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Space News Update — January 4, 2019 —

Contents

In the News

Story 1: New Ultima Thule Discoveries from NASA's New Horizons

Story 2: NASA’s OSIRIS-REx Spacecraft Enters Close Orbit Around Bennu,

Breaking Record

Story 3: Dark Matter on the Move

Departments

The Night Sky

ISS Sighting Opportunities

Space Calendar

NASA-TV Highlights

Food for Thought

Space Image of the Week

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1. New Ultima Thule Discoveries from NASA's New Horizons

Data from NASA's New Horizons spacecraft, which explored Kuiper Belt object Ultima Thule earlier this week, is yielding scientific discoveries daily. Among the findings made by the mission science team in the past day are:

• Initial data analysis has found no evidence of rings or satellites larger than one mile in diameter orbiting Ultima Thule.

• Data analysis has also not yet found any evidence of an atmosphere. • The color of Ultima Thule matches the color of similar worlds in the Kuiper Belt, as determined by

telescopic measurements. • The two lobes of Ultima Thule — the first Kuiper Belt contact binary visited — are nearly identical in

color. This matches what we know about binary systems which haven't come into contact with each other, but rather orbit around a shared point of gravity.

"The first exploration of a small Kuiper Belt object and the most distant exploration of any world in history is now history, but almost all of the data analysis lies in the future," said Alan Stern of the Southwest Research Institute in Boulder, Colorado.

The new images — taken from as close as 17,000 miles (27,000 kilometers) on approach — revealed Ultima Thule as a "contact binary," consisting of two connected spheres. End to end, the world measures 19 miles (31 kilometers) in length. The team has dubbed the larger sphere "Ultima" (12 miles/19 kilometers across) and the smaller sphere "Thule" (9 miles/14 kilometers across).

The team says that the two spheres likely joined as early as 99 percent of the way back to the formation of the solar system, colliding no faster than two cars in a fender-bender.

"New Horizons is like a time machine, taking us back to the birth of the solar system. We are seeing a physical representation of the beginning of planetary formation, frozen in time," said Jeff Moore, New Horizons Geology and Geophysics team lead. "Studying Ultima Thule is helping us understand how planets form — both those in our own solar system and those orbiting other stars in our galaxy."

Data transmission from New Horizons will pause for about a week while the spacecraft passes behind the sun as seen from here on Earth. Data transmission resumes Jan. 10, starting a 20-month download of the spacecraft's remaining scientific treasures.

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"Those of us on the science team can't wait to begin to start digging into that treasure trove," said Stern. New Horizons completed the farthest flyby in history when it came within about 2,200 miles (3,500 kilometers) of Ultima Thule at 12:33 a.m. EST on Jan. 1, zooming past the object at more than 32,000 miles (51,000 kilometers) per hour.

The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, designed, built and operates the New Horizons spacecraft, and manages the mission for NASA's Science Mission Directorate. The Southwest Research Institute, based in San Antonio, leads the science team, payload operations and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.

Follow the New Horizons mission on Twitter and use the hashtags #UltimaThule, #UltimaFlyby and #askNewHorizons to join the conversation. Live updates and links to mission information are also available on http://pluto.jhuapl.edu and www.nasa.gov.

Source: NASA (Jan 3) and NASA (Jan 2) Return to Contents

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2. NASA’s OSIRIS-REx Spacecraft Enters Close Orbit Around Bennu, Breaking Record

At 2:43 p.m. EST on December 31, while many on Earth prepared to welcome the New Year, NASA’s OSIRIS-REx spacecraft, 70 million miles (110 million kilometers) away, carried out a single, eight-second burn of its thrusters – and broke a space exploration record. The spacecraft entered into orbit around the asteroid Bennu, and made Bennu the smallest object ever to be orbited by a spacecraft.

“The team continued our long string of successes by executing the orbit-insertion maneuver perfectly,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “With the navigation campaign coming to an end, we are looking forward to the scientific mapping and sample site selection phase of the mission.”

Lauretta, along with his team, spent the last day of 2018 with his feet planted on Earth, but his mind focused on space. “Entering orbit around Bennu is an amazing accomplishment that our team has been planning for years,” Lauretta said.

Inching around the asteroid at a snail’s pace, OSIRIS-REx’s first orbit marks a leap for humankind. Never before has a spacecraft from Earth circled so close to such a small space object – one with barely enough gravity to keep a vehicle in a stable orbit.

