I've got a full-colour picture looking down the split glans of the telecope/whatever...it has multiple holes between the two flayed flaps, I took it for multiple lenses for this alien 'telescope' for a time...
The film,however, NEVER showed this aparatus from an angle we could SEE these holes...
Perhaps, Ridley is happy he had an artist that could enlarge his vision between canvas and full-sized sculpture...and it is serendipitous that something Giger added to a model on a sound-stage might have sparked Prometheus.
Ridley Scott (1978)..."I LOVE the Space Jockey...but it's going to be twice as expensive to build this telescope..."
HR Giger..."But you muzt!...Ozerwise Jockey make NO sense!...and iz OBVIUZLY not TELESCOPE!..Iz PLANET INZEMINATOR!!!"
...I'm pretty sure THAT's the way it went down.