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The last few images in Robert A. Braeunig's Apollo 11's Translunar Trajectory; and how they avoided the heart of the radiation belts are fascinating and a bit perplexing as discussed in this answer and the comments below it.

This got me wondering what it would take to reconstruct the trajectories of one or more of the Apollo missions from scratch.

  • only the crewed components that NASA tracked carefully because there were people on board
  • primarily outside of Earth's atmosphere where I can numerically integrate trajectories without aerodynamics

Are there raw data out there somewhere? Perhaps range-rate, Doppler etc.? I'm assuming these were recorded and analyzed post mission and written up post-mission, with some tables, but are there large tables of state vectors? Is the raw data available somehow?

Question: If I wanted to reconstruct an entire Apollo mission's crewed spacecraft trajectories, what are the key sources of historical data I'd look for? Where might I find some of them?

There may be some promising leads in answers to Where to look for historical or reconstructed orbit data for early NASA missions - Mercury-Atlas 6 for example. Maybe some day we can get the final answer to Puzzler: Precisely what maximum distance from the Earth did the Apollo 13 astronauts achieve?

uhoh
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3 Answers3

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To answer the question literally: you'd be looking for NASA Apollo Trajectory (NAT) data files.

The report Apollo Mission 11, Trajectory Reconstruction and Postflight Analysis Volume 1 (PDF) provides a summary for Apollo 11 and mentions that the raw NAT data is available in Volume 2 of the report. I have yet to find Volume 2 though, perhaps because

The listing is not generally distributed but is available from NASA/MSC upon request.

Also Earth Departure Trajectory Reconstruction of Apollo Program Components Undergoing Disposal in Interplanetary Space mentions the availability of NAT data, but without reference.

I requested the document at NASA STI, but:

Thank you for contacting the NASA STI Information Desk. Unfortunately, we do not have the requested document in our repository.

So I asked the author of the paper where to find them. I was thinking about huge data files, but turns out that the available NAT data is a single table that can be found in the Mission Reports. For example, for Apollo 11, it's table 7-II in the Apollo 11 Mission Report.

Trajectory parameters for Apollo 11

(Trajectory parameters for Apollo 11 from Apollo 11 Mission Report)

For Apollo 17, I found "Apollo/Saturn 5 postflight trajectory: AS-512" on NTRS, which contains a wealth of information. Similar documents likely exist for the other Apollo missions, but I have not yet been able to locate them.

Ludo
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    I submitted an inquiry regarding the availability of volume II, see what comes from that. – Ludo Nov 24 '19 at 16:01
  • I don't believe that Apollo Mission 11, Trajectory Reconstruction and Postflight Analysis *Volume 2* in toto is just Table 7-II in another report. It could be that Volume 2 is lost or unavailable due to something like this. But if Volume 1 is 142 pages long, it's hard to believe Volume 2 would be only a single page. However the points in the table certainly appear to be extremely helpful for trajectory reconstruction. Thanks! – uhoh Dec 01 '19 at 04:32
  • fyi I've just asked What (the heck) are "space-fixed coordinates" as described in Apollo mission trajectory analyses? and also What do these Apollo era terms mean? – uhoh Dec 01 '19 at 04:49
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    @uhoh I believe that Volume II also contained Best Estimate Trajectories (BET), which I presume to be interpolated data from these tables (i.e. exactly what the reconstruction paper did and what we're trying to do here). Those BET might have been the bulk of Volume II. Given the existence of the Reconstruction paper, Volume II may indeed be lost. – Ludo Dec 01 '19 at 08:26
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    @Ludo I've found similar trajectory reconstruction report Vol.I for Apollo-8: https://www.ibiblio.org/apollo/Documents/19740072902.pdf Same story with Vol.II though (listing in NAT format "available" at request at NASA/MCS Computations and Analysis Division). Vol.I contains some data on what I think is estimated orbital parameters, but not 100% sure. – Sergiy Lenzion Jan 16 '20 at 13:41
  • I have good news and bad news. Good news is that I found a document with plenty of plots and data about apollo 11 LM-05 powered descent: https://github.com/jumpjack/Apollo11LEMdata/blob/master/apollo11-charts.png

    The bad news is that, as I found them after looking in dozens of documents, I lost the references to the source of these plots, because I copied the charts while viewing the document online, without saving...

