Rocket Lab just announced they plan to try and recover their Electron rockets using a parachute and a helicopter… Yeah, seriously.
Well, the concept of air recovering a rocket definitely isn’t new, it actually goes all the way back to the Apollo era when NASA had some pretty nutty plans themselves. And they weren’t TOO crazy for considering air recovery, after all the Air Force started successfully recovering film from spy satellites in orbit as early as 1960!!!
But history hasn’t always been so kind to parachutes on rockets, because despite trying on the first two Falcon 9 missions, SpaceX failed to even get to the point where they deployed parachutes… So why does Rocket Lab think they’ll be able to do this? What’s different about their plans?
So today we’re going to dive into Rocket Lab’s plans for reusability including some deep dives on the challenges they face including the forces and velocities.
Then we’ll go into the history of air recovery, and compare Rocket Lab’s reusability plans to other space systems that utilize parachutes such as the space shuttle’s SRBs, the Falcon 9, SpaceX’s fairings, and even ULA’s similar plans they’re calling SMART reuse.
And with SpaceX now recovering fairings regularly with a parachute, are parachutes just all the rage now??? What’s going on? While we’re at it, we’ll talk a little about why SpaceX doesn’t try using helicopters instead of a boat to recover fairings.
I also got exclusive information from Rocket Lab and Peter Beck himself with some exciting additional details on just how exactly they hope to do this.
By the end of this video hopefully we’ll have a pretty good understanding if this wild plan is actually possible, or if it’ll be back to the drawing board for Rocket Lab.
Let’s get started.
On August 6th, 2019, Rocket Lab founder and CEO Peter Beck made an exciting announcement that their company is pursuing reuse of their wildly successful Electron Rocket at the Small Sat Conference in Utah.
The timing is perfect as SpaceX just announced the same week plans to do in-house ridesharing which could make the cost of launching a small satellite much cheaper.
Although the SpaceX announcement the day before Rocket Lab’s announcement obviously didn’t motivate Rocket Lab into making up a drastic reuse plan out of the blue, it certainly made publicly clear there’s competition knocking on Rocket Lab’s door.
Ok so first things first, let’s do a super quick overview of Rocket Lab’s Electron rocket, but if you want my deep dive on this super unique launch vehicle, I’ve already got you covered.
The Electron is a two-ish, kind of 3 stage orbital small sat launcher that’s capable of taking 225 kgs to Low Earth Orbit. It’s 17 meters tall, 1.2 meters wide, and the cost to launch a satellite is $5.7 million.
It’s a SUPER unique rocket in the fact that it’s the first rocket in the world to get to orbit using electric fuel pumps instead of a traditional turbo pump assembly that uses fuel to spin the pumps. It’s also the first orbital rocket to be fully carbon composite and they entirely 3D print their electric Rutherford engines.
It’s gone to orbit 6 times with only their first attempt not quite making it to orbit and their 8th rocket’s on the pad as we speak.
Ok now onto reusability, which I have to laugh about a little because Peter Beck has said over and over that there’s just not enough margin for a small launcher of this size to pursue reusability.
Peter even talked off camera with me about reusing the Electron after I interviewed him last year, to which he did have a little smirk, especially when I noted his love for helicopters. I was onto you Peter! So what the heck made him change his mind? I mean he even admitted defeat at the announcement saying he’ll have to eat his hat…
Let’s check out their plan and see what they came up with that seems to tantalizing…
On their upcoming 10th launch, we’ll see a pretty substantial block upgrade to the Electron. So hopefully by the end of 2019, we’ll see this rocket on the pad.
After stage separation, the first and second stage go their own ways. The second stage continues on to orbit and the first stage begins its coast up to its highest point after which it will begin falling back to Earth.
At this point, we know the drill here, the rocket will continue to pick up speed as it falls back to Earth until it begins atmospheric reentry.
Pretty quickly the rocket will begin experiencing serious reentry heating, just like how we see the Falcon 9 start to shoot sparks and see plasma build up as it experiences reentry.
The rocket will need to survive this reentry without doing any kind of propulsive slowdown. And that’s tricky when the plasma at these supersonic shock waves can be half the temperature of the sun!
But they have a small trick up their sleeve. At some point during reentry while still at supersonic velocities, the Electron will deploy a kind of supersonic decelerator or a drag device known as a ballute.
