Actually, it's quite a mystery why this show did not run longer, as it was
very popular in Germany.
Was it because it would have been more expensive to make episodes
next year, when color TV would be introduced in Germany?
Was it because the militaristic nature of the space fleet conflicted with
sensitivities concerning Germany's past?
There has been considerable speculation. There are also parallels
between the series and Star Trek. The budget was tight, so ordinary
objects were used as props. The Captain was in hot water for not
always following orders. It was set in a future where individual nations
on Earth no longer existed.
On the other hand, sexual tension was handled with subtlety in
the show, and it was a minor character - who tended to get shot
down - who was portrayed as a womanizer.
More significantly, there was only one alien race referred to in
the show, and that race was a deadly menace at war with humans.
John Savard