A Mercurial Circumnavigation

I got a little time to play this morning. Still not done, but moving along.

I came to a stunning, sudden realization that FDev has mildly interfered with my plans! That is, "tidally locked" doesn't necessarily mean tidally locked. I'm shocked and appalled. Shocked I say! ;) :D

It appears that the planet does still slightly rotate its orientation to the sun. This explains a lot, since I always seemed to hit various solar milestones sooner than expected. It became a lot more obvious as I was reaching the point that the sun was appearing behind the horizon. The planet's orbit has effectively zero eccentricity, so whatever visible libration there is should come entirely from the axial tilt, which is less than 8 degrees.

When I logged out, the sun was still below the horizon, but after about 10 hours it was poking above:






When I first landed a week ago, the star was pretty well centered on the zero elevation, as per this screenshot:



However now I've reached that point with 50 degrees to go, so it looks like the planet rotated an extra 50 degrees over the course of a week:

 
* I'm getting better at keeping my speed up without spinning out so often. Fewer unplanned stops.
I really need to work on this, although I haven't really had many opportunities to crank the throttle.
Yeah, it's really going to depend a lot on the terrain, gravity, amount of practice, etc. But I'm also finding that learning to recover from the spins helps too. Most of my spins seem to want to point me 180 degrees away from where I was going, so I've started reversing throttle to continue the spin into a full 360. Sometimes it just takes a small throttle reduction, or turning into the spin, or both. About 15 seconds or so into this video clip, I do this:

[video=youtube;E3QrobNwvvo]https://www.youtube.com/watch?v=E3QrobNwvvo[/video]
 
Alright, I've come full circle, and parked right back where I started! I found the same little patch of land, where I landed the ship when I arrived.

EDIT: I'll post the final science history entry soon.

According to exploration stats in-game:

Distance: 1.45 MM
Duration: 33 hours, 52 minutes

I'm finding that duration difficult to believe, as I would have guessed 20-25 hours, but I'm probably wrong. ;)

Start/Finish stats:



Start/Finish location screenshots:





Another one of these spots with debris and escape pods, but no visible wreckage:



And only one actual wreckage during this leg:


Along this leg, I also came across a canyon that looked impressive at first, but really wasn't that large. The shadows just made it look bigger than it was. I nearly flew off the ledge, but spotted it just in time... but considering the size, I'd have been fine to just zip down and up again. Still, I made a quick recording of it. The music is just some E-Mantra that happened to come up in the playlist while I was driving.

[video=youtube;mTLxNl4OFuU]https://www.youtube.com/watch?v=mTLxNl4OFuU[/video]
 
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Precession of Perihelion of Mercury, and Einstein

Newton's laws of motion and universal gravitation stood relatively unchallenged as the best theory of gravity for over two centuries. However, during the latter part of this period, a problem was noticed.

Due to interactions between the planets, their orbits can precess over time (rotation of orientation of the orbit). Newton's laws described this very well, for the most part. However, in 1859 Urbain Le Verrier discovered that the rate of precession for the planet Mercury disagreed with the predictions from Newton's theory. This anomalous precession lacked a good explanation for decades. Though many ideas were suggested, they all failed to hold up to scrutiny.

Part of the problem is that Newton's theory depended on the assumption that mass, distance, and time are constant regardless of where you observe them.

Albert Einstein published his theories of Special Relativity in 1905 and General Relativity in 1915, which proposed a deeper underlying reality in which time, space, and mass are much more fluid, and depend on the frame of reference in which you measure them. Newton's theory is still mostly true within a single frame of reference, and on small scales and at low speeds where the differences from Einstein's system are negligible. However objects in orbit have independent reference frames, and Mercury is in a particularly fast orbit, deep within the sun's gravity well.

This new theory described a system in which space and time (together referred to as spacetime) can be distorted by the presence of matter and energy. Time is flexible, and runs slower in places that are deeper within gravitational fields. With the curvature of spacetime mediating the gravitation between the sun and Mercury, whose orbit is very close, the remaining anomalous precession could now be easily explained.

Einstein was aware of this problem in astronomy, and in his paper he proposed three separate tests that could be performed to prove his theory, and included Mercury's precession as one of them. In fact, it was soon demonstrated that his theory's predictions matched very closely with observed measurements, which cemented General Relativity as something to be taken seriously, and it remains the currently accepted theory of gravity.

It should be noted that only at extreme speeds or scales will Einstein's relativistic effects be noticed. Even with Mercury's orbit, the effects were subtle, and required precise measurements to be detectable. Newton's and Kepler's mathematical models work so well within the scale of the solar system that they are still used to launch satellites and other spacecraft to destinations throughout, and predict their motion. For this reason Einstein's theories often are not seen as a replacement, but rather a more complete realization of the same physical laws.

