The Boulder-born New Horizons mission now has its next target beyond Pluto clearly in its crosshairs.
NASA is reporting that a long-distance camera on the spacecraft which achieved the historic flyby of Pluto on July 14, 2015 has recorded its first images of the Kuiper Belt object known originally to astronomers as 2014 MU69, but since given the less unwieldy name of Ultima Thule. That moniker is defined by the Planetary Mechanics Blog as meaning, “Beyond the Known World.”
Alan Stern, vice president of the Space Division of Boulder’s Southwest Research Institute and principal investigator on the New Horizon Mission, posted the news on his Facebook page with the brief comment, “Tally Ho, Ultima Thule!”
The images recorded by New Horizons’ Long Range Reconnaissance Imager, or LORRI, revealed a small dim object, still more than 100 million miles away, according to NASA, against a dense curtain of stars. It was recorded Aug. 16, then sent home via NASA’s Deep Space Network. The resulting 48 images represent the mission team’s first attempt to find Ultima with the spacecraft’s cameras.
Originally, that effort was not going to be made until mid-September.
“Our team worked hard to determine if Ultima was detected by LORRI at such a great distance, and the result is a clear yes,” Stern said in a statement. “We now have Ultima in our sights from much farther out than once thought possible. We are on Ultima’s doorstep, and an amazing exploration awaits.”
In an interview Thursday, Stern explained why scientists sought to get a peek at their target ahead of schedule.
“Initially, our calculations indicated that we would not be able to detect Ultima until September, but we made additional calculations that showed maybe it could be detected in August. And since an earlier detection is to our advantage, we decided to try it. And we succeeded,” Stern said.
“If we had found we were off course a little, knowing earlier would have saved fuel, in terms of correcting. We found we were on course, and so this is the best possible outcome.”
No hazards — so far
The Ultima Thule images are the most distant from the sun ever recorded, NASA reported, breaking the record previously set by Voyager 1’s “Pale Blue Dot” image of Earth taken in 1990. New Horizons, which launched Jan. 19, 2006, also set the record for the most distant image from Earth ever recorded, in December 2017.
The Kuiper Belt is a region of the solar system beyond Neptune’s orbit believed to contain countless comets, asteroids and other small bodies composed mainly of ice and rock. Ultima Thule is about 4 billion miles from Earth, and about 1 billion miles farther from Earth than Pluto.
“Ultima is believed to be a building block of small planets like Pluto, and by studying its composition and geology and evolution over time, we hope to understand how the most prevalent class of planets in the solar system, the dwarf planets, were formed,” Stern said.
Scientists see the first detection of Ultima as noteworthy because over the next four months they will be better able to refine New Horizons’ course toward its closest approach at 10:33 p.m. MST on Dec. 31. Mission members believe Ultima is right where they had predicted. Data gleaned from the Hubble Space Telescope shows they had a good understanding of its orbit.
Faculty and students recruited from the University of Colorado by Southwest Research Institute were dispatched in the summer of 2017 to destinations in South Africa and Argentina to study a brief series of occultations, or the passage of Ultima in front of background stars, to see what that might reveal about its size and shape, and whether there are hazards in its proximity.
“It was both successful and productive, and we had another stellar occultation campaign to look for hazards this summer from the country of Senegal, and that was also successful,” Stern said. “So far we have found no hazards.”
If hazards are detected later this fall as the spacecraft draws closer, Stern said its closest approach point can be adjusted outward to avoid them.
A ‘rubber ducky’?
Fran Bagenal, a research scientist at CU’s Laboratory for Atmospheric Space Physics, was a partner to Stern in pushing for the Pluto mission as early as 1989.
“It’s cool,” she said on seeing the new images. “It means we’re getting there. We’re still a long way off. But it means we’ve got a target and it’s just going to get bigger and bigger and bigger in the next few months.”
She added, however, “bear in mind, this is a very small object,” estimated to be no more than 20 miles wide.
“And we don’t know if it is round, or is it peanut shaped or is it a rubber ducky (shape)” like Comet 67P, probed by the European Space Agency’s Rosetta spacecraft.
Stern said New Horizons is on course to pass about 3,500 kilometers, or roughly 2,000 miles, over the surface of Ultima, “which is about three times closer than we went to Pluto. We expect to get much better and much more detail.”
The Ultima flyby will be the first-ever close-up exploration of a small Kuiper Belt object and the farthest exploration of any planetary body in history, shattering the record New Horizons itself set at Pluto in July 2015 by about 1 billion miles.
It’s not yet known whether Ultima is what’s known as a contact-binary, meaning a system whose two components are so close that they touch, an orbiting binary, or even if it has small moons.
Before too long, Stern said, “We’ll find out.”
Charlie Brennan: 303-473-1327, brennanc@dailycamera.com or twitter.com/chasbrennan