Now, the spacecraft will circle Bennu about a mile (1.75 kilometers) from its center, closer than any other spacecraft has come to its celestial object of study. (Previously the closest orbit of a planetary body was in May 2016, when the Rosetta spacecraft orbited about four miles (seven kilometers) from the center of the comet 67P/Churyumov-Gerasimenko.) The comfortable distance is necessary to keep the spacecraft locked to Bennu, which has a gravity force only 5-millionths as strong as Earth’s. The spacecraft is scheduled to orbit Bennu through mid-February at a leisurely 62 hours per orbit.

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Now that the OSIRIS-REx spacecraft is closer to Bennu, physical details about the asteroid will leap into sharper focus, and the spacecraft’s tour of this rubble pile of primordial debris will become increasingly detailed and focused.

“Our orbit design is highly dependent on Bennu’s physical properties, such as its mass and gravity field, which we didn’t know before we arrived,” said OSIRIS-REx’s flight dynamics system manager Mike Moreau, who is based at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

“Up until now, we had to account for a wide variety of possible scenarios in our computer simulations to make sure we could safely navigate the spacecraft so close to Bennu. As the team learned more about the asteroid, we incorporated new information to hone in on the final orbit design,” he said.

The simulations have played a critical role. The OSIRIS-REx mission, after all, was designed based on complex computer programs that predicted — quite accurately, as it turns out — the properties of Bennu and how the spacecraft’s trajectory would behave. This diligent preparation allowed the team to navigate the vehicle safely to Bennu in December and put some questions to rest (there are, indeed, signs of ancient water preserved in Bennu’s rocks) and to fly over its poles and equator in a preliminary survey that led to some surprises (Bennu has many large boulders).

Having completed the preliminary survey of Bennu with a flyby of its south pole on December 16, the spacecraft moved to a safe 31 miles (50 kilometers) away from the asteroid to give the navigation team a chance to regroup and prepare for orbit insertion. Next, Lockheed Martin engineers programmed the spacecraft to begin moving back to a position about nine miles (15 kilometers) over Bennu’s north pole to prepare for three burns of its thrusters over the course of 10 days that would place the spacecraft into orbit.

Even though OSIRIS-REx is in the most stable orbit possible, Bennu’s gravitational pull is so tenuous that keeping the spacecraft safe will require occasional adjustments, said Dan Wibben, OSIRIS-REx maneuver and trajectory design lead at KinetX Aerospace in Simi Valley, California.

“The gravity of Bennu is so small, forces like solar radiation and thermal pressure from Bennu’s surface become much more relevant and can push the spacecraft around in its orbit much more than if it were orbiting around Earth or Mars, where gravity is by far the most dominant force,” he said.

The OSIRIS-REx navigation team will use “trim” maneuvers to slightly thrust the spacecraft in one direction or another to correct its orbit and counter these small forces. If the spacecraft drifts away from Bennu, or some other problem forces it into safe mode, it has been programmed to fly away from the asteroid to stay safe from impact.

“It’s simple logic: always burn toward the Sun if something goes wrong,” said Coralie Adam, OSIRIS-REx lead optical navigation engineer at KinetX. Engineers can navigate the spacecraft back into orbit if it drifts away, Adam said, though that’s unlikely to happen.

The navigation and spacecraft operations teams are focused on the first orbital phase. Their primary goal is to transition away from star-based navigation, which allowed the team to locate the spacecraft based on pictures of the star formations around it taken by the cameras onboard. Navigators use methods like this since there is no GPS in deep space and we can’t see the spacecraft from Earth-based telescopes. From this point forward, though, the OSIRIS-REx team will rely on landmarks on Bennu’s surface to track OSIRIS-REx, a more precise technique that will ultimately guide them to a sample-collection site clear of boulders and large rocks, said Adam.

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“After conducting a global imaging and mapping campaign during our recent preliminary survey phase, the science team has created 3-D models of Bennu’s terrain that we’re going to begin using for navigation around the asteroid,” she said.

Another critical objective of this orbital phase, Adam said, is to get a better handle on Bennu’s mass and gravity, features that will influence the planning of the rest of the mission, notably the short touchdown on the surface for sample collection in 2020. In the case of Bennu, scientists can only measure these features by getting OSIRIS-REx very close to the surface to see how its trajectory bends from Bennu’s gravitational pull.

“The Orbital A phase will help improve our detailed models for Bennu’s gravity field, thermal properties, orientation, and spin rate,” said Wibben. “This, in turn, will allow us to refine our trajectory designs for the even more challenging flight activities we will perform in 2019.”

