Why did Teddy Sanders say Ares IV would launch in 5 years?

Question

In both the movie and the novel, when Venkat (Vincent) Kapoor is trying to persuade Teddy Sanders to allow satellite imagery of the Ares 3 site, Sanders says that Ares 4 wouldn't launch for another five years.

Every other reference I have been able to find says that Ares 4 would be four years after Ares 3. Given the recent 'death' of Watney, Sanders would presumably be up-to-date on the Ares missions. If the Ares 4 mission had been delayed because of to Watney's death, there would presumably be a later reference, if only to note that Ares 4 was back on the original schedule so they could rescue Watney. A Martian year is almost two Earth years, so it isn't a difference in which planet's years are being referred to.

Yet this line has lasted from the pre-publish version of the story, into the printed version, and survived intact in the movie.

Why would Sanders have a different launch date?

Answer 1

Exaggeration for emphasis

There are no direct comments by writer Andy Weir or any of the creative staff behind the film as to why Sanders chose to say "5 years".

However, note that Kapoor and Sanders were having quite a heated discussion. From the novel:

"A year?" Venkat said, rising to his feet. "That's ludicrous. We can't wait a year for this."

"Why not? Ares 4 won't even launch for another 5 years. Plenty of time."

Venkat took a deep breath and thought for a moment.

In the heat of the moment, it seems that Sanders rounded 4 years to 5. Also, Sanders was emphasizing the amount of time that needs to pass before the Ares 4 launch, and rounding 4 to 5 helps him accomplish this.