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Manned launches have always been launched prograde to take advantage of the Earth's rotation velocity boost, and often in order to match the prograde orbit of another spacecraft for rendez-vous.

I wonder if any of the manned orbital launches to date could have reached at least a lower, short-term-stable orbit if launched in a retrograde direction, let's say with an additional 180 degrees inclination, they don't need to be zero-degrees equatorial.

I'm curious if this would have been impossible, or achievable and simply requiring the topping-off existing propellant tanks.

I have read that the launching near the equator gives the rocket more speed, but I wonder if it is at all possible to launch against the rotation.

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  • $\begingroup$ Launches from Vandenberg sometimes go westwards to get a polar orbit. These are military recon launches. The shuttle was always launched towards the East. $\endgroup$ – zeta-band Jan 17 at 18:05
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    $\begingroup$ Related: space.stackexchange.com/q/25849/58 $\endgroup$ – called2voyage Jan 17 at 18:09
  • $\begingroup$ yes, Apollo. All that extra TLI $\Delta v$ $\endgroup$ – JCRM Jan 17 at 18:40
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The “westward penalty” from Kennedy/Canaveral would be about 800 m/s of delta-v, about 8-9% of the total delta-v requirement to orbit. Most crewed launchers intended for LEO to date have not had that much performance in reserve; a shortfall of only 100 m/s from LEO usually means prompt reentry.

Atlas/Mercury and Titan/Gemini could not have managed it. The boosters were completely expended to reach orbit, Gemini had only around 323 m/s of maneuvering delta-v, and that at a very low thrust-to-weight ratio, and Mercury had none.

The low Earth orbit Apollo missions (Apollo 7 and 9) could have reached orbit, and even carried out something like their intended missions.

Apollo 7 was a crewed CSM on a Saturn IB booster. The CSM had something like 2800 m/s available, with a fair thrust-to-weight ratio, and in fact the “mode IV” abort option would use the CSM as a third stage to reach orbit if the S-IVB second stage failed. Apollo 7 did a lot of orbital maneuvering to test the CSM engine, and that would have had to be cut short if it were going to spend that much fuel on ascent, but a sizable portion of the original mission plan could have been carried out in retrograde.

Apollo 9 was a CSM/LM flight to LEO on a Saturn V; if fully fueled, the third stage would have had around 3000 m/s of delta-v capability (needed for translunar flight), so even a much lighter fuel load would suffice to go into retrograde orbit.

I believe any of the Apollo lunar missions could have gone from a retrograde Earth orbit ascent to a lunar flyby without hardware modification, abandoning the LM (or docking and extracting it very quickly) when the S-IVB ran out of fuel and completing the TLI on the CSM’s engine. The delta-v budget to enter lunar orbit and then return to Earth is around 1400 m/s. If the LM wasn’t brought along (as on Apollo 8) and both the S-IVB and CSM were fully fueled, a lunar orbit mission might even have been possible from retrograde LEO.

The space shuttle should have been able to do it if a light payload was carried. My quick-and-dirty spreadsheet estimation says it would carry something like 4 tons to retrograde LEO instead of the 27 tons possible into prograde LEO. Unlike the Saturns, the shuttle did have a West coast launch site, never used, that would have made a retrograde launch practical if it had been needed.

I don’t think the Soyuz or Long March launchers had that sort of performance margin.

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    $\begingroup$ The Space Shuttle was capable of polar orbit with a reasonable payload (the Vandenberg launch site was upgraded to support Shuttle launches for this purpose, but never used), so a retrograde launch is certainly within the realm of possibility. $\endgroup$ – Mark Jan 17 at 21:54
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    $\begingroup$ I'm trying to imagine what would have to change in our laws, regulations, and culture before Cape Canaveral could launch rockets over the heads of the folk in Orlando and Tampa. $\endgroup$ – Solomon Slow Jan 17 at 22:18
  • $\begingroup$ @SolomonSlow hence the need for Vandenberg. $\endgroup$ – Organic Marble Jan 17 at 23:35
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    $\begingroup$ @PearsonArtPhoto Solomon is talking about westward/retrograde launch, you're talking about southerly polar. $\endgroup$ – Russell Borogove Jan 18 at 1:04
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    $\begingroup$ This is true. Technical most polar orbits are slightly retrograde, but... $\endgroup$ – PearsonArtPhoto Jan 18 at 1:07

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