KBO Chasers


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The Occultations

  • June 3, 2017
    The New Horizons mission team traveled to Argentina and South Africa in the quest for a rare glimpse from Earth of their next target: a small Kuiper Belt object, or KBO. Did they find any hazards such as rings or moons?
  • July 10, 2017
    On July 10, NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) used its powerful 100-inch (2.5-meter) telescope to probe the space around MU69 for debris that might present a hazard to New Horizons as it flies by in 18 months.
  • July 17, 2017
    On July 17, the Hubble Space Telescope checked for debris around MU69, while team members set up another groundbased "fence line" of small mobile telescopes along the predicted ground track of the occultation shadow in southern Argentina to try to better constrain, or even determine, the size of MU69.

KBO Chasers

August 3, 2017New Horizons' Next Target Just Got a Lot More Interesting

One artist’s concept of Kuiper Belt object 2014 MU69, the next flyby target for NASA’s New Horizons mission. This binary concept is based on telescope observations made at Patagonia, Argentina on July 17, 2017 when MU69 passed in front of a star. New Horizons scientists theorize that it could be a single body with a large chunk taken out of it, or two bodies that are close together or even touching.

Second artist’s concept of Kuiper Belt object 2014 MU69, which is the next flyby target for NASA’s New Horizons mission. Scientists speculate that the Kuiper Belt object could be a single body (above) with a large chunk taken out of it, or two bodies that are close together or even touching.

Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/Alex Parker

Could the next flyby target for NASA’s New Horizons spacecraft actually be two targets?

New Horizons scientists look to answer that question as they sort through new data gathered on the distant Kuiper Belt object (KBO) 2014 MU69, which the spacecraft will fly past on Jan. 1, 2019. That flyby will be the most distant in the history of space exploration, a billion miles beyond Pluto.

The ancient KBO, which is more than four billion miles (6.5 billion kilometers) from Earth, passed in front of a star on July 17. A handful of telescopes deployed by the New Horizons team in a remote part of Patagonia, Argentina, were in the right place at the right time to catch its fleeting shadow — an event known as an occultation – and were able to capture important data to help mission flyby planners better determine the spacecraft trajectory and understand the size, shape, orbit and environment around MU69.

Based on these new occultation observations, team members say MU69 may not be not a lone spherical object, but suspect it could be an “extreme prolate spheroid” – think of a skinny football – or even a binary pair. The odd shape has scientists thinking two bodies may be orbiting very close together or even touching – what’s known as a close or contact binary – or perhaps they’re observing a single body with a large chunk taken out of it.

The size of MU69 or its components also can be determined from these data. It appears to be no more than 20 miles (30 kilometers) long, or, if a binary, each about 9-12 miles (15-20 kilometers) in diameter.

“This new finding is simply spectacular. The shape of MU69 is truly provocative, and could mean another first for New Horizons going to a binary object in the Kuiper Belt,” said Alan Stern, mission principal investigator from the Southwest Research Institute (SwRI) in Boulder, Colorado. “I could not be happier with the occultation results, which promise a scientific bonanza for the flyby.”

The July 17 stellar occultation event that gathered these data was the third of a historic set of three ambitious occultation observations for New Horizons. The team used data from the Hubble Space Telescope and European Space Agency’s Gaia satellite to calculate and pinpoint where MU69 would cast a shadow on Earth's surface. “Both of these space satellites were crucial to the success of the entire occultation campaign,” added Stern.

Said Marc Buie, the New Horizons co-investigator from SwRI who led the observation campaign, "These exciting and puzzling results have already been key for our mission planning, but also add to the mysteries surrounding this target leading into the New Horizons encounter with MU69, now less than 17 months away.”

Follow the mission and observation campaign at the NASA New Horizons website and the mission's KBO Chasers page.


July 19, 2017NASA's New Horizons Team Strikes Gold in Argentina

Marc Buie, New Horizons occultation campaign lead, holds up five fingers to represent the number of mobile telescopes in Argentina initially believed to have detected the fleeting shadow of 2014 MU69. The New Horizons spacecraft will fly by the ancient Kuiper Belt object on Jan. 1, 2019. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

A primitive solar system object that's more four billion miles (6.5 billion kilometers) away passed in front of a distant star as seen from Earth. Just before midnight Eastern Time Sunday (12:50 a.m. local time July 17), several telescopes deployed by the New Horizons team in a remote part of Argentina were in precisely the right place at the right time to catch its fleeting shadow — an event that's known as an occultation.

In a matter of seconds, the team captured new data on its elusive target, an ancient Kuiper Belt object known as 2014 MU69. Weary but excited team members succeeded in detecting the spacecraft's next destination, in what's being called the most ambitious and challenging ground occultation observation campaign in history.

"So far we have five confirmed occultations," said Marc Buie of the Southwest Research Institute (SwRI) in Boulder, Colorado, holding up five fingers as New Horizons scientists pored over the exhilarating initial data. Buie led a team of more than 60 observers who battled high winds and cold to set up a "picket fence" of 24 mobile telescopes in a remote region of Chubut and Santa Cruz, Argentina. Their goal: to spot the shadow of the mysterious Kuiper Belt object (KBO) that New Horizons will fly by on New Year's Day 2019 – to better understand its size, shape, orbit and the environment around it. Before these observations, only the Hubble Space Telescope successfully detected MU69, and even it had not been able to determine MU69's size or shape.

