Moho's Secrets Revealed

[Samio]

The Mohoian Pits

This is an image of the northern pit.

Since Moho has become a part of the Kerbin system, (Or canonically discovered by squinting at the sun) many that have ventured to this scorching world have pondered about the two mysterious pits located at the poles of this planet. Vast and seemingly bottomless, those that took risks would venture down to the bottom only to find it closing shut to the point where one would get stuck before even reaching the bottom.

To spare those incapable or unwilling to properly examine and understand these anomalies, I had taken upon myself to finally answer the question of whether or not these pits really are bottomless, and if not how deep down they go.

The Probes

To accurately determine the depth of the pit, I used a mixture of two kinds of probes, one to determine the width of the pit, and another to reach as close to the bottom as possible and relay a signal back so that I can use its position to measure distance.

The Measurement Probe

I designed this probe only to function as a measuring tool, all it would do is land as close as possible to the rim of the pit and indicate its distance to any nearby probes.

It has only the basics, with of course Mechjeb attached to ensure maximum accuracy when landing and measuring. I used two of them during the mission, one on each side of the pit.

The Decent Probes

This set of probes were the ones I used to find and land on the bottom of the pit. The First and largest probe was designed to descend most of the way down until it was stopped by the closing walls. It would then drop a smaller probe that was RCS powered to make the final decent to the bottom. I figured that to reach down as close to the bottom as possible, I would need the smallest probe possible to make it to the bottom intact yet still able to register a signal back to use for measurement.

The Plan

Both pits are roughly conical in shape. To mathematically measure the depth of them, I needed to know the width of the cone at the "base", and the length of the cone along its "sides". To do this, I would place a probe at Point A, and Point B on the diagram below.

The distance between them I would then determine to be value A, which by dividing by two would give me the value needed for the top of right triangle required for the Pythagorean theorem that I would use to measure the depth.

The second probe would then descend into the pit to point C, where it would then give me the value needed for side C, the second necessary value I needed to use the Pythagorean theorem. The final depth would then be determined as side B, thereby giving me the most accurate depth I can muster with the tools I had available.

The Mission

I first launched an extra-planetary launch pad to Moho, as launching a separate rocket for each probe would be incredibly wasteful of both resources and time, and designing a rocket that could carry them all was beyond my designing skills. After landing nearby the pit, I deployed my launch pad and with the rocketparts I stored aboard it, built the three probes beside the pit. The area around the northern pit I found was extremely uneven and finding a landing spot for the two measurement probes was quite tricky as I needed a spot that had another flatish landing spot on the opposite side so I would get the best possible horizontal length with minimal vertical interference. I eventually found two spots and landed the probes accordingly.

The hardest part was the Decent Probe stage, I had to maintain a smooth decent down while avoiding the sides of the pit.

At first it wasn't too hard, the walls were a kilometer away from me and didn't really get much closer till around 3km down. Then the walls got close enough that I needed to maneuver away from them while descending and keeping the probe centered on the pit. Since the camera works by orientating itself with the poles, my camera constantly flipped about and confused the living crap out of me. Sadly this eventually caused me to overcompensate a maneuver and I slammed myself right into the walls, destroying my reaction wheel and upper half of the first probe. The rest, including the fuel tank and engines were still intact and thanks to the Mechjeb addon on the second probe, I could still control my craft. Since the reaction wheel was gone and the RCS vents were only on the second probe, I used the now flat top of the first probe to stick to the walls with enough thrust to stop the craft from flipping, but just enough that it would slowly slide down. I eventually reached as close to the bottom as I could get with the first probe and released the second one for the final decent. It reached the bottom mostly intact, and not too far down from the first probe. It was then that the mission was a success as now I had the value needed for the C side of the triangle.

The Evaluation

Thanks to the efforts of those three unmanned probes, I could now calculate the final depth of Moho's Northern Pit to within 100 meters of accuracy. Since the two measurement probes were not on the exact rims of the cone, the measurements given by them were different by at least 75 meters of the actual value, and since KSP's target finding system at more than a km is only accurate to one decimal place, I used two rough values to get an approximate answer of the actual depth.

By the values that resulted by the equations above, my final conclusion to the depth of the northern Mohoian pit was approximately 4600m deep plus or minus 50 meters.

