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NASA's Cassini Captures Photos of Saturn's Rings In Unprecedented Detail (voanews.com)
NASA's Cassini probe has captured news images of Saturn's rings in unprecedented detail. The images were captured by the probe in its penultimate mission phase of its mission that includes "20 orbits that dive past the outer edge of the main ring system" before the spacecraft plunges into the planet itself. Interestingly, the rings include what NASA calls "moonlets" embedded in them. VOA News reports: The images are the closest ever taken of Saturn's rings and, according to NASA âoeresolve details as small as 550 meters, which is on the scale of Earth's tallest buildings.â The"ring-grazing" orbits began last November and will continue until the end of April, and in addition to spotting the moonlets, they have given greater clarity to other structures within the rings such as the so-called propeller-like formations. NASA added that Cassini has also provided the "closest-ever" glimpses of two small moons, Daphnis and Pandora. The report via NASA Jet Propulsion Laboratory (JPL) adds: "Some of the structures seen in recent Cassini images have not been visible at this level of detail since the spacecraft arrived at Saturn in mid-2004. At that time, fine details like straw and propellers -- which are caused by clumping ring particles and small, embedded moonlets, respectively -- had never been seen before. (Although propellers were present in Cassini's arrival images, they were actually discovered in later analysis, the following year.) Cassini came a bit closer to the rings during its arrival at Saturn, but the quality of those arrival images (examples: 1, 2, 3) was not as high as in the new views. Those precious few observations only looked out on the backlit side of the rings, and the team chose short exposure times to minimize smearing due to Cassini's fast motion as it vaulted over the ring plane. This resulted in images that were scientifically stunning, but somewhat dark and noisy.
NASA seems to really really love using monochrome imaging systems.
Look, I GET that this is in the outer solar system, and that the sun's light is very pitifully weak out there. I GET that. I understand that they want to gather as much light as is possible in the images.
However, monochrome CCDs dont care what frequency the photons are. As long as they can pass through the forward optics and focus, they will add to the luminosity of the resulting image. That means that dust could be very reflective of IR, or UV light, and it would have the same whiteness. Sure, you could subtract some of that out using special optics for IR and UV, and create some horrid false-color image that does not reflect reality at all, other than artificially showing where there is UV or IR reflectivity, but visible light absorbtion/emission spectra are also very useful for scientific enquiry into such objects.
Why does NASA not at least TRY to get true color images with extended exposure times?
It's been a pet peeve of my for years, and I cant be the only one. I KNOW they can do it, because Voyager took lots of true color images back in the 70s. CCD tech has greatly improved since then.