The 23-year-old orbiter is capturing images that offer panoramic views of the Red Planet, similar to what astronauts on the International Space Station see on Earth.

Orbital apparatus NASA Mars Odyssey 2001 This year marks 100,000 orbits around Mars, providing valuable data and stunning images, like this recent photo of the Olympus Mountain horizon. Led by NASA’s Jet Propulsion Laboratory, the mission uses innovative techniques to capture unique perspectives of the Martian surface and atmosphere, aiding scientific understanding and future research.

Celebrating a major milestone: 100,000 Mars orbits

NASA’s longest-lived Mars rover recently reached a new milestone. On June 30, it completed 100,000 trips around the Red Planet since its launch 23 years ago. During that time, the 2001 Mars Odyssey orbiter mapped minerals and ice on the Martian surface, identified landing sites for future missions, and transmitted data back to Earth from NASA’s rovers and landers.

Scientists recently used the orbiter’s camera to capture a stunning new image of Mount Olympus, the tallest volcano in the Solar System. The image is part of the Odyssey team’s ongoing efforts to create a high-altitude view of the planet’s horizon. (The first of these images is due out in late 2023.) Similar to the image seen when astronauts on Earth board the International Space Station (ISS), the image will allow scientists to learn more about clouds and airborne dust on Mars.

The latest image of the horizon, taken on March 11, shows Mount Olympus in all its glory. The shield volcano rises to a height of 17 miles (27 kilometers) with its base extending 373 miles (600 kilometers).

“Normally we see Mount Olympus in narrow bands from above, but when we turn the spacecraft toward the horizon, we can see in a single image just how large it is on the landscape,” said Jeffrey Plaut, Odyssey project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Southern California, who manages the mission. “The imagery is not only spectacular, it also provides us with unique scientific data.”

In addition to a still image of clouds and dust, such images taken over multiple seasons could provide scientists with a more detailed understanding of the Martian atmosphere.

The bluish-white line at the base of the atmosphere shows how much dust was in the region in early fall, when dust storms typically begin. The red layer above is likely the result of the planet’s red dust mixing with blue water-ice clouds. Finally, a blue-green layer can be seen at the top of the image, where water ice clouds reach about 31 miles (50 kilometers) into the sky.

How they took the photos

The orbiter, named after Arthur C. Clarke’s classic science fiction novel 2001: A Space Odyssey, captured the scene using a heat-sensitive camera called the Thermal Emission Imaging System, or THEMIS, built and operated by Arizona State University in Tempe. But photographing the horizon requires extra planning, since the camera is designed to look down at the surface.

By firing thrusters around the spacecraft, Odysseus can direct THEMIS to different areas of the surface, or even slowly turn over to view Mars’ tiny moons Phobos and Deimos.

The latest image of the horizon was conceived as an experiment years ago during the landings of NASA’s Phoenix mission in 2008 and the Curiosity rover in 2012. Like other Mars landings before and after those missions, Odyssey played a key role in transferring data as a spacecraft body to the surface.

To transmit vital engineering data back to Earth, Odyssey’s antenna had to be pointed toward the incoming spacecraft and landing ellipse. (See image below.) Scientists were intrigued when they realized that the positioning of Odyssey’s antenna for the mission meant that THEMIS would point toward the planet’s horizon.

“We decided to turn on the camera and see what it looked like,” said Steve Sanders, Odyssey spacecraft operations engineer at Lockheed Martin Space in Denver. Lockheed Martin built Odyssey and helps run day-to-day operations with mission managers at JPL. “Based on those experiments, we developed an array that keeps THEMIS’s field of view centered on the horizon while it’s in orbit around the planet.”

The secret of long space travel

What’s the secret behind Odyssey, the longest continuously active mission in orbit around a planet other than Earth?

“The physics does most of the heavy lifting for us,” Sanders said. “But these are subtleties that we have to work through over and over again.”

These variables include fuel, solar energy, and temperature. In order for Odyssey to conserve fuel (hydrazine gas), engineers must calculate how much is left, as there is no fuel level sensor on the spacecraft. Odyssey relies on solar energy to power its instruments and electronics. This power changes when the spacecraft disappears behind Mars about 15 minutes after entering orbit. All Odyssey instruments need to stabilize temperature in order to function properly.

“Ensuring a mission this long while maintaining the historic scale and innovative engineering practices of science planning and execution requires careful monitoring,” said Odyssey project manager Joseph Hunt of JPL. “We look forward to collecting even greater science in the years to come.”