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Space News Update — April 12, 2019 —

Contents

In the News

Story 1: Black Hole Image Makes History; NASA Telescopes Coordinated Observations

Story 2:

Curiosity Tastes First Sample in 'Clay-Bearing Unit'

Story 3: Pinpointing the Origin of Photons in Mysterious Gamma-ray Bursts

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. Black Hole Image Makes History; NASA Telescopes Coordinated Observations

A black hole and its shadow have been captured in an image for the first time, a historic feat by an international network of radio telescopes called the Event Horizon Telescope (EHT). EHT is an international collaboration whose support in the U.S. includes the National Science Foundation.

A black hole is an extremely dense object from which no light can escape. Anything that comes within a black hole’s “event horizon,” its point of no return, will be consumed, never to re-emerge, because of the black hole’s unimaginably strong gravity. By its very nature, a black hole cannot be seen, but the hot disk of material that encircles it shines bright. Against a bright backdrop, such as this disk, a black hole appears to cast a shadow.

The stunning new image shows the shadow of the supermassive black hole in the center of Messier 87 (M87), an elliptical galaxy some 55 million light-years from Earth. This black hole is 6.5 billion times the mass of the Sun. Catching its shadow involved eight ground-based radio telescopes around the globe, operating together as if they were one telescope the size of our entire planet.

“This is an amazing accomplishment by the EHT team,” said Paul Hertz, director of the astrophysics division at NASA Headquarters in Washington. “Years ago, we thought we would have to build a very large space telescope to image a black hole. By getting radio telescopes around the world to work in concert like one instrument, the EHT team achieved this, decades ahead of time.”

To complement the EHT findings, several NASA spacecraft were part of a large effort, coordinated by the EHT’s Multiwavelength Working Group, to observe the black hole using different wavelengths of light. As part of this effort, NASA’s Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift Observatory space telescope missions, all attuned to different varieties of X-ray light, turned their gaze to the M87 black hole around the same time as the EHT in April 2017. NASA’s Fermi Gamma-ray Space Telescope was also watching for changes in gamma-ray light from M87 during the EHT observations. If

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EHT observed changes in the structure of the black hole’s environment, data from these missions and other telescopes could be used to help figure out what was going on.

Chandra X-ray Observatory close-up of the core of the M87 galaxy. Credits: NASA/ CXC/ Villanova University/ J. Neilsen

While NASA observations did not directly trace out the historic image, astronomers used data from NASA’s Chandra and NuSTAR satellites to measure the X-ray brightness of M87’s jet. Scientists used this information to compare their models of the jet and disk around the black hole with the EHT observations. Other insights may come as researchers continue to pore over these data.

There are many remaining questions about black holes that the coordinated NASA observations may help answer. Mysteries linger about why particles get such a huge energy boost around black holes, forming dramatic jets that surge away from the poles of black holes at nearly the speed of light. When material falls into the black hole, where does the energy go?

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“X-rays help us connect what’s happening to the particles near the event horizon with what we can measure with our telescopes,” said Joey Neilsen, an astronomer at Villanova University in Pennsylvania, who led the Chandra and NuSTAR analysis on behalf of the EHT’s Multiwavelength Working Group.

Chandra X-ray Observatory close-up of the core of the M87 galaxy. Credits: NASA/ CXC/ Villanova University/ J. Neilsen

NASA space telescopes have previously studied a jet extending more than 1,000 light-years away from the center of M87. The jet is made of particles traveling near the speed of light, shooting out at high energies from close to the event horizon. The EHT was designed in part to study the origin of this jet and others like it. A blob of matter in the jet called HST-1, discovered by Hubble astronomers in 1999, has undergone a mysterious cycle of brightening and dimming.

Chandra, NuSTAR, Swift and Fermi, as well as NASA’s Neutron star Interior Composition Explorer (NICER) experiment on the International Space Station, also looked at the black hole at the center of our own Milky Way galaxy, called Sagittarius A*, in coordination with EHT.

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Getting so many different telescopes on the ground and in space to all look toward the same celestial object is a huge undertaking in and of itself, scientists emphasize.

“Scheduling all of these coordinated observations was a really hard problem for both the EHT and the Chandra and NuSTAR mission planners,” Neilsen said. “They did really incredible work to get us the data that we have, and we’re exceedingly grateful.”