"It was the most historic occultation on the face of the Earth," said Jim Green, NASA's director of planetary science, in a congratulatory call to the team. "You pulled it off and you made it happen."

The first MU69 occultation campaign scientist to see the telltale signature of MU69 was Amanda Zangari, a New Horizons co-investigator from SwRI, who said, "We nailed it spectacularly."

New Horizons co-investigator Amanda Zangari was the first occultation campaign scientist to see the telltale signature of MU69 while analyzing data from July 17, saying, "We nailed it spectacularly." Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

The New Horizons team enjoyed strong support from Argentinian scientists, government officials, and locals, who went above and beyond to ensure mission success. "I've been calling the people who helped us, our ‘twelfth player,'" Buie said. "The Comodoro Rivadavia community came together and did some amazing things for us." A major national highway was closed for two hours to keep car headlights away. Street lights were turned off to ensure absolute darkness. People like the intendente (or mayor) of the Comodoro parked trucks as wind breaks. "The local people were a major team player," Buie said.

"Planning for this complex astronomical deployment started just a few months ago and although the odds seem daunting – like finding a needle in a haystack – the team succeeded, thanks to the help of institutions like CONAE, and all the goodwill of the Argentinian people. This is another example of how space exploration brings out the best in us," said New Horizons Program Executive Adriana Ocampo.

This was the third of three ambitious occultation observations for New Horizons, and all contributed to the success of the campaign. On June 3, teams in both Argentina and South Africa attempted to observe MU69. On July 10, researchers using NASA's Stratospheric Observatory for Infrared Astronomy, or SOFIA, studied the environment around MU69 while flying over the Pacific Ocean from Christchurch, New Zealand.

When New Horizons flies by it, MU69 will be the most distant object ever explored by a spacecraft, over a billion miles farther from our sun than Pluto. This ancient Kuiper Belt object is not well understood, because it is faint (likely 14-25 miles or 22-40 kilometers across) and so far away. To study this distant object from Earth, the New Horizons team used Hubble Space Telescope and Gaia satellite data to calculate where MU69 would cast a shadow on Earth's surface. Both satellites were crucial to the occultation campaign.

Wink of a star: NASA's New Horizons team trained mobile telescopes on an unnamed star (circled) from a remote area of Argentina on July 17, 2017. A Kuiper Belt object 4.1 billion miles from Earth – known as 2014 MU69 – briefly blocked the light from the background star, in what's known as an occultation. The time difference between frames is 200 milliseconds, or 0.2 seconds. This data will help scientists better measure the shape, size and environment around the object. The New Horizons spacecraft will fly by this ancient relic of solar system formation on Jan. 1, 2019. It will be the most distant object ever explored by a spacecraft. Click here to see a longer version of the occultation. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

It will take weeks for scientists to analyze the many datasets from the multi-faceted campaign. This advance observation is a critical step in flyby planning before the New Horizons spacecraft arrives at MU69 on Jan. 1, 2019.

"This effort, spanning six months, three spacecraft, 24 portable ground-based telescopes, and NASA's SOFIA airborne observatory was the most challenging stellar occultation in the history of astronomy, but we did it!" said Alan Stern, New Horizons principal investigator from SwRI. "We spied the shape and size of 2014 MU69 for the first time, a Kuiper Belt scientific treasure we will explore just over 17 months from now. Thanks to this success we can now plan the upcoming flyby with much more confidence."

To see a video of preparations for the July 17 observations in Argentina: tinyurl.com/KBprep

Follow the mission at the NASA New Horizons website, the mission's KBO Chasers page, and #mu69occ.

The New Horizons team would like to thank all who supported the occultation observations in Argentina, especially the U.S. Embassy in Argentina, GAIA, Hubble Space Telescope, SOFIA, International Occultation Timing Association (IOTA), Ministry of Foreign Affairs, Ministry and Science and Technology, CONAE (Comisión Nacional del Espacio), University of Patagonia, San Juan Bosco, Intendencia of Comodoro Rivadavia, Chubut Argentina, Secretaría de Seguridad and Civil Defense of Chubut and Santa Cruz, Argentine Air Force Meteorological Service, Leoncito Observatory, San Juan, Observatorio Astronomico de Cordoba, Instituto de astronomia Teorica Experimental (IATE), Argentine Amateur Astronomy Association and Empresa Vesprini.


July 19, 2017NASA's New Horizons Team Strikes Gold in Argentina

Marc Buie, New Horizons occultation campaign lead, holds up five fingers to represent the number of mobile telescopes in Argentina initially believed to have detected the fleeting shadow of 2014 MU69. The New Horizons spacecraft will fly by the ancient Kuiper Belt object on Jan. 1, 2019. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

A primitive solar system object that's more four billion miles (6.5 billion kilometers) away passed in front of a distant star as seen from Earth. Just before midnight Eastern Time Sunday (12:50 a.m. local time July 17), several telescopes deployed by the New Horizons team in a remote part of Argentina were in precisely the right place at the right time to catch its fleeting shadow — an event that's known as an occultation.

In a matter of seconds, the team captured new data on its elusive target, an ancient Kuiper Belt object known as 2014 MU69. Weary but excited team members succeeded in detecting the spacecraft's next destination, in what's being called the most ambitious and challenging ground occultation observation campaign in history.

