A new map of Mars from a spacecraft called Hope

A new global map of Mars offers a new perspective on the planet.

The map, released earlier this month, was compiled from 3,000 photos taken by the United Arab Emirates’ Hope spacecraft and shows the red planet in its true light.

“These are all the natural colors of Mars,” said Dimitra Atri, a researcher at the Center for Space Sciences at NYU’s Abu Dhabi campus.

The primary science goal of Hope, which entered Mars orbit just over two years ago, is to study how dust storms and other weather conditions near the surface affect the rate at which Martian air escapes into outer space.

But the orbiter also carries a camera.

When Dr. Atri saw the first image sent back by Hope, “I was just blown away by the quality of the image showing the entire disc,” he said. “I had never seen Mars like this.”

Maps of Mars are nothing new. In 1890, American businessman Percival Lowell used his wealth to build the Lowell Observatory in Flagstaff, Arizona, and while looking at Mars through a 24-inch telescope, he sketched what he believed to be man-made canals built by a Martian civilization. (He observed spoke-like structures on Venus; it was later shown that he may have inadvertently turned his telescope into a mirror and was looking at the back of his own eyeball.)

In the space age, numerous spacecraft have flown past or entered orbit around Mars.

But previous orbiters, such as NASA’s Mars Global Surveyor and Mars Reconnaissance Orbiter, have typically come much closer to the Martian surface, usually in orbits designed to pass over a location repeatedly at the same time of day. These images provide ever sharper surface detail, including sand dunes, gullies and boulders that have rolled down the hills.

“These are amazing, spectacular images,” said Dr. Atri. “But you don’t see the whole planet at once.” Lighting conditions that vary from place to place make it difficult to compile a single global view.

Light conditions are not a problem for other card types. Global Surveyor carried an altimeter that reflected a laser beam from the surface. By measuring the time it takes for the light pulse to travel to the surface and back, the instrument can measure the height of every nook and cranny of the surface. The scientists used the data to make a detailed topographic map.

For visible-light views, the Hubble Space Telescope, in orbit around Earth, can see an entire side of Mars. Scientists have compiled many such images into a global map similar to the new map from the Hope spacecraft.

But Mars, at its closest, is almost 34 million miles from Earth, so Hubble’s images lack sharpness. Hope travels around Mars in an elliptical orbit ranging from 12,400 miles to 27,000 miles above the Martian surface. That’s significantly higher than the Mars Reconnaissance Orbiter, but much closer than Hubble.

“We thought, well, we have to have an atlas because we might be able to photograph Mars over a period of several years,” Dr. Atri said. “So first we need to have an atlas where we can not only map the entire planet, but also show how it changes during the Martian year.”

Dr Atri was able to find images with similar lighting conditions to link them, omitting those where clouds obscured the surface. The process took months. “It’s extremely difficult to remove all the borders and stuff,” he said.

Dr Atri said 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 ice moons look so beautiful,” said Dr. Atri. “So we should be able to apply the same technique.”

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