A new global map of Mars offers a
fresh perspective on the planet.
The map, released earlier this month, was
pieced together from 3,000 pictures taken by the United Arab Emirates’ Hope
spacecraft, and it shows the red planet in its true light.
اضافة اعلان
“These are all natural colors on Mars,”
said Dimitra Atri, a research scientist at the Center for Space Science at NYU
Abu Dhabi.
The main scientific objective of Hope,
which entered orbit around Mars a little more than two years ago, is to study
how dust storms and other weather conditions near the surface affect the speed
at which Martian air leaks into outer space.
But the orbiter also carries a camera.
“I was just blown away by the quality of the image showing the full disk,” he said. “I had never seen Mars like this.”
When Atri saw the first image sent back by
Hope, “I was just blown away by the quality of the image showing the full
disk,” he said. “I had never seen Mars like this.”
Canals, dunes, topographyMaps of Mars are nothing new. In the 1890s,
American businessman Percival Lowell used his wealth to build the Lowell
Observatory in Flagstaff, Arizona, and as he gazed at Mars through a 60-cm
telescope, he sketched what he thought were artificial canals built by a
Martian civilization. (He observed spokelike structures on Venus; it was later
demonstrated that he may have inadvertently turned his telescope into a mirror
and been viewing the back of his own eyeball.)
In the Space Age, numerous spacecraft have
flown past Mars or entered orbit around it.
But previous orbiters, like NASA’s Mars
Global Surveyor and Mars Reconnaissance Orbiter, have generally swooped much
closer to the Martian surface, usually in orbits devised to repeatedly pass
above a given location at the same time of day. Those images have provided increasingly
sharp details of the surface, including sand dunes, gullies, and boulders that
had rolled down hills.
“Those are amazing, spectacular images,”
Atri said. “But you don’t see the whole planet at once.” Lighting conditions
that varied from place to place made it difficult to put together a single,
global view.
Lighting conditions are not a problem for other
types of maps. The Global Surveyor carried an altimeter instrument that bounced
a laser beam off the surface. By measuring the time the pulse of light took to
travel to the surface and back, the instrument could measure the height of
every nook and cranny on the surface. Scientists used the data to make a
detailed topographic map.
Atri was able to find images with similar lighting conditions to stitch together, omitting ones in which clouds obscured the surface. The process took months.
For views in visible light, the Hubble
Space Telescope, in orbit around Earth, can see one entire side of Mars.
Scientists pieced together many such images into a global map similar to the
new map from the Hope spacecraft.
Stitching together a planetBut Mars, at its closest, is nearly 54
million kilometers from Earth, so the Hubble images lack sharpness. Hope
travels around Mars in an elliptical orbit ranging from 19,900km to 43.400km
above the Martian surface. That is considerably higher up than the Mars
Reconnaissance Orbiter, but much closer than Hubble.
“We thought, OK, we should have an atlas,
because we may be able to photograph Mars over a period of several years,” Atri
said. “So we should first have an atlas where we not only map the whole planet,
but we show how it changes throughout the Martian year.”
Atri was able to find images with similar
lighting conditions to stitch together, omitting ones in which clouds obscured
the surface. The process took months. “It is extremely hard to remove all the
boundaries and stuff,” he said.
Atri said that he and his colleagues were
currently writing a scientific paper to describe the algorithm they devised.
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 Friday.
“These icy moons look so pretty,” Atri
said. “So we should be able to apply the same technique.”
Read more Odd and Bizarre
Jordan News
.jpg)
.jpg)
