Page 1 of 3 123 LastLast
Results 1 to 30 of 97

Thread: Some Apollo-Orion graphics that might be useful

Hybrid View

Previous Post Previous Post   Next Post Next Post
  1. #1
    Join Date
    Jul 2005
    Posts
    18,102

    Some Apollo-Orion graphics that might be useful

    I post this because it might be of interest, though it's not telling anyone here anything new, I'm sure.
    The recent Apollo "Hoax" thread reminded me of a(nother) fundamental misunderstanding that hoax believers have about the Van Allen Belts. They cite the high radiation dose encountered by the Orion EFT1 as if it indicates some sort of barrier that Apollo also had to pass through.
    So we explain that Orion was deliberately aimed into the high intensity region, while Apollo was routed to avoid it. The most common explanation I've seen offered is that the inclination of Orion's orbit was different from Apollo's, but I think the better explanation is one of apogee - Apollo's departure orbit was highly eccentric, with an (unperturbed) apogee out beside the moon, whereas Orion's apogee was tuned to lie in the inner VAB at about 5800km altitude.
    Since I had Celestia fired up for that other thread, with a depiction of a generic Apollo departure trajectory, I thought I'd set up a fictitious Orion EFT1 trajectory, too, with exactly the same inclination and perigee - the only difference between my generic Apollo and my fictitious Orion being the height of the apogee.
    And it turns out that's all it takes to demonstrate how different Orion and Apollo were.
    Here's an image (with a layout familiar to the folks who attended that other thread), looking towards the Earth from above the typical Apollo Trans-Lunar Injection location, the Pacific Ocean, with the typical orbital inclination around 30 degrees that results from the latitude of Cape Canaveral/Kennedy. At the time of TLI, the moon would be on the far side of the Earth from our viewpoint. The Earth's magnetic field is sketched in orange, with a couple of particle trajectories roughly depicting the inner VAB (the magnetic field and particle trajectories come from an add-on created by Celestia user Cham):
    Click image for larger version. 

Name:	Apollo-Orion1.png 
Views:	272 
Size:	454.3 KB 
ID:	23248
    And we point out to hoax believers that the tilt of the Earth's magnetic field, combined with the inclination of the departure trajectory, conspire to keep Apollo clear of all but the fringes of the VAB.

    If we look down on the orbital planes, we can see Apollo swinging wide, and my Orion depicted following a tighter ellipse superimposed on the inner VAB:
    Click image for larger version. 

Name:	Apollo-Orion2.png 
Views:	248 
Size:	492.6 KB 
ID:	23249

    And if we take a diagonal view, we can see how Apollo lofts clear of the VAB, while Orion dives right through the centre:
    Click image for larger version. 

Name:	Apollo-Orion3.png 
Views:	257 
Size:	456.8 KB 
ID:	23250

    Essentially, Orion's orbit has a node on the geomagnetic equator that lies within the VAB, so that it passes right through the high intensity region; whereas Apollo has a node that lies out near the moon somewhere, so it never encounters the core of the VAB.

    To that, we can add the factor of time. Because Apollo is near the perigee of a very eccentric orbit as it brushes the fringes of the VAB, it is moving quickly; whereas Orion passes through the core of the inner VAB at apogee, when it is moving most slowly.

    Again, I emphasis that my Apollo orbit is generic, and my Orion orbit resembles the real orbit only in terms of its approximate shape - but I think these images are a reasonably powerful way of pointing out why Orion can't be used to reason about Apollo.

    Grant Hutchison

  2. #2
    Join Date
    Mar 2003
    Posts
    3,032
    Agree, Grant. These are excellent depictions of the difference. Thank you for taking the time to create and present them.

  3. #3
    Join Date
    Aug 2005
    Location
    NEOTP Atlanta, GA
    Posts
    2,860
    For me the diagonal view is especially useful in visualizing how Apollo missions simply avoided most of the VAB. Why is such a simple concept so difficult to understand?

  4. #4
    Join Date
    Jan 2005
    Location
    Olympia, WA
    Posts
    30,964
    Because understanding it requires admitting you're wrong.
    _____________________________________________
    Gillian

    "Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"

    "You can't erase icing."

