- Hi, it's me, Tim Dodd, the everyday astronaut. I'm here at Kennedy Space
Center Visitor Complex in their gorgeous rocket garden. I mean, look at this place. How awesome is this to talk to you guys about rocket pollution? Because there's no arguing that rockets aren't incredible pieces of machinery. I mean, forget the fact
that they're currently really the only way we have to put anything meaningful into orbit. But seeing and hearing a rocket launch is simply an unforgettable experience. We are in this. We are doing this! Yes! But as awesome as those
flames and sounds are, what's not awesome is when you stop and think about just how much
a single rocket pollutes. I mean, some I find it ironic
that an organization like NASA who studies our atmosphere is okay with rockets polluting it so much. Or isn't it weird that Elon Musk, the same person who's pushing
for sustainable energy so much with Tesla also
owns a rocket company that runs basically
entirely on fossil fuels. And let's not forget about Jeff Bezos, who literally just pledged $10 billion to help combat climate change
is also simultaneously working on a huge rocket that's almost the size of the Saturn V moon rocket that he's going to be
launching all the time. I mean, isn't this all just
a little bit hypocritical? So today, we're going to do
a deep dive into all this. We're going to figure
out just how much of what actually comes out of the
flamey end of a rocket. Then we'll look at how
much different fuels and different engines
changes that equation. And then we're going to compare rockets to other forms of transportation,
and other industries. And we'll even figure
out what would happen if SpaceX's proposed
Starship point to point transportation system here on Earth would actually replace jet liners. Would that be an improvement or a massive step backwards
as far as emissions go? But that's not the only
environmental impact rockets have, is it? I mean, what happens when a
rocket crashes into the ocean or into the ground? That can't be good, right? Or what about space debris? I mean, we're hooking so
much stuff up into orbit. Shouldn't we be talking about that too? Well, those will be upcoming video topics. But for today, we're
just going to be focusing on the environmental
impact it has on our air. So by the end of this video, hopefully, we'll have a really healthy understanding of the environmental impact that rockets have on our atmosphere. We're gonna figure out whether
or not launching rockets is a really reckless thing to be doing. Or if in the grand scheme of things, it's not that big of a deal. And lastly, we'll look at the things that the aerospace industry is doing today to make rockets better for the future. Let's get started. (bright music)
- Three, two one. (upbeat music) - This is a question I get
asked about all the time. And quite frankly, it's
a fantastic question. And there's actually some
other articles out there but they can kind of tend to be misleading and they just barely skim the surface. So they don't really have the
context or the hard numbers of all of the stuff to really
answer the question, right? So I figure it's time we get
down to the bottom of this and finally really figure
out how big of a deal the emission of rocket
launches actually are. So I've spent about five
months really trying to gather as much information as I can. I even ended up hiring a
researcher, Lisa Stojafoski to help me do some additional research. While I continue to
study up on this subject, because, I mean, as far away as I am
from a rocket scientist, I'm even further away from
being a climate scientist. But now I've spoken with experts. I've read research paper
after research paper, and I'm constantly having
to update the stupid script, because I keep learning things
just about every single day, because this is a really, really
deep, complicated, nuanced, but actually a really interesting topic. So stick around to the end because I promise this is
actually quite fascinating. But right off the bat,
let me address one thing. I'm no doubt opening up a massive can of internet worms here. But hear me out. We're just gonna go
over a bunch of numbers and compare them to some other numbers so that you can form your
own opinion on the matter. I know somehow climate
change and pollution has kind of become a
political topic, I guess. It honestly doesn't really
make any sense to me. But regardless of what
you think about words like climate change,
greenhouse gases, or CO2, let's all agree we probably
don't wanna live on a world that's terribly polluted
and we physically can't live on a world that's uninhabitable. So with that in mind, please
please just keep the comments section clear of politics and
pointless internet arguments over climate change and
all that kind of stuff and just look at the raw
numbers here with me. And we're gonna use that
to shape our knowledge on the impact that rockets
have on our planet. And this video is really
mostly just going to focus on what actually comes out of
the flamey end of a rocket. And we'll kind of gloss over
manufacturing, transport, ground operations et cetera,
et cetera, et cetera. Not to ignore them and act
like it doesn't matter, but because that would kind of turn an already insanely long video
into the longest video ever. And a lot of those
things are not exclusive to rockets either. This video will be a roller
coaster of good and bad. You'll be like, oh, that's not that bad. But oh, that's really bad back to. I guess it's actually not that
big of a deal, over and over. But there's so many little side notes and interesting tidbits in this video. So we'll be going to tangent town. Sorry, not sorry. But because this video has
so many topics and tangents, here's the timestamps for those. There's also some quick
links and an article version that has some extra resources, methodology and the numbers for you to check out in the description as well. So get a drink, a notepad and
your periodic tables ready 'cause we have lots of
science to talk about. (bright upbeat music) So to start off, let's
make one thing clear. Humans won't be abandoning
traditional rockets anytime too soon. There just simply isn't another form of propulsion feasible with
our current technology. As much as I want to believe
in anti gravity warp drive magnetic super thrusters
that my comment section seems to be constantly telling me about. Until the lizard overlords bless us with access to those things, rockets are really all we've got. After all, rockets are simply
machines whose sole purpose is to extract as much kinetic energy out of chemical bonds as possible. And just look at a rocket launch. There's an unbelievable
