I just got done watching Mission to Mars with Tim Robbins. WARNING SPOILERS AHEAD Typical sy-fi stuff. The one part that had me yelling at the screen was when one of the “spacemen, actually spacewoman” went to rescue another astronaut (Tim Robbins). They were wearing jet packs to move around in space outside of their spacecraft. Tim Robbins drifts away from the others and our Hero Spacewoman goes after him. The problem is she doesn’t have enough fuel in her jet pack to make it to him and return to the ship.
Apparently she had enough fuel to reach him, but not enough for the few hundred yard back to the ship. She would run out of fuel midway back. What doesn’t make sense to me in this is they are acting like when moving through space after using your thrusters that you would come to a complete and abrupt stop if you ran out of fuel.
My thought is that she could have reached Tim (Her love interest btw), grabbed him and turn around, aim for the ship and fire your jet pack. Since there is no gravity or air in space there is no friction. As her and Tim are heading back to the ship and run out of fuel, the only thing that would happen is that the jet pack would stop producing a stream. I think that they would continue to “float” towards the ship, fuel or no fuel. Once they were put in motion they would continue that motion until something stopped them.
Is this right? As long as she was able to start the motion toward the ship, they would have reached it. We were only talking a few hundred yards so I would think that the momentum generated by the jet pack should be enough to get them started to the ship. Correct or does Tim actually become the frozen astronautcicle that he becomes in the movie.
I believe you are correct, because that was one of the things in the movie that bothered me too. I saw this when it first come out, in like what 2001 or something?
Objects in motion stay in motion unless acted on by an outside force.
Thrust back towards the ship, and you’ll continue until you smack into the ship.
IOW: there is a movie with a science error in it.
I haven’t seen the movie, but I can imagine a way for the scenario to work.
Suppose hubby was not just away from the spaceship, but actually moving away from the spaceship. Then girlfriend has to make two burns:
[ol]
[li]A first burn to accelerate in the direction of her hubby until she reaches a faster speed than him, so she’ll catch up.[/li][li]Having reached hubby, she needs to grab on to hubby, and make a second burn to kill all of the velocity from the first burn and provide some small momentum back towards the spaceship.[/li][/ol]
It’s entirely possible that she could have enough fuel for the first burn, but not the second, so she could accelerate enough to catch hubby, but not decelerate enough afterwards.
Of course that isn’t quite, “drift to a stop halfway back”. The end state would be them both drifting away from the spaceship (dramatically professing their love for each other in their last moments or some rot).
Perhaps she wouldn’t have been able to match velocity for the return. She would have had to slow herself down after rendezvousing with the other guy, then shifted vectors to get back. Then she would have to accelerate to the same speed (plus a bit to catch up) as the (IIRC) ship she was trying to get back to. If she couldn’t match velocity then once she ran out of juice she and the other guy would basically just fall behind and eventually die.
They didn’t show this in the movie (and, hell, for all I know it never occurred to them the actual issues involved), but if you think of it in terms of different vectors, then shooting off on one vector for a certain amount of time there is going to be a window of acceleration wrt fuel and mass (that would include the mass of the other guy) so that you can rematch vectors with your target. If you don’t hit that window you are fucked. Just because you are in space doesn’t mean you keep accelerating (you don’t), and if your speed isn’t a little bit more than your target you aren’t going to catch up, just drift either at a fixed distance or fall further and further behind eventually.
That’s my thought anyway on trying to make the movie match reality.
Shouldn’t matter, assuming they came from the spaceship in the first place. Everything they’re doing starts from that initial vector as a zero point. (I am not at all sure if I’m conveying this well.) In other words, if she pushes off the space ship, she’s now moving away from the ship relative to the ship. But to an observer motionless with respect to them both, she and the ship are both zooming along forward, except that she’s now zooming along forward and slightly off to the side like.
Oh, the movie was MUCH better at that for dramatic…(the space there is my DRAMTIC PAUSE) effect
MAJOR MOVIE KILLING SPOILER AHEAD – STOP NOW IF YOU DON’T WANT TO KNOW**
He doesn’t want wifey dying to save him, so he takes his helmet off to kill himself so she wouldn’t come after her. She’s upset and apparently if you scream in space, everyone can hear you. So instead of a cute hand holding astronutcicle couple floating in space you just have sad Tim Robbinscicle floating in space forever
it is possible to run out of fuel in space (and believe me it really sucks), and it is possible to have a situation where it is impossible to recover a loved one ia the method you mention. Now if that actually were the case in the situation you describe, well it sounds a bit holllywoodish to me.
I think people misinterpret that scene. It was already established that you cannot just stop yourself–that is why Tim Robbins was floating away. He had too much momentum and could not stop himself after attaching the line to the ship. He was traveling at some velocity away from them. Stopping, starting, and changing your direction all take fuel. His wife did not have fuel to accelerate to an intercept velocity, stop, and then reverse direction to an intercept velocity with the ship. Remember, she had to be able to do this all rather quickly because she had to remain within view of the ship or they would certainly be lost. Also, the further away she was, the more fuel it would take to maneuver back.
I think everyone here gets that. The issue is that the script had her saying she’d run out of fuel halfway back. That sounds like she thinks she’ll be stranded in the desert with a truck with no gas.
The script just should have said she didn’t have the fuel to get there and back - but the writers were trying to show that she could nearly do it, and so said something stupid. Of course, accuracy would have been something like “I only have enough fuel change our relative velocity so that we’re still moving away at 1 meter per hour”. Just not quite the same as the visual of her and Tim stopping just short of the ship.
It’s also possible the suit was smart enough to label the “point of no return” as the point at which the fuel was SO LOW it couldn’t cancel out her forward motion.
But most likely, it’s a science mistake in a movie filled with science mistakes. (Except for the micro-meteor, which was surprisingly realistic.)