This helps increase the surface area of the vehicle and help slow it down quickly. Once in the lower atmosphere and at subsonic speeds, they’ll deploy a fully steerable parafoil.
And when watching this computer animation, you may think, uh that seems impossible. Well, check out this footage… does this look familiar? This footage is from PDG Aviation services who partnered with Airborne Systems and Lockheed Martin who successfully demonstrated this technology in 2017.
I’m sure it’s no coincidence since Lockheed Martin is an investor in Rocket Lab. It’s cool that we have legit tests of this system in place already, it makes this portion of recovery seem a lot less crazy.
Once the helicopter successfully grabs the rocket out of the air, it’ll lay it down on the back of the ship it took off from, and it looks like they’ll maybe employ some robots or small cranes or something to softly lay it down horizontally in a transportation cradle.
But here’s the funny thing, air recovery is actually a pretty familiar thing, after all, the U.S. Air Force began attempting recoveries of film from space in the 1950’s and was successful as early as 1960!
The program was called the Corona program and it’s honestly just plain crazy. So back in the day there weren’t digital cameras, gasp, so how the heck did they get high resolution film back down from space?
After all, let’s not forget, things in orbit are literally traveling 10 times faster than a bullet and need to survive hitting the atmosphere. This was no easy feat.
What the Air Force did was house the film in a canister that was basically a small reentry capsule. It would perform a quick deorbit burn and reenter. It had a heat shield that allowed it to survive reentry.
Once going slow enough, it kicked off its heat shield and deployed a parachute. Then a freaking airplane would swoop by with a giant hook on the back and snag it out of the sky. Even with a big, slow to maneuver plane, it actually would get about 4 tries before the capsule would splash down.
Cleverly, if they did miss all 4 times, the capsule had a salt plug at the base of it. This gave them about 2 days to recover the capsule before the salt plug would be eaten away by the ocean water and it would sink to the bottom of the ocean so no one, especially enemy forces, would accidentally recover it.
They actually did this with surprisingly great successes with a total successful recovery rate of recovery of nearly 75%!
And maybe seeing this great success led to some pretty wild plans for NASA to try and air capture the first stage of a Saturn V… aaa yup, you heard me right.
The Saturn V, the largest rocket ever successfully flown, you know, the 10 meter wide, 110 meter tall rocket that took humans to the moon… yeah NASA looked into trying to snag THAT out of the sky with a helicopter that would take up an entire city block!
Hiller aircraft proposed building a helicopter with a rotor diameter of over 120 meters that would have a useful payload of nearly 250 metric tons. The concept was to recover the first stage which was still a whopping 42 meters tall and 10 meters wide, but even empty it weighed 130 metric tons!
This giant helicopter would’ve been powered by jet engines on the tips of the rotors, 6 in total to spin the tips up to nearly the speed of sound, rotating once every second. As nutty as the Apollo program was, this would’ve been by far the most nutty thing ever built.
As we know, this program never left the drawing board, but it’s definitely not the last time we’d see recovery via parachutes.
And of course, let’s not forget about the Space Shuttle which ditched its solid rocket boosters at only about two minutes into flight.
They then did something very similar to what Rocket Lab is planning to do, which is coast up to their highest point, reenter the atmosphere and pull a parachute. Only as you may know, the SRBs were allowed to splash down due to their simple nature.
The next example of trying to recover a booster with a parachute was SpaceX’s attempts. SpaceX originally planned to recover their Falcon 1 and their Falcon 9 with parachutes. That’s right, you might not know that the first two flights of the Falcon 9 actually had parachutes packed up in the interstage of the rocket.
After the second attempt SpaceX realized they weren’t even getting to the point where they could deploy the chutes because the boosters weren’t surviving reentry, and therefore there wasn’t really anything for the parachutes to even recover.
Not to mention they hadn’t really solved how the booster would’ve survived a splash down, but that was probably the next step after successfully deploying the chutes. As we know, the program took a different turn.
The next one I want to talk about is also with SpaceX because we’re all of a sudden seeing them successfully recover their fairings using parachutes! As of the making of this video, they’ve caught two fairings in a row on a boat, named Go Ms. Tree formerly known as Mr. Steven.
Now this might be confusing to some people, how can the fairings survive reentry without propulsively reentering but not the booster? Well it mostly comes down to the surface area of a fairing and its lightweight nature.
