The Maretian

by Kris Overstreet

Sol 217

Venkat's brain still sensed the world through a blanket of jet lag, compounded with the exhaustion of traveling halfway around the world. But the job of Project Ares director didn't stop. Thus, only sixteen hours after he had been poured into his bed by a wife he really didn’t deserve, he stood in the doorway to his office, ready to catch up on the work that hadn’t been able to follow him to China.

And he continued to stand there, staring at the five people- three men and two women- who had beat him into his own office. That, and the neat stack of paper next to them on his desk that looked like three or four reams of office paper, unwrapped and piled together. ”Let me guess,” he said. “You’ve discovered another Rich Purnell.”

“Nope.” The voice triggered recognition; the woman speaking was the one who’d taken charge of the Project Sirius tiger team discussions. “Rich Purnell was one guy. This,” she slapped the top of the stack of paper, “took over a hundred people to develop.”

“That’s nice,” said Venkat, for whom a tall venti hadn’t been nearly enough caffeine this morning. “What is it?”

“This,” the woman said, “is what Mark Watney and the aliens have to do to get to Schiaparelli. In detail. Step by step. Complete with suggested alternatives and workarounds if our assumptions of the alien ship turn out to be inaccurate.”

“And the sooner we send all of this to him,” one of the male engineers added, “the better.”

Venkat sighed. It took a motion of his hand to get them to step aside so he could get behind his desk. He dropped his briefcase, slumped into his chair, and said, “Okay, walk me- no.” He powered his computer on, and while waiting for the boot-up process to complete itself, he said, “We’re only three hours ahead of Mars time today. You can walk Watney and his friends through the process yourselves.”

AMICITAS FLIGHT THREE – MISSION DAY 219
ARES III SOL 217

[07:24] JPL: Good morning, everybody! This is Venkat Kapoor, back from China. The Chinese people send you their love and good wishes. How is everybody?

[07:52] WATNEY: Mostly good. Cherry, Spitfire and Fireball are preparing to go to the cave. Hay harvest is in a couple of days, with the potato harvest a few sols later. Starlight and Dragonfly are helping me with Hab maintenance, with the main task being reconditioning the water reclaimer wastewater holding tank. Nobody’s risked injury or death in, oh, whole days now. How’s by you?

[08:18] JPL: Tired from the flight back from China, but working hard on your problems. With that in mind, Mark, I’m handing this computer over to some very smart people who have worked out the details for building what you called the “Whinnybago”. They’re going to give you broad outlines. After that we’re sending you the actual procedures. It should tell you how much work they’ve gone through that the procedures document will likely eat up all available bandwidth for the rest of the day and possibly into tomorrow.

[08:22] JPL: Good morning, Mark. I’m Jennifer Laurence. I’m a senior systems engineer in the Engineering Directorate at JSC. With me are personnel from Astroresources, the EVA office, and Flight Operations. I’ve been chosen as spokesperson for the Sirius Tiger Team.

[08:25] JPL: We’ve spent weeks working on the best way to modify your rovers and the alien ship to get you across Arabia Terra to Schiaparelli Crater. What follows isn’t what we want to tell you; it’s what we have to tell you. This is the best solution we could find out of a lot of rather bad ones. So please be understanding about what you’re about to read.

[08:34] JPL: The main point we worked with is that the cabin space of both rovers isn’t sufficient to carry the six of you and the food you would need for up to 150 days away from the Hab and up to seven in the MAV. And that’s leaving aside the materials, tools, Sparkle Drive, and whatever else you need to make the MAV into something that can get you off Mars and to safety.

So from the beginning we’ve worked on the assumption that we would convert Rover 1 into a trailer with the Rover 1 pressure chamber removed and the forward half of the alien ship mounted onto the chassis in its place. In order to make this work the ship will have to be mounted backwards, with what you call the habitat section facing Rover 2 and the nose section hanging off the back. You’ll need to mount both spare rover wheels on the alien forward landing gear to support the weight. Dr. Kapoor told you this when we began.

