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Realistic Science Fiction: What did Interstellar/the Martian get wrong?


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If you're picky about it, the list can be extremely long.
A quick search about it on Google (or whatever) will give you an idea.

But on the other side, a 100% realistic space mission would be incredibly boring to watch as an entertainment.

Edited by Gaarst
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Interstellar wasn't very realistic at all.

The Martian was much better. The only two things that made me cringe were:

Spoiler
  • The movie ignored that martian regolith is sterile and highly toxic. Nothing could grow with such high perchlorate levels and even if they did, those potatoes wouldn't have been edible.
  • The atmospheric pressure on Mars is too low for winds to be strong enough to form a violent storm.

Andy Weir was aware of the above facts, but if he had removed those two points, there wouldn't have been much of a story.

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1 minute ago, Rakaydos said:

The big one in The Martian is the first storm- the author acknowledges it as a plot device to set up his man-vs-nature story.

There are a couple of things in the beginning of The Martian that are hard to swallow, even with the suspension of disbelief.

The storm is one of them. Not the storm itself. Yes, it's unrealistic but I can roll with that. What bothers me is that apparently these storms exist and they are powerful enough to topple over the launch vehicle, but somehow the MAV for ARES IV never got hit by it in the years (? at least by the time Watney gets there it has to be years) it spent on the Martian surface.

The crew immediately going back after reaching Hermes is another one. The entire story-arch and various sub-plots hinge on orbital mechanics. To paraphrase: “you can't just fire the engine and go to another planet. There's a small launch window and you require a precisely calculated trajectory.” And yet the book and the movie suggest that they basically take off leaving Mark behind, reach Hermes, punch the "Ignite" button and went home.

 

 

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9 minutes ago, Kerbart said:

And yet the book and the movie suggest that they basically take off leaving Mark behind, reach Hermes, punch the "Ignite" button and went home.

They did though. The Hermes had ion drives, which slowly accelerated the ship over months, instead of doing precise, short-duration burns like most other spacecraft. I found a video showing the Hermes' orbital trajectory here: http://www.galactanet.com/martian/hermes.mp4

Source: https://www.youtube.com/watch?v=gMfuLtjgzA8
It's at around 14:26.

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5 minutes ago, Kerbart said:

The crew immediately going back after reaching Hermes is another one. The entire story-arch and various sub-plots hinge on orbital mechanics. To paraphrase: “you can't just fire the engine and go to another planet. There's a small launch window and you require a precisely calculated trajectory.” And yet the book and the movie suggest that they basically take off leaving Mark behind, reach Hermes, punch the "Ignite" button and went home.

 

The book explained it as the return window already closing- every day they waited would make the return cost more DV, and the 30 day mission was planned to leave a reasonable reserve for earth return. But as far as they knew, there was no scientific reason to stick around, the didnt have a MDV or MAV to explore the surface anymore, and the space taxi's meter was running. The bosses at mission control basically said "get back with as much left in the tanks as possible so we dont need to send as many refueling flights."

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The mars air pressure is so low he didn't need hab canvas at all, and probably would have been better off without it.  He should have just cut all the structure off the hull plates he possibly could to minimize weight, and covered himself (in a space suit) with the hab canvas.  This would have protected him from flying debris and bits of martian dust coming in at high speeds.  And he didn't need to fly.

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The martian storm (if the winds reach 400kmh as its mention) can blow up a person with a space suit without problem.

We already had this discussion and I prove it with the help of  Peadar1987.

 

400kmh wind on mars is similar to 150kmh in earth due its low reynolds number and the lower friction due its gravity plus dust in the air that increase the density.

About Interstellar mistakes..  take care on those ones too.. there are less than everybody thinks.

 

Edited by AngelLestat
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6 hours ago, SargeRho said:

The SSTO landers in Interstellar are the only thing I can actually think of, it required a booster rocket to put the Ranger into orbit the first time, but somehow they can land and take off from planets repeatedly.