This allows it to slow itself down in the upper atmosphere much more effectively than an aerodynamic and much heavier booster. Think of it like a piece of paper vs a pencil. Obviously the piece of paper has much more surface area and the atmosphere has a much greater effect on its velocity.
The fairing orients itself in the very upper atmosphere using some cold gas thrusters so the curvy end is down, then it basically surfs back into the atmosphere, bleeding off speed along the way.
Once it’s in the lower atmosphere it deploys a steerable parafoil and maintains a GPS heading and path. Then the ship autonomously follows that same heading, steers up underneath it and catches it! Now that SpaceX has caught two fairing halves in a row, this method is seeming more and more worth while!
As a matter of fact, SpaceX actually doubled down and bought a second boat named “Go Ms. Chief” so they can catch both fairing halves.
Please welcome the newest member of the @SpaceXFleet, Ms Chief. Soon, she’ll be outfitted with arms and a net so SpaceX can begin catching BOTH fairing halves. Just another step in making access to space cheaper. pic.twitter.com/W3npOuNV1e
— Stephen Marr (@spacecoast_stve) August 10, 2019
And lastly I want to talk about United Launch Alliance’s SMART reuse system for their upcoming Vulcan rocket. The Vulcan rocket is the replacement to ULA’s Atlas V and Delta IV!
It uses two methane powered BE-4 engines built by Blue Origin, who will also use 7 of those engines to power their New Glenn rocket.
The Vulcan plans to start flying in 2021 and eventually they hope to start trying to recover the engines from the vehicle, which they announcement way back in 2015.
Their plan is to jettison the whole thrust structure with the engines from the tank of the vehicle. Then they’ll deploy an inflatable heat shield to make sure that the dense and heavy engines can survive reentry and maintain proper orientation.
Then, much like Rocket Lab’s plans, they deploy a parachute once in the lower atmosphere and then they’ll use a helicopter to swoop it up out of the air before they splash down.
So now in order to get a sense of what Rocket Lab is attempting to do, let’s actually put up the five different recoveries we just talked about and check out their trajectories and see if we can figure out what Electron has to face.
For this I reached out to my friend Declan Murphy who made FlightClub.io. With this incredible website, we were able to plot all of this stuff.
And his simulations are SHOCKINGLY accurate. I’m so impressed by his work which is why I support him on Patreon, and I think you should consider doing the same as a thanks for this valuable information he helps provide!
So here we have the profile of the space shuttle SRBs from STS-129 to be exact in green, a pretty aggressive but recoverable GTO flight profile from the first stage of the Falcon 9 in blue including the fairing profile in white.
Then we’ve got a pretty standard Electron first stage profile in red, and lastly we’ve got an approximate estimate for the Vulcan rocket in yellow.
Now I want to point out this is an approximate profile originally based on an Atlas V 551 and since we don’t have any flight data on Vulcan yet, we just took this as a good starting point.
Based on some information from Tory Bruno’s reply to me on twitter, the Vulcan will have even longer burn times than the Atlas V!
So let’s figure an Atlas V 551 will be fairly similar to an average Vulcan GTO mission considering they share the same upper stage.
And one last final reminder, these numbers are all approximate as they can vary greatly from mission to mission, but they’re pretty good representations of what we might expect from each vehicle.
So first things first, all of these systems are suborbital and they still have upper stages that continue on to orbit.
But now let’s plot their peak velocities, their altitudes and their down range distances.
Let’s start off with their altitudes. The Space Shuttle SRBs apogee was only about 65 km in altitude, next the Falcon 9’s first stage rarely gets above 120 km, then we have the fairing which gets a little higher at around 140 km, followed by Electron’s first stage which gets up to around 170 km and lastly we have the Vulcan’s first stage which will get to almost 250 km at its apogee.
Next let’s look at their downrange distance, or approximately how far downrange these things will end up. The space shuttle SRBs again are first at only about 285 km downrange, followed by both the Electron and Falcon 9 first stages at right around 620 km downrange, then the F9 fairing at around 740 km, and lastly the Vulcan first stage which will land around 3,600 km down range!
Lastly, and most importantly let’s look at their peak velocities. The Space Shuttle SRBs were of course the slowest at around 5,000 km/h, followed by the Electron booster at around 7,500 km/h, then the Falcon 9 at around 8,000 km/h, then the F9 fairing at 8,500 km/h and lastly the Vulcan booster which will almost reach an astonishing 20,000 km/h!!!
