It was addressed to Vogel in the movie too, but there was no bad German to alert him. He just couldn’t open the file and needed Johanssen’s help.
Speaking of the book, it has a great opening sentence: “I’m pretty much fucked.”
Did they mention the Hohmann orbit for the Hermes? I only recall them mentioning it for the supply mission.
The Ares-III had a OMS system, because the pilot used it to prevent the MAV from tipping over.
In the book, it says “The orbital maneuvering system has three redundant thrusters. We’ll get rid of those.” I’m not sure if that meant getting rid of backup thrusters, or all thrusters.
The MAV was only designed to get to low Mars orbit, not match speeds with a flyby. They thought they reduced the weight enough to do this, but when the Hab canvas covering the front of the MAV blew away, the increased air resistance caused the shortfall in speed. At least that seems to be the excuse in the book.
This makes me wonder why anyone thought the Purnell Maneuver was a good idea, if there was so little margin in the MAV performance. They must have known from the beginning how much mass they needed to remove from the MAV to make it work, and what that entailed.
OK, point taken. I still think most of the cost is opportunity cost (other missions being delayed or canceled to make the rescue possible) rather than dollar amounts, but that is still a cost.
Those panels on the side of the Hermes that are facing every which way I think are supposed to be nuclear heat radiators, Stranger. NASA didn’t figure out that Watney was still alive for weeks after the Hermes left, because they were afraid of the bad PR of airing images of his body. (per the book)
I think you’ve got a major point regarding the MAV reliability. As for why it doesn’t seem to have any attitude thrusters - I guess they could have removed the hypergolic fuel tanks, or vented them, in order to shed mass? 5.6 kilometers per second in a vehicle designed 3 or so is an enormous change, isn’t it? I guess they left a limited amount of hypergolic fuel onboard for control during ascent, and there wasn’t enough remaining after dealing with the unbalanced drag from that tarp coming loose. Per your max Q numbers, that is apparently totally plausible. Watney wasn’t injured by the wind stream at max Q, he was injured by a peak acceleration of 12 G - they ran that MAV to the absolute limits at 120% throttle or something the entire ascent to eke out all the performance possible.
Stranger, if during the Apollo days they wanted to use the LM as a lifeboat, why didn’t they make the lithium hydroxide canisters compatible with each other from the beginning? Actually, that brings up the question of why didn’t they share life support components in general between the spacecraft to simplify design.
In the book, it’s not that the rover used the same comm software as pathfinder. Basically, it was a bootstrap hack. They had very little bandwidth to talk to watney - they had to send commands to move the pathfinder camera servo while Watney was standing there with a clipboard, writing down the output in hex.
So what they did was, the hardcore hex hack of the rover essentially put it’s radio into a mode where it listens on a frequency the pathfinder can broadcast on (the rover radio was probably software defined and able to do a huge frequency range) and it would accept a repeating binary message coming from the pathfinder lander and load that message, after correcting errors, as executable code and run it.
So the JPL guys created a whole software application that would run on the rover, and they just needed Watney to hack the rover so the rover would start loading the binary stream of that application. They found a way to do it that involved making very small changes to the rover software. Frankly, they may have used hacking techniques like deliberately buffer overflowing the rover OS and so on - that hex change that Watney made might have just been something like “listen on this frequency. When frame read, move instruction pointer to beginning of frame. Disable buffer overflow protection.”
It was something simple like that, and then the message being broadcast by pathfinder would have done the rest, allowing NASA to ultimately upload a multi-megabyte patch if they wanted to.
Now that I think of it, the German tag on the e-mail in the book was not bad German. It just said “Our Children” in German when actually he and his wife always called them by a pet name. He thought it odd that she didn’t use it.
It was addressed to Vogel in the film too, but he wasn’t German, and the file was labeled “Our Children” instead of 'unserer kinder".
Looking around, I found this animation of the Hermes’s course trajectories - the planned mission, the immediate return to earth after the abort, and the ‘Rich Purnell’ trajectory:
This is based on the book, where the abort was on sol 6, rather than on the movie where it happens a few sols later, but that shouldn’t change much.
