If AstroBot cannot win any row with the astronaut it places when exploiting the crater, where does that astronaut go?

Question

Accepted Answer

The designer says it probably goes to the slot the arrow on the solo card points to, though the case is rare. The rules are otherwise silent, and one player suggested the first vacant slot, which the designer did not repeat.

Shackleton Base: A Journey to the Moon

If AstroBot cannot win any row with the astronaut it places when exploiting the crater, where does that astronaut go?