“Venk, have you got a minute?”
Venkat looked up from his notepad, where he’d been doodling numbers, graphs, and rough diagrams of the MAV. “Of course, Annie,” he said. “What’s wrong?”
Annie stepped into his office, shutting the door behind her. “What makes you think anything’s wrong?”
“Well, for starters you’ve just said two almost grammatically correct sentences in a row in private without any profanity,” Venkat said. “Also, you usually greet me with a demand of some kind or a complaint about how tough your job is. That plus your tone of voice tells me you have tremendously bad news for me, or else you want a special favor.”
“Fucking Sherlock Holmes,” Annie muttered. “Yeah, you’re right. I want a special favor. There’s a reporter who’s done me favors in the past, and she wants a one-on-one interview with the alien captain, Cherry Berry. I want to know when we can get her a day on the Pathfinder chat.”
Venkat dropped his pen. “Annie, do you have any idea what you’re asking?” he said. “Lightspeed lag is well over twenty minutes now. And that’s not counting typing time on both ends. Total bandwidth is well under a kilobit per second. We’d have to push everything aside for that, and your reporter might get ten, eleven questions and answers, tops. Can’t she settle for email and follow-ups?”
“She says she wants a live interview,” Annie grumbled. “I know the problems, Venk, I see the time-stamps on the chat. But this is Berenice MacReady at the Times of London. She’s practically our biggest cheerleader in Europe. Do I need to remind you about all the ESA funding that’s going into the rescue effort? Because Bernie reminded me, Venk. Gave me chapter and fucking verse on it. And she’s done her best to sell our spin on every aspect of this thing, so we owe her big.”
Venkat sighed, leaning back in his chair and considering the logistics. “If we do this, every other news source is going to demand interviews, too,” he said. “Can you deal with that?”
“I’ve been dealing with it for weeks,” Annie said firmly.
“NASA can’t be seen to play favorites,” Venkat continued. “That means the only way we don’t get a black eye from this is if we arrange things so that Cherry requests the interview. You’ll have to make that happen, in secret.”
“Doable.”
“Your friend will have to be on-site either here or at JPL,” Venkat said. “Considering the chaos in Pasadena right now, here would be better. And she’ll have to be here for days until we hit a day with no urgent business. Is she good with that?”
“She’s already part of the press pool here,” Annie said. “She lives in a microsuite hotel down in Texas City. It won’t be a problem.”
“And impress upon her,” Venkat added, “that her time is extremely limited. The first two hours of a day is ours for daily business. She gets nine hours after that, if we don’t need to break in for some kind of emergency. So she’d better get what she needs as quickly as possible, because she won’t get a second chance.”
“I’ll tell her.”
Venkat sighed. “Then set it up,” he said. “And you and she both owe me big time, Annie.”
“Put it on the tab,” Annie replied, utterly without shame or gratitude. She glanced down at the desk and saw Venkat’s scribbles. “What’s this all about?” she asked.
“Drinks-napkin guesstimates,” Venkat said. “Trying to get some idea of how much good it would do to bolt the pony rocket engines onto the landing stage of a MAV.”
“Isn’t that JPL’s job?”
“Yes, but it gnaws at me,” Venkat said. “And it’ll be a couple months before JPL gets serious about it. Their hands are full with Sleipnir right now. So I’m working the numbers for my own satisfaction.”
“How do they work out?” Annie asked. “It seems to me it’d make things worse instead of better. For years you’ve had me explain to reporters how important it was to keep the MDV and MAV as lightweight as possible to save fuel.’
“How much do you know about thrust-weight ratios?”
“If thrust to weight is about one, you hover. If it’s more than one, you fly. If it’s less than one, you either stay on the pad or you crash.” Annie shrugged. “After that it’s egghead territory, and I get lost.”
“Okay.” Venkat pulled out a fresh sheet of paper and began drawing. “The MAV landing stage has a thrust-weight ratio-“ he labeled this TWR- “-of 1.2 in Martian gravity. That’s very little, but it’s all it needs to slow the MAV from about one hundred meters per second to a safe soft landing in under three minutes.”
“Why not more power? Bigger engines? More fuel?”
“The more weight we put on the craft to start with, the more fuel we need to launch it from Earth, and the harder it is to soft-land on Mars,” Venkat said. “That trade-off, by the way, is why the MDV landing is the single greatest point of danger for Ares astronauts. Once an MDV enters atmosphere, there’s no abort scenario. It’s land or die. Building it to include an abort mode back to orbit would make it as big as the MAV.