    "I can't believe it doesn't work! I found it on the internet, man!"

  5. #5
    Join Date
    Jun 2015
    Location
    Houston
    Posts
    1,216
    Great illustration, but still with a roughly circular LEO the Apollo TLI changes plane to allow for the new apogee along with avoiding the most intense portion of the VARB. Thanks
    Grant

  6. #6
    Join Date
    Oct 2017
    Posts
    447
    Quote Originally Posted by grant hutchison View Post
    I post this because it might be of interest, though it's not telling anyone here anything new, I'm sure.
    The recent Apollo "Hoax" thread reminded me of a(nother) fundamental misunderstanding that hoax believers have about the Van Allen Belts. They cite the high radiation dose encountered by the Orion EFT1 as if it indicates some sort of barrier that Apollo also had to pass through.
    So we explain that Orion was deliberately aimed into the high intensity region, while Apollo was routed to avoid it. The most common explanation I've seen offered is that the inclination of Orion's orbit was different from Apollo's, but I think the better explanation is one of apogee - Apollo's departure orbit was highly eccentric, with an (unperturbed) apogee out beside the moon, whereas Orion's apogee was tuned to lie in the inner VAB at about 5800km altitude.
    Since I had Celestia fired up for that other thread, with a depiction of a generic Apollo departure trajectory, I thought I'd set up a fictitious Orion EFT1 trajectory, too, with exactly the same inclination and perigee - the only difference between my generic Apollo and my fictitious Orion being the height of the apogee.
    And it turns out that's all it takes to demonstrate how different Orion and Apollo were.
    Here's an image (with a layout familiar to the folks who attended that other thread), looking towards the Earth from above the typical Apollo Trans-Lunar Injection location, the Pacific Ocean, with the typical orbital inclination around 30 degrees that results from the latitude of Cape Canaveral/Kennedy. At the time of TLI, the moon would be on the far side of the Earth from our viewpoint. The Earth's magnetic field is sketched in orange, with a couple of particle trajectories roughly depicting the inner VAB (the magnetic field and particle trajectories come from an add-on created by Celestia user Cham):
    Click image for larger version. 

Name:	Apollo-Orion1.png 
Views:	272 
Size:	454.3 KB 
ID:	23248
    And we point out to hoax believers that the tilt of the Earth's magnetic field, combined with the inclination of the departure trajectory, conspire to keep Apollo clear of all but the fringes of the VAB.

    If we look down on the orbital planes, we can see Apollo swinging wide, and my Orion depicted following a tighter ellipse superimposed on the inner VAB:
    Click image for larger version. 

Name:	Apollo-Orion2.png 
Views:	248 
Size:	492.6 KB 
ID:	23249

    And if we take a diagonal view, we can see how Apollo lofts clear of the VAB, while Orion dives right through the centre:
    Click image for larger version. 

Name:	Apollo-Orion3.png 
Views:	257 
Size:	456.8 KB 
ID:	23250

    Essentially, Orion's orbit has a node on the geomagnetic equator that lies within the VAB, so that it passes right through the high intensity region; whereas Apollo has a node that lies out near the moon somewhere, so it never encounters the core of the VAB.

    To that, we can add the factor of time. Because Apollo is near the perigee of a very eccentric orbit as it brushes the fringes of the VAB, it is moving quickly; whereas Orion passes through the core of the inner VAB at apogee, when it is moving most slowly.

    Again, I emphasis that my Apollo orbit is generic, and my Orion orbit resembles the real orbit only in terms of its approximate shape - but I think these images are a reasonably powerful way of pointing out why Orion can't be used to reason about Apollo.

    Grant Hutchison
    Sometimes I can't help myself. So you insist that Apollo's trajectory took it over the poles as depicted in your diagonal illustration? is the plane of that trajectory in the 30 degree plane to the earths equator?

  7. #7
    Join Date
    Jun 2015
    Location
    Houston
    Posts
    1,216
    Quote Originally Posted by TimFinch View Post
    Sometimes I can't help myself. So you insist that Apollo's trajectory took it over the poles as depicted in your diagonal illustration? is the plane of that trajectory in the 30 degree plane to the earths equator?
    Look at the first image, bypassing the More dense portions of the VARB, as you have been told. And no it wasn't over the north pole.

