|Names||Mars Explorations with Landers and Orbiters (2008)|
Mars Exploration of Life and Organism Search (2015)
|Mission type||Technology demonstrator|
|Mission duration||Nominal: 68 sols |
Desired extension: 1 Mars year
|Landing mass||EDM (sky crane): 909 kg (2,004 lb)|
Rover: 150 kg (330 lb)
|Payload mass||15 kg (33 lb)|
|Power||Solar panels (1.5 m²)|
Battery: 720 Wh
|Start of mission|
|Launch date||2022 (proposed)|
|Landing site||Valles Marineris or Marte Vallis|
|Distance driven||Goal: 50 km (31 mi)|
MELOS (Mars Exploration of Life and Organism Search) 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.
Japan's aerospace agency (JAXA) started to develop the mission concept on 2008, when MELOS stood for "Mars Explorations with Landers and Orbiters" or "Mars Exploration with Lander-Orbiter Synergy" which included several landers to be deployed simultaneously, that were to study meteorology and atmospheric gas escape. 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:
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".
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.
The scientific objectives of the mission include: 
See also: Mars 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 (5 km) during the entry and landing event. Its flight duration is estimated at 4 minutes, covering a distance of 25 km (16 mi). Its only scientific payload would be a camera.
The proposed landing sites will target 'wet' environments and include Valles Marineris (Melas Chasm and Juvantae Chasm), located near the confirmed recurring slope lineae, and Marte Vallis near dark slope streaks. 
Since the mission aims for access to a "special region", strict planetary protection sterilization protocols must be followed to prevent forward contamination of Earth microbes to Mars.