NASA and ESA join for Mars mission

• NASA's Psyche spacecraft performed a gravity-assist flyby of Mars
• The mission used Mars to calibrate its new multispectral imagers
• Data will ensure accurate imaging of the metal asteroid by 2029

In the vastness of space, a chance encounter became a masterclass in ingenuity. NASA's new Psyche spacecraft, en route to a metal world, met ESA's veteran Mars Express orbiter for a perfectly timed, interplanetary photo opportunity.

A Pit Stop at the Red Planet

NASA's Psyche mission, launched in October 2023, has a singular, ambitious goal: to be the first to explore an asteroid made not of rock or ice, but of metal. Scientists believe its target, a 280-kilometre-wide body in the main asteroid belt also named Psyche, could be the exposed iron core of a planetesimal, an early planetary building block. Studying it could offer an unprecedented look at the heart of a world. But to get there, the spacecraft needed a little help. On May 15, 2026, Psyche performed a crucial gravity-assist flyby of Mars. Hurtling past the planet at over 19,000 kilometres per hour, the spacecraft used Mars's gravity like a slingshot to gain speed and adjust its trajectory, saving precious fuel for its 2029 arrival at the asteroid. This manoeuvre, while primarily for navigation, presented a golden opportunity for the science team.

The Importance of a Well-Tuned Eye

Long interplanetary journeys are the perfect time to test and calibrate a spacecraft's sensitive instruments. For the Psyche mission, this meant powering up its suite of scientific tools, including its multispectral imagers. These twin cameras are designed to capture images in different wavelengths of light, allowing scientists to determine the asteroid's surface composition and geology. To ensure these cameras work perfectly upon arrival, the team needed to test them on a known target. Mars, with its well-documented surface and atmosphere, served as an ideal calibration subject. As Psyche flew by, its imagers, magnetometers, and spectrometers were all gathering data, comparing their measurements against the vast pool of existing information on the Red Planet to fine-tune their performance.

Enter the Veteran Orbiter

This is where the story gets a collaborative twist. As the Psyche team planned their calibration activities, scientists at the European Space Agency (ESA) had an idea. Their Mars Express spacecraft has been orbiting the Red Planet since 2003, providing a wealth of data for over two decades. The ESA team realised that the orbits of the two spacecraft would briefly align, allowing them to observe the same part of the Martian surface at nearly the same time. Mission planners from both NASA and the ESA exchanged trajectory data and meticulously coordinated their schedules. The plan was for Psyche to take a snapshot of Mars and for Mars Express, with its well-understood High Resolution Stereo Camera (HRSC), to provide a companion image of the same region.

One Target, Two Unique Perspectives

The coordinated observation focused on a region called Noachis Terra, one of the oldest known parts of Mars. Despite imaging the same landscape within a two-hour window, the spacecraft produced very different views. Mars Express, orbiting at an altitude of just 6,000 kilometres, captured an inclined view. Meanwhile, Psyche, having already completed its closest approach and receding from the planet, took its image from a distance of about 41,000 kilometres, looking almost straight down. By comparing how each camera captured the brightness and colour of the same ancient craters and dunes, scientists can cross-calibrate Psyche's brand-new imagers against the known, reliable performance of the veteran HRSC. This adds a layer of historical data and confidence, ensuring that the images Psyche eventually sends back from its metallic destination are as accurate as possible.