Is The Expanse Scientifically Accurate? - Asteroids

In season 5 of the Expanse tragedy strikes the Earth in the form of an asteroid. How accurate does the expanse get asteroid strikes, and is there anything we can learn from this grim but hopeful future?
#season5 #expanse # asteroid

[@delvinciposterkid]

9:30 The dolphins left hours ago... ...and they left a thank you note.

[@mkocel]

lol i get that reference.

[@jeanbonnefoy1377]

Too bad it's at 9:30 and not at 9:42 (don't thank me for the fish)

[@DavidOfWhitehills]

The lawyers were close behind the dolphins...

[@DavidOfWhitehills]

... and they left an invoice.

[@nox9856]

Did they thank us for all the fish we gave them?

[@rozzgrey801]

We see one asteroid break up as it nears the sun, so I think Marco sent the stealth asteroids on a trajectory around the sun so they would approach from it's direction, making them even harder to spot. We often discover near-Earth asteroids after they've passed close to us as they were approaching from the direction of the sun. I love the Expanse and asteroids!

[@RyanRidden]

Great point to highlight! Even with future super telescopes, I bet it would still be really hard to spot asteroids near the Sun.

[@quiett6191]

thats an old fighter pilot trick, from as far back as WW1. When the sun is behind you, the target is blinded when looking in your direction, giving you a chance to get close.

[@cmdrTremyss]

@@quiett6191 The technique was used long before that. Persians used to shoot thousands of arrows at once in a trajectory, where their flight path blocked the view of the Sun. Making them very hard to detect by spartan technology of that era.

[@tedarcher9120]

He was probably launching asteroids for months on different trajectories so that they would arrive approximately at the same timep

[@tedarcher9120]

@@cmdrTremyss LoL

[@UncleSlimJimmy]

Well I was able to successfully combust after hearing "The Expanse is a terrible show" because I my friend, am a fanboy lol.

[@RyanRidden]

There is no better show to be a fanboy of!

[@UncleSlimJimmy]

@@RyanRidden Oh for sure! And also just 'cause I didn't mention this in my comment, your video is very high quality and well edited. Keep up the great work!

[@darkstorminc]

@@RyanRidden but but but... Buck Rogers! Stargate! Firefly! Lexx!!

[@RyanRidden]

@@darkstorminc I'm a massive Firefly fan, the Reavers were such an interesting concept!

[@darkstorminc]

@@RyanRidden it was a shame the show didn't last. At least there was a movie to tie up loose ends. Oh, and do you happen to watch any of the videos by Isaac Arthur?

[@rot_studios]

Another nice detail is that the beach-guy's skin is burning from the intense heatwave coming from the impact.

[@junglemoose2164]

"Everyone has a plan until an asteroid hits their planet." - Mike Tyson probably.

[@pablom-f8762]

"Until they get rocked?" (elbow to the ribs)...

[@Yesquire0]

It is specifically mentioned in the show by Ashford that Marco selected solid iron asteroids for his attack. One problem in trying to assess the impact damage is there really were no scenes where some familiar object was shown alongside one of the asteroids to allow us to estimate its size. We maybe saw a ship near one, but didn't know the size of the ship. It's pretty clear that they weren't gigantic, but my best guesstimate would be anywhere from 250 yards in average diameter to maybe 1000 yards. The books depict the immediate damage from the attack as having been far more extensive and severe than what we've been shown so far on the TV series, primarily, IIRC, the fires caused by molten ejecta from the impact craters. I've been trying to figure out exactly how it happened that so many of the attack asteroids missed Terra entirely. We can launch probes that travel for years and arrive exactly where intended. Maybe Marco and his scientists never had a precise measure of the mass of these irregularly shaped objects, or, possibly, they lacked any attitude jets to make in course adjustments for any inaccuracies in the initial calculations. Or maybe the vector of the ships that launched them on their journey to a desired collision point were off a teeny-tiny fraction. Overall, the smaller scale of the immediate damages caused by Marco's attack may have been dictated by cgi budget considerations. Less damage meant the show could just film at a lot of normal, undamaged locales. Did any of you find it upsetting that the Philadelphia impact levelled the portion of the concrete and steel supermax prison that had stood above ground, but did no discernible damage to the surrounding forests?

[@angelaguidolin4822]

I saw many flatten trees.

[@Yesquire0]

It's not a huge point, and not worth debating at length. The show has just been so incredibly logically consistent for 4.5 seasons that a breach in logic stands out like a large zit on the tip of a supermodel's nose. I'd agree that the land beside the prison was depicted as devastated, but the show also told us that, IIRC, the supermax prison extended seven stories above ground, and was built with concrete and steel. Yet we see Amos and Melissa hiking through undisturbed pine forests within one day's walk from the prison. That area should have looked like the forests that took the brunt of the Mt. St. Helens eruption the day after the explosion. Maybe they should have inserted a scene where Amos and Melissa were discovered by a helicopter looking for survivors and evacuated by air to a location outside the devastated zone. Maybe they filmed one , then cut it from the final edit.

[@RyanRidden]

Great points! Like you say, boosting irregular asteroids into intersection orbits would be a challenge for anyone. It's made even harder when you consider that outgassing from the Sun heating up the asteroid would change the orbit along the way. As well as flattened tree you might also expect to have some pretty sever forest fires break out. Finding and filming in a burnt snowy forest would probably be too hard logistically, so I've got no problem with it.

[@macmcleod1188]

In the book's the Earth Fleet is pinned down for quite a while at Earth against further asteroids coming in. I get the impression in the show that there are additional asteroids on the way. I also saw a flat in forest and presume that the forest that we see later in the show are quite far away from the impact site. And the show The Asteroids appeared to be fairly small. I believe in one seeing you can distinguish human beings covering them the stealth material. My impression was they were under 100 m in size.

