Study Suggests Rainfall Triggered 2018 Kīlauea Eruption

NASA & JAXA - Global Precipitation Measurement (GPM) patch.

April 22, 2020

In May 2018 Kīlauea volcano on the island of Hawaii erupted, touching off months of intense activity. Through August, incandescent lava from fissures spewed hundreds of feet in the air, and billowing ash clouds reached as high as six miles into the atmosphere. Huge lava flows inundated land up and down the Pacific island’s southeast coast, destroying hundreds of homes.

Volcanoes erupt when molten rock called magma rises to the surface, and many factors, from the shape of the volcano to the composition of the magma, factor into the timing of eruptions. In the case of Kīlauea, a new, NASA-funded study published April 22 in the journal Nature points to another eruption factor: prolonged, sometimes heavy rainfall in the months leading up to the event.

Image above: The Landsat-9 satellite captured a plume of steam rising above the summit of Kilauea volcano on May 14, 2018. A few weeks prior, on May 3, Kilauea had erupted along its East Rift Zone, initiating months of volcanic activity that would destroy hundreds of homes along the southeastern portion of the island. Image Credits: NASA Earth Observatory images by Joshua Stevens, using Landsat data from the U.S. Geological Survey.

“We knew that changes to water content in Earth’s shallow crust can trigger earthquakes and landslides, and now we know that it can also trigger eruptions,” said Falk Amelung, professor of geophysics at the University of Miami Rosenstiel School of Marine and Atmospheric Science and co-author of the study. “Under pressure from magma, wet rock breaks easier than dry rock inside the volcano. That, in turn, forges pathways for magma to travel to Earth’s surface.”

First, for the 2018 Kīlauea eruption researchers ruled out a common cause: increased pressure in the magma chamber, which, when it becomes great enough, is able to break through the surrounding rock. Scientists can infer increased magma pressure by observing the inflation, or rise, of the surrounding rock. “This pressurization causes the ground to inflate by a few tens of centimeters,” Amelung explained. “As we did not see any significant inflation in the year prior to the eruption, we started to think about alternative explanations, which led us to investigating precipitation.”

Using a combination of ground-based and NASA satellite measurements of rainfall, the researchers modeled the evolution of fluid pressure caused by sustained rainfall that accumulated in the volcano’s interior—a factor that can directly influence the propensity for magma to break through the surrounding rock, ultimately driving volcanic activity. Based on pre-existing laboratory data and numerical simulations, their model results suggest that, in early 2018, fluid pressure had been at its highest in almost half a century, weakening the volcanic edifice, which the authors propose enabled magma to break through confining rock beneath the volcano and lead to the subsequent eruption.

Image above: Overnight, fountains of lava as high as 160 feet had erupted from the fissure 8 vent along the East Rift Zone by the time this photo was taken on the morning of June 12, 2018. Image Credits: USGS Hawaiian Volcano Observatory (HVO).

“Interestingly, when we investigate Kīlauea’s historical eruption record, we see that magmatic intrusions and recorded eruptions are almost twice as likely to occur during the wettest parts of the year,” said Jamie Farquharson, a postdoctoral researcher at the Rosenstiel School and lead author of the study. He argues that local rainfall patterns may contribute significantly to the timing and frequency of these phenomena at Kīlauea and perhaps at other volcanoes.

While rainfall infiltration has been linked to small steam explosions and volcanic earthquakes, this is the first time that scientists attribute months of above-average rainfall to explain magmatic processes more than a mile below the surface. In the case of the Kīlauea eruption, the first quarter’s total rainfall over the volcano that year was about 2.25 meters compared to the 0.9-meter average for the area in that timeframe over the past 20 years. The authors note that if this process occurs as proposed at Kīlauea, then it is likely to occur elsewhere as well.

NASA/JAXA Tropical Rainfall Measurement Mission, GPM

A climatic link may also be at play, Farquharson said, as ongoing climate change is predicted to bring about changes in rainfall patterns. In particular, most models project increases in extreme precipitation over most of the globe, an effect that may be further amplified in mountainous volcanic regions. “As a result, we expect that rainfall-induced volcanic activity could become more common.”

For satellite measurements of rainfall, researchers used data from the Global Precipitation Measurement—an international mission led by NASA and the Japanese Space Exploration Agency (JAXA) — and the earlier NASA/JAXA Tropical Rainfall Measurement Mission. The European Space Agency’s and European Commission’s Sentinel-1 satellite provided researchers with data from which ground deformation observations were derived. NASA’s Earth Science Division provided funding support.