"So far we have five confirmed occultations," said Marc Buie of the Southwest Research Institute (SwRI) in Boulder, Colorado, holding up five fingers as New Horizons scientists pored over the exhilarating initial data. Buie led a team of more than 60 observers who battled high winds and cold to set up a "picket fence" of 24 mobile telescopes in a remote region of Chubut and Santa Cruz, Argentina. Their goal: to spot the shadow of the mysterious Kuiper Belt object (KBO) that New Horizons will fly by on New Year's Day 2019 – to better understand its size, shape, orbit and the environment around it. Before these observations, only the Hubble Space Telescope successfully detected MU69, and even it had not been able to determine MU69's size or shape.

"It was the most historic occultation on the face of the Earth," said Jim Green, NASA's director of planetary science, in a congratulatory call to the team. "You pulled it off and you made it happen."

The first MU69 occultation campaign scientist to see the telltale signature of MU69 was Amanda Zangari, a New Horizons co-investigator from SwRI, who said, "We nailed it spectacularly."

New Horizons co-investigator Amanda Zangari was the first occultation campaign scientist to see the telltale signature of MU69 while analyzing data from July 17, saying, "We nailed it spectacularly." Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

The New Horizons team enjoyed strong support from Argentinian scientists, government officials, and locals, who went above and beyond to ensure mission success. "I've been calling the people who helped us, our ‘twelfth player,'" Buie said. "The Comodoro Rivadavia community came together and did some amazing things for us." A major national highway was closed for two hours to keep car headlights away. Street lights were turned off to ensure absolute darkness. People like the intendente (or mayor) of the Comodoro parked trucks as wind breaks. "The local people were a major team player," Buie said.

"Planning for this complex astronomical deployment started just a few months ago and although the odds seem daunting – like finding a needle in a haystack – the team succeeded, thanks to the help of institutions like CONAE, and all the goodwill of the Argentinian people. This is another example of how space exploration brings out the best in us," said New Horizons Program Executive Adriana Ocampo.

This was the third of three ambitious occultation observations for New Horizons, and all contributed to the success of the campaign. On June 3, teams in both Argentina and South Africa attempted to observe MU69. On July 10, researchers using NASA's Stratospheric Observatory for Infrared Astronomy, or SOFIA, studied the environment around MU69 while flying over the Pacific Ocean from Christchurch, New Zealand.

When New Horizons flies by it, MU69 will be the most distant object ever explored by a spacecraft, over a billion miles farther from our sun than Pluto. This ancient Kuiper Belt object is not well understood, because it is faint (likely 14-25 miles or 22-40 kilometers across) and so far away. To study this distant object from Earth, the New Horizons team used Hubble Space Telescope and Gaia satellite data to calculate where MU69 would cast a shadow on Earth's surface. Both satellites were crucial to the occultation campaign.

Wink of a star: NASA's New Horizons team trained mobile telescopes on an unnamed star (circled) from a remote area of Argentina on July 17, 2017. A Kuiper Belt object 4.1 billion miles from Earth – known as 2014 MU69 – briefly blocked the light from the background star, in what's known as an occultation. The time difference between frames is 200 milliseconds, or 0.2 seconds. This data will help scientists better measure the shape, size and environment around the object. The New Horizons spacecraft will fly by this ancient relic of solar system formation on Jan. 1, 2019. It will be the most distant object ever explored by a spacecraft. Click here to see a longer version of the occultation. Credits: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute/ Adriana Ocampo

It will take weeks for scientists to analyze the many datasets from the multi-faceted campaign. This advance observation is a critical step in flyby planning before the New Horizons spacecraft arrives at MU69 on Jan. 1, 2019.

"This effort, spanning six months, three spacecraft, 24 portable ground-based telescopes, and NASA's SOFIA airborne observatory was the most challenging stellar occultation in the history of astronomy, but we did it!" said Alan Stern, New Horizons principal investigator from SwRI. "We spied the shape and size of 2014 MU69 for the first time, a Kuiper Belt scientific treasure we will explore just over 17 months from now. Thanks to this success we can now plan the upcoming flyby with much more confidence."

To see a video of preparations for the July 17 observations in Argentina: tinyurl.com/KBprep

Follow the mission at the NASA New Horizons website, the mission's KBO Chasers page, and #mu69occ.

The New Horizons team would like to thank all who supported the occultation observations in Argentina, especially the U.S. Embassy in Argentina, GAIA, Hubble Space Telescope, SOFIA, International Occultation Timing Association (IOTA), Ministry of Foreign Affairs, Ministry and Science and Technology, CONAE (Comisión Nacional del Espacio), University of Patagonia, San Juan Bosco, Intendencia of Comodoro Rivadavia, Chubut Argentina, Secretaría de Seguridad and Civil Defense of Chubut and Santa Cruz, Argentine Air Force Meteorological Service, Leoncito Observatory, San Juan, Observatorio Astronomico de Cordoba, Instituto de astronomia Teorica Experimental (IATE), Argentine Amateur Astronomy Association and Empresa Vesprini.


July 11, 2017SOFIA in Right Place at Right Time to Study Next New Horizons Flyby Object

Credit: NASA

NASA's airborne observatory, SOFIA, was in the right place at the right time to study the environment around a distant Kuiper Belt object, 2014 MU69, which is the next flyby target for NASA's New Horizons spacecraft.

The team onboard SOFIA was able to position the flying telescope precisely where the data from NASA's Hubble Space Telescope and the European Space Agency's Gaia satellite indicated the center of the shadow would be, at precisely the right time.