I can forgive that, but only on the premise that they were carrying extra fuel and supplies for the mission, and that it makes no sense to start off with anything less that full tanks.

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9 minutes ago, ChrisSpace said:

Both Interstellar and the Martian kind of completely ignore radiation

I checked the doses the other day.  "1.8 millisievert per day during the transit phase.. Radiation doses are less than half after planetfall because the bulk of the planet itself - you can approximate it as a flat plane protecting you from exactly half - protects you.

Without opening up my copy of the book, I don't remember how long it was, but it was something on the order of 2-3 years for the Hermes crew. That's 2k sievert. 1 Sievert means a 5% chance of getting fatal cancer. Assuming linear response, it's a 10% chance.

And the martian occurs a few decades into the future, and the crew who do develop cancer wouldn't get it til decades after that. So their odds are survival are better, still.

A flaw in my numbers is that the Hermes traveled very close to the sun.  That trajectory would have greatly increased the crew exposure.   I also don't know how much shielding they had - it would have made sense to fuel their ion engines with liquid hydrogen, and then place the crew quarters in between the hydrogen tanks.  That of course only helps until you are almost dry of fuel, which they would have been...

The Hermes in the book was a high performance spacecraft.  It has quite good TWR for nuclear electric propulsion.  The only way they could have gotten that kind of performance was to minimize mass everywhere they could, especially in the nuclear reactor power source...

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The engines in Interstellar were so overpowered it's absurd. Given the time dilation difference between Endurance and Miller's planet it works out that Endurance's orbit has a velocity of about 33%c and Miller's planet orbit the blackhole at 55%c.

So you are talking about a craft that can hold 3 guys and a robot (and pretty roomy interior), do a burn that charges the craft's velocity by 22% the speed of light, then land on a planet with 1.3G and atmosphere, then take off back into orbit, then change the craft's velocity by another 22% the speed of light to dock with Endurance again, all in a single stage. If you could build engines that good you wouldn't need to know how to manipulate gravity to lift space colonies into orbit, you will just build heaps of those engines and strap them to the space colony itself.

With The Martian beside the storm the only thing that stood out to me was reducing hydrazine inside his hab to make hydrogen for burning. Hydrazine is pretty nasty stuff, about as awful as chemicals we've specifically invented to kill each other with (VX, sarin, all that good stuff). I'm pretty sure handling the stuff and bringing it indoor to react in a jury rigged reactor will kill you pretty quickly.

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53 minutes ago, Temstar said:

The engines in Interstellar were so overpowered it's absurd. Given the time dilation difference between Endurance and Miller's planet it works out that Endurance's orbit has a velocity of about 33%c and Miller's planet orbit the blackhole at 55%c.

So you are talking about a craft that can hold 3 guys and a robot (and pretty roomy interior), do a burn that charges the craft's velocity by 22% the speed of light, then land on a planet with 1.3G and atmosphere, then take off back into orbit, then change the craft's velocity by another 22% the speed of light to dock with Endurance again, all in a single stage. If you could build engines that good you wouldn't need to know how to manipulate gravity to lift space colonies into orbit, you will just build heaps of those engines and strap them to the space colony itself.

The time dilation wasn't because of speed. It was because of gravity. Miller's planet is so close to the black hole that it almost touches the event horizon. The Endurance is much further away from the black hole, because it waits at the Lagrange Point L2.

9 hours ago, ChrisSpace said:

Both Interstellar and the Martian kind of completely ignore radiation

Look at Watney's skin at the end.

And the Endurance in Interstellar is probably so high-tech that it has a magnetic shielding or something like that.

Edited by Geher
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The time dilation wasn't because of speed. It was because of gravity. Miller's planet is so close to the black hole that it almost touches the event horizon.

 

It's both, time dilation on Miller's planet is caused by both the effects of special relativity (because it's orbiting at relativistic speeds) and general relativity (because it's in a region of highly curved spacetime). Miller's planet must be orbiting at relativistic speed because that's what "orbiting near the event horizon" means by definition.

