triton hopper
NASA's proposed mission to Neptune’s largest moon
NASA proposes a mission to Neptune's largest moon
While NASA’s Europa Clipper mission gathers momentum for its upcoming adventure to Jupiter’s icy moon in 2023, NASA is also preparing for another moon mission – one that will take humankind to Neptune’s moon Triton.
Triton is the largest moon of Neptune and the seventh largest moon in the Solar System, but it is a bit of an oddball. Triton was first visited – and still, only – by NASA’s Voyager 2 probe in 1989, and scientists found it to be very peculiar. For starters, it orbits in the opposite direction to the rotation of Neptune. Its surface looks young, with a lack of impact craters, and even exhibits geysers and winds, suggesting it is a geologically active body. These indicate that Triton is not a moon, but likely a world captured from the Kuiper Belt. Triton could actually be a mislabelled Kuiper Belt Object (KBO) captured by the gravity of our Solar System’s furthest known planet. Triton is larger than the dwarf planet Pluto, and is visually similar to the dwarf world. This makes Triton an attractive target as it provides an opportunity to study a relatively nearby potential KBO that is also geologically active.
To successfully send the probe to Triton, astronomers want to utilise an eclectic combination of solar-electric propulsion and an aerocapture system, which would reduce the Hopper's velocity to allow it to enter an elliptical orbit around the celestial body. This journey would take roughly 12 years from Earth. This provides a quicker trip time compared to other options and these technologies are continuing to improve as time goes on.
The aim of the mission is to land the Triton Hopper in the southern hemisphere of Triton which will eventually travel towards the equator over a two-year period, hopping once every 24 days. Although the project is only in its preliminary stages – having entered phase two in March 2018 which will continue to iron out the details on paper – the ideas being suggested are brilliantly creative and very efficient.
The gravity on Triton is roughly only eight per cent of Earth's gravity; this would mean that not as much propellant is needed to hop across the surface to examine the different terrain and atmosphere. The Hopper would use a radioisotope heat source to keep the probe from freezing in the dark, cold depths of the Solar System, but the space probe will also look to use this heat to mine and melt frozen nitrogen from the surface. This frozen nitrogen could replenish the fuel tank and means astronomers and engineers don’t have to rely purely on the fuel they send with the mission. This will hopefully power jumps that reach a kilometre (0.6 miles) high and five kilometres (three miles) long, transporting the roughly-450 kilogram (992 pound) space probe across the surface.
“Triton is the largest moon of Neptune and the seventh largest moon in the Solar System, but it is a bit of an oddball”