Category Archives: New Horizons mission

Kuiper Belt, New Horizons mission, Pluto

New Horizons Extends Planetary Exploration

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Musings on Exploration

Pluto north pole region exploration
The north polar region of Pluto, with canyons running vertically across the region, named Lowell Regio. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

We got another green light from the New Horizons mission this week, indicating its journey of exploration of continues. It means the spacecraft is alive and well, although mostly hibernating on its way out to its next target. The spacecraft is speeding along, continuing its headlong outward journey from Earth, exploring “new worlds” out there. If what it saw at Pluto is any indication, planetary scientists will likely have a few surprises in store.

Already, they’re puzzling over the shape of the next target world, 2014 MU69 (first spied by Hubble Space Telescope). Could it be two worlds in close orbit? A bi-lobed world in the deeps of the Kuiper Belt? We’ll all find out much later this year.

Targeting a Distant Planet

Pluto atmosphere exploration
Sunlight filters through and illuminates Pluto’s complex atmospheric haze layers.  Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Pluto has always been a target for exploration, although the launch windows don’t open very often. Heck, it wasn’t even discovered until early in the 20th century. Missions to the nearby planets didn’t begin until the 1960s, and the outer planets in the late 1970s.

Pluto started getting taken seriously as the most distant known planet in the late 1980s. Eventually, the New Horizons project was selected after a few tentative starts and a competition. In September 1989, a group of us students put together a Pluto Perihelion party to celebrate the planet’s closest approach to the Sun.

Over beers and volleyball, we got into a fairly heated discussion about when Pluto’s tenuous atmosphere would freeze out and fall to the surface. And, that was a concern for any mission that would head out that way. Would it get there in time to measure the atmosphere before it “fell down”? To be sure, that “freezing out” wouldn’t take place for many years, and we speculated when that might happen. It was a subject of much debate. We all had to wait until a spacecraft could actually get out there. But, no doubt about it, Pluto was definitely an object of fascination years before we got there with a spacecraft.

The Attempt to Demote a Distant Planet

Pluto also became an object of controversy. In the years since its perihelion, only a few months after New Horizons was launched, nobody expected the IAU to decide Pluto wasn’t a planet. That happened even before it had been explored. Most planetary scientists weren’t sure what to expect from a world so far out that it takes a decade to get there, even for a spacecraft that is the fastest ever sent. So, why pre-judge the world before it’s explored? I still wonder that to this day. Nothing about that “decision” made sense, except perhaps for the proffering of the term “dwarf planet” to cement Pluto’s planetary status.

Moving on to the Next Distant World

MU69 exploration and artist's concept
The Kuiper Belt object 2014 MU69 may be a double-lobed object or possibly a more spherical one with a chunk missing. The New Horizons spacecraft will fly by this object on December 31, 2018. Courtesy JHU/APL/SWRI/Alex Parker

Fast-forward to now, when we get those weekly “green lights” from New Horizons. It’s kind of heartening to know that a tiny outpost of human intellect is speeding out through the solar system, extending our senses to such a cold, dark, and distant region.

New Horizons has done a great deal at Pluto. However, it’s really just getting started in the Kuiper Belt. We’re ready for the next stop on the tour, even as we look back to see that the pesky Plutonian atmosphere still hasn’t fallen down. Even more fascinating, Pluto’s fascinating surface belies activity deep inside the planet.

What will 2014 MU69 tell us? I can’t wait to find out!

Kuiper Belt, New Horizons mission

The Green Light Special from the Kuiper Belt

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Checking out the Kuiper Belt

New Horizons path out through the Kuiper Belt.
New Horizons and its trajectory toward its next Kuiper Belt object of study. Courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. (click to enlarge)

This week’s green light signal from the Kuiper Belt-bound New Horizons came when the spacecraft was more than 436 million kilometers from Earth. It was traveling a speed (with respect to the Sun) of 14.2 meters per second. At the rate it’s going, NH will encounter object MU69 on the first day of January 2019. The Voyager and Pioneer spacecraft are much farther away and have sent back information about the interplanetary medium at their locations. They’re moving in other directions, no longer seeking out new worlds. New Horizons is still an active planetary exploration mission, extending our gaze to the Kuiper Belt. You can follow its progress on the mission website.

Reasons For Kuiper Belt Explorations

As NH and other spacecraft move out through these distant reaches, the question comes up: what do we expect to learn out there? Of course, the obvious answer is that we want to find and study other worlds. It’s not likely that NH will find more distant places. However, it is on track to study at least one more. MU69 is its next target. This tiny worldlet was found by the Hubble Space Telescope and has been studied from Earth through occultation tracking. That means astronomers have watched it via telescopes as it passed between us and a star. Those observations helped them determine a rough shape for MU69.

Of course, there are other worlds in the Kuiper Belt, such as Eris and Quaoar. No spacecraft is headed toward them. New Horizons’s study of Pluto, its moons, and MU69, is likely the best “close-up” look we’re going to get of places in the Kuiper Belt.

It’s not just worlds out there that beckon our interest. The solar wind still has an influence on the distant solar system, and interplanetary space in the region contains a fair amount of dust and gas. Those are important to measure. As well, cosmic rays and other radiation from beyond the solar system can be detected and measured. It’s as important to know all of the components of the outer solar system—from planets and their moons to magnetic fields, solar wind particles, and cosmic rays.