recreating the move 'Gravity' in Kerbal Space Program

[Superfluous J]

I know what you mean, but in principle there's no fundamental issue with making a rendezvous using EVA thrusters only as long as you thrust in the right direction. The movie got the direction wrong, but not the situational reasoning.

And the magnitude. One suit just does not - and never will - have the thrust required to do what Clooney's did. They barely have the thrust to do the little tour he took at the start of the film.

- - - Updated - - -

Actually, the supply pod did have the capability of a Mars intercept (The booster for the Taiyang Shen from the Chinese) , the problem was they had less than a month to put the pod together and the only option was to crash land the pod on Mars at about 300 m/s in which the supplies had a low chance of surviving.

That sounds correct to my memory.

[Venusgate]

Clooney falling off the space-cliff, though....

Came here to say: You couldn't re-create gravity in KSP because KSP is too realistic! Imagine!

A few reasons why:

Blowing up a satellite would create such little debris over an area the size of low Earth orbit: The Kessler syndrome would occur... but it would take at least a few months to get that catastrophic.

The Kessler cloud of debris comes around every 90 minutes in the movie. Earth low orbit period is 88 minutes. So the debris cloud is stationary?

Space cliff.

Apparently all the space stations in orbit happened to line up within 100km of each other....Talk about luck!

(To paraphrase): "I'm running low on EVA fuel.... GONNA HAVE TO BLOW IT ALL NOW TO MAKE IT!" (Have you ever tried to do a suicide burn with a kerbal on eva more than 10km away from your intended target?)

/rant

[Enorats]

Gravity suffers from the usual 'Hollywood doesn't understand physics' problem present in practically every movie ever, but the story of Gravity actually kinda works if u mentally redraw the Hollysics scenes in ways that would have been physically possible and produced the same plot results. Apart from the debris-cloud recurrence interval (really, wt...h Sony?), there's nothing else I can think of that couldn't be recreated in a 'that could have worked' way in KSP.

Unlike Interstellar. That movie was a pile of dogdirts. A pile of fresh, warm, multi-coloured dogdirts, with a little US flag in it. Go America!

The Martian had some major nonsense too. Intercept and dock with a supply pod that's not capable of Mars intercept, after/during your Earth flyby burn for a Mars return trajectory, without losing velocity? Ugh...

Seriously, of all the recent near-future sci-fi movies, Gravity is probably the least offensive to the space-physics-enlightened.

Actually - this is mostly false. Almost nothing in the entire Gravity movie made any sense at all. It was mostly all impossible. The other two are - for the most part - reasonably accurate to reality. Obviously the more science fiction-y stuff in Interstellar was nonsense, but on the whole it was solid.

Gravity suffers from a monumental misunderstanding of orbital mechanics, among other things. It treats all points in space as if they exist on a flat plane and are immobile relative to one another. It also acts as though one can move from one point in space to another by simply moving in a straight line, and it ignores the fact that altering your velocity will alter your orbit.

Examples -

If the debris is moving so much faster relative to the things it is hitting (our poor astronauts), then it must be in a highly elliptical orbit (assuming that they are in a circular orbit). Therefore, the debris will not simply "circle the planet" and come back around and hit them again. There would have to be a fairly large number of orbits completed before they would rendezvous again, and if any alterations are made to the orbit of our astronauts then they may not rendezvous ever again.

The Hubble and the ISS are not even close to each other. Hubble is 100 miles farther out and has ~20 degrees lower inclination. Therefore, to make a Hohmann transfer Clooney would have had to eyeball three separate burn windows - a plane matching window to gain 20 degrees of inclination, a retrograde burn to make the transfer, and a prograde burn to match velocities with the station. Of course, one would also likely have to wait through several phasing orbits to reach the appropriate relative positions for the transfer. Starting out with low O2 to begin with.. no. Just no. They would have died far, far before finishing those burns. That's also assuming they have the delta-v required to make them, which they didn't. The bloody shuttle itself couldn't have made that transfer, let alone their little suit pack.

Then, when they finally reach the ISS.. they pretty much broke physics. Not really going into that one, I'm sure you all know the silliness there.

Of course, going from the ISS to Tiangong would require all of the same maneuvers (but in reverse for the most part, as Tiangong is almost as far out as Hubble and at a ~40 degree inclination). Our medical doctor now has to eyeball the burns while flying a ship she doesn't know how to fly. Oh, and she's gonna use the one time use landing jets to complete.. all three burns? Sorry.. I'm thinking she's probably hallucinating at this point. Even Clooney's character should know better. Of course, as it turns out she only needs to complete two of the burns using those one time use thrusters, and uses a fire extinguisher to match velocities with the station. No comment there, aside from.. well, Kerbals don't have those.

