NASA Missions of Opportunity give the U.S. scientific community the chance to participate in non-NASA missions by providing funding for a science instrument or hardware components of an instrument. They also offer the possibility to use an existing NASA spacecraft for a new science investigation.  Five Discovery Program Missions of Opportunity have been selected.
   
ASPERA-3
(Analyzer of Space Plasma and Energetic Atoms), an instrument flying on the Mars Express spacecraft, is studying the interaction between the solar wind and the Martian atmosphere.                                   Read More
M3
The Moon Mineralogy Mapper, or M3, flew aboard India's first deep space mission, Chandrayaan-1, and will characterize and map the mineral composition of the Moon at high resolution.
   
EPOXI
EPOXI is an extension of the Deep Impact mission that searched for planets around other stars and observe a new comet.
Stardust-NExT
The Stardust New Exploration of Tempel 1, or NExT, mission used the Stardust spacecraft to revisit comet Tempel 1, the target of the Deep Impact mission.
   
Strofio
Strofio will use a unique mass spectrometer to study the atoms and molecules that compose Mercury's atmosphere to reveal the composition of the planet's surface.