“But I’m getting away from the MAV. The MAV runs on hydrazine using a catalytic grill to make it hypergolic. The thrusters on the MDV use the same fuel. Between the residue in the Ares IV MAV and the Ares III MDV, we might get one minute of flight out of that stage. In theory that’s bonus acceleration, an early boost to orbit.”
“You say in theory,” Annie replied. “Obviously not in real life. Why?”
“In Mars gravity, a TWR of 1.2 means only 0.76 meters per second of acceleration every second. That means, after one minute, the whole ship would only be going about forty-five meters per second. Coming down that's OK because the MAV uses parachutes and aerobraking to go from orbital velocity down to below 100 meters per second, and the rockets can take it from there.
“But Mark and friends need to get to something like six kilometers per second, and while forty-five meters per second is nice in theory, it's suicidal in practice, given the time required for staging. At the end of one minute, the rocket would just barely be even with the rim of Schiaparelli Crater. In less than ten seconds it would begin falling, and twenty second after that it would hit the ground again. The MAV pilot would have to manually light the first ascent stage engines and release the launch clamps connecting it to the landing stage without a bobble or a hitch, or else they die. Or, if they do it slowly but well, they end up using more fuel in the first stage than if they’d just launched normally.
“So, long story short, re-using the descent stage alone doesn’t buy us enough speed or altitude to be worth the danger to the crew. But if we add the alien ship’s main engines to the mix, the math changes.”
“How so?” Annie asked. “More weight, right?”
“Yes, more weight,” Venkat agreed, “but a hell of a lot more thrust. Our ballpark estimate is that those three engines at full throttle could hover forty-five tons of weight on Mars. That means they produce forty-five Martian tons of thrust, for a TWR of one. But if they’re just lifting themselves, that TWR is a lot better.”
Annie shook her head. “You’ve lost me.”
Venkat tapped his chin with his pen. “Okay, forget the MAV and the ponies for the moment,” he said. “Let me tell you of the thrilling adventures of Captain Buck Watney in his faithful potato-powered spaceship.”
Annie smirked. “Thunderspuds are go?”
Venkat smirked back. “Something like that. Thunderspud 1 weighs fifty-two tons at launch, and its first stage produces sixty-two and a half tons of thrust, for a TWR of about 1.2. But he’s in a hurry, so he needs some boosters to get to space quicker.”
Annie nodded. “Okay, I see that. Kind of like the space shuttle or Falcon Heavy?”
“Exactly. But let’s say a certain ex-president sells Buck Watney a couple of boosters with his name on them.” Venkat drew a couple of missiles next to a more conventional sci-fi rocket shape. “Let's say each of these weighs five tons and produces four tons of thrust, for a TWR of four to five- less than one. What that means is that, launched alone, these so-called rockets wouldn't even leave the pad until half of more of their fuel was expended.
“Strapping two of those onto Thunderspud 1 produces a craft that weighs sixty-two tons and produces seventy point five tons of thrust at liftoff, for a TWR of 1.137.”
“Which is less than 1.2,” Annie nodded. “Congratulations, Watney's just wasted the Space Orphans and Widows Fund in order to fluff an ex-president’s ego.”
“Right. And Buck Watney is upstanding, honest, and not an idiot,” Venkat said, “so he doesn’t do that. Instead he chooses the Rainbow Mustang Sparkly Necklace System. The system weighs seven and a half tons, but produces a whopping forty tons of thrust. Now that’s a different story! Wrap one of these around Thunderspud 1 and you get a ship that weighs 59.5 tons and produces one hundred two and a half tons of thrust at liftoff, for a TWR ratio of about…” Venkat pulled a calculator over and did the math. “…1.72.”
“Which is lots more than 1.2, right?” Annie asked. “Buck Watney must really be moving.”
“Not that much,” Venkat admitted. “To give you an idea, the Saturn V and the Space Shuttle both launched at about 1.5 TWR. But fuel consumption lightens the load, so both vehicles had a peak TWR of about 3. We launch unmanned vessels at a peak TWR of 15 or even higher because, unlike people, probes don't get broken ribs and internal bleeding due to high G loads.
“But getting back to reality,” Venkat said, “those numbers I gave you didn’t come from nowhere. The MAV with landing stage is fifty-two tons, including fuel. On Mars it has a TWR of 1.2. And the pony rockets- the Rainbow Mustang Sparkly Necklace System- weighs four and a half tons, plus about three more tons for the batteries needed to power them all for about a minute. On Mars they can lift about forty-five tons. And one minute of acceleration at 1.72 TWR on Mars comes up to about three meters per second of acceleration. At the end of that minute, the MAV would be going roughly two hundred meters per second at an altitude of almost six kilometers- a safe speed and height to cut loose the landing stage, light the first ascent stage, and really begin moving.”
