When we last left our intrepid explorers, Aldner and Nelemy had successfully (more or less) landed all their equipment on Tylo and were ready to start exploring. Keep in mind that the surface of Tylo turned out to not entirely resemble the maps currently posted on kerbalmaps.com (or the old maps made by Jebediah Kerman during his orbiting of Tylo many years ago, as the kerbals may have it). Some have said that the surface of Tylo is boring, but it's not a place a lot of people have explored in detail...so let's see what we find.
Aldner: "Aldner to Laythe Base. Is Hellou there?"
Hellou: "I'm here, Aldner. What's up?"
Aldner: "Nelemy and I have the Fido packed full of supplies and equipment, so we're ready to start rock hunting for you. Any particular place you want us to go?"
Hellou: "I assume you've gotten samples from the immediate area of the lander?"
Aldner: "Um...hold on..."
Aldner: "...sure! Of course we have."
Hellou: "OK...What kind of rock did you just pick up?"
Aldner: "Mmm...light colored. Lighter than the underlying rock. No stratification. No crystals."
Hellou: "Crystal structure visible using the magnifier?"
Aldner: "Umm.........no. No crystals. But not glassy."
Hellou: "So, microscopic crystals. Which tells you what?"
Aldner: "Umm...The rock cooled rapidly. Probably...extrusive volcanic rock. From the light color, maybe...rhyolite? A piece blasted to this location from by some meteorite impact?"
Hellou: "Aldner! You did listen to my lessons! I'm impressed."
Hellou: "Northeast of your location is a moderate-sized crater. I'd like you boys to start sampling there, from outside the crater, on its rim, and down inside, please."
Aldner: "Roger. We're on our way."
As expected, the rover handled well in Tylo's 0.8 g surface gravity. The eight RoveMax Model 1 wheels are not as grippy as the newer TR-2L Ruggedized Wheels, so the rover can't just barrel straight up steep hills, but I also find that they are less prone to suddenly snagging the surface and jerking the rover about. I've had a lot of experience driving with these wheels on many planets and moons, so I know what to expect.
Along the flats, the Fido can cruise along a 20-something m/s. The place where care is needed is on the downslopes where the rover can easily pick up enough speed to blow the tires, so the brakes must be applied. Also, the rover 'jitters' around on the downslopes, and this jitter can become too violent at high physical time warp factors. But the Fido can generally be driven along a 2x time warp, or even 3x time warp, if very careful. I followed my standard rover driving rules (discussed in previous episodes).
Nelemy: "Dude, why are we slowing down?"
Aldner: "Kerbol is eclipsed by Jool. I can run on just RTG power, but that stalls out on the inclines. So I'm taking a break."
Nelemy: "OK! Snack time!"
Aldner: "What, you haven't been eating snacks already back there?"
Nelemy: "Well...some. But snacks are better during official snack time!"
[Strangely, even though the sun was eclipsed by Jool, I could see it shining through Jool. But the photovoltaic cells could not see it.]
Aldner: "We've reached the crater rim. Elevation is almost 3,000 meters. It looks like it will be easy to drive down inside; the slope is not bad at all."
Hellou: "Sounds good. Any large boulders?"
Aldner: "Yes. Several. You want samples from them?"
Hellou: "Yes, please."
Aldner: "This is a darker rock. Crystals are easily visible by eye. Using the magnifier, some of the crystals are clear, some pink, some darker. All similar in size. I suppose the pink stuff is feldspar, and this is apparently a big piece of granite."
Hellou: "Excellent. See if you can break off a piece for me."
The bottom of the crater was at an elevation of about 1,264 meters. It's sometimes tricky to find the low point in a crater. An area further away that LOOKS lower may well turn out to be higher once you go there and measure it. With the rover stopped, you can use 4x physical time warp to cause the rover to slide downhill in order to help find the low point.
Aldner: "OK, Hellou. What now?"
Hellou: "I'd like you to get samples from areas that are particularly light or dark in the orbital photos. There is an area of dark land another 25 kilometers northeast of you that you can sample."