amount of energy involved. Okay, right off the bat, we have something to
take into consideration. Notice when a rocket is taking off, there's a giant white cloud of
smoke that it leaves behind. That looks pretty nasty, right? And then watch as the rocket ascends, the cloud doesn't actually follow it. The exhaust will end up looking much more clear very quickly. What's going on here? Well, luckily that giant
white cloud of smoke isn't actually smoke at all. It's almost entirely a
giant cloud of steam. And that's because many
rockets and their launch pads utilize a water deluge/sound
suppression system to not only keep the launch pad intact, but it also dampens the
sound energy of the rocket. So it doesn't actually damage itself. By dumping over a million liters of water during that initial launch sequence, most of that water is vaporized
and it turns it into steam. And in doing so, it absorbs
a lot of energy with it. So you'll notice that many
rockets when they clear the pad, they no longer have that thick cloud of smoke following them. Although some of them still do. But more on that in a second. So next, I'm going to
list basically everything that can come out of the
flamey end of a rocket. We'll then organize and
classify those things. Then we'll show which
rocket engines produce what. And wrap it all up by
showing how much of what each vehicle and each system produce based on their engines and
their size and their fuels. Rockets can produce many
different emissions. But here's the list of usual suspects. You got CO2, water vapor,
carbon soot, carbon monoxide, which will almost always bond
and become carbon dioxide, nitrous oxide, chlorine,
alumina and sulfur compounds. Now, I should note that I
accidentally kept saying nitrous oxides instead
of oxides of nitrogen or nitrogen oxides. So just know if you hear
me say nitrous oxides, I kind of actually mean
the more generic term which is oxides of nitrogen. So just keep that in mind. There's many other trace gases, but they're literally insignificant. You can barely even measure them compared to these main ones. So we'll really just focus on these primary ones going forward instead of getting into the weeds with all these little tiny trace gases. Out of these main gases, the United States' Environmental
Protection Agency or EPA, considers nitrogen oxides, sulfur oxides and carbon monoxides as pollutants. Think of most of these things like the bad stuff that comes out of cars or like smog in a big city. Chlorine, alumina and nitrous oxides can actually destroy ozone and are therefore considered
ozone depleting substances, or ODS, and have been
very heavily monitored and restricted since 1996. You may have heard that term punch a hole in the ozone layer or something like that. It's that but that's just
kind of a wrong term for it 'cause it's not a layer and you don't really punch holes in it. CO2, nitrogen oxides, soot and water vapor are greenhouse gases, or they act like one
since soot isn't a gas. These are just elements
that absorb more heat than the current equilibrium
of our atmosphere. This is called radiative forcing. And we'll get more into
that a little bit later. But simply put, if there's more of these
substances in our atmosphere, our atmosphere will then have
the ability to trap more heat from the sun. It's just really that simple. Chlorine is actually considered
a hazardous air pollutant by the EPA. And sulfuric compounds and nitrogen oxides can actually cause acid rain. And that's really bad
for marine life and trees and well, I guess pretty
much anything living. So now which rocket fuels
produce what emissions? Let's compare RP-1, hydrogen, methane, solid rocket fuel and even
hydrazine based hypergolic fuels. Going over these will pretty much cover the vast majority of rockets and which fuels they actually use. So let's start off with the
dirtiest of rocket pollution. And that's solid rocket boosters. You'll typically see solid rocket boosters on the first stage of rockets where high thrust really matters. Perhaps the most famous
solid rocket boosters were those two giant
white boosters on the side of the space shuttle. They produced over 85% of the space shuttle's thrust at takeoff. But there's also two massive and mighty solid rocket
boosters on ESA's Ariane V. Those huge solid rocket
boosters cause the rocket to leap off the pad in a real hurry. You also see SRBs attached
to the first stage of many rockets for a little extra oomph. Solid rocket boosters
are typically composed of hydrochloric acid ammonium perchlorates and the salt of perchloric
acid and ammonia which are powerful oxidizers. And then there's also
aluminum or magnesium powder. These are then held together by a binder, by a bunch of words I know
I'm not gonna pronounce anywhere near right. These are usually hydroxyl
terminated polybutadiene, known as HTPB or polybutadiene
acrylopitrile known as PBAN, which makes the propellant
into a rubbery like mixture. Please don't make fun of me too much. I'm a terrible pronunciater. This means they emit
primarily aluminum oxide, soot or black carbon,
CO2, hydrogen chloride, nitrogen oxides, hydrogen
and a few other trace gases. Since we mentioned the space shuttle, let's take a look at its main engines. The RS-25, which ran on hydrogen, or more specifically
hydrogen and liquid oxygen or otherwise known as hydrolox. The Delta IV, the Ariane
V center core engine and the centaur upper
stage also run on hydrogen. Hydrogen is perhaps the
cleanest burning fuel. When you burn hydrogen with oxygen, you literally just get water vapor. But there is a trace amount
of nitrous oxides, aka NOx, while the vehicle's in
the lower atmosphere otherwise known as the troposphere as an after burning
effect of the hot flame coming in contact with our air. Because literally all
rocket engines that are hot, which is pretty much all
of them, will do this to a certain degree
when in our troposphere, which is primarily composed of nitrogen. Next, let's look at a
very common propellant, which has been pretty prevalent throughout the entire
history of spaceflight and this is RP-1. But again, it's mixed with liquid oxygen, so it's known as kerolox. The first stage of the Saturn V used RP-1 as well as the Falcon 9 and Falcon Heavy. The core stage of the Atlas V, Soyuz and Rocket Lab's Electron
to name just a small few. RP-1 is basically just a
highly refined jet fuel which in itself is just a
highly refined kerosene. When burnt, RP-1 will
produce carbon dioxide, water vapor, nitrous oxide,
carbon soot, carbon monoxide, which again will mostly become CO2 and a little bit of sulfur compounds. The exhaust is kind of nasty, but it's not really all that different from what a normal internal
