve as "base (bottom)--first" heat shields (which can be actively cooled by circulating a relatively small amount of one propellant--usually the fuel--through them during re-entry and then venting it through the combustors). Philip Bono utilized aerospike engines in his many later designs for small to very large SSTO reusable spaceships. A recoverable & reusable second stage of this type is much easier to achieve than a SSTO ship, because SSTO vehicles--especially smaller ones; very large ones are not so difficult due to scaling effects--require very lightweight structures in order to achieve Earth orbit using just one stage (achieving SSTO on the Moon is easy, as the Apollo Lunar Modules demonstrated). Even the existing Falcon 9 second stages could (with relatively little modification) be left in orbit and used as space tugs, even to help support the establishment of a lunar base. Plus, the stages could serve as DIY habitat modules to begin such a base; landed on the Moon with temporary, removable landing gear (their Vacuum Merlin engines would permit soft landings there, with properly-timed burns), the stages could be laid down horizontal and covered with lunar regolith (for radiation protection and for regulating their internal temperature) to serve as pressurized housing and storage modules.

[@mluby7828]

J. Jason Wentworth since you mention it, I wonder if the OTHER aerospike (used on nosecones to keep bow shock farther from the vehicle) would be easier to deploy below the nozzle. Would avoid aerodynamic instability that using a high-drag IRVE opposite the heavy engine would cause.

[@andrewzhang1290]

I’m sure they’ve thought about. I very much doubt that they never thought about those

[@andrewbrown6653]

I like your thoughts, I am thinking along the same lines. They could put all of the second stages in orbit and transfer the fuel to one and then use the tanks to build on to the space station or use the material for other things. they could also collect all the expensive parts together and drop them all together behind a heat shield another mission brought up.

[@AndrewEddie]

What if you added a skirt to the second stage, possibly flared a little. Around the outside you have triangular wedges that fold over the engine to form the heat shield?

[@Keavon]

Really awesome video, Tim! From some of your earlier content, I thought your videos (while a pleasure to watch) were a bit below my level. I was very pleasantly surprised to learn so much from this one, and the production quality was also superb, which is hard to do because you had to stay in your spacesuit and make dozens of runs in KSP continuously interesting. Keep up the incredible and always-improving videos and posts!

[@EverydayAstronaut]

+Keavon Chambers thank you for the feedback and for appreciating the hard work!!! That means a lot! Glad I could help you figure out the concepts! Let me know if you have any other feedback and thanks for tuning in!

[@jewbacca97]

I love the concept of "percent error" when it comes to failure rates in Kerbal. I don't use Kerbal but it's a nice tool when thinking about your videos.

[@christianlibertarian5488]

OK, total nube question. Why not dump the tanks of the second stage, and just recover the engines? Heat shield around the expensive parts, ocean splashdown.

[@EverydayAstronaut]

+Christian Libertarian great newb question! The reentry part is still hard regardless and engines don't like salt water 😉

[@theatom7264]

One way they could do it is build a few small yet powerful enough engines into the body in pairs along the sides like the Dragon V2 Super Draco launch escape engines. It would keep engines away from the heat shield & safe from reentry.

[@DenGamleSkurk]

TheAtom For high efficiency in vacuum you need the engine bell to be large, which wouldn't be possible if the engines sit in the body on the side. Having one engine in the back of the rocket is more practical for this purpose. Still a cool idea though, and certainly would work in KSP :)

[@thermophile2106]

Oscar Gylling I think he is suggesting that the vacuum engine is used to deorbit the second stage, and a few small engines used to land it.

[@J-Rat871]

Everyday Astronaut I have wanted to go to Mars ever since I was a little kid but I'm still going to be too young to be on the first lunch which sucks because it's the year after I graduate from high school and I'm pretty sure I have to go to college first which will take up to four years so no way of me being on the first rocket

[@akashchavan6706]

Thanks everyday astronaut for Making such beautiful and informative videos!!!

[@EverydayAstronaut]

+Akash Chavan thank you for watching them! 😊

[@PObermanns]

I've been a fan of SpaceX for a long time, but I never understood the problems with second-stage recovery. This video was really informative - and a lot of fun to watch. I really learned a lot from it. Please keep posting.

[@jaredcrub9567]

When Tim said a little bit longer, I thought this would be 2 hours. I got to used to 1-1.5 hour videos

[@adrianmiller103]

Came for the spacex subbed for the spacesuit

[@EverydayAstronaut]

+Adrian Miller thank you!!! 🙏🙏🙏

[@aawqaq620]

@@EverydayAstronaut no problem

[@nothingisaac]

Bruh

[@ROBERTO1OOO]

I play KSP, I can confirm, really alone... :( I'd like to have a brief understanding of Cryogenic engines please :) Thanks and great vid

[@ROBERTO1OOO]

Thanks :)

[@Bozeman42]

Fuels such as liquid oxygen and liquid hydrogen boil away at normal temperatures.