Aldner: "The dark lands? Do you want us to name it Mordor?"
Hellou: "Well! You actually did read that book I loaned to you? I'm surprised."
Aldner: "Hey, I like to read books. Even goofy ones with those elves of yours. Besides, I figured if you bothered to bring along an actual PRINT book in your personal effects, it must be good. Besides, I needed something to kill the boredom during all that landing simulator practice."
Hellou: "Well, I'm glad it was useful. I was meaning to ask...where did you put it? I'm getting things packed up for our departure, and I can't find it."
Aldner: "Nelemy's reading it now."
Hellou: "What?? You took my book with you to Tylo??"
Nelemy: "Sorry, Hellou-dude. I started reading it after Aldner, and I didn't know it was yours. Sorry."
Aldner: "We'll take good care of it and bring it back to you. Besides...just think what all your geek friends are going to think when you have the only copy of that book that has been to Vall, Laythe, and TYLO. They'll wet themselves in envy."
Nelemy: "And just think of how much you could sell it for on kBay, Dude!"
Hellou: "I'm not going to auction off that book! And you'd BETTER make sure to bring it back to me."
Nelemy: "Dude, I promise!"
The north rim of the crater was somewhat higher than the south rim. As always, it's necessary to be careful driving downslope, but the north slope outside the crater was not bad.
Aldner: "Aldner to Laythe Base. We have crossed the border into Mordor. We can zip down to the center of the area in a about twenty minutes and get some samples from there."
Hellou: "Fool. One does not simply drive into Mordor. I want to you to stop and take surface samples every half kilometer. Find any particularly dark rocks. Take pictures of them in situ, and be sure to catalog them correctly! And no putting snacks in the sample bags."
Aldner: "Roger. Tylo out."
Nelemy: "Dude...and we thought Thompbles was bossy."
Aldner: "Instead of a dark Thompbles, we have a Queen of Geology. Not dark, but beautiful and terrible as the morn! Treacherous as the seas! Stronger than the foundations of Kerbin! All shall love her and despair."
Nelemy: "Um... What, Dude?"
Aldner: "Aren't you at Rivendell yet?"
Nelemy: "Dude, I'm just getting there. Say...we should name our Fido 'The Prancing Pony'."
Aldner: "You can name YOUR Fido 'The Prancing Pony'... I shall name mine 'Shadowfax.'"
Nelemy: "Shadow what?"
Aldner: "Keep reading."
Below, the perilous crossing of Mordor. Only without much peril. It was a pretty comfortable ride, actually. But a dark land, forsooth.
Aldner: "Aldner to Laythe Base. We've crossed most of Mordor and did the requested sampling. What would you like next? I can see a lonely mountain peak in the distance to the northeast that's lighter in color. Do you want us to explore that?"
Hellou: "Lonely Mountain? What other books have you been reading?"
Aldner: "Books? No other books. But the visual downlink from the orbiting station shows some mountains to the northeast, even though Jeb's maps don't show anything. One peak is by itself...it looks like we could drive up it."
Hellou: "OK. Yes...mountain samples would be great."
Below, Aldner and Nelemy headed further northeast toward Lonely Mountain. It was about this time that I was getting a bit tired of driving that day, and started experimenting with MechJeb's Rover Autopilot feature... But, again, it was a disappointment. At least for my rover design, the autopilot's speed control function is not very useful. When the rover is coming downhill, the autopilot does not use the brakes to keep the rover from exceeding the set speed (even though the brakes can easily handle this), so the rover ends up going at unsafe speeds if left to the rover autopilot. I suppose that a rover with the newer stickier tires would work better, since simply controlling the throttle might slow those rovers down OK. Also, when the rover reaches an upslope where the older, non-sticky wheels don't have enough grip to keep going straight uphill, I have to take manual control anyway to start tacking left and right as needed to maintain headway. So: Rover Autopilot...not very useful.
Aldner and Nelemy were able to follow a ridge up toward the peak of Lonely Mountain. The west side of the mountain was very steep (way too steep for the Fido), and the south slope was also fairly steep (which would have required a lot of switchback driving), so Aldner swung wide to the east where the slope was shallower.
