MELOS is a Japanese rover mission concept under study for an engineering demonstration of precision landing, and to look for possible biosignatures on Mars using a rover. JAXA has not published updates since 2015.
History
Japan's aerospace agency started to develop the mission concept on 2008, when MELOS stood for "Mars Explorations with Landers and Orbiters" which included several landers to be deployed simultaneously, that were to study meteorology and atmospheric gasescape. The first MELOS concept would have consisted of an orbiter and up to 4 small landers; all elements would be launched together on the same rocket. The orbiter would study the atmosphere, its and interactions with the solar wind, and image the current weather. Each of the four stationary landers would have been deployed on pre-determined landing sites and perform different measurements:
Orbiter — Meteorology
Lander A — Surface
Lander B — Astrobiology —This lander would analyze soil near a methane vent. The proposed method is to use fluorochromedye and a microscope to stain and scan for proteins and cellular membranes. The target sensitivity would be 10 cells / 1 g of soil. It would also detect other organic biosignatures or biomolecules.
By 2015, MELOS was down-scaled to a rover mission for an engineering demonstration, and possibly an aircraft. Under the latest concept, MELOS stands for "Mars Exploration of Life and Organism Search".
Rover
As of July 2015, the concept proposal includes a robotic rover whose primary objective is an engineering demonstration for long-range roving. Its secondary objective is science, specifically: meteorology, geology and astrobiology. The demonstration rover would use NASA's sky crane system for landing, and once on the surface, would deploy the MELOS rover.
Scientific objectives and payload
The scientific objectives of the mission include: ;Meteorology
Basic meteorological observations, dust devil observation and dust entrainment. Payload: thermometer, anemometer, barometer. Optional instruments include: a spectroscope for methane detection, a dust particle sensor, electromagnetic & sonic wave measurement of dust, and short range LIDAR.
;Geology
Geological description of the landing site including interior layered deposits and subsurface structure of regolith. Payload: ground penetrating radar, multi-band stereo cameras, VIS-NIR spectrometer. Optional: Geochronology Instrument.
;Astrobiology
Identification of biosignatures. Payload: sample arm, fluorescence microscope, and an optional "daughter rover" to access samples in difficult places.
Aircraft
The mission concept also contemplates the optional deployment of a robotic airplane as a flight technology demonstrator. It would have a wing span of 1.2 m, mass of 2.1 kg and would be released at an altitude of 16,400 feet during the entry and landing event. Its flight duration is estimated at 4 minutes, covering a distance of. Its only scientific payload would be a camera.
