The Real Reason why Spirit Only Sees Red

use_compress writes To produce a color photograph, the rover's panoramic camera takes three black-and-white images of a scene, once with a red filter, once with a green filter and once with a blue filter. Each is then tinted with the color of the filter, and the three are combined into a color image. In assembling the Spirit photographs, however, the scientists used an image taken with an infrared filter, not the red filter (NYTimes, Free Registration Required). Some blue pigments like the cobalt in the rover color chip also emit this longer-wavelength light, which is not visible to the human eye."

Was in New Scientist a week or so ago

[Space cowboy]

The reason being that the science gets better results using th e IR filter than if the red filter were used... At the moment, despite great public interest, the science is more important... that IS what it's there for....

Simon

Versatility

[Detritus]

Instead of being limited to some fixed approximations of red, green, and blue, they can use a larger set of filters that are tailored for various science objectives.

The human eye's color vision is a poor scientific instrument. It can be easily fooled.

Re:Why b/w & filter?

[MCZapf]

Fake it?? It's still a real picture! The landscape isn't moving, so it doesn't really matter if the camera captures each color in succession, rather than all at once, as in most cameras. It's a tradeoff; it takes longer to capture all the data, but you get a higher resolution full-color image as a result.

Re:Why don't they...

[v01d]

On top of that... 3 colors multiplied by 2 megapixels = the equivalent of 6 'consumer' megapixels.

That was his point. The common 4 megapixel cameras are actually only 1.3 per color.

Regardless, megapixel count is hardly the most important aspect of a digital camera. The lens matters far more, as does the spacing and quality of the pixels. Really, NASA has a very interesting article on the topic.

Slightly off-topic: How bright is it at Mars noon?

[RetiredMidn]

Given that we're having so much trouble figuring out what the human eye would see (w.r.t. color), I probably shouldn't even bother to ask, but does anyone know how bright Martian daylight would appear to the naked eye? Insufficiently bright for sunglasses, for example? How (un)comfortable would it be looking at the sun?

I know the human eye is fairly adaptive in this regard, but I'm curious about the qualitative answer to this question. (Quantitative answers expressed in lumens or whatever won't quite do it for me.)

Re:Why don't they release the RGB too?

[robsimmon]

I would guess (based on my experience with other NASA data archives) that the full scientific data are not being released until they've been calibrated, at which point they'll probably end up in the Planetary Data System [nasa.gov] It's also possible that the Principle Investigators (who are affiliated with Cornell, not NASA) have exclusive use of the data for some period of time. Scientists are often very reluctant to share data until they're happy with it. Whether this is good public policy (since the data was all paid for by the US public) or good science is open to debate, but it's certainly not a conspiracy.

In the case of the more dramatic images, Public Affairs is almost certainly embargoing the images so the press release will (in theory) have more impact. If you really want the data you can always try a Freedom of Information Act [nasa.gov] request.

Re:Why don't they release the RGB too?

[mlyle]

No conspiracy theory here, just I think it's bad PAO PR to embargo. Me putting together some images on my site is not going to lessen the impact when they hold their press conference. But my inability to get the imagery annoys me and the rest of the hobbyist community.

Sure, PDS is the authentic source for mission scientific data, but would it really be hard to throw us a bone with a few technical numbers? It's getting pushed occasionally for some of the imagery with Maestro updates-- why can't they just have a few lines on the website with the engineering data.

They should make up their minds. The degree of transparency they had talked about being in place before the mission is simply not there.

Re:Was in New Scientist a week or so ago

[SnowZero]

And it was on NASA's site almost two weeks ago:
Revealing Mars' True Colors: Part One [nasa.gov]
Revealing Mars' True Colors: Part Two [nasa.gov]
Nothing to see here, take off the tinfoil hat.