Just Watched Gravity (SPOILERS)

[Hotshot3434]

IMHO the best move to come out this year. Although there are some massive holes in the plot (Hubble being right next door to the ISS) I thought it captured the tone of space perfectly. It is a harsh environment that requires very specialized equipment to exist in. When things go bad they go VERY bad, often leaving you dead, hopelessly stranded in space, or both. To relate to Kerbal Space Program, I once had an accidental high speed collision during a docking attempt that split my space station in half, throwing the only re-entry capable capsule flying away. It was only thanks to a undamaged engine and a few tanks of fuel that the crew was able to board and re-enter with no casualties.

SPOILERS BELOW!!! YOU HAVE BEEN WARNED!!!

I felt the worst for George Clooney's character (I cant remember his name in the movie). I think the worst way to die in space is to be left adrift and alone while you slowly suffocate to death on your own used breath. My third favorite scene in the movie is when he is drifting away and he comments on how beautiful the sunrise is over the mountains (my second favorite scene being when Sandra Bullock turn off the oxygen in the capsule and starts to drift off to sleep and my first favorite being when she is floating in the lake at the end).

What where your thoughts on the movie?

[K^2]

All in all, I think it would be a pretty forgetable movie if it were not for the visuals. But the visuals were there, and they make the movie.

If you have not seen Gravity yet, or if you haven't watched it in 3D, watch it in 3D. It makes all the difference. This is probably the only movie I know where 3D isn't a gimmick. It really makes the experience.

As for the plot, yeah, it's full of holes. The distance they put between the stations, the crippled Soyuz could have made on maneuvering thrusters. And if the separation was great enough to require main engines, there is no way in hell to make it across without guidance from ground anyways. Basically, almost anything to do with physics of actual flight or navigation was wrong. But they still managed zero-G better than almost any other movie, so big props to them on that. And the errors don't distract from the main themes of the movie.

Ah, and I got a chuckle out of Shenzhou basically being a Soyuz with Chinese instead of Russian text on buttons.

[ultimatevirus]

Just saw the movie yesterday and I thought it was pretty good. The physics where indeed off but however they did replicate the iss pretty well. What was also weard is that every country (russia,china,amerika) cant contact their spacecraft but some weard asian mountain dude can. Overall it was a pretty good movie by my opinion.

[Nibb31]

My biggest problem with the movie were:

(SPOILERS! BEWARE OF THE LION!)

Obviously the orbits were all wrong. Hubble, ISS and Tiangong are all on different inclinations or altitudes. Of course, there are ascending and descending nodes where the orbits cross, but the best you could see from one spacecraft is the other spacecraft wizzing across. No way could you actually rendez-vous with it without several days of manoeuvres, plane changes, raising and lowering orbits, etc...

Why was there a spare Soyuz at the ISS and a fully functional Shenzhou at Tiangong? Where did the crews go? How did they leave?

But mostly, and more fundamentally, why did Clooney sacrifice himself? What magical force was pulling him away when they were stationary with the station? Why did he fly off when he detached his tether? Why was Bullock suddenly free to pull herself up as soon as he was detached? And why the heck couldn't he simply pull on the tether to bring Bullock and himself back towards the station? That whole scene was really awkward...

...but not nearly as much as Clooney's entire dialogue!

Edited November 3, 2013 by Nibb31

[Godot]

I assume those are questions every KSP playr asked himself

Another thing:

Sandra ignited the landing thrusters of the Soyuz to speed towards the chinese station and finally, near the station, she thrusted sidewards from the soyuz capsule in direction of the chinese station.

IIRC she left the Soyuz when the landing thrusters already had burned out ... and she used the fire extinguisher to simply accelerate her in a vector sideways of the Soyuz (lets call it y-direction, whereas the direction the Soyuz went is x-direction).

Well, normally one would assume that Sandras speed in x-direction would stay the same as before ... with other words she would fly away parallel to the Soyuz.