Quote

The Endurance is much further away from the black hole, because it waits at the Lagrange Point L2

 

The Endurance is definitely not at L2 point of Miller's planet because Miller's planet has 130% earth's mass and it's orbiting a supermassive blackhole with millions of solar masses (hence the supermassive part). Because the ratio of mass is so extreme any Lagrange point would be so close to Miller's planet that there will be negligible difference in time dilation.

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46 minutes ago, Temstar said:

The Endurance is definitely not at L2 point of Miller's planet because Miller's planet has 130% earth's mass and it's orbiting a supermassive blackhole with millions of solar masses (hence the supermassive part). Because the ratio of mass is so extreme any Lagrange point would be so close to Miller's planet that there will be negligible difference in time dilation.

But the movie says that the Endurance is at L2. They chose to go from L2 and then aerobrake to save fuel.

I'm no physicist, but it would be cool if somebody else here could calculate how big the time dilation would really be.

Here's a german article about some things that Interstellar got wrong.

Edited by Geher
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But the movie says that the Endurance is at L2. They chose to go from L2 and then aerobrake to save fuel.

Nah nah they said and I quote directly

"Instead of taking the Endurance into orbit around Miller's planet which will save fuel but we'll lose a lot of time, what if we take a wider orbit around Gargantua parallel with Miller's planet outside of this time shifter here"


Didn't say L2 or anything. For all we know the plan was probably go into a Gargantuan orbit wider than Miller's planet's orbit. Then have the Ranger burn directly for Miller (not hohmann transfer orbit), land, then burn directly back towards the Endurance. After all Endurance will only be in this orbit for an hour and the Ranger is equipped with magical relativistic rocket engines.

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As an embedded systems engineer, I hated that scene in interstellar where they "figure out" the probe sent to that water planet was time dilated.  Dumb, dumb, dumb, dumb, dumb.  Here's why :

1.  The telemetry stream from that probe, if there is time dilation, it's going to undergo a massive frequency shift.  To decode the data at all you basically have to use the exact time dilation factor in your digital receiver.

2.  Uh, timestamps?  Any telemetry protocol anybody has ever cooked up, for just about any system used in anything, includes the local time for the computer on the machine sending telemetry in each and every frame.  So once you compensate for the frequency shift so you can decode the message, you would immediately spot that the messages were extremely close together in time.  And no, you wouldn't think "internal clock failure", if that happened, you wouldn't get any telemetry at all.

3.  Frame timing?  If you expect to get 1 telemetry frame every 10 minutes, and you get 1 every month, you just might clue in that there is a gigantic timeshift...

There's just no way they'd send their only manned follow-up mission, carrying the literal hope of humanity onboard, to a planet where the telemetry data says "bottom of a black hole, yo"

4.  For that matter, why didn't they spot the time dilation when approaching the planet...Wasn't there a telemetry link between the Endurance and the lander?  Handwaving over the insane velocity changes needed to go into a black hole gravity well like that, or the Hawking radiation storm off the black hole that would kill everyone in instants, you'd think you'd notice real quick there's a time shift..

5.  As a side note, where did all the water go on Earth?  Closed system, yo.  It's totally possible to do things that would dirty all the water on earth, but it would still be here....and engineers could devise filters to clean it so you could use the water again...

Edited by SomeGuy123
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12 hours ago, AngelLestat said:

The martian storm (if the winds reach 400kmh as its mention) can blow up a person with a space suit without problem.

We already had this discussion and I prove it with the help of  Peadar1987.

 

No, you didn't prove it. You used numbers that imply a person on Earth can't walk up a 30 degree slope.

Also worth noting, is while that discussion was just assuming 400 km/h winds, its worth noting that those winds only occur at the poles at the end of the winter, as the frozen CO2 sublimes and releases lots of gas. The Martian took place very close to the equator, where the winds would be much less. Also, I don't recall when it took place, but I doubt it was the right time of the martian year either.

