The strapwrack DOES soften up again when soaked in a tub of water! (It takes a while, since a lot of it has dried into shapes that don't fit in the bottom of the tub. NOTE TO SELF next time she should, like, wrap it into spools to store, if she's planning to let it dry for later use.) 

Merrin spends pretty much the entire rest of the day on this project, alternating with:

- Digging an additional trench beside her seawater-evaporation pit, and rigging up a more efficient freshwater-collection system. She sacrifices a set of IV tubing to it, which makes it pretty easy to also attach a 1L IV bag for the actual collection - its existing contents can be mixed with her remaining freshwater, it's not very salty compared to seawater and she could probably use the electrolytes anyway.  

- Actually pulling up her camera recording on her screen and figuring out what setting to use to turn 4 hours 19 minutes of video into a file resembling one of those timelapse night-sky images with star trails. It turns out the software actually ALSO has a setting to just find the celestial pole for her! Merrin had forgotten it did that! She...spends a kind of annoying length of time figuring out exactly what direction her feet were facing and doing adjustment calculations and figuring out where true north is from here (it's unsurprisingly not identical to magnetic north, she calculates a declination of 11 degrees).

- Re-setting-up a sundial apparatus, this time actually facing true/celestial north. Her measurements will be imperfectly comparable to yesterday's, but from now on out she's staying put.

- Walking back to check on her solar cells, and retrieving one of the 500 Wh auxiliary cells, now filled up. She should fill up another over the afternoon. 

- Eating two more meal bars. 

- Taking a 3h nap

It comes out really nicely. It looks so cozy! 

And she's promptly going to make it much less pretty-looking by sacrificing two of her insulated-reflective emergency blankets for the cause. Both are reflective-side-in, but one is on the outside and one is on the inside, leaving a small air gap in between for its additional insulating properties. 

It's worth cutting them for this – very, very carefully, after sketching out her plan on notebook paper and carefully drawing her planned cuts in indelible marker on the blankets.

She has a basic sewing kit. She also has duct tape*.

That part takes four hours, but at the end of it she has a pod that will fit one (1) Merrin, in a sleeping bag, optionally still in her armor. Her sleeping pad fits perfectly into the flat bottom. 

And it's still probably three hours before sunset. 

(It's highly optimized Exception Handling general-purpose extra-tough extra-sticky utility tape, but that's basically duct tape.) 

...She'll spend her remaining three hours of light sitting in the back of her cave - where it is, in fact, a lovely comfortable temperature despite the high slowly dropping from 29° C outside - with her electronic screen up at minimum-backlight. She tapes four squares of notebook gridline paper together and, using a storage crate as a desk, copies over a star chart and names some constellations. 

Merrin does it out of the suit, breathing the ambient air; the temperature in her shaded cave did rise with the heat of the day, since she didn't have the flaps sealed and was in and out a bunch, but only up to a very pleasant 18° C now very slowly dropping, despite the outside temperature having hit almost 30° C today.

She feels...more or less completely normal? Well, once you account for the fact that it's now been, like, six and a half days in dath ilani reckoning since she last had a conversation with another human being and she's spent nearly all of that time agonizing over the dwindling power supply she needs for very basic Staying Alive. But she's satting mostly at 89-90% while at rest, and her resting heart rate is actually getting back down to 62 even while she's still awake and working, with good heart rate variability according to the suit analytics. However stressed she is, she's not actually running stupidly high cortisol levels right now. All the physical labor is probably helping. 

And shortly before sunset she dons the suit again and treks back over to the last remaining sign of her old campsite: the solar unit sitting by itself, a startlingly out-of-place piece of advanced technology, sitting there in an expanse of bleached and weathered limestone, on a planet where the most advanced terrestrial life consists of tiny segmented worms about the size of an individual suture needle. (Merrin spotted them when she was digging for her still.) 

The angle-auto-adjust feature worked well, and it was another clear day. She's gotten nearly 1040 Wh; the unit appropriately switched the relay over and started charging the third backup battery after the second was full. 

She carefully folds up the solar unit and carries everything back to camp. 

And back. The sun is down (she checks and memorizes the exact time, since her hands are full of solar unit, she didn't bother bringing the extra weight of its storage crate to clip on her back), but she has enough twilight to make it to camp before she can't see her feet.

...She can afford a bit of artificial lighting tonight, she decides, to sit in her cave and review her current status on all of her critical numbers. 

Her power armor is down to 290W of charge. It was a less heavy-exertion day, mostly work with her hands that didn't rely on the suit's servos, but it was, still, a long day, and for quite a lot of it she was using the climate control. 

BUT she actually has more than half of her O2 tank left from the midmorning refill. 315L. ...Which wouldn't quite stretch to cover the whole night, but she does, in fact, think that she's not going to give herself any medical problems if she sleeps without supplementary oxygen. 

