Inside the Spaceflight of 'The Martian'

benonemusic writes: Science writer Michael Greshko partnered with a team of scientists and engineers to explore the spacecraft and mission plans in The Martian (novel and movie), down to the rescue plan itself. Incorporating the help of Andy Weir, the novel's author, he comes up with a calendar of events for The Martian, explores the hazards of going back to save Mark Watney, and explains how a real world interplanetary spacecraft would pull off a rescue maneuver.

Comments

Fun Movie, Not Future Reality

[Frosty Piss]

It's a movie > Maybe a fun movie, but a movie. Nothing in it real, and the big stuff is not even remotely possible, or for that matter, what it may be like if insanity prevails and we trip to Mars. It's fun for engineers to traipse off into fantasy with movie directors, but most of the time it's just that, fantasy, like Doctor Who...

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

I like how Dan Kois of Slate put it: "The Martian the movie is science fiction. The Martian the book is fictional science."

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

The only thing really impossible about the whole mission plan is the budget. All the technology needed is here, it's just that wars are more profitable.

Of course as for the events transpiring later, there were some stretches of reality, e.g. the sandstorm on Mars, at 0.6% Earth pressure would feel like a light zephyr.

But the only thing that sets the missions to Mars apart from reality is several billion dollars.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

The ending was ludicrous. It wasn't a question of suspension of disbelief, it's just flat-out stupidly impossible, but not as bad as Gravity.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Here comes legions of Pedantic morons to tell us all how it just can't be true!

Re:Fun Movie, Not Future Reality

[SharpFang]

Not entirely impossible, just unlikely. There was a lot that could go wrong, and very likely to go wrong. The deceleration through blowing the airlock would most likely send Hermes spinning instead of decelerating, the opening not being a precise nozzle but a random hole directing the air outside at a random angle. The rocket would most likely be unbalanced after such heavy strip-down, sending it spinning again.

OTOH everyone overestimates the "one chance" they had at the encounter.

You're moving 12m/s away from the target.
To reach 12m/s at 2mm/s^2 you need 6000s or 100 minutes. That puts the target at 72km distance.
Now give it a chase. Accelerate for half of that distance, decelerate the other half. 6m/s top speed, average 3m/s relative speed. That's another 6.6 hours.
Mark would need to spend about 8 hours waiting for Hermes to smoothly make a perfect rendez-vous after failing the initial encounter. There's no time pression of time like with suborbital trajectory - they are both on escape trajectory. Hermes would get a little off Purnell Maneuver trajectory, but 72km offset and 12m/s error is practically nothing for this kind of mission. The whole panic was simply unnecessary.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

> Not entirely impossible, just unlikely.

No, it was impossible. Spacesuits are only pressurized at about 5 psi. They made it look like he was a punctured compressed air tank.

If he cut his glove, it would push his hand back a little bit, he might might even move a few meters (more likely go into a spin) and he would pass out shortly thereafter. No "Iron Man," sorry!

Re:Fun Movie, Not Future Reality

[KGIII]

I just watched this tonight with a lady friend. I was bored enough to browse /. on my phone for a little while. Then she grabbed my hand and whispered that I'm supposed to be watching the movie. So, I watched the rest of it. I'm not really impressed - it just stretched the imagination.

Sort of spoiler alert ahead - not this movie but another movie...

I'm reminded of another silly movie that I saw but the name escapes me. It was fairly recent and a guy gets tricked into time traveling space mission stuff and comes back (through the power of love) and returns home in time to witness the death of his now elderly daughter. The whole thing was silly and the big thing about it was that 'it doesn't violate any laws of physics.' Which, while true, is about as applicable as saying that the idea of a God doesn't violate physics - pretty much an entirely meaningless sentiment. I mean, you could probably state the same thing about the Matrix movie.

Anyhow, it was akin to that in my mind. It was kind of a "sure but I'm not seeing anything close to reality here" type of thing for me.

I shan't spoil The Martian, however. If you like nice graphics, not bad acting actually, and some neat special effects then it's worth a few dollars I guess. I wasn't able to get immersed in it and I didn't want to see it in 3D. (I should look to find out if they have prescription 3D glasses, they give me headaches.)

I'm not sure if I'd recommend saving it to watch at home. Honestly, unless you've a decent home theater then I don't see any reason to even bother. I'd say it's marginally watchable on the big screen simply because it's on the big screen. There's no compelling reason to watch it at home, however. It's just not worth watching for the story line. The acting was good, I'll give it that. I do really enjoy Damon quite a bit. Sean Bean is also pretty good and has an excellent history of quality work.

Anyhow, I think it's documentary time. I need to clear my head a little. The movie wasn't horrific but I was seriously hoping for better. It might have helped if I'd read the book or done more than watch a single trailer before agreeing that it was worth a shot. I'd probably give it a 3 out of 5 stars (where 2.5 is average). So, yes, it's agreed - we'll find a documentary. What can be more fun than sitting in a small hotel suite, eating left over Chinese, with another human being, and watching educational television?

*sighs* Yes, yes I do need professional help. ;) The worst part is I'll probably be poking at my laptop while doing so.

Re:Fun Movie, Not Future Reality

[AchilleTalon]

Pretty much silly declaration. There is a lot of unknowns starting from sustaining life and keep sane the astronauts during the journey to Mars.

But I agree the whole budget thing is just even more silly than the rest. Who would spend taxpayers' billion dollars to save Matt Damon (again)? Be realistic, we let people die here on Earth for much less than that. Let him die once and for all. The astronaut is of no value once the mission is over.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Only necessary in the way that it makes a better ending for a movie.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

There are some incredible documentaries.

Man on Wire

Grizzly Man

Deep Water

A Class Divided: aka Blue Eyes Brown Eyes

Tim's Vermeer

The Challenger Disaster (More a dramatization, but accurate and very very good)

Enjoy! :)

Re:Fun Movie, Not Future Reality

[KGIII]

I've seen all but the A Class Divided and Tim's Vermeer. I'll take a look, thanks. We've watched a few now, it's pretty early in the morning but it has been a fun night.

This one was interesting:
https://www.youtube.com/watch?...

It's about an escaped convict in Australia who lived among the aboriginal people back when white folk were new to the continent. His name was William Buckley.

Another that was interesting was:
https://www.youtube.com/watch?...

That one was about the war in Afghanistan, right at the very beginning, when a bunch of Taliban were taken prisoner and revolted and caused a bunch of mayhem. It too was more interesting than I'd expected.

I only watch documentaries normally. If I had to average it out then I'd say I watch maybe a non-documentary once or twice a month, sometimes less than that. I don't watch them to learn anything, not anything deep. I don't even retain what I learn for very long but I do learn enough to be passingly familiar with a variety of subjects.

To me they're entertainment, I find them more entertaining than I do a thriller, an action movie, or something similar. I grew up watching many WWII and Korean War documentaries and longer expose-type news shows on the on-going Vietnam war. So, it's really been what I prefer for a long time - my whole life really. I think one of the greatest things in life is access to all these documentaries in an instant. 'Tis glorious. I usually watch one during the day and one at night as I sleep though I'll often leave some playing while I sleep.

Anyhow, thanks for the links and suggestions. I'll certainly look into them and likely watch them. I don't do the 'documentaries' you see on cable these days (Pawn Shop shows are not documentaries - nor is rummaging in somebody's attic) but I prefer stuff that is probably considered dry by most people's views. I'll take a gander and see.

Re:Fun Movie, Not Future Reality

[KGIII]

Wait, no, I've seen A Class Divided. LOL Not bad, mostly confirmed what I'd expected. People suck and don't really like admitting their faults.

Re:Fun Movie, Not Future Reality

[umghhh]

It all applies to all of us, you (and me of course too) including.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

GP poster back, glad you liked the suggestions, even if you've seen most of them. I found Tim's Vermeer to be absolutely fascinating, but see how you go.

Another strong recommendation would be Paradise Lost though it's a bit depressing. I watched the documentary before they were released, and it was tough going, but perhaps it's a different experience watching it now knowing that they've been released and are no longer on death row.

I also enjoyed Touching The Void, which really hits you afterwards when you realise these two guys couldn't be put in the same room for the interviews to make the documentary. The tension between them must be incredible.

Thanks for the recommendations, I'll check them out, and not just because I'm Aussie :)

PS: Yes, unfortunately people do suck.

Re:Fun Movie, Not Future Reality

[umghhh]

So how big part of population shares your approach?

Re:Fun Movie, Not Future Reality

[umghhh]

we are on /. after all we are pedantic morons and we are proud of it. As with everything else pedantic morons have their use too. Not necessarily in area of leadership or ideas embedded in fiction of any type tho.

Re:Fun Movie, Not Future Reality

[KGIII]

Paradise Lost was actually really good. The whole justice system was a complete and total failure. There are people who are still convinced the kids are guilty. I've seen a couple of things about their situation at this point. It really tends to piss me off a bit but I watch stuff like that anyhow. I kind of bounce from subject to subject and I'll then consume a whole lot of documentaries about it.

A fairly unknown but very good series is, "What the Ancients Knew"
https://www.youtube.com/playli...

