Mars Exploration Joint Initiative

Mars Exploration Joint Initiative

The Mars Exploration Joint Initiative (MEJI) is an agreement signed between United states' space agency, NASA, and Europe's space agency, ESA to join resources and expertise in order to continue the exploration of the planet Mars.[1] The agreement was signed in Washington D.C. in October 2009.


Discussions between NASA and ESA began in December 2008, driven by the ESA Ministerial Council's recommendation to seek international cooperation to complete the ExoMars mission and to prepare further Mars robotic exploration missions. At the same time, NASA was reassessing its Mars Exploration Program portfolio after the launch of its Mars Science Laboratory was delayed from 2009 to 2011. This provided NASA and ESA with an opportunity to increase cooperation and expand collective capabilities.[2][3] The U.S. and Europe have taken the view that they can achieve more together scientifically at Mars if they combine their expertise. And with both parties' current Mars programmes also experiencing financial pressures, the shared approach means the exploration schedule of a mission every two years can be maintained.[1]

The executive board recommended NASA and ESA establish MEJI, spanning launch opportunities in 2016, 2018 and 2020, with landers and orbiters conducting astrobiological, geological, geophysical and other high-priority investigations, and leading to the return of soil and rock samples from Mars in the 2020's.


The MEJI vision would encompass the following launch opportunities:

  • 2016: A European-led orbiter to study trace gases, including methane in Mars' atmosphere (see: Mars Trace Gas Mission). The mission would also put a static meteorological station on the surface. Europe would handle the entry, descent and landing (EDL) of this station - a capability it has yet to demonstrate.
  • 2018: European and American rovers would be dispatched to Mars. The U.S. would do the entry, descent and landing system (see: ExoMars and Mars Astrobiology Explorer-Cacher).
  • 2020: Under consideration is a network of very small landers focused on geophysics and the environment.
  • NASA will provide Atlas V launch rockets in 2016 and 2018.
  • The ultimate aim is a mission to return Mars rock and soils to Earth, the Mars sample return mission, some time in the 2020's.

As plans develop, they will be reviewed by ESA member states for approval and by the U.S. National Academy of Sciences.[2]


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