Landing on Pluto might just be a hop, skip and a jump away

There are a lot of crazy mission ideas in the space exploration community. Some are simply better funded than others. One of the first avenues for funding crazy ideas is NASA’s Advanced Concepts Institute. In 2017 and again in 2021, it funded a mission study of what most space enthusiasts would consider only a modestly ambitious goal, but what those outside the community might consider outlandish — landing on Pluto.

Two main questions arise in the mission design: How would a probe be slowed down arriving at Pluto, and what kind of lander would be useful on Pluto itself? The answer to the first is one that is becoming increasingly common on planetary exploration missions: aerobraking.

Pluto has an atmosphere, albeit a thin one, as confirmed by the New Horizons mission that whizzed by in 2015. One of the advantages of the small planet’s relatively weak gravity is that its low-density atmosphere is nearly eight times that of Earth, providing much greater goal. for a fast-arriving airbrake craft to target.

Much of the NIAC Phase I project was focused on the details of this aerobraking system, called the Enveloping Aerodynamic Decelerator (EAD). Combined with the lander, this system forms the “entry ship” around which the mission is designed. Apparently, it could alternatively include an orbiter, and there are plenty of other missions discussing how to put an orbiter around Pluto. Therefore, the main focus of this paper is to focus on the lander.

After aerodynamic braking and deceleration to a few tens of meters per second, from 14 km/s during the interplanetary cruise phase, the mission would drop its lander payload, then rest on the surface to rise again under its own power. The answer to the second question, what kind of lander would be useful on Pluto is – a hopper.

Hoppers have become increasingly popular as a tool for exploration everywhere from the moon to asteroids. Some obvious advantages would include visiting a wide variety of interesting scientific sites and not having to navigate complex ground obstacles. Ingenuity, the helicopter that accompanied the Perseverance paved the way for the idea, but in other words, the atmosphere is not thick enough to carry the helicopter. So why not use the current favorite method of almost all spacecraft – rockets?

The hopper would fire its on-board thrusters to reach an area on Pluto’s surface and then land elsewhere. Then he could do some science in his new place before taking off and doing it again somewhere else.

The NIAC Phase I Final Report describes the mission’s five main science objectives, including understanding surface geomorphology and performing some in-situ chemical analyses. The hopper design would enable these goals much better than a traditional rover at a relatively low weight because Pluto’s gravity is so weak.

Other goals of the report include mathematical calculations of the trajectory, including the aerobraking itself and the stresses and strains of the materials used in the system. The authors, who work primarily for the Global Aerospace Corporation and ILC Dover, two private companies, also updated Pluto’s atmospheric models with new New Horizons data, which they then fed into the airbrake model they used. Phase I also included the design of the lander/hopper, integration of all science and navigation components, and estimation of their weight.

The mission’s original launch window was planned for 2029 back in 2018, although now, despite receiving a NIAC Phase II grant in 2021, that launch window seems wildly optimistic.

Since the mission would require a gravitational assist from Jupiter, the next potential launch window would be in 2042, with the lander finally reaching Pluto’s surface in the 2050s. This later launch window is likely the only feasible one for the mission, so we may have to wait nearly 30 years to see if it comes to fruition.