The main problem is, our best estimate shows that the trailer, empty and trimmed, weighs not less than twenty tons. We can’t make it any lighter than that using the mock-ups here. One rover could just barely tow a dead load of that weight on a paved highway with not worse than a five degree grade, conditions which exist precisely nowhere on Mars. That means all eight wheels on the two rover chassis will have to be powered. We think we can get away with releasing the clutches on the wheels you put on the landing gear and leaving them unpowered, but that's the only power savings to be had for wheels.

The good news is the heating system you improvised for the Pathfinder trip is just about enough to substitute for all heating systems, which would give a normal unloaded rover tandem system, all eight wheels under power, a range of about seventy kilometers on the flat. But our tests here on Earth show you get only about forty kilometers before the rover batteries run out of juice. Mind you, that’s with the batteries running nothing but the motors, the interior lights, air circulation, controls and computer. (Martian gravity might be less, but the inertia of moving a load from a standing start is the same on any planet.)

So electricity and weight are our two biggest obstacles.

[08:41] JPL: Our limitations for electricity are simple: how much storage capacity can you carry, and how much recharge capacity? Your limiting factor is going to be sunlight. By the time you travel it’ll be autumn, with about eleven hours per day of usable sunlight for solar cells.

On the other hand, we want to reduce your weight. Aside from trimming everything possible from your rovers and the alien ship, the only thing we can do in that department is shorten your travel time and save on food.

Straight-line distance is about 3200 kilometers, and a more reasonable actual driving distance would be 3500. At forty kilometers per day that would take you eighty-eight sols, which is less than our initial 100-sol estimate but still far too long. Our goal is seventy kilometers per day, for fifty days of transit. Based on our initial travel time estimate of 100 days, seventy kilometers per day saves you over half a ton of food, which is important considering how very heavy your total load is.

So that’s where we are- looking for the dead minimum load that can travel seventy kilometers per day and recharge appropriately. That’s what we’ve spent weeks experimenting with to make happen.

[08:44] WATNEY: Hello, very smart people! What have you got for me? I hope you don’t mind if I work while you talk, but the message turnaround is fifty minutes.

[08:45] JPL: With that in mind, we abandoned all thoughts of taking the life support systems from the Hab. The equipment weighs over a third of a ton not counting tanks and expendables, and the energy consumption for six people is simply too high for a mobile platform to sustain. You’ll have to rely on the alien life support systems. It’s absolutely vital that you preserve that system from harm at all costs.

But with that system plus the alien space suits, the Sirius tandem (we voted againt “Whinnybago” here, so we’re calling it Sirius tandem rover) will have air, water, and heat at zero energy cost. That means we can budget ninety percent of the electrical power to movement. and ten percent for everything else.

[08:47] WATNEY: Sure, lay it on me. I’ll wait until you’re done.

[08:51] JPL: Under that budget, the normal two rover batteries and their 18 kilowatt hours per sol would only be good enough for thirty-six kilometers per day. (Our road tests didn’t take into account overnight power costs.) We need to double that. That means stealing three of the remaining hydrogen fuel cells from the Hab. To make that work, the on-board alien ship batteries, which you described as “right out of a U-boat”, need to be removed, as will the passenger bench from Rover 2. Depending on the size and shape of the alien batteries (which are probably heavier than a fuel cell and definitely provide less storage), you can put the odd battery in either place.

That provides 45 kilowatt hours per sol of storage and over eighty kilometers on flat ground of travel range. That amount of power requires the same or greater recharge capacity. Based on your Pathfinder trip, fourteen solar panels was enough to provide 18 kilowatt hours per sol of recharge in twelve hours, counting dusk. Each Hab solar farm panel provides, mid-range, 120 watts per hour during good daylight conditions, for an estimated total 1.3 kilowatt hours per sol. That requires thirty-five solar panels total.