In the movie however Sandra (after disconnecting from the Soyuz) suddenly flew much much slower than the capsule (i.e. with a much slower speed in x-direction)

I don´t think the gravitation difference (because Soyuz being a short distance nearrer to earth) would be an explanation for this

[brdavis]

...In the movie however Sandra (after disconnecting from the Soyuz) suddenly flew much much slower than the capsule (i.e. with a much slower speed in x-direction)...

First… it's a movie, so I didn't expect much in terms of scientific accuracy. Second, if you've not read the Bad Astronomy blog on this one, it's probably worth a read. Third, if we really must manufacture rationals for plot points… as she is grappling with the Tiangong, it is clearly undergoing re-entry with some atmospheric drag (because, um… that would happen. Somehow. Maybe magic). If that's the case, she would have potentially had a high drag coif than the Soyuz, leading to a separate (both are decelerating, but she is decelerating more due to a lower areal density).

But… let's be honest, that's really sort of stretching it for a reason. And Tiangong shouldn't have been deorbiting anyway. And the relative closing velocity would have killed her. And the off-axis thrust from a fire extinguisher (a pressurized fire extinguisher on the ISS?) would lead to even worse yaw/pitch issues than shown. And hypervelocity impacts would have a *terrible* time coupling in that much angular momentum to a system like the Shuttle or even the Canadarm. And the lack of blog when a guys head was essentially drilled through. The fire on-board the ISS would have generated internal pressures more than sufficient to do structural damage without impacts (remember Apollo 1?). ISS and Hubble aren't even remotely close (wildly different inclination… and from KSP, we all know different inclination are easy to transfer between, especially from a "low" orbit, right?), and Tiangong isn't there either. No way would you use something like an MMU to be moving anything like that fast with respect to nearby objects. And… And… and…

Clooney didn't have to let go in the first place. They were *at rest* with respect to the ISS. At that point, there were lots of possible solutions.

Yeah, I'm a physicist. There's a lot of science it gets wrong. And (except may, perhaps, for me… a little bit…) it really doesn't dent the movie much. Visually, it's great… and it's still so far outside most people's understanding of reality that it's a fun "oh, I never thought of that" ride.

--

Brian Davis

[Godot]

...

Yeah, I'm a physicist. There's a lot of science it gets wrong. And (except may, perhaps, for me… a little bit…) it really doesn't dent the movie much. Visually, it's great… and it's still so far outside most people's understanding of reality that it's a fun "oh, I never thought of that" ride.

...

That´s something I wouldn´t deny for a moment (and I assume also noone else in this thread).

It was great to see a movie that tried to be at least close to reality and it surely sets a standard for future movies in these regards (although I doubt that we´ll see a movie like this again, in the next couple of years).

[Hotshot3434]

One scene I remember stood out to me as odd was the fire onboard the ISS. I thought in space fire would burn uniformly outward from the fuel source, depriving it of oxygen and snuffing itself out. Have there been any accounts of actual fires in a zero-g environment?

[Godot]

One scene I remember stood out to me as odd was the fire onboard the ISS. I thought in space fire would burn uniformly outward from the fuel source, depriving it of oxygen and snuffing itself out. Have there been any accounts of actual fires in a zero-g environment?

It gets its O2 via diffusion ...

and yep, seems like NASA tested it:

http://motherboard.vice.com/blog/this-is-what-fire-looks-like-in-space--2

[Tygroux]

Just saw the movie yesterday and I thought it was pretty good. The physics where indeed off but however they did replicate the iss pretty well. What was also weard is that every country (russia,china,amerika) cant contact their spacecraft but some weard asian mountain dude can. Overall it was a pretty good movie by my opinion.

Actually that's not that a big plot hole.

It is assumed that ground control use satellite relay for communication (not direct link), and the satellites just get blown up by the kepler syndrome.

I don't know if the space agency have backup plans if all satellites get downed at the same time.

On the other hand, it's a known trick of radio hobbyists to use clouds or the moon as reflector for long-range radio transmission. Require materials and skill, but possible.

[demian_travis]

I watched this movie yesterday. There are some huge plot holes, of course. Clooney was an experienced astronaut and should know that to send the ship down to earth she shouldn't just "point to earth and burn!".

