WASHINGTON — NASA might end up funding two of the five mission concepts just selected for further study in the latest Discovery-class planetary science mission competition, a senior agency official said.

“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.

NASA winnowed a field of 27 competitors down to five Sept. 30, evenly splitting $15 million in one-year study money among two Venus concepts and three asteroid concepts in the long-awaited first down-select for the agency’s 13th small robotic solar-system mission competition. Final selection, of either one mission or two, is expected in September 2016, NASA said in a press release.

The agency said nothing about launch dates in its latest Discovery announcement, but officials including Jim Green, the agency’s planetary science director, have said the Discovery 13 launch will be in 2021 — five years after the 12th Discovery mission, the Mars lander InSight, is scheduled to launch.

Development costs for the next Discovery mission, or missions, would be capped at $500 million, excluding launch and post-launch operations, NASA said. A single principal investigator proposes and leads each Discovery mission.

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.

The first Discovery mission, Mars Pathfinder, launched in 1997. Intended to promote rapid development of missions relatively riskier than NASA’s science flagships, the series has seen its launch cadence slow over the last 10 years, even as NASA’s appetite for risk within the program has decreased.

InSight is a case in point. The solar-powered mission to Mars beat out two nuclear-powered missions to the outer planets. Solar power is cheaper than nuclear power. It also takes far less time to for a spacecraft to reach Mars than the outer solar system.

Moreover, InSight, unlike the missions it beat, was based heavily on hardware NASA has already flown successfully. InSight is not scheduled to launch until March ­— five years after the 11th Discovery mission, the Gravity Recovery and Interior Laboratory.

Excepting the long wait for InSight, there has been a two-year gap between Discovery launches since 2005 when Deep Impact, the 8th in the series, lifted off from Cape Canaveral Air Force Station in Florida.

Discovery missions have not launched within roughly a year of each other since Deep Impact followed the Messenger Mercury probe to space. Messenger ended its mission in April, when it was intentionally crashed into Mercury’s surface.

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.