combustion car engine produces. Speaking of nasty, let's take a look at hypergolic fuels. Hypergolic fuels are those
that will spontaneously combust when the fuel and the
oxidizer come in contact with each other. This helps make rocket
engines extremely reliable as you simplify the ignition sequence. They're also very stable
at room temperatures, which means you can
actually fuel up a rocket and it will happily sit
there ready to launch for long periods of time, which made hypergolic
fuels a perfect choice for Titan missiles and other missiles that need to be able to
launch quite literally at the push of a button. But hypergolic fuels are also
used on the Proton rocket, the abort motors for
SpaceX's Crew Dragon Capsule and Boeing's Starliner
and the Space Shuttle's Orbital Maneuvering system as well. It's also very common in
reaction control systems and long duration coast stages for all of these same
reasons; being simple, reliable and stable. But hypergolic fuels include hydrazine or one of its relatives that I know I'm not going to pronounce the
name anywhere near rightly, like monomethylhydrazine or
unsymmetrical dimethylhydrazine, which are extremely toxic. Breathe too much of either of those in and you'll likely not
live to tell about it. - [Announcer] Lung tissue is burned, blisters form and the
resulting moisture accumulation causes us fixation. - It's mostly the biggest concern if you have unburned
hydrazine or spill something while you're trying to handle it. So perhaps handling the
fuel is a bigger concern than actually burning it. However, when burned
hypergolics are pretty similar to RP-1, producing mostly
CO2, water vapor, soot, sulfur containing compounds and a bit more nitrogen
oxides than other fuels since nitrogen is a compound
found in the oxidizer, which is usually nitrogen tetroxide. Lastly, let's talk about the
new kid on the block, methane, or when burnt with
liquid oxygen, methalox. Three of the newest rockets coming online in the next couple years
will be running on methane. That SpaceX's Starship, Blue Origin's new Glenn's first stage and ULA's Vulcan's first stage as well. Methane is probably the next
most clean after hydrogen, which makes sense since it's
such a similar compound. So when it's burnt, methane just becomes CO2 and water vapor and again, along with a
little bit of nitrous oxides. Now this might be contrary
to what you've heard. I mean, it's a common thing
to talk about how belching or farts of cows is just methane and how bad of a greenhouse gas that is. Well, that's true. But that's because it's unburned. Methane in the atmosphere is a real powerful greenhouse gas. So it's actually better
if it's been burned and split up into CO2 and H2O. Well, at least as far
as greenhouse gases go. (bright upbeat music) So let's see some real data
on some real world rockets. For this, let's look
at a variety of rockets with a variety of different fuels. And we'll actually take a
look at how much of what each rocket produces. Let's compare the Titan
II rocket which ran on hypergolic propellants, the Soyuz FG, which runs on RP-1 and has a hypergolic upper stage, the Atlas V N22, which has
two solid rocket boosters, and RP-1 fueled main center core and a hydrogen powered upper stage and then the Falcon 9 which runs on RP-1. Then let's compare the Delta IV Heavy, which runs entirely on hydrogen, the Space Shuttle, which ran on hydrogen and two massive solid rocket boosters, the SLS or the Space Launch System that is basically a
scaled up space shuttle without the orbiter, and runs on to even bigger
solid rocket boosters and a massive hydrogen tank
and hydrogen upper stage. And lastly, we'll look at Starship and the super heavy booster, which both run entirely on methane. Now you may have noticed a few
things about these choices. First off, I chose these rockets
because they're all rockets that have flown or will fly humans well, except for the Delta IV Heavy, but you'll see why I
wanted to include that one in just a second. But also you'll notice
this selection of rockets covers pretty much all fuel choices. But I should note here, my numbers are pretty accurate. But even direct observation
recordings of rocket exhaust gets confusing because of how
the exhaust actually ends up interacting with the ambient air. There's a lot of little things
like how carbon monoxide will almost immediately
become carbon dioxide, or how the heat of the exhaust turns atmospheric nitrogen
into nitrous oxide. Now because of all these variables, I've simplified their
output by lumping together carbon monoxide and carbon
dioxide into just carbon dioxide, which is quite normal. All other carbon sources
are lumped into soot, and we've just ignored
the slight oxygen output that some engines can produce. Now in general, we combine several sources and our own calculations to actually get a pretty darn accurate
total of each vehicle. I guess we're probably
within about five or 10%. And it seems like our numbers
tend to line up pretty well with some of the other
numbers which for this purpose is good enough for comparison, and at least relative purposes, when comparing all these rockets together. But do put a little small mental ish behind all these numbers, just in case. The hypergolic Titan
II produced mostly CO2, then some water vapor, nitrous oxide, soot and sulfur. The Soyuz FG and Atlas V N22
again produces mostly CO2, some water vapor, soot and nitrous oxides. But because the Atlas V uses
those solid rocket boosters, we see a big jump in chlorine and alumina. The Falcon 9 produces just about double what the Soyuz produces
and that makes sense since it burns about twice as much fuel. It should be noted that the
Falcon 9 and the Soyuz use RP-1 in the open cycle for its engines. This means there's a gas
generator that is very fuel rich. So you'll see much darker smoke coming out of the side of the engine since it has a lot less
complete combustion in the gas generator
compared to the main engine. It's likely the majority of
the exhaust you actually see in the Falcon 9 exhaust trail
is from its gas generators. Although all rocket engines
do actually run fuel rich in the main combustion chamber, for the right balance of heat
management and performance. So there's likely going to
be unburned fuel expelled regardless of the cycle type, but just much more when
it's an open cycle engine. Now if you're sitting
there confused right now and have no idea what I'm talking about, and you need a good rundown
on the gas generator and the different types of engine cycles, be sure to watch my Raptor video because I break down