[@DerpyAngel09]

I'm no astrophysicist, but your 250yrd guesstimate even seems too big considering the ATLAS telescope system classed impactors in the 100m+ size range to be of the "country killer" variety and how the UNN was still very much active after multiple attacks. However, in feet it seems more reasonable considering the damage we see in the show, at least up to about ~250ft much beyond that and you're already in the country killer weight class.

[@MartinCHorowitz]

The Fish were Mackerel so we could have a holy Mackerel Moment......

[@RyanRidden]

Brilliant!

[@andykoegelenberg6376]

No No the were Red Herrings.

[@RyanRidden]

Something fishy happens thats for sure!

[@MartinCHorowitz]

@@andykoegelenberg6376 I get your Joke, but if you Freeze frame the fish viewer display you will see it ID's the Fish as Atlantic Mackerel .

[@rabid_si]

They were just following the dolphins. So long... and thanks...

[@caffiend81]

30,000 KPH is much closer to what I'd expect in MPH. I wonder if they read something somewhere then missed, or forgot to convert, the units? If I did my math right 30,000 MPH is a little over 13.4 km/s which is on the low end of possible impact velocities.

[@Blackpearlmatt]

I remember reading somewhere that during calculations they used imperial, this is mainly seen when they deal with distances and how quickly they seem to get places

[@guicho271828]

I would die if I time-travel to Expanse universe and realize that imperial is still a thing

[@mostlymessingabout]

@@guicho271828 imperial should die now. It's already caused many accidents and deaths due to cross conversions

[@jakethet3206]

Or MAYBE, and I’m just spitballing here... Avasarala and the Admiral know that if it’s happening, it’s man-made, so perhaps the speeds aren’t supposed to be representation natural speeds. Because, you know, THEY’RE NOT.

[@Blackpearlmatt]

@@jakethet3206 if those speeds were made up then the physicist would be damn confused because certain things cause certain reactions. You could fake them but there would be little to no reason to do so when you are actively trying to get help on what the hell is going on out there

[@dapeach06]

I think the fish jumping was just a coincidence, the show wasn't trying to connect the fish jumping to the asteroid impacts, it just conveniently placed that man in a place where he could be the first casualty

[@RyanRidden]

It certainly makes for a great way to build suspense!

[@MikeAben]

Funny, I took the fish jumping to be them reacting to the shock wave. Does sound not travel faster in the water? Then again, I believe it's even faster through the ground.

[@dapeach06]

@@MikeAben the asteroid was moving so fast that it passed through the entire atmosphere in less than a second. There's no shockwave to feel when the rock is still in vacuum

[@MikeAben]

@@dapeach06 I'm thinking the shock wave from the impact. I could easily be remembering the scene wrong but if the fish were jumping before the fireball was seen, then I'll just shut up now. Edited to add: Yup, just watched the scene. I remembered it wrong.

[@Justanotherconsumer]

Unlikely that he was the first casualty, he just had a great seat for the show. Maybe a little too close, though.

[@Dash101]

There is no forgivable excuse for having a Prime Video subscription without having watched this jewel to TV

[@juanc5149]

The fish fly to space in case of asteroid impacts. Everyone knows this.

[@mytester6208]

The fishes are part of the earth defense system sensory, so it is incorrect they are running, they are actually warning people with this behaviour...

[@michajastrzebski4383]

Well I beg your pardon good sir. Aquatic mammals are not fish! :D

[@mkocel]

Ur thinking of the dolphins

[@dapeach06]

One thing that they don't seem to be playing up that much in the show is that in the books they accelerated the rocks for quite a while before letting them go and head toward Earth, so they were almost certainly going much much faster than 17 km per second, so all of the estimates by those people on the show are extremely low

[@RyanRidden]

I really need to read the books, it sounds like they go into a lot more detail! Since kinetic energy depends on velocity squared, underestimating the velocity can really lead to a massive underestimate in impact energy. So not something you want to get wrong!

[@iliketrains0pwned]

I think that might have actually helped the story out in a way. Not a lot of people in the UN really knew there were rocks on the way, and anyone that suspected it probably had very little data to work with; Chrissie included. It might have unintentionally made the rocks even more devastating than expected. And in the chaos and confusion of the aftermath, it's probably gonna be a while before we see the real parameters, damage reports, and death tolls in the show.

[@abbofun9022]

I read it as accelerate to change course and not so much to increase speed.

[@dapeach06]

@@abbofun9022 well first they would have to deorbit the asteroids so they would head sunward towards Earth. But then, in order to create the level of devastation in the books, they would have to be massively accelerated, well beyond 17kms. Or they may not have been natural asteroids in the books at all. Amos speculates that they could have been large blocks of tungsten, super accelerated

[@thomashiggins9320]

@@RyanRidden In the books, the asteroids are a lot more devastating, because they moved so fast. They ramped that down, a bit, for the show. That's a pattern with the TV series. In the books, a million people, mostly Belters, lived on Eros. in the TV series, they dropped that number to 100,000. I'm not sure why they did that. Maybe to make the scale of the tragedies more comprehensible? Of course, they may have just decided to revamp things, a bit, based on a better scientific understanding of things. I do know the notion of spinning up asteroids and putting habitats on the inside of them was kind of a thing in popular science, 10-15 years ago, when they started writing the books. You can't really blame a writer for using the popular science of the day, even if it turns out (as it did) that the idea wouldn't work. (Asteroids don't have the structural integrity to survive being spun up fast enough to produce useful gravity, for people walking around inside them. They would just fly apart. Better to dig wide shafts into them, and then build O'Neill cynlinder habitats inside those. That way, the bulk of the asteroid shields the habitats, and the resources are readily available to the residents.)