[@avid0g]

Bozeman42, right. So the cold keeps them as liquids, so modest pressure, modest strength tanks.

[@magictoffee7066]

I have 1000 playing hours in Steam so...

[@abcqer555]

great video!! thank you for educating us and making it so accessible. very very interesting and helpful

[@Supadubya]

There's this thing called Skip Re-Entry you forget about. If the upper stage did not attempt to directly re-enter, but instead made several passes through the very edge of the atmosphere where re-entry heating is not substantial enough to cause damage, then the thermal issues after several such passes would be easier to manage... This requires more loiter-capacity on the upper stage and small adjustments to trajectory between passes to ensure re-entry on target, but the potential mass-savings from reduced re-entry heating are worth it... Either way, though, upper stage recovery is likely to be a challenge.

[@JFHeroux]

I was looking to comment mostly the same thing. While watching the video, I thought "Well, now he's going to mention atmospheric skimming, slow the stage down to the same velocity as the first stages, then put it down the same way." Drag is free, it's always there... and it's not like you are in any rush to get your second stage back because it is scheduled to launch tomorrow. I even think once the re-entry burn is done, you could probably use good old tech like a nice big chute and some airbags (how much would those weigh compared to struts, attitude thrusters and the electronics package to control all those systems? The second stage is much lighter than a first stage. I'm sure Musk already is working on something that will use a free form of energy to slow the thing down. You never want to put stuff in orbit (fuel or hardware) if there's another way to do the same thing. I am thinking the challenge could be in doing atmospheric braking with such an odd shaped thing as an unmodified second stage. Then again, if we can aero-brake interplanetary probes that are going faster than that and have the aerodynamics of a shopping cart, there has to be a way to skim a second stage as well. IMO, the tricky part is angle vs velocity... and also the time it is going to take for you to get the thing back down to a more manageable speed. If it is going to take 2 or 3 years, might as well not bother. But I suspect the stage can endure a decent amount of aerodynamic stress without braking up or being damaged...

[@jdg2209]

To make a video in a full astronaut outfit I give this guy credit... well done that man

[@EverydayAstronaut]

+jdg2209 hahaha thank you! The suit has gone all around the world with me... it's unfortunately become the bane of my existence 🤦‍♂️ check out my Instagram... that's what I'd done with it for the past 4 years - Instagram.com/everydayastronaut

[@letterslayer7814]

@@EverydayAstronaut isnt that where this channel pretty much started? i remember watching a video about this a while ago. ive got the exact same suit and i dont think it smells nearly as bad as yours (based on what youve said lol), its far from clean... im not sure why i even got it, probably just cool sorry for reviving a 2 year comment

[@raulcavalcante9193]

tim tood : bare me with this one it will be a little more techinical and a little bit longer video : 17 minutes me : oh, times have changed

[@aspuzling]

This is the first time I've come across one of your videos and I liked it, but I felt about as comfortable watching you trying to explain orbital dynamics in that spacesuit as you probably did wearing it.

[@EverydayAstronaut]

+aspuzling agreed. I hate the suit too haha but after four years of Instagram and now here it's the bane of my existence 😔 thanks for saying hi. I might not wear the helmet in the future for the whole video

[@aspuzling]

Everyday Astronaut I think that would be a great compromise 😀

[@weeliano]

This is an awesome channel! Great and detailed explanation on the challenges of recovering the 2nd stage!

[@EverydayAstronaut]

+weeliano thank you!

[@gameguy99ful]

Beautiful video, really good work, this channel means a lot to all of us. Why not design the second stages to be disassembled and built into space capsule type things, space transformers?

[@Nate7.75]

I would imagine the biggest deal would be cost on what your thinking. Making a modular second stage means putting money into R&D that creates stronger materials that could survive forces of launch and also separate and then go on to do more launches is a big ask. The only reason the shuttle was able to move materials around like that is because the whole housing of the shuttle was basically a big shield. Though if anyone was able to do it it would be spacex.

[@KaiHenningsen]

Because that would take the mechanisms for the transform in addition, which means even more weight.

[@rizendell]

what no solid boosters? If you don't see shock heating on the way up, you are not trying hard enough.

[@EverydayAstronaut]

+rizendell 😂😂😂

[@redsquirrelftw]

I actually managed to blow up a rocket that way, and it even crashed the game. lol. One of few instances where it's possible to have too many boosters.

[@ln5321]

Wait, it's possible to launch in KSP without seeing the shock heating effects?

[@johnrickard8512]

My Unicom 2 long range relay satellites don't cause shock heating on ascent.

