Suspect DAC Footage - Part 2 Apollo 11-12 LM Rendezvous

[jfb]

The orientation of the CSM relative to the lunar surface changes throughout the clip.  At the beginning of the clip it is pointing almost straight down towards the surface; as the LM approaches, the CSM's orientation relative to the Lunar surface changes (it stays pointing the same direction in space, so as it orbits the Moon the nose starts pointing more towards the horizon).  I've attached a very crude drawing illustrating this.

Nice work. And here's a drawing I did some years ago illustrating the same thing for someone who couldn't figure out how the shadows changed, how the time for things to cross the image changed, or how the LM remained in one place in the view. It shows how the amount of lunar surface captured in the field of view increases as i gets closer to the limb, how the two spacecraft remain in the same relative line of sight, how the spacecraft do not change their orientation, and how it goes from looking straight down onto the surface to looking into space.



JR, you just cannot compare orbiting bodies to aircraft in the way you want to. Do you, for example, understand that neither of the two spacecraft in that footage are actually under powered flight at that point in the mission?

Well that puts my sad little PPT slide all to shame, and illustrates far better what is happening. 

One of the weird things I noticed playing with an early version of KSP is how my little spacecraft kept the same orientation in space as they orbited.  At the time it surprised me because I was used to how spacecraft flew in science fiction - that is, like airplanes.  The more I think about it, though, the more sense it makes, as there's nothing exerting a torque on the spacecraft to turn it in the direction of motion.  For small spacecraft (and the CSM counts), the difference in gravitational attraction from one end to the other is too small to have much influence. 

So I'm assuming that for comm and spy sats that continually have to be pointing towards the surface, you have to apply a momentary torque (either through a thruster or reaction wheel?) to get it to spin, and make sure it's spinning at a rate such that it completes one rotation per orbit. 

[JayUtah]

So I'm assuming that for comm and spy sats that continually have to be pointing towards the surface, you have to apply a momentary torque (either through a thruster or reaction wheel?) to get it to spin, and make sure it's spinning at a rate such that it completes one rotation per orbit.

Yes.  Some communications spacecraft have extremely tight pointing constraints because their beams have to hit not just the planet, but a specific small area -- and only a specific small area -- of the planet.  Recon satellites don't have to be geostationary, but they can often be in geosynchronous orbits, sometimes with very low perigees.  The shape of the orbit differs with the mission.  But the overriding point is, as you say, that the orientation of the spacecraft and its orbital path are not physically coupled until you start talking about tidal forces.  A spacecraft in orbit can maintain its same orientation relative to the planetary surface only by specifically arranging for that to happen.

[molesworth]

One of the weird things I noticed playing with an early version of KSP is how my little spacecraft kept the same orientation in space as they orbited.  At the time it surprised me because I was used to how spacecraft flew in science fiction - that is, like airplanes.  The more I think about it, though, the more sense it makes, as there's nothing exerting a torque on the spacecraft to turn it in the direction of motion.  For small spacecraft (and the CSM counts), the difference in gravitational attraction from one end to the other is too small to have much influence.

This, I think, is one of the things which is confusing JRK - spacecraft don't fly like aircraft, don't stop dead when the engines turn off, and don't need to bank when turning.

Science fiction TV and movies have played into the "aircraft-like" trope for many years, and influenced expectations.  Except perhaps for Babylon 5's Star Furies, which I believe were admired for their control systems by some NASA engineers 

[smartcooky]

One of the weird things I noticed playing with an early version of KSP is how my little spacecraft kept the same orientation in space as they orbited.  At the time it surprised me because I was used to how spacecraft flew in science fiction - that is, like airplanes.  The more I think about it, though, the more sense it makes, as there's nothing exerting a torque on the spacecraft to turn it in the direction of motion.  For small spacecraft (and the CSM counts), the difference in gravitational attraction from one end to the other is too small to have much influence.

This, I think, is one of the things which is confusing JRK - spacecraft don't fly like aircraft, don't stop dead when the engines turn off, and don't need to bank when turning.

Science fiction TV and movies have played into the "aircraft-like" trope for many years, and influenced expectations.  Except perhaps for Babylon 5's Star Furies, which I believe were admired for their control systems by some NASA engineers 

and BSG 2002's Vipers.

[jr Knowing]

HI JFB and Jason Thompson, Bknight, Molesworth, OBM et al

I appreciate your responses to my claims (and Jay, I do believe I am attempting to reciprocate, albeit I don't have enough time in the day to respond to everyone.

