قالب وردپرس درنا توس
Home / Science / On the eve of the New Horizons flight, Ultima Thule is still holding on to its secrets – Spaceflight Now

On the eve of the New Horizons flight, Ultima Thule is still holding on to its secrets – Spaceflight Now



This image shows the first detection of 2014 MU69 (nicknamed "Ultima Thule"), with the highest resolution mode (known as "1 × 1") of the Long Range Reconnaissance Imager (LORRI) aboard New Horizons. Probe is used. Three separate images, each with a 0.5 second exposure time, were combined to produce the image shown here. All three pictures were taken on December 24, 2018. Photo credits: NASA / Johns Hopkins University of Applied Physics / Southwest Research Institute

LAUREL, Maryland – One day before NASA's New Horizons probe arrives in a frozen outpost nicknamed Ultima Thule 4.1 billion miles (6.6 billion Kilometers) away from Earth, basic facts about the object in the size of the city on Sunday escaped the scientists. The ground crew was preparing for a flood of data and images that would unmask the unexplored world on the edge of the solar system. 19659003] Ultima Thule – officially known as the 2014 MU69 – is no more than 30 kilometers long and lies a billion miles behind Pluto, the last world New Horizons visited. The color is reddish, and scientists have determined their position with remarkable accuracy for an object just discovered in 2014. Apart from that, Ultima Thule's appearance is associated with the ideas of scientists and space enthusiasts.

This will change quickly as pictures taken by New Horizons black and white and color cameras return to Earth on Tuesday and Wednesday.

"We do not know about MU69," said Alan Stern, New Horizons Principal Investigator, Southwest Research Institute. "We have never achieved a goal in space history that we knew less about, and it is remarkable that we are about to learn a great deal about it.

"Today I can not. I'll tell you more than five facts," Stern said in a meeting with reporters on Sunday. "We know its orbit, we know its color, we know the shape and the reflectivity a bit. We can not even get the rotation period. I thought we had that ten weeks ago.

While the scientists knew that Ultima Thule would reveal his secrets only in the last days (or hours) of the flyby, the still unanswered questions caused the members of the New Horizons team to join in their creative sides.

"Our team has created small clay figures (guesses) that we believe are based on current information today," said Hal Weaver, a New Horizons project scientist at the Johns Hopkins University Applied Physics Laboratory New Horizons was built and is home to the mission control center.

Yet scientists believe they are beginning to recognize some details.

Ultima Thule is just starting to break up with the New Horizons LORRI imaging camera. The object was previously regarded only as a point of light – a single pixel in the field of view of the camera. This will change quickly as the probe approaches at 14,000 km / s (32,000 miles per second).

The target is now almost 2 pixels wide, but that's still not enough to resolve its shape.

"How fast is it turning? A few hours, dozens of hours or days? "Weaver said.

" There are hints, an indication that this might be a fast rotator, "said Weaver." The little bit we've got out suggests that it may turn quite fast, but we were up and down on the team, believe it or not. "

New Horizons project scientist Hal Weaver talks to reporters on Sunday at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland Credit: Stephen Clark / Spaceflight Now

If Ultima Thule spins relatively fast, that would be good news for researchers looking for their first glimpse of such a primitive world: a fast rotator would show New Horizons more of its surface during the flyby. [19659003] One of the key puzzles in the approach to Ultima Thule was that New Horizons has not observed any light curve or brightness change.

Expect scientists that Ultima Thule became darker and brighter on rotation. New Horizons has found no change.

"We thought as we came in and systematically observed it since mid-September. We would get a so-called light curve that shows us the variation in brightness of Ultima Thule that would tell us something about the shape," said Weaver. [19659005] "We have systematically made these observations, and hope to do so, transform these observations into a shape model of Ultima Thule, but each time we went back and made observations, they were simply completely flat."

"So it's possible It could be anywhere in space – the pivot – but it is an unusual circumstance to point at us. "

" So it may be that it is very elongated is what we mean by measurements of stellar occultation, "He said, referring to observations made as Ultima Thule's light from a background star Earth temporarily blocked, which allowed the scientists to impose restrictions on their shape and size.

Cathy Olkin, associate project scientist at the Southwest Research Institute, agreed

"I think based on the occultation result we have seen a clear signature that either" elongated or two lobes … I do not think we have anything

"I think we will see that we focus on the object, which is one way to reconcile the fact that there is no light curve visible on that object Over time, we do not see any variation in the light. "

Scientists believe that 4.5 billion years ago, Ultima Thule was a relic from the early solar system, a type of object known as the" cold classic, " because it has remained roughly the same orbit in which it has formed.The discoveries will open a new window in relation to the emergence and development of all planetary systems, said Jason Kalirai, Executive Director of APL's Civil Space Mission.

