WASHINGTON — Over half of the 28 proposals NASA received for a $450 million robotic solar-system mission launching in 2021 seek to explore small bodies such as comets, asteroids or tiny moons.

The reveal came after a marathon session of presentations here June 30 at the latest NASA-chartered Small Bodies Assessment Group (SBAG) meeting, where representatives of 16 proposed missions for NASA’s 13th Discovery competition briefed attendees for nearly three hours.

Discovery missions are proposed and led by a single principal investigator. Mission costs excluding launch are capped at $450 million, with NASA bearing all expenses. The agency will pick at least two finalists around September to square off in a second round of competition that will last about a year, Jim Green, NASA’s director of planetary science, said July 14. Finalists will receive up to $3 million of study-money to further their case. NASA will pick winner around September 2016, Green said.

While not all of the presenters at the June SBAG meeting disclosed industry sponsors, several did. Among the big-name companies who have thrown their hats into the ring as potential spacecraft primes in the ongoing Discovery competition are:

  • Ball Aerospace & Technologies Corp., Boulder, Colorado, picked as prime by five presenters.
  • Boeing Defense, Space and Security, St. Louis, selected by one presenter.
  • Lockheed Martin Space Systems of Denver, identified as a prime on three of the proposals briefed at SBAG.
  • Orbital ATK, Dulles, Virginia, named as a prime by two presenters.

Here are all 16 proposed Discovery missions presented to the SBAG June 30, including name, principal investigator, proposed operations, and, when divulged, the would-be prime contractor. Proposals are sorted alphabetically by destination type.


  • Lucy. Principal investigator: Hal Levison, a planetary scientist at the Southwest Research Institute in Boulder, Colorado. The mission is a flyby tour of five so-called Trojan asteroids close to Jupiter’s orbit. Prime contractor: Lockheed Martin.
  • NEOCam. Principal investigator: Amy Mainzer. Mainzer, based at NASA’s Jet Propulsion Laboratory in Pasadena, California, is also principal investigator of the NEOWISE mission, which repurposed the Wide-field Infrared Survey Explorer to observe near-Earth asteroids and comets. NEOCam would essentially do the same thing with a new spacecraft carrying instruments that do not need cryogenic cooling (the Wide-field Infrared Survey Explorer’s primary astrophysics mission was cut short when its cooling system failed). Prime Contractor: Ball.
  • Advanced Jovian Asteroid Explorer. Principal investigator: John Mustard, Brown University in Providence, Rhode Island. The ambitious proposal would cram flybys, orbits and landings into a single mission, taking a 12-year cruise out to a Trojan asteroid close to Jupiter’s orbit and, after a year of observations, dropping a small instrument package on the asteroid.
  • Dark Asteroid Rendezvous. Principal investigator: Keith Noll, a planetary astronomer at the Goddard Space Flight Center in Greenbelt, Maryland. The mission would orbit and map two asteroids in the inner solar system expected by scientists to carry volatile materials that originated in the outer solar system. Prime Contractor: Orbital ATK.
  • Binary Asteroid In-Situ Explorer. Principal investigator: Dan Scheeres, University of Colorado, Boulder. The mission would orbit a near-Earth asteroid and drop explosive pods onto its surface to create new craters. Ejecta from these craters would help the probe better understand the body’s surface composition than remote observation alone. Prime Contractor: Ball.
  • Psyche. Principal investigator: Lindy Elkins-Tanton, Arizona State University. The mission would orbit a metallic asteroid that, in its origin, may have been a planetary core dislodged by a violent impact with some other solar-system body.


  • Comet Radar Explorer. Principal investigator: Erik Asphaug, Arizona State University. The mission would attempt to map the nucleus of comet Temple 2. Prime Contractor: Orbital ATK.
  • Comet Hartley Analysis to Gather Ancient Links to Life. Principal investigator: Jessica Sunshine, University of Maryland. The mission, a reboot of the Comet Hopper lander that made the finals in the prevous Discovery competition, would visit and observe comet Hartley 2. Unlike Comet Hopper, the new mission will visit only a single comet. Prime Contractor: Lockheed Martin.
  • Primitive Material Explorer. Principal investigator: Hunter Waite, the Southwest Research Institute in San Antonio, Texas. This mission would also visit and observe comet Hartley 2. Prime Contractor: Ball.

Kuiper belt and beyond:

  • Kuiper. Principal investigator: Jim Bell, Arizona State University. The space telescope would fly to the gravitationally stable Earth-moon Lagrange Point 2 and observe the faraway Kuiper belt beyond Pluto’s orbit. Prime Contractor: Ball.
  • Whipple. Principal investigator: Charles Alcock, Harvard-Smithsonian Center for Astrophysics. Another space telescope to observe both the Kuiper belt and the Oort cloud, which lies beyond. The cloud is home to many comets that occasionally make million-year journeys to the inner solar system only to melt as they get too close to the sun. Prime Contractor: Ball.

Mars Moons:

  • Mars Moon Exploration, Reconnaissance, and Landed Investigation.  Principal investigator: Scott Murchie, principal professional staffer at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. The combination probe-lander would remotely observe and touch down on both martian moons, Phobos and Deimos.
  • Phobos and Deimos Origin Assessment. Principal investigator: Carol Raymond, manager of the Small Bodies Program at NASA’s Jet Propulsion Laboratory in Pasadena, California, and deputy principal investigator of the onoging Dawn mission, which is now exploring the planetoid Ceres. Raymond’s proposal involves exploring Mars’ two moons with an orbiter built on one of Boeing’s all-electric 702SP satellites. Once the primary mission is finished, Raymond would turn the spacecraft over to NASA’s Mars program for use as a communications relay. Prime Contractor: Boeing Defense, Space and Security.
  • Phobos and Deimos and Mars Environment. Principal investigator: Anthony Colaprete, NASA’s Ames Research Center, Mountain View, California, and principal investigator of the Lunar Crater Observation and Sensing Satellite that launched in 2009. Colaprete’s mission would feature an upgraded version the Lunar Atmosphere and Dust Environment Explorer spacecraft, launched to Earth’s moon in 2013. Prime: NASA Ames

Multiple types of small bodies:

  • Proteus. Principal investigator: Karen Meech,the University of Hawaii’s Institute for Astronomy. The probe would visit both a comet and an asteroid to investigate whether Earth’s water might have been planted here by extraterrestrial bodies. Prime Contractor: Lockheed Martin.
  • Main Belt Asteroid and NEO Tour With Imaging and Spectroscopy. Principal investigator: Andy Rivkin, the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. The probe would visit nine asteroids, including near-Earth asteroids and some in the so-called main asteroid belt, which lies between the orbits of Mars and Jupiter.

Openness among competitors has become a hallmark of the latest NASA Discovery competition. Until a downselect, NASA is not required to identify any of the proposals it received, or say who submitted them. Even then, the agency typically divulges only the names of the proposals it selects for further study.

However, principal investigators may share details of their missions, if they wish. This time around, they have done so, early and often.

The most recent SBAG meeting is not the only time this year aspiring Discovery principal investigators have shared their plans. Some Discovery candidates, including missions to Mars and Venus, went public in Berlin during the German Aerospace Center’s Low Cost Planetary Mission Conference in June. Other hopefuls came out even earlier, during the Universities Space Research Association’s Lunar and Planetary Science Conference in March at The Woodlands, Texas.

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.