Below, a wider-angle view of Lonely Mountain from the south ridge.
Aldner: "Aldner to Laythe Base. We have reached the summit of Lonely Mountain."
Kurt: "I copy you, Aldner. Hellou is asleep, and I'm monitoring the radio during the night shift."
Aldner: "Ah...yeah. The days here on Tylo are four times longer than those long days we get on Laythe. And I was finally getting used to those. My sense of time is all messed up relative to you guys."
Kurt: "Indeed. "
Aldner: "I guess we'll camp here for a while until I find out what Hellou wants us to do next. There are some larger mountains to the northeast, but I'm not sure they are drivable."
Below, the map view shows the location of Lonely Mountain.
Here is an animated zoom-out showing the shape of Lonely Mountain.
Nelemy: "Dude, do you think we could drive down the west face? The slope that direction doesn't look terrible."
Aldner: "Not a chance. You're only seeing the top of that slope from here. Do you see where the ground suddenly ends a ways off there? That's where the serious slope starts. Now, if we were on Laythe and had a BirdDog, it would be fun to run down that slope and take off when we reached takeoff speed."
Nelemy: "We need to order some air for Tylo, Dude. So what direction will we go?"
Aldner: "I'm continuing north. The slope of the north face is doable."
Below, the run down the north slope required constantly pressing on the brakes, and even some occasional backpedaling with the reverse key, to keep the speed under 50 m/s. But the boys seemed to enjoy it a lot.
Below, the view back toward Lonely Mountain from the northeast.
Aldner and Nelemy then headed toward the larger mountain range to the northeast. The driving here involved more up-and-down slope, and the speed got a bit too high on a couple of the downslopes, so some blown tires needed to be repaired.
Hellou: "Laythe Base to Shadowfax. How are you guys doing?"
Aldner: "Good morning, Hellou. We drove part way up the large mountain, but it was too steep, so we turned to the side."
Nelemy: "It was Caradhras, Hellou-dude! It defeated us."
Aldner: "So we're going to go down into the double crater to the west."
Aldner: "That was my thought, but Nelemy is afraid of Balrogs, so we are just calling it The Two Craters."
Hellou: "Orthanc and Minas Morgul?"
Aldner: "Were those the two it meant? I wasn't sure. Anyway, Jeb's old data shows that the craters should have a flat, smooth bottom, but from our view on the rim here, I don't think that's the case. I think his instrumentation was wacky.
Nelemy: "Sort of like Jeb himself, Dude."
Below, the arrow marks the location of the Fido overlooking The Two Craters.
Here is the view toward the Misty Mountains to the east of the Fido's location.
And below is the view back toward the south and Lonely Mountain off in the distance.
Finally, the map view of the location:
The drive down the steep slope was taken at an angle:
The Two Craters did not have a smooth, 'sea level' bottom, and only got as low as twenty-one-hundred-something meters.
Below, an overview of The Two Craters, with X marking the lowest spot found by the boys.
With Aldner and Nelemy safely down on Tylo and exploring away, Emilynn and Hellou were ready to return to Vall and finish their interrupted mission there. So Kurt and Thompbles threw them a send-off party that couldn't be beat the day before they headed back to Vall.
The next morning, Emilynn climbed on board the Ladyhawk SSTO spaceplane and fired up the systems for their flight to orbit.
Emilynn: "Shake a leg, Chickadee. We're burning daylight."
Hellou: "Coming, Emi. I'm just taking one last look around the place. Even though we didn't plan to come here at first, I'm glad we did. I'll miss this pretty little world."
Hellou climbed aboard the rear cabin of the Ladyhawk. In addition to the normal supplies and equipment (which had been packed and ready for a couple months now), she was taking along a secondary set of Laythe surface samples to return to Kerbin...just in case the main set of samples from the Laythe mission don't make it back to Kerbin due to some unforeseen circumstances.
Emilynn: "Laythe Tower...Ladyhawk is ready for flight. You boys take care of yourselves, you hear?"
