Geoscientist’s Toolkit: New Horizons

Artist’s rendering of the New Horizons probe. Image credit: NASA.

This week, NASA’s New Horizons spacecraft flew past Pluto.

Pluto, full-disk in true color, as seen by the New Horizons probe, July 14, 2015.  Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
Pluto, full-disk in true color, as seen by the New Horizons probe, July 14, 2015. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Exploring other worlds up close, and which are different from our own, can be very informative. We may have theories about the composition of worlds like Pluto, of how it formed, how it behaves, and what its surface is like. However, it is not until we go there that we can truly test those hypotheses. In many cases, when we are dealing with worlds vastly different from our own, what we find is surprising, mysterious, and awe-inspiring.

For instance, most pre-New Horizons models would have made Pluto out to be a fairly heavily cratered object, not unlike the Moon. However, that was not at all what was found. The first high-resolution picture released during the flyby, part of a mosaic which is still being put together, had no craters visible. None.

High-resolution image of Pluto's surface, near Tombaugh Regio, taken from 77,000 km above the surface.  Notice the lack of craters in this image.  Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
High-resolution image of Pluto’s surface, near Tombaugh Regio, taken from 77,000 km above the surface. Notice the lack of craters in this image. Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

Given that the history of Pluto is likely to have included significant bombardment by smaller objects, this result makes us rethink our model of the processes happening on Pluto’s surface. From what we know of the frequency of impacts, these surfaces would need to have been recently (geologically speaking, so in the last ~100 Ma) formed, eroded, or otherwise modified.

It is encounters like this which help us understand and consider our models, and to recognize which properties of large rocky bodies are important under which circumstances. What is reshaping Pluto’s surface? How did the various terrains form? Do they happen elsewhere? Where does the energy for these processes come from?

Exploring other worlds keeps our thinking fresh, challenges our assumptions, and inspires us to create new models and experiments to better understand our solar system and our own Earth.

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