all the different cycles and make them I think
really easy to comprehend. Okay, now back to our chart. The Delta IV Heavy is really cool because it produces zero
CO2 and just shoots out over 600 tons of water
vapor but as mentioned, it of course will produce
some nitrous oxides in the lower atmosphere and
a small amount of carbon from its ablative nozzles, which causes its exhaust to glow orange instead of the clear
blueish exhaust that we see from the space shuttle's main engines. The space shuttle and it's
bigger wingless brother, the SLS mainly produce CO2, a lot of water vapor, a little soot, nitrous oxide and a whole
lot of chlorine and alumina because of those massive
solid rocket boosters. Lastly Starship will
produce by far the most CO2 and water vapor purely
because of its massive size, and of course, it's gonna
produce some nitrogen oxides. It should be noted quick that
these numbers actually differ from what SpaceX published last year for their Starship
environmental impact assessment. But they were likely worst case scenarios and for a potentially much larger rocket, and our calculations are
based on the nine meter wide 2019 Starship design. But of course, just
looking at their output doesn't really tell the
whole story, does it? What about their payload capacity? This is a number that's going to vary drastically between vehicles. So for this, let's just look at their tons to low Earth orbit capability. So for the Titan II we get 3.5 tons. The Soyuz FG was seven. The Atlas V at 13. The Falcon 9 at 15.5 while being reused like it pretty much always does now. But it should be noted
its expendable payload is a bit more at 22.8. The Delta IV Heavy at 29 tons. The space shuttle at 28 tons. The SLS quoted here is the
Block 1 with 95 tons to LEO. And lastly, Starship will
currently be the king of this group at 100 tons. And now that we have all
these numbers up on screen, here's where the fun begins. We can really do some fun
ratios here to truly see how much work each rocket performs compared to their emissions. So let's start off with their CO2 to low Earth orbit payload ratio. So that means the lower the number here, that's the less CO2 they're producing to actually be able to
really perform work. The Titan II was 10 tons
of CO2 per ton of payload to low Earth orbit. The Soyuz at 35, the Atlas V at 20, the Falcon 9 at 27 when
reused or 19 when expendable, the Delta IV Heavy at zero, the space shuttle at 16, SLS at six and Starship at 27. Next up let's see their water vapor to low Earth orbit payload ratio. So again, the lower the number here, the less water vapor they're
putting in the atmosphere to do the same amount of work. The Titan II produced four tons of H2O per ton of payload to LEO, the Soyuz FG and the Atlas
V N22 are at nine tons, the Falcon 9 is 10 tons when reused or seven when expendable, the Delta IV Heavy produces 22 tons, the space shuttle 35 tons, the SLS will produce 14
tons and Starship, 22 tons. Now lastly, let's compare their
ozone depleting compounds. Again, this was nitrogen oxides, alumina and chlorine to
their payload capability. So again, the lower the number here, the less ozone it's going to
deplete to put stuff in space. All the rockets without
solid rocket boosters produce nearly zero tons per ton to orbit, while the Atlas V N22 produces four tons, the space shuttle, 21.7
and the SLS at 7.7. Now you might notice that the
SLS here performs much better than the space shuttle
in terms of emissions to payload capacity, because the SLS has a much
greater payload capacity than the space shuttle. Now, this is mostly because
the space shuttle had to lug that massive orbiter into orbit, which wasn't actually considered part of its payload capacity. And we're also only comparing
the Block 1 version of SLS, which only has a small, much
less capable upper stage. So things are actually pretty
interesting here, aren't they? Rockets don't really seem
like a very eco friendly way to transport stuff, do they? There's an awful lot of
things coming out of the back per kilogram for every rocket really, but a purely hydrogen powered rocket. But there's a lot of notes here. Here we go. We're going to tangent town. Of course, putting something into orbit requires an unbelievable amount of energy. So as we go forward, keep that in mind. We're not talking about
long haul trucking here. We're talking about
accelerating huge payloads 10 times faster than a bullet. Now, you also may have noticed
me quoting what happens when you expend a Falcon
9 instead of reusing it. And you might be tempted
to think, oh, wow, it emits quite a bit
more per ton of payload when you try and reuse it. Well, this is a topic
we're not really going to talk about too much here because it's a huge, huge rabbit hole. But the manufacturing of
a rocket is much worse for the environment
than the launch itself. But this is where I didn't
want to get too much into the weeds here because
manufacturing of aluminum and steel is a whole different topic and is in no way exclusive to rockets. If we wanted to debate the
impact manufacturing has on our planet, that's a
whole different subject that I don't think we really
need to get to in this video. We're just focusing on the
actual flight of the rocket and what comes out of that flamey end. That being said, in the
case of the Falcon 9, you're much better off reusing a rocket so you can amortize that
pollution and carbon output of the manufacturing process
over several flights, and not just a single flight. I said I wouldn't get into a rabbit hole and here I am, in like the
biggest rabbit hole ever, because we need actually
need to figure out how much the fleet of
recovery vessels emit too, before we really knew the
total lifespan emissions of an expendable rocket
versus a reusable one. But one fun little note
here is that rockets could potentially be a solution
to manufacturing pollution and CO2 emissions. In fact, Jeff Bezos, the founder
of Amazon and Blue Origin, paints a very interesting
picture of what he thinks the future should look like. In May 2019. during a
speech about Blue Origins' proposed Blue Moon lunar
lander, Bezos shared his vision of using rockets to actually
move energy production and heavy industry off Earth, which would then keep earth
as more of a sanctuary in the future. Now, I think this is actually
a really cool concept and it has almost nothing
to do with this video. Sorry. I keep doing this. But you should definitely
watch that speech because it has some
really compelling ideas. But here's another cool note. A rocket running on hydrogen or methane can actually become mostly carbon neutral if the production of the fuels is powered by renewable energy. Unfortunately, most hydrogen