“Okay, I’m up with you now,” Annie said. “But why not add more batteries or more fuel?”
“For one thing, the ponies only have materials on hand for about a hundred batteries maximum,” Venkat said. “Beyond that they’d have to make the frames, controls and connections from scratch. For another, we’re not one hundred percent sure they can make more hydrazine, and the landing stage engines aren’t compatible with any other fuel they might be able to mix from materials on-site.
“But the biggest reason is weight,” Venkat said. “We can’t extend the pony engines to run for the full burn time of the first ascent stage. That’s just not an option. And we don’t have a safe, non-destructive way of detaching those engines when they burn out. There’s a chance the parts would collide with the engines after release and wreck the ship. So if we put them anyplace other than the descent stage, they’d be dead weight for at least one minute of the ascent. And we can’t afford any dead weight at all on this launch.
“So, if we can find a way of doing it safely, we’re going to attach the pony engines to the landing stage, burn it for a minute, and drop it all and let it crash back to Mars.” Venkat sighed. “It’s a horrible waste, but unless we can figure out a way to replace some of the upper stage engines with the pony engines, it’s the most efficient way to use them.”
“Huh,” Annie said.
“Beyond this, Bruce will tackle the other end of the equation,” Venkat continued. “That means ditching everything Mark and friends can live without to make the ship lighter. Any weight we can strip from the MAV will increase its TWR and make all the engines more efficient. That’s where our real hope for rescuing them lies- that and the Sparkle Drive.” He shook his head and added, “Gods, I hope we don’t need to use it.”
“Huh,” Annie repeated.
“Did I lose you again, Annie?”
“No, no,” Annie said, smirking. “I’m just wondering how Watney will react when I tell him we’re changing the MAV’s name to Thunderspud 1.”
“What?” Venkat glared at Annie. “No. No no, no no no. You are not going to-“
“See you later, Venk,” Annie said, “I have a press conference in seven minutes.”
“Don’t you dare tell him, Annie, I mean it!” Venkat snapped. “Do you hear me? You get back here!”
On Mars, inside the crystal cave extending under Site Epsilon, the temperature warmed.
The alfalfa plants, extending only a foot or so above the surface, delved several meters below, deep below the cultured topsoil painstakingly developed by the castaways and into almost virgin Martian soil, pushing and prying against the gradually melting permafrost. The roots brought with them bacteria from the upper soil levels, mostly beneficial, but a few less so.
The newly reinforced, airtight silicon dioxide and regolith-concrete walls of the cave acted as a superior heat insulator, allowing the heat produced by the solar lighting system, the water heating pipes, and the space heater to remain in the cave. The heat warmed the air, warmed the plants, and gradually warmed the soil, to depths none of the castaways were aware existed.
The castaways thought the lava tube was symmetrical, sloping down as it approached its source at the center of the ancient dead volcano. They were wrong. The dust and soil that had blown in from the surface sloped down, but the rock beneath it sloped up as you reached the rear of the cave. Put another way, the dirt near the entrance was deeper, far deeper, than the vast open area above.
And in its depths, below the plain water ice permafrost, there were more ancient deposits, of water and of other things that welled up from the depths rather than down from the shallow layers of Martian sand and rock.
Trapped in those deposits, where they had remained for uncounted millions of years, were pockets of methane hydrate, ice that contained large amounts of methane in its crystalline lattice.
The alfalfa roots reached down, bringing warmth and bacteria to the depths.
The first of the methane pockets began to thaw.
Tiny trickles of methane gas began, very slowly, to permeate up through the root system, displacing the oxygen in the soil. Beneficial bacteria began to die off.
Less beneficial bacteria tasted the methane and found it good.
They were fruitful, and multiplied.
I didn't realize my day needed some Annie in it, but there you go.
Also, fck methane.
*Story cuts to raw narration.*
"Fuck."
*Less beneficial bacteria found it tasty...*
"Double Fuck."
I know this scenario. We're about to run into the problem that happened with the biodome experiments.
WEll... fuck.
Well shit. Goodbye cave farm. Kinda excited tbh. We haven't had a disaster since the Hab blew out.
Uh oh. Clock is ticking if they're gonna salvage the cave.
Methane, eh? The cave's about to go boom.
8873340
not really if they can fight this off they can't save the hey but the trees will be ok for the most part
This planet has issues. It's a shame the farm is unlikely to continue to grow after mark and the crew are gone, I was hoping the farm would be a self contained ecosystem that stood as testament to resiliancy and hope.