[@Sweenus987]

Wait, I just noticed, in the scene where the clouds evaporate, is the dude's skin burning?

[@dragonsword7370]

Did you notice that he was watching the kinetic fireball "plume" or mushroom cloud as it rose, before the shockwave reached out to the fisherman? I Don't want to go out on a limb and state that a meteor impact of that size and speed would create an impact fireball exactly like a nuclear explosion, I will state that it would get hot enough to be half as close...maybe

[@HeadHunterSix]

@@dragonsword7370 Intense heat is exactly how this kinetic energy would be released, and the temperatures would not differ by any significant way. Hot enough to vaporize is sufficient whether it's 2400 C or 5000 or whatever.

[@Steampunk_Ocelot]

Im rewatching for the third time, im at the end of season 2 ATM. I pick up new details every time I watch and while im not a scientist the factual accuracy makes me super happy

[@pxzallen]

Check out the, now very old, scifi novel: The Moon is a Harsh Mistress, by Heinlein. I expect that the writers borrowed a great deal from it to make the Expanse so believable.

[@Kazemahou]

I have read every book Heinlein ever wrote. Big Heinlein fan. Reading the Expanse is, for me, like reading Heinlein fan-fiction. I read the books to one of my spouses, and we have this game. We make a fuss and point out every time the authors make a direct, or partial, recreation of a line from a Heinlein novel or short story. We know these lines like some people can quote Monty Python. We find an average of three to four direct references per chapter. Could be a phrase, could be a word only Heinlein ever used (or invented!), could be an entire sentence. The Expanse is basically a love-letter to Robert A. Heinlein, and that is wonderful!

[@edbouhl3100]

@@Kazemahou Bet you counted ‘waldos’ a few times, eh.

[@suzannerozario3578]

Check out “The Stars My Destination“ by Alfred Bester. I think at least one of the authors of “The Expanse” must be a fan of that book.

[@TabaquiJackal906]

Check out, as well, 'Heavy Time' and 'Hellburner' (omnibus 'Devil to the Belt') by C J Cherryh. Written well before The Expanse, it also tackles 'the belt', belters, Earth, Mars, and all the tensions and political rivalries that happen as humanity expands outward.

[@kirkdarling4120]

@@Kazemahou Totally agree. I squeaked aloud when they did a flip-and-burn (skew flip) and again when they touched helmets to speak without radio. "Have Space-Suit Will Travel," "Starship Troopers," and "The Moon is a Harsh Mistress" all over the place. "Belters," though...that's Larry Niven.

[@stuffedwalrus]

So long, and thanks for all the fish!

[@RyanRidden]

Too bad it had to come to this.

[@rj2552]

Avasarala tried to warn them but they didn't listen

[@tonycrabtree3416]

You win! lol

[@stuffedwalrus]

@@rj2552 There's that part in season one where she is lying on the roof with her grandson talking about shooting stars and dinosaurs. she says "no one can throw rocks that big", forewhadowing or what!?!?!

[@rj2552]

@@stuffedwalrus whoa. Just watched the clip, it's her grandson that says it. Still...yikes.

[@davidknisely3003]

One minor quibble: meteoroids do not burn up mainly due to "friction" but due to heating caused by the intense compression of the air out ahead of the incoming object as it slams into the atmosphere at high speed. The compression induces extreme heating of that atmospheric gas, and that is what does most of the job of burning up smaller meteoroids before they reach the ground.

[@Lucas12v]

When discussing asteroid energy, the guy in the show said "impact velocity." could he have been talking about velocity at ground level after having been slowed by the atmosphere?

[@Alessandro-B]

They would hardly be slowed down that much by our atmosphere. Depending on the angle of descent, an asteroid might take 10 seconds to impact after the first contact with the atmosphere about 150/200 km up. And the atmosphere is really dense only in the last 20 km or so, which it would traverse in less than 2 seconds.

[@Lucas12v]

@@Alessandro-B that makes sense. Odd that a show would downplay something dramatic like a huge velocity number but i doubt that it was intentional.

[@mylesleggette7520]

@@Lucas12v Remember, the guy they're talking to thinks this is some confusingly pointless hypothetical question and he has had literally no time to prepare or think about it. I wouldn't expect precise or accurate numbers in that situation.

[@StargazerFS128]

Your analysis are great, I also am a huge fan of Expanse, thanks for making it even better.

[@writerchick94]

You look and sound (not just your accent but the speed that you talk and your cadence) just like the math and physics KZbinr tibees, it's crazy

[@RyanRidden]

Weird, I never noticed! Tibees makes great videos, so I'm in good company there!

[@UteChewb]

@@RyanRidden , same here, I was thinking that you might be related to her.

[@cameragod1]

I thought asteroids that enter the atmosphere are by definition a meteor? So linguistically speaking its impossible to hit the Earth with an asteroid... meteors on the other hand... :)

[@RyanRidden]

You're certainly right! After getting annoyed at the kind of pointless language barrier with meteor, meteoroid and meteorite, I defaulted to calling them all asteroids!

[@michaeldublg]

Actually, An asteroid are large, very large rocks in space. ... (Meteoroids) are small rocks in space. ... Once a meteor(oid) enters the Earth's atmosphere, it then becomes a (meteor) .... An (asteroid) enters the Earth's atmosphere still a very very large Rock and maintains the title of asteroid.

[@tisFrancesfault]

A note on destroying asteroids is if the debris even in as dust still hits the earth they're still quite the threat; All that kinetic energy will will dissipate in the air via friction heating it to hundreds of degree Celsius. Its okay with small ones as the heat will be circulated high up and dissipate, though the largest would turn the earths atmosphere into an oven till the sea absorbs enough heat and it radiates into space. Sometimes it may be better to let it hit intact.

