This week a probe was launched into space to detect waste gases emitted on Mars.
A rocket carrying The ExoMars Trace Gas Orbiter (TGO) was launched on Monday. It's hoped that the probe might detect gases emitted by alien organisms on Mars.
It was an absolute gift of a news story: Space, Mars, aliens, methane... The potential for comedy was huge. But what to draw? A number of images popped into my head.
Tempting though it was to draw an alien, it didn't feel right. Too obvious. I liked the toilet door though. It was symbolic of a certain odour.
What if that odour came from an astronaut? What if there was a misunderstanding? I tried it...
I liked it. One astronaut is getting excited about high methane readings, whilst another astronaut - the culprit - is stepping unnoticed out of the gents. Stepping? Floating. They're in zero gravity. I liked that too; shorthand for being in space.
It needed a caption. Some dialogue. I included the word 'Houston' because, again, it's shorthand; Houston = space missions. Even though the ExoMars programme is European and Russian, not American!
One more thing: I wanted the toilet door to be the punchline. So I placed it on the right hand side of the cartoon because it's English and culturally we read from left to right.
That's it! I was nearly there. The spaceship had become cylindrical, perhaps a nod to the film 2001: A Space Odyssey, and I had searched online for images of space stations so I could draw interior details - screens, dials, fastenings and so on on.
I was happy with the final cartoon (see image at top) and shared it widely. Until a Senior Science Advisor at the European Space Agency informed me that methane is odourless; it's the sulphur that often accompanies it that has a scent.
Nevermind, I thought. His comment was sent in jest and I accepted it in that spirit. If I'm going to make a joke, I've got to be able to take a joke. And I took it as a compliment that he had spared the time to write to me and teach me something. That's always good. Besides, my cartoon spaceship would have both methane and sulphur inside it, so it still made sense. Sort of.
I stand by my cartoon. I stand by it whilst waving a printed and bound artistic license in the air and giggling at the thought of farts in space.
Cartoonist and comics creator at Richard Pettitt Art. Studio in Uckfield, East Sussex, England.