Solar System: Things to Know This Week
Time for a little reconnaissance.
Our New Horizons spacecraft won't arrive at its next destination in the distant Kuiper Belt—an object known as 2014 MU69—until New Year's Day 2019, but researchers are already starting to study its environment thanks to a few rare observational opportunities this summer, including one on July 17. This week, we're sharing 10 things to know about this exciting mission to a vast region of ancient mini-worlds billions of miles away.
1. First, Some Background
New Horizons launched on Jan. 19, 2006. It swung past Jupiter for a gravity boost and scientific studies in February 2007, and conducted a six-month reconnaissance flyby study of Pluto and its moons in summer 2015. The mission culminated with the closest approach to Pluto on July 14, 2015. Now, as part of an extended mission, the New Horizons spacecraft is heading farther into the Kuiper Belt.
2. A Kuiper Belt refresher
The Kuiper Belt is a region full of objects presumed to be remnants from the formation of our solar system some 4.6 billion years ago. It includes dwarf planets such as Pluto and is populated with hundreds of thousands of icy bodies larger than 62 miles (100 km) across and an estimated trillion or more comets. The first Kuiper Belt object was discovered in 1992.
When New Horizons flies by MU69 in 2019, it will be the most distant object ever explored by a spacecraft. This ancient Kuiper Belt object is not well understood because it is faint, small, and very far away, located approximately 4.1 billion miles (6.6 billion km) from Earth.
To study this distant object from Earth, the New Horizons team have used data from the Hubble Space Telescope and the European Space Agency's Gaia satellite to calculate where MU69 would cast a shadow on Earth's surface as it passes in front of a star, an event known as an occultation.
5. An International Effort
One occultation occurred on June 3, 2017. More than 50 mission team members and collaborators set up telescopes across South Africa and Argentina, aiming to catch a two-second glimpse of the object's shadow as it raced across the Earth. Joining in on the occultation observations were NASA's Hubble Space Telescope and Gaia, a space observatory of the European Space Agency (ESA).
6. Piecing Together the Puzzle
Combined, the pre-positioned mobile telescopes captured more than 100,000 images of the occultation star that can be used to assess the Kuiper Belt object's environment. While MU69 itself eluded direct detection, the June 3 data provided valuable and surprising insights. "These data show that MU69 might not be as dark or as large as some expected," said occultation team leader Marc Buie, a New Horizons science team member from Southwest Research Institute in Boulder, Colorado.
7. One Major Missing Piece
Clear detection of MU69 remains elusive. "These [June 3 occultation] results are telling us something really interesting," said New Horizons Principal Investigator Alan Stern, of the Southwest Research Institute. "The fact that we accomplished the occultation observations from every planned observing site but didn't detect the object itself likely means that either MU69 is highly reflective and smaller than some expected, or it may be a binary or even a swarm of smaller bodies left from the time when the planets in our solar system formed."
On July 10, the SOFIA team positioned its aircraft in the center of the shadow, pointing its powerful 100-inch (2.5-meter) telescope at MU69 when the object passed in front of the background star. The mission team will now analyze that data over the next few weeks, looking in particular for rings or debris around MU69 that might present problems for New Horizons when the spacecraft flies by in 2019. "This was the most challenging occultation observation because MU69 is so small and so distant," said Kimberly Ennico Smith, SOFIA project scientist.
On July 17, the Hubble Space Telescope will check for debris around MU69 while team members set up another "fence line" of small mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina.
New Horizons has had quite the journey. Check out some of these mission videos for a quick tour of its major accomplishments and what's next for this impressive spacecraft.
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