"This was the most challenging occultation observation because MU69 is so small and so distant," said Kimberly Ennico Smith, SOFIA project scientist. "Working with the New Horizons researchers onboard, our instrument team, and our flight crew, we optimized our observing strategy and collected data throughout the entire occultation event. We're eagerly anticipating the results of the data analysis."

The mission team will analyze that data over the next few weeks, looking especially for any rings or debris around MU69 that might present problems for New Horizons when the spacecraft flies past the Kuiper Belt object on January 1, 2019.


July 10, 2017SOFIA to Make Advance Observations of Next New Horizons Flyby Object

On July 10, researchers using NASA’s Stratospheric Observatory for Infrared Astronomy, or SOFIA, will attempt to study the environment around a distant Kuiper Belt Object, 2014 MU69, which is the next flyby target for NASA’s New Horizons spacecraft.

When New Horizons flies by it, MU69 will be the most distant object ever explored by a spacecraft, over a billion miles farther from our sun than Pluto. This ancient Kuiper Belt object is not well understood because it is faint, small (likely 12-25-mile [20-40-kilometer] across or even smaller according to recent ground-based observations), and very far away (approximately 4.1 billion miles from Earth).

Ready to fly: NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA) is prepared for flight in Christchurch, New Zealand, on July 9, 2017. On July 10 SOFIA will use its powerful telescope to attempt to study the environment around a distant Kuiper Belt object, 2014 MU69, which is the next flyby target for the New Horizons spacecraft. (Credit: Geoff Haines-Stiles)

To study this distant object from Earth, the New Horizons team have used data from NASA’s Hubble Space Telescope and the European Space Agency' 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. Based on this calculation -- which determined the shadow would pass over open water in the Pacific -- the SOFIA team will attempt to position the aircraft in the center of the shadow, pointing SOFIA’s telescope at MU69 when it passes in front of the background star. The New Horizons team will then analyze the data obtained with SOFIA to see how the light from the star changes as MU69 passes in front of it.

These observations will allow researchers to better understand the hazardous environment created by rings or other debris that may orbit MU69. This advance observation is a critical step in flyby planning before the New Horizons spacecraft arrives at MU69 on January 1, 2019. The SOFIA observations on July 10 are another way SOFIA has been able to support the New Horizons mission, as it did in June 2015, before New Horizons made its historic flyby of Pluto.

"Back then, SOFIA was able to be in the center of Pluto’s shadow during the occultation event on June 29, 2015, providing a valuable atmospheric dataset in support of New Horizons," said Kimberly Ennico Smith, SOFIA project scientist. "This year we’re continuing that collaboration, as SOFIA can provide information that will be critical to the New Horizons team’s plans for the MU69 flyby in 2019."

From left, New Horizons observation team members Marc Buie, Eliot Young and Simon Porter discuss the mission to observe Kuiper Belt object 2014 MU69 with Paul Newton, pilot of NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA), on July 10, 2017. (Credit: Geoff Haines-Stiles)

There are differences that make SOFIA’s observations for the MU69 flyby more difficult than those done in support of the Pluto flyby. Because of its small size and large distance from Earth, the shadow cast by MU69 is about 100 times smaller than that of Pluto. This small size, relative to the positional accuracy of the aircraft, makes the planned observation very challenging for SOFIA. The small size of the shadow and the uncertainty in its position means that SOFIA might not succeed in flying through the shadow. Still, SOFIA may be able to provide important data given the plane’s vantage point from above the clouds, which removes bad weather as an observation obstacle, and given that the shadow falls in the middle of the Pacific Ocean, where it is inaccessible to smaller, ground-based telescopes.

Follow SOFIA and its missions across all social media platforms – @SOFIAtelescope, and keep up to date on the New Horizons mission by following their team blogs, the NASA New Horizons website, the mission’s KBO Chasers page, and #mu69occ.

Learn more about SOFIA at http://www.nasa.gov/sofia


June 13, 2017New Horizons Team Digs into New Data on Next Flyby Target

Paul Maley and Ted Blank, both of the International Occultation Timing Association, observe the occultation of Kuiper Belt object 2014 MU69 on the morning of June 3, 2017, from the Karoo desert near Vosburg, South Africa. Their target field — containing both Pluto and MU69 — is in the portion of the Milky Way seen here, in the constellation of Sagittarius. They positioned their telescope next to a small church, shielding it from winds that could arise during the cold winter night. NASA's New Horizons spacecraft will fly past MU69 on Jan. 1, 2019. Credit: NASA/JHUAPL/SwRI/Henry Throop


In Argentina, New Horizons scientist Alex Parker sets up to begin collecting data on the stellar occultation of 2014 MU69. Credit: Kai Getrost

It was the most technically-challenging and complex stellar occultation observation campaign ever attempted: At least 54 observing teams with dozens of telescopes dispatched across two continents, positioned to catch a rare, two-second glimpse of a small, distant Kuiper Belt object passing in front of a star. And it wasn't just any KBO — it was the next flyby target of NASA's pioneering New Horizons mission.

Overnight on June 2-3, about two-dozen members of the New Horizons team and other observers in Argentina and South Africa were hoping to capture the fleeting starlit shadow of 2014 MU69, which the New Horizons spacecraft will explore in a flyby on New Year's Day 2019.

"The stars aligned for this observing campaign, which was implemented expertly by the team," said New Horizons Program Executive Adriana Ocampo at NASA Headquarters in Washington, D.C. "It's amazing how classical astronomy – from small telescopes to some of the most advanced observatories on Earth -- is helping New Horizons plan its next flyby, and it shows how truly global space exploration is."