I've not seen Touching the Void. I'll look for it at Hulu or Netflix first. I end up pirating a lot because they're often not reasonably available. They really need to set up a VOD service and I'll happily pay for that just for the ease of finding stuff. They could make it better than a simple search result but I'd settle for, and pay for, just that. As you can probably guess, I wasn't kidding about watching only documentaries. That is my entertainment. I don't watch any regular television, don't even have OTA hooked up at home or even know if I can get it and have only turned on the TV in this particular hotel room once to try to catch the local news.

I have no idea if there's more people like me - you may be one. I've seen some online documentary aggregate sites so I'm guessing there are others who at least appreciate them at times. It's almost, exclusively, what I watch however. There's surely others or there wouldn't be the many aggregate sites though those often include things I'd have a hard time interpreting as documentaries. I don't even really consider "Modern Marvels" to be much of a documentary - sort of a low-end documentary like "How It's Made." I like those but they're just barely in the documentary group by virtue of being educational in nature as opposed to entertainment-intended. Maybe I should call them soft and hard core documentaries with fetish documentaries being reserved for 'talks' like the TED Talks. (Which I also tend to throw in their with the genre, again because of their intent and not necessarily their format.)

So we've got soft and hard core and fetish documentary groupings. I can't say I've ever put any thought into this and I have someone new in my hotel bed (they're dressed - I touch on this in last night's journal entry) so I wasn't able to stay sleeping for very long. Thus my thought process might be slightly more screwy than normal. Anyhow, I'm sure we'll need more definitions and sub-genres than the proposed but I'm pretty open to consuming any of the three.

Hmm... If I have to let Pawn Stars, Antiques Roadshow, and crap like that in the genre then I'll have to call those 'fluff documentaries.' I'll consume them but only if I must or they somehow manage to capture my attention. As I usually have a wide variety of choices (and watching them as entertainment means I can watch them more than once and still enjoy them as there is still much to learn) then I don't usually encounter that situation.

WWII In Color
Battlefield (all varieties)
Soviet Storm
WWI In Color
WWII in HD (not to be confused with the first)

Those are all excellent. I held out, for a while, but even the Science Channel and Military Channel became unwatchable. I think The Military Channel has changed its name? I simply stopped watching, even on rare occasions, after a while and finally just canceled my satellite subscription. I've since taken the receiver down and caulked the holes. That was quite a while ago. I don't see me ever going back. It was actually fairly novel for me to have had the service in the first place.

Re:Fun Movie, Not Future Reality

[Quarters]

Thanks for being the self-centered asshole who feels it's OK to fire up his phone screen in a darkened theater. Why should you have to bother to park your selfishness for 90-120 minutes and let the scores of other people see a movie in peace, right?

Re:Fun Movie, Not Future Reality

[RoccamOccam]

I just watched this tonight with a lady friend. I was bored enough to browse /. on my phone for a little while. Then she grabbed my hand and whispered that I'm supposed to be watching the movie.

Wow - you just casually admit to this? For the sake of others, please never do this again. There's a reason that theaters run the little public service announcements about turning off your phone before the movie. This should be a standard question on a test designed to identify sociopaths: "If you bored while watching a movie in a theater, do you a) suffer silently, b) leave the theater, or c) ignore the rest of the people in the theater that have paid to watch the movie and pull out your phone."

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

If you want to go all out on understanding modern history then this series called The Cold War is an absolutely must. I am assuming you're from the US? If you watch this series from start to finish you really must have an open mind about the actions of the US, and the way the rest of the world has seen the US as an active aggressor for almost 100 years now. Even without an open mind this documentary series is excellent watching due to the top-notch quality of the research, and the far reaching scope of the interviewees, including many world leaders, both US and Soviet presidents as well as Fidel Castro. Absolutely excellent watching.

I'm not sure if I can categorize documentaries in a similar way to you. For me, it's about quality: research, interviews, story telling, narration. If a documentary hits all of those points then I consider it to be high quality and will watch it.

Re:Fun Movie, Not Future Reality

[KGIII]

Oh it's on silent and I'm in the very back and we were pretty much off by ourselves in the corner. Not that many people were there to see it, actually. Most went to the 3D version I suspect. I'd never leave it on any volume level or even on vibrate.

Re:Fun Movie, Not Future Reality

[KGIII]

You're aware that I was in the back, corner, pretty much alone (just the two of us over there), and it was on silent, right? You'll get over it - watch the movie and not me.

Re:Fun Movie, Not Future Reality

[KGIII]

I've seen that and, absolutely, I realize the US didn't win WWII on its own and many other things - like nuking the Japanese might not really have been the reason that they surrendered. From what I can tell, they're all a little biased and some are outright dishonest. I usually turn the latter off and will mentally try to correct for the former. I think I'll make it a point to watch that series again - it was pretty damned good.

Re:Fun Movie, Not Future Reality

[AchilleTalon]

At least Buzz Aldrin.

Re:Fun Movie, Not Future Reality

[AchilleTalon]

And just take this single fact the astronauts heading to Mars will be constantly and permanently striked by cosmic rays since Mars doesn't have a magnetic field and its atmosphere is much less dense than Earth's atmosphere. In case you don't know, when cosmic rays strikes you eye globe it produces flashes you can see. In short, these poor guys will have hard time to sleep. This is just one thing among a pile of others that would turn anyone unsane here after a couple of months.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

"both US and Soviet presidents" should read as "including presidents from both the US and USSR."

Re:Fun Movie, Not Future Reality

[Quarters]

You realize that light bounces and people have peripheral vision. People shouldn't have to 'get over it'. If you are so self centered as to not care about other people, including the woman you were with, enjoying a movie then you are an asshole. If you are so attached to Slashdot that you can't go the length of a movie without checking it, get your ass up and go to the lobby.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

He's only here to brag about having been at the back of a dark movie theatre with his "lady friend" who "grabbed him" and "whispered in his ear", while he simultaneously tells us all how much smarter he is than we are at space travel.

Real fun guy, he is.

Re:Fun Movie, Not Future Reality

[KGIII]

Well then I'm an asshole. You'll adjust. Compared to those talking on their phone, speaking loudly, and generally also ignoring the movie I dare say I was fairly well behaved but I am indeed an asshole and you'll adjust. However, I think we've already established (long ago, actually) that I'm an asshole. The only thing left for you to do is to adjust. If a small light emission from behind you is disconcerting then you might have ADD. If it's more bothersome than the guy in front yelling on his phone then you might have OCD. If it's worse than the number of times people had phones go off then you might be surrounded by assholes and outside is not a place you should go.

Re:Fun Movie, Not Future Reality

[pepty]

No worse than the way people in zero-G in the Hermes flew in curves instead of straight lines.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Well then I'm an asshole. You'll adjust.

That attitude just makes you even more of an asshole. I'm amazed nobody shouted you down. Note to self: never go watch a movie in the US.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Your 'lady friend' doesn't count, right?
That's exactly why I do not go to the theater. Every insensitive, narcissist(re:asshole) has an excuse to justify their behavior. You know, special circumstance for special people. Meh.

Re:Fun Movie, Not Future Reality

[KGIII]

I don't think anyone noticed but the person I was with and she thought it was funny. I think she just wanted to hold hands, otherwise she might have just let me be. I'm an asshole but, you know, if someone had noticed and looked displeased or bothered then I'd have stopped. I'm not THAT much of an asshole.

Re:Fun Movie, Not Future Reality

[KGIII]

She thought it kind of funny/quirky. Also, I'm pretty sure she just wanted to hold hands. Seriously, nobody noticed. If anyone had noticed or even indicated a marginal distaste then I'd have turned it off. I'm an asshole but not that much of an asshole.

Re:Fun Movie, Not Future Reality

[Archfeld]

LOL no, if I find you do interfere I'd just complain to the theatre folks and they will throw you out, the same way they do to guy in front who won't stop talking to his companion. I am in the theater to watch the movie as with most other people, if you can't restrain yourself for 2+ hours then you need to stay at home and watch on Netflix...

Re:Fun Movie, Not Future Reality

[KGIII]

And yet that's never happened. Funny that. However, I certainly agree that I'm an asshole. On a more serious note, nobody noticed - it's not like I was anywhere that bugged people. Well, she noticed but it turns out she just wanted to hold hands. (She's still here, at any rate.) I was kind of surprised at how few people were in the theater - it was a Regal in Buffalo. They all went and watched the 3D version. If someone had even slightly indicated displeasure then I'd have certainly stopped - while I am an asshole I'm not that much of an asshole. I'm usually pretty perceptive too. I also wasn't holding it up and waving it about or anything. It was down between my knees and automatically dims in the darkness. You'd probably have had to work to notice as we had the entire row to ourselves and it was the furthest row back. Not even the usher complained - probably because it bothered nobody and was on silent.

It's tempting... Man is it tempting. I mean, hell, you're offering free life skills assistance, right? So far you've been willing to call me an asshole, without really knowing much, and that's certainly true. So you're willing to be brutally honest, perhaps perceptive, and you seem to be convinced you have all the answers to what is and isn't socially acceptable behavior. Boy have I got a wall of text and some questions for you. You have no idea how tempting that is... ;) Tempting indeed. I mean, you guys helped me pick my favorite Linux distro. You've given me advice on investing (albeit not intentionally). You, meaning Slashdot in general, are generally smart and insightful as a whole. In fact, I'm on my current adventure, in part, due to some advice from a person here on Slashdot.

