And it’s a whopper. It looks for all the world not like an alien world, but rather like a majestic sunset back here on Earth, from nearly anywhere where there are overlooks at hills and mountains on the Home Planet—except it’s blue hued rather than red.
The breathtaking color images were captured by Curiosity’s Mast mounted color camera in April, but only just recently transmitted back across the vast gulf of hundreds of millions of miles (kilometers) of interplanetary space.
“The sun dips to a Martian horizon in a blue-tinged sky in images sent home to Earth this week,” NASA officials said in a statement.
The one-ton robot’s Mast Camera (Mastcam) recorded the dramatic blue sunset during an evening of skywatching on April 15, 2015, or Sol 956, of her work investigating the Red Planet.
A still image is shown above. A four-image sequence combined into a GIF animation is shown below.
The quartet of sunset images for the animation were taken over a span of just 6 minutes, 51 seconds and are the rover’s first color images of a sunset from Curiosity.
The Mastcam images were taken by the robot’s wider angle left eye 34 mm color camera, built by Malin Space Science Systems, based in San Diego, Calif.
“Mastcam sees color very similarly to what human eyes see, although it is actually a little less sensitive to blue than people are,” according to the science team. They have been color calibrated and white-balanced to remove camera artifacts.
Currently, Curiosity is investigating the very picturesque foothills of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky and dominates the center of the Gale Crater landing site, where she safely touched down on Aug. 5, 2012.
Mount Sharp is comprised of sedimentary rock layers that record the history of ancient Martian environments and is the primary destination of the mission.
The rover is examining how environmental conditions changed over billions of years, and how their potential to support microbial life changed in Mars’ early history.
For a daylight view of this area showing Mount Sharp, see our photo mosaic herein created by the image processing team of Marco Di Lorenzo and Ken Kremer.
The sundown images were taken in between dust storms, although some dust remained suspended high in the very thin Martian atmosphere, which is less than 1 percent as thick as Earth’s.
What is the source of the colors?
“The colors come from the fact that the very fine dust is the right size so that blue light penetrates the atmosphere slightly more efficiently,” said Mark Lemmon of Texas A&M University, College Station, the Curiosity science-team member who planned the observations.
“When the blue light scatters off the dust, it stays closer to the direction of the sun than light of other colors does. The rest of the sky is yellow to orange, as yellow and red light scatter all over the sky instead of being absorbed or staying close to the sun.”
Here is the matching daylight view of the same Martian landscape:
We all know from living on Earth that colors are much more dramatic during sunsets. The same is true on Mars.
“Martian sunsets make the blue near the sun’s part of the sky much more prominent, while normal daylight makes the rusty color of the dust more prominent.”
“Dust in the Martian atmosphere has fine particles that permit blue light to penetrate the atmosphere more efficiently than longer-wavelength colors. That causes the blue colors in the mixed light coming from the sun to stay closer to sun’s part of the sky, compared to the wider scattering of yellow and red colors. The effect is most pronounced near sunset, when light from the sun passes through a longer path in the atmosphere than it does at mid-day.”
Besides providing beautifully pleasant images, sunset observations are also useful scientifically because researchers say they can use the images to “assess the vertical distribution of dust in the atmosphere.”
Coincidentally, at virtually the same time, as she was snapping these gorgeous sunset imagery, Curiosity had just passed the 10 kilometers (6.214 miles) mark on Sol 957 (April 16) for total driving since her August 2012 touchdown.
Curiosity was making tracks and science observations while on the move and heading southward seeking science targets at the mountain foothills.
“We’ve not only been making tracks, but also making important observations to characterize rocks we’re passing, and some farther to the south at selected viewpoints,” said John Grant of the National Air and Space Museum, Washington, in a statement. Grant is a Curiosity science team member who has recently served as the team’s long-term planner.
For the past six months, Curiosity has been investigating an enticing area called the “Pahrump Hills” outcrop at the base of Mount Sharp, including most recently at a beautiful patch of water-altered mineral veins she discovered at the “Garden City” outcrop in late-March, on her epic trek now around the foothills of Mount Sharp, as reported here.
The six-wheeled rover is now investigating a hillside area and a valley at the mountain base called Mount Shields, to see how it all fits in to the context of Gale Crater.
She has taken some 239,900 images over 985 Sols of exploration.
Stay tuned here for continuing updates from Mars and throughout our Solar System!
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