Also, I felt that her movements on 0G were not so natural. It seemed more that she was swimming.

Although it had some problems... WHAT A MOVIE! I give it an 9 out of 10. It has some cliches, but... stunning visuals, great music and work on the audio. Just the fact that the things on space don't go BOOOM all the time is something amazing!

[Hotshot3434]

Clooney was an experienced astronaut and should know that to send the ship down to earth she shouldn't just "point to earth and burn!".

At what point did he do this? I cant remember an instance where he tried to fly toward the earth or when he instructed her to do so.

[brdavis]

It is assumed that ground control use satellite relay for communication (not direct link), and the satellites just get blown up by the kepler syndrome. I don't know if the space agency have backup plans if all satellites get downed at the same time.

Probably the backup plan, if the entire TDRS constellation dropped out, would be "come home immediately"… assuming everybody wasn't dead. You could still use ground transmitters to talk to them however.

The bigger problem is the "Kepler syndrome" (i.e., an orbital debris cascade). My son asked me while watching the movie "would this happen?", and I had to answer with a firm "No, but…". Yes, you can get to a state where the debris multiply rapidly (exponentially)… and that's a serious concern... but that doesn't mean anything like instantly. The movie seems to imply everything going to kibbles and bits in a single orbital period or so - not even the right order of magnitude. An orbital debris cascade would take many multiples (as in "hundreds" or more like "thousands") of the orbital period. And it wouldn't change spacecraft communication in the least… not unless such a debris cascade in LEO would impact Geo-sync orbit, which is where the multiple (yes, they have back-ups) TDR Satellites are located.

Another significant goof here is if the debris stream (from a recent break-up) encountered the shuttle one orbit #1, the chances are incredibly remote that it would encounter it on orbit #2, #3, etc. After all, if the break-up was in the same orbit as the shuttle, it wouldn't have a velocity relative to it… and if it was in a different orbit than the shuttle, they only intersect in two places. So unless you have the break-up event occur in an orbit inclined to the shuttles, but with an identical period, this is not a regularly once-an-orbit repeating phenomenon.

Still bigger problem? Given the likely encounter speeds, they literally never would have seen it coming. Let's say they had a relative encounter speed around 5 kps… if you were lucky enough to see it at a distance of a mile (think about this… given the size of the chunks, do you think you'd spot them at a distance of a mile?), you'd have 0.3 seconds from catching a glimpse to impact. No chance… especially since anything on-coming to you at those speeds would have nearly zero drift velocity across your field of view.

Yeah, the fire in space bit bothered me - because while you *do* get fires in space (Mir had some *serious* issues in this regard), they do not apparently look like that. But, hey, it will visually give the viewer the idea of "danger from fire". At least they didn't resort to "hearing explosions in space". I appreciated that.

--

Brian Davis

[K^2]

Why was there a spare Soyuz at the ISS and a fully functional Shenzhou at Tiangong? Where did the crews go? How did they leave?

They explained that in dialog. Both stations had two ships parked to be used in case of emergencies. That does seem to be a typical configuration. Even during the Shuttle age, I see a lot of pictures with two Soyuz ships parked at the ISS. (for example edit: Hm. Or it might be a Progress. But there are at least four places where Soyuz/Progress can dock, so I don't think it's implausible to have two Soyuz there at any rate.) According to the dialog, both stations were evacuated using only one of the ships, leaving the beat up Soyuz at ISS and a working Shenzhou at Tiangong.

What magical force was pulling [Clooney] away when they were stationary with the station?

I was thinking about that, and it's not as implausible as it seems at first. This could have been due a tiniest amount of force. It really wouldn't take much. So if there was even a bit of angular velocity, he'd be slipping away the way they've shown it, creating just enough tension in the ropes to do what happens next. The way they've shown it is a bit strange, but the situation itself is entirely plausible.

Edited November 3, 2013 by K^2

[Kryten]

They explained that in dialog. Both stations had two ships parked to be used in case of emergencies. That does seem to be a typical configuration.

