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Doctor Who - The Waters of Mars - John C. Kirk

Nov. 15th, 2009

10:40 pm - Doctor Who - The Waters of Mars

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Tonight I watched the latest Doctor Who special: The Waters of Mars. Actually, I only found out about it a few hours before it started, when I looked at the Sky TV listings online; the last time I checked the BBC website, they just said "Coming later this year". Mind you, it's been a while since I last watched anything on the BBC channels, so they may well have been promoting it for a while. Anyway, I thought it was a decent episode: not my favourite, but they had a couple of interesting ideas.

The basic idea here is that the Doctor turns up on Mars, and wanders over to visit the colony. It turns out that this is in fact the first human colony on Mars, but he's visited on the day that it's going to be destroyed. He seemed surprised by this, so presumably he didn't intend to visit that day. So, either the TARDIS is acting up again, or he just hit the "I feel lucky" button and didn't bother checking the display when he landed.

Initially, it looked as though the colony was destroyed by a meteor crashing into Mars, but later on they revealed that the base commander used the self-destruct option to detonate a nuclear bomb. (Am I just hallucinating, or did anyone else see the rock crash into the planet early on?)

The key theme of this episode was that this was a pivotal point in history, so the Doctor couldn't interfere. I've mentioned this idea before (in 2006 and 2008), and they've gradually been making it more explicit: basically, the Doctor isn't as reckless as he looks, because he knows what changes he can get away with. That's fair enough, but I think there's a bit of wiggle room here. In fact, about halfway through the episode I said "No, I don't accept this." Future history shows that the colony was destroyed, but presumably no bodies were found. So, why not use his TARDIS to take everyone away before the explosion, then drop them off in the future (after they've left their legacy) or on another planet (where they won't be able to contact Earth)? The Doctor mentioned Pompeii, and I had the same reaction to that episode: if people are doomed to die, that's a pretty good opportunity for him to recruit new companions. Speaking of companions, it was Donna who nagged him into rescuing Caecilius, so I wondered whether that was the deeper point of this episode, i.e. showing that he needs someone around to influence him, otherwise he'll just stand back and watch the tragedy unfold.

As it turned out, he did do something similar, although he sent a remote-controlled robot off to fetch the TARDIS and bring it back; I was thinking that he could just walk there after he left the base and then bring it back himself. No need to hurry, since it's a time machine: as long as he's far enough away not to die in the explosion, he could then go back to just beforehand, without any risk of meeting himself. This would have enabled him to save extra people, rather than leaving them to die, but never mind.

As a related issue, I don't think the dramatic escape quite worked. Basically, we saw the self-destruct clock tick down to one second left, while everyone was still outside the TARDIS (and a couple of people were sitting on the ground). Then we saw the base explode, then we saw the TARDIS materialise back on Earth. So, in that single second, all four of them were able to get into the TARDIS, the Doctor was able to program the controls, and it was able to dematerialise? No. I'm sorry, but that's just stretching credibility too far. Again, this is where my proposed method would have worked better, since we could have seen the "original history", with the remaining crew alone in the room watching the timer hit zero, then the explosion, and then seen the revised history when the Doctor goes back to change it. That way, you get the same dramatic tension ("oh no, they're all dead!"), which would actually seem more plausible when the lead character is absent, but you also get the last minute rescue.

Once they did all leave Mars, why go to Earth in the "present day" (2059)? That's going to mess up history a lot more than taking them to another place/time. Then again, as I've said before, I sympathise with Johnny Maxwell's attitude: "Everything we do affects the future! It always has. It always will." It was interesting to see the Doctor taking a Judge Dredd attitude towards the timeline ("I am the law!"), and it was fairly clear that this was intended as a character flaw rather than a happy ending.

Ending on a positive note, I liked the way that the characters tried to give a decent medical description of what had happened to the infected people (e.g. cracked skin around the mouth) rather than just saying "They're zombies!" And I definitely agree with the Doctor that cycling around the base would be a good idea. Bromptons in space!

Anyway, I'm looking forward to the next episode (on Christmas Day), and there's not too long to wait for that now.

Comments:

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From:gaspodog
Date:November 15th, 2009 11:23 pm (UTC)
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I didn't watch this, but I have started wondering about the bicycles on Mars concept for some reason.

Physically speaking, wouldn't your ability to exert force on the pedals be limited by the local gravity (about 0.38 g)? After all, if you tried to stand on the pedals to go quickly, you'd only have 38% of your weight on Earth in terms of downward force. Friction on the bearings would be somewhat reduced, but I'm not sure this would compensate. Your mass is unchanged, so you'd still need the same forward force to produce the same acceleration as on Earth, thanks to good old Newton and his second law. Maintaining a given speed would be easier though, due to the reduced mechanical friction.

I'm guessing you might end up having to use lower gear ratios, in order that you don't end up just pushing yourself off the bike. With lower gear ratios, you would be limited in your ability to go fast whilst still maintaining a sensible pedaling speed.

Perhaps to compensate for this you could have bigger wheel diameters (to maximise linear speed at the tyre for a given angular speed at the bearing), though I think you reach a point where it becomes impractical to make bike wheels much bigger. Maybe you could have a giant rear wheel and a normal (and hence hand-steerable) front wheel.

Some sort of recumbent might work - as then you would have a backrest to push against when pedalling.

I've almost certainly gone wrong in some of my assumptions, and I'm definitely over-analysing the situation. The part of my brain that is still a physics teacher got curious though... :)
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From:johnckirk
Date:November 15th, 2009 11:46 pm (UTC)
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Hmm, interesting question. Gravity didn't seem to be an issue in the episode (they were sprinting around inside the base rather than bouncing), and I forgot that Mars is different to Earth in that respect.

I very rarely stand on my pedals, mainly because I'm worried about damaging the bike (I've already on my 3rd right pedal). If someone is seated, I'd guess that it would be slightly harder to push down but slightly easier to pull your legs up, so it should even out. SPD pedals would probably be a good idea, so that your feet stay attached, then it's just a question of how strong your legs are, i.e. you wouldn't be drifting away. As long as the bike actually stays on the ground, you shouldn't be wasting any of your energy.

More generally, if you were in freefall ("zero gravity"), maybe some kind of tramline system would work? In Gladiators, the final obstacle course included a "handbike" (1:30 to 1:40 in this video): presumably you could do something similar with your legs rather than your hands.
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From:gaspodog
Date:November 15th, 2009 11:56 pm (UTC)
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Even if you were seated though, the limit on the downward force you could usefully apply would presumably still be approximately equal to your weight, as if you apply more force than that you'd end up pushing yourself up out of the seat.

SPD pedals would certainly be a help, as you could make use of pulling as well as pushing to generate useful work. Perhaps also some sort of tethering system whereby your shoulders are anchored to the bicycle frame, as this would allow you to push down harder.

I recall the Gladiators handbike thing. It works fine in our gravity because your weight pulls you down. In zero-g, every time you pulled on a 'pedal', you'd also end up pulling yourself toward the device. Unless you simultaneously pushed with the other hand, thus balancing the forces. Actually, it might be easier if there was a pole attached to the moving section with loops for your feet, again allowing you something to push/pull against and keeping you tethered in place.
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From:dynix
Date:November 16th, 2009 09:39 am (UTC)
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"So, why not use his TARDIS to take everyone away before the explosion, then drop them off in the future (after they've left their legacy) or on another planet (where they won't be able to contact Earth)?"

Yep.
and the second I thought of that I switched off from the entire epiode. They really do need to start taking into acccount alternative solutions an 8 yer old could guess.
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