Can someone tell me what I'm doing wrong here?

[Cham]

Bob,

here's the code I'm using right now for Viking 1 :

Code: Select all

"Viking 1 B" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "viking.3ds"
   Beginning "1976 07 20"
   Radius 0.0025 # 5 m diameter *roughly*
   LongLat [-47.95 22.53 0.0025]

   Orientation [157.47 1 0 0]
   RotationOffset 178.055

   Albedo 0.50
}


and here's a comparison with Jack's position (both models are superposed). It's really the same position, except that there's an 180 degrees offset and I don't kow yet how to correct it :

[SU(3)xSU(2)xU(1)]

This code does place the Viking 1 lander in its approximate location and with a fairly level appearance on the surface of Mars.

Bob,

I have noticed, that you hadn't changed third number in LongLat in your Viking ssc (it's 0.00139 - the same as for Mars Pathfinder). This number is the altitude of the object over planet's surface in kilometers. To be more precise this is the altitude of the object's center. Thats why, it should be greater than zero by a value which is close to object's radius. I've obtained it as precisely as I could using quite primitive method of "trials and corrections".

As far as I remember Viking lander is bigger than Mars Pathfinder, so third number in LongLat should be bigger. I have 0.0017 for both Vikings, but i don't know if you are using the same model. I downloaded the model of Viking lander from CM.

Paul

[Cham]

And here's my SSC code for Viking 2 :

Code: Select all

"Viking 2 B" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "viking.3ds"
   Beginning "1976 07 20"
   Radius 0.0025 # 5 m diameter *roughly*
   LongLat [-225.72 47.97 0.0025]

   Orientation [132.03 1 0 0]
   RotationOffset 0.285

   Albedo 0.50
}


[SU(3)xSU(2)xU(1)]

It's really the same position, except that there's an 180 degrees offset and I don't kow yet how to correct it

Cham,

Just add 180 to RotationOffset. I have 358.055

Paul

[Cham]

Just add 180 to RotationOffset. I have 358.055

I already tried that, but it's flipping the legs up and with a wrong inclination !

[BobHegwood]

This code does place the Viking 1 lander in its approximate location and with a fairly level appearance on the surface of Mars.

Bob,

I have noticed, that you hadn't changed third number in LongLat in your Viking ssc (it's 0.00139 - the same as for Mars Pathfinder). This number is the altitude of the object over planet's surface in kilometers. To be more precise this is the altitude of the object's center. Thats why, it should be greater than zero by a value which is close to object's radius. I've obtained it as precisely as I could using quite primitive method of "trials and corrections".

As far as I remember Viking lander is bigger than Mars Pathfinder, so third number in LongLat should be bigger. I have 0.0017 for both Vikings, but i don't know if you are using the same model. I downloaded the model of Viking lander from CM.

Paul

Paul,

I very much appreciate all of your advice here. I will be using Martin's code as shown in his posts, and I'll play with it some more and make your suggested changes. As you have probably noticed, I am not a rocket scientist, but I am persistent if nothing else.

Thanks very much for all of your help here. You too Martin. Ain't it amazing what one can learn by asking stupid questions?

[Cham]

Now, I'm trying to built the SSC codes for MER-A (Spirit) Rover and MER-B (Opportunity) Rover. I don't know why, but these guys are tougher to do ! What are the exact landing dates for these guys ?

I also need the exact landing coordinates, since Jack's version is pretty cryptic !

[SU(3)xSU(2)xU(1)]

Cham wrote:

Just add 180 to RotationOffset. I have 358.055

I already tried that, but it's flipping the legs up and with a wrong inclination !

Cham,

I haven't noticed that you have also diffrent first parameter in Orientation.

Try this:

Code: Select all


"Viking 1" "Sol/Mars"
{
Class "spacecraft"
Mesh "viking.3ds"
Radius 0.0025 # 5 m diameter *roughly*
Beginning "1976 07 20"
LongLat [-47.95 22.53 0.0017]

Orientation [22.53 1 0 0] # Latitude in x rotation
RotationOffset 358.055
 
Albedo 0.80
}



I'm now affraid that I could have similar 180 offset in my Mars Pathfinder (so Bob too). I didn't pay any attention to it while writing my ssc file and didn't compare it with the original one

Paul

[Cham]

Argh ! I just noticed that the MER Rovers 3ds models are weirdly oriented in my modeler. This is a mistake from Jack.