[@RyanRidden]

Great point! In that case, the ideal way to deal with a big asteroid would be to redirect it through directed outgassing using mirrors or lasers.

[@pschroeter1]

I binge watched all 5 seasons of The Expanse in March. It's going to feel weird to be on a weekly schedule and not be able to watch two or more episodes a night.

[@lrvogt1257]

Yes. The Expanse is a fantastic show. The fish jumping could have been coincidental or they were sensing the unusual disturbance as the meteor hits the atmosphere. Certainly nothing psychic. Not only did the clouds evaporate but the mans face began burn.

[@chrislockwood]

In his remark about the speed being too slow, I think he is comparing Marco's asteroids to objects coming from the outer solar system, not the asteroid belt. If you took a Kuiper belt object with an orbital velocity of about 4.2 km/sec and deflected its orbit to be eccentric without affecting its velocity, so it was headed toward the inner solar system, its maximum speed would be about roughly 38 km/sec at its closest distance from the sun depending on how close it actually gets without hitting it. That's because it's constantly picking up speed as it falls toward the inner solar system. As it crosses Earth's orbit it's not nearly going that fast. Assuming that Marco is getting his asteroids from the asteroid belt (and he doesn't have unlimited power to change their velocity), wouldn't these asteroids be traveling slower than objects coming from the outer solar system since they don't have as much time to pick up speed? Remember, you don't have to accelerate these rocks very much, just enough to change their vector. Gravity and orbital mechanics will do the rest.

[@LukeDavisAuthor]

Expanse meets Hitchikers guide to the galaxy. So long and thanks for all the fish.

[@TheBeardyPenguin]

I've just discovered your channel and I have to say I love it! Really well put together and very clearly spoken. +1 subscriber :)

[@shawncarroll5255]

One brilliant hard science moment was the shattering of the asteroid passing nesr the sun. Considering the black apearance of the stealth tech, and fact that the reflection of electromagnetic radiation is generally highly undersirable for hiding something, the asteroid may have been heating an an unsustainable rate. It may have shattered due to extremely rapid surface heating, with the surface simply expanding so much faster than the rate of heat conduction to the center that it essentially catastrophically failed. Weak areas from previous collisions could provide fault lines for cracks to rapidly propagate once a certain point, leading to a shattering effect. If the iron-nickel has silicate contaminants, you will get differential rates of expansion in the two materials, leading to the same effect. You can combine these with water, ammonia, or other ices turning gaseous as suggested by the video. The velocity he is using for the asteroids is way too low for an attack. If you are deliberately slingshotting asteroids around the sun, there is no reason to not maximize the delta-v of the asteroid. You might only accelerate it to the upper range of natural objects, but you could also argue that going faster may make them harder to detect since they aren't looking for them coming in at that velocity. Since they were going to take credit for the sttack, and there were too many asteroids for this to not be deliberate, after the first two or three there is no reason not to have the last five asteroids coming in all together, with some at the highest practical velocity. How high? In the next 60 days, the JPL site for Near Earth bjectz shows oe object that would have an impact velocity of 34 kps and a size of between .77 and 1.7 km - object231937 (2001 FO32). Since it's e=mv(squared), at four times the assumed velocity from the episode - from 8 to 32 kps gives you four times the velocity, or 16 times the energy,yielding 16-64 megatons. The upper edge of that is Tsar-Bomba sized, the highest yield thermonuclear device ever detonated. At these yields you start to see damage at the level they are showing in the special effects, with some decent sized tsunamis. You will also get a fair degree of fallout. The largest fragment of Schumaker-Levy hit Jupiter with an estimated 6,000 megaton impact, but that was in the kilometers size and I remember around 60 kps. cneos.jpl.nasa.gov/ca/ Gravity assist has been used to change satellite velocities by up to around 30 kps I believe, so this is well within our ability to create even now. It maybe a little more difficult since the asteroid will not be able to use a the Oberth effect, i.e. accelerating at it's closest approach to the Sun. What we really need is the mass of the ship plus asteroid, and the length of burn and thrust produced by the engines being used. That energy can be redirected into another relative velocity at impact. Think of the difference between a car at 40mph rear-ending another car going 30 mph. Now think of the same collision, head-on. Slingshotting around the sun let's you cheat and change the direction of the asteroid for no energy cost too the asteroid. Timing is all important here, so you probably will only have one optimized asteroid collision, with the others having less ideal solutions if you are trying to deliver them together. en.wikipedia.org/wiki/Gravity_assist. Or, Moe simply - asteroid impact very bad...

[@alans3023]

Really enjoyed the explanation (and the one about space walking in hard vacuum) so thank you for adding to my enjoyment of this excellent series.

[@kassistwisted]

Last line slayed me. Thanks, Dr. Ridden! LOL

[@stevenschofield8518]

Yeah I notice that fish thing too....I was like wtf ..... thank you for these videos I’m definitely liking your style.....totally subscribing looking forward to more Expanse videos.... keep me coming Doc ; )

[@ES-1984]

Ryan is there any chance that the fish could sense the metallic asteroid moving through the earth's magnetic field? I enjoyed your video by the way and subscribed for your take on the expanse.

[@RyanRidden]

Great question and thanks for subscribing! Quite a few fish species can detect the Earth's magnetic field so its something worth considering. In general it looks like metallic asteroids don't have a very strong or ordered magnetic field. Any magnetism would likely be the result iron atoms aligning from smaller asteroid impacts over time, just like how you can make an iron bar magnetic by hitting it hard enough. Even if an asteroid doesn't have much of a magnetic field, simply moving a large chunk of iron through a magnetic field will cause some changes, but they would be really small changes. Based on the magnitudes of these fields, I think it would be very unlikely that the magnetic field change would be detectable to fish. Another point to consider is the speed at which the asteroid is moving. At say an average velocity of 17 km/s it would pass through the bulk of our atmosphere (troposphere) in less than a second, so not much time for anything to react at all. As far as scientific inaccuracies go, this is really insignificant. The fish served a fantastic tool to crank up anticipation for the impact! If there are any other points in the Expanse that you would like to see an astrophysicists take on, let me know!

