NASA’s New Horizons spacecraft’s trip to Pluto indeed opened up a few discoveries about the dwarf planet. However, principal investigator of the New Horizons mission and some scientists argue that those findings weren’t enough.

According to The Verge, Stern and some scientists from a workshop at Houston had been thinking about going back to Pluto. The reason is that the findings from New Horizons’ mission last 2015 revealed that the dwarf planet is a geologically active world as reported. Theories also suggest that Pluto has a liquid ocean.

Furthermore, Stern stated that there is no specific plan laid out yet. “The news is that the community is forming around the concept of going back to Pluto with an orbiter mission that would stay and study the planet for years, and do it in ways that we could not have in a simple flyby like New Horizons,” he explained.

Regarding Stern’s concept, he mentioned that compared to New Horizon, NASA should send an orbiter to Pluto instead. With that orbiter, he identified that 100 percent of the planet could be identified since New Horizon had just captured one side of the planet and didn’t quite observed the planet as it only passed by in one day.

Stern also added that aside from their planned orbiter to observe Pluto, they aim for a lander as well. In which, would only happen if they have enough budget as Stern mentioned. Meanwhile, Astronomy reported that a 1991 flyby proposal for Neptune along with Pluto was planned before the New Horizon was launched. The mission was due to the collaboration of Alan Stern, Jonathan Lunine, and David Morrison.

The three was mentioned to send space probes to Neptune and Pluto, dubbed as the “Neptune/Pluto Flight Project.” The probes for each planet was to be named Neptune Mariner and Pluto Mariner. Neptune’s Mariner was set to study the blue planet’s magnetic fields.

However, the Neptune/Pluto Flight Project plan was scraped due to its need of radio thermal gradients (RTGs), which are now in short supply at NASA. The power and heat supply’s requirement of Plutonium-238 which can’t be naturally produced was also identified to halt the proposal.