NASA’s Odyssey spacecraft, the longest-running mission to Mars, completed its 100,000th flyby of the Red Planet today, the mission team announced in declaration.
To celebrate the milestone, the space agency released an intricate panorama of Olympus Mons, the tallest volcano in the solar system; Odyssey caught sight of in March. The base of the volcano extends 373 miles (600 kilometers) near the Martian equator, while it rises 17 miles (27 kilometers) into the planet’s thin air. Earlier this month, astronomers discovered fleeting morning frost covers the summit of the volcano for several hours each day, offering new insights into how ice from the poles circulates around the arid world.
In the latest image of the Odyssey volcano, the blue-white band seen grazing on Olympus Mons shows the amount of dust floating in the Martian air when the image was taken, according to NASA. A thin purple coating just above probably indicates a mixture of atmospheric dust with bluish clouds of water ice. The blue-green layer at the top edge of the world marks where the water ice clouds reach about 30 miles (48 kilometers) into the Martian sky, the scientists say.
To capture the latest panorama, scientists ordered Odyssey to slowly rotate so that its camera pointed toward the Martian horizon, capturing views similar to those seen by residents of the International Space Station from Earth.
Related: The giant mountain of Mars, Olympus Mons, may once have been a volcanic island
“Normally we see Olympus Mons from above in narrow strips, but by turning the spacecraft toward the horizon, we can see in a single image just how big it is towering over the landscape,” Jeffrey Plaut, Odyssey project leader at the Jet Propulsion Laboratory (JPL) in California, said in a recent press release. “Not only is the image spectacular, but it also provides us with unique scientific data.”
By taking similar images at different times of the year, scientists can study how the Martian atmosphere changes during the planet’s four seasons, each lasting four to seven months.
Scientists say that the foundations for the latest image began as early as 2008, when another NASA mission named Phoenix landed on Mars. When Odyssey, which served as a communication link between the lander and Earth, pointed its antenna at the lander, scientists noticed that its camera was able to observe the Martian horizon.
“We just decided to turn on the camera and see what it looks like,” said Steve Sanders, who serves as an Odyssey spacecraft engineer at Lockheed Martin Space in Denver, Colorado. “Based on these experiments, we designed a sequence that holds [the camera’s] field of view centered on the horizon as we orbit the planet.”
The Odyssey mission was launched in April 2001 and is managed by JPL. It was NASA’s first successful mission to Mars after a pair of failures two years earlier. In 1998, allegedly the Mars Climate Orbiter burned down in the Martian atmosphere after mission engineers swapped the translations between the two measurement systems. A year later, the Mars Polar Lander crashed into the Martian surface for his the engine suddenly shuts off before touching. The Odyssey was therefore widely seen as a mission of redemption.
Odyssey slipped into orbit around Mars in October 2001 and has since revealed previously hidden reservoirs of water ice just below the planet’s surface that may be within reach of future Mars astronauts. The probe also mapped vast swathes of the planet’s surface, including its craters, which helped astronomers decode the history of Mars.
The recent milestone of 100,000 orbits means it has traveled more than 1.4 billion miles (2.2 billion kilometers). The solar-powered spacecraft has no fuel gauge, so the mission team relies on its math skills to estimate the remaining fuel that keeps the 23-year-old mission going. “Physics does a lot of the hard work for us,” Sanders said. “But they are subtleties that we have to master over and over again.
Recent calculations suggest that Odyssey has about 9 pounds (4 kilograms) of propellant left, enough to sustain its original mission until the end of 2025.
“Sustaining a mission for that long while maintaining a historic timeline of science planning and execution—and innovative engineering practices—requires careful monitoring,” said Joseph Hunt, Odyssey project manager at JPL. “We look forward to collecting more great science in the coming years.”