[KGSS] Examining Kerbin's atmosphere

[Mr_Brain]

Examining Kerbin's atmosphere in a very low orbit

The KGSS needs to place a probe in an decaying orbit in Kerbin\'s atmosphere to measure temperature, atmospheric density, pressure and several other values. Your mission is to:

- attach the crxTelemetry module (or similar) to a space-capable spacecraft

- determine the exact end of Kerbin\'s atmosphere

- enter a decaying orbit there (inside the atmosphere) with the spacecraft the telemetry module is attached to

- use the telemetry module to get the values for the following: static pressure, dynamic pressure, pressure multiplier, height above ground level, height above sea level, external heat and module heat.

- activate a parachute at 700m above ground so the probe can land safely so the samples can be retrieved. Deploying the chute higher than 700m will lead to inconsistent results in measuring the lower atmosphere.

- think about the results: Is pressure related to height over ground or height over sea level? Does a hot atmosphere heat parts up?

- post what you found out.

Variations: future versions of KSP will have other planet\'s and different atmospheres

Mods: crxTelemetryMk2 Module. Other mods permissible.

Restrictions: Your parachute must not be opened above 700m above ground level.

Rewards: Fun, knowledge

Posted with permission from the KGSS

Edited August 5, 2012 by Mr_Brain

[Zephram Kerman]

We all assume air pressure in is related to height over sea level... but nobody in KSP has ever actually established this scientifically. I'm looking forward to this one!

[togfox]

Yes, similar. Will be an interesting stat to check.

[dikkjo]

Hey,

Downloaded the mod.... let's see what we can do ;-)

Always loved the KGSS!

[dikkjo]

And after a long day ;-P

So as requested, i've built a simple almost-stock rocket serving the purpose with the telemetry part directly attached under a Mk1 pod.

I figured out that it would be interesting seeing the differences between Jeb, Bob and Bill's mental state, so i organised three consecutive launches with our three beloved kerbonauts.

The first launch was serving the purpose of identifying the beginning of the atmosphere with a not too big degree of error, whereas later launches would use the method of the (very) slowly decaying orbit.

The collected raw data exceeds 7MB after 7z compression, so i guess i will not upload it here. I may upload it to mediafire or something if anyone is interested.

So the results are the following :

Methodology

Launch 1 (L1) - Orbit : Ap 153km, Pe 28km - Pilot : Jeb

Launch 2 (L2) - Orbit : Ap 70.1 km, Pe 58km - Pilot : Bill

Launch 3 (L3) - Orbit : Ap 70.1 km, Pe 60km - Pilot : Bob

Telemetry start very close to apoapsis after separating from last stage

Craft: Corax I - warning mechjeb inside!

Altitude of Kerbin's atmosphere

* Based on relevation of pressure/density

** The telemetry plugin do not record values under 1x10E-6 [

*** The values are the means between points

Measured ASL at rentry

1st Launch - Jeb : 69072.13993

2nd Launch - Bill : 69077.65728

3rd Launch Bob : 69077.69043

Measured AGL at rentry

1st Launch - Jeb : 68488.10387

2nd Launch - Bill : 68800.64062

3rd Launch - Bob : 68460.42426

Analysis and conclusions

We can see that the standard deviation of results is much bigger for AGL measurements. Considering that the first launch is also the less precise, ASL results for second and third launch are pretty consistent.

This seems to indicate that the atmosphere limit is somewhere between 69077.65725 and 69077.69043 meters, which gives a marge of 3.31 centimeters of error after only two meaningful launches.

Naturally more launches would be required to refine this measurement. ( and maybe restaging the telemetry lower )

The differences between ASL and AGL are very low on Kerbin, so it's not easy to see any significant difference indicating pressure would be related to one or the other. Anyway the consistency of measurements may indicate that pressure is indeed relative to ASL.

Crew Behaviour related to environment

here the results are deceiving, infact the values of panic and wheee factor never changes during all the trip. EVA changes the values, but replaces them with nothing at all

Jeb => Panic: 0.5, Wheee: 0.5

Bill => Panic: 0.5, Wheee: 0.8

Bob => Panic: 0.3 , Wheee: 0.1

No matter how many G's or air is around, this guys are persistent as the "brave" and "dumb" values in the...persistence file ;-P

So i'm not sure if it's a plugin issue or the game just randomize their behaviour based on these two fixed values.

