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Apollo 17: The Blue Marble - Geometry

By Eric Hartwell - Last updated February 11, 2006

This section:

Getting an Angle (new)

Transposition and docking was filmed using the 16 mm Data Acquisition Camera looking through the CMP rendezvous window 2. The 18 mm lens used has a viewing angle of 24 x 32 degrees.

I've determined the actual orientation of the S-IVB/LM relative to the Earth by pasting together the movie frames from the pitch maneuver.

The resulting image, below, is a virtual 110° wide-angle view (the standard Hasseblad lens has a 38° field of view).

Since the pitch maneuver was performed at a constant rate, it's possible to measure the angles directly from the combined image. The center of the Earth is 70° down from the CSM / S-IVB/LM axis (this image is rotated sideways for convenience in viewing).

 

Who Gets the Window Seat?

The Apollo Command Module had five windows. The image at left of Apollo 17's Command Module, America from frame AS17-145-22272 shows the location of all five windows. Windows 1 and 5 are approximately square panes and are flush with the CM surface. Windows 2 and 4 are the rendezvous windows and are recessed to allow them to face forward. Window 3 is circular (despite the squareish external appearance) and is built into the main hatch (NASA).

The normal seating plan has the Commander (Cernan) in the left seat, the Command Module Pilot (Evans) in the middle seat, and the Lunar Module pilot (Schmitt) in the right seat [yes, I fixed the Wikipedia entry]. However, right after the end of the earth departure burn, Evans moved to the left seat to control the Command/Service Module during transposition and docking with the Lunar Module. From inside the capsule, Evans was on the left and Schmitt on the right.

The internal size and shape of each window can be easily seen in this collection of Command Module window covers from Historic Space Systems. Made of aluminum and carefully machined to reduce weight, the window covers were used to darken the cabin interior. The outside is painted white, and a rubber seal prevents light leakage. (Credit: Historic Space Systems)


Left hand side window cover

Left hand rendezvous window cover

 


Aft, or hatch, window cover

This NASA diagram shows the geometry of the view through the rendezvous windows 2 and 4.

 


One of the most worrisome items astronauts found
in the CM arrangement was an "elbow-shoulder
clearance problem," Four years later, in 1968, this
problem still vexed astronauts Walter Schirra,
Donn Eisele, and Walter Cunningham, the first crew
to fly an Apollo spacecraft.
-- Chariots For Apollo, ch5-3
 

Inside the Cabin

The cone-shaped Apollo CM spacecraft was divided into three compartments: forward, crew, and aft.

The forward compartment was at the cone's apex, the crew compartment was in the center, and the aft compartment was in the base, or blunt end, of the craft. The forward compartment contained the parachutes and recovery equipment.

The crew compartment had a volume of 210 cubic feet. It contained three couches for the crew during launch and landing.

The couches were arranged so that each astronaut faced the main instrument panel. During flight, the astronauts could fold-up the couches to make more room in the spacecraft.

Near the feet of the couches, in the lower equipment bay, there was enough room to stand up.

Needless to say, space inside the cabin was extremely limited, especially when the astronauts were wearing their bulky spacesuits.


Apollo command module - general layout (Credit: NASA)


Couch suspension system inside the command module


Internal construction of the Apollo command module

 


Apollo-15 Command Module , Equipment Stowage (credit: NASA)

[U4] 4 cassettes, 4 batteries for tape recorders / 10 x 40 monocular / intervalometer (Hasselblad) / 250mm lens
[A1] 70 mm camera adapter / H2 gas separator in bag 5 tissue dispensers / 2 penlights in bag / tool set / pressure garment O2 interconnect, 3 in bag / snag line in bag / 2 probe stowage straps / 3 temporary stowage bags
[A3] 4 CO2 absorbers / fire extinguisher / acoustic tone booster in bag / remote control cable
[A5] 2-speed interval timer / 5 sleep restraint ropes / 16mm camera sextant adapter / 3 headrest pads
[A6] TV monitor, monitor cable, and mounting bracket / 2 CO2 absorbers
[A8] 3 pilot preference kits / inflight exerciser / 2 tissue dispensers / 3 constant wear garments / extravehicular mobility / unit maintenance kits / 3 light-weight headsets / relief receptacle assembly and strap / 16mm camera with / magazine, powerpack, and 2 film magazines in bag / 10mm lens / decontamination bags / O2 umbilical / interconnect / contingency lunar sample return container
[R3] data card kit / eyepatch / 2 meter covers / floodlight glare shield / fuse (16mm camera) / 6 flight data file clips / flight data file books / lunar module transfer data card kit and flight data file books
[R4] 2 rucksack survival kits
[R10] 2 sanitation stowage boxes / 30 fecal collection assemblies / water panel coupling assembly / waste management system water panel, quick disconnect, power cable, and quick disconnect pressure cap
[R11] 3 urine transfer systems / spare urine receiver assembly / roll-on cuff (red, white, blue)