[@ES-1984]

@@RyanRidden thanks for your great answer and if I think of any other points of interest I will let you know.

[@matfax]

Maybe it's just coincidence that he's looking at fish swarms.

[@Zantides]

I almost lost hope for The Expanse for some time, but season 5 have been bloody good.

[@tajsarin1019]

Came across your vids when searching for Expanse content, awesome, huge fan of and studied astrophysics myself for a brief period of time!

[@Jorge01234]

Certain or all types of fish probably sense a disturbance in the Earth's magnetic field kind of like birds do so this could be scientifically accurate.

[@ghislainbugnicourt3709]

Here are my interrogations while watching : - At the end of season 4, Inaros takes 2 asteroids from a group of 5. It felt like they were clumped together, more than they should. Am I right ? What's the usual distance distribution between asteroids ? - In the media reports with shots of impacts seen from satellites, we see a shockwave going very fast. I though it was too fast but I really have no idea of the shockwave speed.

[@billkallas1762]

In the last two weeks scientists were talking about a 50m that passed between us and the Moon.. I did some digging and discovered that a 50m asteroid would mostly break up in the atmosphere but would destroy every frame built house within 10 miles of where it exploded in the atmosphere. It would also destroy reinforced concrete building within shorter distances.

[@JeffTY77450]

Very interesting and informative (and understandable), thank you.

[@walterwillis5351]

Well, cats and dogs have been known to sense an earthquake before the ground starts shaking, so I guess fish could sense disaster.

[@nemo4evr]

Fish like many animals appear to detect the electromagnetic fields of earth, I don't know if an asteroid would disrupt it enough at that great speed for them to react in time as well. The Expanse IMHO is the best sci fiction in the last ten years, the last season has become unfortunately a crying soap opera, I can't for the life of me see the end of it and the start of a new season, hopefully they will then get on with the program, stop the crying and family drama and keep giving us the great space stories we are so starved for. On another note, change the camera lens or sit back more from it, the way it distorts your head makes it look like a talking bobble head ;-) you also got one new sub partner! cheers from Canada

[@aniket33591]

Redirecting such smaller asteroid fragments at random locations in space like the battleships guarding the ring gate is indeed scientifically inaccurate at so many levels.

[@MetallF]

One small detail I noticed, they say that the asteroids are "nickel-iron slag rocks". I figure the "slag" part means the asteroids are artificial and a byproduct of some industrial process, making them virtually a dense iron-nickel chunk ?

[@RyanRidden]

I missed that, definitely an interesting idea!

[@kellerkind6169]

When an asteroid (or any other physical body for that matter) enters earth athomosphere it IS NOT friction that generates the heat, as you said in the video. The heat is being generated by compression of the air in front of object thats entering the athmosphere. Sorry for my wonky english, I'm not a native speaker. I just thought being a physcist you should probably know that.

[@RyanRidden]

The compressed air generates heat because of friction between particles.

[@adamrak7560]

​@@RyanRidden no, there is no friction between gas particles at all, it is not even defined. Friction is defined in a macroscopic sense, but it does not play a role here. (edit: you probably call the molecular "bouncing action" friction so you are right, but that is just really confusing, you should be more pedantic) Compression generates heat because of simple physics: if you compress gas, you push it with a force and the volume becomes smaller. But if displacement times force is energy. You put work into the gas, which means you give it energy. But it is confined, so the the energy heats it up. Microscopically you can imagine gas made up from perfectly elastic balls bouncing around (only noble gases are balls, but close enough). If you push the wall of the container inside, every ball bounces off faster from the wall than if came to the wall. Basically it is like you are hitting back the balls. But the balls are perfectly elastic, so they keep accelerating as you push back the wall. Temperature is kinetic energy = how fast the balls are going, so if you push the walls inside to lower the volume, you are heating the system up. Air friction is _not_ defined in this view at all. If you want to define it you need to average out the velocities of the very fast air molecules, so you get wind. You can understand air friction (drag, viscosity) as changing the average velocity of many air molecules (like wind), giving kinetic energy to the air molecules in an ordered macroscopic way. (This is only possible if your speed is much lower than the speed of the air molecules, so you can ignore the microscopic behavior.)

[@nomdeguerre7265]

What I really love is the fabric thin radiation shielding materials! Sure glad NASA came up with that! :0

[@mmabri]

Enjoy the Expanse, and hearing how scientifically accurate it is makes me like it even more. Have you considered doing a video on how we could actually stop an asteroid impact if one was detected. I know 3 weeks out we'd have no chance, but lets say we detect a country killer sized asteroid coming our way 1 or 2 years out. Could we actually prevent it?

[@scirrhia_kruden]

Is the typical 17km/s on impact with atmosphere or with the ground? If it's with atmosphere, then the 8 km/s number makes sense for impact with the ground, especially considering the scientist is approximating the destructive potential of the impact. There's little destructive impact from just hitting the atmosphere, and only the velocity on final impact matters for how much destruction it would really cause.

[@brownro214]

Ryan, my issue with the way they handled the asteroids is how quickly they were able to adjust the asteroids course and hit the Earth. It doesn't take a huge amount of energy to make a small adjustment in the asteroids course, but a small adjustment means it might take years for the course change to result in intersection with Earth. Making a large change that moves an asteroid from the asteroid belt into Earth's orbit over just a few months would take more energy and over a sustained period of time than they depicted.