Kurt: "Roger, Hawk. You take care, too. Fly safe."
Emilynn: "I surely will, Jaymack."
Hellou: "Goodbye, Kurt! Remember that we're just a radio call away if you want to talk."
Emilynn fired up the turbojet and flew the Ladyhawk off to the southeast.
Below, more pretty volumetric cloud pictures as the Ladyhawk headed southeast to the equator, then turned east and began to climb in earnest.
My flying was pretty sloppy, so I won't blame it on Emilynn. I climbed too fast too soon, and flamed-out the turbojet even at minimum throttle. Then dropped back too low as I was gaining speed. But I finally got the plane to a height and speed where a short burst of the rocket engines pushed the apoapsis up to 116 km, and it didn't decrease too much from that as the Ladyhawk coasted out into space.
After the orbital insertion burn, the plane had 1570 m/s of delta-V left onboard. Not bad, but certainly not my best showing. The apoapsis of the Ladyhawk was left at 115 km because the ship was ahead of the Vall Ship, so it needed to slow down and let the Vall Ship catch up. With a small maneuver near apoapsis, the encounter with the Vall Ship took place near the next periapsis.
Hellou: "Emi. We're passing over Dansen Island. Could you please turn the plane so I can get a look out of my window?"
Emilynn: "Sure thing, Chickadee."
Below, Emilynn brought the Ladyhawk to a perfect rendezvous and docking with their Vall Ship, which had been patiently waiting in Laythe orbit since they hastily evacuated it in the emergency capsules after making their mad dash to Laythe.
It took a few EVAs to transfer the samples over to the Vall ship.
Emilynn: "Vall Station to Laythe Base."
Kurt: "Go ahead, Hawk."
Emilynn: "We are transferred over to the Vall Ship. All system checks look good."
Kurt: "Roger, Hawk. Would you like me to take the Ladyhawk off your hands?"
Emilynn: "Negative, Jaymack. I'd like to handle transferring her remotely to Laythe Space Station. But I'd appreciate it if you and Thompbles could get those Tugs sent over to us for some refueling."
Thompbles: "I'm already on that. The first Tug should be there in a couple hours."
Emilynn: "Thankie, Thom. I'm detaching the Ladyhawk now to send it over to the space station."
The Vall Ship and the Laythe Space Station happened to be located fairly close together in orbit, so all it took was a little boost to raise the Ladyhawk's apoapsis a bit to slow it down, and about one orbit later it was matching velocities with the Laythe Space Station under Emilynn's remote piloting. The Ladyhawk was docked to the Space Station opposite from the Raptor. Then fuel was transferred from the station's tanks to the Ladyhawk so that she would be ready for use by the next crew to arrive at Laythe.
Below, Laythe Tug GS5 (umm...I'm not even sure what payload that Tug delivered to Laythe...so many ships to keep track of) still had more fuel than it needed to return to Kerbin, so Thompbles sent it to rendezvous and dock with the Vall ship. Some of the Tug's fuel was transferred to the Vall ship, and some fuel left in the Tug would be used to boost the combined ships out of Laythe orbit.
Similarly, Laythe SP Tug A was also sent to dock with the Vall ship. It also had more fuel than needed to return to Kerbin, so some of that fuel would be used to boost the Vall Expedition ship back to Vall.
Below, you can see the Hohmann transfer orbit that I set up to send the Vall Ship (with extra attached Tugs) off to Vall, requiring about 605 m/s of delta-V.
The next figure shows the ejection path from Laythe, and the arrival path at Vall.
For the burn to Vall, only the nuclear engines on the extra two Tugs were used. The nuclear engines on the Vall ship were disabled for this burn so that no fuel would be used from the Vall ship's Tug.
Below, Emilynn and Hellou's ship leaves Laythe, with Vall and Tylo visible in the background.
