NASA has announced the selection of four mission concept studies for its Discovery program. The selections focus on compelling science and exploration questions that are not addressed by current missions and include a return to Earth’s neighbor Venus, a probe of Jupiter’s volcanic moon Io, and a flyby of Neptune’s moon Triton. The mission concepts were chosen based on their potential science value and feasibility, but they are not yet official missions. Each mission concept will receive $3 million for a nine-month detailed study to mature the technology and concepts, after which each mission team will submit a Concept Study Report. NASA will then evaluate the reports and choose two missions to develop towards flight.

The selected proposals are:

DAVINCI+ (Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging Plus), which will study the atmosphere of Venus using a descent probe and map the surface rock types from orbit. The principal investigator is James Garvin of NASA’s Goddard Space Flight Center, which is also providing project management.

VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy), which will map Venus’ surface using radar and infrared emissions. The principal investigator is Suzanne Smrekar of NASA’s Jet Propulsion Laboratory, which is also providing project management.

Io Volcano Observer (IVO), which will use a series of close flybys of Io to assess how magma is generated and erupted. Alfred McEwen of the University of Arizona is the principal investigator with the Johns Hopkins Applied Physics Laboratory providing project management.

Trident, which will use a flyby of Neptune’s moon Triton to map its surface and characterize the active surface processes of this potential ocean world. Louise Prockter of the Lunar and Planetary Institute/Universities Space Research Association is the principal investigator, with NASA’s Jet Propulsion Laboratory providing project management.