Between her main battery, charged auxiliary cells, and the charge left on her armor, she has about 1800 Wh. (She's actually going to top up her suit battery immediately from the auxiliary battery that only got to 40 Wh, the transfer is pretty efficient so the loss is low and that way she can neatly separate out "full" and "empty" backup batteries. 

...She should check her records of daylight hours yesterday versus today. 

Even accounting for measurement error, it sure looks like today's sunrise-sunset interval was somewhere between ten and twenty minutes longer than yesterday.

It's spring. 

...Correction: it's very likely to be sometime after the winter solstice and before the spring equinox. But she doesn't know what percentage of the way she is from one to the other.

Or, come to think of it, how long the year is. She can calculate that, with a few more reliable data points on the changing sun angle and a lot of really annoying geometry. 

…She can trivially check her latitude, though. The software probably calculated it for her, it’s literally just the angle of the celestial north point above the horizon.

44 degrees north, apparently. Almost exactly halfway from the equator to the poles. 

SO MUCH MATH 

But: in the near term, it’s closer to good news than bad.

The days will get longer. The sun will get higher in the sky. Her per-day solar panel production will increase: eventually, she might be able to charge her suit to full every day. 

The ocean will get (a little bit) warmer. The nights will be more survivable, though given that even a summer night is probably not much less than 24 hours, she wouldn’t be surprised if even summer nights drop to below freezing. 

The daytime highs will be a problem, but…thanks to her lovely cave which she loves, not for a while. She can get it better sealed than it is now; she’ll design a structure she can make out of strapwrack. There are clearly deeper caves; maybe she can find some that aren’t too hazardous, and retreat to them during peak afternoon temperatures.

Food is a problem.

(Water is still not optimal, but it’s less of a problem. She has 2200 ml left of today’s production from her new still, to last her through until tomorrow afternoon or whenever it starts meaningfully evaporating again. She covered it with an emergency blanket as insulation, so it might not even freeze solid if the rocks keep radiating the absorbed heat of the sun for long enough overnight.)

…Food and water are tomorrow’s problem. It’s 90 minutes after full dark, she’s been working by the dimmest, bedtime-color-mode setting on her durable and power-efficient LED-strip portable light, and her nap was now 14 hours ago. Merrin is feeling pretty ready for her first sleep block.

It's actually too warm in her sleeping capsule to be in the sleeping bag. Merrin leaves it unzipped and flops on top of it and almost immediately falls asleep. 

Outside her sheltered cave, the temperature drops.

Inside the cave, the temperature also drops, but more slowly. She's thoroughly tucked out of the wind. The rock above her absorbed significant daytime heat, and now re-radiates it slowly. The deeper bedrock neither heats up nor cools down much with the daytime swings.

There's a very faint draft coming from the dark tunnel at the back of her cave. It's cold relative to the daytime outside temperature, but deep bedrock - and the air it surrounds, where there are caves - approximates the annual average temperature, and it's above freezing. Eventually, as the night goes on, that trickle of airflow becomes a warming rather than a cooling effect.

Her cave interior is eventually going to drop below zero, in the last stretch of the night, but not that far below zero. Her capsule, with the "door" flap at the head hanging down and Velcro-strip-sealed in place, is going to stay comfortably above freezing all night long. 

Merrin wakes up and checks her wrist timepiece and is informed that it's, like, 3 pm in dath ilan. She was using the timekeeping function on her power armor for her daytime timekeeping, since she was wearing it and her wrist timepiece wasn't even accessible. 

Great. She really needs to go dig into the reprogrammable-software options - which, to be clear, she has literally never done before, but it's probably set up such that a smart eight-year-old could do it, and Merrin is not smart but she's a grown adult who is capable of figuring things out even when it's really annoying. 

She vaguely recalls glancing at it at some point when she was midway through her star chart and noting that it was apparently little after midnight in dath ilan. So at a wild guess, it's been thirteen-ish hours since sunset and she's been asleep for eleven and a half hours. More than she should need, really, but she's not going to complain if her circadian rhythm is deciding it's time to adjust to the long nights. She does remember noticing that she wasn't as tired as she would naively expect, yesterday, staying up for - it must have been over 30 hours, with only that one three-hour nap, and she was only really crashing toward the end of it. 

Her circadian rhythm probably isn't going to fully adjust. She vaguely recalls reading about experiments with subjects living underground and never exposed to daylight cues, and that does often result in the 24-hour circadian rhythm stretching longer, but only rarely even as long as 48 hours. She does feel like she's sleeping enough, but she's probably going to continue to have two nighttime blocks with an annoying in-between period of lying awake in the darkness. 