All 54 telescope teams collected data, reported mission Principal Investigator Alan Stern, adding that team scientists started digging into that data when they returned home last week.

"A tremendous amount had to go right to correctly execute such a massive observation campaign, but it did," said Stern, of the Southwest Research Institute (SwRI) in Boulder, Colorado. "The main goal of these observations was to search for hazards; the secondary objective was to try to glimpse the occultation of MU69 itself, in order to learn its precise size. Scouring all the dozens of datasets for these two objectives is going to take us a few weeks."

New Horizons team members and collaborators rehearse to observe the occultation of Kuiper Belt object 2014 MU69 outside of Clanwilliam, South Africa. The clouds seen here caused the team to choose to split up: half stayed at this site for the event the following night, while half traveled 300 miles (500 kilometers) to the northeast in a bid to avoid the clouds. As it turned out, both teams saw mostly clear skies during the critical moments of the occultation. NASA's New Horizons spacecraft will fly past MU69 on Jan. 1, 2019. Credit: NASA/JHUAPL/SwRI/Henry Throop


Four members of the South African observation team scan the sky while waiting for the start of the 2014 MU69 occultation, early on the morning of June 3, 2017. The target field is in the Milky Way, seen here from their observation site in the Karoo desert near Vosburg, South Africa. They used portable telescopes to observe the event, as MU69, a small Kuiper Belt object and the next flyby target of NASA's New Horizons spacecraft, passed in front of a distant star. Credits: NASA/JHUAPL/SwRI/Henry Throop

Near-Perfect Positioning

Marc Buie, the New Horizons SwRI co-investigator who led the campaign, stressed that data from the European Space Agency's Gaia mission and the Hubble Space Telescope were critical to planning the observations. "Without Gaia and Hubble, I doubt we could have succeeded so well at this," Stern agreed, "Gaia and Hubble were crucial to this success and we thank them both."

Combining Gaia star positions with Hubble images provided the information needed to predict the narrow path of MU69's shadow across Earth. "The Gaia star data has been critical this entire operation," Buie said. "Without it, there was no way we could have predicted such an accurate path."

Observing by Air and Land

New Horizons has two more chances to observe stellar occultations of MU69 this summer, on July 10 and July 17. On July 10 the team will employ the powerful 100-inch (2.5-meter) telescope on NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA); the plane's vantage point from above the clouds will remove bad weather as an observation obstacle, and SOFIA should be able to provide better data than the smaller telescopes used in the occultation just completed. Airborne, SOFIA will provide the best vantage point to observe the July 10 occultation since the shadow falls in the middle of the Pacific Ocean.

On July 17, New Horizons team members will redeploy with two-dozen small mobile telescopes (40 centimeters in diameter) to far southern lands in Patagonia, Argentina to observe the third and final event, which offers a much brighter star to probe even more deeply for debris around MU69.

Follow all of these observations and more about New Horizons and its ongoing journey of exploration in the Kuiper Belt on Facebook [link to https://www.facebook.com/new.horizons1/] and Twitter using hashtag #mu69occ. Watch for team blogs and images on the NASA New Horizons website and the mission's KBO Chasers page.


Projected path of the 2014 MU69 occultation shadow, on July 10 (left) and July 17, 2017 (right). Credits: Larry Wasserman/Lowell Observatory


May 25, 2017New Horizons Deploys Global Team for Rare Look at Next Flyby Target

On New Year's Day 2019, more than 4 billion miles from home, NASA's New Horizons spacecraft will race past a small Kuiper Belt object known as 2014 MU69 – making this rocky remnant of planetary formation the farthest object ever encountered by any spacecraft.

First look: Projected path of the 2014 MU69 occultation shadow, across South America and the southern tip of Africa, on June 3. Credits: Larry Wasserman/Lowell Observatory

But over the next six weeks, the New Horizons mission team gets an "MU69" preview of sorts – and a chance to gather some critical encounter-planning information – with a rare look at their target object from Earth.

On June 3, and then again on July 10 and July 17, MU69 will occult – or block the light from – three different stars, one on each date. To observe the June 3 "stellar occultation," more than 50 team members and collaborators are deploying along projected viewing paths in Argentina and South Africa. They'll fix camera-equipped portable telescopes on the occultation star and watch for changes in its light that can tell them much about MU69 itself.

"Our primary objective is to determine if there are hazards near MU69 – rings, dust or even satellites – that could affect our flight planning," said New Horizons Principal Investigator Alan Stern, of Southwest Research Institute (SwRI) in Boulder, Colorado. "But we also expect to learn more about its orbit and possibly determine its size and shape. All of that will help feed our flyby planning effort."

What Are They Looking at?

In simplest terms, an astronomical occultation is when something moves in front of, or occults, something else. "When the moon passes in front of the sun and we have a solar eclipse, that's one kind of occultation," said Joel Parker, a New Horizons co-investigator from SwRI. "If you're in the path of an eclipse, it means you're in the path of the shadow on Earth that's created by the moon passing between us and the sun. If you're standing in the right place at the right time, the solar eclipse can last up to a few minutes."

The team will have no such luxury with the MU69 occultations. Marc Buie, the New Horizons co-investigator from SwRI who is leading the occultation observations, said that because MU69 is so small – thought to be about 25 miles (40 kilometers) across – the occultations should only last about two seconds. But scientists can learn a lot from even that, and observations from several telescopes that see different parts of the shadow can reveal information about an object's shape as well as its brightness.

