The Expanse Season 2

[TGLS]

I recently started watching the first season. The way the series keeps going on about water really bugs me, especially since it tries to be hard science fiction. Is it really more cost-effective to haul in ice from the asteroid belt than purify water that is already on the planet?

No. Assuming a delta V of 5 km/s, and an exhaust velocity of 20 km/s (comparable to an ion engine), you'll need 284 grams of propellant for every kilogram of water you bring back.

[ORCACommander]

I agree with you on the show going by quickly. I would gladly watch this show for two hours or 90 minutes if they are gonna be as entertaining as this. I like how they are developing all the characters in this show. I actually chuckled when the Captain called Draper a spoilt brat that didn't know the meaning of struggling after she found out that she was basically being used as a guinea pig. Seems like every generation criticizes the next one. I am super excited that they are gonna bring back the Weeping Somnambulist will play a big part in the next episode.
I like Alex too, and his evolution through the two season. How did the computer know that a black ops was landing though? Seems like something you want to keep secrete. Those Martian computers on the gunships must be able to pick up all frequencies even secure ones? But it was brilliant to use that landing point and plot a random course to seem like space debris so he could land the craft.

the roci is still able to communicate on secure martian comm bands, the martian navy was sent a message to stay clear of a specific ship that was entering the no fly zone.

@tgls mars needs water because for the teraforming project there is an insufficient mass of it. The roid colonies and space stations need water and other frozen volatiles because they are operating at a constant loss of resources. Further while officially the engines in the expanse move ships at the speed of plot it has been hypothoized that they are actually fusion torch drives, https://youtu.be/JWZqp0QoXcw

[MadAmosMalone]

Weird that you posted that particular video. I just watched it only a day before. Coincidence? Or influence of the protomolecule? You be the judge.

[TGLS]

Mars needs water because for the teraforming project there is an insufficient mass of it. The roid colonies and space stations need water and other frozen volatiles because they are operating at a constant loss of resources.

Okay, but why did they build colonies where there isn't lots of water (Or have the colonies been around so long that they are running out of water?)

Further while officially the engines in the expanse move ships at the speed of plot it has been hypothoized that they are actually fusion torch drives, https://youtu.be/JWZqp0QoXcw

Well, if they have so efficient engines, why haven't they moved the colonies to the water?

Just working out the math again: Delta V of 5 km/s, and exhaust velocity of 300 km/s (a fairly efficient drive, go substantially higher and you're looking at a starship), you'll need 16 grams of propellant for every kilo of water you bring back. However, ships this efficient are pushing out fusion products for propellant, so now you need to pay for it both ways, which means you need 33 grams of propellant for every kilo. Also, the fusion fuels are probably more expensive than the cheap hydrogen other rockets can use.

[Crowley]

The water situation just doesn't add up to me. For example, it is mentioned early on that all the ice in Ceres has been long since excavated. That would equal roughly one seventh of all water on Earth by current estimates. I feel like the writer wanted to make a statement about limited resources and sacrificed scientific accuracy for it.

Come to think of it, why doesn't Earth operate a major water exporting business? They could use a lower sea level, for one.

[TGLS]

Come to think of it, why doesn't Earth operate a major water exporting business? They could use a lower sea level, for one.

It'd be crazy expensive for one thing. A billion dollars buys 200,000 kg of water in low earth orbit (today). The average American uses about 375 kg of water per day, for reference. Then you need to get the water where it's going; at 300 km/s exhaust velocity, it would cost 16 grams per kilo from Earth to Mars ($80 extra), and 38 grams per kilo from Earth to Ceres ($190 extra). With less effective rockets, i.e. 20 km/s, 285 grams per kilo to Mars ($1425 extra) and 755 grams per kilo to Ceres ($3775 extra).

[MadAmosMalone]

I dunno about all that. All I know is my suspension of disbelief is a lot less with this show than with most any other SF show I've seen (that's set in space that is.) There's no magic tech systems like artificial gravity (except for the whole thing with Eros and Miller) or transporters or FTL and everything seems a lot more grounded in reality as we understand it. Add to this an interesting mystery and engaging characters and I definitely put this show in the "win" column.

That said, I do have a few problems with the show's depiction of its reality but some of these are explainable. The whole scene with Alex piloting the Roci through the Jovian moon system seemed really cartoonish to me. I listened to the episode podcast and watched the "Inside the Expanse" video and got a little better understanding of why that was shown the way it was. The show has to convey what Alex is doing and do so in a way that is entertaining as well as gets the point across what he's trying to accomplish. I think it would have been better to depict that on maybe an instrument panel or something because the way they did it makes it look like all the moons of Jupiter are just within a few miles of each other.

I also hate to give 'em a "check minus" for something else (especially in the same episode) but that incinerator Holden used to torch the box with the "proto hybrid" inside just looked really "Star Trek" to me. This show can definitely do better.

Still a really enjoyable show for me. I loved how Holden took one look at that thing looking back at them from outside the station and he wants to go hunting it. Speaking only for myself, I think I would have run home crying for momma if I had seen that thing.

[lsgreg]

I am curious how Holden thinks Amos and him are gonna take a porto-hybrid on when a squad of UN soldiers and Draper's Squad was taken out by just one of those things. There may be more than one to top that. But the Proto had the element of surprise and they know something about its capabilities

I guess I have to admit that the piloting through the system is a little far fetched, but slingshot dang it! That is hard core Sci Fi right? I am a former AF jet mechanic and can't they have a joystick and a throttle to pilot a Spaceship in a Sci Fi show? Other than the Delta Flyer from Voyager!

[MadAmosMalone]

Oh definitely hard core scifi! I didn't say the science of what he was doing was off, just the way they showed it was. It's just a matter of scale, that's all. That is to say both space and time scale as I also think it might take Alex at least a couple of days to reach Ganymede from Cyllene, especially taking into account the roundabout way he had to get there (to say nothing of Cyllene having a retrograde orbit). Of course, here I am talking like I know anything about science when I get lost trying to calculate F=MA

Yeah in one of the videos there was an interview with Cas Anvar where he talked about wanting a joystick for the Roci. He said something to the effect of him not getting what he wanted but what he got was at least close.

I'll hafta re-watch the episode again but I think I remember Holden told Amos to go with Naomi. He wouldn't have to ask this Amos to do that since I think I'd rather gargle with carpet tacks than try to take on that monster outside the station. No, I think it's just gonna be Holden and Prax and maybe Alex out there dealing with the "proto-sapien."

[lsgreg]

Yeah, I forgot that Amos said he was going with Naomi. It even shows in the next episode preview that he was body-slamming someone in a crowd. You are right.