Alas, I'll think I'll pass for now. I also need advice about buying a boat. I don't know anything about boats but I'm told I could invest a small amount and make a tidy sum on a resale assuming I'm willing to park some currency for a while. You don't know anything about boats, do you? It's a big boat, it has sails and a motor and stuff. It's in Barbados and has engine and cosmetic issues and the insurance had lapsed. It's huge, like 130' huge, and the price is pretty high as is the estimated repair cost but the resale value's pretty high too - a 200% profit would be reasonable but the turn-around could be a couple of years (or more - I don't know) as the market isn't that strong currently, or so I'm told.

I mean, yeah, if you're giving out free advice... *shrugs* It can't hurt to ask, right? I really should do a funny Ask Slashdot style journal post.

Re:Fun Movie, Not Future Reality

[Archfeld]

If you'll read I did NOT call you an asshole, or any other sort of a name, but some resident troll certainly did. I merely stated that if you bothered my watching the movie I'd not argue but ask the theatre staff to deal with you. Personally I don't see a problem if you wanted play cards as long as it didn't distract me from the movie. As for life assistance I don't recall giving any of that either, I am hardly they proper source for that, it would be like the kettle trying to remake the pot. As for Linux distros I use a BSD as a firewall and a Ubuntu for a media server but my regular laptop I use windows 7 for directX games. I have not been all that happy with the Ubuntu though, so in the spirit of your post I'll ask you what distro YOU use. Note : I am too lazy to deal with constantly changing wine. Now onto boats, the only thing I know is they are VERY expensive to maintain, as is consistently said, a boat is a hole in the water in which to throw money. PS I think at that length it is not a boat but a ship. All said and done cheers and have a good day :)

Re:Fun Movie, Not Future Reality

[KGIII]

My bad, I'd confused you with another. ;) And I misread - it's 70 feet. I still think it's pretty huge but I have no idea what boats sell for or whatnot. I'd just be buying it to invest and make money. I'm not sure where I got 130 from. :/ I blame "distractions."

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Dumbshit crackhead mods, there is nothing trollish or flamebait about this post!

Stop modding shit down just because you don't like it!! Jesus.

Re:Fun Movie, Not Future Reality

[lucien86]

No a silly movie about Mars is any movie where at some point they find Martians or an ancient dead Martian civilization.

About the only realistic way that we could find aliens on Mars is the way it happens in Total Recall - where an ancient alien has left an object on Mars as a SETI marker for humanity to find. (or if we find billion year dead bacteria) While the film is just sci-fi the scenario is actually half-realistic or at least possible. Mars is a good place to leave an object because Mars is orbitally and geologically stable and not a lot happens there. The problem of course is that the probability of actually finding such an object would be/is still at least billions to 1 - unless we had some special way to detect it. A needle in a million haystacks..
The statistics that there is such an object somewhere in the solar system are about ~ 100:1 and - the most likely places to find one might be Mars or the Moon or even Pluto..

Re:Fun Movie, Not Future Reality

[SharpFang]

oh, wait. One more thing. As ludicrous you might think the "iron man"...

The only thing really impossible about the whole mission plan is the budget.

A mission like Ares 3 could have been launched today, if NASA budget had never been cut after the Apollo program.

Now, if one of the astronauts was left behind, stranded, getting him back to Earth would be far trickier and quite likely impossible. But the Ares 3 mission plan was sound and doable. It's the events triggered by completely impossible storm that were a serious stretch.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Air pressure differential?

Makes me think of the pneumatic tubes in Futurama. :)

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

What about the light pollution... Turn it off or don't go to the movies jerk.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Here's a hint: you are not special. The same rules apply to you as everyone else.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

What? They flew straight in zero G, grabbed a bar, aimed themselves into a tube, and then let the acceleration of the rotating section drag them "downward" to the outside of the ring. That's also why they had "gravity" in spots on the ship.

Rotational physics. It's a thing.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

What? They flew straight in zero G, grabbed a bar, aimed themselves into a tube, and then let the acceleration of the rotating section drag them "downward" to the outside of the ring.

You don't feel any acceleration from the rotating section unless you're in contact with it. Unlike gravity, it has no effect on you while you're in free fall. There's no "field" to accelerate you, only hard walls and floors.

Rotational physics. It's a thing.

Yep. You should learn it!

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Sorry, I really have to post this as Anonymous Coward, but I'm just passing by. This thing of not extracting the phone from your pocket is totally ridiculous BS. I've just come back from a cinema where practically everybody kept crunching popcorns from huge buckets, digging the last crisp from the deep corners of plastic bags and sucking straws for the last drops of some fizzy drink. It was like watching a movie in the company of a herd of rodents. And you have the balls to annoy me with this silly phone light thing? How's it possible not to realize how stupid this is?

Re:Fun Movie, Not Future Reality

[SharpFang]

Your point breaks at "grabbed a bar". No, they didn't grab any bar anywhere where the rotation would act as "simulated gravity". They appeared as if sucked into the tube, which would work with air moving there; moving in freefall they won't be dragged anywhere. They might crash against the wall of the tube and then be dragged "downward", but as long as they don't touch any of the structure, the virtual centripetal force doesn't appear.

Re:Fun Movie, Not Future Reality

[Anonymous Coward]

Read a book or two about screenwriting, and you'll understand why you can't just present your story to the audience and have it accepted.

You have to sell your story, and in a film like The Martian, that means making the science believable.

it's a movie and "made up"

[turkeydance]

what we see are the shadows on the screen.

Re:it's a movie and "made up"

[umghhh]

Better than what this old fart Plato had. Now we can share our shadows on the wall of the cave and see it all while drinking beer and eating popcorn.

Are and storms that fierce on Mars?

[peter303]

I know they have sandstorms, sometimes dense enough to hide the surface. But with an atmosphere that never exceeds 2% the density of Earth's, can it blow people down and topple spaceships?

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

I know they have sandstorms, sometimes dense enough to hide the surface. But with an atmosphere that never exceeds 2% the density of Earth's, can it blow people down and topple spaceships?

You're not watching a science documentary. So a little bit of artistic license is good.

Re:Are and storms that fierce on Mars?

[ClickOnThis]

I know they have sandstorms, sometimes dense enough to hide the surface. But with an atmosphere that never exceeds 2% the density of Earth's, can it blow people down and topple spaceships?

The short answer is no.

Re:Are and storms that fierce on Mars?

[Jhon]

If you are in low gravity, you can pick up much heavier objects and throw them at your friends. Getting hit with a 1 lbs rock will do less damage than getting hit with a 100 lbs rock -- gotta love how mass works.

Is there enough wind to MOVE huge rocks and people in space suits? Not really. But explosive decomp in lower gravity could possibily toss a 180 lbs human out the door and a decent rate of speed. And if there was a sudden stop (slamming in to a cliff or another habitat module), that could be pretty damaging. Maybe instead of a sand-storm there should have been an explosive decomp.

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

Hmm but you still have to be strong enough to move the 100 lbs rock, while picking it up from the ground maybe much less work, it won't get thrown with as much momentum, therefore total energy can be around the same. It is the energy that does the damage, gotta love how mass works.

But when talking about acts of god, like weather, well the totals forces involved there can be "astronomical" :)

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

If you are in low gravity, you can pick up much heavier objects and throw them at your friends.

You might be able to pick them up more easily, but throwing them isn't going to be.

Getting hit with a 1 lbs rock will do less damage than getting hit with a 100 lbs rock.

You don't say... Also a 1 lbs rock will do less damage than getting hit with 100 1 lbs rocks.

Re:Are and storms that fierce on Mars?

[SharpFang]

Andy Weir explained in one of the interviews that it was the only point where he used his artistic license against hard science. "I wanted Mars to deliver the first punch". He said he could have done this differently, but he wanted this to be Nature's fault, not a human shortcoming.

He stayed true to science best to his ability the rest of the time. Not that he didn't make any mistakes - he made quite a few, but none of them were intentional violations, just his lack of universal knowledge - or developments that happened after he wrote the book.

To name a few:
- water content in soil, making Hydrazine burning moot.
- Chlorides content in soil, making it totally unsuitable for plants and harmful to health, unless purified.
- raw potatoes being merely "awful" while in reality they are quite poisonous.
- hydrazine reaction heat being neglected (someone calculated it would heat up the Hab to 400C).
- space radiation being handwaved away by "Hab is radiation-proof" while it's an inflatable structure.

Re:Are and storms that fierce on Mars?

[Irate Engineer]

- raw potatoes being merely "awful" while in reality they are quite poisonous.

Wow, they sell 5 lb bags of raw potatoes in the store! What a reckless thing to do! Amazing the personal injury lawyers haven't jumped on that!

Seriously, properly grown potatoes are harmless, raw or cooked. However, being nightshades, if potatoes are not hilled properly the ones near the soil surface that are exposed to sunlight will turn green and produce solanine, a glycoakaloid poison. I grow potatoes in my garden and just make sure to toss any potatoes that have any green on them.

Fresh young potatoes from the garden, sliced thin and sprinkled with a little sea salt are pretty darned tasty, but eating nothing but potatoes would start to suck ass pretty quickly.

Re:Are and storms that fierce on Mars?

[Irate Engineer]

- hydrazine reaction heat being neglected (someone calculated it would heat up the Hab to 400C).

