Blue Marble photo discussion

Blue Marble photo discussion
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[edit] Flight Dynamics

At the time of the S-IVB separation maneuver, the spacecraft was oriented at 274, 164, 00.

  • Flight Plan:[1] E. Guidance and Navigation, 1. REFSMMAT Definitions: (a) The "Launch Pad" REFSMMAT is used for launch, TLI, and TD&E. This REFSMMAT places the IMU X-axis along the launch azimuth at the pad and the Z-axis along the negative radius vector.
  • Apollo 8 A8FJ attitude display of 162° in roll, 90° in pitch and 0° in yaw is achieved. The value for roll is derived from the current value for roll (90°) plus the flight azimuth of 72°
  • Apollo 15 A15FJ The angle between north and the groundtrack of the vehicle's flight path is called the flight azimuth. For this launch, it is to be 80.088° or slightly north of east.
  • Apollo 17 Apollo by the Numbers Between 000:00:12.9 and 000:00:14.3, the vehicle rolled from a launch pad azimuth of 90° to a flight azimuth of 91.503°.
  • For the Apollo 17 launch, the attitude display would have been:
    • 181.5° in roll
    • 90° in pitch
    • 0° in yaw
    • Does this means that if the spacecraft was in earth orbit directly above the pad, facing forward with the windows down, the attitude would read 0, 0, 0?
  • Flight transcript: 004:34:57 Obermeyer: "17, Houston... We've got some new - new angles here for you... They're your NOUN 22 attitude maneuver for APS burn out of the hatch window. They're in the middle of the page L/3-5... Instead of 270, we want 274... the next one, the 129.8, change that to 164. And 4.3 on the yaw, change that to zero. It's close enough; zero on the yaw..." Schmitt: "Okay. We got them 274, 164, 00."
  • High gain antenna: "and the high-gain angles that you've got on the Flight Plan are close enough and should do it."


  • Verb 49: Request Crew Defined Maneuvre Routine: 274°, 164°, 0°
  • High gain antenna: pitch -1°, yaw 273°

The APS burn attitude was 274, 164, 00. Relative to the launch attitude, this means

  • +92.5° in roll
  • +74.0° in pitch
  • 0° in yaw

The high gain antenna points towards the Earth (at the current tracking station - ) and the angles are relative to the CM axes. Pitch -1°, yaw 273° means we're essentially pointing straight at the Earth (0°, 270°).

  • +° in roll
  • +° in pitch
  • ° in yaw

So, what attitude does NOUN 22 274, 164, 00 put the spacecraft in relative to the Earth? Roll, pitch, yaw?

  • Attitude maneuver for APS burn out of the hatch window - middle of page L/3-5 - NOUN 22 angles: 274, 164, 00. [Transcript]
  • Cernan: "Noun 22 showed you the new alignment angles" [Tech debrief?]

The following is based on Wikipedia:Flight dynamics: In flight dynamics, pitch, roll and yaw angles measure changes in attitude, relative to the equilibrium orientation of the vehicle. Spacecraft generally have no discernible front, side, or bottom, so the axes are oriented relative to the pilot's physical orientation at the flight control station.

  • The positive X axis, points towards the nose.
  • The positive Y axis goes out the right side of the vehicle
  • The positive Z axis goes out the underside of the vehicle

Roll, pitch and yaw constitute rotation or attitude around X, Y, and Z, respectively. A local Earth axis set is used, with the X and Y axis in the local horizontal plane, usually with the x-axis coinciding with the projection of the velocity vector at the start of the motion. The z axis is vertical, pointing generally towards the Earth's centre, completing an orthogonal set.

Flight Plan: E. Guidance and Navigation, 1. REFSMMAT Definitions,

(a) The "Launch Pad" REFSMMAT is used for launch, TLI, and TD&E. This REFSMMAT places the IMU X-axis along the launch azimuth at the pad and the Z-axis along the negative radius vector.

(b) The "PTC" REFSMMAT is used for all midcourse maneuvers (except MCC-7) and for other operations during TLC and TEC. This REFSMMAT places the X-axis in the ecliptic plane and perpendicular to the earth-moon line projection in the ecliptic plane at the average time of transearth injection for the monthly launch window and azimuth range. The Z-axis is perpendicular to the ecliptic and directed south. At the beginning of the PTC Mode the spacecraft maneuvers to an FDAI display of pitch 90o or 270o.