Neilsen and colleagues who were part of the coordinated observations will be working on dissecting the entire spectrum of light coming from the M87 black hole, all the way from low-energy radio waves to high-energy gamma rays. With so much data from EHT and other telescopes, scientists may have years of discoveries ahead.

Source: NASA Return to Contents

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2. Curiosity Tastes First Sample in 'Clay-Bearing Unit'

Scientists working with NASA's Curiosity Mars rover have been excited to explore a region called "the clay-bearing unit" since before the spacecraft launched. Now, the rover has finally tasted its first sample from this part of Mount Sharp. Curiosity drilled a piece of bedrock nicknamed "Aberlady" on Saturday, April 6 (the 2,370th Martian day, or sol, of the mission), and delivered the sample to its internal mineralogy lab on Wednesday, April 10 (Sol 2374).

The rover's drill chewed easily through the rock, unlike some of the tougher targets it faced nearby on Vera Rubin Ridge. It was so soft, in fact, that the drill didn't need to use its percussive technique, which is helpful for snagging samples from harder rock. This was the mission's first sample obtained using only rotation of the drill bit.

"Curiosity has been on the road for nearly seven years," said Curiosity Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory in Pasadena, California. "Finally drilling at the clay-bearing unit is a major milestone in our journey up Mount Sharp."

Scientists are eager to analyze the sample for traces of clay minerals because they usually form in water. NASA's Mars Reconnaissance Orbiter (MRO) spied a strong clay "signal" here long before Curiosity landed in 2012. Pinpointing the source of that signal could help the science team understand if a wetter Martian era shaped this layer of Mount Sharp, the 3-mile-tall (5-kilometer-tall) mountain Curiosity has been climbing.

Curiosity has discovered clay minerals in mudstones all along its journey. These mudstones formed as river sediment settled within ancient lakes nearly 3.5 billion years ago. As with water elsewhere on Mars, the lakes eventually dried up.

The clay beacon seen from space brought the rover here, but the region clearly has several other stories to tell. Now that Curiosity is searching this area, scientists can peer around as geological tourists, finding a

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landscape both ancient and new. There are several kinds of bedrock and sand, including active sand ripples that have shifted in the past year. Pebbles are scattered everywhere - are they eroding from the local bedrock? Several eye-catching landmarks, such as "Knockfarril Hill," stick out as well.

"Each layer of this mountain is a puzzle piece," said Curiosity Project Scientist Ashwin Vasavada of JPL. "They each hold clues to a different era in Martian history. We're excited to see what this first sample tells us about the ancient environment, especially about water."

The Aberlady sample will give the team a starting point for thinking about the clay-bearing unit. They plan to drill several more times over the course of the next year. That will help them understand what makes this region different from the ridge behind it and an area with a sulfate signal up higher on the mountain.

Source: Phys.org Return to Contents

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3. Pinpointing the Origin of Photons in Mysterious Gamma-ray Bursts

Scientists from the RIKEN Cluster for Pioneering Research and collaborators have used simulations to show that the photons emitted by long gamma-ray bursts--one of the most energetic events to take place in the universe--originate in the photosphere--the visible portion of the "relativistic jet" that is emitted by exploding stars.

Gamma-ray bursts are the most powerful electromagnetic phenomenon observed in the universe, releasing as much energy in just a second or so as the sun will release over its entire lifetime. Though they were discovered in 1967, the mechanism behind this enormous release of energy long remained mysterious. Decades of studies finally revealed that long bursts--one of the types of bursts--originate from relativistic jets of matter ejected during the death of massive stars. However, exactly how the gamma-rays are produced from the jets is still veiled in mystery today.

The current research, published in Nature Communications, began from a discovery called the Yonetoku relation, which was originally made by one of the authors of the paper. This relation between the spectral peak energy and peak luminosity of GRBs is the tightest correlation found so far in the properties of GRB emission. It thus provides the best diagnostic so far for explaining the emission mechanism, and the strictest test for any model of gamma-ray bursts. Incidentally, the relationship also meant that long gamma-ray bursts could be used as a "standard candle" for measuring distance, allowing us to peer further into the past than type 1A supernovae, which are commonly used today but are much dimmer than the bursts. This would make

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it possible to gain insights into the history of the universe, and could give us insights into mysteries such as dark matter and dark energy.