It's been awhile since I've seen the movie, but I also seem to recall that Tiangong was deorbiting itself for some reason and can't recall what in the world knocked it out of orbit. I'm pretty sure there was some sort of special magic happening there though.

Our medical doctor was able to fly a Soyuz capsule (which I might even buy, kinda sorta.. astronauts DO train on them as they are the emergency escape route from ISS).. so sure, why can't she just instinctively know how to fly a Chinese capsule too?

The worst part of the movie though? They sent a medical doctor up into space to repair Hubble. Why? Why on Earth would she be placed on that mission as a mission specialist? She's not an engineer.

Edit:

Upon further reflection I will note this about The Martian. If they had a window for a free return trajectory coming up soon, and have planned out multiple manned missions well in advance (they've already got landers and supplies waiting on Mars for those missions).. why didn't they already have another ship and crew on the pad ready to take advantage of the free return opportunity? If there was EVER going to be a time to launch, it would have been then.

Also - why did they take an RTG down to Mars with them? They buried it as soon as they got there (which is silly, as the author later admitted they aren't really dangerous.. he just didn't know that at the time).. so it must not be needed on the main ship for a return journey and it wasn't used on the surface. That only leaves it powering the descent vehicle.. which seems unlikely. I just don't see an RTG being used as a power source for a single use vehicle that is only needed for a tiny portion of the mission. It could have easily run on battery power, solar panels, and/or fuel cells for that short duration.

Edited October 31, 2015 by Enorats

[Superfluous J]

Also - why did they take an RTG down to Mars with them? They buried it as soon as they got there (which is silly, as the author later admitted they aren't really dangerous.. he just didn't know that at the time).. so it must not be needed on the main ship for a return journey and it wasn't used on the surface. That only leaves it powering the descent vehicle.. which seems unlikely. I just don't see an RTG being used as a power source for a single use vehicle that is only needed for a tiny portion of the mission. It could have easily run on battery power, solar panels, and/or fuel cells for that short duration.

I had this problem too, but someone else pointed out that the RTG was not used by the astronauts, but by the unmanned portion of the mission, as the power source to generate the fuel for the return journey. And the burying it was basically red-tape protocol rules made by pencil pushers. That may actually be the most realistic part of the book

[The_Rocketeer]

Obviously the more science fiction-y stuff in Interstellar was nonsense, but on the whole it was solid.

You're yanking my chain, right?

Docking with a spacecraft that's tumbling out of control after a massive explosive depressurisation, yet somehow perfectly rotating around the axis of the docking hub? During an uncontrolled atmospheric re-entry? In an anti-gravity non-aerodynamic lifter craft that just magically returned from the surface? While pulling about 25G?

Also, the whole slingshot-the-black-hole thing. Cos that wouldn't have taken months, at all (not even allowing for the MAJORLY BORKED TIME DILATION).

If anything all we're really establishing here is that Hollywood has no credibility whatsoever when it comes to space. Even Apollo 13.

Edit: also, you're mostly telling me I'm wrong because of the stuff I already acknowledged was wonky. I'm not saying that Gravity got anything right, I'm just saying you could recreate it in KSP without too much trouble - not that you could recreate it in RL. Besides, try recreating that bogus docking scene from Interstellar.

Plus, the Martian... one thing to say.

Ironman.

Edited October 31, 2015 by The_Rocketeer

[Enorats]

Ah, I see. If they sent the RTG with the original lander that sent supplies in the first place then that would make sense. Low power generation over a very long duration mission like that would be perfect for an RTG. However, burying it makes no sense at all really. The author actually admitted that later as he mentioned that when he originally wrote the book he didn't really understand how they worked. He thought that any sort of "leak" in the outer casing would irradiate the surroundings, and that's why the character mentions cracking it open would be bad. In reality the radioactive materials are actually coated in lead, so the RTG is pretty much filled with pellets that don't emit any radiation.. just heat. Now, if you cracked it open and cut the pellets in half.. then you'd have problems.

[LostOblivion]

The question is, how to recreate the moment where Clooney Kerman loses his grip on Sandra Kerman and flies off in defiance of physics...

It could make sense if they were rotating...

[Enorats]

You're yanking my chain, right?