The December 31 maneuver to place the spacecraft into orbit about Bennu is the first of many exciting navigation activities planned for the mission. The OSIRIS-REx team will resume science operations in late February. At that point, the spacecraft will perform a series of close flybys of Bennu for several months to take high-resolution images of every square inch of the asteroid to help select a sampling site. During the summer of 2020, the spacecraft will briefly touch the surface of Bennu to retrieve a sample. The OSIRIS-REx mission is scheduled to deliver the sample to Earth in September 2023.

Goddard provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. Dante Lauretta of the University of Arizona, Tucson, is the principal investigator, and the University of Arizona also leads the science team and the mission’s science observation planning and data processing. Lockheed Martin Space in Denver built the spacecraft and is providing flight operations. Goddard and KinetX Aerospace are responsible for navigating the OSIRIS-REx spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program, which is managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama for the agency’s Science Mission Directorate in Washington.

Source: OSIRIX-REx Mission Page Return to Contents

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3. Dark Matter on the Move

Scientists have found evidence that dark matter can be heated up and moved around, as a result of star formation in galaxies. The findings provide the first observational evidence for the effect known as 'dark matter heating', and give new clues as to what makes up dark matter. The research is published today in the journal Monthly Notices of the Royal Astronomical Society.

In the new work, scientists from the University of Surrey, Carnegie Mellon University and ETH Zürich set out to hunt for evidence for dark matter at the centres of nearby dwarf galaxies. Dwarf galaxies are small, faint galaxies that are typically found orbiting larger galaxies like our own Milky Way. They may hold clues that could help us to better understand the nature of dark matter.

Dark matter is thought to make up most of the mass of the universe. However since it doesn't interact with light in the same way as normal matter, it can only be observed through its gravitational effects. The key to studying it may however lie in how stars are formed in these galaxies.

When stars form, strong winds can push gas and dust away from the heart of the galaxy. As a result, the galaxy's centre has less mass, which affects how much gravity is felt by the remaining dark matter. With less gravitational attraction, the dark matter gains energy and migrates away from the centre, an effect called 'dark matter heating'.

The team of astrophysicists measured the amount of dark matter at the centres of 16 dwarf galaxies with very different star formation histories. They found that galaxies that stopped forming stars long ago had higher dark matter densities at their centres than those that are still forming stars today. This supports the theory that the older galaxies had less dark matter heating.

Professor Justin Read, lead author of the study and Head of the Department of Physics at the University of Surrey, said: "We found a truly remarkable relationship between the amount of dark matter at the centres of

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these tiny dwarfs, and the amount of star formation they have experienced over their lives. The dark matter at the centres of the star-forming dwarfs appears to have been 'heated up' and pushed out."

The findings provide a new constraint on dark matter models: dark matter must be able to form dwarf galaxies that exhibit a range of central densities, and those densities must relate to the amount of star formation.

Professor Matthew Walker, a co-author from Carnegie Mellon University, added: "This study may be the "smoking gun" evidence that takes us a step closer to understanding what dark matter is. Our finding that it can be heated up and moved around helps to motivate searches for a dark matter particle."

The team hope to expand on this work by measuring the central dark matter density in a larger sample of dwarfs, pushing to even fainter galaxies, and testing a wider range of dark matter models.

Explore further: Astronomers find that dark matter dominates across cosmic time

More information: J I Read et al, Dark matter heats up in dwarf galaxies, Monthly Notices of the Royal Astronomical Society (2018). DOI: 10.1093/mnras/sty3404

Journal reference: Monthly Notices of the Royal Astronomical Society

Source: Phys.org Return to Contents

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The Night Sky Friday, January 4

• Here is is January, and the Summer Triangle is still in view — if you look early after dark. Vega is its brightest star, low in the northwest. The brightest star above that, and perhaps a bit left, is Deneb. Look for Altair farther to Vega's left and perhaps lower (depending on your latitude).

• In the late-arriving dawns of early January, watch Venus close in on Jupiter and Antares from morning to morning, as shown here.

Saturday, January 5

• As we enter the very coldest time of the year, the dim Little Dipper (Ursa Minor) turns to hang straight down from Polaris after dinnertime — as if, per Leslie Peltier, from a nail on the cold north wall of the sky.

The Big Dipper, meanwhile, is creeping up low in the north-northeast. Its handle is very low and its bowl is to the upper right.

And Cassiopeia, a flattened letter M, is nearly overhead in the north-northwest, just beginning to tilt.

• New Moon (exact at 8:28 p.m. EST).

Sunday, January 6

• Orion stands in the east-southeast after dark, higher every week, but in early evening his three-star Belt is still nearly vertical. The Belt points up toward Aldebaran and, even higher, the Pleiades.