VW Bags

The temporary stowage bags are used for temporary stowage of small items and permanent stowage of dry refuse or "trash". The waste bag, nicknamed the "VW" bag, is a two-pocket unit. The outer pocket is deep, about 3 feet by 1 foot by 3 inches and is held shut by a bar spring. The inner pocket is flat, about 1 by 1 foot and is held shut by a rubber bungee. The bags are attached to the girth shelf and LEB by snaps. The outer bag is for dry uncontaminated waste matter and the inner bag serves as temporary stowage for small items. There are three waste bags, one for each crewman. The Commander's bag attaches to the left girth shelf, the LM pilot's to the right girth shelf, and the CM pilot's, the LEB. They are stowed in a storage locker at launch and entry.

Incidentally, Apollo 17 tested two new food types - irradiated ham and a nutritional fruitcake.

Here are some excellent photos of Apollo 9's Command Module, courtesy of Stewart Bailey of the Michigan Space and Science Center. Enjoy the full set at apollosaturn.com:


Left and above: The photo at far right shows the left-hand seat, from where the CMP controls the CSM during transposition and docking with the Lunar Module.

Right: The view looking forward (up from the seat back) through the docking rendezvous window.

The Command Module Pilot controls the Command and Service Module during transposition and initial docking with the Lunar Module. On return from the moon, the Lunar Module manoeuvres to complete the docking operation. In either case, a lighted reticule on the window helps the CM pilot check the lineup of the two vehicles by placing cross lines on the target just to the left of the lunar module’s docking cone.

Left: Artist's concept of Apollo 12 Command Module's interior (NASA imag: S69-58005)

Right: one of a series of drawings by Russell Arasmith used by NASA to illustrate the Apollo 9 mission.

As the LM manoeuvres through the final sequence to complete the docking operation, a lighted reticule on the window helps the CM pilot to check the lineup of the two vehicles by placing cross lines on the target just to the left of the lunar module’s docking cone.

Finally, here are more pictures of the hatch window (3), the right-hand side LM pilot's windows (4 and 5)., and an exterior view of  Apollo 17's window (4).


Apollo 11 hatch photo courtesy Kipp Teague's Project Apollo Archive


Right-hand/LM pilot's seat, (Stewart Bailey,
Michigan Space and Science Center)


Apollo 17 capsule rendezvous
window 4 (AS17-148-22755)

The TD&E Railway

After inflight systems checks during two Earth orbits lasting 3 hours, the S-IVB was fired a second time at 3:12 GET for 6 minutes, sending the spacecraft towards the moonat 35,555 ft/sec. At 3:42, the CSM was separated from the S-IVB stage, transposed, and docked at 3:57. The docked spacecraft were ejected from the S-IVB at 4:45. The S-IVB stage was fired for 80 seconds at 5:03 to start it on its separate trajectory to impact the Moon.

Unlike most of the major maneuvers performed during the course of the mission, Transposition, Docking and Extraction (TD&E) is flown almost entirely by hand. This is where the Command Module Pilot (CMP) gets to do some of that “Pilot Stuff”.


Illustration based on TD&E diagram in Chariots For Apollo, ch5-3

As the name implies, the process consists of three phases:

  1. Transposition: The maneuver begins with separation of the CSM from the S-IVB (containing the LM), with the SLA panels tumbling away into space. Right after separation, a pitch up maneuver is initiated, rotating the CSM 180˚ to face the LM/S-IVB.