The Rich Purnell trajectory is something. The flyby with the Earth puts the ship into an elliptical orbit that takes it scarily close to the sun, coming within the orbit of Venus unless I’m mistaken, and would take it well outside the orbit of Mars too. After passing Mars and picking up Mark they have to aim the engines ahead of them and slow down hard to drop back and return to Earth. It’s no wonder that the director at NASA didn’t like the plan, there are multiple ways this could not just fail but cost them the only interplanetary ship they have.
Also worth noting that the MAV doesn’t just have to make orbit around mars, it has to match velocity with a ship that’s going far too fast to orbit. So if Mark doesn’t get picked up, he’s not falling back to mars, he’s going into an elliptical orbit around the Sun.
Thanks, that is very good!
Yes, the LM had a single descent and single ascent engine. Had either of them failed in operation the LM would have crashed or been disabled with the astronauts stranded. This was considered the single largest reliability issue with the Apollo/Saturn lunar system and received corresponding scrutiny. The engine design that TRW came up with for the Descent Propulsion System used a highly throttleable engine with a pintle injector that has lineage to the TRW TR-106 Low Cost Pintle Engine which itself served as a basis for the original SpaceX Merlin engines, although the Merlin design has evolved significantly since (and uses RP-1 instead of LH[SUB]2[/Sub] as the fuel). The engine for the Ascent Propulsion System was even more simple, and yet Bell Aerospace (the contractor for the engine) had substantial problems in the development. The engine itself had to be rebuilt after every testing because of the low margins and materials that did not resist corrosiveness of the hypergolic propellants, and therefore could not be tested prior to use.
The lithium hydroxide canisters for the CSM and LM were not the same because there was no requirement early in the development and the notion of using the LM as a lifeboat and for alternate purposes was proposed by Grumman later in development. The difference in form factor was also governed by the relative space in the CSM and the LM. The LM was well behind schedule and had numerous problems in development such that it was on the critical path to flight during the entire development program and so making a radical change (which it would have been) would have badly compromised schedule for a contingency nobody considered particularly likely at the time. Although much was made of building the adaptor in the Ron Howard film, it really wasn’t that big of a deal compared with some of the other challenges such as the multiple correction burns and loss of environment thermal control.
It should be noted that the Apollo program was very specifically a high risk program that, according to some estimates, had a 50% chance of failure for the first landing attempt despite all of the effort put into testing. It was just way more marginal than anything designed to operate under current crewed mission reliability requirements and the durations necessary for an interplanetary mission. That duration, and the number of unavoidably high risk operations for a crewed Mars mission increase the reliability burden dramatically such that going to Mars with a comparable risk level requires enormously more (by orders of magnitude) component level reliability and/or fully redundant operations, hence the large cost estimates for such a mission.
Having not read the book or looked at supplementary information I wasn’t aware of this but it makes sense. (I was so jazzed at just hearing the mention of using a Hohmann transfer orbit at all that I didn’t really track that it was just for the resupply mission.) Yes, doing those trajectory simulations at a first order level is pretty easy, either using publicly available codes like POST or Copernicus, or the multitude of internal codes that JPL and the other NASA centers have developed for various purposes. I have a homebrew code written in Matlab and C that is only a few hundred lines to calculate ephemerides and map discrete impulse trajectories. What was a little silly is that one guy was apparently calculating the trajectory, as well as his sitting in a server farm with his laptop connected and waiting for the “Calculations Correct!” message to pop up. (I sure wish my analysis codes would just tell me that the solution is correct instead of relying on me to interpret the data and draw my own conclusions.) The briefing of a junior trajectory analyst to the director of NASA, sans any kind of briefing charts or review panel, was also a little absurd. But I realize that these were done for the purpose of dramatic tension and/or comedic effect. Nobody, and I mean nobody, wants to watch the five tiers of briefings and peer reviews it would take to get to that level even in an emergency.
I didn’t really understand what they were trying to accomplish with the covering. It didn’t have enough structural integrity to protect against any significant impact, and of course it is going to come free during flight; we generally hate textile elements like rocket cozies or covers with a passion just because they are so unpredictable and tend to snag on things, like the STARS vehicle that failed flying out of Kodiak last year. However, it still doesn’t explain why the MAV capsule doesn’t have at least an ACS or RCS system on-board to correct for rotations and allow fine maneuvering at docking. It’s a minor point, but I can’t imagine designing a spacecraft of this type, intended to separate from the propulsion booster and its ACS system, that didn’t have some kind of on-board ACS/RCS.
