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Examining the Martian Moons
The Mars-moon Exploration with GAmma rays and NEutrons (MEGANE) spectroscopy instrument will provide vital information on the composition of the Martian moons, Phobos and Deimos.
MEGANE
About the Instrument
Instrument Type
Gamma-Ray and Neutron
The Martian Moons eXploration (MMX) mission is being developed by the Japan Aerospace Exploration Agency (JAXA). The MMX spacecraft will visit the Martian moon Phobos, land on the surface, collect a surface sample, and then deliver that sample to Earth. On behalf of NASA, APL is leading and building one of the spacecraft’s science instruments: a gamma-ray and neutron spectrometer named MEGANE (pronounced “meh-gah-nay”) that will measure the elemental composition of Phobos. MEGANE’s compositional measurements will provide key information to help determine whether Phobos is a captured asteroid or the result of a larger body hitting Mars.
MEGANE consists of a gamma-ray spectrometer (GRS) and a neutron spectrometer (NS). The GRS uses a high-purity germanium sensor designed and built in partnership with Lawrence Livermore National Laboratory, and is the state-of-the-art technology for achieving high-sensitivity gamma-ray spectral measurements. The NS uses two helium-3 gas proportional sensors to measure neutrons in three broad energy ranges. MEGANE builds on experience from the gamma-ray and neutron spectrometer (GRNS) on NASA’s MESSENGER mission to the planet Mercury and will utilize many aspects of the Psyche GRNS, developed for NASA’s Psyche mission.
Learn more about the different components of MEGANE below. Click the images to view larger versions.
All photos: NASA/JAXA/Johns Hopkins APL/Ed Whitman
Neutron Spectrometer
The neutron spectrometer on the MEGANE instrument has sensors filled with an isotope of helium gas that will detect cosmic-ray-generated neutrons emitted by Phobos to provide composition information regarding Phobos’ surface.
Gamma-Ray Spectrometer
The gamma-ray spectrometer sensor on the MEGANE instrument contains a high-purity germanium crystal to detect gamma rays that will reveal the elemental composition of Phobos.
Data Processing Unit
The MEGANE Data Processing Unit serves as the electronics “brain” for MEGANE. It operates the sensors by processing sensor commands and then passes the sensor data to the MMX spacecraft for transmittal to Earth.
Mars-Bound Johns Hopkins APL Instrument to Provide New Look at Martian Moons Oct 19, 2026
The APL-developed MEGANE spectrometer will help scientists investigate the origins of the Red Planet’s small potato-shaped moons, Phobos and Deimos.
NASA Delivers Science Instrument to JAXA’s Martian Moons Mission Mar 18, 2024
Built by Johns Hopkins APL in collaboration with Lawrence Livermore National Laboratory, the gamma-ray and neutron spectrometer instrument called MEGANE reached the Japanese spacecraft manufacturer last week for final testing and for integration with the Japan Aerospace Exploration Agency’s Martian Moons Explorer mission spacecraft, on which it will play a significant role in determining the origin of Mars’ moons Phobos and Deimos.
NASA Taps Two Johns Hopkins APL Scientists for International Mission to Martian Moons Apr 21, 2023
APL’s Olivier Barnouin and Terik Daly are joining the Science Working Team for the Japan Aerospace Exploration Agency’s Martian Moons eXploration mission as NASA-supported participating scientists.
MEGANE Instrument Test Model Goes to Japan for Physical Tests and Design Review Dec 16, 2020
The Johns Hopkins APL team building the MEGANE spectrometer for Japan’s MMX mission to the Martian moons recently shipped a test model of the instrument. The model will determine how well the instrument fits in the spacecraft design.
Mars-Bound Johns Hopkins APL Spectrometer Passes Major Milestone Jun 9, 2020
The team at Johns Hopkins APL designing the gamma-ray and neutron spectrometer instrument for the Japan-led Martian Moons eXploration (MMX) mission to Mars’ moons Phobos and Deimos passed its mission confirmation review on May 26, completing a critical milestone that now moves the instrument into its final design phase.
Back to the Red Planet Nov 17, 2017
NASA has tapped the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, to build a science instrument for an upcoming Japan-led sample return mission to the two moons of Mars.
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