Using computer simulations performed on several supercomputers, including Aterui of the National Astronomical Observatory of Japan, Hokusai of RIKEN, and Cray xc40 of the Yukawa Institute for Theoretical Physics, the group focused on the so-called "photospheric emission" model, one of the leading models for the emission mechanism of GRBs. This model postulates that the photons visible on earth are emitted from the photosphere of the relativistic jet. As the jet expands, it becomes easier for photons to escape from within it, since there are fewer objects available to scatter the light. Thus, the "critical density" --the place where it becomes possible for the photons to escape-- moves downward through the jet, to material that was originally at higher and higher densities.

To test the validity of the model, the team set out to test it in a way that took into account the global dynamics of relativistic jets and radiation transfer. By using a combination of three-dimensional relativistic hydrodynamical simulations and radiation transfer calculations to evaluate photospheric emissions from a relativistic jet breaking out of massive star envelope, they were able to determine that at least in the case of long GRBs--the type associated with such collapsing massive stars--the model worked. Their simulations revealed that the Yonetoku relation could be reproduced as a natural consequence of the jet-stellar interactions. "To us," says Hirotaka Ito of the Cluster for Pioneering Research, "this strongly suggests that photospheric emission is the emission mechanism of GRBs."

He continues, "While we have elucidated the origin of the photons, there are still mysteries concerning how the relativistic jets themselves are generated by the collapsing stars. Our calculations should provide valuable insights for looking into the fundamental mechanism behind the generation of these tremendously powerful events."

Source: Spaceref.com Return to Contents

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The Night Sky Friday, April 12

• First-quarter Moon (exactly so at 3:06 p.m. EDT). Early this evening, the Moon shines high in the southwest with Pollux and Castor to its upper right and brighter Procyon lower left of it, as shown here.

Saturday, April 13

• At this time of year, the two Dog Stars stand vertically aligned around the end of twilight. Look southwest. Far under the Moon this evening is Procyon in Canis Minor. Brilliant Sirius, in Canis Major, is a similar distance below Procyon.

Later in the evening the arrangement moves lower and rotates a bit clockwise, as seen here. The Dog Stars are following Orion down toward making their seasonal exits in the southwest.

• Use binoculars tonight to look for M44, the scattery Beehive Star Cluster in Cancer, roughly 3° to the right of the glary Moon (as seen from the longitudes of North America).

Sunday, April 14

• The gibbous Moon shines upper right of Regulus this evening.

• The huge, bright Winter Hexagon still fills the sky to the southwest and west at the end of twilight. Start with brilliant Sirius in the southwest, the Hexagon's lower left corner. High above Sirius is Procyon. From there look even higher for Pollux and Castor, rightward from Castor to Menkalinan and bright Capella, lower left from there to Aldebaran, lower left to Rigel way down at the bottom of Orion, and back to Sirius.

Monday, April 15

• Arcturus shines brightly in the east these evenings. The Big Dipper, very high in the northeast, points its curving handle lower-right toward it.

Arcturus forms the pointy end of a long, narrow kite asterism formed by the brightest stars of Bootes, the Cowherd. The kite is currently lying on its side to Arcturus's left. The head of the kite, at the far left, is bent slightly upward. The kite is 23° long, about two fists at arm's length.

Source: Sky & Telescope Return to Contents

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ISS Sighting Opportunities

For Denver: No Sighting Opportunities 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