[@justanotherintrovert1012]

I've made a completely automatic ARB satellite launcher that carries 2 small communications relay satellites into a steady orbit on 2 clicks, one at launch, and one at cutoff to deploy the satellites and activate 2 more SRBs yo deorbit the booster block to prevent space junk. It is very effective and cheap for launching multiple small satellites, and it pulls no shock heating on ascent, will upload craft file as soon as I can

[@flippdoubt8057]

Excellent presentation. Pace was pretty good there. Smooth editing too! Thanks for the wonderful information!

[@EverydayAstronaut]

+Flipp Doubt hey thanks so much! That means a lot! I’m continually trying to improve the videos, and thanks to feedback like this I’ll continue to hone it in.

[@flippdoubt8057]

Everyday Astronaut ...kewl, my son and I are subscribed & will continue to check in. I sure hope electromagnetism and anti-gravity R&D makes some significant jumps soon. With all of these companies so interested in space again, now would be the perfect time for such a leap in technology (as in Alcubierre Drive). Less war and more adventures!

[@mateusales]

Dude, I just want to say thank you for what you're doing. I've always been fascinated with space exploration and now thanks to you I have learned so much. Keep up the good work

[@EverydayAstronaut]

Thank you!!!! That means so much!!!!

[@justanotherintrovert1012]

a kerbal space program demonstration? *instant sub, like, and notificiations*

[@EverydayAstronaut]

Haha thank you 🙏

[@justanotherintrovert1012]

Fast response, I'm so HYPED for the launch, blasting space oddity the whole way to mars!

[@moesgymmom]

13:58 looks like New Sheperd

[@thePronto]

Cool vid - very informative. In the explanation of the challenge at the beginning, you forgot that the 2nd stage not only has to dissipate its own energy on re-entry, but also that which it gained from the first stage which, intuitively, seems nigh-on impossible.

[@ddegn]

You did a good job in 2017 but you do an *awesome* job in 2019. Keep up the good work.

[@KingBobXVI]

I once read about an idea (one of NASA's many sometimes ridiculous ideas) of getting the orange fuel tanks from the shuttle into orbit, and instead of just letting them burn up in the atmosphere, they'd collect them into a cluster that they could repurpose as a large space station. Do you know anything about that plan, or have any thoughts on doing similar for modern second-stages? I'd love to eventually see a retrofitted fuel-tank ringstation one day :P

[@EverydayAstronaut]

+KingBobXIV yes! I too heard about that idea. It's a super cool idea and I wish they tried it! Maybe one of the companies will try this out some day!

[@JFHeroux]

Sorry to barge in months later... but wouldn't handling stages potentially full of toxic and/or corrosive propellant be a problem you do not want to have to deal with in space?

[@alanbrown397]

Shuttle tanks only carried LH2 and LOX - they'd have been safe in space, modulo the outgassing issues. (Speaking of which, I wonder how big the gas cloud is around that roadster)

[@benzeamer5278]

Giant party balloon.

[@Zachmman1997]

Maybe if we made a new space station that operated as a rocket repair facility, we wouldn’t need to have second stages at all. Just keep anything going that fast in space. They could use bigger single stage boosters to transport fuel and materials into orbit. Anything that needs to go further into space can be launched into a higher orbit or geo, or whatever from that station

[@DavidRandall2020]

Wow, great. you worked so hard on that. Understood every word! Great job.

[@scooby990]

I’ve tweeted this to Elon before Keep second stages in orbit and use them as building blocks / modules of his own space station piece by piece. Then crew up and have this as a holiday destination (weddings in space) Or land these on the moon to build a base there.

[@canaldofred2366]

@@softb why?

[@canaldofred2366]

@@softb ok then

[@zapfanzapfan]

Elon has done a couple of "impossible" things already, I'm sure he'll figure out second stage recovery too :-)

[@zapfanzapfan]

Are you suggesting that Dear Leader doesn't design everything himself? How dare you! ;-)

[@MrTiti]

there is no point in returning the 2nd stage

[@mistertagnan]

MrTiti that's what they said about stage one

[@rolfbjorn9937]

Elon taught himself rocket science and he can apparently keep up with his engineers.

[@starcatcherksp1517]

Fun fact: The original reusable second stage design of SpaceX was for them to use hypergolic fuels. That way they can keep the heat shield at the bottom, while it'll be powered by Superdracos straped on the side.

[@gijsbesselink]

Just discovered this channel. That was awesome! Explaining the complex problem with KSP! I understand the issue now.

[@adrianmiller103]

New video idea: Your thought in SpaceX mars colonization rocket

[@EverydayAstronaut]

+Adrian Miller great idea! I'll wait until they update their plan this year and do a big healthy outline as we get more details 😊👍

[@catoomch]

Would it be possible to refuel the first stage after it has landed and send it back up again to retrieve the second stage? Without a payload the second time up, there'd be plenty of fuel left over to make a powered landing with both stages. Remotely recoupling the stages would be a hell of a challenge though.

