HISTORY WRITTEN FOR CBS NEWS AND USED WITH PERMISSION
Three years and a billion miles from Pluto, the NASA's New Horizons probe is on the verge of at least one more innovative, unique milestone: the New Year flyby of a small body known as 2014 MU69, unofficially called the Ultima Thule — beyond the known world. – in NASA's naming contest.
Like Pluto, Ultima Thule (pronounced LLP-Li) is the inhabitant of the remote Kuiper Belt, a vast kingdom beyond the orbit of Neptune inhabited by countless dwarf planets and a reservoir of frozen remnants left from the birth of the Solar System, 4.6 billion years ago.
Ultima Thule, a little more than the dim point of light, even for the Hubble Space Telescope, will be the most distant object ever investigated directly, and this record is likely to stand for decades, if not longer.
If everything goes well, New Horizons will race with its goal at a speed of 32,000 miles per hour – almost nine miles per second – at 12:33 am on New Year's Day, passing within about 2,200 miles from the still invisible surface of Ultima Thule.
After four hours, the spacecraft will send its dish antenna to Earth to confirm a successful collision. After a few hours, the first high-priority images and other data will begin to return to the inner solar system.
“People in the whole team are ready, they are in the game, we cannot wait to explore them,” said Alan Stern, the principal researcher at New Horizons, on Friday. “Three and a half years have passed (since Pluto was circled), we have worked so hard, people are ready to see this return and see what we can learn about the birth of our solar system.”
At a distance of 4.1 billion miles from Ultima Thule Earth, radio signals would take 186,000 miles per second, six hours seven minutes and 58 seconds to cross the abyss, waiting for scientists at the Johns Hopkins University Laboratory of Applied Physics near Baltimore. It is expected that the first high-resolution image will be presented during the January 2 briefing.
Despite the ongoing closure of the government, it is expected that the public will be able to follow NASA's satellite television channel. But just in case, the Applied Physics Laboratory, which created and operates the New Horizons for NASA, plans to post images and other data on the New Horizons web page and on the lab's YouTube channel.
Only a few images and other high-priority data are expected to expect New Horizons to move beyond the Sun when viewed from Earth on January 4, which will temporarily break the link. But even when the descending channel resumes, it will take about 20 months to bring the entire treasury to Earth.
This is due to the huge distances, the weak signal from the 30-watt New Horizons transmitter, and other NASA antenna requirements covering the globe that are used to communicate with spacecraft through the solar system.
For scientists eager to study the intact remains of the original cloud of stony debris formed in the solar system, a long wait is worth it.
“Everything that we visited earlier warmed up at some point,” Stern said in an interview earlier this month. “Asteroids are in orbit near the Sun, comets … were born cold, but we only visited comets when they are in Earth orbit, when they are warm. Heat, heat causes chemical reactions, it can control surface processes, etc., which create evolution. ”
Ultima Thule, in his words, "is not recognized by any of these things at all." It is classified as a “cool classic,” that is, a Kuiper belt body with an almost circular orbit that is only slightly tilted to the plane of the Sun. planets system. Another large population of Kuiper belt bodies, consisting of material that originated closer to the Sun, was supplanted by gravitational interactions in the distant past.
But not a cool classic, but Ultima Thule.
“He was born four billion miles from the Sun, he was always there, his temperature just above absolute zero,” said Stern. “I do not believe that there is any object that we have ever visited, which has been so cold throughout its existence. So it’s really a time capsule, it’s a scientific value. ”
According to Stern, “New Horizons” will fly more than two times closer to Ultima Thule than during the passage of Pluto, “so the images will be much more detailed”.
"We are going to find out how this thing is built, how it is developed, what it is made of, if it has an atmosphere, if it has satellites, if it has rings, we are going to measure its temperature, we We are going to measure its radar reflective ability, we will find out if it is surrounded by a dust cloud left over from the seam, ”he said.
“All this and more, because we are not going to just shoot,” he added. “We map its surface, we display it in color, and in addition to this, we map it in stereo, so we have topography everywhere. We will not only determine its composition, but also compare it from place to place to see if it is the same everywhere or it consists of smaller building blocks. ”
The meeting has five main objectives: to characterize the geology, morphology and topology of Ultima Thule; map its surface color and composition; determine its structure; search for satellites and rings; and look for any kind of coma or atmosphere.
“Ultima Thule can be heavily cratered, seedless or even smooth from ancient streams and ancient activities,” said Cary Lisse, a fellow at the New Horizons research group. "We do not know. We just won’t find out until we get to January. I'm waiting to be surprised.
Launched almost 13 years ago in January 2006, New Horizons flew past Jupiter in February 2007, using a giant planet as a target for testing their instruments and, more importantly, using gravity to transfer the ship to an accelerated trajectory to Pluto.
Despite this, moving 100 times faster than a jet airliner during his voyage, it took him another eight long years to reach his goal in July 2015, flying at a distance of 7,800 miles to collect first close-up photos and lots of data. about the most famous dwarf planet of the solar system.