The good news is, even after cutting down the alien ship, our measurements show it to be wide enough to accommodate two rows of solar panels up to the front of the pressure chamber and one row along the nose, all mounted permanently to the roof. The removal of the ship’s outer skin provides ample mounting points and hardware to secure them properly, and the same adapter you’ve used to connect the ship to Hab power can be used to wire the panels directly into the Sirius tandem rover electrical system. Based on that, we estimate you can carry twenty-eight solar panels on the finished trailer alone. The remaining panels, plus whatever surplus you think you can accommodate, will be used as you used them on the Pathfinder trip, carried on the roof in a single stack next to Pathfinder. Procedures on mounting both are in the final report.

[08:56] JPL: That solves the power problem. The other problem is weight. The trailer is already excessively heavy, so we want to limit what else goes into it. Balancing the load between the two chassis will increase efficiency. It should be used for habitat, storage of things that can’t withstand vacuum, the Sparkle Drive core, and as little else as possible. Everything else will have to be stuffed into or onto the rover. That means you’ll have to recycle one of the emergency pop-tents to use its canvas to expand and strengthen your saddlebag arrangement so the extra weight of food, tools, etc. is spread more evenly around the rover’s pressure vessel to prevent its collapsing.

The heaviest things are the alien engines. Those will have to be mounted on the sides of the rover, along with a basket to hold alien batteries and thruster packs. We have a procedure for that as well. It’s ugly, but it won’t touch the pressure vessel- it’ll mount to the chassis as close as possible.

[09:01] JPL: One final note: the Sirius tandem will be tall with a high center of mass, especially in the trailer. To be blunt, it’s tippy as hell. Also, the rover suspension is being stressed past its rating, especially on dynamic loads. At a rough estimate, the total weight of your rig, loaded, with food and passengers, will be thirty-eight tons, twenty-four of which will be the trailer. The manufacturer of the rovers absolutely refuses to sign off on this load. And do I even need to talk about the brakes?

Careful driving is mission critical. Hitting a hole or rock at speed could roll the tandem rover or cause a suspension component to shear. We recommend, if the aliens are willing, that they EVA well ahead of the rover and clear the path of rocks between 20 centimeters and 60 centimeters in height. Boulders taller than 60 centimeters should be avoided whenever possible. Otherwise, we recommend a maximum of two crew in Rover 2, with the remainder either on scout duty or in the trailer.

Those are the high points. Do you have any questions?

[09:29] WATNEY: Thirty-six tons, huh? Well, at least I won’t be pulled over by the Martian Department of Public Safety for an overweight load.

“Kilowatt hours per sol” sounds clumsy. Doesn’t that unit have a name of some kind?

How do I link the life support systems of the alien ship and the rovers? Ditto the electrical systems?

Did you say carry the food outside the rover, in the saddlebags? I just want to be clear on that, that you’re proposing we turn the rover into a rolling food truck for all those snooty foodie hipster Martians out there. Do the procedures include a sign for “Watney and Company’s Home-Grown Taters and Sprouts”?

And finally, “Whinnybago” is a fine name. “Tandem rover” is boring. Next you’ll be calling the Astros the Houston People Who Mostly Fail at Hitting a Piece of Leather and Twine with a Stick.

[09:58] JPL: If the Martian fuzz pull you over, we’ll pay the ticket.

Kilowatt hours per sol sounds fine to us. If you don’t like it, suggest a better name.

Check with the alien engineer and verify that the charging port on the exterior is robust enough to handle the full load of a 45 kilowatt system. It should be. If so, run cables from the tow-hook of the Rover 1 chassis up to the port. Cannibalizing the Rover 1 pressure vessel, plus use of solar farm cables, will provide what you need. Connecting air will be a bit trickier, but it boils down to drilling two holes in the alien pressure vessel, sealing the air cross-feed lines into it, and connecting the air circulation system from Rover 1’s environmental systems to the other side.