Not to mention losing the rest of the crew. It’s really a pretty bad plan, but as pointed out, the resupply plan also had a large number of uncertainties and untested operations. In reality, I would expect that NASA would already have a contingency resupply plan sufficient to support the entire crew in the case of MAV failure or other problems (high ionized particle flux predicted during the transit profile or other problems that might strand astronauts on the surface for a longer mission duration).
If Watney missed the intercept he’ll end up in solar orbit instead of around Mars, but he’d be dead either way, as he has no way to return to the surface (and apparently no supplies or habitat to survive in) so there really wasn’t a fallback regardless. That’s just the nature of orbital ballistics, and the same thing applies to planetary swing-by maneuvers and other critical energy operations; you will only get one shot to get it right, else you are sailing off into the black.
Mind you, these are all fairly minor nitpicks on the film. It got the technical details far more right than almost any other movie I can think of, and even the botany behind growing potatoes was plausible. I especially liked his speech in the end which didn’t minimize the risks inherent in crewed spaceflight, and the necessity of “working the problem” over giving up or engaging in heroics, notwithstanding the ‘Hail Mary’ retrothrust maneuver by venting the bow airlock.
Stranger
Just came back. Pretty awesome but not anything at the top of the all-time SF list at least.
I thought the rover journey/ending was pretty rushed (the pacing all of a sudden got sped up towards the end), and they didn’t mention the canyon that he had to navigate. I hope stuff like that gets put in an extended edition…
It had imperfections, yet, but can you actually name 10 sci-fi movies that were better? I guess I’m giving it a lot of weight because it was “fictional science” - some technical errors but more or less it could physically have happened that way. The instigating event would have had to be something else, but it is possible for the crew to be forced to leave early. Even classics like 2001 both depend on alien space-magic for the premise, and as it turns out, the fusion spacecraft in 2001 is at the extreme limits of what is even vaguely plausible at all.
I have a thought.
The night before their scheduled MAV liftoff to rendezvous with Hermes, the Ares III crew gather in the Hab. After a fight with Martinez, Mark Watney is sent to the third floor of the Hab, where he wishes that the crew would disappear. During the night, a power outage resets the alarm clocks and causes the crew to oversleep. In the confusion and rush to reach the MAV on time, Mark is left behind and the crew is unaware until they are already airborne.
Yes, Vogel was German in the film too. The e-mail was labeled “Our Children” in English in the movie, but I figured that was because non-German-speaking moviegoers might not know what “Unsere Kinder” meant. Or maybe it being in English was a clue to Vogel that something was up but the movie did not go into it.
In the book, the email title is “Unsere Kinder”, which Vogel knew wasn’t from his wife, because they always called their kids “Unsere Affen”, “Our Monkeys”.
Yes, but the movie decided not to go into it the esoterica of the e-mail line.
Vogel was definitely German in the movie. The book spelled it out, while in the movie his space suit carried an EU flag patch and he spoke with a German accent.
I just saw the movie today (have not read the book), and while personally I didn’t think his accent sounded very German it did seem clear that the character was meant to be German. I’m pretty sure he was jokingly referred to as a Kraut at least once – I think Martinez made some crack about his “weird Kraut porn” or something along those lines.
That’s right, Martinez did. I remember that now. Vogel’s accent was not very pronounced, but it was there. I may have picked up on it more because I already knew he was German.
Their reaction doesn’t have to be absurd or cartoonish for the additional stress to potentially cause a problem. Trained astronauts aren’t robots, and human beings have noticeably reduced capacity when dealing with grief and stress and guilt.
Probably true. But if it happens on Earth, and not while they’re piloting a $billion spaceship, well. I can see NASA choosing to let them suffer some extra anguish to improve the chances of the rest of the mission even slightly.
You’re misremembering. Until he gets Pathfinder, NASA thinks he’s going to starve before they can even get supplies to him. And no one knows about a way to get Hermes back until Rich Purnell figures it out, after the first failed probe launch, and after NASA has already told the crew about Watney (which they did because there was a viable plan to rescue him).
His film career began with everyone around him trying to convince him to LEAVE home.:o
Guess they have some upgrades to look forward to in the next 20-some years.
Very cool - thanks! Wish they’d shown something like that in the movie.
Not an EU flag, but a German one.