New Horizons team members prepare one of the new 16-inch telescopes for deployment to occultation observation sites in Argentina and South Africa. Credits: Kerri Beisser

A Space Challenge

The mission team has 22 new, portable 16-inch (40-centimeter) telescopes at the ready, along with three other portables and over two-dozen fixed-base telescopes that will be located along the occultation path through Argentina and South Africa. But deciding exactly where to place them was a challenge.

This particular Kuiper Belt object was discovered just three years ago, so its orbit is still largely unknown. The team used star-position data from the extensive catalog of the European Space Agency's Gaia mission and Hubble Space Telescope position measurements of MU69 to predict the narrow occultation path. Without a precise fix on the object's position – or on the exact path its narrow shadow might take across Earth – the team is spacing the telescope teams along "picket fence lines," one every 6 to 18 miles (10 or 25 kilometers), to increase the odds that at least one or more of the portable telescopes will catch the center of the event and help determine the size of MU69.

The other telescopes will provide multiple probes for debris that could be a danger to the fast-moving New Horizons spacecraft when it flies by MU69 at about 35,000 miles per hour (56,000 kilometers per hour), on Jan. 1, 2019.

"Deploying on two different continents also maximizes our chances of having good weather," said New Horizons Deputy Project Scientist Cathy Olkin, from SwRI. "The shadow is predicted to go across both locations and we want observers at both, because we wouldn't want a huge storm system to come through and cloud us out — the event is too important and too fleeting to miss."

The team gets help from above for the July 10 occultation, adding the powerful 100-inch (2.5-meter) telescope on NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA). Enlisting SOFIA, with its vantage point above the clouds, takes the bad weather factor out of the picture. The plane also should be able to improve its measurements by maneuvering into the very center of the occultation shadow.

Insight for Encounter Planning

Any information on MU69, gathered from the skies or on the ground, is welcome. Carly Howett, deputy principal investigator of New Horizons' Ralph instrument, of SwRI, said so little is known about MU69 that the team is planning observations of a target it doesn't fully understand – and time to learn more about the object is short. "We were only able to start planning the MU69 encounter after we flew by Pluto in 2015," she said. "That gives us two years, instead of almost seven years we had to plan the Pluto encounter. So it's a very different and, in many ways, more challenging flyby to plan."

If weather cooperates and predicted targeting proves on track, the upcoming occultation observations could provide the first precise size and reflectivity measurements of MU69. These figures will be key to planning the flyby itself – knowing the size of the object and the reflectivity of its surface, for example, helps the team set exposure times on the spacecraft's cameras and spectrometers.

"Spacecraft flybys are unforgiving," Stern said. "There are no second chances. The upcoming occultations are valuable opportunity to learn something about MU69 before our encounter, and help us plan for a very unique flyby of a scientifically important relic of the solar system's era of formation."

Follow the observations in Argentina, South Africa and on board SOFIA on Facebook and Twitter using #mu69occ.

Team Members Blog

07/17/17: Pictures at Occulation


07/16/17: “Yep, July 17th 2017 is a day that will live in astronomy (and light) - the 3rd and final initiative of this summer’s MU69 occultation campaign. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"


07/16/17: “Flawless practice night. Our treat at the end was a beautiful moonrise over the ocean.” Marc Buie


07/15/17: Brian Keeney, left, Kelsi Singer (right) and others scout for locations to site the 20 plus telescopes being deployed for the July 17th occultation. Good sites should be sheltered from the wind, and away from roads where car and truck lights might interfere with the observations. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

07/15/17: The astronomical calculations that determine where an occultation can be observed are complex, but the on-the-ground logistics are almost as complicated. Communication between team leader Marc Buie (seated, center, back to he camera) and all 50 observers is essential. Hence daily "All Hands Meetings" at the Palazzo Hotel in Comodoro Rivadavia. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

07/15/17: Birds' eye view of the telescope boxes being unloaded from the ARGMOVES truck which brought them south from Buenos Aires. Each team has four boxes to load on and off their SUVs for each night's practice and, of course, for the all-important occultation night of July 17th. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"


Wind Break

07/14/17: Since Comodoro Rivadavia has the nickname of "The Capital of The Wind" and SwRI's 16-inch telescopes are vulnerable to gusts, creating makeshift but effective wind-breaks from available supplies is very important. Says occultation volunteer Jason Mackie, "Today we went shopping for materials to build the wind-breaks for the telescopes. This meant that we had to buy roughly 1/3 km of tarp material, 1/3 km of steel, and 1.5 km of rope! Seriously." Apparently New Horizons has bought up ALL tarps in CR. Hoping they work! Credit: Sam Chevallier for GHSPi/"Pluto & Beyond"


Telescope Check

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07/14/17: In the hotel garage, the telescopes are unpacked and checked for the first time in Comodoro Rivadavia. It's literally a whirlwind of activity for team leader Marc Buie, New Horizons Principal Investigator Alan Stern and Co-Investigator Simon Porter, fresh off the plane from the July 10 SOFIA observations. With 25 telescopes and 50 volunteers, there are just enough researchers and volunteers on hand. They'll be busy all through July 17!