The Sirius tandem rover is not licensed for retail sales in any Martian jurisdiction, so no sign is necessary. We do advise you watch out for Martian bears, particularly if they wear hats and/or ties.

And I don’t concern myself with sportsball matters. What other people call the Astros is their problem. But we’re calling what you’re building the Sirius tandem rover.

[10:23] WATNEY: A female engineer with a sense of humor. Marry me.

[10:48] JPL: I’m twelve years older than you are. Talk to me when the aliens give you a time machine. But beware of my ex-husband.

[10:50] JPL: Venkat here. I think we can go ahead with sending the procedure now. Looking forward to hearing about the harvest, Mark. Good luck.

Author's Note:

This chapter (and the next) is me mostly nailing down the order of things.

If you've seen the movie but not read the book, having NASA give chapter and verse on how to mod the rover seems perfectly natural to you. But in the book Mark loses Pathfinder to an electrical accident on Sol 197 and has to work out very nearly all the procedures for making a two-rover rig that will sustain him for a hundred sols by himself. It's not the liveliest section of the book (which might explain why, after Hermes gets resupplied, Andy Weir has a 150-sol timeskip), but it has some clever moments.

Alas, one of those is not likely to surface here. Since NASA is doing the number crunching, and since the oxygenator, atmospheric regulator, and water reclaimer are all staying in the Hab, Mark has no real inclination to coin the electrical engineering term "pirateninja".

Anyway, this chapter marks a shift in the focus of events. We're now moving away from survival and towards actual rescue, and the time has come for our heroes to begin the preparations for that event. I'll try to make this interesting, but beyond a certain point I'll be skipping sols again for lack of anything interesting happening.

Jennifer Laurence is an original character, not in the novel. Weir really tended to mish-mash how NASA is organized to minimize the number of named characters. JPL, for example, would not be the sole place that all Mars probes were built in a real Ares program. I'm trying to correct that a little, but not so much that it bogs down the narrative.

By the way, when Jennifer says "on the flat" she's not kidding. JSC is about ten to twelve feet above mean sea level, if that, and the land is flat like a pancake for many, many miles. JSC does have a small rock-climbing hill that it used to test smaller rovers, but nothing of a size to test a tandem vehicle over twenty meters long.

Anyone inclined to complain that the electrical expenditure for travel for this weight is far too optimistic: I'm not interested. Looking at various numbers in the book, I'm pretty sure Weir just juggled numbers to turn them from "can't make it" to "can make it". I'm doing the same, because saying, "If you carry the whole damn Hab solar farm you still won't make it in time," isn't going to make for a fun story. This is one of those times when engineering must give way to storytelling.

I either have one standard-length chapter or two short ones in the buffer. I may try to stretch the second one a bit tomorrow, or I may move on.

Comments

[Georg]

"...the cabin space of both rovers isn’t sufficient to carry the six of you and the food..." -- Well, Dragonfly can carry all the food inside. The rest of them however might have their taters and alfalfa snacks in a pop-up glued to the tail end of one of the vehicles.

Can the alien ship wheels be used in addition to the rover wheels on the back as unpowered 'duelies' perhaps? Thus making the Whinnybago a front wheel drive RV.

[Halfdemonpyro]

76,000 lbs. Nearly a fully loaded semi-truck (lorrie for the english folk) on unpaved, un graded, horrid surface with a fragile rig....

[KMCA]

Too bad there's no way to get a magic battery boost to the wheels. Even at 2% a generation they could probably afford to give a boost near the beginning of the trip and have it recharge before arrival... But as a reader I have a feeling that Dfly will need that magic to maintain sanity.
Poor filly.

[TheTownCrier]

Wait till he gets a load of the steps involved. Daunting comes to mind.

[Night_Moon60606]

somehow, i dont think Watney and Co. will have to worry about anybeing smarter than the avvvverage Marain Bear....