Bonus Graph

A nice nerdy project :-) cheers

[dikkjo]

Since i'm limited at max 9 pictures per post, ill add some here from the mission

[Mr_Brain]

The differences between ASL and AGL are very low on Kerbin, so it's not easy to see any significant difference indicating pressure would be related to one or the other. Anyway the consistency of measurements may indicate that pressure is indeed relative to ASL.

Crew Behaviour related to environment

here the results are deceiving, infact the values of panic and wheee factor never changes during all the trip. EVA changes the values, but replaces them with nothing at all

Jeb => Panic: 0.5, Wheee: 0.5

Bill => Panic: 0.5, Wheee: 0.8

Bob => Panic: 0.3 , Wheee: 0.1

No matter how many G's or air is around, this guys are persistent as the "brave" and "dumb" values in the...persistence file ;-P

So i'm not sure if it's a plugin issue or the game just randomize their behaviour based on these two fixed values.

Bonus Graph

A nice nerdy project :-) cheers

And after a long day ;-P

So as requested, i've built a simple almost-stock rocket serving the purpose with the telemetry part directly attached under a Mk1 pod.

I figured out that it would be interesting seeing the differences between Jeb, Bob and Bill's mental state, so i organised three consecutive launches with our three beloved kerbonauts.

The first launch was serving the purpose of identifying the beginning of the atmosphere with a not too big degree of error, whereas later launches would use the method of the (very) slowly decaying orbit.

The collected raw data exceeds 7MB after 7z compression, so i guess i will not upload it here. I may upload it to mediafire or something if anyone is interested.

So the results are the following :

Methodology

Launch 1 (L1) - Orbit : Ap 153km, Pe 28km - Pilot : Jeb

Launch 2 (L2) - Orbit : Ap 70.1 km, Pe 58km - Pilot : Bill

Launch 3 (L3) - Orbit : Ap 70.1 km, Pe 60km - Pilot : Bob

Telemetry start very close to apoapsis after separating from last stage

Craft: Corax I - warning mechjeb inside!

Altitude of Kerbin's atmosphere

* Based on relevation of pressure/density

** The telemetry plugin do not record values under 1x10E-6 [

*** The values are the means between points

Measured ASL at rentry

1st Launch - Jeb : 69072.13993

2nd Launch - Bill : 69077.65728

3rd Launch Bob : 69077.69043

Measured AGL at rentry

1st Launch - Jeb : 68488.10387

2nd Launch - Bill : 68800.64062

3rd Launch - Bob : 68460.42426

Analysis and conclusions

We can see that the standard deviation of results is much bigger for AGL measurements. Considering that the first launch is also the less precise, ASL results for second and third launch are pretty consistent.

This seems to indicate that the atmosphere limit is somewhere between 69077.65725 and 69077.69043 meters, which gives a marge of 3.31 centimeters of error after only two meaningful launches.

Naturally more launches would be required to refine this measurement. ( and maybe restaging the telemetry lower )

Very good! You really helped the KGSS! With this data we will be able to calculate the weather for the next decade! If we find out what the word "weather" means, of course.

Regarding the crew stats: Yes, it just displays the dumb and brave values, I got a message regarding that, but the forum didn't save my changes to the thread for some reason. However, I don't think it's random as I already saw Bill smiling when the craft landed with about 3m/s.

[togfox]

Nice work. The low terrain height on Kerbin does make it difficult to spot differences in ASL/AGL on a graph. Not much we can do about that I guess. It's unfortunate that Jeb's "enjoyment" factor is not mapped. I wonder if that is exposed by the game at all. Maybe Corax will see this and give it some thought.

[dikkjo]

Thx guys, it was funny and also it gave me the opportunity to learn to use gnuplot.

It's unfortunate that Jeb's "enjoyment" factor is not mapped.

Yes, to be honest that bit was what gave me the motivation to do this ;-) After this I've read Corax code and it says :

// internal Kerbal representation has changed with 0.16:
// TODO: where has the wheee gone?!

I think I have an idea where to find it in the game code, i'll post it on his thread.

The bit i could not remember back from my days in school, is how we (humans) discovered that atmospheric pressure was related to ASL. I think it involves boiling water at different altitudes but im not sure.

Cheers,

[Alephzorg]

Old thread but... are you guys planning to do the same experiments on the new planets/moons ?

[cardgame]

I think knowledge of Jool's atmo could certainly benefit any craft with insanely elliptical orbits and help them plan aerobraking maneuvers.