  8. #8
    Join Date
    Oct 2017
    Posts
    447
    Thank you for your timely response bknight but the question was for Grant Hutchinson.

  9. #9
    Join Date
    Jun 2015
    Location
    Houston
    Posts
    1,216
    Quote Originally Posted by TimFinch View Post
    Thank you for your timely response bknight but the question was for Grant Hutchinson.
    That's odd I didn't see it directed toward Grant, but none the less.

  10. #10
    Join Date
    Oct 2017
    Posts
    447
    Quote Originally Posted by bknight View Post
    That's odd I didn't see it directed toward Grant, but none the less.
    It was in response to his post and not yours but no harm no foul. I am seeking to understand Grant Hutchinson's intent.

  11. #11
    Join Date
    Jan 2005
    Location
    New Zealand
    Posts
    10,969
    Quote Originally Posted by TimFinch View Post
    Sometimes I can't help myself. So you insist that Apollo's trajectory took it over the poles as depicted in your diagonal illustration? is the plane of that trajectory in the 30 degree plane to the earths equator?
    Do you understand what's going on with perspective, when viewing that trajectory from different angles?

    Specifically:
    * When you wrote "over the poles", do you mean the left of these pictures, and do you think that actually shows something above the pole?
    * Do you now see that that's showing something that's not "over the poles" but actually far behind?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	timfinchspatialawareness.png 
Views:	147 
Size:	370.0 KB 
ID:	23257  
    Measure once, cut twice. Practice makes perfect.
    Why is a frog too?

  12. #12
    Join Date
    Oct 2004
    Location
    Perthshire, UK
    Posts
    223
    Quote Originally Posted by TimFinch View Post
    Sometimes I can't help myself. So you insist that Apollo's trajectory took it over the poles as depicted in your diagonal illustration? is the plane of that trajectory in the 30 degree plane to the earths equator?
    Hang on Tim... You've been banging on for ages about how 2D representations are so much better than 3D models, and now you're complaining that you can't understand the different perspectives Grant has taken the trouble to produce?

    Perhaps you should take a more considered look at the diagrams and properly appreciate what they're showing about the three-dimensional nature of reality...
    Days spent at sea are not deducted from one's alloted span...
    (Phoenician proverb)

  13. #13
    Join Date
    Oct 2017
    Posts
    447
    Quote Originally Posted by molesworth View Post
    Hang on Tim... You've been banging on for ages about how 2D representations are so much better than 3D models, and now you're complaining that you can't understand the different perspectives Grant has taken the trouble to produce?

    Perhaps you should take a more considered look at the diagrams and properly appreciate what they're showing about the three-dimensional nature of reality...
    I haven't complained at all. I simply asked a question to the poster and I await his response. You can read whatever you like into this but it is no more than a single question to clarify my understanding. Why is this complicated or a problem?

  14. #14
    Join Date
    Oct 2004
    Location
    Perthshire, UK
    Posts
    223
    Quote Originally Posted by TimFinch View Post
    I haven't complained at all. I simply asked a question to the poster and I await his response. You can read whatever you like into this but it is no more than a single question to clarify my understanding. Why is this complicated or a problem?
    It's a problem for you in that you seem to be the only person looking at Grant's diagram and not understanding the perspective view. My initial comment was highlighting that you have repeatedly claimed that 2D representations are much better, yet you seem unable to see that none of Grant's diagrams show the flight path as being over the pole...
    Days spent at sea are not deducted from one's alloted span...
    (Phoenician proverb)

  15. #15
    Join Date
    Apr 2018
    Location
    United Kingdom
    Posts
    43
    Grant, these are superb images once more. The 3 perspectives compile beautifully to understand the 3 spherical coordinates at play. Thanks for posting, and once more saved to my hard drive.
    Last edited by Baron Greenback; 2018-Apr-28 at 06:50 PM.