is produced from fossil fuels by steam reforming natural gas, methane or coal gasification. When hydrogen is produced in this manner, it's not a very
sustainable source of fuel. But hydrogen can be
manufactured using electrolysis to extract it from water, although it's relatively inefficient. And you can actually create methane by just pulling carbon
dioxide from the air and adding it to hydrogen
using the sabatier process. This means you can actually
extract the CO2 from the air that's emitted from the rocket
or I guess anything really, and turn it right back into rocket fuel for your next flight. Now, I know this sounds a
bit obtuse, like come on. That can't be right. I mean, isn't it going to take
a lot of energy to do that and that'll just create more emissions? Again, not if you run your fuel production off of renewable energy. This is something that
SpaceX will likely roll out as a cost effective way to not
only fuel up their Starship but it's also good practice
for a vital refuelling process necessary to get home from Mars. That's right. In order to get back from Mars, SpaceX will need to have
this exact process down. So it'll probably make
an awful lot of sense for them to utilize the sabatier process basically right away so they can become experts at it by the time humans will rely
on it to actually get home. But it should be noted. If you're relying on solar
to refuel a Starship on Mars, it will require a lot of solar panels. And boy do I mean a lot. Mars' society founder and full blown Martian
exploration evangelist, Robert Zubrin told Elon
Musk he's concerned about how much solar it
actually take to refuel a single Starship, claiming
it needs to be a solar field the size of six to 10 football fields. To that, Elon said, "So be it." (upbeat music) Now before we try and compare rockets to really anything else like jet liners, we should probably talk
about how rocket emissions have different effects
at different altitudes. Now, because rockets burn their
propellant in all the layers of the atmosphere, including the upper atmosphere
known as the stratosphere, and well even beyond that, their effects can last a lot longer, since they don't actually
end up getting cycled as quickly as down at sea level. And seeing as CO2, soot and water vapor are greenhouse gases, the longer they're in the
air the more time they have to warm up our planet due to a process known as radiative forcing. Water vapor in the lower atmosphere cycles really quickly into clouds and rain and nature pretty much
automatically regulates it. No problem. Although CO2 won't cycle as quickly or as easily as water vapor, it can eventually cycle
out in the troposphere by becoming delicious tree food. But when you put any of
these things really high up in the atmosphere, they tend
to stick around a lot longer. Water vapor is actually
a much more powerful greenhouse gas than CO2. You can kind of think of CO2 as thermostat and water vapor as the heater kind of. But regardless, CO2
emissions in the stratosphere from rockets isn't really that
different than CO2 emissions in the troposphere or lower atmosphere. But carbon, soot and alumina is what we should really be
most concerned about putting in the stratosphere instead
of water vapor or CO2. So rockets that have say SRBs or a RP-1 will produce a fair amount
of soot and or aluminum. And one study actually
showed that they can generate about 30 times more atmospheric heating or radiative forcing
than a hydrolox rocket. And it's actually a
little more confusing here because when it comes to
emissions in the stratosphere versus, say the troposphere, there's actually certain spots
where there's huge impacts. Researchers found that when
jet liners flying conditions that will make those condensation trails, which is the right mix of altitude, humidity and temperature, those frozen ice cloud
like streaks in the sky, that will actually end up trapping a surprising amount of
heat in our atmosphere. One study published in February 2020 by a group of researchers
from Imperial College London found minor changes in jetliners altitude can have drastic changes
on their emissions effects. But researchers all tend to
agree that they really need to study this more to really
accurately calculate and model the impact that stratosphere
commissions have because honestly, it's all very confused. (bright upbeat music) So this is all starting
to get pretty interesting. I think it's time we actually
compare rockets to airliners, and really get a sense
for how bad rockets are, especially when they're used
for transporting people. And I know we've thrown
around a lot of numbers already, a lot. And there really hasn't
been that much context for these numbers. But, I just really wanted
to get it all out there so you know exactly what
gets put into the air when a rocket launches. So let's do a little comparison
of six different vehicles, six very different vehicles. We're going to compare the three vehicles that can currently ferry astronauts to the International Space Station, which is the Falcon 9, the Atlas V N22 and the Soyuz. Then we'll add Starship as well, along with two really common airliners, the Boeing 747-8 and the Boeing 737-800. The reason I chose these
vehicles is because again, they all carry passengers and even more fun, the Falcon 9, Soyuz and the booster of the
Atlas V and the two jets actually run on virtually
the exact same fuel. The Jets run on Jet-A jet fuel, which again is just a
highly refined kerosene while the Rockets run on RP-1 which is an even higher refined kerosene. The reason I put Starship in this mix is mostly because A, it's freaking huge. And for now it represents
a rocket with by far the worst case scenario
for total emissions and B, SpaceX actually wants to use it as a point to point
transportation on Earth. So we'll actually quote the Starship in two configurations:
Starship and super heavy for the orbital spaceflight missions and also just Starship
for those earth to Earth rapid transportation that
might actually directly compete with the airline industry someday. One more note here. We first calculated the worst
case scenario for an airliner, as if they flew full of all of their fuel and had depleted all of their
fuel each and every flight. But it'd be a really bad flight
if your jet ran out of fuel. And airliners only fill a little more than what's actually
necessary for their route. So that being said, we took
