To Pluto and Beyond: Animating New Horizons’ Flight Through the Pluto System

Posted on by .

Stuart Robbins

An exhilarating, pioneering journey came to fruition on July 14, 2015, as NASA’s New Horizons spacecraft made its successful flight through the Pluto system, recording 60 gigabits of data that it is beginning to send to Earth. I’m Stuart Robbins, a research scientist at the Southwest Research Institute in Boulder, Colorado. While I only came onto the project relatively late – in 2012 – I’ve been able to interface with many different groups and people on New Horizons because my primary role was in planning.

The New Horizons mission is one of opportunity, not just in exploring a world in a region to which we’ve never been, but also for people who have a variety of backgrounds, interests and skills. One of my hobbies has been exploring computer-generated images and animations, and I volunteered to create the fly-through animation on this page.

The Pluto system as NASA’s New Horizons spacecraft saw it in July 2015. This animation, made with real images taken by New Horizons, begins with Pluto flying in for its close-up on July 14; we then pass behind Pluto and see the atmosphere glow in sunlight before the sun passes behind Charon. The movie ends with New Horizons’ departure, looking back on each body as thin crescents.Credit: NASA/JHUAPL/SwRI, Stuart Robbins

I strive for realism, so my first step was to build an accurate Pluto system within a 3-D environment. I used the latest data on Pluto’s orbit, its obliquity (how its pole is tilted relative to its orbit), and the orbits of all the known moons to create the system in software. I then “attached” a camera to the latest trajectory information so it would be as if you had a seat on New Horizons, watching Pluto as you zoomed past. I also worked on the lighting so that even the shadows as the spacecraft passes are at the correct angles, and the crescents during departure are at the correct positions.

In my original version, each frame (1/30th of a second) represented one minute of real time, and the field of view was that of the Long Range Reconnaissance Imager (LORRI), New Horizons’ eagle-eyed, black-and-white camera that gives us our closest views.

Unfortunately, the result was cinematically questionable, at best, because of the very brief time that the spacecraft gets its best images and the extreme change in distance between the spacecraft and planetary system over the course of July. I needed an alternative.

The final result was made differently: First, the timescale had to be variable. The final product goes from one second of movie time equaling 30 hours at the beginning and end, to one second of movie time equaling 30 minutes for the closest-approach section.

Second, the field of view could not remain as LORRI if the trajectory were to be realistic. I varied the field of view so that you can see the whole system at the beginning and end, and you can still see Pluto almost as a whole disk during the closest approach.

Third, the camera’s target – what’s in the center of the field of view – had to also vary. The movie starts and ends with the camera targeting the barycenter, the mutual point around which Pluto, Charon and the other four moons orbit. As the movie appears to zoom in for the Pluto flyby, the focus shifts to Pluto itself, and then it moves off Pluto so that it does not appear as though you are about to crash into the surface nor fly through the planet. The camera target remains on Pluto for the solar occultation – when the sun passes behind it – and then moves back to the barycenter for the solar occultation by Charon.

Fourth, the small moons – Styx, Nix, Kerberos and Hydra – were simply too small and faint to be seen to-scale. So I enlarged them by a factor of 5 and brightened them so you can at least see the two larger ones (Nix and Hydra), and I drew in their orbital paths.

Beyond that, everything about the movie is accurate: The Pluto hemisphere we see on closest approach, the lighting and shadows, the atmosphere’s size (though its brightness has been increased), the orbits of the satellites, the colors are our best estimate for what your eye would see, and so on. In addition, this movie retains Celestial North as “up” so that there are no twists, turns nor odd reorientation during the flyby.

The final result is the system as New Horizons saw it at the beginning of July 2015, flying to Pluto for its close-up on July 14, complete with the best maps we have to-date. It’s an incredible look at system we are unlikely to revisit in our lifetimes – though we have the potential to visit other bodies farther still from the sun with the craft as it continues to reveal new horizons in our solar system.