[Kris Overstreet]

8903911 There is- Amicitas has a magic-to-electricity converter. But that process isn't two-way, and once they leave the Hab and cave farm behind magic is going to be at an absolute premium.

8903908 Look on the bright side. Nobody riding your blind spot for twenty miles, nobody swerving around you and slamming on their brakes right in front of you, no other trucker ahead of you going 55 trying to pass someone going 54 1/2...

[Halfdemonpyro]

8903921
Very good points here.

[Shadow Star]

doing things with rover to make trip..

bah brain pain. too much technobabble for 1 am.

[LordBucket]

So electricity and weight are our two biggest obstacles.

Some thoughts for consideration:

* While it's been established that conversion of electricity to magic is an unsolved problem, On Sol 102 Starlight stated that the conversion of magic to electricity is extremely favorable. This would seem to imply that she can recharge electrical batteries during their journey, by converting magic from the magic batteries they're carrying with them...which will recharge over time.

* As an aside, in addition to to Starlight, they also happen to have another magic-to-electricity conversion device: Spitfire. She's a pegasus, and water to create moisture is something they can teleport in with no additional weight requirement.

* Given the amount of time involved, they could plausibly send somebody to make an advance trip to drop off extra magic batteries along their trip somewhere, and then drive back...and then when they actually go to leave, stop to recharge from the batteries left behind on the first trip.

* Dragonfly can put ponies in changeling cocoons, resulting in reduced food weight requirement due to hibernation, as well as a much more comfortable trip for those dreaming of home instead of living in a cramped space for over a month.

[Zobeid]

I would like to see somebody draw this contraption as it has been described. It sounds pretty funky.

[Scarheart]

So... A tank. Neat!

[Caliaponia]

kilowatt-hours per-sol. Kips?

[forbloodysummer]

Meanwhile, Whinnybago drew closer...

Also, it's a big tractor and much bigger trailer going across a red desert on both a planet and a mission named after different gods of war. We can take a leaf out of Furiosa's book and call it the War Rig.

And the line about Venkat being poured into bed by a wife he didn't deserve was ever so sweet

[titanhades70]

SG: Yeah.... time travel.... about that.....don't really need a machine..

Man, when they find out about that little ability of Starlight. ....

And most likely her crew mates wouldn't know either...

[helix37]

I'm kind of wondering if they've managed an electrical configuration that can let them use the solar panels during travel. I mean 28 solar panels arrayed on the roof of the Amicitas the whole time is a pretty sizeable power generation over the couple daylight hours they're traveling for. When Watney did it himself it was pretty inconsequential since the rovers didn't have space for nearly as many panels to be visible and they had to be stacked and spread repeatedly. It's a very different circumstance here, and those extra kilowatt hours they could gain by doing so could be quite significant.

I'm also somewhat surprised they didn't end up doing Watney's idea of taking a rover out in advance and leaving a food supply cache along the route to lighten the load a bit on the early part of the trip.

Having the ponies Eva and clear the path ahead is pretty good thinking. Though I'd have been tempted to have Fireball get out and push. He had sufficient strength to lift up a corner of Amicitas before it was cut up, which is some pretty incredible strength. Amicitas is likely half that weight after all the skin and the engineering section were cut off. So his pushing power would likely be a significant contributor to their motive force.

[Bahamuttone]

That provides 45 kilowatts per sol

kilowatt-hours

[FredMSloniker]

Wouldn't kilowatt hours per sol just be... well, not kilowatts, but something that could be converted into kilowatts?

[Bahamuttone]

8903936
Magic regenerates only in a ambient full of life. The trip would be bare minimum so no dice.
The batteries are a premium commodity they don't have enough to just disperse on the planet
The cocooning may be a decent idea... but means having lesse people to do things and has definite unfortunate implications.

