Real-time ISS Postions

[insanity]

I haven't seen a thread with the latest ISS elements, so I decided it would be good to. I might update every now and then if people are interested. Anyways, just copy and paste this iss over one a .scn file set to current/date time. I usually use the Solar System at Present (/orbiter/scenarios/solar system/today.scn) and just write the elements over the position.

 

[insanity]

If anyone is interested, today's updated real-time position is:

ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  ELEMENTS 6726948.44214954 0.00075860 35.49446721 56.85741741 340.55457247 74.06047247 55051.49202819
  AROT 30.00 -0.00 50.00
  IDS 0:588 100 1:586 100 2:584 100 3:582 100 4:580 100
  NAVFREQ 0 0
  XPDR 466

If you copy and paste this over the ISS in the Solar System at Present scenario you will have a fairly good estimation of where the ISS is.

 

[thelastwaltz]

What converter program are you using?

 

[kneejo]

I've tried eq_to_el and tle2ecl but they both give unsatisfying results.. or maybe I'm a fool, but then, these programs don't seem to be fool-proof.

Any advice on the above programs (or a better alternative) is welcome.

 

[tblaxland]

What converter program are you using?

I've used data from this page: http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html

Two approaches I have used successfully in the past:

1. Put the J2K Cartesian coordinates into the scenario file. Remember to swap the y & z components of the vectors so that they are in Orbiter's left-hand format. Also, the state vectors in the scenario file are assumed to be for the epoch of the scenario file so the MJD at the top of the scenario file must match the vector time given on that page.

2. Put the TLEs from that page into a text file and read them into [ame="http://www.orbithangar.com/searchid.php?ID=2617"]Scenario Editor TLE[/ame]. The date does not need to match the TLE epoch since the SGP4 algorithm in will propagate the elements for you.

 

[hribek]

Is the Scenario Editor TLE compatible with Orbiter 2010? I've just tried it and it doesn't crash or anything, just works improperly. Upon loading TLEs for ISS retrieved from the website linked above, it reports that the MJD of the TLEs is in the future, although the simulation date is set to current.

---------- Post added at 10:04 PM ---------- Previous post was at 08:17 PM ----------

Eh, now I'm confused about as much as the program is ... the data that NASA provides seem to have epoch dates in mid-July :idk:

Here's the latest for reference:

TWO LINE MEAN ELEMENT SET

ISS
1 25544U 98067A 10195.51171992 .00016717 00000-0 10270-3 0 9143
2 25544 51.6479 90.7069 0009830 73.3725 286.8516 15.72415368 27773


Satellite: ISS
Catalog Number: 25544
Epoch time: 10195.51171992 = yrday.fracday
Element set: 914
Inclination: 51.6479 deg
RA of node: 90.7069 deg
Eccentricity: .0009830
Arg of perigee: 73.3725 deg
Mean anomaly: 286.8516 deg
Mean motion: 15.72415368 rev/day
Decay rate: 1.67170E-04 rev/day^2
Epoch rev: 2777
Checksum: 340

Coasting Arc #15 (Orbit 2776)
---------------------------------------

Vector Time (GMT): 2010/195/12:00:00.000
Vector Time (MET): N/A

I just don't get it. 195th day in 2010 is 14th July. Yeah, dividing 195 by 30 gives you roughly 6.5 - now, what's wrong?
Weight (LBS) : 813514.6

---------- Post added at 10:28 PM ---------- Previous post was at 10:04 PM ----------

BEGIN_ENVIRONMENT
System Sol
Date MJD 55391.5
END_ENVIRONMENT

ISSrojectAlpha_ISS
STATUS Orbiting Earth
RPOS 3795037.25 -2753230.55 -4841450.76
RVEL -1995.164525 -7009.957895 2430.699101

- this scenario seems to have ISS with orbit inclination of 76.13 degrees (rel. to equator)

Well, on the upside, my ISS didn't burn up in atmosphere, end up inside the Earth or escape yet. So I'm not doing that bad.

 

[insanity]

I just ran the TLEs and got a similar inclination, but about the right location.

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  ELEMENTS 6731001.67364949 0.00098060 74.27096590 166.09357079 185.01621065 296.12221065 55377.42561005
  AROT 30.00 0.00 50.00
END

 

[hribek]

That's weird. When I used the TLE scenario editor, the inclination was correct and all (provided that I click "Apply" after loading the orbital elements once you load the text file with TLE), but as I said the date seems totally off, and so is the LAN (when compared to heavens-above, NASA TV, AND seeing it just outside on the night sky ...)

The 1st level of checking if the elements are right would be if the inclination fits and LAN fits relative to ground at present time, which it doesn't seem to. I'm also wondering if the STS Expansion pack scenarios use then-current ISS elements or if just the Inc and LAN are adjusted to fit.

---------- Post added at 11:06 PM ---------- Previous post was at 10:53 PM ----------

Well it seems that NASA provides predictions for the next days or so - duh. Seeing what TLEs heavens-above.com uses (the ones right on top of the page), I tried to load those vie the scenario editor TLE, and it worked - though, the PeA and ApA are 20km higher than H-A would suggest.

 

[insanity]

Ooh, I made a bit of a mental lapse on my last scenario. It's correct, I was just reading the inclination from the wrong source in the orbit mfd.

So, here is a scenarino I setup for the realtime ISS position

BEGIN_ENVIRONMENT
  System Sol
END_ENVIRONMENT

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  ELEMENTS 6731001.67364949 0.00098060 74.27096590 166.09357079 185.01621065 296.12221065 55377.42561005
  AROT 30.00 0.00 50.00
END

I use eq_to_ecl.exe which coverts TLEs from celestrak into orbiter elements.

It was about right on for altitude, too

 

[hribek]

Yeah, that seems to work best for me as well. Many thanks!

 

[streb2001]

Stellarium has a plugin that gets ISS and other positions from celestrak for almost realtime updates. Is there anything preventing an Orbiter module doing the same thing ie. getting realtime info from the web and positioning the ISS? Indeed has this already been done?

s2k1

 

[tblaxland]

Indeed has this already been done?

Not specifically, but related concepts have been demonstrated:

[ame="http://www.orbithangar.com/searchid.php?ID=3868"]Heavens traffic 090405[/ame] - reads TLEs from file.
[ame="http://www.orbithangar.com/searchid.php?ID=4641"]Orbiter Radio MFD 2010[/ame] - retrieving information from the net​

 

[streb2001]

Thanks, I'll have a look if only out of interest for now.

 

[Kendo]

If I remember correctly, someone, I can,t remember who, did this around 3 or 4 years ago. He had a link also to download the latest elements etc. Insanity, good work by the way.

 

[insanity]

Haven't updated this in awhile, but thought I ought to!
Current as of 10 PM (PDT) August 5, 2010!

As always, just paste this iss into a scenario set to the present MJD.

ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  ELEMENTS 6732697.87803642 0.00069900 31.21158425 322.73147314 165.99206723 122.04866723 55413.85839317
  AROT 30.00 0.00 50.00
END