First, BKnight, the distance is more than 3600 feet between the LM and CSM. The communication you quote is the first dialogue when they come around from the far side of the moon. The A11 clip is 20 minutes in real time. It took 55 minutes for the LM to transition from its lunar orbit to the CSM's lunar orbit approximately 12-14 miles higher. Clearly that points to a greater separation between the LM and CSM at the start of the clip than you are suggesting.

JFB and Jason Thompson, your suppositions actually help my case. Jason, even if one agrees to your plotting of the LM relative to the CSM and the range of view from the CM window (both which I take exception to), you (and JFB) seem to ignore the fact of how this was filmed. It was was filmed into a mirror. More specifically a right angle mirror. First off the use of a 1.5 inch mirror will greatly curtail the scope of view. Even if you can overcome this, if the CSM is pointed nose down as you suggest how is it possible to film the entire sequence using a right angle mirror. I have attached an Apollo photo of the Command Module and how the DAC camera was deployed with a right angle mirror. As you can see (when you re-orient the photo so the Astronaut's head is at the top of photo) if the CSM is nose down (astronauts head is at the top of the CM cone) the right angle mirror would be shooting off into space away from the moon's surface. Futhermore, if you look at the photo, the question arises why would you want to use a mirror anyways? If you just remove the right angle mirror from the DAC, the camera is pointed in the direction you suggest in your hypothesis . Of course, as you can see the window is too small and on angle to get a clear view in that direction. So any shot of LM in a CM nose down position will undoubtedly have part of its view obscured by the window frame. The question then is if your supposition is correct why is A12 rendezvous clip not obscured by the window frame at all. Again, as you can see by the DAC setup in the CSM, given these clips were shot into a mirror, demonstrate they were not likely shot the way you are suggesting. In fact, if the rendezvous took place the way you are suggesting there is no reason a mirror should have been used at all. Let me know if there is way this could done.

Also no one has taken a shot on why the A11 footage of the LM's movements and rotations appear to be mechanical in nature and not natural. To the point, some of the rotations appear to show the LM 'bouncing back' in the opposite direction after a rotation ends. Does anyone have any ideas? 

I would also like to further add, not only were these films shot using a mirror, the DAC, unless I am mistaken (let me know), did NOT have a viewfinder (apparently it had a attachable ring sight that could be used when hand held). Lets think about that. We have these perfectly framed rendezvous clips. Never out of focus nor out of frame with the LM moving on the same Y axis the entire time. All shot in a 1.5 inch right angle mirror from a camera is which you can't even view what you are filming. This would be hard enough to remain focus in on an object miles out with a view finder. (Try it with your own camera, not easy) Now add a small mirror angled in a different direction, on top of no view finder and remember keep the camera stationary the entire time. These are truly amazing films.

[Jason Thompson]

JFB and Jason Thompson, your suppositions actually help my case. Jason, even if one agrees to your plotting of the LM relative to the CSM and the range of view from the CM window

The concept of an ilustrative example totally escapes you, doesn't it? I never said the spacefraft were oriented in that way. It is simply an illustration of how the LM can remain in the same relative position within the field of view, and how the background will change over time.

I ask again, do you understand that neither spacecraft is in powered flight at the time? Do you still believe they need to 'pick out' the LM in the distance to aim the camera? Do you understand that the CSM remains pointing the same way as per the illustration during the orbit?

It was was filmed into a mirror. More specifically a right angle mirror.

So?

First off the use of a 1.5 inch mirror will greatly curtail the scope of view.

Why? Explain exactly how the use of a 1.5 inch miirror would restrict the view if it was placed close enough to the camera lens.

Even if you can overcome this, if the CSM is pointed nose down as you suggest

I never said it was. But by definition during one orbit about half of it has the LM pointed 'nose down' to some degree, while the other half is 'nose up' The CSM remains in one fixed orientation in space, not relative to the lunar surface. Do you understand this?

the question arises why would you want to use a mirror anyways? If you just remove the right angle mirror from the DAC, the camera is pointed in the direction you suggest in your hypothesis

Really? And you can't see any way that using a mirror helps you out in terms of where the body of the camera goes?

Of course, as you can see the window is too small and on angle to get a clear view in that direction.

You have a strange fixation about the size of windows. You made the same argument in the LM thread. Why don't you understand that the field of view from a window depends on where you are in relation to it? If I stand back from a 9-inch window my field of view of what is outside it is heavily restricted. If I put my face (or a camera) up close it's not. You can try this yourself with a piece of card with a hole in it.