[@EverydayAstronaut]

+catoomch a first stage alone would maybe just barely have enough delta v to put itself into orbit and would have not nearly enough delta v left over to land with itself let alone with the second stage attached... great thought though, just not nearly enough margins unfortunately

[@catoomch]

Thanks for your reply. Some very rough calculations here - please don't judge me. Could a Falcon 9 with a larger fuel tank be used as dedicated retrieve rocket? The dry weights of normal first and second stages are similar but in the retrieve rocket, the fully laden mass of the second stage is replaced by fuel (and some extra structural weight). The implies that the extra amount of fuel on the retrieve rocket (relative to a normal first stage) at the point where separation would usually occur will be equal to the mass of a laden second stage at separation, which means it can reach an orbiting second stage with extra fuel on board. Would this be enough to make a powered landing with both though?

[@catoomch]

Maybe this is what Elon had in mind all along. I was wondering why he opted for a pneumatic mechanism for stage separation rather than explosive bolts. The explosive bolts are lighter, more reliable, and pose no risk of damage to either stage. If he was intending the second stage to land under its own power, new bolts could be swapped in on landing. The only incentive I can think of for the increased complexity, weight and failure modes is to allow recoupling in orbit.

[@Supadubya]

catoomch what you are describing there is basically using an extended version of the upper stage as a dedicated fuel tanker to help recover the normal upper stages. And there is no reason, theoretically, that shouldn't work. If the tanker can reach orbit with more leftover fuel than it needs just to get itself back to the surface safely, it should be able to donate any excess to the other upper stage- and possibly enough to get them both back safely. However actually DOING that requires more practice working out the technical challenges of orbital transfer of cryogenic fuels...

[@catoomch]

The fuel transfer technology needs to be developed for the ITS tanker anyhow. This would be a good testbed for it. I'm talking about doing away with the second stage altogether, just one supersized first stage. The weight saved by not having a first stage should offset the extra structural and fuel weight needed.

[@ylhajee]

The idea you ended with is interesting, keeping your second stages in orbit to use their collective fuel later. I think they could also use these second stages and their leftover fuel to clean up space junk. They could grab onto a defunct satellite or similar and use their remaining fuel to deorbit it.

[@alithegeek]

6:09 That’s facts. Kerbal has indeed made it harder for me to maintain stable human relationships

[@yztefenbrianb.sanpablo666]

F

[@mistertagnan]

I'm going to Florida today to see the spaceX launch tomorrow, does anyone know how far the drone ship will be from the Apollo Saturn V center? And how visible will it be?

[@EverydayAstronaut]

+MrTagnan the drone ship will be about 200-400 miles away... unfortunately you will not get to see the landing. You can only witness landings for RTLS launches and this one is not. Wait a few days and you will see it come back into port though!

[@mistertagnan]

Everyday Astronaut alright. Thanks!

[@stef0262]

watch real life until rocket is out of sight, then watch the spaceX livestream on youtube.

[@mistertagnan]

Stef Morojna we did, it was shown on the screen at the Apollo Saturn V center

[@john.vandijk]

I noticed you talk about miles per hour, and kilometer per second. can't we just keep it all metric?

[@EverydayAstronaut]

+John van dijk with 70% of my viewership coming from the US, I want to make sure the numbers are relatable to everyone.

[@JFHeroux]

That is a really sad thing to agree with... but I know what you mean.

[@andrewzhang1290]

While I do think that using imperial is stupid, limiting quick information to one group isn’t cool. Sure, they can search it up, but it wouldn’t really make much difference if he put it in or not. I’m r/woooshing right

[@patata9502]

if him says 13.314 e-3 km/s then i quit he

[@Smoer1]

Fine, we'll let you do that if you just admit the metric system is the way to go for science;). @@EverydayAstronaut

[@CheetahNL]

How about putting heatshields on the landing gear? The landing gear would be opened outside the atmosphere. When entering it should provide lots of drag (and withstand the heat) while offering stability. It should be even possible to steer with them!

[@showalk]

Dude. You using your own music is what convinced me to subscribe lol, some good stuff there.

[@EverydayAstronaut]

+ShowALK32 that's awesome!!! Thank you!!! 🙏🙏🙏

[@dudezgamez550]

Anyone watching in 2020 Even on Jan. 1 2020?

[@KnowNot_Name]

DudezGamez so it’s late April now

[@nickgallo4935]

es

[@afrog2666]

Nah, I`m watching on a tv..

[@marielarodriguez194]

ThisIs Fine i’m watching in May

[@Abandonite1305]

Me but it is LATE MAY

[@slevelneves]

Why not use the atmosphere to slow you first? Get just inside the atmosphere, maybe 62km, and orbit 10 times or so. Then use rcs with the oberth effect to keep your periapsis at 65km. That will bring you in much slower.