Docking with a spacecraft that's tumbling out of control after a massive explosive depressurisation, yet somehow perfectly rotating around the axis of the docking hub? During an uncontrolled atmospheric re-entry? In an anti-gravity non-aerodynamic lifter craft that just magically returned from the surface? While pulling about 25G?

Also, the whole slingshot-the-black-hole thing. Cos that wouldn't have taken months, at all (not even allowing for the MAJORLY BORKED TIME DILATION).

If anything all we're really establishing here is that Hollywood has no credibility whatsoever when it comes to space. Even Apollo 13.

Edit: also, you're mostly telling me I'm wrong because of the stuff I already acknowledged was wonky. I'm not saying that Gravity got anything right, I'm just saying you could recreate it in KSP without too much trouble - not that you could recreate it in RL. Besides, try recreating that bogus docking scene from Interstellar.

Plus, the Martian... one thing to say.

Ironman.

Actually, no. I'm not. The docking scene wasn't all that bad really. When the port blew, it blew out in such a way that it would have realistically pushed the ship into a spin. The port that they docked with was on the "bottom" of the ship rather than the outer ring, so it would have been rotating around that axis. Maybe not perfectly, but I'll forgive them that - especially given the beauty that was the scene as a whole. The relative motions of the various craft and background scenery was captured perfectly. I'm not sure how many G's they were pulling at that point tbh, they only mention that the craft itself was rotating at around 60 something RPM. The number of g's they would experience on the much smaller lander would be significantly less than that experienced by the ring of the Endurance itself, as the astronauts are much closer to the axis of rotation (thus having a smaller radius in the RPM to G's conversion). The computer was also guiding the ship at that point as well, so there's that. As for the aerodynamics of the lander and how it's engines work.. that's part of the scifi. Can't really comment on that other than to say that it was portrayed as being aerodynamic and having control surfaces, which is more than most scifi ever does. The thing that does get me though.. the atmospheric reentry part. I just don't buy that the Endurance was in such a low orbit that blowing out that airlock (especially as oriented) would have been enough retrograde thrust to de-orbit the craft. Let alone that quickly.. maybe it could knock the periapsis into the atmosphere, but reaching that point would be a long ways off. The other thing that made me giggle a bit was after they docked and used the lander's engines to push the Endurance back up into orbit. Firing thrusters in that manner would have never worked, as the center of mass and center of thrust were not lined up in the slightest and it would have just left the Endurance spinning in space on an axis perpendicular to the one they'd just got out of.

As for the slingshot thing.. that was a bit silly. Though, if I understood correctly the bodies that they visited are orbiting the black hole like a moon orbits a planet. So, it would be like leaving the Mun and dipping in near Kerbin to gain a gravity assist for a quick trip out to Minmus. How long that would take would depend a lot on exactly how large the gravity well of the black hole was. The "moons" of the black hole are obviously orbiting outside the event horizon, but we've no idea how large the radius of that event horizon is. The giant tidal forces experienced on the water moon would seem to suggest a fairly large gravity well, but they never really say. Whatever the case, the smaller the radius of that point of no return they're skimming by is, the quicker the trip would be. It wouldn't necessarily be like a low solar orbit flyby, and could instead be a shorter trip like the one mentioned above. Still, even that is a multiple day trip.

One other thing to note, if it means anything to ya.. Neil deGrasse Tyson praised Interstellar for the overall accuracy of the science they portrayed while he heavily criticized Gravity for being so horribly inaccurate.

Edited November 1, 2015 by Enorats

[The Optimist]

fockin jeb with a RT-5 could do better

[The_Rocketeer]

One other thing to note, if it means anything to ya.. Neil deGrasse Tyson praised Interstellar for the overall accuracy of the science they portrayed while he heavily criticized Gravity for being so horribly inaccurate.

Wonder who bribed him.

I really can't believe you're trying to defend that scene. This isn't worth discussing with you if you're that blinkered.

All 3 movies had enjoyable parts, but all of them were soured by weak science. Honestly, I keep going to see these movies hoping the science won't be trampled all over somewhere, and I always come out of the theatre with those hopes dashed. Interstellar was like Contact meets Signs, and I recommend it to nobody.

God, HOW could you defend that scene?! I'm still boggling over that one...

[Superfluous J]

God, HOW could you defend that scene?! I'm still boggling over that one...

I assume you mean the docking port scene. I defend it easily: Rule of Cool. It was a really really cool scene presented beautifully and it made our hero look awesome. If the rest of the movie was more like that scene and less like the boring pile of ... uh ... not-cool that it was, then it would have been a much better movie. More "realistic"? No. A better movie, though.