their maximum potential output as if their tanks were filled to the brim and then we divided that in half, since that's a much better representation of the overall average amount of fuel used by these jet liners on say, medium or long haul route. Which I should mention really, if we're comparing it to say Starship, we really should only be
comparing the long haul routes. But I figured this was a
pretty decent estimate. And because we can
pretty fairly compare CO2 between rockets and jet liners, let's just focus on the CO2
outputs of all these vehicles. But we wanna keep in mind that the rockets that emit carbon or alumina
to the stratosphere, like the Falcon 9, the
Atlas V and the Soyuz, that's definitely not a good thing. So just like we showed before: the Falcon 9 releases 425
tons of CO2 per flight, the Atlas V, 259 tons, the Soyuz, 243 tons and Starship releases 2683
tons for the full stack, and the Starship alone
only releases 716 tons. Now compare that to a
747 at 302 tons of CO2 and 60 tons for the 737. But now remember, these
numbers have the jets only using half of their fuel per flight. So these numbers could
vary a lot to actually, some of the time, it'll probably
be a lot lower than that. But I figured this was
still a decent estimate of the average CO2 emissions
of each different route. And also, that can vary too, depending on how many
people are in each flight. But yeah, that's not
exclusive to airlines either. So now how about passengers? The Falcon 9 can carry
up to four passengers and a crew dragon capsule, the starliner on top of an Atlas V can
carry four passengers as well. The Soyuz and Soyuz Capsule
can carry three passengers. Starship can carry up to 100
passengers to low Earth orbit. And then after they refuel
it, it could actually take those same 100 people off to the moon, or on really long trips off to Mars. For Starship point to point,
we don't have an exact number. But considering there is
almost 1000 cubic metres of pressurized payload capacity, let's just say 400 passengers could pretty easily be comfortable
for a 45-minute flight. Now compare that to a 747 which can hold up to 416 passengers and only
756 cubic meters of volume. You'll realize 400 in a
Starship for short duration was being quite conservative. And lastly, the 737 can
carry up to 180 passengers. So now how about their CO2 per passenger? Well, here's where some of these rockets really aren't an ideal
form of transportation. With the Falcon 9 at 106.25
tons of CO2 per passenger, the Atlas V at 64.75 per passenger and the Soyuz at 81 tons of
CO2 per passenger per flight. But don't forget low Earth orbit and Dallas are very
different destinations. Now compare that to 26.83
tons of an orbital Starship with 100 people on board and you realize that we can actually make some
pretty drastic improvements to those per passenger numbers. And then just look at Starship
doing sub orbital trips with 400 people, it would come down to only 1.79 tons per passenger. That's actually not that bad. I compare that to a 747
at 0.73 tons per passenger and the 737 is king here at
only 0.33 tons per passenger. So Starship actually gets
pretty close to a 747 at least as far as per
passenger CO2 emissions go. On certain longer haul routes
with certain passenger loads, it might be very comparable. Sure, in general, it could be over twice as bad
on certain routes and things. But at least it's not two
orders of magnitude worse, like some of the other rockets. But don't forget now with carbon capture, we could actually almost null out an entire
Starship flight entirely. And that's something you
just can't do with RP-1 or Jet-A jet fuel, although synthetic jet
fuels are being worked on. But with continued improvements, could we ever get rockets to
be as efficient as jet liners? Now you might be tempted to
think that because rockets only burn fuel for a few minutes, and then they coast in the
frictionless vacuum of space could actually be a really
efficient form of transportation. Well, the problem lies in two main issues. One, a rocket has to counteract
gravity in order to fly. So just to get off the ground, it has to create at least
its own way in thrust before even being begins to move. This is called gravity drag. So imagine if a rocket has a
thrust to weight ratio of 1.2. The relative acceleration is only 0.2 g's because gravity is pulling
it back down with one g. If you gave that same rocket
a thrust to weight ratio of 2.0, you'd essentially
accomplish five times the amount of work because the relative
acceleration is a full g on top of the one g
pulling against the rocket. This is something that planes don't really need to contend with. Their aerodynamic lift is what counters and overcomes gravity. Although this lift can
actually induce drag, the engines themselves
don't really need to waste any of their energy directly
counteracting gravity so planes can fly with a thrust
to weight ratio below one. Although some fighter jets can and do have thrust to weight ratio as beyond one. And that rules. The other issue between rocket engines and jet engines is engine efficiency. Chemical rocket engines, although some are
getting pretty efficient, can't really get much
above about 450 seconds of specific impulse in a vacuum which is their measure of
how much work you can do with X amount of fuel. This is where jet engines
have a huge advantage as their specific impulse is
usually measured in thousands. And they kind of get to cheat by using oxygen from the atmosphere, and also using the air as reaction mass. So a jet engine can just
simply do much, much more work with the same amount of fuel. So despite a jet engine needing
to run for hours and hours to really be able to
cover the same distance that a rocket can do in just seven minutes of burning a rocket engine, a jet engine actually sits
on much, much less fuel during the entire phase, because of its wings providing lift and the jet engines being
so stinking efficient. Whereas the rocket will need
to consume much more fuel in a very short period of time to do the same amount of work. I mean, just look at a rocket and a plane. A rocket is basically all
fuel and a little payload and a plane is basically
the exact opposite. That pretty much tells the
whole story right there, which is definitely why the Skylon hybrid rocket plane concept
would be pretty appealing. It's mixing the best of both worlds. While in the atmosphere, its
SABRE engine uses the oxygen from the air to perform an
efficient air breathing cycle. It uses wings wallets
in the atmosphere too. Once the atmosphere gets
too thin for its engine in that cycle to work or the wings, the engine switch over
to a closed loop system where it performs more like
a traditional rocket engine. This would be a really cool concept that could potentially help bridge the gap between rockets and jet liners. I certainly need do an
