NASA’s Mars Odyssey orbiter, launched in 2001, has been orbiting Mars for nearly 23 years and has captured over 1.4 million images of the planet. One of the most significant images captured by Odyssey is that of Olympus Mons, the Solar System’s tallest mountain and volcano.
The image, while not visually impressive, holds valuable information for scientists as they piece together the puzzle of Mars. The spacecraft usually points down at the surface and captures images in long strips, but for this image, it was tilted 90 degrees to capture a horizontal view of Mars’ horizon. This unique perspective provides scientists with a different look at the Martian sky, its clouds, and its dust.
The image shows a blue layer at the bottom, which is dust in Mars’ atmosphere. Above that is a purplish layer where red dust from the planet’s surface is mixed with bluish water ice. The top blue-green layer is where water ice clouds reach 50 km (31 miles) into the sky.
Odyssey’s Thermal Emission Imaging System (THEMIS) camera, an infrared camera, was used to capture this image. THEMIS is designed to sense temperature changes on Mars’ surface and can differentiate between sand, rock, ice, and dust. By pointing at the sky, THEMIS can measure the presence of ice and dust in Mars’ atmosphere.
Odyssey’s first horizontal horizon image was taken in late 2023, and it took engineers three months to get the operation right. The spacecraft had to tilt 90 degrees and maintain a position where the Sun could strike its solar panels. To accomplish this, Mars Odyssey used its thrusters to orient itself so that its antennae pointed away from Earth, preventing communication with Earth during the maneuver.
Odyssey has been a significant success, being the longest continually active mission around another planet. However, careful planning and operation are required to keep the spacecraft operational, as it is solar-powered and has a limited amount of hydrazine fuel for its thrusters. Engineers have to recalculate the amount of fuel remaining after each maneuver, and NASA has stated that the spacecraft has enough fuel to last at least until the end of 2025.
Odyssey can change its orbit, but it’s impossible to calculate exactly how many orbits it has left. However, it has completed over 100,000 orbits in nearly 23 years and is likely to complete several hundred more before its hydrazine runs out.
