NASA Scientist for a Day - Kaipūtaiao NASA mō te Rā

Hello it's me Triton. I was the moon you flew by on your final mission with Voyager 2 in 1989. I strongly believe you should send another spacecraft because I have lots to show you and if you don’t in approximately 3.5 billion years the pull of Neptune will split me up and I will become a ring system.

The first reason your visit would excite me is because I would like to show you more about my reflective surface. My craters are surrounded by volcanic planes. Icy lava flows over my rough surface creating ice shows by forcing nitrogen and methane into the atmosphere. This nitrogen then condenses to form nitrogen snow as it drifts back down.

I am unique because I have a retrograde orbit and I orbit the opposite way from Neptune.. When you had Voyager fly by, my South Pole was facing the sun and I was part way through the season of spring. Hard to believe I’m so far from the sun and yet the sun's heat can cause these seasons.

I would also like to show you how my frost is formed from frozen nitrogen and methane. I’m a cold moon, with a temperature of -235 degrees Celsius, so the gases freeze. You might even see my nitrogen ice clouds. This is all part of my thin atmosphere. In fact I’m 70,000 times less dense that your Earth!

If you return you should try to find my interior ocean. This has been formed by the ice in my core melting due to the heat from Neptune taking some of my energy. The traces of ammonia may be linked to why my ocean doesn't freeze.

You may think I am lonely but you are probably wrong. I have a young surface and I know you know this because you have noticed I only have a few craters. Also my nitrogen gas plumes are probably caused by the ocean so all these clues maybe mean life could exist here.

I see from your trident mission video that you may aim to visit me in 2038 with a launch date of 2025. If you want to compare new data with what you saw on your first visit, this time slot is very important due to my long seasons. You need to bring a plasma spectrometer that helps sample particles on my surface and in my plumes. You will be able to fly a lot lower, you can therefore get a better understanding of magnetic fields. You should include a radio science instrument as this would help you figure out if I do have an ocean and how deep it actually is and if there is any life. On your flight you only got about 40% of my surface so don't forget a variety of cameras because you need to capture images from a distance and up close as well as my other side facing Neptune.

I really hope I see you in 2038!

Being the largest moon of Neptune, Triton has attracted the interest of humans, from professional scientists to astronomy enthusiasts since it was discovered by the British astronomer William Lassell in 1846.

Triton is a main astrobiological target in the search for alien life. It was identified as the prime candidate in the Roadmaps to Ocean Worlds study in 2019. Trident was proposed to the NASA Discovery Programme in 2019, whose proposal includes a thorough analysis of Triton and why a mission to Triton would be important.

The possible existence of a sub-surface ocean is the most compelling feature of Triton, which would if confirmed, drag the habitable zone to approximately 29AU. While conditions necessary for an internal ocean prevails, it remains for a future mission to prove the existence of one.

Crater counts suggest that Triton’s surface is the second youngest planetary body in the solar system, with less than 10Ma of age. Images of Triton’s southern sub-Neptune hemisphere were taken by Voyager 2, on its journey to the Kuiper Belt in 1989. By applying photogeology to these images, scientists have concluded that Triton has an endogenic interior with a network of tectonic structures, several cryovolcanic landforms, extensive cantaloupe terrain and several particulate plumes and associated deposits. This establishes Triton as a geologically active planetary body.

Scientists suggest that Triton has enough heat to maintain an internal ocean. Heat sources include,

• Radiogenic heat
• Heat preserved from being captured to Neptune’s orbit – Triton is confirmed as a captured Kuiper Belt Object
• High axial tilt
• Tidal activity

Triton’s atmosphere consists mainly of nitrogen, in addition to carbon monoxide and methane. A polar cap, probably containing nitrogen, was observed. The presence of methane facilitates the production of organic materials, especially if it comes into contact with liquid water, which supports life.

While Triton’s atmosphere is exceptionally thin, scientists suggest that it is sufficient to be a major sink for volatile substances and dynamic enough to support movement.

Equipment to be included in a mission should strive to detect internal oceans and their properties, observe changes, map the surface, to detect liquid particles in Triton’s plumes and to detect energy outputs to its atmosphere. Wide and narrow angled cameras, magnetometers, infrared spectrometers and a radar system would be some examples for equipment able to perform those functions. Trident suggests using a plasma spectrometer to investigate the ionosphere and radio science, while Roadmaps to Ocean Worlds mentions UV spectroscopic imaging to study Triton’s plumes.

The main objective of a mission to Triton would be to confirm the existence of a sub-surface ocean that could host life. Trident identifies explanations on Triton’s young geological age and intense ionosphere as factors to be explored while investigating the geyser plumes of Triton would also be beneficial. Finding answers to these questions as well as extra information would lead to more specific and accurate hypotheses on one of the most sought-after suspicions of mankind: Does alien life exist in our solar system?