[edit] Flight Transcript

004:47:05 Evans: Okay. POWER's OFF. Hey, Jack. Hand me the Hasselblad. I think we're bowing the right direction. Yes, the Moon is there. The Earth is - that's the Earth. (photo AS17-148-22699-702) Evans: The Earth just fills up window 5. Okay, f infinity, about a 250th. (AS17-148-22703,4,5,6,7)

004:59:05 Cernan: Bob, I know - I know we're not the first to discover this- but we'd like to confirm, from the crew of America, that the world is round. Obermeyer: Roger. That's a good data point. Have you gotten a good look at any of that weather down there on the Antarctic?

Cernan: Well, Ron's at window number 1 - maybe he can tell you a little about it. Evans: You know, it's real funny there in Antarctica the - You can see the snow, but there isn't any weather at all in it. All of the weather's around it in the water. Schmitt(?): That's where the moisture is. I don't know what to take a picture of. Evans: I can't see the U.S. at all.

Evans: It's in the Volkswagen pouch down there. Schmitt: No, I'll change the lens now. (AS17-148-22723-5) Obermeyer: 17, Houston. It's about 30 seconds from the evasive maneuver burn. Cernan: Okay. Evans/Cernan?: Here, Jack, can you see him good? Evans/Cernan?: Check the settings there. I took an f/22 stop. (AS17-148-22726,7,8)

005:03:19 Cernan: here it goes, Bob. Schmitt: There it goes; finally. Obermeyer: Roger.

Evans: Houston, magazine November November is on about 123 right now.

005:29:53+ Schmitt: Bob, I'm looking over Gene's shoulder here at the Earth, and it must be an awful clear day for the so-called convergence zone across Africa. Gene, I think, indicated, as it looked to us as we crossed it earlier, most of Africa is clear. Only some - probably are broken and scattered clouds - cumulus in the east central portion that are running along the line of - north/south lines.

005:49:03+ Obermeyer: Roger. Did you get any pictures of that, Jack? Schmitt: Oh, yes. We got some pictures earlier. I'm going to get another one here in a minute. I'll tell you, if there ever was a fragile-appearing piece of blue in space, it's the Earth right now. (AS17-148-22732,3)

[edit] Quotations

"The crew accept credit for that picture as a whole. I've actually been to events where all three of them kind of jokingly take credit for it. And we've never really been able to quite pin down which one of the crewmen, Cernan, Evans or Schmitt took the picture. The picture itself was not as much of a stratagem as one might think. It was more or less look at that beautiful thing there, let's take a picture of it. ... No one at that time in our photo lab had any idea I think of how long lasting it would..." -- Mike Gentry, NASA Media Resource Centre, 1999[2]

"Early in the mission, Astronaut Ron Evans made his most notable photographic contribution; he took a picture that will rank among the classics of the space program. As Apollo sped toward the moon after blasting into its translunar trajectory, he pointed his camera back toward home and caught a stunning view of the earth, with the side visible to the astronauts completely illuminated..." -- Time Magazine, January 8, 1973[3]

"... highlighted eight Apollo 17 photos released by the Space Agency Saturday. Harrison H. "Jack" Schmitt captured the view of Africa, Arabia and the Antarctica polar ice cap a few hours after he and Eugene A. Cernan and Ronald E. Evans blasted away from Earth Dec. 7." -- UPI wire story, Saturday December 24, 1972[4]

[edit] References

  1. Apollo 17 Flight Plan
  2. Alexandra de Blas interviewing Mike Gentry, NASA Media Resource Centre, Johnson Space Centre , Houston, Texas, World Environment Day: Spaceship Earth, Earthbeat (Australian Broadcasting Corporation - Radio National), Saturday, June 5, 1999
  3. "Portfolio from Apollo", Time Magazine, January 8, 1973.
  4. UPI, "Astronauts Relax; Photos Of Moon Voyage Released", The Times Standard, Saturday December 24, 1972, Eureka, California, Page: 9 (Subscription required)