Approximately 35 planetary scientists are exploring a follow-up mission to Pluto or to other as yet unexplored dwarf planets in the Kuiper Belt.
The scientists met in Houston on April 24 in a workshop setting the early stages for either a Pluto orbiter and lander or several flyby missions to Kuiper Belt Objects as far away as Eris.
New Horizons’ findings at Pluto surprised scientists by revealing a geologically active world with a variety of terrains, layered hazes, and a possible subsurface ocean.
The findings raised a host of new questions such as how Pluto stays so geologically active; what created Sputnik Planitia, the smooth, craterless left side of Pluto’s heart feature, and whether an underground ocean is present.
Because the mission was a flyby, the spacecraft’s instruments were able to map only 48 percent of Pluto and its large moon Charon in high resolution, principal investigator Alan Stern noted.
In contrast, a Cassini-like orbiter could spend several years exploring the Pluto system, using gravity assists from Charon to visit the four small moons, much like Cassini used Titan’s gravity to maneuver through the Saturn system.
A Pluto orbiter would have to launch on a large rocket, such as the Space Launch System (SLS) NASA is currently developing. The spacecraft would have to carry a large fuel tank so it could speed to Pluto, then brake to enter orbit.
Stern envisions a follow-up mission using a propulsion system like the one used by NASA’s Dawn probe to Vesta and Ceres.
Getting to Pluto would take approximately five or six years while slowing down to enter orbit would extend the journey to anywhere between seven and nine years.
After several years of exploring Pluto and its moons, the orbiter could use Charon’s gravity to escape the Pluto system and journey to other Kuiper Belt planets.
Instead of going back to Pluto, some scientists in the group prefer three or four first flyby missions to other Kuiper Belt dwarf planets, which have been found to be surprisingly heterogeneous and diverse.
Using a heavy launch vehicle and an electric propulsion system, a spacecraft could even travel to Eris, which is close to 100 AU (astronomical units, with one AU equal to the average Earth-Sun distance or 93 million miles) from the Sun.
In order for a mission to be prioritized, scientists need to get it into NASA’s Planetary Science Decadal Survey, which determines exploration priorities for the next ten years.
The next Decadal Survey will be held from 2020 through 2022, with the results to be published in 2023.
If approved and funded, the mission would launch in approximately twelve years.