Yes, if the calculation assumes a completely adiabatic Hab, and the heat release occurs quickly. A trickle of hydrazine in a Hab in contact with the ground with ambient temps around 0 deg. C doesn't seem farfetched to me.

Re:Are and storms that fierce on Mars?

[SharpFang]

Well, a tested method in the army here, to get a few days off e.g. missing some heavy exercises, was to eat a couple raw potatoes. Guaranteed heavy diarrhea and a bit of fever.

They aren't so poisonous as to "eat one and you die" and I guess a few slices surely won't hurt, but a few potatoes eaten raw just cause a severe indigestion. I believe it's completely apart from solanine, simply human digestion is incapable of dissolving any bigger pieces of them properly.

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

Well, a tested method in the army here, to get a few days off e.g. missing some heavy exercises, was to eat a couple raw potatoes. Guaranteed heavy diarrhea and a bit of fever.

Well, if you're eating chunks of potato instead of diced, sliced or mashed, I can see maybe how that could upset your digestion, especially uncooked.

Re:Are and storms that fierce on Mars?

[KGIII]

Well, I assume they're chewing them and not swallowing them whole.

Re: Are and storms that fierce on Mars?

[Anonymous Coward]

Perchlorate in the soil, not chloride

Re:Are and storms that fierce on Mars?

[wisnoskij]

But, presumably, when the air is filled with sand it is a lot denser than standard Martian atmosphere. They do not appear to account for this change in atmo density, so I am not sure about their calculations.

Re:Are and storms that fierce on Mars?

[steveha]

- space radiation being handwaved away by "Hab is radiation-proof" while it's an inflatable structure.

At least the story is internally consistent: because the Hab is radiation-proof, radio waves don't go through it, which is why Mark Watney has to go outside the Hab just to check his email. (Actually, I think he ought to have strung a network cable; he cheerfully did more difficult tasks than that at various points in the book. But then the plot complication caused by going outside so often might not have occurred.)

When I like a book or movie I tend to try to come up with explanations of anything I wonder about. My explanation of how the Hab is radiation-proof: a superconducting magnetic shield. Only protects against charged particles though...wouldn't stop gamma rays. How common is random gamma radiation on the surface of Mars?

Here's an article about spacecraft using magnetic shields:

http://home.web.cern.ch/about/updates/2015/08/superconducting-shield-astronauts

P.S. I've also seen reviewers complaining that Mark Watney oversells the dangers of the radiation inside an RTG. In the book at least he is joking around a lot and using imprecise terms such as "box full of radiation" so I don't accept this as a valid complaint.

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

The worst are the exclusive OR storms.

Re:Are and storms that fierce on Mars?

[Rei]

There were far more major glaring errors than that. I managed to read about a quarter of the book, needing something to bang my head into on almost every page. No, I don't want to turn this thread into yet another "rip on the terrible 'science' in The Martian" thread, so I'm not going to start yet another "list" like I've done the last times the book came up on Slashdot.

Honestly, with how much he screwed up the science in general, I doubt Weir's "I did it for artistic license" excuse about the dust storm. It comes across as a post-facto to explain away one of his screwups that was getting the most complaints.

Re:Are and storms that fierce on Mars?

[Rei]

At least the story is internally consistent: because the Hab is radiation-proof, radio waves don't go through it

Yet another Weir misunderstanding, confusing all forms of radiation as if they're the same thing. If you want to block radio waves with as little mass as possible, you use metals. If you want to block streams of charged particles with as little mass as possible (the actual goal), you use hydrogen-rich materials, ideally with a borated inner liner. Weir has a history of misunderstanding radiation and confusing all types as if they're the same thing - check out his rant about how horrificly dangerous the radiation from an RTG is ;) Speaking of that...

I've also seen reviewers complaining that Mark Watney oversells the dangers of the radiation inside an RTG. In the book at least he is joking around a lot and using imprecise terms such as "box full of radiation"

He's not "joking around", the rant is like a page and a half long, describing it as vastly more dangerous than Pu-239, with a long line of superlatives for how to describe its incredible "danger". He talks about how it gets glowing hot with radiation and extends that logic to meaning that said radiation would be a lethal threat to his protagonist should the case crack. Which is of course absurd. Alpha doesn't even penetrate the outer layer of dead skin - alpha emitters are only dangerous if ingested or inhaled, and there's no realistic way to do that with an RTG, they're designed to even withstand unshielded reentry without burning up (and have done so - ex. Apollo 13). He'd be at far more risk of burning his suit - they're designed to operate at temperatures of 1000-1100C on the inner core and can still be very hot on the cooling fins (which, by the way, are often very large - on Curiosity, they're the giant angled section in the right near the guy in this picture. That's just to dissipate the heat used to produce a mere 125 watts of electrical power.)

My explanation of how the Hab is radiation-proof: a superconducting magnetic shield.

Microwave communications are based on photons, aka chargeless particles, aka no Lorentz force, aka no deflection.

Only protects against charged particles though...wouldn't stop gamma rays. How common is random gamma radiation on the surface of Mars?

Nor neutrons. Nor very high energy particles, such as in GCR, according to studies of realistically-implementable systems. But lower energy charged particles comprise the lion's share of the radiation exposure. Also, a lot of the neutrons and gamma that one would be exposed to with conventional shielding are secondaries.

Re:Are and storms that fierce on Mars?

[TheTurtlesMoves]

I have eaten raw potatoes plenty. Never had any poisoning or anything. It is the green that kills, and the potato is not green unless you left it in the sun.

Re:Are and storms that fierce on Mars?

[Rei]

It is apart from solanine. Potato starch is indigestible raw. It passes all the way into the intestines intact, where it then begins to ferment under the influence of anaerobic bacteria. This yields significantly less caloric energy as well as indigestion and bloating.

Anyway, Weir wouldn't have had to worry about potatoes greening (solanine) because he had at least 2-3 orders of magnitude too little light to actually grow potatoes, thinks that the entire part of the plant above the soil is the "fruiting body", and thinks that potato mounding involves completely burying the plant and planting new potatoes directly on top of it. Not to mention the perchlorates, ethylene gas, or the 50 other things that would have actually killed his potatoes if grown as described. (Note to anyone who's ever owned a winter greenhouse or done significant indoor plant growing: expect to repeatedly hit your head against the wall if you read The Martian).

Oh, and try not to think too much about his plan of having humidity condense on the habitat and rain back down as a method for watering the plants (sensitive life-critical electrical systems and condensation: best friends 4everz!). It's bad enough when it happens in your apartment... I remember the day when my light fixture fell to the floor and broke because it had filled up with water and become too heavy to support itself - sure explained the reason why the breaker to that room kept throwing! At least in the movie they seem to have added a grow tent, judging from the trailer (haven't seen the movie yet). Although grow tents bring their own problems... and most clear plastic sheeting is polyethylene, which is a pain to bond.

Re:Are and storms that fierce on Mars?

[SharpFang]

It's not *that* bad - he used electric lighting and the solar farm was much bigger than Hab, so consider sunlight->electricity->light used that way a kind of lensing.
His plan to condense moisture was silly but it wouldn't come to it with the water reclaimer and the dry soil acting as a sponge. Never mind any running electronics would be warmer than the walls exposed to near-vacuum on the other side, meaning a plenty of condensing surface long before the electronics would be endangered.
But yeah, he'd first have to purify the soil. Doable, not very hard, but not done. And his growing methods were... uh, "unorthodox" ;)

Re:Are and storms that fierce on Mars?

[SharpFang]

Thing is they *are* awful so you want to be done with them quickly... so no thorough chewing there usually.

Re: Are and storms that fierce on Mars?

[SharpFang]

yep, my mistake, noticed only after posting.

Re:Are and storms that fierce on Mars?

[Rei]

Clarification on radiation shielding: you generally don't use just a hydrogen rich layering, there may be metallic layers as well (such as the craft's outer skin, tankage, etc). But most of the high energy solar and GCR is charged particles, mainly protons. The lower end of the energy range will almost entirely impact whatever shielding you use, creating a small shower of secondaries. Some high energy particles will impact, some will pass right through. Those that pass through will most likely pass through everything, and those that do impact crew will mostly impart only a tiny fraction of their energy to them. Those that impact the shielding create an ever-growing shower of secondaries; where the secondaries aren't sufficiently blocked poses more of a risk to the crew than had the particle not impacted anything at all on the way in. Primaries at over 10MeV or so are particularly prone to kicking off secondaries, and once you get into hundreds of MeV spallation starts becoming a significant component.

All of this together means that the most important particles to block are the secondaries, in that they're more numerous, less likely to cause negative side effects by blocking them, etc. Heavier secondaries like alphas are easy to block, while it's unrealistic to block a significant fraction of high energy gammas on something as light as a spacecraft. This leaves the neutron secondaries as your prime target for elimination, which can generally be captured if moderated down first, but otherwise pose a risk to the crew. The lighter the element and the higher the cross section, the better the moderator; also, the lighter the element, the more you can carry on a spacecraft. Hydrogen fits all three bills well. Once moderated down, then the capture cross section becomes key. Hydrogen can manage thermal neutron capture over a sufficient distance, but far better is something like boron. In fact, metals can sometimes be counterproductive, especially on the inner side of the shielding. They increase the risk of spallation, bremmstrahlung, and your neutron captures are much more likely to produce short half life isotopes which will then undergo beta- decay.