Soyuz and Shenzhou are only launched both full and with crew (with the exception of a few missions for testing of new variants)-there are always only as many seats available as there are astro/cosmonauts.

[K^2]

Soyuz and Shenzhou are only launched both full and with crew (with the exception of a few missions for testing of new variants)-there are always only as many seats available as there are astro/cosmonauts.

Then, I guess, the only plausible explanation is that not everyone made it. We've only seen a small section of the ISS. Perhaps some modules lost pressure and have been sealed off by the crew during evacuation.

Edit: Or they've only had one pilot, so they decided to take a chance on riding in one Soyuz despite the lack of seats. Re-entry should be surivivable with an overcrowded RM.

Edited November 3, 2013 by K^2

[FenrirWolf]

The force pulling Clooney was just his and Sandra's combined momentum. The cords were slipping off because she didn't have a firm grip on them and the tension wasn't sufficient to stop the combined mass of the two. By letting go of George, the mass of the system was cut in half and the cords could stop her.

Think of it like a kerbal rocket that's at escape velocity but doesn't have enough fuel to kill sufficient velocity to be captured. Now let's pretend the ship has a lander docked to it or something. If you put all your fuel in the lander and let the main ship just float free, you might be able to use that fuel to at least get the lander captured.

Note: this scenario was inspired by my first (and only) attempt to visit Moho. That's pretty much how it played out lol

Edited November 3, 2013 by FenrirWolf

[K^2]

The force pulling Clooney was just his and Sandra's combined momentum. The cords were slipping off because she didn't have a firm grip on them and the tension wasn't sufficient to stop the combined mass of the two. By letting go of George, the mass of the system was cut in half and the cords could stop her.

That's not how physics works. Nibb31's complaint was absolutley valid. There HAS to be a force. It could have been an inertial force from a rotating frame, however, as I pointed out.

[FenrirWolf]

True, that could have been the issue too. Its not like the cords didn't inherently have enough tension since they were designed to hoist a ship as it's parachuting to earth, but they weren't firmly gripped and were sliding loose. Maybe that was because of rotational inertia dislodging them or whatnot.

[Hotshot3434]

Another issue with the physics of the movie was the de-orbiting of the Chinese Station. If I am not mistaken, it would take about 2-3 km/s change in velocity to cause it to enter the atmosphere that deep. Any object that impacted the station with enough force to change the velocity that much would end up blowing the station to bits.

Broken physics aside, still a great movie.

[NASAFanboy]

Had Gravity became 100% ultra pure realistic, it would be just some astronauts running out of air and dying, while the debris floats around in the far background.

Hollywood science, man. It gotta be there for plot convenience.

[SFJackBauer]

Whoever dismiss the entire movie just for its (few) scientifical inaccuracies misses entirely the point. It is a story of survival, perseverance and coming to terms with yourself. It happens the plot is in space, and the writer is fan of space and wanted to give it a proper representation, but that is not the main point of the movie.

[SFJackBauer]

One scene I remember stood out to me as odd was the fire onboard the ISS. I thought in space fire would burn uniformly outward from the fuel source, depriving it of oxygen and snuffing itself out. Have there been any accounts of actual fires in a zero-g environment?

The station fans continualy breath air (and oxygen) into the fire, until the automated fire detection shuts them down.

And yes, there has been fire on Mir. And since we're at it, there has been also a collision in orbit, where a Progress resupply vehicle collided with (also) Mir. The video below contains some footage from inside Mir made in the moment of the collision.

http://www.youtube.com/watch?v=7ZsO7r99L0s&t=27m54s

Edited November 4, 2013 by SFJackBauer

[Galacticruler]

MIR was doomed from day one.

Its a wonder it even survived assembly.

EDIT:

OT:

[K^2]

MIR was doomed from day one.

Its a wonder it even survived assembly.

Lots of electrical tape. Lots. They didn't have duct tape in Soviet Union, but they did have electrical tape and they weren't afraid to use it. Go to Smithsonian. Look at the Soyuz that hangs there. You'll know it's true.