[@Marinus_Calamari]

With current technology, yes, but in the future of the Expense, technological advances have made interplanetary travel within the Solar system a more or less trivial endeavor. If you can takes a ship from the Belt to earth in a couple of weeks you can do the same with anything ship-sized you can strap a fusion drive on.

[@CrazyStarClaire]

Safe assumption that they meant 30,000 kilometers per second. That would put the velocity about right.

[@NozomuYume]

I'm not even certain the fish were real. The guy was playing an augmented reality fishing game with virtual fishing gear. The fish might be just as virtual as the fishing gear. Remember, Earth's biosphere is kinda screwed at this point and they're trying to repair it, so fish stocks may not exactly be plentiful.

[@RyanRidden]

Great point!

[@Kazemahou]

I have a Marvel No-Prize answer to explain the 'psychic fish': the asteroid entering the atmosphere locally shocks the air (thus the clouds evaporating) and, I would argue, there would be a sudden, ear-popping pressure change for several kilometers around the projected impact point. Perhaps that change in pressure could be communicated to the liquid environment of the sea, perhaps as an uncomfortable vibration in the water. Additionally, the light from the plasma-shrouded asteroid punching through the atmosphere could have frightened sea life in the same manner that shining a bright search light on the ocean can cause fish to scatter. I even have anecdotal evidence for this latter claim - during a total eclipse I witnessed, one aspect of the experience was especially astonishing to me; the world fell silent. All birdsong stopped. All the barking of dogs ended. The crows, normally cawing loudly at any disturbance fell silent. Every animal became utterly, totally silent for the duration of the totality. Before it, they seemed nervous, scared, and made great noise. Afterwards, they also made great noise, as if reacting to fear. It took them some time to settle down. But... during the totality, the world became silent as a tomb. The animals - all the animals - reacted strongly to the change in light. I think the flickering, dancing glow of an approaching gigantic meteor just might scare the fish for kilometers around - any place that the light would shine. Even if my notion of atmospheric shock being transmitted into the ocean is bollocks, surely a reaction to a sudden change in lighting is reasonable? (Sorry to step on your joke, but I felt compelled to see if I could solve for it at all!)

[@frankscruggs9089]

Did anybody else notice that the beach guy was wearing fish Finder glasses??

[@rogeriopenna9014]

There is something that is quite innacurate scientifically in the Expanse show: the HOLOGRAMS. Just like in other movies and series, Expanse holograms are able to be projected... in clean air, around the characters.

[@moistmike4150]

I read the book series years ago and the stealth asteroid attack still haunts my dreams. At least 2 billions of people killed in the initial blasts and billions more from disease, starvation and human predation afterward. The horror is almost beyond what one can contemplate.

[@fredlandry6170]

I didn’t think about the clouds vaporizing during the asteroid hitting in Africa nice touch.

[@diegomorett142]

Could it be that the velocity is "only" 30,000 KPH because the asteroids were artificially deviated from their normal orbit, thus slowing them down to bring them into a collision course with Earth?

[@christianhagenhoff2004]

No, the asteroids would have to be going at least at the earth's escape velocity, since that is the speed the earth's gravity adds to any asteroid it encounters.

[@RagnarokLoW]

wouldnt an iron-nickel asteroid impact the earth's magnetic field? If so the fish may be able to detect that change?

[@abirbinhabib7669]

the fishes moving away actually makes sense as animals somehow know about impending disaster right before it occurs.

[@MaciejRebisz]

Great analysis! Regarding the fish trying to escape - speed of sound in the air is quite slow, but what if sonic boom from the asteroid entering the atmosphere hits the water first - we can see that asteroid is quite a way out into the ocean, so the water surface is closer to the asteroid than to that poor man. Fish could easily feel that and start panicking a few seconds earlier than we could hear the asteroid.

[@ghislainbugnicourt3709]

In that scene the fish event happens even before the rock reaches the atmosphere. I see no way they could "know". Also I believe the shockwave is faster than sound, that close from impact.

[@francisdavis1271]

As an aerospace engineer I have problems with their point defense and rail gun systems. If you have fusion as a drive (and power source) you have massive amount of power to drive lasers: You don't want to have "ammo" be limited. Railguns may be considerably higher velocity but can't be higher DV than the missiles. The missiles are going to be long, slender shapes but look like trash cans - short, squat things that accelerate at thousands of g's. Engagement range could be 10,000 to 50,000 km... the weapons interactions would be in milliseconds. Passive tracking would be out to 1 light second. And the real flaw is you'd never see your adversary so lousy for television

[@porticoman]

I’ve enjoyed the expanse. It look well researched and realistic in a way many sci fi shows don’t. The fish were escaping from a predator. It’s common to see shoals of fish leaping out of the water if there is something under there trying to eat them.

[@oweirdone1]

Cannot believe you'd put a spoiler for the show in your video title and thumbnail.

[@Tara_Li]

I wish you'd looked at the issues of the fourth asteroid being blown up within just a few Earth diameters. It's really not feasible to turn the entire rock into dust, and even a huge cloud of dust at those speeds would create issues from the heat in the sky.

[@altoticket]

If a huge meteor hits earth and luckily not right on our heads, we would: 1) see the "flash" (visible light, fastest) 2) get burnt from the heat wave, if close enough (irradiated heat, as fast as light but I guess affected by the dampening effect of air density, water droplets in the atmosphere etc) 3) feel the earth shaking (sound speed, slower) 4) be thrown away from the blast (actual shockwave, much slower) 5) experience a tsunami (secondary/tertiary effect) ^ items 3, 4, 5 actually happened in season 4. So, in a distance the fish might even "hear" and react to the infrasonic impact before it reaches us, yes - but the editing made it seem that they would react to the sound pressure of the impact BEFORE one would actually see it, wich does not make much sense. But hey guys, it adds to that bit of suspense/drama that makes for a great story, right? :)

[@thomasb1889]

The fish running away can be explained that the change in pressure which a human might miss triggered the school's panic.