07/13/17: Today we went shopping for materials to build the wind-breaks for the telescopes. We are building twenty of them. - Jason Mackie


07/11/2017: "Observing on SOFIA was an amazing experience. Alan made the flight, just barely. When we took off the forecast for our return to Christchurch was for heavy fog which would likely require a diversion to Auckland for the night. We all raced off to the hotel to grab out bags just in case so that we could still catch our flights out from Auckland the next day. The flight went really well and the crew did an amazing job getting us to the right place at the right time. We now have data to process, details when we have them. On the way back we didn't know our destination airport until ~30 minutes before landing but we did make it back to Christchurch after all. I've got plenty to keep me busy on the way to Argentina now. The pursuit of 2014MU69 continues." MARC BUIE


07/10/2017: Onboard with SOFIA – it was a long flight but with some spectacular scenes, taking a moment to enjoy the views

Onboard with SOFIA

Credit: Geoff Haines-Stiles


07/09/2017: Pre-flight meetings all complete -ready to board SOFIA

Pre-flight meetings all complete -ready to board SOFIA

Credit: Geoff Haines-Stiles


07/08/2017: The day before the SOFIA flight: Lots of clouds but nothing to worry about. Soon will be flying high above them.

Clouds the day before the SOFIA flight

Credit: Geoff Haines-Stiles


06/03/2017: Clear skies and successful occultation observations in Argentina and S. Africa; can't wait to start digging into the data and also to continue planning for the July 10th and 17th events!


"It is now the calm-before-the-storm time. All the prep, all the training, all the coaching, all the repairs, are done. Now success is in the hands of the collective, an amazing human experience, where we accomplish great things as a team. Scary, perhaps, but exhilarating all the same." -Marc Buie

What will happen tonight? Will the weather forecast prove correct with 90% cloud cover in Clanwilliam or will we miraculously have gloriously-clear weather? Will all the last-minute efforts of the all-night-driving ZA-east teams prove unnecessary or will their diligence end up saving the day? Which team (if any) will actually catch the occultation?

Read more »

Photo Gallery

Click on the categories below for more details.

Click on the images below for more details.

“You don’t need a weatherman to know which way the wind blows…” (yes, we’re partial to Nobel Laureate Bob Dylan) but in Patagonia you do need to know how to keep the wind off of the telescopes. Tarps, trucks and ingenuity are the answer. A traditional salutation in astronomy is “Clear Skies.” To which we add, late in the day of July 16th, “Calm Winds”!!! Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

“PL” - that means PL-uto. And P-erceval L-owell. And Pretty Lively. And Persistence (a favorite word around New Horizons) and Luck - which comes most easily to those who work hard to make it so. That’s Mission PI, Alan Stern in the center; SwRI logistics lead, Peter Tamblyn, to right, and apologies to whoever it is on the left! Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

Tools of the Trade for the July 17th Argentina occultation - from top left. Batteries - pretty obvious. Gloves - temps below freezing, so of course. Knife? Just in case ropes around those tarps start flapping. Hand warmer, d’accord. Kindling wood and “Fosforos de madera” - wooden matches - in case an emergency fire is needed to bring fingers that have to type on laptops back to life. So the New Horizons project includes the Hubble Space Telescope, ESA’s Gaia satellite, NASA’s SOFIA airborne observatory… and these very down to Earth supplies. Stay warm, not frosty, Comorodo Rivadavia! Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

“Yep, July 17th 2017 is a day that will live in astronomy (and light) - the 3rd and final initiative of this summer’s MU69 occultation campaign. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

How did the New Horizons team get their spacecraft so successfully and spectacularly to Pluto? “Practice, practice, practice.” Now that’s exactly what the occultation team has been doing in Patagonia, getting ready for the 3rd and final night of observations, July 17th, 2017. They pretty much took over a parking lot for a final group practice last night, planning to share Lessons Learned at 5pm local tonight (July 16) in an All Hands meeting. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Astronomy captures data with light, and here an observer’s red night light - designed not to interfere with night vision during the actual event - traces the dance of telescope and human as they practice for the July 17th occultation. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Astronomy captures data with light, and here an observer’s night light traces the dance of telescope and human as they practice for the July 17th occultation. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

The skies are clear, a good thing, but that makes observing challenging in the Patagonian winter. And wind continues to be a problem close to Comodoro Rivadavia, nicknamed “The Capital of Wind.” So the SwRI/NASA team, with many amateur astronomy volunteers contributing as well, put their SUVs and loaned trucks from local government - whose support is much appreciated - to work as wind breaks. Several of the team plan to hang tarps as additional protection. Occultation campaigns are always about responding to last minute and unanticipated problems, and solving them. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Bob Dylan sings, "Come in, she said/I'll give ya shelter from the storm.” And our our team of hardy KBO Chasers are taking advantage of whatever shelter they can find against gusty Patagonian winds. The 16” telescopes, developed for amateur astronomers, are capable of delivering professional results, but can wobble. So the observers take whatever steps they can to fight back. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Bob Dylan sings, "Come in, she said/I'll give ya shelter from the storm.” And our our team of hardy KBO Chasers are taking advantage of whatever shelter they can find against gusty Patagonian winds. The 16” telescopes, developed for amateur astronomers, are capable of delivering professional results, but can wobble. So the observers take whatever steps they can to fight back. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Friday Night Practice. Photo Kai Getrost

Scouting Observation Sites. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

The caravan departs on practice night #2. Photo Ted Blank

Telescope assembly at the Rugby Field. Photo Ted Blank

Brian Keeney, left, Kelsi Singer (right) and others scout for locations to site the 20 plus telescopes being deployed for the July 17th occultation. Good sites should be sheltered from the wind, and away from roads where car and truck lights might interfere with the observations. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

