Brown tells them that the trip to Mars will take six weeks.  Given that modern estimates place the journey between six and eight months, there’s a certain amount of dramatic licence at play here.

What’s made clear is that the journey to Mars is going to be strictly one way – as even if, by some miracle, they reach their destination they’ll have no water or other supplies for the return journey.  Brown is quite calm about this – he still maintains that Mars is a thriving civilisation, so he no doubt assumes the Martians will be able to supply them with whatever they need.

Although Brown’s actions, reckless in the extreme, position him as the villain of the piece, he’s presented in a reasonable light here.  This isn’t too surprising as later episodes will see him integrated back with the others as they all combine to find a solution to their problems.  Indeed, he’s quite affable to Margaret as he explains about the canals of Mars, not taking offence when she disagrees with his assertion that they prove there must be life on Mars.  Hester Cameron impresses with the two-handed scenes she shares with George Coulouris.

Possibly the most notable part of the episode is the sequence where Henderson attempts to break into the control cabin by exiting the rocket and attempting a spacewalk.  There are several reasons why – firstly, I love the periscope that slowly turns to observe him (I think it’s probably because the notion of a periscope is such a delightfully old fashioned concept).  I also like the way that he loses his grip on a spanner which then goes flying into space.  It was clearly on a piece of wire, but it helps to sell the illusion that he’s in space.

But the main reason why this is so memorable is because the same scene, virtually unchanged, turned up thirteen years later in the Doctor Who story Frontier in Space.  That story was written by Malcolm Hulke, the co-writer of Pathfinders to Mars, so it can hardly have been a coincidence.

The lack of supplies seems to be one of the reasons why the relationship between Henderson and Mary is deepening.  He kisses her again – albeit only on the forehead, remember this is children’s television!

As The Hostage draws to a close, they finally reach Mars.  Whilst the others (now released) are still gently dismissive about Brown’s claims of a great Martian civilisation, it’s obvious that we’ll soon be able to find out for ourselves.  It may have taken three episodes but we’re finally there.