Note! You must be very careful when doing Hohmann transfers between the moons of Jool (as I found out before when sending off Tugs to temporary parking orbits out between the moons). It's tricky to get the ship sent on its way with enough speed to escape, but not so much speed that you overshoot the target moon's orbit (because Jool's large moons are quite close together and have large SOIs). After the ship leaves Laythe's sphere of influence, heading out into its slower orbit, it can end up re-encountering Laythe's SOI. This happened to the Vall Ship...but when I slowly advanced the time, the ship made it back out of Laythe's SOI with its trajectory intact.
BUT... if you go barreling through these SOI changes at even moderate time warp factors, the ship could end up in a very different orbit (or could collide with Laythe). So it's vital to step through these SOI changes at 1X time warp.
You could expend some extra delta-V to boost the ship away faster (not in a perfect Hohmann trajectory), and that would make it less likely that the ship would run into this problem.
Below: As the Vall Ship approached Vall, the extra Tugs were separated. The Vall ship would be braking into Vall orbit, while the extra Tugs would whip past the planet to be placed in a parking orbit out between Vall and Tylo (where they would wait until the next transfer window opens to send them back to Kerbin for re-use). I had to do a burn by the Tugs once they were beyond Vall in order to keep them from re-encountering Vall's SOI, and then later I circularized their orbit between Vall and Tylo.
The Vall capture maneuver is shown below. The ships were targeted to pass within 10 km of Vall. A burn of 46.7 m/s would brake the Vall ship into an orbit with 1,000 km apoapsis. The extra Tugs would pass Vall and escape (although their trajectory shows up as a complete ellipse here, rather than showing their escape point).
The Vall Ship's capture burn was in the dark, so I have no pretty pictures. After the capture burn, when the Vall Ship swung out to its 1,000 km apoapsis, a 42 m/s burn was done to raise its periapsis to the 167-km altitude of the Vall Lander's orbit. Then shortly after than, a plane shift burn of 2.6 m/s was made to match planes with the Vall Lander. And it so happened that a small 11 m/s burn was all it then took to target the Vall Ship for an intercept with the Vall Lander. Finally, a burn of 171 m/s was needed at closest approach to bring the ships to rendezvous.
Below: The view from the Vall Lander of the Vall Ship braking for rendezvous (with its nuclear exhausts pointing at the Lander).
Finally, Emilynn brought the Vall Ship and the Vall Lander together for a perfect docking.
Emilynn: "Annnd...we are docked!"
Hellou: "OK! I'm going to EVA over and see if all the samples in the freezers are OK."
Emilynn: "You will NOT. You'll wait an hour for the nukes to cool down before doing the EVA."
Hellou: "But the nuclear engines are behind the shadow shields from here. That shouldn't be a problem."
Emilynn: "No. You are out of practice doing EVAs, and I don't want a sloppy maneuver to put you out into the gamma field of the nukes. Just wait. The Lander has been floating there a long time...an extra hour won't hurt."
Hellou: *sigh* "Yes, Mom. You're right. I've just been worried about all of the samples."
In the meantime, Emilynn maneuvered the "Vall Rovers" Tug over the the Vall Ship. This Tug (which had brought the two rovers to Vall) had extra fuel, and it especially had extra RCS (because I had used an RCS tank as a spacer to mount the rovers on top of this Tug). Also, the Tug happened to be well positioned, so it could be brought over to the Vall Ship using only RCS power (no need to turn on its nukes).
The extra RCS tank (and its attached Senior docking port), which was nearly expended by then, was separated from the Tug before the Tug made its final rendezvous maneuvers with the Vall Ship. (The RCS tank and docking port became space debris.) Then the Tug was docked to the rear of the Vall ship. Emilynn then shifted the orbit of the Vall Ship slightly so that it would not encounter the debris in the future.
Emilynn: "OK, Chickadee. You are clear to EVA over to the Lander and check out your ice cubes."
Hellou: "Roger. I'm off."
(And Hellou's EVA manuever was a bit sloppy, and ended up with her getting further from the ship than desired, but Emilynn did not mention this.) Emilynn was busy transferring fuel from the Vall Ship to the radial mounted tanks of the Vall Lander. Once that was complete, Emilynn buttoned down the Vall Station Ship for automated mode, and transferred over to the Vall Lander.