  16. #16
    Join Date
    Feb 2006
    Posts
    544
    Grant,

    Would you mind posting the SSCs that you used for the trajectories?
    Selden

  17. #17
    Join Date
    Jul 2005
    Posts
    18,102
    Quote Originally Posted by selden View Post
    Grant,

    Would you mind posting the SSCs that you used for the trajectories?
    In case anyone's fretting about this, I emailed selden the necessary file.

    Grant Hutchison

  18. #18
    Join Date
    Apr 2018
    Posts
    3
    Had a look as well and seems pretty obvious that the trajectories are not passing over the poles.

  19. #19
    Join Date
    Oct 2017
    Posts
    447
    So am I to understand a specific question to an individual does not have to be responded to and the poster can ignore the question? Is that the way it works today because it was different yesterday?

  20. #20
    Join Date
    Jun 2003
    Posts
    1,729
    Quote Originally Posted by TimFinch View Post
    So am I to understand a specific question to an individual does not have to be responded to and the poster can ignore the question? Is that the way it works today because it was different yesterday?
    For someone who has just accused others of 'judging beyond the question' you do like to leap to your own conclusions, don't you? How do you know that Grant has even been on and seen your question yet? You posed it some hours after he put up the initial drawings. Why conclude he is ignoring you?

    And as this is a forum with many members, no, you don't get to decide who responds to your posts, and you don't get to decalre the responses invalid because of who they come from.

    Once again, your spatial recognition skills are either stupendously bad, or you are just getting your kicks. As you're back, how about heading over to your other thread and dealing with the outstanding questions there?

  21. #21
    Join Date
    Oct 2017
    Posts
    447
    Quote Originally Posted by Jason Thompson View Post
    For someone who has just accused others of 'judging beyond the question' you do like to leap to your own conclusions, don't you? How do you know that Grant has even been on and seen your question yet? You posed it some hours after he put up the initial drawings. Why conclude he is ignoring you?

    And as this is a forum with many members, no, you don't get to decide who responds to your posts, and you don't get to decalre the responses invalid because of who they come from.

    Once again, your spatial recognition skills are either stupendously bad, or you are just getting your kicks. As you're back, how about heading over to your other thread and dealing with the outstanding questions there?
    I have not accused him of such. I have said that I patiently awaited his response. I was asking why I was pressured to accept responses from other than the poster when it was a specific question to a specific poster in regard to his post. Why everyone feels they can speak for the poster is interesting at many levels.

  22. #22
    Join Date
    Jul 2010
    Posts
    202
    Quote Originally Posted by TimFinch View Post
    Why everyone feels they can speak for the poster is interesting at many levels.
    No it is not. You make a ridiculous statement that everyone else can see and those who can be bothered with it choose to attempt to educate you! It doesn't require Grant to answer when the claim is so obviously wrong to everyone else.

  23. #23
    Join Date
    Oct 2017
    Posts
    447
    Quote Originally Posted by Clanger View Post
    No it is not. You make a ridiculous statement that everyone else can see and those who can be bothered with it choose to attempt to educate you! It doesn't require Grant to answer when the claim is so obviously wrong to everyone else.
    So because you saw a question directed at someone else you feel an intrinsic need to respond? Do you answer other people's phone because they were ringing?

  24. #24
    Join Date
    Oct 2012
    Posts
    31
    You also need to bear in mind that people are not at your beck and call, nor are they necessarily in your time zone, and believe it or not might actually have better things to do than explain the self-explanatory to someone who doesn't want to listen.

  25. #25
    Join Date
    Jun 2004
    Posts
    1,675
    Here's a hypothesis (I utterly lack the mathematical background to investigate it, much less proof it). Take a plane. Draw a geometric figure on it; say an ellipse. From any point on that plane the figure will appear as a line. Add a second plane, with a geometric figure drawn on it. There exists one single point, looking along the intersection of those planes, where both figures will appear as lines.

    Now add a third plane, with included geometric figure. There exists no point, no view, in which all three figures appear as a line.

    Since we are considering the plane of the low-earth orbit, the plane of lunar injection orbit post TL1, the plane of the equator, the plane of the geomagnetic equator, and (for no good reason) the plane of the lunar orbit, it seems clear that no 2d representation will preserve all the relative positions of objects on those planes.

