Scenario ISS actual position

[crisk73]

Hi, I'd like to simulate the SpaceX DM-1 launch taking place on 3rd March (to date).
What I'd liketo do is to predict the position of ISS for that day and set in on a particular L39A Falcon9 scenario. I read somewhere that it has to do with inserting the actual TLE coordinates. It that possible? Thanks!

 

[Marijn]

̶C̶a̶n̶ ̶y̶o̶u̶ ̶a̶c̶c̶e̶s̶s̶ ̶t̶h̶i̶s̶ ̶u̶r̶l̶?̶ ̶

̶h̶t̶t̶p̶s̶:̶/̶/̶s̶c̶r̶i̶p̶t̶.̶g̶o...̶p̶w̶q̶3̶k̶i̶g̶-̶K̶F̶V̶9̶V̶E̶E̶C̶n̶Z̶o̶2̶W̶5̶

This one should work now: https://script.google.com/macros/s/AKfycbxJweWn9kqD1hQ3i0hKa681l4jMbeENIIaEm20B5ty6JHrTvP_g/exec

̶I̶t̶'̶s̶ ̶a̶ ̶l̶i̶t̶t̶l̶e̶ ̶p̶r̶o̶j̶e̶c̶t̶ ̶I̶ ̶f̶o̶r̶g̶o̶t̶ ̶a̶b̶o̶u̶t̶.̶ ̶I̶ ̶a̶m̶ ̶n̶o̶t̶ ̶s̶u̶r̶e̶ ̶w̶h̶e̶t̶h̶e̶r̶ ̶y̶o̶u̶ ̶n̶e̶e̶d̶ ̶t̶o̶ ̶b̶e̶ ̶a̶u̶t̶h̶o̶r̶i̶z̶e̶d̶ ̶t̶o̶ ̶a̶c̶c̶e̶s̶s̶ ̶i̶t̶.̶ ̶

It shows the actual position of the ISS in an Orbiter friendly format.

---------- Post added at 02:06 PM ---------- Previous post was at 01:50 PM ----------

̶I̶ ̶a̶m̶ ̶n̶o̶t̶ ̶s̶u̶r̶e̶ ̶w̶h̶a̶t̶ ̶s̶t̶a̶t̶e̶ ̶m̶y̶ ̶a̶p̶p̶ ̶i̶s̶ ̶i̶n̶.̶ ̶I̶t̶ ̶c̶o̶u̶l̶d̶ ̶b̶e̶ ̶b̶r̶o̶k̶e̶n̶.̶ ̶
But right now it serves this data: ELEMENTS 6785440.079818818 0.00050920 44.23534169 277.60723740 302.47481751 27.50231751 59154.09394694

I just checked it. It works.

If you put that line in a scenario file which is set to the current date and launch Orbiter, you could fast forward in time to the 3rd of March. In theory, it will display the correct future position of the ISS on that date.

---------- Post added at 08:05 PM ---------- Previous post was at 02:06 PM ----------

For the best result, you should capture the ELEMENTS line shortly before the 3rd of March. I doesn't provide any rotation values, so you would need to set those yourselves.

 

[Donamy]

CMG would do that for you in game.

 

[Marijn]

CMG would do that for you in game.

Are you sure? Does CMG offer functionality to set the state vectors for the current position of the ISS? I don't know this add-on, but I don't read anything about that in the description so I think you misunderstood the question.

 

[Abdullah Radwan]

It doesn't provide any rotation values, so you would need to set those yourselves.

CMG provides rotation information.

 

[Marijn]

CMG provides rotation information.

The question was what the position is going to be of the ISS on the 3d of march 2019. That's 24 days into the future from this moment.

I never used CMG. But I find it unlikely that it will predict the position and rotation parameters. That would require an internet connection right? I don't read anything about that so I still think there is a miscommunication.

You can't get a precise predication further than 10 days into the future. If CMG can actually do this, it would convince me if you or someone else could post the RPOS, RPOS and AROT parameters here (or the ELEMENTS list). Let's take the 17th of March 12:00 GMT.

 

[Donamy]

There is [ame="https://www.orbithangar.com/searchid.php?ID=2617"]Scenario Editor TLE[/ame], for converting 2 element coordinates to Orbiter coordinates. Then you set the date in the scenario, run orbiter.

 

[Marijn]

There is Scenario Editor TLE, for converting 2 element coordinates to Orbiter coordinates. Then you set the date in the scenario, run orbiter.

Does it download the latest ISS data? Or do you need to feed the data in yourself?

I made the little app because I want to be able to set the actual ISS postion in a matter of seconds by copy pasting.

 

[Donamy]

You need to get the 2 element data first and put it into a folder that the Scenario editor can read. It takes more than a couple of seconds. You need to RTM.

 

[Marijn]

You need to get the 2 element data first and put it into a folder that the Scenario editor can read. It takes more than a couple of seconds

.
That's too much work. And tedious. That's why I made my own solution which allows copy pasting of a single block.

You need to RTM.

No idea why you say this. I have no interest in CMG.

---------- Post added at 04:19 PM ---------- Previous post was at 03:53 PM ----------

The reason why I left the rotation out is because I haven't been able to find a datasource which I could scrape. Of course, you can calculate the orientation under the assumption that the USA side is always facing forward and the pitch is 4 degrees below the horizon.

