The New Horizons spacecraft sent back the first images that begin to reveal Ultima's shape. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
NASA's New Horizons spacecraft is on track to make space exploration history just 33 minutes into 2019 Eastern time, scientists said Monday. That's when it's expected to pass just 2,200 miles away from a tiny object known as Ultima Thule, located about 4 billion miles from Earth in a region of space known as the Kuiper Belt.
Why it matters: The flyby may give scientists new and vital insights into how the solar system and planets like Earth first formed. This is the first time scientists have ever closely studied a Kuiper Belt object, and scientists said Monday the flyby is proceeding according to plan but without a guarantee of success.
- “We are straining at the capabilities of this spacecraft, and by tomorrow we’ll know how well we did,” said Alan Stern, New Horizons' principal investigator, at a press conference.
What to watch: Scientists will have to wait until New Year's Day to learn whether their efforts were successful, as the spacecraft is on autopilot, using commands sent hours ago due to the distance.
Researchers say they know a very limited amount about Ultima Thule, whose nickname means "beyond the known world." That lack of advance knowledge makes it a particularly tantalizing target.
“We hardly know anything about it,” said Stern. “That’s all going to change, and it’s going to change this week.”
The backstory: Scientists believe Ultima Thule has been frozen in time since the solar system first formed about 4.6 billion years ago.
- The Kuiper Belt, where Ultima Thule is located, is a region of icy bodies beyond the orbit of Neptune that are thought to be leftovers from the solar system's early days.
- There are thought to be hundreds of thousands of objects like Ultima Thule in the Kuiper Belt, and the spacecraft will attempt to gather data on others to learn more about them, and how Ultima Thule might differ from them.
"It's a very special region that we're very excited to explore," said John Spencer, a deputy project scientist with the Southwest Research Institute.
The details: The flyby is requiring scientists to stretch the capabilities of the New Horizons spacecraft, which gathered unprecedented data on Pluto in 2015 after launching in 2006. Ultima Thule, for example, is about 80 times smaller than Pluto.
- New Horizons is traveling at about 32,000 miles per hour.
- It has been programmed to pass just 2,200 miles away from Ultima Thule, taking pictures and gathering data with its 7 different instruments on board.
"We only get one shot at it. Nothing like it has ever been done before."— Alan Stern, Principal Investigator with New Horizons
We're likely to see the first photo on New Year's Day. More images and data from the spacecraft will flow back to Earth during the course of the week and beyond, given the roughly six hours required to transmit data one way at 1,000 bits per second across 4 billion miles, Stern said.
The knowns: Scientists know the general size of Ultima Thule, which is on the order of about 15 to 20 miles in diameter, and would be able to fit between Washington, D.C. and Baltimore. They also think it's reddish in color.
The unknowns: Researchers are particularly interested in finding out more about the object's geological makeup, how it compares with other Kuiper Belt objects, whether it's releasing any gases and if it has small satellites nearby.
How to watch: To follow along with the mission, watch a livestream from Johns Hopkins University's Applied Physics Laboratory in Maryland, and monitor its social media accounts. Events will also stream online via NASA.
Editor's note: This piece has been corrected to show that the flyby distance between New Horizons and Ultima Thule will be close to 2,200 miles (not 22,000 miles).