I love them as well , especially Mars. It is easy to see that it shares similarities with the main riff in the song Black Sabbath .
The riff was created when bassist Geezer Butler began playing a fragment of "Mars" from Gustav Holst's The Planets suite. Inspired, guitarist Tony Iommi returned the next day with the famously dark tritone.
Some even call this tri-tone the birth of " Heavy Metal" , kind of hard to disagree IMO.