Emilynn: "How are your samples?"
Hellou: "Everything looks good. I'm going to transfer the samples over to the Vall Ship...since we never had a chance to do that the last time we were here."
Emilynn: "Well, we were in a bit of a hurry, as you may recall. I'll be checking out the Lander systems. Give me a holler if you need me."
Once all the transfers were made, and all the Lander systems checked out green, the girls too a break for some rest and relaxation (and to allow the sun to rise at their landing target). Then Emilynn separated the Lander for their return to Vall. They would be returning to the location of their second landing because they never completed all of the intended activities at that site. Retro fire (below) was nominal.
Landing on Vall is a piece of cake compared to landing on Tylo. I snuck a peek out Emilynn's window during the final descent, and the Fido rover was visible a little over a kilometer away.
Below, we see the Vall Lander safely down on the surface, with Jool and Laythe hanging in the background.
The next step was to remotely summon the Fido rover to make the one kilometer drive over from the original landing site to the new location of the Vall Lander.
Below, the view out of Emilynn's window as the Fido approached the Vall Lander.
Our heroines celebrated kerbalkind's return to Vall with another flag planting ceremony and a live transmission back to Kerbin. Vall Base was back in operation!
In the meanwhile, Aldner and Nelemy had not been sitting on Tylo lounging about. Well, not ALL of the time, anyway. Orbital images showed that the lands to the north of The Two Craters was lighter in color than anything they'd explored as yet, so they headed north, zigzagging up the north slope of the crater and off toward the bright lands to the north, which Nelemy named Lothlorien, having gotten that far in the book.
Lothlorien proved to have a lot of up a down driving over ridges.
Nelemy: "Nelemy calling Hellou. Nelemy calling Hellou."
Hellou: "Hi, Nelemy! What's up?"
Nelemy: "We have reached Lothlorien, and we're out to get some samples. I found some rocks that are transparent inside when I break them open. Lots of them! Maybe they're diamonds! And there's white powdered rock all around."
Hellou: "OK. What happens when you touch the tip of the hot-probe to the rocks?"
Nelemy: "Umm...hold on. Whoa, Dude! The stuff vaporizes!"
Hellou: "Congratulations, Nelemy...you've struck a fortune in ice. Put samples in the freezer compartment of the Fido hab. You may have to take out some food to make room."
Nelemy: "Nah, Dude...I've been eating all of the freezy-pop snacks first. There's plenty of room."
Because Hellou was somewhat busy on Vall, and so not available to give them detailed instructions, Aldner and Nelemy decided to just continue in a general northward direction through Lothlorien. They were heading toward an interesting looking pass in the distance, but the up and down driving resulted in going too fast on the downslopes a few times, and blowing a tire or two.
The pass was actually pretty steep, so they veered off to the right so that they could then sweep back and attack the ridge at a shallow angle back toward the west.
They found an interestingly-shaped white mountain off to the west of their path, but it looked too steep to drive, so they just continued heading north past it, up and down over moderately-low ridges.
There was a bit of unwelcome excitement at one point when driving down a shallow slope (and not even very fast...only twenty-something m/s) when the rover seemed to hit some mysterious snag and ended up careening along on four wheels for a bit until Aldner used the cockpit torque to slam the right wheels back down. [I'm still not sure what caused that, but I was using my joystick to control the rover at the time, so I was able to press the trigger and snap a picture in the midst of trying to control the thing.]
North of Lothlorien was a large circular dark feature that Nelemy named the Dead Marshes. Jebediah's old data indicated that the dark feature should be at low elevation, but Aldner and Nelemy found it to be at 4,000 meters. Goofy old data.
The map and overview below show the 'low' part of the Dead Marshes.
Below: Nelemy out sampling some of the rocks from the Dead Marshes.
A wide ravine lead northward out of the Dead Marshes, so Aldner and Nelemy continued in that direction.
Eventually they were going up hill over the northwest rim of the Dead Marshes, when Nelemy took a break from reading.
