This has always been a favourite of mine. As a child it's hard not to get swept away with the pictures it puts into your mind. Even without knowing about tritones there is something in this piece of music that simply reeks of evil intent. It's in the slow build up, in that great view from the distance where you can see something inevitable and overwhelming coming for you and you cannot get out of the way. It hits. It obliterates. It destroys and then it passes straight over what once was you in a rumble of timpani and brass.
The rasping howl of the Mellotron brass suits this 5/4 metred piece perfectly. A common criticism of the Mk II brass section is the combination of sounds it uses. It has a trombone and a trumpet in it, after which the natural addition would be a French horn. Unfortunately the decision was taken to make that third instrument a saxophone, which has a low end reedy buzz that makes it impossible to play anything sweetly on it at all. It's always going to be an overwhelmingly discordant sound and finds a home par excellence in this piece. The fast viola runs were all played at half speed and wound up to full speed afterwards. The gongs at the start of the piece (I think of it as the point of invasion) also come from a Mellotron, and from one of the weirdest standard sound combinations around - a tape set of marimbas is finished off at the bottom end by a series of half a dozen gongs sounds ranging from the small and tinny up to the full J Arthur Rank.
Fans of YouTube may be interested in watching Frank Stickle's photo montage of his restoration of a Mellotron M400, for which he used Mars as his soundtrack.
I have half a mind to (some day) record the whole of the Planets in this way, but I am aware that rather a lot of other people have done the same and am not entirely sure that it's going to be a game that is worth the candle. We'll see.
Instrumentation: Mellotron M400 Playing