Also thunderspud 1 is a great name.
the hay is long gone now, but the potatoes and trees will be ok for the most part, all they have to do is fix it up is to well found that hot water cave remove it and fix it all up may took a few but will be worth it in the end
Ohh, i wonder if Dragonfly, Mark or Cherry can sense this.
But even if they do, what can they do about it?
Mars had to throw some spanner into the works somehow and they knew it.
{cursory glance at sciencey papers}
Hmm, looks like potatoes would like some methane-induced bacteria. Poor ponies need to change their diet.
Of course, this all depends on scale. To much of a good thing is still a bad thing for the potatoes.
8873352
Nah, with the multiplication of methane-eating bacteria I guess we're going to see a drop in O2 and a rise in CO2. If they don't notice early enough someone working on the farm might drop unconscious and suffocate.
8873372
8873370
as i say before that cave from is not really lost, in fact they could used this to help them build new fuel, as a coal miner once say to me "If there burning hot water there's oil near by"
8873372
I think they'll catch it fairly early. Cherry will notice the change in the plants, and Spitfire will notice the change in the air.
The big question is what can they do about it? Fixing it might be a cost they can't afford right now, since the only possibility is magic.
Aw, I liked the farm
Luckily it's not metal-eating bacteria...right?
Oh no.
Marstronauts are going to be killed by a space fart.
Welcome to the Rescue Draft...
the Maretain Castaways are now on the clock
Weir's process of writing the Martian was, generally speaking, two steps:
1. Find a way to plausibly send people to Mars.
2. Fuck with them.
And I really enjoy the return of this process here.
Oh poodles.
How much of the alfalfa crop is going to be lost due to toxic bactreia infection, how much to sulphide die off, and given not just methane but hydrogen sulphide is a combustible and the more rigid and strong the chamber like a rocket engine, the far more powerful is the exhaust through the weakest point, the airlock. If the reaction chamber survives the shock of deflagration? If it does, is there anything further down th magma chamber that would react to having a sudden massive pressure, temperature spike rammed down it?
Its going to be an early starving run away from that locations thats about to go Yellowstone on them?
Thunderspuds are Go.
They only actually need to get Starlight Glimmer to Earth, right? Once she's in an environment with enough magic to create a proper beacon, rescuing everyone else will become much easier.
Got it, this makes sense.
These numbers are in what unit?
This mav is loaded now. Fuel, passengers, sparkle drive. Unless they can remove enough weight to compensate
AT least 19,397 kg of fuel is gonna do something. Martian mark only remove 5000 kg from the ascend stage The current plan(as we as readers see it) removes less, ads more. What can he drop? An dropping another engine is probably possible. Beyond that?
What could he remove from the descent stage? Fuel production plant. Some aerodynamic parts. anything else?
I don't think 1.2g is realistic here.
And abort to where with what fuel and what purpose?
8873436
If SG was the only one who left they would have to go back to mars and pick up everyone else.
Damn you, Mars! Just because there hasn't been a war big enough to sate your bloodlust in decades doesn't mean you get to murder marooned astronauts!
Thunderspud One, you do not have clearance to taxi. I repeat, you do NOT have clearance to taxi. Please return to the gate immediately, over
I wonder what you can do with Methane. If I remember correctly it isn't that good a burn, but who knows what they can "refine" it into.
Also, if you read this now, its T-3 minutes on the next spaceX launch. Tune in live!
Watch that hoofslam!
Update: Successful landing on Of course i still love you. Those hoverslams are just cool.
Stage 2 with exoplanet-hunter TESS is still on its way.
Update: Result: Successful launch Yay
8873453 Forty-four tons includes all of it, including the normal fuel load. As for what will be dropped, that will remain to be seen much later in the story.
And yeah, I'll have to edit out Descent Abort to Orbit. I forgot that the upper stages land without any fuel.
As for 1.2 g being realistic, it needs that much at least to LAND without smashing. The first ascent stage normally puts out a lot more than that. But then, the ascent stages are aiming at middle to high Martian orbit to rendezvous with Hermes, not at escape velocity.
Things will need to be planned.
So, I just figured out how Mark is going to die. It won't be from a methane explosion, a catastrophic decompression, or from some other sort of accident.
After days and days and days of being subjected to countless disco sing-a-longs by the ponies while en route to the Crater and Thunderspud I, Mark will probably be liable to off himself. Imagine the longest car trip of your life, and everyone in the car is continually singing the songs you hate. Then put yourself on Mars, where you can't even lower the window to try and drown out the noise.
Wait just a moment, NASA. I think you've overlooked something very important. The Sparkle drive doesn't generate thrust. It teleports, and it's been established that teleportation preserves momentum.