Nelemy: "Dude, where are we now?"
Aldner: "Mmm...let's see. About fifty degrees north latitude."
Nelemy: "Dude! Fifty degrees? Time sure does fly when you're reading a good book."
Aldner: "When SOME people are reading a good book."
Nelemy: "Dude. We're over halfway to the north pole."
Aldner: "Yes. Yes we are. Do you want to go the rest of the way?"
Nelemy: "Yeaaah. Cool."
Consulting the map in the front of the book, Nelemy named the northern lands Forodwaith. Below are some pictures from 58 degrees north latitude, with Jool getting fairly low in the sky, suitable for taking some nice pictures.
Once they got to 70 degrees north, the low angle of the sunlight made everything look pretty dark. [I've lightened up the images a little from this point forward.] Below, Kerbol was getting pretty low in the west.
So the boys decided to camp for another couple days until Kerbol rose again. Below is an image of Jool and Laythe at night (I used a kerbal on EVA to light up the Fido in the foreground with his helmet lights).
[In fact, let me explain something at this point. I'm assuming that Aldner and Nelemy would really be taking a couple weeks doing this drive, with breaks along the way for sampling, sleeping, and rest & relaxation. But, in truth, I drove this whole way up to 70 degrees north latitude during just PART of ONE Taylo daylight period. Now, Tylo daylight periods are over 30 hours long, but still, I was covering ground pretty fast (usually at 2X or 3X physical time warp). For me, this drive took four days of driving, two or three hours a day. Thank Kod for audiobooks to entertain me during the drive. Also, it helped that once they got to Forodwaith, the land had settled down to low and gently rolling terrain, so I could actually use MechJeb's rover autopilot to do most of the driving (only keeping an occasional eye on it to watch for runaway-downslope-excursions).]
At around 80 degrees north latitude, the boys started running into the problem that the low angle of the sunlight on the solar panels resulted in the Fido using energy faster than the solar panels could provide power. This dictated frequent stops to allow the batteries to recharge (less than 10 minutes of game time to recharge). There was never any danger of the Fido getting stranded in a dark valley where the sunlight could not reach, because the rover has two RTGs that can recharge the batteries in about 10 minutes. But parking on a south slope made the charging faster.
Aldner and Nelemy started seeing some strange terrain at about 88 degrees north latitude. It appeared at first that there might be a mountain at the pole...but it eventually became clear that the mountain was off to the side of the pole. But there were jagged ridge lines running radially from the polar area.
It's not unusual for planets and moons in KSP to have anomalous terrain at their poles (such as the deep "Mohole" at Moho's north pole), and apparently this is also the case for Tylo. Below is a zoomed-out overview of the polar region (the arrow marks the location of the rover, a couple kilometers from the pole). Well...this was a bit exciting.
Aldner decided that it would be beneficial to drive over to the radial ridge line so that he could drive along the sunward-facing slope of that ridge (to keep the batteries charged). But when the Fido approached the radial ridge, it ran into strange gravitational anomalies (below). You can see that despite having the forward throttle floored, and the rover actually pointing downhill alittle, the rover was only able to creep along at about 3 meters per second (also note that the battery charge is fine). And when the rover hit the areas with an up-slope, it actually SPED UP. Freaky time.
The boys persevered, and plowed northward down Anomaly Canyon, sometimes creeping along downhill at full throttle...sometimes zipping uphill at no throttle...sometimes driving along normally. It did not help matters that the lights of the rover were often ineffective in lighting up the terrain (This actually was happening further south as well...on some patches of land, the lights simply did not light up the ground. But it was particularly annoying when trying to drive in the far-north dark areas).
Eventually Aldner decided that it was safer to drive in the less-freaky areas a little ways away from the radial ridge lines, even if that necessitated occasional stops for battery recharging.
It was nice that even this close to the pole, the boys were never long out of line-of-sight communication with Laythe or Vall. Yes, they would lose line-of-sight when heading down a slope, but could pick it up again on the upslope.