Also no one has taken a shot on why the A11 footage of the LM's movements and rotations appear to be mechanical in nature and not natural.

No-one has taken a shot on why footage of the movement of a mechanical object looks mechanical? Are you serious?

To the point, some of the rotations appear to show the LM 'bouncing back' in the opposite direction after a rotation ends. Does anyone have any ideas?

See if you can figure out how the LM stops a rotational manoeuvre and that might answer your question.
 

did NOT have a viewfinder (apparently it had a attachable ring sight that could be used when hand held). Lets think about that. We have these perfectly framed rendezvous clips. Never out of focus nor out of frame with the LM moving on the same Y axis the entire time.

Again, you make the mistake of assuming you need to be able to see what you're filming to find it. Again I ask, do you understand that neither vehicle was under powered flight during the footage? THat is actually a key part of understanding how they could set up a camera to capture something without using a viewfinder. THe physics of the situation dictates where everything is in relation to everything else.

[Zakalwe]

. Never out of focus nor out of frame

What was the f-stop and aperture of the camera? What was the focal length of the lens? Do you understand the relationship between aperture and DoF?


By the way, PLEASE ANSWER YOUR OUTSTANDING QUESTIONS.

[Northern Lurker]

First off the use of a 1.5 inch mirror will greatly curtail the scope of view.

Why? Explain exactly how the use of a 1.5 inch miirror would restrict the view if it was placed close enough to the camera lens.

Of course, as you can see the window is too small and on angle to get a clear view in that direction.

You have a strange fixation about the size of windows. You made the same argument in the LM thread. Why don't you understand that the field of view from a window depends on where you are in relation to it? If I stand back from a 9-inch window my field of view of what is outside it is heavily restricted. If I put my face (or a camera) up close it's not. You can try this yourself with a piece of card with a hole in it.

Tangible, medieval example of this are arrowslits. Narrow slit is difficult target for attacking archer in distance but defending archer just next to arrowslit has much better fields of view and fire.

Lurky

[Von_Smith]

HI JFB and Jason Thompson, Bknight, Molesworth, OBM et al

I appreciate your responses to my claims (and Jay, I do believe I am attempting to reciprocate, albeit I don't have enough time in the day to respond to everyone.

First, BKnight, the distance is more than 3600 feet between the LM and CSM. The communication you quote is the first dialogue when they come around from the far side of the moon. The A11 clip is 20 minutes in real time. It took 55 minutes for the LM to transition from its lunar orbit to the CSM's lunar orbit approximately 12-14 miles higher. Clearly that points to a greater separation between the LM and CSM at the start of the clip than you are suggesting.

WARNING:  Liberal arts major attempting science here.
 
One relevant thing the quote documents is that the two craft were closing at about 10m/s while they were coasting to rendezvous. 

The ascent stage was roughly a cube 4 meters on a side.

The visual acuity of the human eye is about one minute of arc.

A 4 meter cube will subtend a minute of arc at about 13.75 km.

At 10m/s the LM will close 12 km distance with the CSM in 20 minutes.

So it doesn't seem that implausible to me that you'd be able to see the approaching LM from the CSM for "18-20 minutes".

And I personally can only see the LM in the frame for about 3:40 or so of the clip in question, so it's more like 15 minutes real time, not 18-20.  We're probably watching a closing distance of <10km or so over the course of the clip?  I think?

I'm sure more knowledgeable people can tweak my back of the envelope guesstimates here.

[bknight]

HI JFB and Jason Thompson, Bknight, Molesworth, OBM et al

I appreciate your responses to my claims (and Jay, I do believe I am attempting to reciprocate, albeit I don't have enough time in the day to respond to everyone.

First, BKnight, the distance is more than 3600 feet between the LM and CSM. The communication you quote is the first dialogue when they come around from the far side of the moon. The A11 clip is 20 minutes in real time. It took 55 minutes for the LM to transition from its lunar orbit to the CSM's lunar orbit approximately 12-14 miles higher. Clearly that points to a greater separation between the LM and CSM at the start of the clip than you are suggesting.

WARNING:  Liberal arts major attempting science here.
 
One relevant thing the quote documents is that the two craft were closing at about 10m/s while they were coasting to rendezvous. 

The ascent stage was roughly a cube 4 meters on a side.

The visual acuity of the human eye is about one minute of arc.