There's no need for an unusual amount of metal in the shielding (over what would be needed to build the craft itself), and no need to make it a faraday cage. EM radiation and charged particles are very different beasts.

Re:Are and storms that fierce on Mars?

[SharpFang]

don't products of decay of Pu-238 create all other kinds of radiation than Alpha? With it sitting there for a couple years, there would be quite a few...

Re:Are and storms that fierce on Mars?

[Rei]

Yes, it is that bad. And he makes it even worse by boasting about how "incredible" the efficiency of the "super-efficient" panels and then giving it a terrible efficiency, something in the ballpark of 11% if I recall correctly. And then states that the panels are at a fixed tilt (with the "scientist" protagonist not understanding why they'd choose a particular angle... *snicker*) - so they're not sun tracking. Combine this with Mars's low solar constant. Combine this with the dust that he says he has to keep wiping off the panels. Combine this with the not-all-that-impressive panel area to begin with. Combine this with the maybe 20-30% efficiency you might get in producing PAR with a good LED grow light. Combine this with the fact that these are not grow lights, but rather the normal room lighting built into the habitat (white phosphor = loss of energy). Combine this with the fact that anyone who thinks you can grow caloric crops on normal room lighting is a moron, regardless of how much power you have available to you.

I can break it down with exact numbers for you if you want, but I'll just sum it up for you: it's 2-3 orders of magnitude off, and that's assuming that there's no bottleneck of how many lights the habitat was built with, which would actually probably bottleneck it to 3-4 orders of magnitude off. To people who've never grown caloric plants without sunlight, they can be forgiven for not understanding how vastly much energy it takes. Trust me: it takes a *ton*. The sun at Earth imparts about a kilowatt of light per square meter. Per *square meter* - and that's light, meaning to reproduce the sun, you have to use several kilowatts per square meter to account for the losses. Think of how much power an efficient light bulb consumes. Now think of how many of them you need to use to equal a kilowatt of power consumption. And how much of your light you lose to straying.

You have a few things going for you. The sun goes down at night. The sun isn't always high overhead, so you have cosine scaling. So you don't have to produce as much energy as the above implies. But it's still a mind-boggling vast amount of light to need to produce across a very large area. A very good yield of potatoes (which contrary to his claims, you absolutely will not get in his situation even if you had sufficient light - going into why would be a longer post than even this one) - is about 50 tonnes per hectare per year, or 5 kg per square meter per year, or 11000 calories per square meter per year, or about 3-4 days worth of calories for our anything-but-sedentary protagonist, meaning a farm area of about 100 square meters. If one assumes that the reduced solar output caused by sun angles and night to roughly compensate for the energy losses to convert electricity into light and the amount of light that strays, then you need about 1kW constantly per square meter, or 100kW, to match the energy input from the sun. That's the power consumed by 80 average houses in the US. Not like his hab would have 100kW of lights just built into it....

It's easy to forget how intense of an energy source the sun is, and how much energy it takes to keep a human going.

The thing is, had the author not been totally ignorant about plants (despite making his main character a botanist... a botanist that somehow nonetheless seems disgusted by manure ;) ), there are ways one could have reasonably written in a doable scenario. But botany is one of the many, many things that Weir totally bungled in the book.

Re:Are and storms that fierce on Mars?

[Rei]

Nope - it decays to 234U, which has a 246k year half life and is also an alpha emitter. There's some minor spontaneous fission in 238Pu, which can produce basically whatever, but the spontaneous fission half life is 4,77e10 years, which is dwarfed by the alpha half life of 87,77 years. There's also the potential for the occasional alpha side reaction, but the cross sections are extremely low.

Re:Are and storms that fierce on Mars?

[drsmithy]

raw potatoes being merely "awful" while in reality they are quite poisonous.

No they're not, I eat them regularly and have for 30+ years.

Re:Are and storms that fierce on Mars?

[umghhh]

I know this feeling - something is outrageously wrong and you want to tell the world about it. Believe me I have experience with this - this is pointless. It is a nice flick nothing less or more(*). I tend to get this surges of anger too - I sit and write an essay for myself only and list all things that are wrong. Most often though I find that the most annoying parts are not omissions, errors and some such - they are stories where humans hardly play a role or/and which are inconsistent internally. No SF can even hope to describe the reality because of the fiction part. It is not even its role or ambition. The close description of reality does not even get done by most of documentaries so we can excuse a fiction movie as long as it is well made. If the movie about trip to Mars were a bit realistic it would have to include a show of idiocy and corruption on capitol hill as all these billions needed would be only spent if associated with heavy pork lifting and and done on basis of a lie or two about how this is going to cost and what it is going to achieve.
* - sometimes inaccurate and fairy tale like but exactly that is why it is so motivating for some as to show how impossible is possible.

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

OK but he cooked them in the microwave. ?

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

But he cooked the potatoes in his microwave? Why is this such a big point of contention? Did they leave that out of the movie?

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

But the guy cooked them in the microwave. What is the big deal about this? He threw them outside raw, later cooked them and threw them outside again. ?

Re:Are and storms that fierce on Mars?

[pepty]

When the atmospheric pressure is less than 1% that of our own, the total forces are ... pretty underwhelming.

Re:Are and storms that fierce on Mars?

[SharpFang]

Give the habitat spotlights from Rover 1, spotlights from MDV, spotlights from Hab's outside lighting and all the spare bulbs for everything.

The solar panels are hindered by fixed angle and distance from the Sun, but boosted by equatorial latitude and thin atmosphere not dissipating nearly as much light as Earth. Although yeah, 11% is lousy. Let's assume space technology of 2035, and give them a healthy 65%, blaming the 11% on Mark being a botanist.

Remember, individual care of individual plants, optimal temperature and humidity, exploiting the soil to the max, battery power for extended "daylight".

How would the figures look like then?

Re:Are and storms that fierce on Mars?

[SharpFang]

He ate them raw at one point. That's why he decided for the microwaving spree.

Re:Are and storms that fierce on Mars?

[Reziac]

He didn't do too well on the microbiology either. Being freeze-dried doesn't kill an awful lot of bacteria; it just makes 'em encapsulate until conditions improve.

Re:Are and storms that fierce on Mars?

[RockDoctor]

That's an effect, but unless you increase the viscosity of the (saltus, 'a leap') grains don't stay suspended for more than a couple of seconds once the turbulence drops even for a small amount.

If you look at rock pedestals, then their most severe erosion is strongly at the base. Compare the images with a more typical pyramidal hill to get the difference in erosive force between base and top.

Preventing landed craft from over-tipping with such a strongly concentrated low-level force is a job for outriggers. As the images show, the basic problem is hardly rocket science. You can make the engineering as fancy as you want to cut down weight (e.g. - two only outriggers, which can be re-positioned at ~120 degrees to the wind direction ; the weight of the re-positioning equipment being less than a third outrigger?)

I'm perfectly willing to accept the "stranded on Mars" as a MacGuffin. But that doesn't make it any the less of a hazard that would be addressed and managed. Hey, I could even take it fi there were an inconveniently situated Marsquake in the middle of a dust storm. Or a tube cave opening up under the lander because of the stresses of the lander. But it's still a MacGuffin that flies as well as the Maltese Falcon.

Re:Are and storms that fierce on Mars?

[steveha]

He's not "joking around", the rant is like a page and a half long, describing it as vastly more dangerous than Pu-239, with a long line of superlatives for how to describe its incredible "danger".

Either you and I have very different ideas about what Andy Weir wrote, or else your copy of the book is different from mine. Since mine is an ebook, I can search it, and the string "239" has zero hits in my copy of the book.

Here's what my copy says:

...[NASA] never used large RTGs on manned missions until the Ares Program.

Why not? It should be pretty damned obvious why not! They didn't want to put astronauts next to a glowing hot ball of radioactive death!

I'm exaggerating a little. The plutonium is inside a bunch of pellets, each one sealed and insulated to prevent radiation leakage, even if the outer container is breached.

In fairness to your complaint, there is dialog later that goes like this:

"How dangerous is it?" Teddy asked.

"As long as the container's intact, no danger at all. Even if it cracks open, he'll be okay if the pellets inside don't break. But if the pellets break, too, he's a dead man."

Emphasis added by me, not in the original.

From what you have said, it's not nearly that dangerous.

I still say that The Martian is the best "hard" science fiction novel I have read in years, and the "hardest" science fiction novel I have read in years. And I predict that his next novel will have fewer mistakes; this one he wrote and gave away for free, and while he has said that he did go back and rewrite sections when he got feedback that he had screwed something up, I guess nobody told him that the RTG was less dangerous than he thought. On his next novel, he will be able to get stuff fact-checked because he's making new friends everywhere. (In an interview he said people asked him who he knew at NASA and he said nobody... before he wrote it.)

Back to joking around... one of my favorite bits from the book:

Only an idiot would keep [the RTG] near the Hab. So anyway, I brought it back to the Hab.

Either it'll kill me or it won't. A lot of work went into making sure it doesn't break. If I can't trust NASA, who can I trust?

Whatever you think about Andy Weir's safety rants on RTGs, he did have his main character using it just to take a hot bath, and at no point does the main character have any actual trouble with it.