While the collision with Pluto was the main objective of the spacecraft, the mission leaders knew that it would leave rocket fuel and that its nuclear power supply would ensure the operation of the probe during the 2020s. Long before Pluto’s flight, the team requested the observation time on the Hubble Space Telescope to find possible targets beyond Pluto, which may be close enough to the New Horizons trajectory to include another span.
Hubble discovered Ultima Thule on images taken on June 26, 2014. It was cataloged as MU69 of 2014 and received the minor planet number 485968. Analysis of its orbit showed that the New Horizons can reach it using the trajectory correction maneuver after Pluto.
After completing the collision with Pluto, the leaders of NASA approved the extension of the mission. A carefully planned missile firing was carried out, adjusting the rate of New Horizons, to organize the upcoming meeting with Ultima Thule.
New Horizons did not find his quarry until August 15 of this year, at a distance of more than 100 million miles. It was a barely visible point of light, and it will remain a slightly brighter point of light until Monday, the day before the flight.
However, scientists have at least some idea of what to expect when New Horizons arrive. Based on observations of the occlusion, in which Ultima Tule passed in front of a background star, viewed from Earth, the researchers believe that the target is an elongated body, which is about 17 miles wide. It may consist of two bodies in a close orbit or two petals that are physically related, the so-called “contact binary”.
Researchers know that Ultima Thule receives only about 0.05 percent of Earth’s sunlight, and they know that it is reddish. But they still do not know his exact size, whether he has any rings, moons or any traces of the atmosphere.
“In fact, we have no idea what to expect,” said Stern during the conference in October. “We only discovered it in 2014, when the Hubble Space Telescope was working at the limit of its fantastic capabilities. We could find out enough about its orbit to intercept it and aim at it. But little else we know.
Whatever they find out, it will happen very, very quickly. The small size of the Ultima Thule means that New Horizons cameras will not be able to resolve it until the day before the collision.
For example, on Sunday, the best photos will have a resolution of about 6.2 miles per image element or pixel, and Ultima Thule will be between two and three pixels. On New Year's Eve, the resolution will improve to 3.4 miles per pixel, and the body will be between five and six pixels.
But by the evening of the New Year, the resolution will increase to 1000 feet per pixel, and the next day – 500 feet per pixel, and Ultima Thule will stretch to 215 pixels.
“Although we are moving at about the same speed as Ultima, from which we drove through Pluto, Pluto is about the size of a continent like North America,” said Stern. “And so, when we were 10 weeks from Pluto, we could already make out its disk in much the same way as the Hubble Space Telescope, and every week we could see more and more details.
“But Ultima 10 weeks is just a point in the distance. And it will remain a point at a distance, until just a day before the flight we begin to allow it. The day after the flight, we will have high-resolution images, we hope that the resolution will be even higher than that of the best images of Pluto. So it will be fast.
New Horizons is equipped with six main instruments: an imaging spectrometer, known as Alice, a multispectral camera in visible light called Ralph, a LORRI long-range reconnaissance scanner that includes an 8-inch telescope, a solar wind particle detector, an energetic particle spectrometer and a dust meter built by a student.
In addition, his radio system includes a scheme that allows for accurate analysis of changes caused by the passage of signals from the Earth through the atmosphere.
The data is stored on backup eight-gigabyte solid-state recorders and sent back to Earth using a transmitter in the X-band, using a 83-inch-wide fixed dish antenna. The data transfer speed will be slightly better than 1000 bits per second.
Stern said that meeting the New Horizons is a much more difficult task than Pluto.
“This one is more difficult for a number of different reasons. Firstly, it is smaller, it is weaker, and therefore it is harder to track, more difficult to get comfortable, ”he said. “It's 100 times smaller, 10,000 times weaker. Secondly, every year an integrated nuclear power source produces less energy. So now we need to much more carefully control what tools and avionics are included, we need to manage our power much more carefully. ”
Thirteen years after launch, the only radioisotope thermoelectric generator of a spacecraft, or RTG, produces only about 190 W, which is enough to power three standard light bulbs.
In addition, since the science team does not know what to expect, New Horizons will carefully search for the area around Ultima Thule, looking for moons or other objects, therefore “there will be many images of empty sky just because we are trying to cover the whole territory in case we discover the moon late. "
Four days after the flight, communications with the New Horizons will be suspended as the spacecraft moves behind the Sun, as viewed from Earth. The research team has set data playback priorities so that the high-resolution image of Ultima Thule reaches Earth before the power outage begins.
“This is much faster than anything we did on the New Horizons,” said Stern. “In essence, this is a night-time transformation from a point at a distance into the real world. And I think that the first week of January, when we return the first detailed images, will be exciting! Not only from a scientific point of view. I think that for people who follow the news, it’s amazing to just see and think about what our race can do, what our species can do. ”
When asked if New Horizons could achieve the third Kuiper Belt goal in the future, Stern said that he wanted his team to focus on Ultima Thule in the near future. But after the meeting is over, “we will look for another target for the flyby. I can not promise anyone, you or NASA, that we will find one (but), I can tell you the following: my team wants nothing but to get the second. ”
Editor's Note. A part of this story was originally written for Astronomy Now magazine and is used here with permission.