1 billion miles past Pluto, we might learn how planets form


On Jan. 1, 2019, NASA will set a record by reaching the most distant object ever visited by a robotic spacecraft. The New Horizons spacecraft will fly by dwarf planet 2014MU69 (MU69 for short), which lies 5 billion miles from Earth. 

That’s a billion miles farther than Pluto, which New Horizons visited in 2015.


MU69 is unlike any other world that our technological surrogates have visited. But we do know that objects like MU69 were the building blocks of the planets when they formed 4.5 billion years ago, so it could hold key clues to kinds of materials from which Earth formed. The carbon in our bodies, and even the water we drink, came from objects like these when they were incorporated into the forming Earth.

MU69 is also unique among all the planets and smaller objects NASA spacecraft have visited. It is primordial. That is, it has not changed since it formed. A visit to MU69, then, is a visit to the earliest moments in the life of our solar system.

To illustrate how far MU69 is from Earth, consider the speed of light. It takes light from our moon about 1.5 seconds to reach Earth. It takes light about 8 minutes to reach us from the sun. But at the distance of MU69, it takes over 6 hours for light (and radio signals) to reach us! 

The New Horizons spacecraft astonished us all with its discoveries at Pluto. We saw a world with diverse geology, a richly complex atmosphere, and an intriguingly unique climate system. We saw vast dark plains rich in carbon, and slowly boiling nitrogen ice glaciers heated by an unknown energy source below. We also found intriguing hints of a subsurface ocean. 

So what can we expect to find on MU 69? We really don’t know. It is small, about 20 to 30 miles in diameter, and dark, much like graphite. MU69 is known as a Kuiper Belt Object (KBO).  More than 2,000 KBOs have been discovered, and extrapolation suggests there are more than 100,000 such objects in these distant regions.  


In every epoch of human exploration, our exploration steps get larger. When humans left the African savanna, they likely made treks of only a few miles. When the ships left Spain to explore the unknown western regions, they sailed several thousand miles before encountering the Americas. When the Apollo astronauts went to the moon, the one-way trek was a quarter of a million miles. When we sent the Viking spacecraft to Mars, our exploration steps increased to more than 100 million miles. Since New Horizons passed Pluto, it has expanded our “backyard in space” by one billion miles.

In the future, these steps may seem primitive and tiny, but they will be a record showing the descendants of our humanity’s drive to explore and discover. That’s an important legacy.

With the New Horizons visit to MU69, we can share a great sense of accomplishment with the rest of humanity. In spite of all of the national and international conflicts, in spite of all of the natural and human-caused disasters, and in spite of the continual and varied challenges to our national and personal dignities, we can occasionally work together to accomplish something so amazing that it borders on the magical. 

The New Horizons spacecraft has taken us to the most distant worlds in our solar system, and shortly it will take us to the earliest moments of our solar system’s life. Previously it took us to Jupiter, where it flew down the magnetic “tail” of its enormous planetary magnet. Then to Pluto, where we discovered how surprisingly beautiful an ice world could be. And now it is taking us to a totally new type of world that we have not visited before, and we don’t know what we will find. 

MU69 has been nicknamed Ultima Thule, a term used in medieval times to signify a place beyond the known lands. Ultima Thule is indeed a very appropriate nickname — but only for a short time longer. 

Michael ESummers is a professor of planetary science and astronomy at George Mason University in Fairfax, Virginia, and member of the NASA/New Horizons science team.