But I don't like assumptions. I want real data. If someone decides that the Russian side is going to face forwards from now on then I want my app to reflect that automatically.

So if someone knows a source of real ISS orientation data which I could use. That would be great.

 

[Donamy]

I'm not talking about CMG, just telling you how you can make a scenerio to launch the DM-1 to the station on 2/3/19.

 

[DaveS]

Of course, you can calculate the orientation under the assumption that the USA side is always facing forward and the pitch is 4 degrees below the horizon.

That's the standard attitude of the station. It's one of many so called Torque Equilibrium Attiudes (TEAs) that the station has available to it. The only visiting vehicles that requires the station to change its attitude is the Russian Soyuz and Progress.
Pre-STS-114 had the station always in the normal TEA but biased +20°s in the pitch axis to trim out the offset c.g the length of the orbiter caused.
Post-STS-114 saw this change with an added 180° yaw so that the upper surfaces faced the velocity vector. This was to protect the vulnerable bottom tiles and RCC from MMOD (let the more hardier blankets and windows take hits instead).

 

[Marijn]

That's interesting. Today I stumbled upon this 3D representation of the ISS: https://heavens-above.com/ISS_3D.aspx
Although the orientation looks ok to me, by inspecting the code, it seems that the -4 degrees pitch isn't modeled.

And while typing this comment, I found this site: http://www.telemetry.space/

It has the orientation . So I will add those to my app. Now I only have to work out the math to get the proper AROT..

The site labels the -4 degrees 'Yaw'. I don't understand that. Is the ISS not moving in the same direction as it's 'front-side'? Yaw means rudder to me, not pitch. Any idea?

---------- Post added 02-08-19 at 11:58 AM ---------- Previous post was 02-07-19 at 07:25 PM ----------

Hmmm. The information does not seem to get updated on this site http://www.telemetry.space/

 

[crisk73]

It would be interesting to see how Orbiter predictions about ISS position match DM1 launch window now listed as 07:48 UTC (02:48am EST) on March 2nd.

 

[Marijn]

It would be interesting to see how Orbiter predictions about ISS position match DM1 launch window now listed as 07:48 UTC (02:48am EST) on March 2nd.

Orbiter will do the job just fine. It all depends on the TLE you finally pick. The ISS could use it's thrusters occasionaly for various reasons. That will spoil the predications.

For the best resuts, you want to set the orbital elements of the ISS using the most recent TLE. In practice, I'd say you pick a TLE 12 hours prior to the DM1 launch.

My app behind the link above uses this data: https://api.wheretheiss.at/v1/satellites/25544/tles
I not sure whether that's the best one. I suspect it's being cached a bit long.

The best data source probably is: https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html

But I find this page rather complicated. I don't know which TLE set I should use. There are too many of them. Perhaps the CMG application does a better job by picking a better TLE from this page.

 

[crisk73]

The best data source probably is: https://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/orbit/ISS/SVPOST.html
But I find this page rather complicated. I don't know which TLE set I should use. There are too many of them.

The farthest prediction on that site is:

ISS
1 25544U 98067A 19053.70847448 .00016717 00000-0 10270-3 0 9164
2 25544 51.6407 210.4544 0005364 55.3856 304.7801 15.53299068 37466

Maybe it's worth picking this up.

 

[Marijn]

The farthest prediction on that site is: ...
Maybe it's worth picking this up.

Grabbing the last set of the page totally makes sense. But remember that it wasn't as straightforward as that. Not sure anymore though, It has been a while. I think the single TLE from the other site gave better results than the last one of the NASA site.

---------- Post added at 01:18 PM ---------- Previous post was at 01:06 PM ----------

Also, too judge whether the position of the ISS is accurate, you need to compare it with a value of which you know it's accurate. That's already problematic. I tried various sources on the web for that. But it's not always clear where those sources get their data from. Those sources might rely on the same data as well, or other data with flaws. I am not aware of a site which gives the ISS position 100% accurate.

So I am thinking of a plan to visually confirm it with my own eyes by setting up a scenario in which the ISS happens to be visible out of my window.

 

[crisk73]

Maybe it's pure chance but I've inserted the farthest prediction by NASA (Feb 22nd to date) and I've actualized data up to Mar 2nd 7:48 UTC and below is what I get.

Just in time to bring RInc close to zero. Cool.

 

[Marijn]

That seems to be a good result already. If you refresh the data shortly before the launch, it should get even more precise I think. What happens when you raise the periapsis? I think you should set it to the actual ISS altitude at the time of interception.

 

[CreponChris]

When I use the scenario editor in the default shuttle scenario called Launch into Sunrise to set the current date/time - the ISS position is totally different from what I get on any ISS tracking site online. I also know that the ISS in Orbiter 2016 is around 369 km orbital height. Can anyone point me to where I can find more info on how to correct the ISS orbital height and position? The google script link above doesn't seem current, or if it is when I transpose it (copy/paste) into scenario editor it doesn't seem to fix anything.

Edit: I'll be darned, the Scenario Editor TLS plugin is great. I don't really know as much as most folks here, but I'm hoping it corrected the ISS's orbital height to 418-420km or so. If anyone knows, please let me know. Also hope it's OK to bump older threads, here...