She could probably justify turning on her reader tablet for a little while and reading something to pass the time, but actually Merrin is kind of inclined to instead train her Mental Discipline for Solitude With No Entertainment. If she survives long enough, eventually her electronics will stop working and she won't have a tablet to use at all. 

Seven hours pass....less painfully slowly than before. Merrin spends a lot of time mentally designing the better cave cover she can make out of strapwrack. She'll still want to use the tarp for this summer - she can't make a replacement UV-reflective surface - but if she survives the summer heat, in winter she can replace it with a whole lot of insulation made out of local materials. 

She's got time. She's got nothing but time to do arts and crafts and building with local materials, really. 

If she can solve the stupid superheated problem where she arrived with 45 days of food. Which is, like, seventeen planetary days. And she's already coming up onto day four.

Eventually (after a pee break, which is enough to notice that the interior is getting chilly but isn't even below freezing yet) she drifts back to sleep, and sleeps through until dawn. 

It's down to -3° C in her cave, but it can't have been below zero for that many hours of the night; her drinking water containers didn't freeze solid. 

It's totally safe to let them freeze - they're tough flexible plastic, and expand - but it's nice that her remaining water is drinkable straight away. Merrin is going to drink some, and eat a meal bar and try NOT to count down in her head what percentage of her remaining calories it represents, and check her O2 saturation reading. 

91%! Technically lower than expected in a healthy adult but she's fine, it's not going to be causing her any problems. Her resting heart rate taken by hand is a little higher, in the 70s, but that's actually adaptive in this phase of acclimatization. 

The more important question is going to be her exertion tolerance, so...she should do a small, controlled test of it here and now. It'll help her get warm. 

50 pushups? 

....Haha, just kidding, Merrin's body is firmly telling her after, like, twenty-six pushups that she should consider Stopping That. Her O2 saturation reading drops to 82% and takes a while to recover. She feels shockingly out of breath, completely disproportionately to the actual activity, and her heart rate is spiking a lot higher than it usually does from pushups. 

...All right, she's super not fully acclimatized.

Which makes sense, it's only been a week in dath ilan days, and she's probably delaying the process a bunch because she was paranoid about ANY cognitive impairment when she has to do constant high-stakes prioritization and gave herself extra O2 all through the first day, so really from her body's perspective she's been here for two planetary days, not three. And still giving herself some supplementary O2 in order to maintain her kind of ridiculous activity level.

Right now her body will have gotten used to breathing a bit more, her kidneys will be adjusting her bicarb levels to tolerate hyperventilation, and her body will be retaining less water to increase her relative red blood cell count, but her absolute red blood cell count is probably just at the start of its rise.

In another seven planetary days, if she slowly weans herself off using the suit and extra oxygen for walking around, she'll probably be as acclimatized as she's going to get, and her exertion tolerance will still be lower than it was at sea level in dath ilan – she might still want extra O2 when she's wearing her armor to do something super intense – but she should be able to handle, like, walking around and carrying objects up hills without getting absurdly winded. 

At least she's not accumulating too much delayed onset muscle soreness. The long enforced rest period helps a bunch; she woke up kind of stiff in the middle of the night and did a bunch of gentle static stretches during the Nothing Else To Do, and now she's fine. 

...Ohhhh right also this planet has 1.2G gravity. It's a small enough difference that Merrin has now completely stopped noticing it consciously, but yeah, pushups will be more tiring if she's suddenly "gained" 20% of her body weight. 

She puts her suit on and goes out into the chill morning air to set up the solar panels in her new location. 

She'll set it up beside the top of the archway. It's occurring to her that the best place to keep her main battery storage might be buried in a pit beside the solar panel unit; temperature extremes are bad for it and will degrade it over time, and the temperature a meter down will vary even less than the temperature "indoors". 

She has three meters of cable for it, plus a bunch more attached to various devices, not all of which she's ever going to need here, and she does in theory know how to splice cables together. She can create a permanent "power station" and run the cable directly into the cave to charge her suit.  

...That's a ton of digging and it's not a right-now project, she's just thinking ahead. There's so much thinking ahead to do. 

Aaaand time to go back into her cave and make a TODO LIST.

Somehow Merrin has not at any point managed to actually do that? It feels like she's spent the last three days prioritizing solely off "what does she need to do right now to avoid dying in the next 64 hours" and all of a sudden she's...not...especially at risk of dying at that timescale? She totally could spend a bunch of the day resting in her sleeping capsule, breathing ambient air, and finish the day with more stored power than she started out with. 

Saving her electrical power is not her highest priority anymore. If it's headed toward spring, then the days are going to get longer...and longer...and longer...and eventually she's probably going to be getting more solar power production than she can use or store. 

The things most likely to kill her, at this point, come down to:

1) Stupid accidents. 

2) Surprise hazards that she failed to predict in advance and was unprepared for. 

3) RUNNING OUT OF FOOD. 

4) SUMMER.