updated version of my video about Single Stage to Orbit vehicles and debate whether or not
we'll really ever see them fly. So standby as I think
that's definitely a video I need to redo. (bright upbeat music) So I think it's time we actually look at just how many launches
there are per year and compare them to the
number of flights per year in the commercial airline industry. In 2018, there were 114
orbital launch attempts, which was actually the
most orbital launches in almost 30 years. The majority of launches
came from China that year, with the United States close
behind and SpaceX alone, making up the vast majority
of the US launches. Now in that same year, there were 37, 800,000 commercial
departures of aircraft. So that's 331,579 times more flights than there were rocket launches. CO2 emissions from all
commercial aviation in 2018 totalled 918 million tons of CO2. Now compare that to the 22,780 tons from the aerospace
industry in that same year, and you realize that we
need to fly 40,300 times more rockets per year to
equal the output of airliners. That's 4,594,200 rocket launches a year or 12,586 launches per day. And that's assuming the same ratio of dirty solid rocket boosters, hypergolic or kerolox
rockets that we had in 2018 rather than this new trend we're seeing towards cleaner methalox
or hydrolox alternatives. Although in 2018, with China launching the
most using lots of solids and hypergolic rockets and
increasing their launch rates drastically still, it might be
a bit before cleaner rockets actually outweigh the dirtier ones. Okay, so now we know what it'd
be like to continue launching fairly small rockets, like those from 2018 with
their modest CO2 outputs. Now, how many Starship launches per day would there need to be
two equal airliners? The answer 937 full stack
Starships/super heavy launches, or 3,512 Starship only point
to point launches per day. But hold on, let's pause and remember that we still actually
need to study the effects that water vapor and CO2
have in our stratosphere more in order to actually
understand them better. But even if we find out they're
a whole order of magnitude worse than we previously thought, we'd still be launching an awful
lot of mega rockets per day before it even begins to
compare to the airline industry. Now, believe it or not, the nitrogen oxides that
are formed during reentry can actually have a pretty bad effect on stratospheric ozone. In fact, coming back in for reentry can actually be just as bad
for ozone as the actual ascent. So if a vehicle like Starship were to be flying 5000 times a year, it produced as much damage to the ozone as all meteorites during
that same timeframe. So if we did start to see Starship flying as often as an airliner,
ozone depletion due to reentry and nitrogen oxide emissions on ascent would certainly become
a really big concern that airliners don't really
need to contend with. (bright upbeat music) And now I think it's time we
put airliners into perspective, since we've been using
them as the benchmark for CO2 emissions. CO2 emissions from the airline industry were only 2.4% of global CO2 emissions. So that means in 2018, the
global CO2 output of rockets was only 0.0000059% of all CO2 emissions. In other words, there's
a lot bigger fish to fry. Worrying about the current
CO2 output of rockets compared to the rest of
the world's contributions would be like worrying about
focusing on a single leaf in a forest fire. There's much worse offenders that we should actually be focusing on. Maybe here's something we should actually be focusing on before
we worry about rockets. 2-stroke internal combustion engines. Those small cheap engines
that power leaf blowers, chainsaws, lawn mowers and some jet skis. They only burn about 70% of the gas that you put into them cleanly. The rest actually becomes
pollutants like carbon monoxide, nitrous oxide and hydrocarbons. Tests found that an eco
2-stroke leaf blower is actually a horrible polluter. Generating 23 times the carbon monoxide and nearly 300 times more
non methane hydrocarbons or NMHCs than a Ford F-150 SVT Raptor. So to put that into perspective, the hydrocarbon emissions from
about a half hour yard work with a 2-stroke leaf blower are about the same as
driving 2000 kilometers from Florida to Portland, Maine in a 2011 Ford F-150 SVT Raptor. And as far as the
transportation industry goes, regular old cars and light
duty vehicles on the road make up over 50% of the
transportation industry's global CO2 emissions. So let's just pretend that Starship does actually end up
launching and producing as much as the entire airline
industry currently does. And it doesn't reduce
demand on the airlines, all we got to do is just
reduce total car missions by only 15% globally. Now forget semis, buses,
trains, planes, shipping, don't touch any of those. Just passenger cars. It would actually offset
the entire Starship Point to Point fleet launching
over 3500 times a day. And I'm gonna go ahead
and personally guess that by the time Starship point to point is actually flying consistently
in a decade or two, cars will have made a much
bigger improvement by the in their total emissions. And if Elon Musk actually gets his way, the world will be transitioning
to more sustainable cars sooner rather than later. And we're still not even close to talking about the biggest polluters. Again, if we're worried about
pollution or CO2 emissions, there's a lot bigger fish to fry. I mean, rockets don't even
begin to shift the scales or make a blip on the
radar of global emissions. (bright upbeat music) So rockets are just a tiny little drop in the grand scheme bucket
of emissions currently. But that doesn't mean we should just give them a pass, right? I mean, shouldn't every industry
be working on improvements? So what steps can the
aerospace industry do to actually make tangible improvements? As far as each rocket goes, the most obvious thing to do is stop using solid rocket boosters. SRBs are very bad for our environment. They emit nasty toxic compounds, and they deplete ozone. Then we should probably
move away from hypergolic and fossil fuel based fuels like RP-1. That would be another good step. Utilizing either methane or hydrogen could be more sustainable either by producing
hydrogen from electrolysis or by continuing that
process and extracting CO2 from the atmosphere and making methane. But if we go a step further, the industry should actually be utilizing closed cycle engines like the
RD-180, the RS-25, the RD-181, the full flow stage
combustion cycle Raptor engine and the BE-4, which will
have more complete combustion and not pollute as much