The astronomical calculations that determine where an occultation can be observed are complex, but the on-the-ground logistics are almost as complicated. Communication between team leader Marc Buie (seated, center, back to he camera) and all 50 observers is essential. Hence daily "All Hands Meetings" at the Palazzo Hotel in Comodoro Rivadavia. Photo Sam Chevallier, ReWildTV, for GHSPi/"Pluto & Beyond"

Birds' eye view of the telescope boxes being unloaded from the ARGMOVES truck which brought them south from Buenos Aires. Each team has four boxes to load on and off their SUVs for each night's practice and, of course, for the all-important occultation night of July 17th. Photo Alistair Daynes, ReWildTV, for GHSPi/"Pluto & Beyond"

Since Comodoro Rivadavia has the nickname of "The Capital of The Wind" and SwRI's 16-inch telescopes are vulnerable to gusts, creating makeshift but effective wind-breaks from available supplies is very important. Says occultation volunteer Jason Mackie, "Today we went shopping for materials to build the wind-breaks for the telescopes. This meant that we had to buy roughly 1/3 km of tarp material, 1/3 km of steel, and 1.5 km of rope! Seriously." Apparently New Horizons has bought up ALL tarps in CR. Hoping they work! Credit: Sam Chevallier for GHSPi/"Pluto & Beyond"

Click on the images below for more details.

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

It takes

It takes "all eyes" on an occultation to make it work - flight crew and researchers. Credit: Geoff Haines-Stiles

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Alan Stern

Onboard SOFIA.

Onboard SOFIA. Credit: Geoff Haines-Stiles

Onboard SOFIA.

Onboard SOFIA. Credit: Geoff Haines-Stiles

Onboard SOFIA.

Onboard SOFIA. Credit: Geoff Haines-Stiles

SOFIA pre flight mission briefing.

SOFIA pre flight mission briefing. Credit: Geoff Haines-Stiles

SOFIA pre-flight weather briefing by the pilot.

SOFIA pre-flight weather briefing by the pilot. Credit: Geoff Haines-Stiles

SOFIA pre-flight weather briefing by the pilot.

SOFIA pre-flight weather briefing by the pilot. Credit: Geoff Haines-Stiles

SOFIA pre flight mission briefing.

SOFIA pre flight mission briefing. Credit: Geoff Haines-Stiles

SOFIA pre flight mission briefing.

SOFIA pre flight mission briefing. Credit: Geoff Haines-Stiles

SOFIA Briefing with Pilot

Team members meet on June 9, 2017 for SOFIA pre-flight briefings. Credit: Geoff Haines-Stiles

SOFIA Briefing

Team members meet on June 9, 2017 for SOFIA pre-flight briefings. Credit: Geoff Haines-Stiles

Marc explains MU69 mission to pilot

Team members meet on June 9, 2017 for SOFIA pre-flight briefings. Credit: Geoff Haines-Stiles

Clouds the day before the SOFIA flight

The day before the SOFIA flight: Lots of clouds but nothing to worry about. Soon will be flying high above them. Credit: Geoff Haines-Stiles

Click on the images below for more details.

Team members meet on June 1, 2017 to plan that evening's rehearsal at sites that offer the best chance of successfully observing the occultation on June 2 and June 3, 2017. Photo Credit: Geoff Haines-Stiles

Team members meet on June 1 to plan that evening's rehearsal at sites that offer the best chance of successfully observing the occultation on June 2 and June 3, 2017. Photo Credit: Geoff Haines-Stiles

Team members meet on June 1 to plan that evening's rehearsal at sites that offer the best chance of successfully observing the occultation on June 2 and June 3, 2017. Photo Credit: Geoff Haines-Stiles

Telescope staging area in the hotel conference room. Photo Credit: Bill Hanna

View of Mendoza, Argentina. Photo Credit: Geoff Haines-Stiles

The glow of red lights illuminates observers setting up telescopes under a stunning starry sky. Photo Credit: Jack Jewell

Looking at Omega Centauri after practice. Photo Credit: Kai Getrost

All hands meeting and forecast of clearing this evening. Argentina pre-deployment meeting. Photo Credit: GHS

The eve of the big observation –KBO Chasers Argentina Team. Photo Credit: Geoff Haines Stiles

Argentina KBO Chasers –MU69. Photo: Jack Jewell

Preparing to start collecting data in Argentina. Credit: Kai Getrost

Click on the images below for more details.

Observers about to depart Denver for South Africa. Photo Credit: Amanda Zangari

KBO chasers on the bus in South Africa. Photo Credit: Amir Caspi

Observers set up telescopes for an evening test in Cape Town. Photo Credit: Emily Kramer

Setting up for an evening test at the Protea Mowbray within view of Devil's Peak. Photo Credit: Emily Kramer

On the way to Clanwilliam - and, yes, we saw baboons! Photo Credit: Mike Skrutskie

Spectacular last night of dress rehearsal at the Rondberg in South Africa. Photo: Charles Danforth

Scanning the sky while waiting for the start of the 2014 MU69 occultation, in the Karoo desert near Vosburg, South Africa. Credit: Henry Throop

Rehearsing to observe the occultation of MU69 under partly cloudy skies in Clanwilliam, South Africa. Credit: Henry Throop

Wonder woman pose for telescope final take down after the June 3, 2017 observation. Photo: Emily Kramer

Observing the occultation of MU69 near Vosburg, South Africa. Credit: Henry Throop