Those of us who study the ways that planets form and evolve often feel like we are investigating a crime scene. It’s not that planet formation is a crime! It’s simply that when we look at a planet now we are looking at the end product of four and a half billion years of changes, sometimes catastrophic, that modify the formation materials and sometimes mask the formation processes. So we must study planets very carefully, using as many clues as we can obtain, in order to reconstruct their history.
The kinds of clues that we work with are typically a planet’s composition, its motions, and its atmosphere. The questions we try to answer are how it formed, how it grew to its present size, and why it has the composition that it has. We want to know why some planets like the Earth are habitable, whereas others like, for example Venus, are not.
But is a very difficult task! Four and a half billion years is a very long time. That length of time is about four hundred and fifty thousand times the length of the history of human civilization. Much has happened during that time which has changed the planets. Sorting out how a planet formed as opposed to what happened to it afterward is often possible, but it takes very careful deduction. How much easier it would be if we had a time machine to go back in time to see what things were like so long ago!
But we do have a time machine — of sorts. There are in fact a few pieces of the original stuff — left over debris — from which planets formed that are still in orbit around our sun. In the inner solar system these are the asteroids that tell us about the kinds of materials that came together to form planets like the Earth. NASA has visited several of these with spacecraft, and what we have learned has helped us write textbooks on how the Earth formed. But we have yet to have a spacecraft visit one of the original pieces from which the giant planets, like Jupiter, formed.
This is about to change on Jan. 1, 2019, and change perhaps in a very dramatic way. The NASA/New Horizons spacecraft that performed a flyby of Pluto in July 2015 is now about one billion miles beyond Pluto, and it is approaching a new type of planetary debris — designated as 2014MU69 and nicknamed Ultima Thule. Ultima Thule is known as a Kuiper Belt Object (KBO) — one of over one hundred thousand small planetoids that orbit in a vast torus just beyond Pluto’s orbit. These objects are believed to be the remnants of giant planet formation.
The flyby of Ultima Thule will hopefully give us clues to understanding the history of the outer solar system. But we’ve never studied a KBO up close before. When the New Horizons spacecraft visited Pluto we found a world of diverse and complex geology, including slowly moving and bubbling glaciers. We found a world with dynamic winds and atmospheric chemistry that was producing organic compounds. We even found a hint that Pluto may have an internal ocean of liquid water! All of these things were completely unexpected — even to “world experts” on Pluto!
Will Ultima Thule be like Pluto? We don’t believe so because Pluto is a planet that was formed by the accumulation of objects like Ultima Thule, but we don’t know for sure. The New Horizons flyby will give us our first close look at this new type of “building block” for planets, and we simply don’t know what we will find. But if experience is any guide, “first looks” at objects in space are always astonishing. We anticipate being very surprised at Ultima Thule as well!
This type of science is normally called discovery science — it is pushing the frontier of knowledge simply to know more about our place in the universe. But there is a long-term practical aspect to understanding our solar system that is rarely considered — yet perhaps vital to the survival of the human race.
At Pluto we found a world of ice, rocks and metals, and organic materials that formed deep deposits on its surface. We believe that KBOs will also have these in abundance. These are the sorts of raw materials that humanity will need when we move outward to colonize space over the next few hundred years. We will need them, e.g., for making rocket fuel, growing plants, and for building materials for habitats.
The New Horizons flyby of Ultima Thule will give us a time machine view of the history of our solar system — as it was billions of years ago. But this time machine may also give us a glimpse of the “not-to-distant” future as well — where humanity will obtain the raw materials needed for space colonization.
Michael Summers is a professor of planetary science and astronomy at George Mason University.
The views and opinions expressed in this commentary are those of the author and do not reflect the official position of The Daily Caller.