Interstellar... a master of realistic SF? LOL replace it with Gravity... which is more realistic, as long as you don't mind assuming some alternate timeline where various things were launched on different orbits from what they are in reality (after all, you have to assume an alternate timeline to even have a shuttle flight)...

Then to get the orbit intersecting a debris field every 90 minutes at relatively low velocity, you basically have to assume a debris disk/ring that is slightly inclined relative to your orbit, and that your orbit is eliptical enough that you intersect the disk at perapsis and not apoapsis (though there wouldn't be enough time for it to form a disk...

or you could assume its just a "cloud" with an orbit inclined relative to your orbit... that you intersect at AN/DN... and you're in a high enough orbit that An and Dn are 90 minutes apart.

... and the sequence of shots of the earth do not correspond to any possible orbit... but you'd have to look very carefully and match the shots of what part of the earth they are over at any given time to realize that.

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1. - 4. Yeah, sometimes we have to exchange our brains for a box of popcorn to enjoy a movie. :wink:

5. I cannot remember anything about missing water, but wikipedia talks about crop blights and I do remember that something killed of crop after crop until they had nothing left they could grow.

Everything being dry and the massive dust storms are probably the result of wide spread desertification. The water is still on the planet, just less evenly distributed. There maybe even areas where constant rainstorms make farming impossible.

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3 hours ago, Geher said:

Here's a german article about some things that Interstellar got wrong.

Here there is a book that all critics should read before write silly things.

I also explain some of these points in this old post:

 

4 hours ago, Geher said:

The time dilation wasn't because of speed. It was because of gravity. Miller's planet is so close to the black hole that it almost touches the event horizon. The Endurance is much further away from the black hole, because it waits at the Lagrange Point L2.

Look at Watney's skin at the end.

And the Endurance in Interstellar is probably so high-tech that it has a magnetic shielding or something like that.

That is not accurate, is a rotating black hole, miller´s planet orbit is at 0.45c.  This place millers planet at more than 3 Au from the singularity, the even horizon has a radius of 1Au.

 

46 minutes ago, KerikBalm said:

No, you didn't prove it. You used numbers that imply a person on Earth can't walk up a 30 degree slope.

Also worth noting, is while that discussion was just assuming 400 km/h winds, its worth noting that those winds only occur at the poles at the end of the winter, as the frozen CO2 sublimes and releases lots of gas. The Martian took place very close to the equator, where the winds would be much less. Also, I don't recall when it took place, but I doubt it was the right time of the martian year either.

I prove it :P, and the friction coefficient that I took was correct, the problem that you picture in your head the wrong example, there is not a perfect 30 degree slope with grave and very thin dust on earth which does not sink over your foot to change the angle in where you can compare with your experiences. And even if we rise the friction coefficient, 100km wind in earth can make you blow away if something hit you like in the movie.

You can doubt about the 400kmh wind on mars equator everything you want, I dont have that kind of evidence and I assume it will be very weird. But under those numbers, you can't denied that is very accurate even if the same writer dint knew it.  

Quote

Interstellar... a master of realistic SF? LOL replace it with Gravity... which is more realistic, as long as you don't mind assuming some alternate timeline where various things were launched on different orbits from what they are in reality (after all, you have to assume an alternate timeline to even have a shuttle flight)...

Read the book. It has its flaws as any movie who is more interested in the story than in their 0.5% science followers, but most of them are not the ones that everybody thinks.

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14 hours ago, SomeGuy123 said:

A flaw in my numbers is that the Hermes traveled very close to the sun.  That trajectory would have greatly increased the crew exposure.

I am not sure. Radiation is proportional to 1/r², but the orbital speed increases as well (at ~1/r, but that's a rough approximation); thus they stay that close only for a comparably small amount of time. Hence the amount of radiation might be comparable to that of the other parts of the trajectory (still not good if it heightens cancer chance by another 10% per person).

But it could be that more radiation in less time increases the risk significantly, e.g. due to the body having no chance to regenerate. Then they are screwed without a shield of some kind.

Edited by ZetaX
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