Microwave communications are based on photons, aka chargeless particles, aka no Lorentz force, aka no deflection.

I didn't intend to imply that a magnetic field would stop photons, but rather that the hab canvas might have a layer of something that made the hab into a Faraday cage. Maybe a layer of a low-temperature superconductor or something.

I hadn't actually thought much about the geometry of the superconducting coils that would be needed to make a magnetic shield to deflect charged particles. Now that I think about it, a layer in the Hab's outer skin is unlikely to be the right shape...

I Googled a bit and found this article with diagrams. On the plus side for my theory, if something like that was on the Hab to deflect radiation, I do think it would act as a Faraday cage. On the minus side, the Hab as described in the novel didn't have anything like that.

http://ec.europa.eu/programmes/horizon2020/en/news/shields-manned-space-exploration

By the way, I also had to Google for GCR. You know more about this stuff than I do. GCR == "Galactic Cosmic Rays"

So how common are stray gamma rays, and since you brought them up, stray neutrons on the surface of Mars?

Also, there is an old trope from science fiction about burying an exploration base to provide it with thermal and radiation shielding. If some

Re:Are and storms that fierce on Mars?

[Rei]

Are you really incapable of doing the math?

A LED headlight is something like 30W. Times 2 for two of them. Times three for "super ultra powerful Mars headlights even though an actual Mars mission would be about saving power". Times 4 for "all of the other things you mentioned". That's still only 720W, what you might use to light up a single square meter.

Don't you get it yet? You simply don't "scrounge up" enough light bulbs to grow an entire person's diet worth of food. It's an impossibility - unless you happen to be trapped in a grow light warehouse or something of that nature. Nor do you just "scrounge up" 100kW of electricity. Plants take orders of magnitude more energy to grow from lights than Weir pictures, end of story.

Remember, individual care of individual plants, optimal temperature and humidity, exploiting the soil to the max,

Please don't make me get into why indoor growing in these situations, even with a person who knew what they were doing rather than Weir's countless things that would actually have killed his plants, is a recipe for terrible yields even if the light was ample. Because it'd be practically a book on greenhouse plant raising, and I really don't have time for that.

Re:Are and storms that fierce on Mars?

[SharpFang]

sh1t, did some serious math, then accidentally closed the tab.
First, 1KW light output is if you want Earth's equatorial sunlight, which is far more than plants need - they saturate their input at far less than that. I arrived at 500W (input) of LEDs to produce the needed output for 1m^2, and about 2.5m^2 of solar panels to power them up.

Still, obtaining the needed lamps - yep, 1m^2 per spotlight, 12 per rover (per movie), 10 from other sources, Hab lighting for another 4 or so meters... weaker sources focused on individual plants not to waste energy on lighting up empty soil... that still runs awfully short of the goal, something like 1/3 of what he planned. Not nearly as bad as you predicted, but not nearly as good as Weir thought.

I wonder how much could be saved by adapting growth density. Say, he could light up all the saplings with 2-3 lights, but as plants grow, they need more space. So instead of one massive harvest, to make it so that the grown plants take half the available light, grown in 3/4 half of the remainder, half-grown half of the remainder of that, and so on.

Alternatively, how lethal would space radiation be to potatoes? An extra "tunnel" from transparent plastic, where mature plants would use direct sunlight.

Re:Are and storms that fierce on Mars?

[Anonymous Coward]

Don't forget the shifting sands. Arithmetic shifts are much worse than logical shifts.

Re:Are and storms that fierce on Mars?

[Rei]

You cut short the rant. The full rant is:

Well shit.

I came up with a solution, but remember when I burned rocket fuel in the Hab? This’ll be more dangerous.

No, it would in no way, shape or form be. NASA technicians mess assembling probes and rovers do so without any special radiation precautions, just precautions against burning themselves. NASA technicians do not burn toxic hydrazine inside enclosed spaces that they're breathing that they can't ventilate.

I’m going to use the RTG.

The RTG (Radioisotope Thermoelectric Generator) is a big box of Plutonium. But not the kind used in nuclear bombs. No, no. This Plutonium is way more dangerous!

Completely false. It's far less dangerous.

Plutonium-238 is an incredibly unstable isotope.

It's an incredibly predictable isotope, with really only one meaningful decay branch, and that branch being to another element that decays in the same manner, just slower. The half life is certainly short compared to, say, U238, but there are countless isotopes with shorter half lives than it. Its rate of spontaneous fission are low, as are its fission cross section. This is hyperbole at best, completely false at worst.

It’s so radioactive that it will get red hot all by itself.

And? If he thinks something with an 88 year half life is terrible, he should see how elements with half-lives measured in days or hours are. Note that it only gets "red hot" when stored as a large enough lump inside an insulated container. The heat output on a typical RPG is similar to that of a blow drier or small portable space heater.

As you can imagine, a material that can literally fry an egg with radiation is kind of dangerous.

No, it is not, except for burning you. His freaking out about alpha radiation is totally ungrounded.

The RTG houses the Plutonium, catches the radiation in the form of heat

It "catches" it in the way your outer layer of dead skin, a sheet of tissue paper, or several inches of air would also catch it. Almost anything stops alpha.

, and turns it in to electricity. It’s not a reactor. The radiation can’t be increased or decreased. It’s a purely natural process happening at the atomic level.

As long ago as the 1960’s, NASA’s been using RTGs to power unmanned probes. It has lots of advantages over solar power. It’s not affected by storms; it works day or night; it’s entirely internal, so you don’t need delicate solar cells all over your probe.

No, but you need a giant cooling system and more complicated thermal management. And he seems to be talking about RTG-powered spacecraft, but then talks about "storms" and "day or night" which only applies to rovers, so I'm not sure exactly which he's thinking of.

But they never used large RTGs on manned missions until The Ares Program.

Why not?

Because 238Pu is produced in quantities of only a couple kg per year costing many tens of millions of dollars per kilogram. It is a manufactured product, not a waste product, and consequently incredibly expensive. If one wants more power than can be provided from an RTG, the next step up is a small nuclear reactor, not a larger RTG.

It should be pretty fucking obvious why not! They didn’t want to put astronauts next to a glowing hot ball of radioactive death!

No, you're a moron.

I'm exaggerating a little.

No, you're writing complete nonsense. External alpha radiation is completely harmless.

The Plutonium is inside a bunch of pellets, each one sealed and insulated to prevent radiation leakage even if the oute

Re:Are and storms that fierce on Mars?

[Rei]

First, 1KW light output is if you want Earth's equatorial sunlight, which is far more than plants need - they saturate their input at far less than that.

Yes, one has to incorporate a "capacity factor" to account for angles, night and clouds. Something like 15% would be typical for potato-growing regions. But at the same time, when light is coming from LED lighting, you have to account for stray lighting (light that's not hitting your grow area) and efficiencies at generating PAR, which are 20-30% for proper grow lights, lower for normal room lights (as the phosphor wastes part of the light energy to make it a comfortable white rather than a painful pink). The two issues roughly cancel themselves out. You need in the ballpark of 1kW per square meter of electricity input to match normal potato growing conditions.

I arrived at 500W (input) of LEDs to produce the needed output for 1m^2

For 24-7 lighting, that's 50% of my above, but let's go with it.

, and about 2.5m^2 of solar panels to power them up.

Not even close. Your solar array too has a capacity factor - in the ballpark of 15% if fixed, maybe 35% or so if tracking. Then you have your panel efficiencies. The best large scale commercial panels are 22-23% efficiency. You might get 30%-ish if you used absurdly-crazy-expensive spectrolab cells. Then factor in dust constantly settling on the panels - say 25% loss even with regular cleaning. And Mars's solar constant is only 588W/m^2 *in space*. Earth's is about 1kW/m^2 *on the surface*, 1,4kW in space.

As in the book, 500W for lights per square meter would take 67 square meters of panels per square meter of crops. The best possible situation would take 10,5 square meters of panels per square meter of crops.

Note this is using your 500W figure, which is being kind to you. Double the required panel area to reach mine.

yep, 1m^2 per spotlight, 12 per rover (per movie)

Pure nonsense. 6kW of power consumption for LED lights on a rover? Um, no. Never. Period. That's patently absurd, you'd burn through your power supply in a heartbeat. That's the sort of power you'd use to run a drive motor on a rover on Mars - if you wanted it to drive at speeding-on-the-highway speeds at that. The Lunar Rover motor was only 0,1kW.

How the heck would you even cool a 500W LED spotlight (let alone 1kW, let alone 12 of them) in the near-vacuum atmosphere of Mars? The heat sinks would be massive. LEDs can't run hot, they have to be kept close to room temperature. I have some 600W grow lights. They have a 15kg heat sink and a half a dozen fans on each of them. And you can't practically just cool things with fans on Mars. And they're not like "spotlights", they're about half a meter by half a meter behind the glass panel, and have to be to keep the LEDs far enough apart. It's the reason why LED headlights for cars are a brand new thing, it's very hard to cram many LEDs into a small space without them overheating. A typical modern LED headlight is only about 15W; I was being generous and assuming bright 30W lights.

I wish you were here so I could show you what a 600W LED grow light looks like. It's blinding. The whole world looks pink for a while afterward. And they're massive, heavy things. To put it another way: 600W LED is equivalent to about 5000W incandescent.