Guys, take note that Jack's orientation on the ground, for all his models, is most probably unreliable. So the final orientation I'm getting compared to his isn't really important.

[BobHegwood]

Just so you guys know about it...

I copied Martin's code from the previous posts, and added the additional data as suggested by Paul.
The code below works perfectly on my version, and places the Landers where they should be as far as I can tell.

Code: Select all

"Viking 1 B" "Sol/Mars"
{
   Class         "spacecraft"
   Mesh            "Viking.3ds"
   Beginning         "1976 07 20"
   Radius         0.0025            # Roughly 5 meters in diameter.
   LongLat         [ -47.95 22.53 0.0017 ]
   Orientation      [ 157.47 1 0 0 ]
   RotationOffset      178.055
   Albedo         0.50
}

"Viking 2 B" "Sol/Mars"
{
   Class         "spacecraft"
   Mesh            "Viking.3ds"
   Beginning         "1976 07 20"
   Radius         0.0025            # Roughly 5 meters in diameter.
   LongLat         [ -225.72 47.97 0.0017 ]
   Orientation      [ 132.03 1 0 0 ]
   RotationOffset      0.285
   Albedo         0.50
}

Happy Brain-Dead Bob

[eburacum45]

Could I ask how to calculate Orientation and Rotation Offset for any particular LongLat declaration? I'm sure it's described somewhere, but I must have missed it.

[BobHegwood]

Now, I'm trying to built the SSC codes for MER-A (Spirit) Rover and MER-B (Opportunity) Rover. I don't know why, but these guys are tougher to do ! What are the exact landing dates for these guys ?

I also need the exact landing coordinates, since Jack's version is pretty cryptic !

I have also gotten these two models to display correctly on my system using Jack's original code with some modifications as described earlier in this thread. Remember too, that these rovers have moved a bit on the surface. You can find more information concerning both of them at NASA's site located HERE.

[selden]

Could I ask how to calculate Orientation and Rotation Offset for any particular LongLat declaration? I'm sure it's described somewhere, but I must have missed it.

One of Grant Hutchison's spreadsheets does it.
http://www.lepp.cornell.edu/~seb/celest ... ets.html#4

These days, however, I prefer to use Celestia's new 2-Vector BodyFrame since you don't have to recalculate anything when you move the object to a different position on the planet. I used this technique for the Sidereal Clock -- you can position it at the coordinates of your own observatory in Celestia and it'll show the right time.

Code: Select all

##########################################
# sidereal clock position

"Sidereal_Clock" "Sol/Earth"
{
   Class "surfacefeature"
   Radius 0.0002
   Mesh "model.cmod"

# change these values to place the clock wherever you want on the Earth
#          East Longitude   Latitude   Altitude (km)
   LongLat [    -116            33        1.75 ]

   FixedRotation {}
}

# make the clock always be face up, with top toward the North

Modify "Sidereal_Clock" "Sol/Earth"
{
    BodyFrame
    {
        TwoVector
        {
            Center "Sol/Earth/Sidereal_Clock"
            Primary   
            {
                Axis "-y"
                RelativePosition {Target "Sol/Earth"}
            }
            Secondary   
            {
                Axis "z"
                ConstantVector   
                {
                    Vector [ 0 0 1]
                    Frame {  BodyFixed { Center "Sol/Earth" } }
                }
            }
        }
    }
}

You'll have to change the Axis names depending on how the model is oriented by the 3D modelling software. A simpler method probably will be available in v1.6.0.

[Cham]

I successfuly placed Opportunity and Spirit rovers at their proper landing location, with landing date. The position is much more precise than with Jack's addon. I had to edit the model, because of the wrong orientation. Now, we only have to use a single 3ds file, instead of two similar models with Jack's addon (so an economy of about 1.3 MB), and we can use the same model to make the rover to run on Mars !

Here's a comparison of the landing site. MOLA map :

MOLA_opportunity.jpg

and a view from Celestia :

opportunity.jpg

Note the label problem on this view. This is a bug I already reported to Chris but never got a fix (Chris ?).

Here's the SSC code for the rovers :

Code: Select all

"MER-A (Spirit) Rover" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "spirit.3ds"
   Beginning "2004 01 04"
   Radius 0.0009 # 1.8m diameter *roughly*
   LongLat [175.4785 -14.5718 0.0009]
   Orientation [194.5718 1 0 0]
   RotationOffset 41.4835
   Albedo 0.80

   InfoURL "http://en.wikipedia.org/wiki/Spirit_rover"
}

"MER-B (Opportunity) Rover" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "spirit.3ds"
   Beginning "2004 01 25"
   Radius 0.0009 # 1.8m diameter *roughly*
   LongLat [354.47 -1.94 0.0009]
   Orientation [181.94 1 0 0]
   RotationOffset 220.475
   Albedo 0.80

   InfoURL "http://en.wikipedia.org/wiki/Opportunity_rover"
}


My zipped spirit.3ds model is about 364KB, so it's a bit too big to post it here.

[Cham]

Could I ask how to calculate Orientation and Rotation Offset for any particular LongLat declaration? I'm sure it's described somewhere, but I must have missed it.

To respond to this important question :

You have Long and Lat coordinates :

LongLat [a b c]

Then use Orientation [180 - b, 1, 0, 0] (without ,)
and RotationOffset a + 90 + Planet_RotationOffset (modulo 360)

That's all. Easy !

Here's the final code I'm using for the Viking landers (more precise than Jack's) :

Code: Select all

"Viking 1" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "viking.3ds"
   Beginning "1976 07 20"
   Radius 0.0025 # 5 m diameter *roughly*
   LongLat [-47.967 22.48 0.0025]
   Orientation [157.52 1 0 0]
   RotationOffset 178.038
   Albedo 0.50

   InfoURL "http://en.wikipedia.org/wiki/Viking_1"
}

"Viking 2" "Sol/Mars"
{
   Class "spacecraft"
   Mesh "viking.3ds"
   Beginning "1976 07 20"
   Radius 0.0025 # 5 m diameter *roughly*
   LongLat [-225.737 47.967 0.0025]
   Orientation [132.033 1 0 0]
   RotationOffset 0.268
   Albedo 0.50

   InfoURL "http://en.wikipedia.org/wiki/Viking_2"
}


[chris]

Andrea, I would appreciate some suggestions on how to improve the documentation. Vincent, Selden, myself, and others have been contributing to the Celestia WikiBook, which has a lot of information on creating SSC files: http://en.wikibooks.org/wiki/Celestia/SSC_File. How could it be better organized? Would more tutorials be useful? More examples?--Chris

Chris, sorry if my post appeared as criticism to you and the other developers, this was not my intention.
In my opinion the problem (or MY problem, may be I'm the only one having it) is that, while I was used to and appreciated a lot e.g. Don Goyette's cel scripting guide, clearly written and filled with many examples, the other stuff made up to now is resulting, at least for me, in a plethora of information spread in a lot of posts, without any "compendium" of similar shape.
Yes, I know we have the Wiki ssc instructions page, and many more (Trajectories-Rotation Models-Using JPL Ephemerides with Celestia-Reference Frames), but it's missing a lot of examples, perhaps most of them, and this makes difficult and hard to understand a matter that, believe me, is not so well known by many Celestians, even if probably most of them will never admit it.

Well, I do take this as criticism, but it is useful criticism. I will try to supplement the Wiki pages with more examples, though it will take time.

As you say, the Wiki pages on ssc (as all Wiki pages), are a collaborative gathering of information written and thought by different people, with different experience, feeling and behaviour with the subject.
For this reason I’m dreaming of a one-man instruction file, containing a lot of practical examples, that as you know are the best way to understand the matter in a shorter time.

I agree that it would be great to have such a guide. The documentation on the Wiki is rather technical, and I make no apologies for that: such documentation needs to exist. But, it could be better organized and illustrated with more examples and diagrams. It still would not take the place of a friendlier guide to Celestia add-on creation. There are two classic books documenting OpenGL: one is the Reference Manual, the other the Programming Guide. The Reference Manual is comprehensive, with pages organized alphabetically by function name. The Programming Guide is organized by topic, starting from basic 3D concepts and building to more advanced ideas. Celestia needs a Programming Guide.

BTW, just an example on Wiki problems:

Beginning f or "AAAA MM DD HH:MM:SS"
Specifies a time before which the object doesn't exist.
The Beginning time may be provided as a floating point number, in which case it is interpreted an astronomical Julian date, or it may be provided as a quoted string, in which case it is interpreted as a Gregorian date.
If it is a quoted Gregorian date, AAAA MM DD = year, month, day (integers); HH:MM:SS = hour, minute, second (integers). Since version 1.3.1, Celestia converts these time-stamps into Julian Dates internally. A date to Julian Date and back converter can be found at the U.S. Naval Observatory
http://aa.usno.navy.mil/data/docs/JulianDate.html

Sincerely, do you think that all Celestians know what “floating point number” is meaning?
Or what's the Astronomical Julian Date?
Wasn’t perhaps needed to explain that the JD is written this way: 2443711.139953?
More: why the beginning date is given as “AAAA MM DD” and no more as YYYY MM DD” as previously?
More: in the previous ssc definitions, written by Ulrich and Bob, it was given that "beginning" and "ending" could be written without the seconds, or with the AAAA MM DD only, so that it was possible to write as follows:
Beginning "1989 10 19 92:47:25" or
Beginning "1989 10 19 92:47" or
Beginning "1989 10 19"
Is this still OK?
If yes, it's missing in the wiki.
More. The web link to the U.S. Naval Observatory is OFF from many months, but this is the new one
http://www.aavso.org/observing/aids/jdcalendar.shtml

Yes, there are inadequacies in the documentation. Some more examples would help a lot, the AAAA instead of YYYY (presumably A = annum) was a poor choice, and there needs to be clarification about what date formats are allowed. I do think that terms like floating point number and Julian Date are appropriate as well--they have precise means that are widely understood by a certain audience. Without them, the concepts can remain fuzzy.

Please don't say me "why don’t you make it?", I would be very happy to be able to give my help on this, I always try to give my help with the little things I'm able to do, but I'm missing at least two most important characteristics, both highly needed for this task:
English is not my mother tongue (so I need a lot of time to understand what I read, and even more to try to write something intelligible),
and, most important,
I have not the culture needed to be able to modify the wiki ssc, sorry.

I won't ask you to make it, but I will ask you to help out. The whole point of making the documentation available as a Wiki is to get more people to contribute to it. You don't have to write new documentation--simply fixing the broken links to the Julian Date calculator is a useful contribution. Just click edit on the page and make the change.

Given I’m trying to give suggestions, I see that in the last months there have been a lot of patches, SVN, beta releases and so on, chasing each other at very short intervals, and this produces a lot of confusion in many people, I think.
It looks like, instead of officialising the already established new stuff, you and the other developers are going on and on searching for new improvements.
I beg your pardon Chris, I'm and old man, so be patient with me, please, but I feel that following all Celestia partial and beta improvements is becoming harder and harder as time goes by, given the missing of clear and SIMPLE explanations on how to apply them.
We have no more the time we had previously, between one release and the other, that allowed most of us to digest innovations, and to learn to use and appreciate them.
I'm sure that most of the new stuff is not used by most of people, due to the increasing difficulties to learn to use it.
Have you got seen how many people are still using older releases?
Allow me to remember what a high school professor told me many many years ago:
“...the best project, if poorly documented, will always be overtaken by another that, even if of lower quality, is very well documented”.
As I told, this is my feeling, but I would like that at lest once the silent people, i.e. the thousands of Celestians that never or very rarely write in the forum, would change their way of life, and may tell us if I’m wrong or right.
Bye and, as always, a lot of appreciation for all what you and all the other developers are doing to make Celestia better and better.
Friendly

Your suggestions are certainly appreciated.

The SVN versions and patches are a good thing; they are intended to allow people to experiment with new features and give feedback before the official release. I expect that most people are content to wait for an official release, which is just fine. That's how I am with most of the software that I'm interested in.

While 1.6.0 is under development, it would be useful to have some good overviews of the new features. For that purpose, I've created this new page on the WikiBook:

http://en.wikibooks.org/wiki/Celestia/160Files

Hopefully, the feature descriptions are good enough to be reused in some more official documentation. I will continue to add to the page and add more details.

--Chris

[BobHegwood]

I successfuly placed Opportunity and Spirit rovers at their proper landing location, with landing date. The position is much more precise than with Jack's addon. I had to edit the model, because of the wrong orientation. Now, we only have to use a single 3ds file, instead of two similar models with Jack's addon (so an economy of about 1.3 MB), and we can use the same model to make the rover to run on Mars !

This is exactly what I did, but I included a different altitude parameter so that the mesh center lies approximately 1.5 meters above the surface of Mars
Used 0.0000323 as the LongLat height.
Works equally well for both rovers, and places them perfectly on the surface of Mars.

Note the label problem on this view. This is a bug I already reported to Chris but never got a fix (Chris ?).

Do not see this problem on my system, Martin. Just FYI...

[BobHegwood]

Paul,
I sent you a PM, but I guess you don't have your preferences sent to receive (or be notified) of such events. Just for your information here, the following is what I sent in that PM (which has now been deleted since I'm posting it here.)

Paul,

Sorry to bother you, but I just wished to express my appreciation for all of your help in understanding what one has to do in order to place an object on the surface of a planet. I have now added a link on my home page which will take others to the thread I started, and all of your help.

Again, many thanks for your patience and understanding here. I am really not all that smart, but I really DO have an interest in, and get much enjoyment from, the exploration of the Universe.

Take care, Brain-Dead Bob

I mean what I said here, my friend. I learned many things about the location of objects on the surface of planets from your help here, so I just wanted to make certain that you knew how much I appreciated your help.

Once again, many thanks my friend.

[Cham]

Here's a replacement for the Apollo landing sites from Jack's SSC. Position should be more precise than Jack's version :

Code: Select all

# Coordinates from this NASA web site :
# http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo_tables.html

"Apollo 11 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2440423.13726852  #1969 07 20 15:17:39
   Ending 2440424.03751157  #1969 07 21 12:54:01
        Radius 0.0041667

   LongLat [23.47298 0.67409 0.001]
        Orientation [0.67409 1 0 0]
        RotationOffset -28.52702
        Albedo 0.80
}

"Apollo 11" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2440424.03751157  #1969 07 21 12:54:02
        Radius 0.0041667

   LongLat [23.47298 0.67409 0.001]
        Orientation [0.67409 1 0 0]
        RotationOffset -28.52702
        Albedo 0.80
}

"Apollo 12 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2440544.57957176  #1969 11 19 01:54:35
   Ending 2440545.89290509  #1969 11 20 09:25:47
        Radius 0.0041667

   LongLat [-23.41930 -3.01381 0.001]
        Orientation [-3.01381 1 0 0]
        RotationOffset -75.4193
        Albedo 0.80
}

"Apollo 12" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2440545.89290509  #1969 11 20 09:25:48
        Radius 0.0041667

   LongLat [-23.41930 -3.01381 0.001]
        Orientation [-3.01381 1 0 0]
        RotationOffset -75.4193
        Albedo 0.80
}

# Apollo 13
#
# If you don't know why Apollo 13 didn't land on the moon,
# go outside & bang your head off the ground repeatedly.
#
#

"Apollo 14 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2440987.67929398
   Ending 2440988.63281250
        Radius 0.0041667

   LongLat [-17.47139 -3.64544 0.001]
        Orientation [-3.64544 1 0 0]
        RotationOffset -69.47139
        Albedo 0.80
}

"Apollo 14" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2440988.63281250
        Radius 0.0041667

   LongLat [-17.47139 -3.64544 0.001]
        Orientation [-3.64544 1 0 0]
        RotationOffset -69.47139
        Albedo 0.80
}

"Apollo 15 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2441163.26144676
   Ending 2441167.04956019
        Radius 0.0041667

   LongLat [3.63400 26.13224 0.001]
        Orientation [26.13224 1 0 0]
        RotationOffset -48.366
        Albedo 0.80
}

"Apollo 15" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2441167.04956019
        Radius 0.0041667

   LongLat [3.63400 26.13224 0.001]
        Orientation [26.13224 1 0 0]
        RotationOffset -48.366
        Albedo 0.80
}

"Apollo 16 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2441428.39137731
   Ending 2441431.35125000
        Radius 0.0041667

   LongLat [15.49859 -8.97341 0.001]
        Orientation [-8.97341 1 0 0]
        RotationOffset -36.50141
        Albedo 0.80
}

"Apollo 16" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2441431.35125000
        Radius 0.0041667

   LongLat [15.49859 -8.97341 0.001]
        Orientation [-8.97341 1 0 0]
        RotationOffset -36.50141
        Albedo 0.80
}

"Apollo 17 LEM" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_full.3ds"
   Beginning 2441663.12149306
   Ending 2441666.24626157
        Radius 0.0041667

   LongLat [30.77475 20.18809 0.001]
        Orientation [20.18809 1 0 0]
        RotationOffset -21.22525
        Albedo 0.80
}

"Apollo 17" "Sol/Earth/Moon"
{
        Class "spacecraft"
        Mesh "apolloLM_desc.3ds"
   Beginning 2441666.24626157
        Radius 0.0041667

   LongLat [30.77475 20.18809 0.001]
        Orientation [20.18809 1 0 0]
        RotationOffset -21.22525
        Albedo 0.80
}


[ANDREA]

Chris, sorry if my post appeared as criticism to you and the other developers, this was not my intention.

Well, I do take this as criticism, but it is useful criticism. I will try to supplement the Wiki pages with more examples, though it will take time.

I’m sure that it would be very appreciated by many people here.

As you say, the Wiki pages on ssc (as all Wiki pages), are a collaborative gathering of information written and thought by different people, with different experience, feeling and behaviour with the subject. For this reason I’m dreaming of a one-man instruction file, containing a lot of practical examples, that as you know are the best way to understand the matter in a shorter time.

I agree that it would be great to have such a guide. The documentation on the Wiki is rather technical, and I make no apologies for that: such documentation needs to exist. But, it could be better organized and illustrated with more examples and diagrams. It still would not take the place of a friendlier guide to Celestia add-on creation. ….

I hope that it will be possible in the future.

BTW, just an example on Wiki problems:…..

Yes, there are inadequacies in the documentation. Some more examples would help a lot, the AAAA instead of YYYY (presumably A = annum) was a poor choice, and there needs to be clarification about what date formats are allowed. I do think that terms like floating point number and Julian Date are appropriate as well--they have precise means that are widely understood by a certain audience. Without them, the concepts can remain fuzzy.

Chris, I well know that this is right, I was only meaning that it would be helpful for many people to be informed too on what is a “floating point number” and what means the “Julian Day” notation (OK, it’s possible to search for it in the web, but if for every unknown technical or scientific word the newbie has to go searching for explanations, I fear that he will stop reading, if not sufficiently motivated). Perhaps a link to an explanatory page could be added in the Wiki itself, IMHO. If you agree I can try to do it.

Please don't say me "why don’t you make it?"….

I won't ask you to make it, but I will ask you to help out. The whole point of making the documentation available as a Wiki is to get more people to contribute to it. You don't have to write new documentation--simply fixing the broken links to the Julian Date calculator is a useful contribution. Just click edit on the page and make the change.

OK, I'm ready to give my minimal help, so I’ll do a check of the Wiki ssc page and will change what I'm sure about, and advice here for what I’m doubtful.

Given I’m trying to give suggestions, … I feel that following all Celestia partial and beta improvements is becoming harder and harder as time goes by, given the missing of clear and SIMPLE explanations on how to apply them.....

Your suggestions are certainly appreciated. The SVN versions and patches are a good thing; they are intended to allow people to experiment with new features and give feedback before the official release. I expect that most people are content to wait for an official release, which is just fine. That's how I am with most of the software that I'm interested in.

Chris, I agree on this, I installed and tested all the recent SVN, as Vincent’s LUA Edu Tools and m3ntol patch for constellation names and orbit/label colors. I’m only saying that the documents regarding all this "under development" stuff are not gathered in a single thread, as perhaps would be the best solution, but spread among a lot of posts and threads.
What do you think abour creating a "Celestia Development" subforum, named e.g. "Celestia Development Docs"?

While 1.6.0 is under development, it would be useful to have some good overviews of the new features. For that purpose, I've created this new page on the WikiBook:
http://en.wikibooks.org/wiki/Celestia/160Files
Hopefully, the feature descriptions are good enough to be reused in some more official documentation. I will continue to add to the page and add more details.--Chris

Chris, this page is absolutely clear and pleasant to be read.
Now I have a clearer idea on many of the ssc files new options, that I previously lost among the many posts and threads about them.
I think, and I hope, that many other people will agree that this is the right way to implement documentation for people not directly involved with the development (most of Celestians, therefore).
Very appreciated.
BTW, may I suggest to split this thread, merging the few posts like this regarding the documentation, and putting them in another thread, perhaps in “Celestia Users”?
Do you agree?

Bye and thanks a lot for your precious work and patience.

Andrea