as an open cycle engine with a gas generator, especially when you're burning RP-1. Close cycle engines also tend to have a higher specific impulse, which means they can actually do more work with the same amount of fuel because it's kind of like
a rocket fuel economy. Improving that is a total Win win. But perhaps the biggest thing by far would be to stop throwing rockets away. Again, as I mentioned briefly, the manufacturing of a
rocket produces a lot of CO2 and pollution itself. We didn't even really
get into the half of it. As a matter of fact, manufacturing of steel is a
huge global producer of CO2, which produces about 8%
of global CO2 emissions. But using steel might be a better choice than actually using carbon
composites or carbon fiber, because you will produce
a huge amount of CO2 in the production of that or in the autoclave when you cure it. Now, again, because the
manufacturing process produces all of these emissions, when a rocket gets thrown
away every single launch, we should be tacking on
those emissions to the launch for the total output of the rocket. If a rocket gets reused over and over, you can spread out those
manufacturing emissions over the lifetime of the rocket, which would greatly
reduce the total emissions from the rocket more than any fuel change or engine choice ever really could. But as far as improving
rockets, we should change fuels, change engines and reuse them. It's honestly really that simple. And of course, these are all trends in the aerospace industry anyway. So really, it's a win win. Or perhaps we should all just
plant a few billion trees. # Team Trees. Sorry, I'm so late on this. But for real now is probably
just as good of a time as any to bring up the rear and
plant a few more trees at teamtrees.org. Because whether or not, rockets are really that big of a deal for our air. No one can argue that trees
aren't a really good thing. (upbeat music) So to summarize. How bad are rockets for
our air and our climate? Well, compared to other
forms of transportation, each rocket that launches
isn't great per se. I mean, you probably
wouldn't wanna start shipping simple packages via rockets. But then again, the cost
will probably always keep that off the table anyway. But compared to even a small
player in total CO2 emissions like the airline industry, rockets currently don't
even compare at all. We'd need several orders
of magnitude, more launches to even begin to need to
factor in their contributions compared to other industries. So obviously, rockets aren't ideal. But for now, they're all we've got. And it's gonna be a
really, really long time before we need to worry about
the environmental impact that they have on our air, at least compared to quite frankly, just about everything else. And not to mention that
possibility of potentially moving heavy industry off of
our planet using rockets. Perhaps their mild emissions could end up being our
planet's biggest savior. And besides, if it weren't for rockets, we wouldn't have the observation and data collecting
satellites that we can use to actually monitor our planet well, and other worlds to
further shape our knowledge about our place amongst the universe, and our effects on our own little planet. So what do you guys think? Do you think rockets are a terrible thing and we absolutely need to stop
launching them immediately? Do you think there's something
that we kind of just need to pay attention to and tweak and hope that we can make improvements on? Or do you think they're just
really not that big of a deal compared to everything else? Let me know your thoughts
in the comments below. I have some very special
things to give for this video because this was a really hard one. And if it wasn't for people
like Lisa Stojafoski, who helped me actually
research a lot of these topics, or Maryliz Bender and Ryan Chylinski from Cosmic Perspective
for helping me shoot some of those scenes and some of these
beautiful rocket launches, I wouldn't have had such an awesome video. Or especially big thanks to Kennedy Space Centre
Visitor Complex for allowing me to actually go out there and
shoot in the rocket garden. I mean, what a dream come true. How awesome was that? But of course, I still
owe a huge, huge thank you to my Patreon supporters. Guys, this one just about ruined me. And you were so patient in helping me figure out all these strange,
little nuanced details of this topic. And you really gave me
some excellent feedback. So I owe the biggest thank you to you for not only being patient but for also helping
me script and research. If this is something you wanna help do if you were sitting here wishing that you could contribute or maybe add your opinion on
the script before it comes out, consider becoming a Patreon member. Well, you'll gain access
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earth for everyday people. (bright upbeat music)
Tim, your content is fantastic. Thanks for all the time you put into these!
environmental impact is close to 0, its comparatively an extremely small industry, it will not even compare to air flight or automobile transportaiton in terms of pollution for the next couple of hundreds years at least
Hey Tim! As an engineer in the industry I gotta say I absolutely love your work. Thank you for all you do.
I am so annoyed when rockets are compared to airliners no matter what ppl compare.
Reusability? It can be done with aircraft so it HAS to make sense when it comes to rockets.
Price? Rockets should cost 5€ per pound.
Launch rate? We just land the rocket fill it up and 5 mins later we start again.
I think people should really remember 2 things.
1st Rockets operate at their maximum designed performance they have very little margin of error an engine underperforming by 5% well your mission is over.
2nd Rockets are cool and interesting BUT the rocket is actually not the most important part of the misson, the payload is it's more valuable and the rocket is just the mule to get it into a specific orbit/trajectory.
Sorry for bad english and great video, I didn't want to rant but comparing rockets to aircraft feels so wrong on many levels to me.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
[Thread #345 for this sub, first seen 21st Mar 2020, 06:44] [FAQ] [Full list] [Contact] [Source code]
I really appreciate these sort of videos. Even if we were to find that they had a highly negative impact, the priority would simply move to finding ways to mitigate that. We probably need to become interplanetary to ensure our species' survival, just as much as we need to find ways to maintain quality of life without also destroying the biosphere.