I wonder how much could be saved by adapting growth density. Say, he could light up all the saplings with 2-3 lights, but as plants grow, they need more space. So instead of one massive harvest, to make it so that the grown plants take half the available light, grown in 3/4 half of the remainder, half-grown half of the remainder of that, and so on.

The optimal growth method is having 100% of your area lit up at all times, with leaves intercepting 100% of the light. Which can be approximated

Re:Are and storms that fierce on Mars?

[steveha]

Seriously, how can you read this tripe without wanting to hit your head against a wall? How can you call a novel that has this sort of nonsense and does almost every single chemistry equation wrong "hard science fiction"? Does anything that spouts pseudoscientific BS qualify as "hard science fiction" these days?

IMHO you are being too hard on the book. In the book, the things Watney does are plausible solutions to problems that make sense to me.

Andy Weir said he didn't want Watney being "hit by lightning" over and over. The initial chain of events that leads to Watney being stranded is implausible (and Andy Weir is the first to admit that the physics is wrong there, because the atmosphere of Mars is so thin). But once Watney is stranded, the rest of it makes sense to me.

This isn't like a story where someone needs to "restart the sun" by flying a ship made of "Unobtanium" into the sun and lighting off nuclear bombs. If you fix the science mistakes in a story like that, there is no story left; it's just fundamentally wrong.

In an interview, Andy Weir mentioned getting feedback from some chemist, and he said something like "I loved that, because chemistry is what I'm worst at". It sounds like you are so expert at the chemistry stuff that every mistake was a torment for you, and I think I get it... I can picture how annoyed I would be if the book was about software development, and lots of little stuff was constantly wrong.

One of his mistakes: someone actually calculated how much the Hab would heat up from burning up the rocket fuel to make water, and concluded that if Watney burned the fuel as fast as described, the Hab would heat up to 400 degrees C. But that mistake doesn't ruin the book for me, because we can assume that he just didn't burn the fuel as fast, or he arranged some sort of heatsink or something to get rid of the heat. Fundamentally, you can make water by burning hydrazine in the presence of oxygen, so it works for me.

I also liked the way he portrayed NASA. On the one hand, everything NASA does is expensive and takes forever, but on the other hand, his equipment works and he trusts it; and there was one launch that failed, and Weir listed two places where NASA procedures would have prevented the failure if there had been more time. (Someone would have studied the effects of a "shimmy" on protein cubes, and also someone would have found a minor defect in a bolt and replaced it with a perfect one; either of these would have prevented the failure.)

A novel that I hated, that I just couldn't get through, is The Windup Girl. I bought it figuring "anything that wins both the Hugo and the Nebula must be worth reading" but I hated it. I couldn't swallow the science upon which the whole plot rests. It's the future, and the worst predictions of catastrophic anthropogenic global warming came to pass: the sea levels have risen, temperatures are high, lots of people died off. As a result, fossil fuels are no longer used by anyone, and the world is in a horrible depression. So, you might think that nuclear power, solar power, and Internet telecommuting would be a big deal? Nope, cities are lighted with methane gas lamps, and the methane is made from animal feces, and moving things are powered by kinetic energy stored in "kink-springs" and the springs are wound by elephant-sized bioengineered animals. No buildings seem to have solar panels on them, and at one point the protagonist uses a computer powered by a treadle! The Internet barely seems important, which is hard to believe given that the Internet is already hugely important... but in this future catastrophe world it now takes months for a business executive to travel from America to Thailand (he has to travel by wind-powered ship), yet they still send the executive instead of using teleconferencing.

I hated The Windup Girl as much as you seem to have hated The Martian

Re:Are and storms that fierce on Mars?

[SharpFang]

Not even close. Your solar array too has a capacity factor - in the ballpark of 15% if fixed, maybe 35% or so if tracking. Then you have your panel efficiencies. The best large scale commercial panels are 22-23% efficiency. You might get 30%-ish if you used absurdly-crazy-expensive spectrolab cells. Then factor in dust constantly settling on the panels - say 25% loss even with regular cleaning. And Mars's solar constant is only 588W/m^2 *in space*. Earth's is about 1kW/m^2 *on the surface*, 1,4kW in space.

I went with 50% efficiency reduced to 0.7 by morning/evening angles with lack of tracking (Acidia Planitia is equatorial latitudes). That's 2035 space-quality technology. Dust with daily cleaning is non-factor; Opportunity operated for years within some 40-50% loss due to dust, so with daily cleanings it's really non-issue, maybe 2% loss, your 25% would take months of negligence. Due to thin atmosphere, Mars is only something like 560W on surface.

6kW of power consumption for LED lights on a rover?

Only when it switches all of them on. There's a difference between "driving usage" where it may be 500W, and switching the search-lights for emergency when you, say, search for a lost astronaut. In that case 6KW is reasonable.

How the heck would you even cool a 500W LED spotlight (let alone 1kW, let alone 12 of them) in the near-vacuum atmosphere of Mars?

I'd need to come up with estimate of radiation of the surface of Hab, but it's large, white and in very cold environment. There's a plenty of cooling capacity in environment this cold. Yes, air-cooling capacity is poor, but radiational capacity is pretty good considering the radiating surface and the temperature gradient.

I wish you were here so I could show you what a 600W LED grow light looks like. It's blinding. The whole world looks pink for a while afterward. And they're massive, heavy things. To put it another way: 600W LED is equivalent to about 5000W incandescent.

The area lit by them shouldn't be brighter than sunlit area - actually, 25% of sunlight strength would suffice.

Could have, would have, should have. But as it stands, it's 2-3 orders of magnitude off.

We can agree to disagree, I'd say about an order :) But yes, I can accept the botany part of the book was borked. There are more serious errors. Had Weir played Kerbal Space Program for several days, the whole "blowing up the airlock" would be gone - at 2mm/s^2 making a perfect encounter with target moving 12m/s relative to you is some 8 hours.

Still, I have to give it to him: he tried, he did his best, he only made errors because he failed to research even more even though he researched a plenty. We can now hope for a book more accurate, with better science and less errors, now that he's opened the path and showed there's a demand for accurate sci-fi. Even if his own failed to be very accurate.

Re:Are and storms that fierce on Mars?

[steveha]

You know, it occurs to me that you probably quit reading the novel at the worst possible place. You are so qualified to spot mistakes with chemistry and indoor gardening that you were repeatedly outraged and stopped a quarter of the way through. You missed on the later parts where the problems being solved had nothing to do with chemistry and indoor gardening.

I read an article where a couple of orbital dynamics guys said that Any Weir got the orbital dynamics stuff basically right; I've read multiple comments that said that the NASA politics stuff was believable; and in one of my favorite parts, Watney was stuck with a spacesuit whose helmet faceplate's glass had broken and he had to solve the problem of getting back to safety with a rather leaky spacesuit. There are other parts I don't want to mention because they are too spoilery.

You are probably too soured on the book to enjoy it, but if you ever try finishing it, I think you will find that the rest of the book offends you less than the first quarter of it did.

Re:Are and storms that fierce on Mars?

[SharpFang]

One thing more:

But at the same time, when light is coming from LED lighting, you have to account for stray lighting (light that's not hitting your grow area) and efficiencies at generating PAR, which are 20-30% for proper grow lights, lower for normal room lights (as the phosphor wastes part of the light energy to make it a comfortable white rather than a painful pink).

Did you account for PAR fraction of sunlight? LED growth lights have a significantly better PAR coefficient than sunlight - which covers much wider "waste" spectrum than normal room lights. And actually, solar panels have a pretty wide absorption spectrum, so, while we aren't there *quite* yet, it may be in the future that grow-light - solar panel combo will be more efficient than direct sunlight over the same area - and especially with extra batteries storing energy above the saturation level and expending it during weaker sunlight.

As for stray light - With large area growth, stray light isn't that much of a problem. The light that doesn't hit the square below the lamp, hits the neighbor square, and the loss is then covered by stray light from the neighbor lamp. As for the rest, I believe LED efficiencies already account for directionality, light absorbed by the LED casing.

Re:Are and storms that fierce on Mars?

[Agripa]

To borrow a phrase from Niven's "How the Heroes Die":

The sandstorm was at the height of its fury, which made it about as dangerous as an enraged caterpillar.

http://www.e-reading.club/book...

Again VOD release date?

[sims 2]

I'd like to watch it when does it become available on VOD services so I can buy and watch it online?

Still can't find a date anywhere...

Re:Again VOD release date?

[SharpFang]

unlikely to be soon - too early after cinema premiere. BTW, for the story, read the book, it's vastly superior. For the visuals go to 3D theater, they made Mars beautiful. Home-viewing quality of the movie is the worst of both worlds.

Re:Again VOD release date?

[KGIII]

As I posted up-thread, it's not worth seeing at home in my opinion unless you've a *very* good setup. There's little redeeming value other than the eye candy and good acting. It is marginally better than above average and that's only due to seeing it on the big screen. I don't expect it to do well once out of the theater unless they add some compelling content. (I do wonder if it would make an interesting video game, however.)

Re:Again VOD release date?

[tlhIngan]

I'd like to watch it when does it become available on VOD services so I can buy and watch it online?

Still can't find a date anywhere...