Down below, the Belt points to the horizon where Sirius rises around 6 or 7 p.m. (depending on how far east or west you live in your time zone). Just after Sirius clears the horizon, it twinkles slowly and deeply through thick layers of low atmosphere. It twinkles faster and more shallowly as it gains altitude, and its flashes of vivid color blend into shimmering whiteness.

• Venus is at greatest elongation on this date, 47° west of the Sun in the morning sky.

Monday, January 7

• You may know where the center of our Milky Way galaxy is: in Sagittarius next to the Large Sagittarius Star Cloud. But that's for summer. I bet you've never located the galactic anticenter in the winter sky! Pinpoint its location near Elnath, at the Taurus-Auriga border, using binoculars and Matt Wedel's diamond-shaped asterism in his Binocular Highlight column in the January Sky & Telescope, page 43. Here, you're looking precisely away from the galaxy's center.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver:

Date Visible Max Height Appears Disappears Sat Jan 5, 5:57 AM 2 min 12° 11° above N 10° above NE Sun Jan 6, 6:41 AM 4 min 24° 11° above NNW 15° above ENE Mon Jan 7, 5:50 AM 3 min 17° 15° above N 10° above ENE Tue Jan 8, 5:00 AM < 1 min 11° 11° above NE 10° above NE Tue Jan 8, 6:33 AM 4 min 46° 10° above NW 35° above E

Sighting information for other cities can be found at NASA’s Satellite Sighting Information NASA-TV Highlights (all times Eastern Daylight Time) No special programming listed

Watch NASA TV on the Net by going to the NASA website. Return to Contents

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Space Calendar • Jan 04 - Comet 175P/Hergenrother Closest Approach To Earth (1.840 AU) • Jan 04 - Apollo Asteroid 2014 AD16 Near-Earth Flyby (0.033 AU) • Jan 04 - [Jan 03] Apollo Asteroid 2018 YP2 Near-Earth Flyby (0.036 AU) • Jan 04 - Apollo Asteroid 2004 XP14 Near-Earth Flyby (0.073 AU) • Jan 04 - Asteroid 55555 DNA Closest Approach To Earth (1.833 AU) • Jan 04 - Asteroid 671 Carnegia Closest Approach To Earth (1.921 AU) • Jan 04 - 15th Anniversary (2004), Mars Exploration Rover A (Spirit), Mars Landing

• Jan 05 - [Dec 29] 50th Anniversary (1969), Venera 5 Launch (USSR Venus Atmospheric Probe) • Jan 05 - Comet 357P/Hill At Opposition (1.974 AU) • Jan 05 - Comet 31P/Schwassmann-Wachmann Closest Approach To Earth (2.521 AU) • Jan 05 - Asteroid 3 Juno Occults UCAC5 442-004580 (11.5 Magnitude Star) • Jan 05 - [Jan 03] Apollo Asteroid 2018 YR2 Near-Earth Flyby (0.023 AU) • Jan 05 - Asteroid 19204 Joshuatree Closest Approach To Earth (1.836 AU) • Jan 05 - Asteroid 15550 Sydney Closest Approach To Earth (2.188 AU) • Jan 05 - Workshop: The Science of Harry Potter, San Diego, California

• Jan 06 - [Dec 30] Partial Solar Eclipse (Visible in Eastern Asia & Northern Pacific Ocean) • Jan 06 - [Dec 29] KH-11 17 (Crystal 17, NROL-71) Delta 4H Launch • Jan 06 - Venus At Its Greatest Western Elongation (47 Degrees) • Jan 06 - Apollo Asteroid 2018 XO4 Near-Earth Flyby (0.020 AU) • Jan 06 - Asteroid 19482 Harperlee Closest Approach To Earth (2.734 AU) • Jan 07 - Iridium Next 66-75 Falcon 9 Launch • Jan 07 - Comet C/2018 X2 (Fitzsimmons) Closest Approach To Earth (2.228 AU) • Jan 07 - Comet C/2016 N6 (PANSTARRS) At Opposition (2.414 AU) • Jan 07 - Comet 236P/LINEAR Closest Approach To Earth (2.675 AU) • Jan 07 - Comet 139P/Vaisala-Oterma Closest Approach To Earth (2.852 AU) • Jan 07 - Comet C/2017 U5 (PANSTARRS) Closest Approach To Earth (4.164 AU) • Jan 07 - Asteroid 433 Eros Occults TYC 3329-2004-1 (10.4 Magnitude Star) • Jan 07 - Apollo Asteroid 2016 AZ8 Near-Earth Flyby (0.030 AU) • Jan 07 - Apollo Asteroid 2017 MZ Near-Earth Flyby (0.096 AU) • Jan 07 - Asteroid 3594 Scotti Closest Approach To Earth (1.528 AU)

Mars Exploration Rover (MER) Spirit Mission Badge

Source: JPL Space Calendar Return to Contents

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Food for Thought

Quadrantid Meteors Kickoff a Busy January 2019

Happy New Year! The beginning of the first month of the year is always a busy one for astronomy, and January 2019 is no different, as the Earth reaches perihelion, the Quadrantid meteors peak, and a partial solar eclipse crosses the Pacific… all this week.