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

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Space Calendar

• Apr 12 - [Apr 05] International Day of Human Space Flight

• Apr 12 - [Apr 05] Yuri's Night: World Space Party • Apr 12 - Comet P/2015 X1 (PANSTARRS) At Opposition (4.160 AU) • Apr 12 - [Apr 10] Apollo Asteroid 2019 GC4 Near-Earth Flyby (0.013 AU) • Apr 12 - [Apr 05] Apollo Asteroid 2019 FB3 Near-Earth Flyby (0.030 AU) • Apr 12 - [Apr 06] Apollo Asteroid 2019 GQ1 Near-Earth Flyby (0.034 AU) • Apr 12 - [Apr 10] Apollo Asteroid 2019 GL4 Near-Earth Flyby (0.037 AU) • Apr 12 - Asteroid 295565 Hannover Closest Approach To Earth (1.953 AU) • Apr 12 - Asteroid 23469 Neilpeart Closest Approach To Earth (2.185 AU) • Apr 12 - Amor Asteroid 162011 Konnohmaru Closest Approach To Earth (3.099 AU) • Apr 12 - 170th Anniversary (1849), Annibale de Gasparis' Discovery of Asteroid 10 Hygiea • Apr 13 - Comet C/2014 C1 (TOTAS) Perihelion (1.684 AU) • Apr 13 - Comet 103P/Hartley At Opposition (4.239 AU) • Apr 13 - [Apr 06] Apollo Asteroid 2019 GN Near-Earth Flyby (0.004 AU) • Apr 13 - [Apr 10] Apollo Asteroid 2019 GO4 Near-Earth Flyby (0.013 AU) • Apr 13 - [Apr 10] Apollo Asteroid 2019 GN4 Near-Earth Flyby (0.019 AU) • Apr 13 - Apollo Asteroid 2019 FO1 Near-Earth Flyby (0.037 AU) • Apr 13 - Amor Asteroid 2019 FH1 Near-Earth Flyby (0.046 AU) • Apr 13 - Asteroid 6000 United Nations Closest Approach To Earth (2.084 AU) • Apr 13-16 - American Physical Society (APS) Meeting, Denver, Colorado • Apr 14 - Apollo Asteroid 2016 FW13 Near-Earth Flyby (0.073 AU) • Apr 14 - Asteroid 11998 Fermilab Closest Approach To Earth (2.612 AU) • Apr 14 - Asteroid 7359 Messier Closest Approach To Earth (2.623 AU) • Apr 14 - Christiaan Huygens' 390th Birthday (1629) • Apr 15 - Comet 49P/Arend-Rigaux At Opposition (2.014 AU) • Apr 15 - Comet C/2018 F4 (PANSTARRS) At Opposition (3.316 AU) • Apr 15 - Comet 61P/Shajn-Schaldach At Opposition (4.245 AU) • Apr 15 - Comet C/2017 F2 (PANSTARRS) Closest Approach To Earth (6.675 AU) • Apr 15 - Asteroid 8861 Jenskandler Occults HIP 81724 (4.5 Magnitude Star) • Apr 15 - Asteroid 215423 Winnecke Closest Approach To Earth (1.371 AU) • Apr 15 - Asteroid 4149 Harrison Closest Approach To Earth (1.387 AU) • Apr 15 - Asteroid 30857 Parsec Closest Approach To Earth (1.435 AU) • Apr 15 - Asteroid 46977 Krakow Closest Approach To Earth (2.050 AU) • Apr 15 - Johannes Stark's 145th Birthday (1874)

Christiaan Huygens

Source: JPL Space Calendar Return to Contents

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Food for Thought

NASA’s Landmark Twins Study Reveals Resilience of Human Body in Space

Results from NASA’s landmark Twins Study, which took place from 2015-2016, were published Thursday in Science. The integrated paper — encompassing work from 10 research teams — reveals some interesting, surprising and reassuring data about how one human body adapted to — and recovered from — the extreme environment of space.

The Twins Study provides the first integrated biomolecular view into how the human body responds to the spaceflight environment, and serves as a genomic stepping stone to better understand how to maintain crew health during human expeditions to the Moon and Mars.

Retired NASA astronauts Scott Kelly and his identical twin brother Mark, participated in the investigation, conducted by NASA’s Human Research Program. Mark provided a baseline for observation on Earth, and Scott provided a

comparable test case during the 340 days he spent in space aboard the International Space Station for Expeditions 43, 44, 45 and 46. Scott Kelly became the first American astronaut to spend nearly a year in space.

“The Twins Study has been an important step toward understanding epigenetics and gene expression in human spaceflight,” said J.D. Polk, chief Health and Medical Officer at NASA Headquarters. “Thanks to the twin brothers and a cadre of investigators who worked tirelessly together, the valuable data gathered from the Twins Study has helped inform the need for personalized medicine and its role in keeping astronauts healthy during deep space exploration, as NASA goes forward to the Moon and journeys onward to Mars.”

Key results from the NASA Twins Study include findings related to gene expression changes, immune system response, and telomere dynamics. Other changes noted in the integrated paper include broken chromosomes rearranging themselves in chromosomal inversions, and a change in cognitive function. Many of the findings are consistent with data collected in previous studies, and other research in progress.