There is a fundamental difference between "You couldn't dock those two ships together in that situation" and "You can't get to the ISS from Hubble with 2 people, with the RCS fuel from a single suit." One is a shrug and a "well it's cool anyway let's do it, and plus it makes our hero look BadS" while the other is "Herp I don't know but they said space was like being on a skating rink back in 8th grade so what if they just skated there?"

[The_Rocketeer]

I disagree. We're never presented with the orbits for Gravity, so it doesn't actually contradict the realms of what is reasonably possible. Since the STS program has been reinstated in that film, i.e. it's set in the near-future, why assume that everything is exactly where we have it being today? Knowing stuff about current space missions/orbital altitudes isn't really relevant.

Let's put this another way:

One is 'it can't be done because that's not where we put those things last time I checked'.

The other is 'it can't be done because the fundamental physical laws of the universe and say so'.

[mikegarrison]

Actually, no. I'm not. The docking scene wasn't all that bad really. When the port blew, it blew out in such a way that it would have realistically pushed the ship into a spin. The port that they docked with was on the "bottom" of the ship rather than the outer ring, so it would have been rotating around that axis. Maybe not perfectly, but I'll forgive them that - especially given the beauty that was the scene as a whole. The relative motions of the various craft and background scenery was captured perfectly. I'm not sure how many G's they were pulling at that point tbh, they only mention that the craft itself was rotating at around 60 something RPM. The number of g's they would experience on the much smaller lander would be significantly less than that experienced by the ring of the Endurance itself, as the astronauts are much closer to the axis of rotation (thus having a smaller radius in the RPM to G's conversion). The computer was also guiding the ship at that point as well, so there's that. As for the aerodynamics of the lander and how it's engines work.. that's part of the scifi. Can't really comment on that other than to say that it was portrayed as being aerodynamic and having control surfaces, which is more than most scifi ever does. The thing that does get me though.. the atmospheric reentry part. I just don't buy that the Endurance was in such a low orbit that blowing out that airlock (especially as oriented) would have been enough retrograde thrust to de-orbit the craft. Let alone that quickly.. maybe it could knock the periapsis into the atmosphere, but reaching that point would be a long ways off. The other thing that made me giggle a bit was after they docked and used the lander's engines to push the Endurance back up into orbit. Firing thrusters in that manner would have never worked, as the center of mass and center of thrust were not lined up in the slightest and it would have just left the Endurance spinning in space on an axis perpendicular to the one they'd just got out of.

As for the slingshot thing.. that was a bit silly. Though, if I understood correctly the bodies that they visited are orbiting the black hole like a moon orbits a planet. So, it would be like leaving the Mun and dipping in near Kerbin to gain a gravity assist for a quick trip out to Minmus. How long that would take would depend a lot on exactly how large the gravity well of the black hole was. The "moons" of the black hole are obviously orbiting outside the event horizon, but we've no idea how large the radius of that event horizon is. The giant tidal forces experienced on the water moon would seem to suggest a fairly large gravity well, but they never really say. Whatever the case, the smaller the radius of that point of no return they're skimming by is, the quicker the trip would be. It wouldn't necessarily be like a low solar orbit flyby, and could instead be a shorter trip like the one mentioned above. Still, even that is a multiple day trip.

One other thing to note, if it means anything to ya.. Neil deGrasse Tyson praised Interstellar for the overall accuracy of the science they portrayed while he heavily criticized Gravity for being so horribly inaccurate.

Among all the other ridiculous parts of that scene, let me point out the angular momentum of that huge ringed spaceship with all the mass out on the edges, and then point to the control jets on the landing craft (sized to provide control for that much smaller vehicle). And the control jets are acting at the center of the ring, where they have no leverage. And all the force is being transmitted through a few dogs on a docking ring (apparently made of unobtainium tempered by unicorn tears).

Forget black holes and orbital mechanics, they couldn't even get simple bicycle wheel physics even remotely correct.

- - - Updated - - -

I disagree. We're never presented with the orbits for Gravity, so it doesn't actually contradict the realms of what is reasonably possible. Since the STS program has been reinstated in that film, i.e. it's set in the near-future, why assume that everything is exactly where we have it being today? Knowing stuff about current space missions/orbital altitudes isn't really relevant.

Let's put this another way:

One is 'it can't be done because that's not where we put those things last time I checked'.

The other is 'it can't be done because the fundamental physical laws of the universe and say so'.

The Hubble and the ISS are called out by name.