[@rajivnarayan4237]

keeping a rocket near parallel with the surface in order to slow it down with a thinner atmosphere would literally use up all your booster fuel cos of the rotational torque of the engine. Don't quote me on this though I'm an electrical engineering student not aeronautical.

[@slevelneves]

EXTC yeah But, if you let the vehicle spin, there will be no need for any fuel spent unless correction altitude.

[@rajivnarayan4237]

Im not sure what you mean by 'let the vehicle spin', because if the vehicle spins on the horizontal axis its going to snap, Im assuming you are thinking of it spinning on the verticle axis in which case im not sure how you will do that without spending any fuel.

[@slevelneves]

EXTC yeah no. I mean let it move how it wants to move. Do not try to correct. As long as you aren't too far into the atmosphere, the vehicle will not break up.

[@KK-up3pq]

how about rotation for re entry stability?

[@TheNervousnation]

That was fun! ty for KSPing that for me subbed

[@LOLDEMOS]

That Kerbal try and error part was genius and epic. Good job!!

[@AngelArm1110]

That demonstration of the landing second stage was excellent!! I don't envy they guys Elon put on this project I tell you that. BTW, do you have heterochromia?

[@EverydayAstronaut]

+Robert Johnson yes I do!!! You're the first person to notice in my videos!!! I too don't envy those people. Haha

[@MrIcehole]

I didn't know what heterochromia is until now. :) Now I see it. A pitcher from the Nationals Max Scherzer has it too.

[@liskers]

When you reupload because you mix up tonnes with kg. rekt. I saw that, you got caught >:D

[@EverydayAstronaut]

+The Cough haha yeah!!!! My bad 🤦‍♂️

[@joeymurphy2464]

I hate to break it to ya, but at 15:06, you say the Space Shuttle was about 100 kg. Was this also meant to be tonnes?

[@EverydayAstronaut]

+Joey Murphy ahhhhhhhhhhh CRAP!!!!! Yes. I'll let the one slide!

[@stef0262]

Actually he saw the error, and put the effort into correcting it... idk why he would get "rekt" for it...

[@liskers]

You sir, are no fun, you don't get a very obvious joke :P

[@TricoliciSerghei]

Very nice video and informative. Thanks for your hard work!

[@EverydayAstronaut]

+Serghei Tricolici thank you!!!! Thanks for stopping by and saying hi!

[@jekster]

Super great production value. Keep up the good work Tim!

[@EverydayAstronaut]

+jekster thank you!!!! I'll be back at it soon with a new video asap!!!

[@mycinematics8948]

NASA want their binoculars back.

[@EverydayAstronaut]

+My Cinematics they're standard issue, that's for sure 😉

[@Xailow]

why not use the realism overhaul mod? and spaceY? and your mechJeb profile looks a little off. maybe it had to change due to the increased gravity. need to go play some ksp myself 😉

[@EverydayAstronaut]

+Alan John my computer is riding the struggle bus trying to screen capture and run Kerbal as is haha. Yeah I had to change the profile of mechjeb a lot to fulfill the illustration. 👍

[@mostevil0]

+Everyday Astronaut Copy out the whole KSP folder to a separate location. Have a separate Realified and Kerbalised installs. CKAN in the folder can manage the mods for you pretty well. Won't take too long to see if it'll run. Good video! Keep it up.

[@janelance7257]

Yes, rss/ro are more accurate than simply cranking the gravity

[@theatom7264]

I’ve seen images of a concept for a reusable second stage that resembles the lower half of the ITS spacecraft 2016 version only with a heat shield in place of where the Raptor engines would go at the bottom. I would imagine it could resemble something like that because the only way to make a second stage return to earth is to have the engines built in similar to how the Super Dracos are configured on the Dragon V2. It probably wont use landing legs for droneship or landing pad touchdowns because that would add complexity & weight so an ocean landing with parachutes would be the likely return/recovery method.

[@drabberfrog]

I'm the first like and reply this comment has had in a year

[@scharkalvin]

Awhile ago, I saw that SpaceX had come up with an interesting idea on how to recover the second stage. They modify the inter-stage adapter so instead of being thrown away, it opens up as three or four "flower peddles", remaining attached to the upper stage. In this position, now out of most of the atmosphere, it does not interfere with the operation of the second stage. After de-orbiting the second stage, the adapter closes up again, and additional flaps fold out to form a heat shield surrounding the engine. The second stage now comes down engine first. During the landing phase, the stage adapter opens up again, and forms the landing legs! The second stage engine fires to bring the stage down to the ground.

[@MrGustavier]

It's the very first video I watch of him, and after 3:45 min of watching, he already makes a big mistake : no it wouldn't take the same amount of fuel to decelerate as it took to accelerate, since the second stage has a full tank on initial injection burn, and an almost empty one for low orbit injection burn, and above all, IT DOESN'T HAVE THE PAYLOAD ANYMORE, how does he think the space X 1st stage does to go around after stage seperation ?

