Apollo 11 6 hour P23
- Thread starter Kram45
- Start date
That should be noted in the flightplan. Without taking a look at it: when you are this close to earth, almost all marks will be done as "earth near horizon", i.e. 00110 in R3 of V70.
V70 is structured like this:
000XX - star code
00X00 - landmark code
00XX0 - horizon code
This is all octal, i.e. no + or - and leading 0's can be omitted. The star code is self-explanatory, landmark can be 0 (no landmark), 1 (earth landmark) or 2 (moon landmark). The first digit of the horizon code is analog to landmark: 0 for no horizon, 1 for earth horizon, 2 for lunar horizon. The second digit denotes whether the near horizon (1) is used or the far horizon (2). Note that for horizon sightings, R2 has to be 0 and R3 should contain something useful; for landmark sightings it's the other way round (although the program should look at R2 first and ignore the data in R3; however, if the manual says so...
)
V70 is structured like this:
000XX - star code
00X00 - landmark code
00XX0 - horizon code
This is all octal, i.e. no + or - and leading 0's can be omitted. The star code is self-explanatory, landmark can be 0 (no landmark), 1 (earth landmark) or 2 (moon landmark). The first digit of the horizon code is analog to landmark: 0 for no horizon, 1 for earth horizon, 2 for lunar horizon. The second digit denotes whether the near horizon (1) is used or the far horizon (2). Note that for horizon sightings, R2 has to be 0 and R3 should contain something useful; for landmark sightings it's the other way round (although the program should look at R2 first and ignore the data in R3; however, if the manual says so...
)
polaris149Tiberius
Tutorial Publisher
Hey MrFeckles. I couldn't find which stars were planned in the Flight Plan. Can you send a link to which flight plan your using (as I believe I have found 2 versions) and reference either the PDF page number or the document's page number. Also, does ENH stand for Earth Near Horizon? If so is EFH a typo or what does it mean in your reply? Also what is SV? Thanks in advance.
rcflyinghokie
LM Junky
Hey I can help answer some of these:
Here is a quality scan of 11's flight plan, you can see at the 6 hour mark (flight plan page 3-7) the stars used. https://www.ibiblio.org/apollo/Documents/Apollo_11_Flight_Plan_HSK.pdf
Additionally, ENH is "earth near horizon" and EFH is "earth far horizon." SV is "state vector."
What also might help answer some questions for Apollo 11 is the operations checklist, which among other things has the P23 procedures. https://www.ibiblio.org/apollo/Documents/Apollo11_Checklist_CSM107.pdf
polaris149Tiberius
Tutorial Publisher
Man rcflyinghokie, thank you sooooo much for all your help.
I dont see the attitudes they needed to change to in the Flight Plan.
I am now currently looking for the P23 OpticsCal attitude(s) (Roll: xxx.x, Pitch: xxx.x, Yaw: xxx.x), Collins was changing to for star Enif (44)(RA 21 44 11.2 Dec +09 52 30) at about GET 006:20:37 as part of an attitude change that caused a gimbal lock warning discussed on Realtime (https://apolloinrealtime.org/11/?t=006:20:28&ch=14)
Did they need one attitude for the different stars of P23 or did they turn to several attitudes or a new attitude for each of the stars listed above and below:
The P23 at 6h GET was planned to be:
star 02 ENH Diphda
star 40 EFH Altair
star 44 ENH x2 Enif
star 45 ENH Fomalhaut
Thanks in advance!
I dont see the attitudes they needed to change to in the Flight Plan.
I am now currently looking for the P23 OpticsCal attitude(s) (Roll: xxx.x, Pitch: xxx.x, Yaw: xxx.x), Collins was changing to for star Enif (44)(RA 21 44 11.2 Dec +09 52 30) at about GET 006:20:37 as part of an attitude change that caused a gimbal lock warning discussed on Realtime (https://apolloinrealtime.org/11/?t=006:20:28&ch=14)
Did they need one attitude for the different stars of P23 or did they turn to several attitudes or a new attitude for each of the stars listed above and below:
The P23 at 6h GET was planned to be:
star 02 ENH Diphda
star 40 EFH Altair
star 44 ENH x2 Enif
star 45 ENH Fomalhaut
Thanks in advance!
Last edited:
rcflyinghokie
LM Junky
P23 generates an initial attitude for each star
polaris149Tiberius
Tutorial Publisher
Thank You!! I wish there was a list of the attitudes that they did with the stars and at what times. Thanks for your amazing help sir.
rcflyinghokie
LM Junky
For Apollo 11, they relied on P23 to get the initial attitudes generally, you can also get some of the adjusted ones from the transcript as you have seen.
However the mission reports have a list of all alignments and such.
polaris149Tiberius
Tutorial Publisher
A thousand thank you's kind sir!!
