Can Celestia Use TLEs?

[Iowa Tom]

Hello,

I'm trying to find user friendly planetarium software that we can afford to install on multiple computers at the small school where I teach. What I really want it for is to make manmade satellite predictions for curriculum I'm writing for my graduate degree. I need to see the tracks as well as the satellites displayed.

My question is this, does Celestia work with TLEs or other orbital elements?

Thanks,

Tom

[Malenfant]

Sorry, what are "TLEs"? I'm not familiar with the acronym...

I'm pretty sure that people have used JPL's Horizons website/software to import satellite orbits. And I know that Celestia can show satellite orbits, don't know about tracks on the surface below though.

But I think you should be able to use Celestia for at least some of what you're after, I'm just not familiar enough with it all myself to be able to be more specific. I'm sure others here will chip in though.

[BrainDead]

Sorry, what are "TLEs"? I'm not familiar with the acronym...

Mr. Malenfant,

I'm certain that Selden can explain better than myself, but I believe that
TLE's are simple "Two-Line-Element" coordinates for use in tracking objects
in space. Aren't these related to Celestia's XYZ files in some manner?

Thanks, Brain-Dead

[chris]

Celestia can't yet use TLEs directly. But, there's a spreadsheet that will convert them to elliptical elements useable in Celestia:

http://www.lepp.cornell.edu/~seb/celest ... ets.html#3

It's an Excel spreadsheet. If you don't have Excel, you can use the free OpenOffice suite instead (available from openoffice.org.)

--Chris

[Malenfant]

Sorry, what are "TLEs"? I'm not familiar with the acronym...

Mr. Malenfant,

I'm certain that Selden can explain better than myself, but I believe that
TLE's are simple "Two-Line-Element" coordinates for use in tracking objects
in space. Aren't these related to Celestia's XYZ files in some manner?

Thanks, Brain-Dead

Thanks, I'd never heard of those before (that said, I think I might have seen some of these before, but not realised that was the name for them)

[selden]

To actually locate and track LEO satellites in your sky, you might want to consider one of the programs designed for doing that.

While TLEs can be translated into Celestia's EllipticalOrbit format using the spreadsheet Chris mentions, you may be disappointed in how poorly Celestia can predict whether you might actually be able to see a satellite from your location.

Celestia represents the Earth by a perfect spheroid (an oblate one if you want). The Earth's surface is much more irregular than that. As a result, the directions toward satellites in Low Earth Orbit aren't as accurate as you would like.

[Chuft-Captain]

There's also websites that track satellites.
I cannot say how accurate or up-to-date they are but I understand that their data comes from NORAD.

http://www.n2yo.com/

http://www.heavens-above.com/

They won't of course do planetarium style display

[Iowa Tom]

I am aware of various web based satellite tracking programs and shareware. Celestia I was hoping might work to demonstrate certain orbital parameters like inclination. As far as using it to make predictions, I don't need it for that. I usually use Heavens-Above. I would like to show some animations of satellites moving overhead. Can Celestia do that?

The reason I don't just download it and look around is I am hard pressed for time and don't want yet another program that I will not use a lot. I have purchased a low end version of Starry Night but was disappointed with several things. The image is supposed to be lifelike. That it is; to the degree that I find that I have to turn to the room lights off to see it! I also found that I cannot change the preferences I need to change in the low end software. To upgrade I will have to pay much more than I would have had to pay if I would have started with the fancier CD. Not happy there.

The main problem I have is for licensing for many computers in the computer lab. The boss told us we shouldn?€™t be spending any $ that we don't have to.

Another problem I?€™m having right now is that I wrote a lot of curriculum that used Google Earth for animations of flyovers by satellites. The computer guy thought that would not be a problem. However, we have discovered that none of the computers here at school are compatible with that powerful of a program. Back to the drawing board! Not so much a problem this summer when I wrote it but not at all good now that I am in the swing of teaching 5 subjects in science every day.

Thanks for the help!

Tom

[Red1530]

I am aware of various web based satellite tracking programs and shareware. Celestia I was hoping might work to demonstrate certain orbital parameters like inclination. As far as using it to make predictions, I don't need it for that. I usually use Heavens-Above. I would like to show some animations of satellites moving overhead. Can Celestia do that?

The reason I don't just download it and look around is I am hard pressed for time and don't want yet another program that I will not use a lot. I have purchased a low end version of Starry Night but was disappointed with several things. The image is supposed to be lifelike. That it is; to the degree that I find that I have to turn to the room lights off to see it! I also found that I cannot change the preferences I need to change in the low end software. To upgrade I will have to pay much more than I would have had to pay if I would have started with the fancier CD. Not happy there.

The main problem I have is for licensing for many computers in the computer lab. The boss told us we shouldn?€™t be spending any $ that we don't have to.

Another problem I?€™m having right now is that I wrote a lot of curriculum that used Google Earth for animations of flyovers by satellites. The computer guy thought that would not be a problem. However, we have discovered that none of the computers here at school are compatible with that powerful of a program. Back to the drawing board! Not so much a problem this summer when I wrote it but not at all good now that I am in the swing of teaching 5 subjects in science every day.

Thanks for the help!

Tom

Celestia should be able to show orbet inclination. I am posting an image of what I think you are looking for.

[Iowa Tom]

Thanks for the replies.

The type of inclination that I am looking for is exemplified in this graphic.

[selden]

Celestia shows orbit paths, but it does not show the details of the associated coordinate systems. You will have to use Addons in order to display their relationships. I've put together a few Addons that do part of this, but they certainly don't do everything that I think you want. I'm actually surprised that nobody has put together a set of Addons that would do this.