Earth at Perihelion

First up, the Earth reaches perihelion on January 3rd at 5:20 Universal Time (UT) January 2nd, 11:20 PM Eastern Standard Time (EST). Though it may not feel it for residents of the chilly northern hemisphere, we’re actually slightly closer to the Sun in early January. In 2019, perihelion reaches 149.8 million kilometers (92.957 million miles) from the Sun, versus aphelion at 152.1 million kilometers (94.5 million miles) on July 4th, 2019. In the 21st century, perihelion can range from 0.9832436 AU (2020) to 0.9833866 AU (2098). Fun fact: the Sun actually appears a smidgen tinier as seen from Earth in January versus July (31′ versus 33′ arcminutes) an effect you can actually photograph.

The Sun at perihelion versus aphelion. Credit: Dave Dickinson

The date of perihelion and aphelion is also slowly changing, along with the precession of the equinoxes, eccentricity of the Earth’s orbit and the obliquity of the rotational poles in something known as Milankovitch Cycles. In the 21st century, perihelion can occur anywhere from January 2nd to January 5th, largely thanks to the Julian Calendar’s cycle of adding leap days every four years, and aphelion can occur anywhere from July 3rd to 7th.

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The Quadrantid Meteors

Next up, the elusive Quadrantid meteors peak on the night of January 3nd into the morning of January 4th, 2019. The “Quads” are often a tough catch; the meteor shower has a sharp but swift six hour peak, often favoring one select longitude, leaving the rest of the world in the dark. In 2019, the peak Zenithal Hourly Rate (ZHR) of 120 meteors per hour is set to occur on January 4th at 2:00 UT, favoring Europe. The Quadrantids favor northern hemisphere observers, and the radiant is located near a point where the constellations of Hercules, Ursa Major and Bootes meet.

Quadrans Muralis, resurrected. Credit: Dave Dickinson

The Quadrantids take their name from the now defunct constellation of Quadrans Muralis, the Mural Quadrant. The source of the Quadrantid meteors is the asteroid 2003 EH. 2019 is an especially auspicious year for the Quads, as the Moon is just a 5 percent illuminated, waning crescent at the shower’s peak, offering very little by the way of light pollution. The Quads seem to be a dynamically new shower. You just never know: It’s always worth watching for the Quadrantid meteors around the beginning of the year.

A Pacific-Spanning Partial Solar Eclipse

Finally, this weekend’s New Moon also features the start of the first eclipse season for 2019, with a partial solar eclipse spanning the northern Pacific and the International Date Line on January 5-6th.

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The January 5-6 partial solar eclipse. Credit: Michael Zieler.

New Moon and mid-eclipse occurs on January 6th at 1:30 UT, and Japan, the Koreas and China will get a maximum totality of 1 to 45 percent, south to north. Remote easternmost Russia will get the very best view, at plus 60 percent obscuration. Sparsely populated southwestern Alaska may also get an interesting view if skies are clear of a half-eclipsed Sun at sunset. This eclipse season is also book-ended with a fine total lunar eclipse for North/South America and western Europe on the night of January 21st.

All three astro-events make an amazing trio to kick off 2019.

Source: Universe Today Return to Contents

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Space Image of the Week

The Sombrero Galaxy in Infrared Explanation This floating ring is the size of a galaxy. In fact, it is a galaxy -- or at least part of one: the photogenic Sombrero Galaxy, one of the largest galaxies in the nearby Virgo Cluster of Galaxies. The dark band of dust that obscures the mid-section of the Sombrero Galaxy in optical light actually glows brightly in infrared light. The featured image, digitally sharpened, shows the infrared glow, recently recorded by the orbitingSpitzer Space Telescope, superposed in false-color on an existing image taken by NASA's Hubble Space Telescope in optical light. The Sombrero Galaxy, also known as M104, spans about 50,000 light years across and lies 28 million light years away. M104 can be seen with a small telescope in the direction of the constellation Virgo. Image Credit: R. Kennicutt (Steward Obs.) et al., SSC, JPL, Caltech, NASA Source: APOD Return to Contents