A 4 meter cube will subtend a minute of arc at about 13.75 km.

At 10m/s the LM will close 12 km distance with the CSM in 20 minutes.

So it doesn't seem that implausible to me that you'd be able to see the approaching LM from the CSM for "18-20 minutes".

And I personally can only see the LM in the frame for about 3:40 or so of the clip in question, so it's more like 15 minutes real time, not 18-20.  We're probably watching a closing distance of <10km or so over the course of the clip?  I think?

I'm sure more knowledgeable people can tweak my back of the envelope guesstimates here.

See post number 41 and from AFJ Collins began filming the approach at .7 mile a little over 3600 feet, not even KM, now if you are referring to A12.

145:15:07 Gordon: What do you have on the tube?
145:15:10 Carr: Nothing yet, Dick.
145:15:17 Gordon: Okay. I'm going to roll a little more and give you some more High Gain.
145:15:34 Carr: Clipper, Houston...
145:15:37 Conrad: 38 feet per second.
145:15:40 Carr: Clipper, Houston. We're going to need about a 60-degree roll right to get to High Gain.
145:15:48 Gordon: You're getting it. [Long pause.]
Public Affairs Office - "Pete Conrad reporting a closure rate of 38 feet per second, about 1.7 nautical miles away. 145 hours, 16 minutes; standing by for any television transmission."

As far as I could see no reported time for the film, if it was done concurrently with the TV, But th distance was 1.7 miles, again not the 60000 that jrk reported.  Very easy distant to find and film/TV an approaching craft that was approximately 4 m on a side.

[Von_Smith]

HI JFB and Jason Thompson, Bknight, Molesworth, OBM et al

I appreciate your responses to my claims (and Jay, I do believe I am attempting to reciprocate, albeit I don't have enough time in the day to respond to everyone.

First, BKnight, the distance is more than 3600 feet between the LM and CSM. The communication you quote is the first dialogue when they come around from the far side of the moon. The A11 clip is 20 minutes in real time. It took 55 minutes for the LM to transition from its lunar orbit to the CSM's lunar orbit approximately 12-14 miles higher. Clearly that points to a greater separation between the LM and CSM at the start of the clip than you are suggesting.

WARNING:  Liberal arts major attempting science here.
 
One relevant thing the quote documents is that the two craft were closing at about 10m/s while they were coasting to rendezvous. 

The ascent stage was roughly a cube 4 meters on a side.

The visual acuity of the human eye is about one minute of arc.

A 4 meter cube will subtend a minute of arc at about 13.75 km.

At 10m/s the LM will close 12 km distance with the CSM in 20 minutes.

So it doesn't seem that implausible to me that you'd be able to see the approaching LM from the CSM for "18-20 minutes".

And I personally can only see the LM in the frame for about 3:40 or so of the clip in question, so it's more like 15 minutes real time, not 18-20.  We're probably watching a closing distance of <10km or so over the course of the clip?  I think?

I'm sure more knowledgeable people can tweak my back of the envelope guesstimates here.

See post number 41 and from AFJ Collins began filming the approach at .7 mile a little over 3600 feet, not even KM, now if you are referring to A12.

145:15:07 Gordon: What do you have on the tube?
145:15:10 Carr: Nothing yet, Dick.
145:15:17 Gordon: Okay. I'm going to roll a little more and give you some more High Gain.
145:15:34 Carr: Clipper, Houston...
145:15:37 Conrad: 38 feet per second.
145:15:40 Carr: Clipper, Houston. We're going to need about a 60-degree roll right to get to High Gain.
145:15:48 Gordon: You're getting it. [Long pause.]
Public Affairs Office - "Pete Conrad reporting a closure rate of 38 feet per second, about 1.7 nautical miles away. 145 hours, 16 minutes; standing by for any television transmission."

As far as I could see no reported time for the film, if it was done concurrently with the TV, But th distance was 1.7 miles, again not the 60000 that jrk reported.  Very easy distant to find and film/TV an approaching craft that was approximately 4 m on a side.

Right, I saw that, but since jrknowing was disputing that, I took a different approach:  even using his own math, there's no reason to assume the LM travels any where near 60000 feet in over the interval filmed.

[gillianren]

Tangible, medieval example of this are arrowslits. Narrow slit is difficult target for attacking archer in distance but defending archer just next to arrowslit has much better fields of view and fire.

Quite right.  As if that property of a window has been known for centuries!  The design was even such that it was as small as it could be and still be useful, because practical engineering was already a thing.

