WASHINGTON — NASA will spread $15 million in study money among five mission concepts in the first downselect of the agency’s 13th small-class Discovery planetary science competition.

The five concepts include two Venus-bound missions and three missions involving asteroids. Each mission will received $3 million for a one-year study that will help NASA decide by September 2016 which mission, or missions, will move on to the development phase, the agency wrote in a Sept. 30 press release.

“We are not committing to selecting two, but we are stating that we may choose either one or two,” David Schurr, NASA’s deputy director for Planetary Science, wrote in an Oct. 1 email.

Development costs for these Discovery missions would be capped at $500 million, excluding launch and post-launch operations, NASA said. The press release did not identify a launch date for the chosen mission, but NASA officials including Planetary Science Director Jim Green have said in recent months that the winner would launch in 2021.

The five first-round winners are:

The Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI). DAVINCI would study the chemical composition of Venus’ atmosphere during a 63-minute descent and look for active volcanoes on the Venusian surface, NASA said. Lori Glaze of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is the principal investigator. Goddard would manage the project.

The Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy mission (VERITAS). VERITAS would produce global, high-resolution topography and imaging of Venus’ surface and produce the first maps of deformation and global surface composition, NASA said. Suzanne Smrekar of NASA’s Jet Propulsion Laboratory in Pasadena, California is the principal investigator. JPL would manage the project.

Psyche, which would explore the origin of planetary cores by studying the metallic asteroid Psyche. This asteroid is likely the survivor of a violent hit-and-run with another object that stripped off the outer, rocky layers of a protoplanet, NASA said. Linda Elkins-Tanton of Arizona State University in Tempe, Arizona, is the principal investigator. JPL would manage the project.

Frequent Discovery competitor, the Near Earth Object Camera (NEOCam). NEOCam would search for near-Earth objects and, according to principal investigator Amy Mainzer at JPL, could discover 10 times more near-Earth objects than all NEOs discovered to date. NEOCam could also help determine what these objects are made of, NASA said. JPL would manage the project.

Lucy, which would perform the first reconnaissance of the Jupiter Trojan asteroids, objects thought to hold clues to deciphering the history of the solar system, NASA said. Harold Levison of the Southwest Research Institute in Boulder, Colorado, is the principal investigator. Goddard would manage the project.

NASA received 27 Discovery proposals in all, according to the agency’s press release. More than half of these proposed exploring small bodies such as asteroids, comets, Kuiper Belt objects beyond Pluto, and the moons of Mars.

Dan Leone is a SpaceNews staff writer, covering NASA, NOAA and a growing number of entrepreneurial space companies. He earned a bachelor’s degree in public communications from the American University in Washington.