Submit questions for testing in KSP!

[Ben 9072]

Hey everyone,

I'm looking for some scientifically testable questions I can run a mission to answer in KSP. They can be anything - for example, the last one I did was figuring out an estimate of the density of Kerbin's oceans. I will assume realistic physics in all calculations I do, and post the mission, along with all calculations, in my mission thread, along with credit for suggesting the question to your username, and, if you would like, a link to check out a thread of yours.

The questions can be anything, but they have to follow these guidelines:

• Must be scientifically testable without unreasonable levels of speculation. (Not: "What is Minmus made out of?")
  
• Can't use known glitches in the game as "physics". (Not: "Why do planets disappear if you collide with them fast enough?" - Note that you can still question strange physics that is conceivably realistic, such as metal blocks floating on water, but not things that are obviously glitches.)
  
• The question can't require having a certain mod. (It's fine if you noticed something that caught your attention while using a mod, but it can't obviously be dependent on that mod. For example, don't ask: "Whydoes the Griffon XX in KW rocketry overheat so faster than the mainsail engine?")
  
• Nothing that relies on calculations that are obviously too complex to be reliably analyzed. (Not: "In this *500 part ship*, why does Part A always fall off before Part B?")
  

If I find one that piques my interest or one that I can think up a good method for solving, I'll use it! Thanks!

[Ben 9072]

Bumping for science!

[PakledHostage]

I posted a thread a few months ago detailing how I tried to calculate the size of the Kerbol system by observing a transit of Eve. The thread was destroyed when the forum database was corrupted in April, but I've included a link below to an album of screen shots. My result was about 30% larger than the actual value, but I am not sure if that was due to a math error on my part or some quirk of Unity's 3D rendering.

Maybe someone who's keen would like to take it on to compare results? I can dig up my actual calculations.

If that is too much effort, then another idea is to calculate the mass and size of a celestial object by placing a spacecraft in orbit around it.

Javascript is disabled. View full album

Edited August 7, 2013 by PakledHostage

[Mr Shifty]

That is awesome Pakled. Interesting that Horrocks's 1639 estimate of the AU was also off by around 30% (though he calculated 30% smaller rather than larger). I wouldn't mind seeing those calculations. How often does Eve transit? How about Moho?

[Ben 9072]

I posted a thread a few months ago detailing how I tried to calculate the size of the Kerbol system by observing a transit of Eve. The thread was destroyed when the forum database was corrupted in April, but I've included a link below to an album of screen shots. My result was about 30% larger than the actual value, but I am not sure if that was due to a math error on my part or some quirk of Unity's 3D rendering.

Maybe someone who's keen would like to take it on to compare results? I can dig up my actual calculations.

If that is too much effort, then another idea is to calculate the mass and size of a celestial object by placing a spacecraft in orbit around it.

Javascript is disabled. View full album

That's really a pretty neat way to calculate the systems' size - I might try and think up some other way to go about doing that. I'd be interested in seeing your calculations.

[PakledHostage]

I used the method that Edmund Halley proposed in 1716. It works by timing the passage of Eve across Kerbol's disk from two locations on Kerbin. A bit of trigonometry is then all that's required to calculate the Kerbal AU. I found the image below to illustrate how it works:

The difficult part is accurately determining the lengths of the transits. As shown in the images that I posted above, Eve transits Kerbol starting late in the day on UT = 162 days. I never bothered to figure out how often it transits, because I only needed one transit for my experiment.

I will dig up my calculations and post them, but it might take a few days. I have it on my computer at home, but I plan to be playing outside for the next few days rather than sitting in front of a computer...

Edited August 7, 2013 by PakledHostage

[PakledHostage]

I will dig up my calculations and post them, but it might take a few days.

As promised, here are the calculations. There aren't much in the way of comments in the calculations because they weren't meant to be presentable. The result of 19.6 million km is about 40% bigger than the actual value. The calculation depends on an accurate measurement of the transit time at the northern and southern observatory, as well as on an accurate measurement of the diameter of the angular size of Kerbol's disk as seen from Kerbin.

One encouraging thing about the calculations is that they predict that Eve crosses Kerbol's disk at an angle of 5 degrees. That is consistent with measurements. It also predicts that Eve transits about 40% of the way between the centre of Kerbol's disk and the edge. That too is consistent with measurements.

There may well be a mistake in the calculations, so feel free to point it out if you find one. Be aware that some of the values that I calculated on the spreadsheet weren't actually used for anything, however.