Aldner: "OK... We're going to have to stop here. The terrain ahead is too steep, and it's in shadow, so I can't see what's what."
Nelemy: "Dude. So we've come this close to the pole, and we can't get there."
Aldner: "Not necessarily. Let's wait a day for the sun to move around the sky and light up things from the other direction. Meanwhile, let's get some rocks to make Hellou happy."
Half a Tylo day later, the sun was indeed illuminating the situation better.
Nelemy: "Dude, It looks like we could backtrack a ways, and then drive down into that valley right below us at an angle on the slope."
Aldner: "Yes, but that will only get us a little closer to the sharp canyon beyond. And the Fido could never handle the kind of slope in the final canyon."
Nelemy: "So we're defeated?"
Aldner: "No. I'll go down on foot."
Nelemy: "Dude! Can't we both go?"
Aldner: "No. One of us should stay with the rover to report back to Base."
Nelemy: "OK, then. I'll go down on foot."
Aldner: "Flip a coin?"
Nelemy: "Sure! Um...we don't have a coin."
Nelemy: "Nelemy calling Laythe Base. Come in, Dude."
Kurt: "I read you Nelemy. What did you guys decide to do?"
Nelemy: "We need you to pick a number for us again."
Kurt: "Ah. OK...I'm thinking of a number from one to a million. Guess."
Nelemy: "Dude, I want five-hundred thousand!"
Aldner: "I'll take five-hundred thousand and one."
Kurt: "The number was 699,492. Aldner wins."
Aldner: "OK, Little Buddy. I'm going to be out of line of sight in the deep part of that canyon, so we'll probably lose comm link. You sit tight here and give me two hours before you panic or anything."
Nelemy: "And then I'll come get you."
Aldner: "No. And then you'll hike down to the the lip of the deep canyon and see if you can regain contact, and find out what happened. It looks like that canyon runs off at a shallow angle away from us, so even if I can't climb back out, I may be able to walk out the shallow way. Then you'd have to drive around to get me."
Nelemy: "Dude, that's way on the other side of the world!"
Aldner: "...which is only a few kilometers' drive from here. Head south a couple kilometers until you are beyond the weird terrain, then circle around and find the opening of that far canyon. Easy as pie."
Nelemy: "OK. I got it."
Aldner was able to handle the initial slopes with no problem (and I could run him along a 4x physical time warp).
Aldner: "OK, Nelemy. I'm at the lip of the steep part. I can see where terrain lines are coming together. That must be the pole. But I'll certainly be out of line-of-sight."
Nelemy: "Dude! Be careful."
Aldner: "Hold on..."
Nelemy: "Dude? Dude?"
Aldner: "OK, I went a little way down the slope, and I was able to climb back up to the lip. This should be no problem. I'll talk to you in a bit."
Below: Aldner found the north pole of Tylo. It actually took less than 25 minutes of game time for him to reach it (and much less time for me, since I could run him a 4x speed). There were cracks in the terrain that ran together at that point...and he could see STARS through the cracks. OK. Every kerbal knows to NOT touch that stuff.
Aldner tried to plant a flag on the pole.....and it exploded. [And the game became unresponsive. I could still pan around, but I couldn't control Aldner or make any other game functions work. I think the game was stuck waiting for me to fill in the flag dialog box information for the exploded flag...but there was no dialog box showing. So I force-quit the game and reloaded......and Aldner was still fine by the pole. So this time I had him plant the flag NEAR the pole.]
The second attempt at planting the flag was a success.
Below is a view of the polar trench looking outward along the canyon. The pole was not at the lowest point in the canyon, because the line coming from that direction slopes upward (the lines coming from the other directions slope downwards. So, indeed, Aldner probably could walk out of that canyon to sane land in a couple hours.
But it turned out that the canyon escape route was unnecessary. Aldner was able to climb back up the steep slope of the polar trench and return to the Fido rover, much to Nelemy's relief.
Next episode: More driving, I assume. But not in as much detail unless there are other interesting things. Also, the Bop and Pol exploration ships are arriving soon to the Jool system, and those will need to be maneuvered into place.