9
$\begingroup$

I'd like to find the state of the Apollo LM at various times during the powered descent phase: its position relative to the Moon's surface and/or the final touchdown point; its attitude in space, and its velocity vector.

At minimum I'd like this for Apollo 11 at 102:40:00 (5 minutes 40 seconds before touchdown); similar data for other missions and other references times would be great as well.

My goal is an interactive simulation of the last few minutes of the descent; I'm trying to get a sensible set of starting conditions for the sim.

From the Apollo 11 mission report I've gotten a pitch and lateral velocity for the time in question, but not the other data I'm looking for.

$\endgroup$
5
  • 4
    $\begingroup$ A subset of space.stackexchange.com/q/40074/6944 Where is that Volume II??! $\endgroup$ Jan 12, 2020 at 0:39
  • 5
    $\begingroup$ It turns out a former co-worker of mine might have worked on this reconstruction of the trajectory lroc.asu.edu/posts/1115 I've contacted him to find out if he can share the trajectory data. Will report back. $\endgroup$ Jan 12, 2020 at 0:49
  • $\begingroup$ Do you look for recorded LM landing radar data of distance and velocity? Was all radar data transmitted to mission control via telemetry and recorded in Houston? Data available only to the LM guidance computer is lost forever. $\endgroup$
    – Uwe
    Jan 13, 2020 at 10:52
  • $\begingroup$ @Uwe Position, attitude, and velocity was telemetered, and I’d be fine with interpolated data to cover any comm dropouts. $\endgroup$ Jan 13, 2020 at 17:09
  • $\begingroup$ how did it end up with the simulator? $\endgroup$
    – jumpjack
    Jan 23, 2022 at 6:42

1 Answer 1

7
$\begingroup$

I am working at a repository to collect all data about Apollo 11 powered descent (*):

https://github.com/jumpjack/Apollo11LEMdata

Data are "hidden" in several different documents; the only data I was able to find in tabular format are altitude data (in the infamous "volume 1"); for all others it's necessary to digitize available plots; most of the plots around are "beautified for the public", but I eventually found a document with precise plots such as this (I added the box with the document title and resource link):

vertical velocity plot

I also found this forum post listing all "Apollo experience reports" available on NTRS site, but beware that all links are broken due to server change; anyware the documents numbers are still valid.

For example, this link is invalid:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760019157_1976019157.pdf

You must convert it to:

https://ntrs.nasa.gov/api/citations/19760019157/downloads/19760019157.pdf

Other useful documents I found:

Some interesting documents, referenced in "APOLLO MISSION 11 TRAJECTORY RECONSTRUCTION AND POSTFLIGHT ANALYSIS - VOLUME 1" (1176-H508-R0-00 , N7024300, TRW note number 70-FMT-819), which I am not able to find:

  • Barnett, E.L., "Postflight Reconstruction of the Apollo 11 Descent Trajectory using HOPS Program", TRW IOC 5522.8-106, 5 nov 1969

  • Friedlander, M.M, "Preliminary Analysis of Apollo 11 Landing Radard Data", TRW IOC 5522.8-76, 15 aug 1969

  • Schiesser, E.L., "Apollo 11 Landing aite and LM Landing Position Determination", NASA/MSC memorandum 69-FM41-349, 30 oct 1969

The most difficult thing to find is fuels consumption of LEM DPS (Descent Propulsion System), I was only able to find this one:

descent fuel (DPS)

There are also available data on RCS (reaction Control System) but the very vertical line makes i very difficult to automatically digitize it, I heavily retouched the results., and additionally I don't get how the single chart matches with the separated chart.

RCS1

RCS2

Other acronyms and words useful for this search are:

  • DPS
  • Descent Propulsion System
  • DAP
  • Digital Auto Pilot
  • PDI
  • Powered Descent Insertion
  • DM
  • Descent Module
  • LM
  • Lunar Module
  • Postflight trajectory analysis
  • NAT
  • NASA Apollo Trajectory

Documents repositories:


(*) Apollo 11 mission had several different designations:

  • Apollo 11 (or Apollo XI)
  • AS-506 (Saturn V rocket)
  • CSM-107 (Command/Service Module 107)
  • CM-107 (Command Module 107)
  • LEM-5 (or LEM-05 or LM-5 or LM-05)
  • G-Mission (or "Mission G")

In some documents scans, "Apollo 11" became "Apollo II" and then finally "Apollo 2".

$\endgroup$
5
  • 3
    $\begingroup$ Thanks for the link to 'webplotdigitizer', that looks extremely useful. $\endgroup$ Jan 21, 2022 at 13:51
  • 1
    $\begingroup$ see also Aug 2022 NASA doc Reconstruction of the Apollo 11 Moon Landing Final Descent Trajectory NASA/TM–20220007267 $\endgroup$
    – Jason S
    Dec 26, 2023 at 5:15
  • $\begingroup$ @JasonS very cool, but are numerical data of the cleaned charts available? $\endgroup$
    – jumpjack
    Jan 4 at 18:30
  • $\begingroup$ I don't know of any numerical data, but I'd bet if you contacted one of the authors they would probably point you at anything available. $\endgroup$
    – Jason S
    Jan 5 at 19:35
  • $\begingroup$ I got into this subject because I was just curious how soft the lunar module landing was. Amazing that it turned into such a rabbit hole, and we don't have the basic data in an easily accessible form. :-( $\endgroup$
    – Jason S
    Jan 5 at 19:38

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.