[@ihcterra4625]

I disagree with some of the main premises of the show. Mining wouldn't be the only thing they do in the belt. They would build the foundries and manufacturing facilities out there because zero G means material handling is far easier. Finished products made in the belt would make them incredibly rich even if the mining companies themselves took all the mining profits. Companies could buy the raw materials that were mined without the transportation costs, make parts and assemble finished products. There is also a lot of water ice out in the asteroids. The majority of the asteroids are icy. They would literally have an unlimited supplies of water, hydrogen and oxygen.

[@MrMarcusIndia]

Thanks for pointing out that the sun should be shown as white. Nearly every film and show gets this wrong. I had hoped the Expanse would do better though :)

[@twohorsesinamancostume7606]

You may doubt the existence of psychic fish but that doesn’t mean that they doubt you.

[@uwandumichael1607]

The migration or movement of the fishes away from the direction of asteroid contact is correct. Animals have this instinct of moving away from natural disaster before it occurs

[@tonycrabtree3416]

Good gracious. The comment section is golden. Some high intellect nerd humor that would make Sheldon jealous!

[@RyanRidden]

It's been great seeing all these comments!

[@davidgifford8112]

The Spaceguard asteroid Earth impacter surveillance system from the 1973 novel Rendezvous with Rama (Clarke) suggests this idea has been around for decades.

[@jamesholden5065]

I feel like he means the speed after slowing down from earths atmosphere.

[@nightwaves3203]

Mackerel would sense low frequencies emitted by compression of the atmosphere :) Although they do naturally run in schools and get chased by bigger fish.

[@MartinCHorowitz]

The Meteors shown on the show seem more city killer than country killer size, and the global effects were to big.

[@RyanRidden]

There did seem to something off with the impact size based on the info we were presented. Since the kinetic energy of impact depends on the square of the velocity, it could be possible to make big impacts if those asteroids were going very fast. It might also be interesting to do a back calculation to work out the impact velocity based off the impact and asteroid sizes we see in the show.

[@dapeach06]

@@RyanRidden we did see that a ship was burning at high g before releasing the rock, but the show seems to be playing up the gravity assist trajectories more than engine-assisted acceleration, which is a change from the books.

[@michajastrzebski4383]

@@dapeach06 or it could be both, for even more speed/yield.

[@seriousthree6071]

During such an attack you would want high speed with a near to vertical atmospheric entry as possible to minimise atmospheric abrasion. 150,000kph plus to reduce the effect of climbing out of the Sun's gravity, faster equalling more kenetic energy. The stealth tech would not matter by then, having been burned off. The blast size would come from seismographs and satellite recordings. Result would be a fairly quick accurate estimation of yield in the multi-megaton range.

[@karlfranzemperorofmandefil5547]

Well the scientist didn't really have all the facts. In the books it's said pretty clearly that Inaros had them accelerates to high speed even by epstein drive standards.

[@Bultizar]

IDK if anyone ever realizes that the main problem to space exploration is just producing enough energy. Everything else we basically got. Obviously, except for FTL, as we do not control gravity yet to create space dilation. More specifically negative matter.

[@Wustenfuchs109]

Hi there, first time watching the channel, a fellow physicist. Nice work with a pleasant presentation. One thing though, the scientist on Luna says 30.000kph *on impact* , not on the entrance into the atmosphere. I don't want to calculate the ablation and friction right now to see if it is actually possible to drop from 17 to 8kps just by atmospheric slow down (did it like 8 years ago for meteor parameters in general) but I just wanted to point out that the speed that they zoom throughout the system is not exactly the speed at the moment of impact. I am sorry if this looks like nitpicking, because it might be quite possible that with those levels of energies the speed loss is actually too small, let alone double, depending on a bunch of parameters. I just don't have the time currently for a detailed calculation on this light topic. As I understand, they have good science advisors so someone might have actually done the calculations.

[@ericmcconnaughey2782]

"Fish running away? I take it all back. The Expanse is a terrible show!" Lmao!

[@elliotsmith9812]

Probably the Dolphins from the Hitchhikers Guide.

[@RyanRidden]

They didn't leave the Earth soon enough this time!

[@hd45783]

5:30 Beisides the velocity, I think the blast 'power' is also a little underestimated. 1 -4 MT , at least if they use the TNT- Equivalent , is much higher the the Nuclear Bombs which were dropped during the WW2, but it is lower then e.g. 1st. Hydrogen Bomb Ivy Mike which was estimated to have had a ,~ 10MT - TNT Equivalent and did not have nearly as devastatitng Effects, as depicted. But because they are just guessing it also could be, that their assumptions whould be for a much smaller Asteriod than it actually was ... ^^ BTW Maybe you could make a video of all the little things that are done not quite right aswell ( Like that their are sometimes Sounds in spaces, or that if you are accelarating / deccalerating at the 1G for weeks the distances whould not quite fit...)

[@RyanRidden]

It really does seem like the power was a pretty big underestimate. Great video suggestions, I'll try and get around to them at some point!

[@tedarcher9120]

Nuke megatons are very different from regular megatons or asteroid megatons, as most of the energy from a nuke is radiation which is dispersed on a gigantic area, while an asteroid or a regular explosive produces hot gases which expand and produce much stronger shock wave

[@mb9662]

Can you evaluate the space sci-if show “The Ark” next?