Hopefully this mission will help future explorers and scientists uncover more about this baked world. If any data presented here contradicts itself or if I did any calculations wrong, please let me know and I will fix it as soon as I am able. Since the probes will be there indefinitely, more accurate measurements could be made in future should a mod become available that will allow me to do this without added parts.

I hope this mission has inspired future explorers to further examine the many mysteries of the Kerbol System and has finally answered the long standing questions about the Northern Mohoian pit.

Edited August 29, 2013 by Samio

[M4ck]

Shame about crashing into the wall, but it was a good mission anyways. By the way, you could've just landed one on top, drop something else inside and have look at the altimeter for both probes...

[DarthJazno]

Excellent report! I was excited to read in KSP weekly about the science experiments coming. It's pretty clear we can do quite a few experiments if we just use some imagination or actually apply some high school geometry!

[Devo]

I actually learnt something from this, nice work!

[Samio]

Shame about crashing into the wall, but it was a good mission anyways. By the way, you could've just landed one on top, drop something else inside and have look at the altimeter for both probes...

How do you exactly land on top of a giant pit?

If you mean hover above it, KSP only loads objects less than 2 km away. Even though the object would still register on the target screen, the thrusters would no longer work since it is no longer loaded so it would then descend until it reloaded and then give me an inaccurate reading.

[xZise]

This measurement was taken at the northern pole pit?

Fabian

PS: I love how you could do science in KSP. Nice work!

[Samio]

This measurement was taken at the northern pole pit?

Fabian

PS: I love how you could do science in KSP. Nice work!

Thanks, I'm planning to do one on the southern one as well, although I imagine it to be roughly the same.

Edited August 29, 2013 by Samio

[Geschosskopf]

Great job! Thanks for this invaluable contribution to Kerbal science. Surely you have saved numerous Kerbals from an unpleasant death. The only way I could think of to measure the depth of the hole was to kick Kerbals over the edge and time how long it took them to hit bottom .

Given the variable altitude of the terrain around the rim, any depth measurement will depend on where you measure from. So to continue this experiment, you might want to drive a rover around the rim noting the terrain altitude as you go. Then determine the average altitude and use that to get an average depth.

[Haze-Zero]

For Science!

[UH60guy]

Shame about the descent crash, but hey, you still got the results, right? Nice work.

Have you tried pressing "v" until you're on chase view camera for the descent? That should lock the camera to the probe orientation- so long as MechJeb or SAS can keep it upright, that may make it easier to control the lateral drift.

Another thought- what about an intentionally uncrontrolled descent? A "roller" probe? Something like a probe core inside a ball that can take some impact, and just needs a shove over the edge. Obviously I'm armchair quarterbacking ideas when I've never even reached Moho in the first place, but just some thoughts. Way to go though for actualy using science to discover things in the game.

[astropapi1]

Now try this on the Mun!

BTW, if you use mechjeb's tools, you could set a probe to hover on the edge of the crater and measure the radar altitude, and the land manually (for the glory of satan of course) on the bottom. Then it's a matter of substracting both numbers.

If you want to have more accurate distance measurements between probes, (iirc) une of mechjeb's functions show you distance to target.

Awesome job on actually doing some science on KSP.

[burkinator]

Great job, bro! But M4ck had a good point.

How do you exactly land on top of a giant pit?

If you mean hover above it, KSP only loads objects less than 2 km away. Even though the object would still register on the target screen, the thrusters would no longer work since it is no longer loaded so it would then descend until it reloaded and then give me an inaccurate reading.

I think he meant the probes on the cliffs next to the pit.

Nonetheless, I applaud your math!

[Lohan2008]

Professor Frink would be so proud... m-heyven !!

[RocketPilot573]

Nice job! Moho can finally be claimed for Kerbal-kind! Now I just have to figure out how to get there...

[JiWint]

Pythagor rocks!

[The Jedi Master]

{insert awesome clapping gif}

Well done, good sir. I have bad luck with Moho, so I haven't been able to really do anything on it.

[Atherius]

[Kinglet]

Do muns South Pole pyramid next!

(It is odd terrain, not a object).

[KerbalKore]

I don't see any power source on the measurement probe how did you power the OKTO2?

 

[Ultimate Steve]

@Bill the Kerbal Welcome to the forums! It looks like the power came from an RTG hidden away somewhere. Also, this thread is old, it is from 2013. Generally we try to avoid posting in old threads. It's called "necroposting" and it is frowned upon, but you are new here. Welcome to the wonderful world of the forum!