"It is absolutely a fundamental breakthrough in science," said astrophysicist Kalirai.

Weaver said New Year's meeting with Ultima Thule is a unique event for most people on the New Horizons team – due to the time needed to prepare for a space mission and travel from Earth to the Kuiper belt [19659003] New Horizons launched from Cape Canaveral on January 19, 2006, received a Jupiter gravity aid on February 28, 2007, and reached Pluto on July 14, 2015. Weaver called Pluto the gatekeeper of the Kuiper belt a ring of icy primeval orbits that orbit Neptune extend.

Pluto is the largest known object in the Kuiper belt, which scientists believe has short-period comets.

The Kuiper belt lies in the so-called "third zone" of our solar system, the terrestrial planets (inner zone) and gas giants (middle zone). This huge region contains billions of objects, including comets, dwarf planets such as Pluto and "planetesimals" such as Ultima Thule. It is assumed that the objects in this region are frozen in time – relics left over from the formation of the solar system. Credit: NASA / Johns Hopkins University of Applied Physics Laboratory / Southwest Research Institute

"There's nothing else in the books to do that," Weaver said.

"I do not think I'm alive The next cold classic Kuiper belt object has been found, so we're all looking forward to this flyby. In this regard, this is the limit of planetary science. As a civilization, we enter this third zone of the solar system, which was first discovered in the early 1990s.

Scientists have brought sleeping bags and pillows And even a tent to camp here at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, while New Horizons approaches Ultima Thule – his next destination after Pluto.

Alice Hope's Mission Operations Manager Alice Bowman said she had started up at 3 am EST to receive the latest navigation update and help prepare a "knowledge update" for the spacecraft uplink.

The update changed the timing of the sequence of images and data collected during the flight. Only two seconds pass, but that's enough to make some adjustments to make sure the cameras and sensors are in during the one-shot meeting Get the best possible information with Ultima Thule.

"This last day has probably been The most intense for us," said Bowman.

"Whatever it takes, we're here to explore and we're happy to spend the night, if that's it ", she said.

New Horizons is on the right track for his encounter with Ultima Thule, and Bowman tweeted on Sunday evening that the" Knowledge Update "was successfully received by the spacecraft after taking 6 hours and 8 minutes In fact, the final navigation update of Ultima Thule images taken with the LORRI camera aboard the spacecraft shows that New Horizons is about 30 kilometers from its target point, which is 3,500 kilometers from the target object.

Not bad for a mission that spans almost 13 years from the launch pad

It is not expected that additional commands will be sent to the spacecraft before the flyby.

Pure hopeless New Horizons will be the result of astrodynamics its closings will reach t point Ultima Thule at 12.33 pm EST (0533 GMT) on Tuesday, New Year's Day. About four hours later, the spacecraft will interrupt its observations to turn its 2.1 meter (2.1 meter) antenna toward Earth to make a call home.

NASA's Deep Space Network Antenna, a 70-meter-long Antenna Antenna Near Madrid, signals are received more than six hours later at 10:29 EST (1529 GMT). But the best pictures – with Ultima Thule spanning hundreds of pixels – will arrive on Earth late Tuesday and are expected to be released to the public on Wednesday afternoon.

The black-and-white LORRI camera is programmed to take around 1,500 pictures during the flyby. The other instruments aboard New Horizons capture color images, measure the composition of Ultima Thule, and record infrared data.

The flyby command sequence is already being executed by the spacecraft. Because of the great distance between Earth and Ultima Thule, scientists and engineers are unyielding for the encounter.

New Horizons has already loaded instructions into his computer that can be used to eliminate last minute perturbations and continue the data capture sequence. 19659003] "At this time, the navigation effort is effectively completed," said Marc Buie, member of the New Horizons team at the Southwest Research Institute. "It's party time from here."

The last beam that actually modified New Horizons' trajectory was completed on December 18, and there's no way to make a course correction as Flyby-Fast approaches. [19659003] Buie cited the team observing Ultima Thule during two star cultions when the object passed between two stars and Earth in July 2017 and August 2018.

These observations gave the scientists an idea of ​​the shape of Ultima Thule, which may have been suggested to Buie to be in the shape of a peanut, at least according to the coverage data. Some scientists believe that Ultima Thule may be a binary pair of objects, but Buie says he has ruled out this possibility due to recent occultation measurements in August.

"We just have to be patient and wait for the pictures to come and we see more and more pixels," said Buie.

Email to the author.

Follow Stephen Clark on Twitter @ StephenClark1 .


Source link