[Alshain]

I disagree. We're never presented with the orbits for Gravity, so it doesn't actually contradict the realms of what is reasonably possible. Since the STS program has been reinstated in that film, i.e. it's set in the near-future, why assume that everything is exactly where we have it being today? Knowing stuff about current space missions/orbital altitudes isn't really relevant.

Let's put this another way:

One is 'it can't be done because that's not where we put those things last time I checked'.

The other is 'it can't be done because the fundamental physical laws of the universe and say so'.

You don't just 'move' the fully deployed Hubble Telescope even less a fully built International Space Station.

[Venusgate]

One is 'it can't be done because that's not where we put those things last time I checked'.

What part of "George Clooney falls off the space cliff" is not a matter of fundamental physics?

[KerbMav]

And which part of this thread deals with recreating scenes from a movie in KSP - and not with topics "discussed" endlessly across different threads the last several months?!

[mikegarrison]

And which part of this thread deals with recreating scenes from a movie in KSP - and not with topics "discussed" endlessly across different threads the last several months?!

Did you miss the bit where we were discussing that KSP is perhaps too realistic to simulate these unrealistic movies?

[The_Rocketeer]

The Hubble and the ISS are called out by name.

Not in denial, and not part of my argument.

You don't just 'move' the fully deployed Hubble Telescope even less a fully built International Space Station.

Actually the ISS is regularly 'moved', that's why it doesn't fall back to Earth. Even the STS 'moved' it once.

What part of "George Clooney falls off the space cliff" is not a matter of fundamental physics?

There was a space cliff? I must've missed that part.

Anyway, (assuming this is the bit you're talking about) Clooney could have drifted away from Bullock if they were under centripetal force, i.e. 'swinging' around the ISS on a tether. Not what's shown in the movie, I know, but this is what I mean by recreating scenes in a 'that could have really happened' way (e.g. thrusting in the right direction) rather than a 'that's a space cliff he just fell off' way.

Perhaps I've been unclear until now. I am not criticising or praising the scenes or cinematography in these movies - that would be pointless. What I am interested in is whether the story itself hangs together in a logical, physics-friendly way. Does x plus y equal z. To me, the problems of relative orbits in Gravity are moot. If the stations and orbits necessary to make the story possible were in the locations shown in the movie, then the story could happen. On the other hand, the probability of the ship in Interstellar perfectly rotating (and lets be honest, even the lightest wobble would make the entire sequence of events totally impossible) around it's docking port, after an unplanned, uncontrolled explosion and whilst experiencing external forces of drag.. well, that's just never, ever going to be a thing that can happen in the real world (or in KSP).

But I've had enough of stating and defending my case, and in any case most of the replies here are unrelated to the original topic, so rather than drag the debate further into the bushes I'm gonna stay quiet on these points now.

Edited November 2, 2015 by The_Rocketeer

[mikegarrison]

Actually the ISS is regularly 'moved', that's why it doesn't fall back to Earth. Even the STS 'moved' it once.

They don't change orbital planes. All they do is get a little boost to counter the drag from the atmosphere.

Try playing KSP with RSS and establishing an orbital plane. Then try changing it by 20+ degrees and see what kind of dV it takes to do that.

(I think I read that the shuttle had enough orbital dV to change its own plane by about 3 degrees.)

[MalevolentNinja]

Gravity suffers from the usual 'Hollywood doesn't understand physics' problem present in practically every movie ever, but the story of Gravity actually kinda works if u mentally redraw the Hollysics scenes in ways that would have been physically possible and produced the same plot results. Apart from the debris-cloud recurrence interval (really, wt...h Sony?), there's nothing else I can think of that couldn't be recreated in a 'that could have worked' way in KSP.

Unlike Interstellar. That movie was a pile of dogdirts. A pile of fresh, warm, multi-coloured dogdirts, with a little US flag in it. Go America!

The Martian had some major nonsense too. Intercept and dock with a supply pod that's not capable of Mars intercept, after/during your Earth flyby burn for a Mars return trajectory, without losing velocity? Ugh...

Seriously, of all the recent near-future sci-fi movies, Gravity is probably the least offensive to the space-physics-enlightened.

I know you said you're done here, but...

Gravity is pure Hollywood quasi-science tripe. I enjoyed the scenic views the movie presented but that was about the only thing that was realistic. As stated, the orbits of the vessels are no where near each other, and it would make no sense for them to ever be changed. But the biggest issue with Gravity is the entire premise of the movie - there's no way to create a debris field like that that threatens the crew every 90 minutes - it shows no understanding of orbital mechanics whatsoever.