[@Fr0st1989]

You can also see the dude's skin start to burn away as he watches the asteroid impact

[@willyreeves319]

all the debris they create with every battle would make swaths of space extremely hazardous for months to decades bugs me

[@RyanRidden]

It bugs me too! With each fight space becomes more hazardous. Hopefully the future of our space travel wont be so confrontational.

[@JacekNasiadek]

Because of their Epstein drives and the constant-acceleration transfers they use, most spacecraft are on escape trajectories from the solar system, most of the time. So any debris would likely also be on escape trajectories from the solar system. Moving at many tens to hundreds of km/s, they would certainly not linger for decades.

[@willyreeves319]

@@JacekNasiadek even at 1000KM/S (roughly 25 times the escape velocity of the solar system) it would take almost 2 months to travel the distance from the sun to Neptune. but it doesn't just leave it travels the same direction as the ship it used to be. so whatever it's previous destination now has a 10 or 100 or 1000KM/S shower of destruction coming

[@JacekNasiadek]

@@willyreeves319 I agree that any big battle would create a temporary hazard but not a decades-long one, unless it was happening in orbit around something. The Kessler syndrome is such a concern only because the debris is not on an escape trajectory from Earth and even in LEO stays around for much longer than 2 months.

[@willyreeves319]

@@JacekNasiadek fair enough each battle would create a debris field that would be a hazard within the orbit of Neptune for between 1 and 20 months depending on where and what direction and how fast the ships were traveling. how often do such battles happen in the show? seems like there would be a lot of such fields.

[@marknovak6498]

The fish have a genetic memory from the time of the dinosaurs. Case closed. They know to swim away ...

[@sulijoo]

Since this video came out we've had the DART mission which actually changed the orbital period of an asteroid orbiting another asteroid. So in future it might not actually take much to save Earth. Just a nudge.

[@abbaszaidi8371]

Great ending! Just to clear a few things up, the rocks are 30m diameter. And we have witnessed the damage and the MILLIONS killed by the initial disaster of three rocks. But from reading certain pieces of info from the book, I understand several BILLION are yet to die. How many rocks drop in the book then?

[@PHDiaz-vv7yo]

Yeah still waiting on answer here

[@JohnsonJLB]

Not only the fish were psychic, they were computer generated fish that jump out of the water then perform acrobatics and fall back into the water head first. Mullet do not do that. They jump out mostly at a 45 degree and do not move mid-air and fall back in at the same angle tail hitting the water first.

[@andywomack3414]

When silicate/metal asteroid "burns up" in the atmosphere is that an oxidation reaction, or the material being vaporized due to reentry heat? I hesitate to use friction as the heating mechanism as I understand it to be a compression heating effect.

[@Impulset0]

The scientist said, "speed at impact". The asteroid may have had the necessary velocity to penetrate the atmosphere but wouldn't it get slowed down significantly by it? Say enter at 13km/s and impact at 8 km/s?

[@ukaszlampart5316]

Regarding 5:18 In books it was actually wrong in the opposite way. I don't recall exact numbers but it was stated by Amos if I am not mistaken that particular asteroid had energy in range of hundreds of megatons of TNT, which would require velocities way beyond of what could be given to asteroid before it escapes solar system. Maybe pushing some extremely distant asteroid with minimal radial velocity in the direction of sun could do the trick to break this speed limit, but this would be an operation that would take many years to prepare too and many more to execute. In the end both show and books ended up with impossible results which is catastrophic/world-wide destruction (books with impossible/improbable asteroid energy, show with very exaggerated global impact of actual asteroids). But still it is the best Sci-Fi show/books I know.

[@hawkname1234]

OMG. Great stinger at the end. I guffawed pretty loudly.

[@Concreteowl]

The fish are jumping because the water is retreating. There is less volume near the shore because the pressure wave impacting the water surface. The same pressure wave that is dispersing the clouds.

[@Drelam]

I bet the KPH was a mistake either in the script or from the actor reading since everyone is much more use to per hour versus per second and no one on the production crew noticed.

[@Brownyman]

The technology to make the stealth asteroids already exists. It's called "vantablack".

[@Cheese_Boi1986]

you forgot to mention the guys face burning as he looks at the impact and you can pass the fish off as just reacting to a predator

[@Xantaxia]

You've never heard of psychic salmon?

[@MrHaroldOwen]

Only thing that irked me is showing the asteroid belt like some cartoon version. In reality if you were to stand on an asteroid in the belt it's most likely you couldn't even see another one with the naked eye. I know, I know, artistic license to portray the belt but I will always espouse the line from "Hitchhikers Guide to the Galaxy": Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space.

[@Jrd4n]

Lol that last statement about the fish🤣😂

[@mmogaddict]

They probably got the units of speed wrong and meant 30,000 MPH, which would be around the right speed. (still a little slow at 13.5km/sec)

[@PatrickHutton]

Hi I loved the 5 Expanse series. However we're told that the actual impacts on earth were in the region of 150 Kilotons. Yet the portrayed impacts were far far larger than a ground burst nuclear explosion of around 100 to 200 kilotons yield so I suspects that's an inaccuracy.

[@PatrickHutton]

In Season 5 episode 4 the first asteroid impact is described as having a blast of between 200 to 300 Kilotons. However the "news image" implies a blast of hundreds of Megatons.

[@RyanRidden]

I think you are definitely right, the explosions we see are massive!

[@JohnDoe-ib3hr]

This is probably a very stupid question...BUT... say we find a large metal asteroid (500 tonnes for example) how fast could we accelerate it using known technology like ion drives/solar sail/ gravitational assists? it's for a short story about excavating an extremely deep crater in Hellas Planitia using kinetic impactors, with the goal of allowing atmosphere to pool at the lowest point and create an open air ecosystem.

[@EidolonSpecus]

The fish were running from the impact after it happened. The asteroid had already hit moments before we see the light and shockwave in that scene.