[@EverydayAstronaut]

+MrGustave1er I've addressed this in many different comments, I meant to say delta v and not fuel.

[@Supadubya]

Everyday Astronaut but the point is the same amount of fuel gets you a LOT more Delta-V when you don't have to deal with the payload. This is actually extremely inaccurate to try and simulate in stock KSP, though, because the stock fuel tanks have an insanely low mass-fraction compared to anything in real life, and the engines are much heavier for the thrust they provide. You need to run with RealFuels installed to get anything like an accurate image of upper stage recovery- if you do, you'll find your Delta-V went up by a LOT more when you reduced the payload- and would go up by even more still if you increased the size of the upper stage to take advantage of the reduced payload like you should (and lime SpaceX would realistically do if trying to design a reusable upper stage, and they decided they needed to down-rate the maximum allowed payload to enable reusability...)

[@nova9054]

in the boeing image why are the guys near the space plane in hazmat suits?

[@alphaadhito]

Nova Because they used toxic hydrazine fuel for the reaction control system

[@awuma]

It was exactly the same with the Shuttle.

[@prawnmikus]

They were in the pre-potato-growing stage of hydrazine handling.

[@oremooremo5075]

they are using highly toxic propellants

[@avid0g]

PS, the Super Draco engines use hydrazine.

[@coltonmccormack8978]

It's kind of hilarious seeing the ULA slide advertise 'Sports Car to the Stars' at 16:00. I wish I could have seen the marketing person's face when they saw what SpaceX was doing with their Falcon Heavy test a few months later.

[@johnjay7822]

One of the legendary cosmonaut spacesuit episodes lol. Tim, in a recent episode, you were still counting days since you last wore it. You're actually subconsciously counting down until the next day you don that uniform!! Surprise us!! May 27th would be a good day!!

[@unfundedopportunities7278]

Why did they drop the Saturn V entirely? They haven't had another vehicle that could carry as large of a payload since. It was proven technology and it launched Skylab, which was HUGE inside compared to the ISS. Astronauts could run on the walls! Imagine four Skylabs linked together. How many total smaller-payload launches did it take to construct the skinny ISS?

[@EverydayAstronaut]

+UnFunded Opportunities great question especially since it was actually cheaper per launch than the space shuttle!!!

[@simonm1447]

I think they thought space shuttle would be cheaper and they could have more launches, but they were wrong. At the end space shuttle was expensive and launched only a couple of times a year. In the aftermath it would have been a better choice to use Saturn 5 rockets after Apollo program.

[@Bobcat665]

The Shuttle was one step forwards, two steps back.

[@JehanKateli]

Sorry for the blasphemy, but wouldn't it be easier if they used... parachutes?

[@amosbatto3051]

Parachutes only work when you are slowing down close to landing. They would get burned up at high velocities and probably torn to shreds as well since they can' t handle the stress. Parachutes make it impossible to land precisely in a certain location, so they can't be used very easily on land, unless you have thousands of free acres. If you land in the ocean, then the salt water damages the engines.

[@ii8541]

haha.....HAHAHAHAHA. Sorry i couldn't stop laughing at that. a mere parachute can reduce speed with velocity so high that it could blow up the rocket. LMAO.

[@danieljensen2626]

I I The Apollo capsules all used parachutes so it's clearly not impossible to design ones that work. The range thing is a problem, but I think small drogue chutes deployed pretty much at the last minute could help with a propulsive landing.

[@SlamTF2]

The parachutes would be fairly heavy and have to be often replaced, and its systems replaced, with every flight. Not to mention it would require landing the second stage in the ocean due to parachutes being completely unable to make it have a soft enough landing on land, which would require refurbishing of the engines, body, etc. This is like how the Space Shuttle landed its boosters in the ocean, which took months of refurbishing and millions of dollars to reuse.

[@Zamolxes77]

It could use retro boosters for landing, the way Soyuz lands.

[@darklordofall6088]

The spacesuit is back :D (And yes I‘ve heard what you said in the stream. But I like it anyway)

[@minhnguyen690]

Thank you so much for the video with the explanation that I have been looking for.

[@GeovaniNogueira]

Well... I guess you have forgotten a very important asset that companies are using long before wings or retro propulsion -->>> PARACHUTES!! They are lightweight, occupy a reasonable small space and are relatively reliable. Definitely lighter than extra fuel + landing legs + wings. The effort to recover the 2nd stage on the ocean is significantly smaller than the first stage and can be done with a small ship and crew. SpaceX could possibly use some grid fins to guide the rocket and keep heat shield first orientation as well.

[@EverydayAstronaut]

+Geovani Nogueira parachutes can't survive reentry... the reentry part is the hard part!