[titanhades70]

8904019
You know, most if this coccon stuff sounds like fan invented stuff. I keep up to date on the show and the comics and don't rember any of this about the coccons. Is it stuff created in his first story for his stories?

[Gym Quirk]

8903936

* As an aside, in addition to to Starlight, they also happen to have another magic-to-electricity conversion device: Spitfire. She's a pegasus, and water create moisture is something they can teleport in with no additional weight requirement.

Setting aside the problems of trying to harness an indoor lightning discharge as a means of electricity generation, how many mana batteries are you going to drain to achieve the requisite cloud manipulation and so on?

(I presume it was the lightning you were thinking of. Petting/brushing manes and so on in low-humidity to generate static electricity may have its attractions, but is rather inefficient... )

[Bahamuttone]

8904021
That the cocoon are relaxing is from Changeling Space Program, yes.
The cocoons shows up a couple of times in the show, no mention of how you feel inside one is made, except that Celestia wakes up inside one and appear startled by it https://www.youtube.com/watch?v=LogTDQMDSKc

[zsewqthewolf]

i wonder there going to make a song of them building. "oh we build build build all day long as we fix fix fix fix the problems a head" thats all i can get on top of my head for it

[Production Run]

If any engineering issue can be explained away by "it's the future," the capabilities of electric motors and batteries can. Electric vehicle technology is advancing very quickly, and it's not unreasonable to think we might have something as good as what the Ares rovers have by the time the missions are supposed to happen.

[kitsune5000]

8904010
I would just have starlight trailing behind (or on top) with a battery to catch the rover if it starts to tip.

[Batling]

You know, Dragonfly's increasing magic deprivation could throw a wrench in all of this, especially if her condition is worsening. If she is going to start requiring more and more "maintenance" inside an unleashed battery's magical field, that might not be something they can provide on the trip considering their ability to recharge batteries will drop to near-nothing if they have to leave the cave behind.

[Hiver]

8903989

pirate-ninja.

The proper term for kilowatt-hours per-sol is clearly pirate-ninja.

[Panem et Circenses]

8903921
“Kilowatt hours per sol” is clumsy, I agree.
How about a ‘Wattney’?

[Dogman15]

8904005
First I went here: http://the-martian.wikia.com/wiki/Rich_Purnell_Maneuver
Then I clicked the image: http://the-martian.wikia.com/wiki/File:The_Martian_Route_2.jpg
On that image, it says "To see Andy Weir's original trajectories, visit galactanet.com/martian/hermes.mp4"

[Bugsydor]

Alas, poor Pirateninja. A true prince among units. We knew thee well.

[Sweetblue]

Well, you could easily make a cop-out on those numbers by making Starlight cast some friction removal spell on the wheels. That should reduce the power consumptiom all kinds of ways.

[NotMyUsualUsername]

8904251
Erm, how are they supposed to move if they have no friction? That's removing their ability to have grip on a surface.
The only place that could be relevant is removing the friction from the ball bearings or whatever it is they use, but I imagine the difference would be pretty minimal.

[PiMan]

8904016
I was thinking much the same. A sol is just a number of hours, so kWh per sol is [power × time ÷ time].

[Prawo Jazdy]

8904010
There's the questions of whether Fireball can push for longer than a few minutes per day (I can imagine a half-hour spread across a sol in chunks), and wouldn't that energy need replenishing, or be better spent clearing rocks as needed.

8903936
Agreeing with Bahamuttone that magic batteries don't recharge away from life--certainly not quickly around six animals and zero plants.

I think to achieve the best weight savings in terms of just batteries, they'd have to cache fully-charged batteries ahead on the trail (at some maximum distance), spend some magic electrically juicing the appropriate wheels, chuck each empty in sequence (unless more than one battery at a time gives better power), and after the last dump (to be followed by the last, and presumably only, pickup), stop juicing the wheels.