And the peak velocity is really what’s an incredibly important factor here.
That’s because reentry heat’s relation to speed is CUBED. Not squared, but CUBED. That means if something is reentering twice as fast the heat it experiences goes up EIGHT TIMES.
This is the major factor that makes reentry so difficult and it directly correlates to the vehicle’s velocity. But we have very different systems and very different reasons for each of these recovery methods.
For instance the space shuttle’s SRBs didn’t need any kind of propulsive reentry, or air recovery because they were essentially just big giant metal tubes made out of 13mm thick steel.
And since they didn’t get as high or as fast as the others, it experienced less heating on reentry and because it’s not a liquid fueled rocket, NASA had little qualms with it splashing down. That being said, it wound up being about the same cost to fish these out of the ocean and refurbish them as it did to just make new ones.
Ok, now let’s look at the Falcon 9. Why couldn’t it survive reentry? Well, that’s actually a very valid concern. But I think another big factor wasn’t surviving reentry, perhaps they could’ve managed that more passively if they wanted to, but SpaceX knew they had a bigger problem lying just after reentry.
Assuming the booster survived reentry, if SpaceX were to rely on parachutes, they would be subjecting the rocket to splashing down, which I can only imagine they really wanted to avoid.
And it’s not like a rocket the size of a 15 story building that weighs over 20 metric tonnes empty would really be a very easy option for air recovery.
But with a vehicle the size of the Falcon 9, SpaceX likely has a lot more leeway in their payload capacity and could have some flexibility in mission profiles where they wouldn’t need every drop of performance out of the first stage and realized they could utilize propulsive reentry and landings effectively on a number of missions.
Now another fun question might be why isn’t SpaceX doing air recovery of their fairings? I mean after all, the fairings are much lighter weight than a Falcon 9 booster, and probably close to the same weight as the Electron booster… wouldn’t it be easy for them to grab a fairing out of the sky?
Well, grabbing it likely would be just as feasible, but controlling once they catch it, might not be possible or safe. Don’t forget, these fairings can literally fit a city bus inside them! It’s so easy to forget just how enormous they are.
And because of their low weight and large surface area, they would essentially act like a giant sail themselves, posing a pretty big risk to whatever aircraft would be trying to maneuver it back down to the recovery vessel.
Imagine the rotor wash of a helicopter hitting that giant fairing, it’d go NUTS, or imagine a plane which has to go pretty quickly to you know, fly, dragging a giant sail behind it.
Probably just not a good idea. And besides, the boat works and most certainly is cheaper to operate than a boat and a helicopter.
Now it’s likely that both ULA’s SMART reuse and Rocket Lab came to the same conclusion. They think they can safely and reliably swoop these things out of the sky before they hit the water.
But, one note… because of the long burn times needed by the first stage of the Vulcan, the first stage will be very far down range and going very very fast. So fast that the Vulcan will likely see around 60 times more heating on reentry than the Space Shuttle’s SRBs. Let’s hope that inflatable heat shield does the job!
But the main takeaway here is the Electron is such a small rocket, it’s just the right size for air recovery to actually be reasonable. I mean sure, bigger rockets could be feasible, but you might find yourself having to also manufacture the world’s largest helicopter in the meantime.
No wonder Peter Beck kept calling it “the wall”. Considering the Electron will likely reach similar velocities as a Falcon 9, it’s amazing they’re going to attempt to survive without a propulsive reentry.
So how the heck are they ACTUALLY going to do this? Well there’s one thing they can’t get around, and that’s extra weight. There will be additional weight added to the first stage of the Electron in order to make it recoverable.
But according to an email I received from Peter Beck, “We have some overall performance improvements to the whole rocket that will hopefully negate the extra mass of the s1 systems. The good news is that s1 mass has a much lower effect than any other stage on payload”
So luckily the first stage takes a lot less of a performance hit than an upperstage. The general rule of thumb is the first stage only takes about a 4:1 payload penalty kg for kg. That is, if you were to add say 400 kg worth of recovery hardware to the first stage, you’d only lose 100 kg of useable payload capability.
There’ll for sure be extra weight for the parachute and ballute and also likely additional supporting structures that handle the tensile loads that are exactly opposite of the normal compressive loads a booster experiences.
