I hope this question is not too broad. It is inspired by another question.

We know that ISS keeps its nadir pointing to Earth's surface.

What about other manned spacecraft?

Do/did they have distinct modes of attitude to Earth? What were motivations of spacecraft attitudes? I couldn't find info for most of historic manned spacecraft, at least now...

Skylab was keeping orientation to maximize insolation of fixed solar panels.

  • Did Mir, Salyut space stations do the same as Skylab? (I suppose yes but have no proof)

  • Did Mercury, Gemini craft have attitude requirements relative to Earth?

  • Did Apollo have attitude requirements relative to Earth in different phases of missions? (I know at least in lunar transfer it was spin-stabilised)

    According to ESA site Soyuz spacecraft are spin-stabilised during long 2-day flights, with rotation axis perpendicular to sunlight to maximize insolation of solar panels. During short 6-hour flights Soyuzes are not spin-stabilised. But there is no info what is attitude mode in the short-flight case.

  • Did Space Shuttle have attitude requirements relative to Earth?

  • $\begingroup$ Antennas should be pointed to Earth, solar panels to Sun, cameras or sensors to their destination. Radiators for cooling away from Sun and Earth. Humans on board would like a window with Earth view. $\endgroup$ – Uwe Jun 29 '18 at 9:15
  • $\begingroup$ @Uve I'm sorry, the title was not clear enough. I have changed it because I'm interested espesially about manned spacecraft. $\endgroup$ – Heopps Jun 29 '18 at 10:52
  • $\begingroup$ My comment is valid for manned spacecrafts too. $\endgroup$ – Uwe Jun 29 '18 at 10:58

I believe the shuttle normally orbited upside-down, i.e. with its upward axis pointing towards Earth's surface, though it would maneuver into other attitudes as needed during a mission. It was oriented retrograde (tail-first) to minimize the danger from orbital debris impacts.

In the first Mercury sub-orbital flights, there was very little time between orbital insertion and preparation for re-entry, so the capsule immediately rotated into a tail-first attitude to present the heat shield for re-entry.

In the orbital Mercury flights, the default was to stay in that retrograde attitude, but a major purpose of the missions was to test manual and automatic attitude control. Often the capsule would be held with a substantial downward pitch so the astronaut could observe Earth's surface.

Likewise, the Gemini flights were often testing orbital maneuvering, so they would maneuver as needed, but again I think the default attitude was tail-first, head-up. During Ed White's spacewalk, the capsule appears to be in retrograde attitude, perhaps a little nose-down.

Apollo, on lunar missions, I believe stayed in prograde attitude from orbital insertion until it was coasting translunar -- it was attached to a rather large rocket stage, so wouldn't maneuver casually. After extracting the lunar module, it would orient itself north-south and roll on its long axis for thermal control. On the earth orbit missions it would be oriented according to the needs of whatever test it was carrying out; I don't know what its default was, but probably either prograde or retrograde, head-up.

Mir was the first Russian station to have reaction wheels for attitude control; I assume it maintained a constant orientation relative to Earth's surface like ISS does. The Salyuts may have drifted much of the time in order to conserve attitude control propellant.

  • 3
    $\begingroup$ This is true information concerning the Shuttle Orbiter. Also should note that, while said Orbiter was in the stated attitude, everything else being equal, we preferred that its aft end be pointed in the direction of its orbital velocity vector, as said attitude minimized the danger that could arise due to orbital debris impacts. Also, in general, attitude (as discussed in the current context) should be described wrt the subject vehicle's three axes (i.e. pitch, yaw, roll)... $\endgroup$ – Digger Jun 29 '18 at 19:48
  • $\begingroup$ "minimized the danger that could arise due to orbital debris impacts" -- because impact velocity distribution will be higher on the leading end, and retrograde orientation put the crew cabin at the trailing end? $\endgroup$ – Russell Borogove Jun 29 '18 at 20:51
  • $\begingroup$ Yes, debris hits on the engines might be expensive to fix but wouldn't be a safety problem during entry. $\endgroup$ – Organic Marble Jun 29 '18 at 21:54

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