You might take a look at
http://www.lepp.cornell.edu/~seb/celest ... cules.html
to see if any of them are useful for what you're trying to do.

[selden]

Here's a picture of Celestia displaying satellite orbits and the Earth's axis and coordinate grid:



.

[Iowa Tom]

Here's a picture of Celestia displaying satellite orbits and the Earth's axis and coordinate grid:



.

Did you use "Grant Hutchison's Spreadsheets" to make the traces that you have here? I'm sure I can figure this out eventually but to save me time can someone tell me (1) if I Celestia displays the Earth well enough that you can tell where Florida and England are? (2) Can I place the desired circular orbit of say, a 58 degree inclination, right over where Cape Canaveral would be then turn the Earth image so that I may follow the path that that inclination will take if launched generally NE from the Cape? It would not matter that the orbit is completely around the Earth to start with. My objective is to show where the Shuttle first goes as it's launched toward the ISS. It passes over Europe in the first pass.

Thanks!

Tom

[selden]

The satellite tracks shown are included with Celestia. The ISS and Hubble are included, for example. No spreadsheets were involved for this particular picture, although their orbits aren't the same as they are now.

Florida and England are easily recognizable with the resolution of surface textures included with Celestia. Seeing the details of Cape Canaveral or inner-city London requires installing a high resolution Virtual Texture Addon.

You can place orbits however you want if you undertand Keplerian orbital paramenters. TLEs and Grant's spreadsheet can be used to set up the ISS and shuttle orbits appropriately.

You really should download Celestia and play with it. And read the User's Guide that's on the MotherLode.

[DonAVP]

To put on my sale hat on. I second Selden. I think you will be pleasantly suprised. I take it that you are mostly interested in near Earth satellites. You can go to Motherload (this is were people all over the planet have uploaded add-ons of all kinds) download a 2K or 4K image of the Earth. Put the image in the highres folder and type 'R' to increase the resolution of the image when you get Celestia running.

One issue, the school computers may not have enought video RAM. If they are a few years old they may only have 8 Megs or so. This could be a problem. I beleive there is a spec on min. system requirements at Motherload.

You mentioned time, this program is very powerful and does take a little learning. By learning I am referring to about 20-30 keyboard shortcuts. You can use the mouse but the keyboard really opens up the full power of the program. Realize that you can also fly to any of the planets, most asteriods, comets, thousands of stars, galaxies and nebula. There are 3 or 4 space craft in the standard download. You can also view eclipse and run or write scripts to control how the program will run. There is a whole section and group of people developing the program for educational pursuits. Just my 2 cents worth.

Don

[Iowa Tom]

I spent about 10 hours a day for a month learning about satellite orbits and coming up with my own ideas on how to have my students see for themselves what inclination means and what eccentricity is along with the differences between low Earth, intermediate Earth, Molniya orbits and geocentric orbits are. The idea of using Celestia is primarily to help myself to get by being in a small private school w/o the funds to pay $400 or more for software for 16 computers. I have figured out a way to use Google Earth to show some truly remarkable things like how fast the ISS moves over the ground given your eye to screen distance for a given magnification on the screen. That will now have to be a demonstration since none of the computers at school, I found out, can handle Google Earth (GE); that after all that work! I'll have to bring in my laptop to show them.

The other thing I REALLY want them to do themselves is follow instructions that I write for them to will set up a pass of the ISS over the launch pad in Cape Canaveral. This does NOT have to be high resolution, although that would be nice. I simply want them to see what direction the shuttle goes when it's launched to catch the Station.

Another thing I want them to see works exceedingly well using GE. That is, showing what the inclination will be of any satellite that is launched straight east (azimuth 90 degrees) from the Cape, like the Hubble was. When you launch eastward the orbit intersects the equator at an angle equal to your latitude. That seems counterintuitive but the computer shows it happen. That I like! Now I know why it happens but to see the orbit laid out and being able to follow it around the Earth is a BIG help.

So if I take the plunge and learn how to work with this affordable program in a way that will work with the donated hand-me-down computers we have at my school I will have accomplished much. The next step will be to produce a lab book and a presentation that I can give to other educators at a science symposium at the University nearby. Teachers will relish the savings in $ that Celestia will offer; I assure you.

Tom

I'm off to photograph the autumn colors on a weekend get away now.

[selden]

Tom,

While I don't think they go into orbital mechanics much, you might want to take a look at the lesson plans by Frank Gregorio that are on the Motherlode.

http://celestiamotherlode.net/catalog/educational.php

[Iowa Tom]

Here's a picture of Celestia displaying satellite orbits and the Earth's axis and coordinate grid:



.

Can someone tell me the shortcut keys to display the satellite (spacecraft) tracks? Also, is it possible to set the time to what you want it to be so that you can start from there? If so, please let me know the shortcut keys.

Thanks!!

I have used the spread sheet linked in another post and found that the results are remarkable!!

Tom

[selden]

Tom,

The shortcut keys are listed in the help menu.

o displays orbits

For that command to display satellite orbits, you also must have enabled spacecraft orbits in the Render/View Options menu.

You can set the time using the Time menu and then you can set a bookmark for the viewpoint using the Bookmarks menu. There aren't any keyboard shortcuts for those commands.

[Iowa Tom]

I used Grant Hutchison's, July 2003 CONVERSION OF NORAD TWO-LINE ELEMENT FORMAT TO A CELESTIA EARTH-ORBIT DEFINITION spread sheet to plot the current position of the Space Station. It seems to display the current position in longitude fairly accurately but was about 500 miles too far south in latitude.

The TLE was new. Does anyone know if this is to be expected?

Tom