One thing that I’ve been wondering ever since Curiosity landed on Mars is why the cameras on the rover aren’t more sophisticated. Mike Ravine, project manager for Curiosity, explains that the choice for 2MP cameras was because the camera specifications were fixed as far back as 2004:
We developed all four cameras around a common architecture so the choice of sensor was hedged across all of them. We wanted to be able to capture high frame rates, particularly with the descent camera.’ he explains. MARDI, the downwards-pointing ‘descent camera’ had just a two-minute descent to the planet’s surface, so a high frame rate was essential. The KAI-2020 chip was the smallest Kodak made capable of 720p HD video. ‘We also looked at a 4MP sensor but it would have run around half as fast. And the state of CMOS sensors wasn’t credible in 2004. They’re an interesting option now, but they weren’t then.
Another factor was that the same sensor had to meet the needs of four different cameras (MAHLI, the two Mastcams and MARDI, the camera tasked with capturing the rover’s descent to the planets’ surface). ‘Everything in a project like this is sensitive to price and risk, both real and perceived. The cameras differ in terms of their optics, but by building them around a single platform, we didn’t have to re-test and qualify each of them separately. This makes them more dependable and less expensive than if you have to do it four times.
In case you’re wondering where exactly on Mars the rover Curiosity landed, check out this post by Alexis Madrigal.