And this brings us full circle, to why I wanted to use a Mercury-like planet in a tight, fast orbit for my circumnavigation! ;) :D

This of course was a very superficial historical look at the development of an understanding of gravity and planetary orbits. If you're interested in more detail, there's certainly a wealth of information online about these subjects. We've only just scratched the surface, of course.






 
What, I'm still on my way!

I knew my little Cobra III would be too slow.

Oh well, maybe next time.

Congratulations on the successfull circumnavigation.

o7
 
Congratulations Orvidius, a terrific and really educational circumnavigation. I'll update my forum thread with the details and sort out the EDSM badge for you later on!
 
What, I'm still on my way!

I knew my little Cobra III would be too slow.

Oh well, maybe next time.

Congratulations on the successfull circumnavigation.

o7
Oh man, sorry about that! This little project accelerated along more than I thought. I figured I'd be out there for a couple of weeks at least.

Congratulations Orvidius, a terrific and really educational circumnavigation. I'll update my forum thread with the details and sort out the EDSM badge for you later on!
Awesome, thanks! :D
 
Thanks everyone! Now I need to decide what to do next. Right now I'm back to jonking around the galaxy while waiting for the Q4 update, which seems like the thing to do since that style of hunting for cool systems might go extinct. ;)
 
Thanks everyone! Now I need to decide what to do next. Right now I'm back to jonking around the galaxy while waiting for the Q4 update, which seems like the thing to do since that style of hunting for cool systems might go extinct. ;)
I'm still surveying this planet to find the volcanism :D Part of me really wants to stop, but another part want to accomplish the goal I set...
 
I'm still surveying this planet to find the volcanism :D Part of me really wants to stop, but another part want to accomplish the goal I set...
Yeah, I totally get that. I only did a brief look-around for it after I completed the circumnavigation. I didn't see anything quickly, and decided I probably wouldn't find any even if I put 10 hours more into it.

I'm now excruciatingly close to hitting 2 million lightyears, so there's that too. :D
 
Knowing that the planet is slowly rotating relative to the sun, I swung back over to see if my "Olympus Mons" mountain was on the daylight side yet (without remembering what the coordinates were until I arrived and needed to actually find it). Nope, totally still dark. In fact, I think it's darker now.

What surprised me is that I was able to easily land at the summit. Using the ship's altimeter, I could see that it was a measly 1.5 km altitude from the base of the slope. It just felt more impressive in the dark. However, since the planet is mildly potato-like, this area is at a high altitude overall, thus the drop in measurable gravity while on or near the mountain.



It's not at all like this one, on another planet, far far away, that is 3km tall from its base:





Not that it's particularly special either. ;)
 
Knowing that the planet is slowly rotating relative to the sun, I swung back over to see if my "Olympus Mons" mountain was on the daylight side yet (without remembering what the coordinates were until I arrived and needed to actually find it). Nope, totally still dark. In fact, I think it's darker now.

What amazed me is that I was able to actually land at the summit. Using the ship's altimeter, I could see that it was a measly 1.5 km altitude from the base of the slope. It just felt more impressive in the dark. However, since the planet is mildly potato-like, this area is at a high altitude overall, thus the drop in measurable gravity while on or near the mountain.



It's not at all like this one, on another planet, far far away, that is 3km tall from its base:





Not that it's particularly special either. ;)
I imagine I have flown over this in my search for volcanics. There are quite a few neat, but subtle features on this planet that are off the equator. Unfortunately, I think my search will end this evening with only about 60% of the planet surveyed as I am just about out of fuel in my ship.
 
I imagine I have flown over this in my search for volcanics. There are quite a few neat, but subtle features on this planet that are off the equator. Unfortunately, I think my search will end this evening with only about 60% of the planet surveyed as I am just about out of fuel in my ship.
Yeah, you gave it a good try. I'm not convinced that there's anything to find. I may come back again after the new exploration changes and see if the probe-mapping turns anything up.

The subtle details on this planet are interesting, I agree. After driving through it, I was surprised how varied the terrain could be for a planet with only a few small mountains, rarely any canyons, and sparsely placed craters. This is making me realize that I probably just don't notice these details on most other planets too. I'll have to spend more time on the ground, or flying low, in the future.
 
Hmm, I was just thinking last night (while stuck up a mountain) that it would be nice to have more tools in the SRV - an altimeter, for sure; a trip odometer would be nice, too. I had also decided to overfly my route when I complete the circumnavigation to get an overview of some of the more troublesome features - the mountain range that's giving me a lot of grief at the moment is literally invisible on the System Map image.
 
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