[Von_Smith]

HI JFB and Jason Thompson, Bknight, Molesworth, OBM et al

I appreciate your responses to my claims (and Jay, I do believe I am attempting to reciprocate, albeit I don't have enough time in the day to respond to everyone.

First, BKnight, the distance is more than 3600 feet between the LM and CSM. The communication you quote is the first dialogue when they come around from the far side of the moon. The A11 clip is 20 minutes in real time. It took 55 minutes for the LM to transition from its lunar orbit to the CSM's lunar orbit approximately 12-14 miles higher. Clearly that points to a greater separation between the LM and CSM at the start of the clip than you are suggesting.

WARNING:  Liberal arts major attempting science here.
 
One relevant thing the quote documents is that the two craft were closing at about 10m/s while they were coasting to rendezvous. 

The ascent stage was roughly a cube 4 meters on a side.

The visual acuity of the human eye is about one minute of arc.

A 4 meter cube will subtend a minute of arc at about 13.75 km.

At 10m/s the LM will close 12 km distance with the CSM in 20 minutes.

So it doesn't seem that implausible to me that you'd be able to see the approaching LM from the CSM for "18-20 minutes".

And I personally can only see the LM in the frame for about 3:40 or so of the clip in question, so it's more like 15 minutes real time, not 18-20.  We're probably watching a closing distance of <10km or so over the course of the clip?  I think?

I'm sure more knowledgeable people can tweak my back of the envelope guesstimates here.

See post number 41 and from AFJ Collins began filming the approach at .7 mile a little over 3600 feet, not even KM, now if you are referring to A12.

145:15:07 Gordon: What do you have on the tube?
145:15:10 Carr: Nothing yet, Dick.
145:15:17 Gordon: Okay. I'm going to roll a little more and give you some more High Gain.
145:15:34 Carr: Clipper, Houston...
145:15:37 Conrad: 38 feet per second.
145:15:40 Carr: Clipper, Houston. We're going to need about a 60-degree roll right to get to High Gain.
145:15:48 Gordon: You're getting it. [Long pause.]
Public Affairs Office - "Pete Conrad reporting a closure rate of 38 feet per second, about 1.7 nautical miles away. 145 hours, 16 minutes; standing by for any television transmission."

As far as I could see no reported time for the film, if it was done concurrently with the TV, But th distance was 1.7 miles, again not the 60000 that jrk reported.  Very easy distant to find and film/TV an approaching craft that was approximately 4 m on a side.

Right, I saw that, but since jrknowing was disputing that, I took a different approach:  even using his own math, there's no reason to assume the LM travels any where near 60000 feet in over the interval filmed.

Another question:  are we sure the DAC was filming at 6 fps, as opposed to 12?

[Von_Smith]

Another question:  are we sure the DAC was filming at 6 fps, as opposed to 12?

I was able to sneak home for lunch and can have a peek at the Apollo 11 Flight Journal now.  So, to reconcile distances: 


At 127:43:43, they're going 9.5 m/s.
I had forgotten they were breaking during this time rather than just coasting (I was thinking a bit too Kerbal for my own good).  By 127:46:13 they're already down to 3.4 m/s.  And by 127:52:05 they were already stationkeeping.  So even ignoring Collins' comments, the distances covered would be even less.

So 2:30 at an average speed of ~5.6 m/s ~840m.  And another 400 seconds at an average speed of 1.7m/s would cover 680m.  1.52 km, plus whatever their separation was at that point.  Compared to 1.7 km Collins called out.  So it checks out! 

[Von_Smith]

Another question:  are we sure the DAC was filming at 6 fps, as opposed to 12?

I was able to sneak home for lunch and can have a peek at the Apollo 11 Flight Journal now.  So, to reconcile distances: 


At 127:43:43, they're going 9.5 m/s.
I had forgotten they were breaking during this time rather than just coasting (I was thinking a bit too Kerbal for my own good).  By 127:46:13 they're already down to 3.4 m/s.  And by 127:52:05 they were already stationkeeping.  So even ignoring Collins' comments, the distances covered would be even less.

So 2:30 at an average speed of ~5.6 m/s ~840m.  And another 400 seconds at an average speed of 1.7m/s would cover 680m.  1.52 km, plus whatever their separation was at that point.  Compared to 1.7 km Collins called out.  So it checks out!

ETA:  Collins gave the distance as 1.3 km, not 1.7.  Still a close enough agreement.