Checking out the Kuiper Belt
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.