[@GeovaniNogueira]

I know.. they would be used at the finals when the second stage reaches something around 20000 to 10000 ft, when the atmosphere is thicker and it's below supersonic speed! My guess it would work!! Just like a capsule...

[@loganhumphries4851]

Cant, parachutes are not able to accurately land so a water landing would be the only option. that being said the moment salt water touches the second stage it is completely ruined due to corrosion. Propulsive landing is the only option that supports musk's idea of rapid reusability.

[@dosmastrify]

Geovani Nogueira the whole point of landing on a platform rather than in the ocean is that sea water is corrosive and makes refurbishing much more expensive Plus have you ever seen something very very hot dropped in cold water ? it typically doesn't end well. you "guess" it would work but miss that people who do this for a living have determined it wont.

[@GeovaniNogueira]

One thing is for sure, as you said I'm guessing! To have certainty on this matter would be necessary design and simulate the whole thing... keeping guessing, I imagine that as our friend Everyday Astronaut has shown on his video, it's quite difficult to make it work with retro-propulsion landings, not to say almost impractical because would considerably reduce payload capabilities! About ocean landings you are all right, the ocean is very corrosive and can damage any metal it touches, if the engine has a good isolation on its main components, pipes, valves, compressor, electronics and combustion chamber, the only damaged part would be the cone. The 2nd stage body might become too damaged to be reused because of the reentrance stress forces anyway (guessing again!). But the only hot part that might touch the water would be the heat shield (which is disposable), then no problem with that! As the last time the engine would have been used would be at the deorbiting burn maneuver, at touchdown on ocean it most probably cool enough.

[@FreddyLuxe]

Subbed ! Keep up the great work man !

[@EverydayAstronaut]

+FreddyLuxe hey thank you!!!! I'm trying 😊👍 that means a lot!

[@1Play48]

I see that lego Saturn V in the background! I just finished mine and its awesome

[@jtveg]

Awesome video and simulation. Also cool spacesuit too. 😉👍

[@AdmiralPreparedness]

I proposed the same idea during the Apollo era. Keep it up there and use it later. Now, we can do much more such as launch a companion to dock and reconfigure the stage to come back as a plane. Transformer in disguise.

[@spsanders69]

I just started playing KSP about a month ago. So kicking myself for not getting it sooner. Such an amazing "game" but quite educational. Luckily, I can play on the laptop while wife and I watch TV. Plus she like playing her SIMS game so its all good. Thanks for the detailed breakdown on this concept. Enjoying the videos!

[@Orgruk]

Very informative, thanks!

[@stuartyoung4182]

...I honestly thought I'd subscribed ever since the first time you were on TMRO!!! Oh well, I did it tonight. Sorry it took so long! Great idea, using KSP to illustrate the HUGE difference between reusing first and second stages. You've got me thinking: heat shield; those hi-thrust RCS motors which use both fuel and oxidizer; air brakes; and chutes. I'll have to try it! My wife will be missing me this week... ;-)

[@nasedo1]

I have a simple solution - make second stage only partially reusable - we want to save the expensive liquid fuel engine, fuel pumps and electronics only, not the empty fuel tank. So put the reentry shield INSIDE the second stage, between the engine and the fuel tank. After payload separation deorbit the second stage, before it enters the atmosphere separate the empty fuel tank and rotate the remaining engine module reentry shield first. The engine module reenters the amosphere, which decelerates it to a safe speed, then it deploys three parachutes to hit the ground shield first.

[@monkeypants6764]

i love your channel its absolutly amazing!

[@jazzthrowout265]

I basically had a similar idea to ULA. I would however consider sending up a dedicated upper stage consisting only of fuel as payload after every four or five commercial launches in order to refuel all of the other upper stages quickly and at once. Otherwise you'll still end up having loads of empty upper stages orbiting around for nothing...

[@lornetontegode6986]

Move the heat shield to the engine end and eject it once it's served it purpose. Once the ship bas deployed the payload, and since speed is relative, disconnect from the heat shield at the payload end, use thrusters to flip the second stage around and install the shield over the engine end (similar to Apollo CM and LM spin around) . Keep the engine end (heavy end) entering first. Before landing dump the heat shield into the ocean.

[@AdrianFreerunUK]

at 3:45 you talked about the spacecraft needing the same amount of fuel to retro burn but thats not really the case, after the 2nd stage boosts up to LEO its significantly lighter due to having burned alot of its fuel already therefore lowering the delta V required for it go slow down therefore less fuel needing to be burnt. Great video, subbed :)

[@EverydayAstronaut]

+Dick Wittington you're absolutely right. I should have said DeltaV and not fuel and even so that's not quite accurate as you pointed out. Thanks for the sub!

[@ericmichell]

Thank you so much everyday astronaut for those interesting and insightful videos :-)

[@EverydayAstronaut]

+Eric Michell no problem!!! Thank you for stopping by and saying hi!