Interstellar in my mind deserves a bit of a pass - they at least tried to use real science. I would be hard pressed to name even one other movie that addresses the physics of General Relativity in a realistic way. Black holes, time dilation, the concept of a curved space-time... I give them a lot of credit for creating a story that exists in the real world of physics as we know it.

The Martian blows the others out of the water for real science. But I am talking about the book, not the movie. The only major plot point of the book that you can criticize for its science is the storm that strands Watney on Mars in the beginning. On Mars hurricane speed winds would not knock you over (due to an atmosphere that is 10% as dense as Earth), you would barely feel them. The author freely admits he took liberty with this in order to set up the story. The rest of the book is solid, really solid.

In the book, Watney only mentions the IronMan solution a) as a joke and because he is delirious from the high g ascent. Blame Ridley Scott for his need to change what didn't need changing. That said, the movie was pretty true to the book, right up to the last 20 minutes where they changed a number of things, all for the worse.

The orbital mechanics in the Martian are especially solid. The author actually worked out all the orbits and transfer burns to coincide with the dates in the book. He only talks about days and months in the book without giving the year, but the mechanics are so accurate that some very smart fans reverse-engineered the year. source

No offense intended, but if the orbital mechanics in The Martian don't make sense to you, it's likely you don't understand what was going on. Again, the book does a much better job of explaining this than the movie. I forgive the movie makers this point, since there's only so much screen time to explain everything. The supply ship was capable of Mars intercept - in order to rendezvous with the Hermes it had to be. But it wasn't capable of delivering that payload to Watney - that would require a precision landing on Mars at sufficiently slow velocity to not destroy the payload. The rocket the Chinese launched was originally going all the way to Mars, they changed plans and decided to use it to resupply the Hermes instead.

Whether you enjoyed a movie or hated it is completely subjective and I would never argue that. The scientific accuracy of a movie, however, is... well... science!

Edited November 3, 2015 by MalevolentNinja

[The_Rocketeer]

@mikegarrison

Yes, I know. Was there a point?

@MalevolentNinja

I don't really disagree with anything you've said, except the parts that contradict something I already said, and in those cases I stand by my view.

I understood everything that The Martian (movie) tried to explain. As I said, I haven't read the book, and frankly discussing anything that occurs in it is irrelevant. If anything, I would say that reading the book disqualifies you from discussing the science of the film because your perspective is compromised.

As you said, whether anyone enjoyed the movies is irrelevant to the science therein contained, which is why I haven't commented on whether I enjoyed them.

Edited November 2, 2015 by The_Rocketeer

[More Boosters]

I thought Martian soil contained perchlorate salts, making it poisonous to plants (and people?)

[Enorats]

As MalevolentNinja said, the movie pretty much follows the book to the letter. It explains the points you're making quite well. The iron man thing was hilariously silly as his CoT was out of line with his CoM, and the storm at the beginning was impossible (author knew that, but wanted to set it up as man vs mars, so he went with it), but otherwise the film was SUPER accurate. It's actually been replicated in KSP, though you have to "cheat" a bit to fast forward to the correct year so the planets are properly aligned. Or just time warp to it.. takes awhile.

Gravity just couldn't be replicated because even if the various craft were oriented as depicted in the film it would still be impossible. Orbital rendezvous just doesn't work that way.

[Enorats]

Upon further reflection.. I do have to admit that The Martian has one major flaw not yet noted. Maybe it is explained in the book.. but I don't think the movie did. Of all the people you could pick, why would you send a botanist to Mars.. a planet with no botany to study? Of course, we know its because he has to be a botanist to have the knowledge to properly prepare Martian soil to grow potaties, but within the context of the story it makes little sense. It's not quite as bad as Gravity sending a medical doctor to repair Hubble, but it still seems a bit odd.

[mikegarrison]

Upon further reflection.. I do have to admit that The Martian has one major flaw not yet noted. Maybe it is explained in the book.. but I don't think the movie did. Of all the people you could pick, why would you send a botanist to Mars.. a planet with no botany to study? Of course, we know its because he has to be a botanist to have the knowledge to properly prepare Martian soil to grow potaties, but within the context of the story it makes little sense. It's not quite as bad as Gravity sending a medical doctor to repair Hubble, but it still seems a bit odd.

If you grow food on your ship or your base (which is not a bad idea, since it can also provide some oxygen), having someone along who takes care of that could be valuable.