The Solstice of the Year of Pluto

A year ago, in my Winter Solstice entry, I jubilantly noted that 2014, the year referred to by fans of Pluto and New Horizons as “Pluto Eve,” was giving way to the “Year of Pluto.” Anticipating the “something wonderful” mission Principal Investigator Alan Stern predicted we would find on the small, distant planet, I noted, “The light is about to shine on a very dark and mysterious world.”

As Tim Dean, editor of “The Conversation” website pointed out in his 2015 review of science and technology—which placed Pluto first—2015 seems to have come and gone nearly as fast as New Horizons flew by Pluto.

This is the year Pluto was a star, a celebrity that made the cover of multiple magazines and was recognized by many news outlets and websites as a top science story.

Like many who have followed this mission, I already miss the building buzz and excitement that characterized the final six months of New Horizons’ approach to Pluto.

Does the Year of Pluto end with 2015, I’ve questioned over the last several weeks.

Our view of this small planet has been transformed from a tiny dot, at best a pixelated Hubble image, to an actual world, with jagged mountains, valleys, snakeskin terrain, flowing ices, a layered haze, and one particular feature that has generated awe and wonder worldwide—the prominent heart-shaped region known as Tombaugh Regio, named in honor of Pluto discoverer Clyde Tombaugh.

Everything about this tiny world that is more geologically active than Mars has surprised scientists, who continue to brainstorm in an effort to explain its complex surfaces and processes.

Only about 25 percent of the data New Horizons’ seven instruments took on flyby day has been returned. The rest is still on the spacecraft, and the downlink will not be complete for approximately another 300 days.

The fact that 75 percent of the data is still to come makes a compelling case for the position that the Year of Pluto will go on past the calendar year 2015.

Even when all the data is back, its study and analysis will take years, as can be seen from the fact that 25 years after Voyager 2 flew by Neptune, a scientist studying those images identified an undetected moon orbiting the ice giant.

And because the data is generating so many more questions, particularly regarding Pluto appearing to have an internal heat source, it seems inevitable scientists will want to go back for another view.

Stern often describes the sequence of planetary exploration as starting with a flyby, then moving to an orbiter, a lander, a rover, and finally, a manned expedition.

So far, the only planetary body that has undergone all these levels of exploration is the Moon. Mars has been explored with several rovers, and plans are underway to send astronauts there sometime during the 2030s.

The development of new technologies could reduce a spacecraft’s travel time to Pluto. Small cube satellites could be sent in a follow up mission. Significantly, the US has just now resumed manufacturing the type of plutonium required for a mission so far from the Sun.

Pluto remains a prime destination because it is one of several solar system worlds that has or might have a subsurface ocean that could host microbial life. That puts it in a category that includes Ceres, Jupiter’s moon Europa, Saturn’s moons Titan and Enceladus, and possibly other, similar worlds at the forefront of the search for extra-terrestrial life.

We will never again see Pluto the same way we did just a year ago. When in 2006, four percent of the IAU voted to “reclassify” Pluto, they effectively made a decision for a world about which they knew nothing. How can anyone classify a world without knowing what it is, what it is made of, and what processes are taking place on it?

Recently, French scientist Jon Luc Margot published a mathematical formula which he claims astronomers can use to determine whether an individual exoplanet “clears its orbit” and therefore should or should not be classed as a planet by the IAU.

Incredibly, Margot actually stated on record that it doesn’t matter what an object is made of because its composition has no bearing on whether or not it is a planet. The only thing that counts, in his view, is whether the object clears its orbit.

Most people who look at the complex world imaged by New Horizons see a planet. Far from being fundamentally different from those sometimes referred to as “the big eight,” Pluto actually has much in common with them. Ironically, Pluto shares some surface characteristics with Earth and Mars. It is not a rubble pile loosely held together or a “giant comet” composed largely of ice.

2015 ends with the debate over Pluto’s status and the question of how to define a planet remaining unresolved. It might remain unresolved for a long time. Meanwhile, every new image and detail sent back across four billion miles serves to confirm that this strange world is not just a Kuiper Belt Object but half of a binary planet system.

For thousands of years, the Winter Solstice on Earth has been a time of rebirth and renewal, the beginning of the transition from darkness to light.

We’ve only begun that transformation from darkness to enlightenment when it comes to Pluto. Regarding the adventure of unraveling Pluto’s secrets, the only appropriate language is, “To be continued…”