The telomeres in Scott’s white blood cells, which are biomarkers of aging at the end of chromosomes, were unexpectedly longer in space then shorter after his return to Earth with average telomere length returning to normal six months later. In contrast, his brother’s telomeres remained stable throughout the entire period. Because telomeres are important for cellular genomic stability, additional studies on telomere dynamics are planned for future one-year missions to see whether results are repeatable for long-duration missions.

A second key finding is that Scott’s immune system responded appropriately in space. For example, the flu vaccine administered in space worked exactly as it does on Earth. A fully functioning immune system during long-duration space missions is critical to protecting astronaut health from opportunistic microbes in the spacecraft environment.

A third significant finding is the variability in gene expression, which reflects how a body reacts to its environment and will help inform how gene expression is related to health risks associated with spaceflight.

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While in space, researchers observed changes in the expression of Scott’s genes, with the majority returning to normal after six months on Earth. However, a small percentage of genes related to the immune system and DNA repair did not return to baseline after his return to Earth. Further, the results identified key genes to target for use in monitoring the health of future astronauts and potentially developing personalized countermeasures.

“A number of physiological and cellular changes take place during spaceflight,” said Jennifer Fogarty, chief scientist of the Human Research Program at NASA’s Johnson Space Center in Houston. “We have only scratched the surface of knowledge about the body in space. The Twins Study gave us the first integrated molecular view into genetic changes, and demonstrated how a human body adapts and remains robust and resilient even after spending nearly a year aboard the International Space Station. The data captured from integrated investigations like the NASA Twins Study will be explored for years to come.”

Part of the record-setting one-year mission, the NASA Twins Study incorporated 10 investigations to advance NASA’s mission and benefit all of humanity. Scott participated in a number of biomedical studies, including research into how the human body adjusts to known hazards, such as weightlessness and space radiation. Meanwhile, Mark participated in parallel studies on Earth to help scientists compare the effects of space on a body down to the cellular level. The findings represent 27 months of data collection.

The Twins Study helped establish a framework of collaborative research that serves as a model for future biomedical research. Principal investigators at NASA and at research universities across the nation initiated an unprecedented sharing of data and discovery. Supported by 84 researchers at 12 locations across eight states, the data from this complex study was channeled into one inclusive study, providing the most comprehensive and integrated molecular view to date of how a human responds to the spaceflight environment. While significant, it is difficult to draw conclusions for all humans or future astronauts from a single test subject in the spaceflight environment.

“To our knowledge, this team of teams has conducted a study unprecedented in its scope across levels of human biology: from molecular analyses of human cells and the microbiome to human physiology to cognition,” said Craig Kundrot, director, Space Life and Physical Sciences Research and Application Division at NASA Headquarters. “This paper is the first report of this highly integrated study that began five years ago when the investigators first gathered. We look forward to the publication of additional analyses and follow-up studies with future crew members as we continue to improve our ability to live and work in space and venture forward to the Moon and on to Mars.”

The unique aspects of the Twins Study created the opportunity for innovative genomics research, propelling NASA into an area of space travel research involving a field of study known as “omics,” which integrates multiple biological disciplines. Long-term effects of research, such as the ongoing telomeres investigation, will continue to be studied.

NASA has a rigorous training process to prepare astronauts for their missions, including a thoroughly planned lifestyle and work regime while in space, and an excellent rehabilitation and reconditioning program when they return to Earth. Thanks to these measures and the astronauts who tenaciously accomplish them, the human body remains robust and resilient even after spending a year in space.

For more information about the NASA Twins Study, visit: https://www.nasa.gov/twins-study.

Source: NASA Return to Contents

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Space Image of the Week

Moon Occults Saturn Explanation Sometimes Saturn disappears. It doesn't really go away, though, it just disappears from view when our Moon moves in front. Such a Saturnian eclipse was visible along a small swath of Earth -- fromBrazil to Sri Lanka -- near the end of last month. The featured color image is a digital fusion of the clearest images captured by successive videos of the event taken in red, green, and blue, and taken separately forSaturn and the comparative bright Moon. The exposures were taken from South Africa just before occultation -- and also just before sunrise. When Saturn re-appeared on the other side of the Moon almost two hours later, the Sun had risen. This year, eclipses of Saturn by the Moon occur almost monthly, but, unfortunately, are visible only to those with the right location and with clear and dark skies. Image Credit & Copyright: Cory Schmitz Source: APOD Return to Contents