NASA's Europa Clipper probe snaps ghostly thermal portrait of Mars en route to Jupiter

NASA's Europa Clipper spacecraft, en route to Jupiter's icy ocean moon Europa, recently captured a ghostly infrared portrait of Mars — a cosmic photo op that helped scientists fine-tune an instrument destined to investigate whether Europa can support life as we know it.

The image, a blurry composite of more than a thousand grayscale snapshots later colorized by scientists, was taken during a precision flyby of Mars on March 1, 2025. At its closest point, the spacecraft skimmed just 550 miles (884 kilometers) above the Martian surface, in a maneuver known as a gravity assist, which used the Red Planet's gravitational pull to slow the spacecraft and adjust its orbit around the sun ahead of a crucial leg of its nearly 2-billion-mile (3.2 billion km) journey to Jupiter.

The brief encounter also served a scientific purpose: It gave the mission team a chance to test the spacecraft's instruments in deep space, including the thermal imager E-THEMIS (short for Europa Thermal Imaging System), which will eventually scan Europa's surface for signs of recent or ongoing geologic activity. Over an 18-minute span on March 1, the instrument took over 1,000 grayscale images — one per second — which began arriving on Earth on May 5, according to a NASA statement.

To confirm the instrument's accuracy, the mission team compared the new infrared imagery with long-term thermal maps of Mars gathered by NASA's Mars Odyssey orbiter, which has been observing the Red Planet since 2001. The Odyssey team even coordinated observations before, during, and after the Europa Clipper flyby to allow for a direct side-by-side comparison, according to the statement.

"We wanted no surprises in these new images," Phil Christensen, a professor of earth and space exploration at Arizona State University who serves as the principal investigator of the E-THEMIS instrument, said in the statement. "The goal was to capture imagery of a planetary body we know extraordinarily well and make sure the dataset looks exactly the way it should, based on 20 years of instruments documenting Mars."

E-THEMIS detects infrared light — essentially heat — allowing scientists to map temperatures across a planetary surface. After the spacecraft reaches the Jupiter system in 2030, these thermal scans will help identify hotspots that could point to recent geologic activity beneath Europa's icy shell, according to the statement.

Infrared imaging will also help pinpoint where Europa's vast subsurface ocean might lie closest to the surface, scientists say. The moon is etched with ridges and fractures, features that scientists suspect result from oceanic forces — like rising water or convection currents — pulling apart the ice from below.

"We want to measure the temperature of those features," Christensen said. If Europa is active, its fractures could be warmer than surrounding ice — especially where the ocean lies near the surface or past eruptions left lingering heat, he added.

The Mars flyby also marked the first full in-flight test of Clipper's radar instrument, which couldn't be tested in its entirety on Earth due to the size of its antennas. Preliminary telemetry suggests the test was successful, with detailed analysis of the data still to come, the statement read.

With the Mars flyby complete, Clipper's next gravity assist will come from Earth in 2026. The spacecraft is expected to enter Jupiter orbit in April 2030, after which it will begin a series of 49 close encounters with Europa that will allow scientists to investigate the moon's life-hosting potential.