[@BiBaBeluBaB]

Crazy Idea: Let the second stage orbit, start a second rocket with fuel as payload and refuel the second stage. Use the refueling to slow down and land the rocket. Maybe Put several second stages together and bring them home at once?

[@Aluminator82]

Do you have a significant other, do you wanna keep the other, than don't play KSP. Wise words! Thats why I don't play KSP that much anymore. And thanks for the information about recovering second stage. I know you from TMRO. Fun to see your own channel. Subscribed!

[@EverydayAstronaut]

+Aluminator82 awesome!!!! Thanks for checking me out and saying hi!

[@antonnym214]

excellent video! Love the Kerbal sim you did. It's already a really exciting time, because now the USA doesn't have to depend on Russia to deliver crew to the ISS, and SpaceX will do the job much, much cheaper. All good wishes!

[@Statsy10]

Great video!

[@edwinross5494]

I assume SpaceX will store the heat shield between the first and second stages, then move it to the rear to cover the rocket engine during the first part of reentry. SpaceX is already working on automatic docking. As the heat shield does it job, it ablates and protects the rocket engine. When the speed drops sufficiently, pyrotechnics can eject the heat shield; whereupon, the rocket engine can be fired to land the second stage.

[@EverydayAstronaut]

+Edwin Ross a few problems. First off, there just simply is no margin with falcon vehicle for this which is why they’re pursuing all in on the BFR rocket. Second, moving a heat shield around is difficult and require a lot of weight. Third, the vacuum Merlin can not operate at sea level due to combustion instability of the large nozzle. But. I’m glad you’re thinking about this, but our assessment is pretty spot on for the fact that they’re going all in on BFR

[@lyf8]

Great explanation!! Thanks!!

[@thejetpuff966]

I think the main reason they dont recover it is because A. The second stage is super cheap anyway, B. the attatched engine is *very* vaccuum optimized, and likely wouldnt have enough thrust to land propulsively, which means more recovery hardware, and therefore more mass.

[@unitrader403]

Other possible Concepts i thought of: => Put the Heat Shield behind the Engine, but make it moveable with a Hinge or something. When the Stage is active move it to the side for Burns, for Reentry (Engine first) move them back. This way it could be stabilized without active Control. => (my preffered reentry concept from KSP): Put an Inflatable Heat Shield in front and lots of A.I.R.B.R.A.K.E.S. near the Engine (replacing the Engine Shroud with them) - using such a configuration i could do a Reentry with empty/light Fuel Tanks without active control and with Reaction Wheels + SAS it was even possible to reenter with a full medium MK3 Fuel tank directly behind the Engine and in front of that some empty/light other parts which usually is a very unstable configuration (its basically self-stabilizing if you are facing prograde) - admittedly had to spam Parachutes for the final descent though.. => use a classic heat shield in front, but also add an Inflatable Heat Shield which extends radially on the Rear to stabilize the Craft by moving most Drag to the Back. Works similiar to the previous Concept, but i think its more do-able. To fill the Heat Shield maybe add more Helium to the Tank, which is present to pressurize it anyway. (or use Heat-Shielded A.I.R.B.R.A.K.E.S. instead) => Regarding the un-usability of the Vac Engine in Atmosphere: afaik the only difference between Vac and Atmo Merlin Engines is the Length of the Engine Nozzle - the Vac Version is simply longer. So if you can get rid of some extra length of the Nozzle in-flight you can turn it into a Atmo Engine. not sure how though.. i guess Explosives are a bad idea because they might blow up through the operating temp of the Engine.. and mechanical means also have to survive that...

[@kartikbansal6439]

Couldn't have anticipated this video would be so informative, learned and enjoyed a lot. Also i have an idea, instead of wearing the orange suit, you can take some inspiration from spacex's suit (will definitely make you look more cooler :)

[@vanmaren962]

Whatever you did to get yourself noticed, keep it up. This video was excellent and speaks to your standard of quality.

[@EverydayAstronaut]

+vanmaren962 thank you very much! That means a lot! Im not exactly sure but I'm just gonna keep chugging away at videos 😊👍

[@brandonedwards1181]

KSP is very addicting , great video !

[@jhoblik]

Awesome video. I have one more solution, to try. Have inflatable heat shield that will deploy on orbit attach to leg, by moving leg to landing position.

[@iMeatbag]

Okay, one issue with this is that Kerbal doesn't correctly model the effect that happens from thrusting against the direction you're travelling through an atmosphere. SpaceX was the first time this was tested or proven and it's the reason the Falcon 9 can come back. It doesn't just slow itself down, the exhaust out the engine nozzles actually creates a barrier for the atmosphere to smash against before hitting the rocket and causing more friction.

[@cruiserchrisworldnetwork4141]

I've always wondered why SpaceX doesn't recover first stages thank you everyday astronaut you giving me the answer