WASHINGTON ­— NASA could select two of the five finalists for the latest of its Discovery-class planetary missions next year for full-scale development, but doing so would mean skipping a planned solicitation for another Discovery round in 2017, NASA’s top planetary science official said here Oct. 5.

NASA’s Discovery class of small, principal investigator-led planetary science missions, which dates back to 1992, has seen its launch cadence slow in the last decade. The agency once thought it could launch a mission every two years, but budget constraints have reduced that frequency to roughly one every three years.

On Sept. 30, NASA picked five Discovery finalists — including two Venus concepts and three asteroid concepts — to evenly split $15 million worth of one-year study grants. The principal investigators for each mission use the money to mature their mission concepts and development plans, and generally polish up their missions for the final NASA review.

“If we end up selecting two, then we wouldn’t put out a call for the next Discovery as we originally had planned, which is in 2017,” Jim Green, NASA director of planetary science, said here during a meeting of the NASA Advisory Council’s planetary science subcommittee.

It will be about a year before NASA has to cross that bridge. The final cut for the latest Discovery competition, NASA’s 13th, will not be until September 2016, Green said.

Of the five finalists, four plan to use technology NASA offered up as government-furnished equipment to any principal investigators willing to accept the risk of using the unproven payloads on their missions, according to slides Green presented here.

Three finalists agreed to use an experimental NASA Deep Space Optical Communications payload: a laser-based communications package that can send more data back to Earth more quickly than traditional radio-frequency communications systems.

Volunteers for the optical communication system were:

  • The Near Earth Object Camera, a previously proposed mission to catalog asteroids, comets and other bodies that will pass close by Earth.
  • VERITAS, the Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy mission, an orbiter that would make high-resolution maps of the Venusian surface.
  • Psyche, a probe seeking to explore a metallic asteroid.

A proposed mission dubbed Lucy to explore so-called Trojan asteroids near Jupiter, meanwhile, would use NASA-furnished Advanced Solar Arrays. Lucy is alone among the finalists in that it would explore objects in the outer solar system.

The one finalist to forgo the use of government-furnished equipment is the Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission, which would descend into the Venusian atmosphere to study its interaction with the planet’s surface. The mission would also scan the Venusian surface for active volcanoes.

The latest Discovery mission is cost-capped at $450 million, excluding the price of a launch.

New Frontiers, New Technology

Meanwhile, NASA’s next competition for a New Frontiers medium-sized planetary mission — these are principal investigator-led missions with a larger budget than those in Discovery — will start sometime in the next year, Green said.

Green would commit only to getting the next New Frontiers announcement of opportunity out the door by the end of the government’s 2016 fiscal year, which began Oct. 1 and ends Sept. 30, 2016.

Osiris Rex at Asteroid Bennu
Osiris Rex asteroid sample-return probe. Credit: NASA/Goddard/Chris Meaney

The New Frontiers program dates back to 2002. NASA has more or less stuck to the five-year launch cadence it originally had in mind for the program. The third New Frontiers mission, the Osiris-Rex asteroid sample-return probe, is set to launch in 2016. The second, the Juno Jupiter probe, launched in 2011. The fourth in the line is notionally set to launch in 2021.

Competition for a fifth New Frontiers mission would then begin “before the end of 2023,” Green said.

NASA is trying to pave the way for hopefuls in the fourth competition by evenly splitting some $8 million in so-called New Frontiers Homesteader grants among eight different risk-reduction efforts. The hope, Green said, is that by tackling technology challenges early, the next New Frontiers competition will be easier to judge.

According to Green’s slides, winning Homesteader proposals, along with the principal investigators, are:

  •  Sample Acquisition, Containment, and Thermal Control Technology for Comet Surface Sample Return, led by principal investigator Steven Squyres at Cornell University in Ithaca, New York.
  • Venus Entry Probe Prototype, led by Lori Glaze of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
  • An Advanced Pointing Imaging Camera, led by Ryan Park of NASA’s Jet Propulsion Laboratory in Pasadena, California.
  • Navigation Doppler Lidar Sensor for Reliable and Precise Vector Velocity and Altitude Measurements, an entry, descent and landing technology study led by Farzin Amzajerdian of NASA’s Langley Research Center in Hampton, Virginia.
  • A “small, low-cost hopping lander for asteroid exploration” called POGO, led by Elena Adams at the Johns Hopkins University’s Applied Physics Laboratory in Laurel, Maryland.
  • The Atmospheric Constituent Explorer System for Planetary Probe Missions led by Stojan Madzunkov at the Jet Propulsion Laboratory.
  • Active-Tracking Microelectromechanical System Micro-Concentrator for Low Intensity, Low Temperature Missions — roughly translated, improvements to existing spacecraft power systems — led by Scott Singer of SpectroLabs in Sylmar, California.
  • Tunable Laser Spectrometer Risk Reduction for Saturn Probe and Venus In-Situ Explorer New Frontiers Missions, led by Chris Webster at the Jet Propulsion Laboratory.

Some, but not all, of these Homesteader technologies could be used for multiple high-priority missions identified for the fourth New Frontiers competition in the 2011 planetary science decadal survey, which set science priorities for NASA’s robotic exploration program through 2022.

Those high-priority missions include: Comet Sample Return; Lunar South-Pole Aitken Basin Sample Return; Trojan Tour and Rendezvous; Venus In-Situ Explorer; and Saturn Probe.

The fifth New Frontiers competition would allow proposals for all the missions not selected in the fourth competition, plus a Lunar Geophysical Network and a probe to explore Jupiter’s volcanic moon Io.

The next New Frontiers mission is capped at $850 million, excluding launch, according to slides Green presented here.

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.