That has some very important implications when attempting to escape a gravity well.
8873378
Well, the thought that comes to mind, for me at least, is to take the Atmospheric Regulator from the Hab and bring it into the cave. At the very least, it should be able to pull out the methane in the air. The atmosphere in the Hab is more-or-less auto-regulated thanks to the pony suits air exchange system.
The only issue I can see is getting it from the Hab to the cave. In the book, it could be disassembled, so in theory, they could bring the pieces, and assemble it at the cave; since at this time they aren't planning on how to get it into the rover for the trip to the Crater, they don't have to worry about taking the roof off in order to transport it.
8873535
What unit are those 44 tons? If that's 44 000 kg then 53 000 kg of thrust will get s thrust to weight of 3/1 That's not what you wrote. Can't be newtons because the numbers don't work.
As for 1.2, thats realistic for landing. Not for takeoff after refueling because mass/weight increased while thrust remained the same.
8873507 As if the vertical landing at sea weren't enough, that ship name gets me every time.
Okay, my first approximation solution is to drill deep holes to give the methane tunnels to vent into, and then light fires on top of them.
Also, I just have to say, Celestia? This is what you get for neglecting the magical education of Earth Ponies and Pegasii. Being able to not only intuit but actually detect and quantify atmospheric gas concentrations and the structure and composition of soil (and it's bacteria) should be exactly what their magic is good for! But no, had to focus on the gifted unicorns...
8873542
I don't think it's exactly the same, just similar.
8873559 Since when is 53:44 equal to 5:2?
As for the weight thing, yeah, another mea culpa there, but that one gets left in for Venkat to be corrected on when Bruce Ng finalizes the MAV mods.
8873580
Yup, and TESS is cool too, and those orbital maneuvers it needs to do to get into position are something special. First in this kind of orbit!
8873621
Well, If you have 44 tons of mass, thats a weight of 163284000 Newtons on mars.
53 tons of thrust gets you 519930000 Newtons of thrust.
That's 3.18 not 2.51 (don't know how i got that)
Why? Because engine thrust in mass units is always relative to earth. Unless convention changed in the next decade.
Example from history: Apollo 11
Lunar module 35 000 pounds
Lunar module descent engine thrust: throttled between 1,000 and 10,000 pounds
8873558
That might help with the air, but since they're already recycling the air and water through Equestria (assuming I'm remembering the story right. It's been a while since I went back and read the early chapters), that's not the biggest concern.
The really big problem is what it's doing to the soil and the plants. That's the part they need to fix. Losing the plants means not only losing their food supply, it also means losing their biggest source of magic, and likely the only hope they have of making enough batteries for the Friendship's engines and the new Sparkle Drive. If they don't come up with some way to fix this fast they're going to be in a lot of trouble.
Other people have pointed out that the potatoes might survive, at least for a while, so they might not be completely screwed for magic, but as Mark has mentioned on multiple occasions, the ponies need that alfalfa to keep their nutrition at least close enough to healthy for them to make it to rescue.
Does NASA know the ponies can manipulate matter on the atomic scale yet?
Oh god, nopony considered this yet: Methane could destroy the air recycling crystal. It can't do fuels.
8873436
Here is a thought. Wouldn't it possible for SG to explain the teleportation spell to humans and have them use it one way? I imagine such a spell would require a ton of magic (I'm confident humans would be able to cobble together a primitive magical conduit that can tap into the vast stores of magic generated by the terran biosphere) and the ability to precising calculate where the teleported object would appear (humans have that in spades.
Probably won't be able to send anything from Mars to Earth but should be sufficient to at least send raw material and supplies to Mark and the equestrians.
8873436
Can you imagine the ramifications if the plan became "Just get Starlight to Earth, and trust the Equestrian's to get the rest home once Starlight can signal them."
8873542
The preservation of momentum is interesting. They could forgo rockets by teleporting up and then just falling to generate velocity. Do this several times to get up to orbital velocity, then teleport sideways so that the momentum puts the ship in an orbital trajectory. A similar method can be used to slow the ship down.
8873776
I guess nobody wants to be going straight at a planet, repeatedly, at orbital velocities, hoping an experimental sparkle drive will save them. I wouldn't either.
Martian potato famine?
8873674
If the rule "what you send may arrive at lower enthalpy state" is working, then methane is ok (separate from oxygen, obviously). Something even a tiny bit more complex is not ok, though (ethane and methanol for example).
Hmm, now I realize that I haven't yet checked if sending air is ok (because of nitrogen oxides)
i just looked up thunderspud and now regret it
8873820
Aw fuck! That's what it looks like to me.
Next time on Mars Farts...