You need a date? You can consider in general, a movie hits VOD around 3 months after first premiering. Or probably closer to two months after its off first run status and the cheap theatres get it. This frees up the good prints for other regions.

Movies that have particularly good runs that say in first-run status for a long time will be delayed longer. But 3-6 months is typical.

Right now, we're seeing the early summer movies start to come out, so you can guess it'll be mid-winter 2016 (around say, February) at the earliest, late spring at the latest.

Depends how well the film does. Right now we're in opening weekend.

Stanley Kubrick Went To Mars Before NASA

[Anonymous Coward]

Stanley Kubrick's " 'Dr. Strangelove or: How I Learned to Stop Worrying And Love The Bomb' " while released as a parody and satire of the early 1960's American obsession with 'nuclear death by B-52H and the "Red Scare in Hollywood' is a consummate analysis of Post-STS NASA and NASA's fixation on a thing called 'MARS'.

Ha ha

Please Ignore This Post

[Anonymous Coward]

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Re:Please Ignore This Post

[Anonymous Coward]

821f 9e78 61fe a6bb
1c13 9bc6 e0b4 6b5b
83e8 3f48 4908 9556
d112 fc7c ee62 8cda
034b 19b8 009f 124b
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f8b3 9626 1d1b bce7

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Re:Please Ignore This Post

[Rei]

Aaargh... why do I always fall for the Rick Rolls? :P Well played...

Re:Please Ignore This Post

[Anonymous Coward]

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The Martian

[jeanheikkila]

Ever since 1977, when a little movie called Star Wars caught the public’s attention, the space opera has been the go-to subgenre for mainstream movie sci-fi. There’s room for other takes, like Duncan Jones’ 2009 cult hit Moon or this year’s excellent Ex Machina, but those are usually tiny films that play at the edges. When it comes to big studios and big budgets, it’s all about action and sweeping melodrama (with a little futuristic dystopia thrown in from time to time) — with little to no time for philosophical ponderings or scientific details.

Boy are you humorless. It's Science FICTION.

[Anonymous Coward]

Boy are you humorless. It's Science FICTION. The whole "scientific accuracy" part is just PR, and to the extent it interests people in science it is good - because everyone (even scientists) has massive misunderstandings of science and reality and it is good to get people engaged in discussions.

Surprised you didn't include one of your biased rants against Assange.

Real World?

[RockDoctor]

how a real world interplanetary spacecraft would pull off a rescue maneuver

Well, for starters, they wouldn't leave someone behind who wasn't dead and buried. "Dead" in the sense of "injuries incompatible with life" and/ or "failure to revive" and/ or "decomposing". This has been established by long history of mountain, cave and other remote area search and rescue incidents. If you want a ball-shrivelling account of how hard it can be to tell, read Joe Simpson's "Touching the Void" (the film wasn't too bad either; but remember that despite having been filmed by Hollywood, the events were reality. Including the crawling through the shit garden).

I suppose I'd better go and RTFA, but having just come back from a 2-million dollar/day operational planning meeting, the plan of "don't get into that situation" plays a really important role here.

Re:Real World?

[dpidcoe]

This has been established by long history of mountain, cave and other remote area search and rescue incidents.

Wait what? iirc the path up to the summit of Everest is littered with bodies of climbers who couldn't make it. Including one who was reportedly injured but alive for several hours. Other climbers talked to him as they passed, but there wasn't anything they could do as attempts to help would just result in both of them dead.

Re:Real World?

[david_thornley]

In the book (haven't seen the movie yet), the storm slammed a piece of metal into Watney's suit and into his body. He was knocked unconscious, so he was unresponsive, and IIRC they couldn't see his body immediately. The instruments in his suit were damaged, and so his telemetry was gone. It was a crisis situation. People will leave an unburied colleague behind in those circumstances, if they think him or her dead.

Re:Real World?

[RockDoctor]

Yes, they knew where he was and couldn't (or wouldn't) do anything to help him. But they knew where he was. The big difficulty, particularly for people who are intending to help, is if you can't find someone who you think is missing, or if you think someone is missing, but don't know they are missing. Or in the cave rescue scenario, you know someone is in a cave somewhere within walking distance of here, but you have to thoroughly search every one (including the unexplored or un-published ones), when there is no way of knowing if you're within 2 feet of the missing person or party unless you're actually within the same cave system as them.

Everest isn't a good example of normal mountaineering because there are a lot of people who take their egos and business plans there, leading to some extremely distorted and aberrant behaviour. That it also makes headlines is unfortunate. It'd probably do a lot of good if the Nepalese government shut it down for a decade or two, or required people to have climbed all the other 8 thousanders before being allowed on Everest. That should weed out the money bags and incompetents.

Re:Real World?

[RockDoctor]

Wait - hang on. The wind was sufficiently powerful to pick up an item of mean density 3 or 4 tonnes/ cubic metre. and "slam it into" something of mean density about 1+a-bit tonnes per cubic metre which wasn't moving. I don't know about you, but when I last got picked up by the wind, my ice axes (metal and GFRP ; they sink, I float) stayed laying on the ground because they were denser than me. (My rope also held, which is why I was using a rope.)

Oh, sorry, I'm forgetting that the "left behind on Mars" is a MacGuffin. Given that it's over a decade since we put the first (semi-)permanent mapping satellites into Martian orbit, such a storm sneaking up on a landed mission simply is not credible.

I only had four of my six impossible things before breakfast today. But I feel full, and don't think I can swallow that one.

Re:Real World?

[dpidcoe]

Everest isn't a good example of normal mountaineering

I suspect that Mars isn't a good example of standard operating procedure for mounting a rescue either.

Re:Real World?

[david_thornley]

It's a way of leaving Watney behind that seems maybe plausible if you don't think about it. That's the best I can say about it. It does explain why the rest of the expedition might leave without verifying his death.

In Earth's atmosphere, it is possible for wind to drive solid objects through others, but it typically takes a tornado. I have no idea what sort of wind would be required for the Martian air to do that.

Re:Real World?

[RockDoctor]

It's a way of leaving Watney behind that seems maybe plausible if you don't think about it. That's the best I can say about it.

That's not a lot to say, really. I prefer my sf to engage my braincell a bit more than that. Well, I'll probably see it at some point, but I can't say that I'm motivated to actually go out of my way (e.g., to a city with a cinema, or to log onto the wife's DVD library website to book it) for it. I'll see if the copy of the book turns up on the recreation room's library. Frequently the book is considerably better thought out than the screen play. Different audiences.

In Earth's atmosphere, it is possible for wind to drive solid objects through others, but it typically takes a tornado.

A rather different situation. In one case, one object is stationary and the other is acquiring kinetic energy by being blown around in the wind for an indeterminate period of time. (Actually, there was another SF film a few years ago where the MacGuffin was a device for measuring some aspects of that movement.) In the other case, both objects start at zero velocity (with respect to the ground and each other) in the significantly slower wind at ground level.

I have no idea what sort of wind would be required for the Martian air to do that.

I don't have numbers to hand, but work has been done on this looking at dust devils (mini-tornados) on Mars, imaged by the very mapping satellites I mentioned earlier. There are also weather stations on all of the landers, of varying degrees of complexity. We may not have as good an understanding on Mars as we do on Earth, but our scientists and their robots are finding out this sort of thing.

I swap tweets from time with a guy whose signature line was "There is a robot on Mars. I give it instructions, and it does what I tell it to do." I like keeping up to speed on interplanetary exploration activity.

Re:Real World?

[david_thornley]

Unfortunately, since I haven't seen the movie, I was talking about the book. It's probably more accurate, but it is disappointing when a hard SF book starts off totally fudging something. I'll probably see the movie Sunday.

I swap tweets from time with a guy whose signature line was "There is a robot on Mars. I give it instructions, and it does what I tell it to do."

Cool!

Re:Real World?

[RockDoctor]

Niven, of Ringworld, once wrote that he likes to keep his SF to no more than 6 impossible things per story, because much more than that allows you to get the protagonists out of any scrape. The "with one mighty leap, he was free" syndrome. So, faster-than-light travel at 3 LY/day (subjective), plus ageing-retarding "boosterspice" makes for a more interesting "universe" than infinite velocity and infinte lifetimes. An unbreachable protective shield ruins wars, unless it needs someone on the outside to turn the field off.

The Mars rover guy - now writes code for Google - tweets as @Marsroverdriver.

Plastic foil as strong as pressure door?

[Zefirowy]

What about that? For me, that was the weakiest idea in whole movie. Almost vacuum outside - 0.6 kPa (0.6% of Earth's atmosphere pressure), lowest possible inside (if pure oxygen): 56 kPa. Hole diameter about 2 m, which gives 176 kN (or more easy to imagine 16 tons of Monty Python's sudden weight)...

It's a movie!

[barrygrommit]

Wow...I do hope that slashdotters realize that this was a MOVIE...FICTION. Geez...it's not Star Wars, which really was scientifically accurate, down to the ability to vulcan mind meld. oh...wait. Wrong movie. oops...Beam me Up!

Re:It's a movie!

[Anonymous Coward]

Well, if it's "just fiction," why didn't they fictionalize everything about Mars, like they did in John Carter?

"Sure, I can jump a mile in 38% earth gravity, it's just a MOVIE!"