Skip to main content

Rebooted Mars Express instrument peers inside martian moon Phobos

A nearly 20-year-old instrument on the European Space Agency (ESA)’s Mars Express orbiter recently received a software upgrade which has enabled it to study the martian moon Phobos in greater detail than ever before. The Mars Advanced Radar for Subsurface and Ionosphere Sounding or MARSIS instrument was originally designed to study the interior of Mars, but in a recent flyby, it was able to gather close-up data on one of Mars’s two moons.

MARSIS was updated from its Windows 98-based software earlier this summer, allowing it to collect and process data more efficiently. That let it take a deep look at Phobos. “We didn’t know if this was possible,” said ESA’s Simon Wood, who oversaw the upload of the new software, in a statement. “The team tested a few different variations of the software, with the final, successful tweaks uploaded to the spacecraft just hours before the flyby.”

Mars Express HRSC image of Phobos, taken on 7 March 2010.
Mars Express HRSC image of Phobos, taken on 7 March 2010. ESA/DLR/FU Berlin (G. Neukum)

Mars Express made its flyby of Phobos on 23 September, with the craft coming within around 50 miles of the moon. The MARSIS instrument was designed to operate from a much greater distance, as it typically passes over 150 miles from Mars.

“During this flyby, we used MARSIS to study Phobos from as close as 83 km,” said Andrea Cicchetti from the MARSIS team at the Italian National Institute for Astrophysics. “Getting closer allows us to study its structure in more detail and identify important features we would never have been able to see from further away. In future, we are confident we could use MARSIS from closer than 40 km. The orbit of Mars Express has been fine-tuned to get us as close to Phobos as possible during a handful of flybys between 2023 and 2025, which will give us great opportunities to try.”

The MARSIS instrument on ESA's Mars Express spacecraft uses its recently upgraded software to peer beneath the surface of the martian moon Phobos.
The MARSIS instrument on ESA’s Mars Express spacecraft uses its recently upgraded software to peer beneath the surface of the martian moon Phobos. INAF - Istituto Nazionale di Astrofisica

The data collected by MARSIS should help reveal the interior structure of Phobos. The researchers are still analyzing the data, but according to Cicchetti, they have already seen indications of previously unknown features beneath the surface. Understanding the moon’s structure can help to answer questions such as how Mars’s moon formed — whether they were asteroids which got too close to the planet and were captured by its gravity or chunks of the planet  blown off by an impact.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
A solar eruption was detected on Earth, the moon, and even Mars
A coronal mass ejection as seen by SOHO on 28 October 2021. This event is an example of a rare ‘ground level enhancement’. During these events, particles from the Sun are energetic enough to pass through the magnetic bubble that surrounds Earth and protects us from less energetic solar outbursts. This was only the 73rd ground level enhancement since records began in the 1940s, and none have been recorded since.

When you think of the dangers of the sun, your mind most likely turns to the global threat of climate change. But the sun is active and difficult to predict, and it doesn't just pump out a steady stream of heat and radiation -- sometimes it gives off huge ejections that can have serious effects on Earth. Scientists recently reported on one such solar event that was detectable not only on Earth, but also on the moon and Mars.

The solar event, called a coronal mass ejection, occurred on October 28, 2021. A significant amount of plasma erupted from the sun's corona, spreading out as it traveled through the solar system to the extent that it reached both Earth and Mars even when they were on opposite sides of the sun, 150 million miles apart. The event was imaged by various spacecraft including NASA and the European Space Agency (ESA)'s SOHO solar mission. To see an animation of the coronal mass ejection, you can head over the ESA's website.

Read more
See seasonal changes on Mars in two stunning images from MAVEN
mars maven ultraviolet seasons orbit16863 apo ladfit localff png

The planets in our solar system experience seasons because of the way that they are tilted in their orbits, so one hemisphere is facing the sun more often at some times of year than others. However, there's another factor which also affects weather and conditions on some planets, which is their position in their orbit around the sun. Earth has a relatively circular orbit, so the differences caused by it being slightly closer or further from the sun at different points are minimal. But Mars's orbit is much more eccentric or oval-shaped than Earth's, meaning conditions differ based on when the planet is closer to the sun.

That effect is illustrated in two images of Mars recently released by NASA, which show the planet at its closest and furthest point from the sun. Taken by a Mars orbiter called MAVEN, or Mars Atmosphere and Volatile EvolutioN, the images were taken six months apart in July 2022 and January 2023 respectively, showing how the environment of the planet changes with both season and the planet's orbit.

Read more
See a postcard from Mars taken by the Curiosity rover
NASA’s Curiosity Mars rover used its black-and-white navigation cameras to capture panoramas of “Marker Band Valley” at two times of day on April 8. Color was added to a combination of both panoramas for an artistic interpretation of the scene.

Today, you can enjoy a stunning new view of Mars, thanks to a postcard from the Gale Crater taken by the Curiosity rover. The image combines two different views of the same area and is colorized to show off the undulating martian landscape in a region called the Marker Band Valley.

The image, shared by NASA's Jet Propulsion Laboratory (JPL), shows the back of the rover and views of the tire tracks it has left across the martian surface as it has driven. The view on the left side of the image was taken in the morning of April 8, at 9:20 a.m. local Mars time, while the image on the right side was taken on the same day but in the evening, at 3:40 p.m. local Mars time. The two images have been blended together to show how the landscape looks different throughout the day.

Read more