Zond 5 splashed down in the Indian Ocean on September 21 after a successful circumlunar flight. The biological passengers — turtles, flies, mealworms, plant seeds — all survived. The turtles lost some weight but were otherwise healthy.

Now let me think carefully about what this means.

The Zond spacecraft is a modified Soyuz — specifically the Soyuz 7K-L1 variant, stripped of the orbital module to reduce weight and configured for the circumlunar trajectory. It cannot enter lunar orbit; it follows a free-return trajectory, swinging around the Moon and coming back to Earth without any powered insertion.

A crewed version of this mission is possible with current Soviet hardware. The Proton rocket that launched Zond 5 is reliable enough. The spacecraft systems worked correctly. The re-entry (into the Indian Ocean, not the planned recovery zone in the Soviet Union, which is a guidance accuracy problem) was survived.

The question is whether the Soviets will fly crew on the next Zond mission, or the one after.

American intelligence has apparently been following this closely. The answer is shaping NASA’s decision about Apollo 8 — whether to accelerate to a lunar orbit mission in December rather than staying in Earth orbit.

Here’s my assessment, for what it’s worth: the Soviets want the manned circumlunar first. It’s the next “first” available to them, since they’ve conceded that a manned landing first is probably impossible given Apollo’s schedule. A manned flyby before Christmas would be a significant propaganda victory.

But their hardware has reliability problems that they can’t fully test before flying crew. Soyuz 1 killed Komarov. The Soyuz program has had subsequent technical issues. Flying crew on the next Zond would be a significant risk acceptance.

I think they’ll do it. I’ve been wrong before.

If they do, and it works, the headlines will read “Soviets reach Moon before Americans.”

The landing is still ours. But the next few months matter enormously.