  26. #26
    Join Date
    Mar 2007
    Location
    Falls Church, VA (near Washington, DC)
    Posts
    8,816
    Grant gave us a clear mathematical analysis of the radiation dose in post 168 in the other thread, and his posting of the orbital illustrations in three different viewing angles in this thread reinforces my confidence in what he said. All I have seen from Tim Finch in numerous posts since then is what I would consider smokeblowing. Even before then I could not see a coherent presentation that would show an unacceptable exposure to radiation. When he started asserting that a rocket is necessary to keep a spacecraft in orbit, and that the need for a midcourse correction was caused by the increasing dominance of the Moon's gravity during the latter part of the outbound journey, any perception that he had any credibility vanished into cyberspace.

    Let me add that it is about 10:45 PM at Grant's home in the UK, so I would not be quick to assume that he must be reading these threads right now.

  27. #27
    Join Date
    Sep 2003
    Location
    The beautiful north coast (Ohio)
    Posts
    49,261
    Might I suggest we ignore TimFinch's hijacking of this thread and his questions (he certainly is not going to be answering them any time soon) and go back to the original intent of this thread; of collecting useful diagrams and visuals of the missions.

    This is just a suggestion - if he wish to chase after TimFinch's idea... have fun.
    At night the stars put on a show for free (Carole King)

    All moderation in purple - The rules

  28. #28
    Join Date
    Jul 2005
    Posts
    18,102
    I thought I told you guys to just play quietly and keep the house tidy while I was out? Sheesh.


    Yes, everyone but TimFinch understood correctly that the Apollo transfer orbit goes nowhere near the poles. The first two images make that pretty clear, I thought.

    For reference, here's another image with my lunar orbit marked in blue, showing that (as people have pointed out) the transfer orbit is not in the same plane as the lunar orbit.
    Click image for larger version. 

Name:	Apollo-Orion4.png 
Views:	206 
Size:	351.8 KB 
ID:	23261

    My model doesn't include a plane change at TLI. I wanted to cut things down to the bare minimum that showed the important detail - so EPO is a circular orbit corresponding to a direct eastward launch from the Cape, the Apollo transfer orbit is in the same plane as EPO, as is the Orion orbit, and the Moon is sitting in the ecliptic plane to make the sums easier. I also haven't included the perigee lowering that was carried out for ETF1, which actually had a perigee within the Earth during its second orbit, to test high-speed re-entry.
    With a bit of work I could add these details, but I think they would complicate things without improving the explanatory power - In contrast to the usual use of Celestia I'm just trying to draw a good diagram, rather than create a realistic depiction.

    Grant Hutchison

  29. #29
    Join Date
    Jun 2015
    Location
    Houston
    Posts
    1,216
    Grant you did good, very nice spherical illustrations of what we have been discussing

  30. #30
    Join Date
    Jan 2008
    Posts
    731
    Quote Originally Posted by grant hutchison View Post
    I thought I told you guys to just play quietly and keep the house tidy while I was out? Sheesh.


    Yes, everyone but TimFinch understood correctly that the Apollo transfer orbit goes nowhere near the poles. The first two images make that pretty clear, I thought.

    For reference, here's another image with my lunar orbit marked in blue, showing that (as people have pointed out) the transfer orbit is not in the same plane as the lunar orbit.
    Click image for larger version. 

Name:	Apollo-Orion4.png 
Views:	206 
Size:	351.8 KB 
ID:	23261

    My model doesn't include a plane change at TLI. I wanted to cut things down to the bare minimum that showed the important detail - so EPO is a circular orbit corresponding to a direct eastward launch from the Cape, the Apollo transfer orbit is in the same plane as EPO, as is the Orion orbit, and the Moon is sitting in the ecliptic plane to make the sums easier. I also haven't included the perigee lowering that was carried out for ETF1, which actually had a perigee within the Earth during its second orbit, to test high-speed re-entry.
    With a bit of work I could add these details, but I think they would complicate things without improving the explanatory power - In contrast to the usual use of Celestia I'm just trying to draw a good diagram, rather than create a realistic depiction.

    Grant Hutchison
    And IMHO you did a damn fine job. Well done.

    I simply cannot fathom why anyone cannot understand the clear illustrations.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •