Celestia Forums

HI, i am new to this most wonderful world of celestia and i am need of some advice regarding add ons. i have installed the most recent celestia ok, and down loaded some add ons but i can not get the new together. Thanks for your help in this matter (hopefully).

Please take a look at the Web page http://www.lns.cornell.edu/~seb/celestia/addon-intro.html

Unfortunately, addons are "hand crafted" and older ones don't necessarily work with the newest versions of Celestia without some modifications. The Web page mentioned above tries to help you understand how addons are assembled so you can fix them if necessary.

Seldon, thank you for the link. It fixed the problem I was having seeing nebula add ons.

I am still having some problems. I installed Jack's Huygens Probe but I can't see it. Celstia goes someplace but no spacecraft graphic when it gets there.

I installed the Venus Magellan Orbiter. It goes to the right place but no graphic of the orbiter for this one either.

I installed Jack's Mars Pathfinder & Sojourner Rover. I can see the graphic ok, but it is suspended in space. I can't get it on the surface. I've tried various different dates.

I am new to Celestia and just love it. It gives a whole new perspective to objects I read about all the time.

I downloaded and installed Celestia V1.3.1

I have a 1.6 GHz computer, 512MB RAM with a NVidia GeForce 3 with 64MB video RAM.

Thank you for any help that you may have to offer.

bassrat

Bassrat,

There are two "obvious" reasons why the Huygens probe might not be visible.

You have to be sure to download both of Jack's Huygens Probe files and copy their contents to the appropriate directories. One of its Zip archives contains only the trajectory. The one with the comment "(Version 2)" includes the model. If you don't have the model, you won't be able to see anything.

Also, The Huygens probe currently is a passenger on the Cassini spacecraft. Jack's SSC describes Hyugens when it's on its own. It is visible only briefly, during its descent to Titan. Either you have to set Celestia's simulation to that date (December 25, 2004, 05:06:00 UT), or you have to delete the Beginning and Ending directives from his ssc file.

Since Huygens' trajectory is defined using an xyz file that's valid only for the time of its fall to Titan, viewing it at dates outside the range defined in the xyz trajectory file will show the probe at one end or the other of the xyz trajectory. The probe will be at the position in space defined for the time in the trajectory that's closest to the date Celestia is simulating. Most likely, that location will be in interplanetary space -- Jupiter either won't have gotten there yet or allready will have passed by.

The Magellan probe has similar requirements. Its model files are separate from the trajectory archive, and it is no longer in orbit. You have to set Celestia to a date when it was.

Unfortunately, the official radius of Mars has changed since Jack created the SSC files describing the locations of the Pathfinder and Sojourner. Celestia v1.3.1 uses a different value than did previous versions. As a result, the models are not being drawn on the surface. Hopefully Jack will be able to update his SSC files for them. Alternatively, you can read Grant Hutchison's description of how to place objects near a fixed location on a planet and edit the SSC file yourself.

See http://www.lepp.cornell.edu/~seb/celestia/hutchison/defined_locations-130.html

Does this help?

bassrat,

What selden said!

After reading that, I had a few ideas, which could help out when you go to an object which hasn't "begun" yet. These may have been mentioned before, I can't remember...

a) If you select an object which has either not yet begun, or has ended, and then press "G" to goto the object, how about a small text display at the corner of the screen saying something like:
or similar, that would last for 10-20 seconds or so... Then people would know why they're not seeing it, and also when to go back/forward to, so they would be able to.

b) Combining together objects... For Huygens- if it was possible to "lock together" Earth, Huygens, Cassini, and Titan, so that...
If I goto Huygens:
Before 1997 (Cassini's launch) i'll go to earth (or KSC's location, but earth would be easier)
Between 1997 and Probe release in late 2004 i'll go to Cassini (since that's where Huygens is attached)
Between Probe release and Titan landing i'll go to the Huygens probe's actual position, using the Huygens xyz file
After The huygens landing, i'll goto Titan, or the landing location if the user has that installed. Again, titan would be easier.

I imagine a reference within the Huygens xyz-ssc file to something like

And then inside the .trj file, something like (can't remember dates so invented them- they'd be in julian anyway):


Good idea...? Obviously improvements are needed there...

I will get around to fixing the Pathfinder & Sojourner problem eventually, but i haven't had enough time for ages- incredibly busy at school, and this is my first forum post in like 2 weeks... I've the mid-term hols in a weeks time though, so hopefully I can fix these (and some other) things then.

Thank you Seldon. The problem was resolved by changing the date for the Huygens Probe and for the Venus Magellan orbiter. For a newbie using Celestia, I would never have figured this out on my own. I find in incredable that people are so intelligent & resourceful as to be able to write the scc scripts and create the models and a readme file and never mention the needed dates to see the object.

As for the Mars Pathfinder, it does appear to be approx 6,000km beneath the surface of Mars. I haven't yet read the link you kindly provided. Hopefully I can make sense of it and correct the Mars diameter in my V1.3.1 Celestia.

Interesting stuff. Once again, thank you for the help.

bassrat