A new global map of Mars offers a fresh perspective on the planet.
The map, released earlier this month, was compiled from 3,000 images taken by the UAE spacecraft, and it shows the red planet in its true light.
“These are all normal colors on Mars,” said Dimitra Atre, a research scientist at the Space Science Center at NYU Abu Dhabi.
The main science goal for Hope, which entered orbit around Mars a little over two years ago, is to study how dust storms and other atmospheric conditions near the surface affect the speed at which Martian air escapes into outer space.
But the orbiter also carries a camera.
When Dr. Atree saw the first image Hope sent, he said, “I was blown away by the quality of the image, which shows the whole disc.” “I’ve never seen Mars like this before.”
Mars maps are nothing new. In the 1890s, American businessman Percival Lowell used his fortune to build the Lowell Observatory in Flagstaff, Arizona, and as he gazed at Mars through a 24-inch telescope, he drew what he thought were artificial channels built by the Martian civilization. (He noticed spoke-like structures on Venus; it was later revealed that he may have inadvertently turned his telescope to a mirror and was looking at the back of his eyeball.)
In the space age, many spacecraft have flown by or entered orbit around Mars.
But earlier orbiters, such as NASA’s Mars Global Surveyor and NASA’s Mars Reconnaissance Orbiter, generally came very close to the surface of Mars, usually on orbits designed to pass over and over a specific location at the same time of day. These images provided increasingly sharp details of the surface, including dunes, gullies, and boulders that rolled down hills.
“These are amazing, beautiful images,” said Dr. Atre. “But you don’t see the whole planet at once.” Lighting conditions that vary from place to place make it difficult to create a single global view.
Lighting conditions are not an issue for other map types. The Global Scanner held an altimeter that bounced the laser beam off the surface. By measuring the time it takes for a pulse of light to travel to a surface and back, the instrument can measure the height of every nook and cranny on the surface. The scientists used the data to create a detailed topographic map.
For a viewer in visible light, the Hubble Space Telescope, which is in Earth orbit, can see one entire side of Mars. Scientists have stitched many of these images together into a global map similar to the new map by the Hope spacecraft.
But Mars, at its closest point, is roughly 34 million miles from Earth, so Hubble’s images lack sharpness. Hope travels around Mars in an elliptical orbit that ranges from 12,400 miles to 27,000 miles above the surface of Mars. This is much higher than the Mars Reconnaissance Orbiter, but much closer than the Hubble.
“We thought, well, we should have an atlas, because we might be able to image Mars over a number of years,” said Dr. Atree. “So we should first have an atlas where we not only map the entire planet, but show how it changes over the course of the Martian year.”
Dr. Atree was able to find photos with similar lighting conditions to tie them together, omitting photos where clouds obscured the surface. The process took months. “It’s very difficult to remove all the boundaries and stuff,” he said.
Dr. Otri said that he and his colleagues are currently writing a scientific paper to describe the algorithm they created. The same method could be applied to other spacecraft visiting other worlds, including the European Space Agency’s Jupiter Icy Moons Explorer or Juice, which launched on Friday.
“These icy moons look very beautiful,” said Dr. Atri. “So we should be able to apply the same method.”
