New Emirates Mars Mission observations hint at the origins of Mars’ mysterious moon 

A striking view of Mars and its smallest moon, Deimos. This composite was created from several images taken by the EXI instrument aboard the Emirates Mars Mission when it traveled within about 100 km of Deimos. Credit: Emirates Mars Mission

The Emirates Mars Mission (EMM), the first interplanetary exploration undertaken by an Arab nation, has unveiled a series of groundbreaking observations of Mars’ smaller moon, Deimos. The observations, shared during a special session at the European Geosciences Union General Assembly (EGU23) in Vienna, used all three of the mission’s science instruments (EMUS, EMIRS and EXI) to reveal new details of Mars’ most mysterious moon and where it came from, as well as the Red Planet’s larger moon, Phobos.  

The results provide new insights into Deimos’ composition and structure, as well as challenge the long-standing theory that Mars’ moons are captured asteroids, pointing instead to a planetary origin. The observations and images also reveal, for the first time, regions on the far side of Deimos whose composition has not been previously investigated.  

“We are unsure of the origins of both Phobos and Deimos,” said Hessa AlMatroushi, EMM science lead and senior manager of the Earth and Planetary Science Section at Mohammed Bin Rashid Space Centre (MBRSC), United Arab Emirates. “One long-standing theory is that they are captured asteroids, but there are unresolved questions about their composition. How exactly they came to be in their current orbits is also an active area of study, and so any new information we can gain on the two moons, especially the more rarely observed Deimos, has the potential to unlock new understanding of Mars’ satellites.”  

Evidence of a planetary origin 

Christopher Edwards, the EMIRS instrument scientist and an associate professor in the Department of Astronomy and Planetary Science at Northern Arizona University, presented results from the EMIRS instrument, which measures wavelengths in the thermal infrared. The preliminary analyses suggest that the surface of Deimos is rough at small scales and blanketed in fine regolith material, similar to Phobos and Earth’s Moon. The data corroborate the interpretation that both of Mars’ moons are composed of dark, volcanic rock consistent with the Red Planet’s composition.  

“The findings to date suggest that both of Mars’ satellites may have formed from debris left over from an impact on Mars,” Edwards said. “These early findings are exciting and have big implications for understanding the formation of moons in our solar system. Differentiating between the captured asteroid and coalesced Mars debris hypotheses is something to which EMM is well positioned to make significant contributions.” 

Other new measurements include those from EMUS, a spectrometer that measures extreme and far ultraviolet wavelengths. The spectrum of reflected sunlight measured from Deimos was found to be flat and featureless, with no strong signatures of carbon minerals or organic materials, according to Justin Deighan, EMM deputy science lead and a research scientist at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder.  

“These findings suggest that Deimos may not be a D-type asteroid, the kind we’d expect if Mars’ gravity had captured an asteroid into orbit,” said Deighan, science lead for the instrument. “Thanks to the orbiter, named ‘Hope’ (Al Amal in Arabic), we expect to build a better understanding of the origins and evolution of both Phobos and Deimos and to advance our fundamental understanding of these two moons of Mars.” 

Edwards and his NAU team have done significant research on the Red Planet. Under Edwards’ supervision the team at NAU supports several aspects of the Emirates Mars Mission. In Edwards’ role as instrument scientist for the Emirates Mars Infrared Spectrometer, he supports the links between engineering and science, ensuring the instrument is well-calibrated and operations and observations are carried out as planned. In addition, the team at NAU, including staff members Nathan Smith, Kezman Saboi and Jagoda Janiszewska, carries out instrument operations, science data processing and archiving as well as project management. Postdoctoral scholar Christopher Haberle and graduate student Laura Lee support instrument health and telemetry monitoring and some aspects of data processing pipeline improvement, while postdoctoral scholar Aurelien Stcherbinine and graduate student Chris Wolfe, in addition to others, carry out scientific investigations that rely on EMIRS data but also data generated from the other EMM instruments. The team at NAU collaborates deeply with Emirati scientists and engineers along with instrument partners at Arizona State University. 

Edwards is also part of another mission, led by the Japanese Aerospace Exploration Agency, to explore the two moons of Mars.  

Images from EMM’s third instrument, EXI, which measures visible and ultraviolet wavelengths, revealed an unexpectedly smooth surface on the far side of Deimos. This is the closest flyby since Viking 2, providing an exciting opportunity to further investigate this little-studied moon, which is barely 12 kilometers (7.5 miles) across.  

The scientists presented new, high-resolution images taken during flybys that passed within about 60 miles of the moon. EMM also made the first observations in the extreme and far ultraviolet range of the spectrum and the first well-resolved hyperspectral data of Deimos in the thermal infrared range. It is expected that additional observations during EMM’s Deimos campaign will further clarify the moon’s origin. 

A unique knowledge partnership 

EMM is part of a long-term, integrated effort to create economic opportunity through leadership in space science, research and exploration. EMM is the culmination of a unique knowledge transfer and technical development effort started in 2006, which has seen Emirati engineers working with partners around the world to develop spacecraft design, engineering and manufacturing capabilities, as well as building a dynamic science community around that effort. 

EMM was developed by joint teams from MBRSC and LASP using facilities based at the University of Colorado Boulder, where more than 150 engineers and scientists have been involved in the mission’s development and scientific discoveries. LASP, Arizona State University/Northern Arizona University and the Space Sciences Lab at the University of California, Berkeley contributed instruments to this partnership. 

Coinciding with the release of the new imagery, the UAE Space Agency, which funds and operates EMM, also announced the mission will be extended into 2024. “The remarkable performance of the Mars Hope probe has supported a whole range of new observations in addition to meeting our originally stated science mission goals,” said UAE Space Agency Chair Sarah Al Amiri. “In the circumstances, Hope exceeding all expectations, we are extending the Emirates Mars Mission for a further year.” 

Read more about Edwards work with the Emirates Mars Mission:

NAU planetary scientist collaborates on inaugural Mars mission launched by Arab world

Emirates Mars Mission to reach red planet on Feb. 9 with instrument co-designed by NAU planetary scientist

Top photo: A striking view of Mars and its smallest moon, Deimos. This composite was created from several images taken by the EXI instrument aboard the Emirates Mars Mission when it traveled within about 100 km of Deimos. Credit: Emirates Mars Mission

NAU Communications