But not only has Rocket Lab had several flights to really dial in the performance of their rocket, they’re also literally riding a technology that is prone to upgrades, the Lithium Ion battery.
Lithium Ion batteries are one of the most competitive industries in the world, and best of all, Rocket Lab reaps the benefits of that competition. Everyone is working feverishly on making a better battery since batteries are officially in absolutely everything.
From where I’m sitting right now, just in this room alone I can count at least 5 devices which all run on lithium Ion batteries and I’m not even counting the dozens of camera batteries I have for various cameras.
Now Rocket Lab mentioned massive upgrades to their Electron, and it might be safe to assume they unlocked a little extra potential via battery upgrades and additional tuning, but that’s yet to be confirmed.
Another fun thing to remember is due to their electric pumps the Electron can actually run to tank depletion, something a turbopump engine can’t do safely. This means Rocket Lab can safely push the first stage all the way to MECO and assuming their reentry systems hold up, they’ll have a promising recovery.
But there apparently won’t need to be any additional weight for additional thermal protective systems, because according to Peter Beck, they’ll use the standard system they already have on board as they have good experience of how it behaves in a heat flow.
According to Peter Beck, “At the base of the Stage 1 there’s already a chunky heat shield and flex boots to deal with the base flow heating from the engines. Multiple engines create some recirculating flow regimes that they have to deal with anyway.”
They also will need to add some type of control system to make sure the stage maintains a proper and controlled orientation throughout reentry. This may be some cold gas thrusters or even small aero features.
Peter Beck didn’t comment on how exactly they’ll control it, but he did say there will be some control systems because they have a narrow corridor to make it work.
I assume that means they have a very precise reentry trajectory and perfect angles of attack that seem to be conducive for a successful reentry.
But he did mention they have some “supersonic decel devices to scrub velocity as best we can” so we know they have the ballute, but I’m thinking they might also have some other tricks up their sleeves to scrub off velocity at supersonic speeds, maybe even air brakes on the interstage or near the base.
I’m not going to read into the computer animation too much, but I can’t help but think these shiny bits on the interstage and near the bottom look quite different than their production interstages and thrust section.
If Kerbal Space Program has taught me anything, airbrakes really can help scrub off a lot of speed and they can also help to maintain orientation.
But for my own personal speculation, I definitely think surviving reentry without any kind of propulsive burn is going to be impressive. I’m certainly not going to doubt that they’ve run the numbers and feel confident enough in their system to survive, I’m just stating that this is very very difficult.
I asked why I they thought the Electron will survive when other vehicles have failed to do so and Peter Beck replied:
“Our vehicle is very different. The mass vs drag of the stage is different, the stiffness, the materials and the size. We may end up in the same place as previous efforts, but while we see a feasible path we will go after it.”
And you might be asking, why don’t they just do a propulsive entry? Well, the Electron is already absolutely pushing the limits on its payload capacity and they’re running the tanks to depletion to just barely get those 225 kg into orbit.
That’s not a lot of payload capacity in the first place and Rocket Lab has to get clever like ditching batteries and using carbon fiber tanks just to eek into orbit to begin with. So now that they’ve added additional kit for recovery, they most certainly won’t have even a drop of fuel to use for propulsive reentry.
As Peter Beck said in the announcement, if they start adding margin for propulsive entry and especially propulsive landing, they quickly get into medium sized launch vehicles, and this vehicle’s sole purpose is to have as many dedicated launches for small sats as physically possible.
Seeing how clever Rocket Lab has been to date, I have a lot of faith in their engineering. They don’t tend to announce stuff prematurely and I’m guessing they’re pretty confident that this will be more successful than it might seem on paper.
After all, they’ve actually gathered data on the last two missions, and this upcoming mission number 8 will have basically a black box named “Brutus” that will record all 15,000 channels of data in really high fidelity to further compare their models are accurate with real life.
Even if they recover and reuse boosters once, they’ll essentially double their output of potential launches and eventually they might potentially be able to bring their costs down even more!
So what do you think? Do you think the Electron will survive the wall? Do you think they’ll nail it on their first try? Think they’ll have to resort to propulsive reentry? Let me know your thoughts and questions in the comments below.
And let me know if there’s any other questions you have about Rocket Lab, recovery of rockets, or just spaceflight in general! I’ve got tons and tons more videos coming out, I’m cranking them out as quickly as possible, so stay tuned!