NASA | JPL-Caltech | Trident | 2020 Jun 16
One of four concepts being considered for a Discovery Program mission, Trident would investigate one of the solar system's most unusual worlds.
When NASA's Voyager 2 spacecraft flew by Neptune's strange moon Triton three decades ago, it wrote a planetary science cliffhanger.
Voyager 2 is the only spacecraft ever to have flown past Neptune, and it left a lot of unanswered questions. The views were as stunning as they were puzzling, revealing massive, dark plumes of icy material spraying out from Triton's surface. But how? Images showed that the icy landscape was young and had been resurfaced over and over with fresh material. But what material, and from where?
How could an ancient moon six times farther from the Sun than Jupiter still be active? Is there something in its interior that is still warm enough to drive this activity?
A new mission competing for selection under NASA's Discovery Program aims to untangle these mysteries. Called Trident, like the three-pronged spear carried by the ancient Roman sea god Neptune, the team is one of four that is developing concept studies for new missions. Up to two will be selected by summer 2021 to become a full-fledged mission and will launch later in the decade.
Investigating how Triton has changed over time would give scientists a better understanding of how solar system bodies evolve and work.
The oddities of Triton could fill an almanac: As Neptune rotates, Triton orbits in the opposite direction. No other large moon in the solar system does that. And Triton's orbit lies at an extreme tilt, offset from Neptune's equator by 23 degrees. About three-quarters the diameter of our own Moon, Triton isn't where it used to be, either. It likely migrated from the Kuiper Belt, a region beyond Neptune of icy bodies left over from the early solar system. ...