     – jumpjack Jan 18 '22 at 12:25
  • @jumpjack Those seem to be only the LEM descent from Lunar orbit to Lunar surface. The OP is interested in the entire trajectory, so from launch to splashdown. – Ludo Jan 18 '22 at 15:20
  • https://ntrs.nasa.gov/ – jumpjack Jan 18 '22 at 22:01
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Found Saturn V full trajectory numerical data in tabular format: Report No. 61291 - AS-506 "G" MANNED LUNAR LANDING MISSION POST-LAUNCH OPERATIONAL TRAJECTORY FOR JULY 16, 1969

Other full tables with numerical data for trajectories of all stages, up to CSM separation at 11723s:

Document D5-15560-6 - APOLLO/SATURN V POSTFLIGHT TRAJECTORY - AS-506

Further data:

SATURN V LAUNCH VEHICLE FLIGHT EVALUATION REPORT-AS-506 - APOLLO 11 MISSION (MPR-SAT-FE-69-9 , N90-70431

Samples from report 61291:

cover page

Introduction

Index of tables

Sample 1

Sample 2

Table list from DS-15560-6:

tables list

Trajectory key points:

key points

Table example:

table example

jumpjack
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    While this is not the "entire" trajectory, this is still an absolutely amazing find! How did you find it? Did you find similar reports for other missions? I'm also really curious to see how well this the "reconstruction paper" (mentioned in the other answer) and other simulations like Braeunig's match up with this – Ludo Jan 23 '22 at 18:57
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    six missions are too many, given that there are hundreds of documents for each one, so I am focusing on apollo 11. – jumpjack Jan 23 '22 at 20:09
  • @Ludo about your question: I am setting up a web page to retrieve all search results from http://ntrs.nasa.gov as a single table of some thousands of lines rather than hundreds of pages to be downloaded one by one. You'll find the page in my repo once it's ready: https://github.com/jumpjack/Apollo11LEMdata – jumpjack Jan 23 '22 at 22:09
  • Added another resource: Document D5-15560-6 - APOLLO/SATURN V POSTFLIGHT TRAJECTORY - AS-506 - http://www.ibiblio.org/apollo/Documents/19920075301.pdf – jumpjack Jan 24 '22 at 09:50
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I found a method to directly plot the full trajectory of S-IVB (NASA id: -399110) from launch to CSM separation and beyond, being data available on NASA Horizon server:

Full trajectory w.r.t. Earth:

full trajectory w.r.t. Earth

Full trajectory w.r.t Moon:

Full trajectory w.r.t Moon

Unfortunately there are no data for CSM and LM of Apollo 11, but there are for Apollo 10, I write them here below separately.

Apollo 10 data

I don't put images here, not to mess up with the answer, but you've just to replace the orbiter parameter in the url:

  • orbiter=-399110 --> orbiter=-399100 (Apollo 10 S-IVB)
  • orbiter=-399110 --> orbiter=-399101 (Apollo 10 LM)

Note: in case of "network error", remove "s" from "https" in the url.

Apollo 10 S-IVB Timeline:

  • Apollo 10 S-IVB / CSM separation: 1969-MAY-23 19:51:42
  • Descent orbit insertion ignition - 20:35:01 22-May-69
  • LM closest approach to lunar surface - 21:30:43 22-May-69
  • LM separation maneuver ignition 05:32:23 23-May-69
  • LM ascent propulsion system ignition 05:41:05 23-May-69 <<<---- LM ephemeris available from here
  • LM ascent propulsion system depletion 05:45:14 23-May-69

See here for a full list of available spacecrafts: https://ssd.jpl.nasa.gov/horizons_batch.cgi?batch=1&COMMAND=%27*%27

jumpjack
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  • This is excellent news! It seems that it's been there since at least 2016, before I'd asked the question. – uhoh Mar 02 '22 at 11:56
  • @uhoh Note that when you query Horizons directly, it says (e.g. for A10): "The trajectory here is a reconstruction of the Apollo 10 Lunar Module ascent stage ("Snoopy") departure trajectory developed by Daniel R. Adamo under contract to NASA in 2012. " This is not original data! – Ludo Feb 29 '24 at 13:40
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    @Ludo Yes that's right. I was surprised that this reconstruction was there and I didn't know about it, and I think it would be helpful to compare one's own reconstruction with this one, but indeed it is not a "key source of historical data". – uhoh Feb 29 '24 at 20:08
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    @ludo You will always read "reconstruction" for every mission, also recent. Raw data are just IMU data, star tracker data, observations,.... Reconstructing missions trajectory is an hard work, spice kernels always mention papers used to reconstruct the data, and I think Horizons gets data from such kernels. – jumpjack Mar 01 '24 at 08:52
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    @jumpjack absolutely true. The difference here being that this reconstruction was done about 40 years after the mission based on incomplete data archives, so I just wanted that to be clear. But you are right of course. – Ludo Mar 01 '24 at 09:40