  2. Docking: Next, the CSM is translated with plus-X thrusters, closing the distance between the CSM and the LM/S-IVB at rate of approximately 1 ft/sec. The CSM is then rolled approximately 45˚ left to align the COAS (Crew Optical Alignment Sight - mounted to the #2 Left Rendezvous Window frame) with the docking target on the LM. Y and Z thrusters are also used to fine tune the approach. The final few feet are covered at a closure rate of approximately 0.1 ft/sec.

  3. Extraction: After docking the cabin pressures of the two spacecraft are equalized and the CSM forward hatch removed to inspect the docking latches. Electrical umbilical cables are connected within the tunnel and the hatch reinstalled. After further systems checks the CSM/LM stack is then ejected from the S-IVB, followed by a 1 ft/sec separation maneuver.

Once the two spacecraft are well clear, ground control points the S-IVB away from the direction of travel and fires its engine to send it on a separate trajectory to crash into the moon.

Looking Out/Down/Back

What the astronauts would see looking out the windows over the LM back towards the S-IVB and the Earth.

It's important to remember that the CSM was rolled approximately 45˚ left from the front of the LM. Many sources (including NASA) erroneously show the two spacecraft with their hatches in line. This orientation is most evident in the famous photo of the Apollo 9 CSM "Gumdrop" from the LM "Spider", AS9-20-3064.

Click for larger image

In the closeup above, the image has been rotated so that David Scott is standing upright relative to the Command Module's open hatch. Note the relative orientation of the CM's hatch window and the LM's VHF antenna and RCS thrusters. These are reference marks that can be used to determine which window was used to take photos during Apollo 17's TD&E.


View of LM during docking approach - simulated with Orbiter, left, and real (AS17-148-22697), right

Which Window Was It?

Although NASA doesn't attribute photos to any particular astronaut, it's possible to tell who took many of the pictures based on the mission timeline and the window that was used. During TD&E, Cernan was taking photos from the center position (windows 2,3,4) and Schmitt from the right-hand position (windows 4,5).

Using photos rotated so the top is "up" relative to the Command Module's -Z axis, it's possible to guess which window was used by comparing the relative angles of the LM's VHF antenna and RCS thrusters. From window 2 the antenna would have been almost in line with the RCS, while from window 3 it was well to the left. The VHF antenna would not have been visible from window 4, or the side windows 1 and 5.

Note: The Apollo 15 Flight Journal - Transposition, Docking and Extraction

From the 1971 Technical Debrief:
Scott  - "That's a pretty good thump when it goes off - those springs pushing out - but there was no question that we had had extraction. You could see the S-IVB going away, [speaking to Al] couldn't you? Or could you?"
Worden - "No, I couldn't. Jim could. I couldn't see out my window. I watched the EMS [Entry Monitor System]."
[Since Al's window is right up against the docking target on the LM, his forward visibility is limited. The digital display below the EMS scroll can be set to display changes in velocity, or Delta-V.]
[As Apollo 15 drifts away from the S-IVB, it is maneuvered to an attitude where the empty stage can be viewed through window 3, the hatch window. The crew can provide an assurance that the two great vehicles are sufficiently clear of each other to permit the S-IVB to maneuver to a trajectory which will seal its final fate - a high speed impact with the Moon.]

[Scott, from the 1971 Technical Debrief - "The evasive burn was a very slow, low thrust maneuver. We could see some of the propellant coming out. There was a very fine mist if you looked very carefully, and the S-IVB moved very slowly along its plus X-axis. I rather expected a burn there - some sort of impulsive Delta-V - but it, was a very slow thing. It wouldn't be any problem getting out of its way, if you were in its way."]

 


Cernan probably took the first few frames from the left rendezvous window (2), then switched to the hatch window (3) for the remainder.

The astronauts were still in their suits during TD&E, so they couldn't easily change places. Evans was busy flying the CSM/LM spacecraft. Therefore,

  • Photos from windows 2 and 3 were almost certainly taken by Cernan.
  • Photos from window 4 could have been taken by Cernan or Schmitt.
  • Photos from window 5 were almost certainly taken by Schmitt.
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