NASA probe sets sights on Pluto and beyond

News Science

On July 14, NASA’s New Horizons probe made its closest approach to Pluto, marking the culmination of years of research, planning, and space flight.  Like sailor’s tales of newly discovered lands, the crisp images of Pluto’s surface have captured our imaginations.

Illustration by Nora Wu
Illustration by Nora Wu

The New Horizons probe began its journey on Jan. 19, 2006, and then swung around Jupiter to accelerate to an incredible 14 kilometers per second on Feb. 28, 2007.

As the fly by of Pluto neared, scientists such as UVic’s Jon Willis from the Department of Physics and Astronomy became increasingly excited about what was in store. They expected to see a surface pockmarked with craters from billions of years of comet and asteroid impacts. They expected a geologically dead ball of ice and rock.  What they saw instead is astounding.

For its age, Pluto has very few surface craters. According to Willis, this means that the surface has been essentially ‘repaved,’ but how? Pluto is too small to have geology like Earth’s and too far from the Sun to have its surface melt. It turns out that since it’s so cold on Pluto, water behaves like rock (a crygeological phenomenon), creating mountains and volcanoes of water ice.

This phenomenon still requires some heat to melt the ice mantle somewhat, so where does this heat come from?  It may be residual heat left from Pluto’s creation, which would be contrary to current theories about heat loss, or it could be from radioactive decay of elements in the core.

One feature of Pluto that has received a lot of attention is the “heart.” This is a heart-shaped, lightly coloured plain made of various types of ice.  It has 3 400 metre peaks of water ice (as opposed to methane ice), as well as nitrogen glaciers along its edge.

So what’s next for the New Horizons probe? Its rockets have enough fuel to redirect it to one of three potential targets in the Kuiper Belt, a huge cloud of water ice, rock chunks, and other objects close to Pluto’s size. These rock and ice chunks have likely been around since the birth of our solar system, and if any of these were active, it would be an even bigger shock than the new Pluto discoveries.

The New Horizons probe has a connection to Victoria as well: the government lab NRC Herzberg is home to two scientists who have contributed to this flyby. Stephen Gwyn, a UVic PhD graduate, produced star maps used by the New Horizons team to find the probe’s position in space by comparing the map with images from the probe. Another scientist, JJ Kavelaars, is using a telescope to look at potential targets in the Kuiper Belt for the probe’s next flyby.

Data from the flyby will filter back to Earth over the coming months.  Considering the discoveries made
from just a few pictures, the complete data set will surely capture our imaginations again.