Heck. If their rations before picking up the last cache amount to more than the weight of a battery (what, 70kg?), that's almost a free battery. They're trading off a late period of reduced weight from food already eaten for an early period of carrying an almost-full load faster than usual, plus a battery for the modifications. So... what are the numbers on magic batteries providing electricity?

[azeazezar]

8904010
Don't forget to cover the bottom of the contraption. They
have a sun relay crystal!
Also, having the ponies walk ahead sounds like a bad idea to me.
The unrepairable parts of the EVA suits will wear out.
8904312
If it is just as efficient as the magic engines, somewhere around:
400 000 joules, or 0.1 kwh

[Cpt Creampuff]

Things I'm excited for
1. The trip (here hoping for another accidental snuggling episode between mark and starlight)
2. Them getting on the hermes if that happens and the hermes crew reaction to the pony crew

[ocelloid]

Jennifer Laurence is an original character, not in the novel.

So, a person named Laurence is going to walk them through Terra Arabia.
I see what you did there and I like it.
Also, congrats on 1k likes!

[Alondro]

My question is: how Is Dragonfly going to feel when the plants in the cave start pleading for help as they die.

"I am dying. Please help me."

And the ambient hate on Mars begins laughing, "I am death. I come for you! I AM SATAN!!"

And then of course the Death Box chimes in, "I hear, my lord, and I obey." And then it starts to melt itself down through pure, concentrated evil.

I could reaaaaaaaaaally send the poor bug into a mental breakdown.

[Alondro]

Careful driving is mission critical. Hitting a hole or rock at speed could roll the tandem rover or cause a suspension component to shear.

They should complain to the Martian road maintenance department for the shoddy condition of the highways.

i.pinimg.com/736x/02/b3/0a/02b30aa74d7ccfe63d12173da8e46b84--the-martian-he-he.jpg

Oh... right... they're dead.

[Alondro]

8904401 I shall steal Mars for the British Empire!

[Sweetblue]

8904257

Friction causes a lot of loss in energy in cars, likely Mars rovers are different thing because they are fully electrical. And could be the % of friction loss is higher too since there are no combustion issues. But then again a minor detail.

Global energy consumption due to friction in passenger cars, transportation and industry (Source)

https://imgur.com/6prcBgV Key picture since it refuses to link properly as a picture for some reason.

[FanOfMostEverything]

We have the best possible option. No one said it was a good option, but it's the best one available. I do look forward to seeing what the Amicitas crew thinks of it.

8904006
It does seem to need the Cutie Map, which probably counts as a machine.

[ocelloid]

8904504
Can you possibly elaborate on the thermal loss? I mean, Mars isn't that cold, but those poor bastards could use any drop of heat they can get.

[Kris Overstreet]

8904547 Thermal loss, in this case, would be friction in the wheel bearings, the wheel surfaces, and other moving parts of the wheel and motor assemblies. It's basically entropy having its wicked way with the conversion of electrical or chemical energy into kinetic energy. But since the thermal loss in this case is inside the wheels, way out on the edges of the vehicle, it won't be of much use in keeping the interior warm.

[Latrans]

8904308

8904016
If you were averaging out the energy potential for the trip, this would work, however they are discussing how much total energy (KwH) they have to work with for a given unit of time (per Sol). Simplifying the notation would just require you to expand it again any time you ran some calculations.

[Prawo Jazdy]

8904378
If accurate, that sounds like it can't help much at all. Well, unless Dragonfly needs an IV drip of magic during the trip.

[kitsune5000]

8904125
The cave was giving 7% per day. Just the one human and 5 equestrians was giving 4% per day.

[ocelloid]

8904667
I was actually thinking towards thermocouple, but I'm not sure if the crew has the materials needed or if it would be efficient enough to even consider.

[Kris Overstreet]

8904766 Just noting, the cave is plants-only most of the time.

[River Babble]

I ship it. Twelve years is totally surmountable between two adults in their late 30s and 40s. :Dd