I am trying to get the state vectors for Apollo 15 before, during, and after critical manoevers [sp]. IE TLI, LOI1, LOI2, lunar launch, preocking, postdocking, and TEI.

I am a totally newbie at all this. My experience comes from using the space flight simulator Orbiter.

My goal is to use the Apollo 15 Virtual AGC version of the spacecraft in the simulation to accurately portray the mission using the AGC computer and inputting the state vectors; any guidance on how to obtain these state vectors is appreciated.

  • $\begingroup$ Hi Tex, I made some small edits to your question and added some tags, have a look to double check and feel free to edit further. Welcome to Space! $\endgroup$ – uhoh May 27 '19 at 17:47
  • $\begingroup$ Thanks. There is a document in the National Archives but finding it is like looking for The Ark of the Covenant. The Virtual AGC website has some documentation links I have gone through regarding the Archives. Unfortunately they need box and shelf information due to the quantity of material saved. The other Avenue is to generate the vectors from Adammo (sp) website about Reconstruction of Apollo 13 flight using existing NAT elements and converting to xyz elements, earth or moon centered. It's a long road no matter the choice. The state victors were called up, radio transmitted. $\endgroup$ – Tex May 28 '19 at 19:34
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    $\begingroup$ Wow, it sounds like you've put quite a lot of work into this already! What are "existing NAT elements"? $\endgroup$ – uhoh May 28 '19 at 23:28
  • $\begingroup$ Apollo form of orbital elements. I need to find a document for you to look at to get it. But suffice to say it's not simple x y z Vx Vy Vz. Has some ecliptic and other info. $\endgroup$ – Tex May 30 '19 at 2:50

There are multiple ways to approach this question. You could take the trajectory parameters from this postflight document. It doesn't have a full set of orbital parameters for all the cases you are looking for, but it is some actual tracking data which would have been uplinked to the AGC.

Then, as you are familiar with Orbiter, you probably know about the project I am working on. I am one of the developers of NASSP, an addon for Orbiter that simulates the Apollo program and that has implemented the Virtual AGC. You can fly full missions with NASSP that are using the Virtual AGC. So that would give you several options, none of which will give you the exact trajectory or state vectors in the AGC from Apollo 15, but pretty close nevertheless:

  • Fly Apollo 15 with NASSP yourself.
  • Get someone (like me) to generate Virtual AGC core files (complete erasable memory dumps, not just the state vectors) for the specific points you want to have. These core files can be loaded in the standalone Virtual AGC application and will then give you the complete state of the AGC at the times you want. I have flown Apollo 15 in NASSP and so have some other people, so we wouldn't have to fly the whole mission again to do this, just load up some old save files and generate the core files.
  • Get someone (like me) to do all of the things above, but just for the state vectors. State vectors alone won't get you all that far with the Virtual AGC though, there is a lot more to making it usable than that.

This goes a bit beyond a simple question/answer so you could make a post in our forum to discuss more details of what you want to achieve.

Here an example core file for the Virtual AGC, it's an Apollo 15 pre LOI file and has everything the CMC had loaded at that point. State vectors and many other things. This will be very close to the state of the CMC during the actual Apollo 15 mission.

  • $\begingroup$ Thanks. I haven't used NASSP Orbiter in a while. I was hoping it was now at a point where the called up state vectors, Verb 71, could be keyed in and be put at that point in time at that xyz place. The simulator documentation gives this info, so I figured I could get A15 sim data and go from there. $\endgroup$ – Tex May 30 '19 at 2:45
  • $\begingroup$ The Virtual AGC is fully implemented in NASSP now, in both CSM and LM. Uplinks are generated mostly automatically, the state vectors are from the Orbiter API and are then converted to the right coordinate system for the AGC. This document describes the uplink format: ibiblio.org/apollo/Documents/HSI-208452.pdf So would it be helpful for you if I gave you some state vectors in the V71 format? As I said before, the state vectors wouldl be close to the actual mission, but not exactly like it. $\endgroup$ – indy91 May 30 '19 at 8:54
  • $\begingroup$ Thank you very much Indy91. To take time out of your life help me get to where i want to go is nice. Before you go through all that effort, i was going to get the A15 simulator package and other documents from the national archives in Ft. Worth TX. Im trying not to lean too hard on the NASSP team for info out of respect for their and your's time. One question I had was whether the Artemis is loaded with the preliminary PAD data. It must be important if they had it. And if you ran the standalone Virtual AGC in time sync with the Apollo NASSP side by side whether the same data comes out. $\endgroup$ – Tex May 31 '19 at 16:32
  • $\begingroup$ Out of curiosity, what document had you planned to request from NARA? "Apollo 15 Operational Trajectory Simulator Data Package (MSC memo 71-FM-141)" would probably be what you are looking for, that document is available for Apollo 10 online. Requesting these documents from NARA can be quite expensive though. In the launch scenario for Apollo 15 in NASSP the padload is indeed loaded, if that is what you mean. And you can't run the standalone Virtual AGC with NASSP, only the build-in Virtual AGC version. I can send you a core file saved in NASSP for the standalone Virtual AGC. $\endgroup$ – indy91 May 31 '19 at 17:15
  • $\begingroup$ I amended the original answer with an example core file for you to try with the standalone Virtual AGC. Very easy to generate for me, so if it works for you I can create more of them. $\endgroup$ – indy91 May 31 '19 at 17:27

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