I'm all for using the scientific method in most things. As an arts graduate who's engaged to a born scientist, I kind of have to be. Rational argument prevents much unhelpful bickering, and if a wedding must be planned, best leave it to someone who is proficient in Microsoft Project. But using one's relationship as the subject of a scientific experiment is where I draw the line. Which is why I am worried about Dennis Tito's planned mission to Mars.

Mr Tito, a multimillionaire financier and former Nasa rocket scientist, is confident that he can raise a couple of billion dollars for a Mars mission in 2018, and he's looking for a married, male-female couple to crew it. "It's important that they are a tried-and-trusted couple," adds a mission adviser. The chosen crew should have "experience [of] living and working in an isolated, confined environment for an extended period of time, preferably for the full mission duration, but for at least six months".

If the team is looking for a marriage that has stuck together for a long time in trying circumstances, shouldn't it first try out some gay couples who got together in the 1950s? And what makes him think that a mixed-sex pair will be better at bonding? Last week, the explorer James Cracknell and his wife talked to the press about his impending desert trip with his travelling companion Ben Fogle – the first since Cracknell nearly died when he and his bicycle were hit by a truck. The trip, said Cracknell, is about "life moving on for both of us". By "both of us", of course, he meant himself and Mr Fogle, who have seen each other naked, lots.

The space vehicle's bathroom arrangements are also a cause for concern. The trip will require "reliable –but minimalist – accommodations and provisions … that would meet only basic human needs to support metabolic requirements and limited crew comfort allowances", prospective couples are told. Basically, they're talking about a dodgy toilet. And we all know that the couple that wants to stay together should never share No 2s.

Worst of all, though, is the probability that the couple will become completely fed up with each other soon into the 501-day trip. It's hard for any couple that live and work together all the time. What will the Mars pair talk about at the end of a long day, when one has cooked the other a romantic tea of dehydrated space food? That is, if they are allowed to talk at all. New research (by neuroscientists, no less) shows that driving a car while talking is very dangerous, because the parts of the brain that process vision and decision-making are "significantly reduced" when communicating. Not only does this mean that my fiancé is proved right in his hypothesis that we should not talk to each other on long road trips, but also that chatting while in charge of a space shuttle could result in a horrible asteroid collision.

That's more silent motorway journeys for my partner and me, then. But at least we're not going to Mars.

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