For more NASA Earth science news, visit: https://www.nasa.gov/earth

GPM (Global Precipitation Measurement): http://www.nasa.gov/mission_pages/GPM/main/index.html

Images (mentioned), Text, Credits: NASA/Ellen Gray/Earth Science News Team, by Samson Reiny.

Greetings, Orbiter.ch

Advanced Space Research Ahead of Weekend Cargo Mission

ISS - Expedition 63 Mission patch.

April 21, 2020

Expedition 63 Commander Chris Cassidy of NASA continued working on a variety of science hardware throughout the International Space Station today. His two crewmates worked in the orbiting lab’s Russian segment on their complement of science and maintenance.

Cassidy started Tuesday in the Japanese Kibo laboratory module setting up a small satellite deployer. CubeSats are installed into the device, which is then loaded into Kibo’s airlock. Then the deployer is positioned in the vacuum of space to eject the tiny shoebox-sized satellites into Earth orbit.

Image above: NASA astronaut Chris Cassidy holds a Parmigiana di Melanzane meal packet given to him by European Space Agency (ESA) astronaut Luca Parmitano. Image Credit: NASA.

In the afternoon, Cassidy moved over to the U.S. Destiny laboratory module and swapped computer parts inside the Fluids and Combustion Facility (FCF). The FCF consists of two refrigerator-sized research racks enabling safe observations of the behavior of fluids and flames in microgravity. Scientists use the data to design advanced fuel transfer systems and increase fire safety.

Russian Flight Engineers Anatoly Ivanishin and Ivan Vagner logged their meals today to understand how spaceflight affects a crewmember’s nutrition and metabolism. The duo then worked throughout the day on life support maintenance while continuing to get used to life onboard the station.

Image above: A previous Russian Progress cargo craft is pictured departing the International Space Station after undocking from the Pirs docking compartment. Image Credit: NASA.

Russia’s next cargo craft to resupply the station is completing final processing and assembly at the Baikonur Cosmodrome in Kazakhstan. The Progress 75 (75P) space freighter packed with several tons of food, fuel and supplies is due to launch on Friday at 9:51 p.m. EDT. The 75P will make a two-orbit, three-and-a-half hour trip and automatically dock to the aft port of the Zvezda service module.

Related article:

NASA Television to Air Space Station Cargo Ship Launch, Docking
https://www.nasa.gov/press-release/nasa-television-to-air-space-station-cargo-ship-launch-docking-0

Related links:

Expedition 63: https://www.nasa.gov/mission_pages/station/expeditions/expedition63/index.html

Kibo laboratory module: https://www.nasa.gov/mission_pages/station/structure/elements/japan-kibo-laboratory

U.S. Destiny laboratory module: https://www.nasa.gov/mission_pages/station/structure/elements/us-destiny-laboratory

Fluids: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=351

Combustion: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=317

Nutrition and metabolism: https://www.energia.ru/en/iss/researches/human/21.html

Zvezda service module: https://www.nasa.gov/mission_pages/station/structure/elements/zvezda-service-module.html

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

NASA/Mark Garcia.

Nine Reasons We’re Grateful to Live on Earth

NASA - Goddard Space Flight Center (GSFC) logo.

April 21, 2020

Earth can sometimes feel like the last place you’d want to be. Indeed, a number of explorers have devised inventive ways to move civilization off this planet.

Image above: Expedition 48 Commander Jeff Williams of NASA shared this sunrise panorama taken from his vantage point aboard the International Space Station, writing, "Morning over the Atlantic...this one will hang on my wall." Image Credit: NASA.

It’s no surprise: The promise of a better life in the mysterious beyond can be seductive. But the fact is the more we learn about out there the more we realize how special it is here. The first astronauts to look from space back at Earth, a “pale blue dot, the only home we've ever known,” as scientist Carl Sagan once wrote, saw a beautiful, delicate world that is perfectly suited to the bounty of life it supports.

“When I looked up and saw the Earth coming up on this very stark, beat up lunar horizon, an Earth that was the only color that we could see, a very fragile looking Earth, a very delicate looking Earth, I was immediately almost overcome by the thought that here we came all this way to the Moon, and yet the most significant thing we’re seeing is our own home planet, the Earth,” said William Anders, a crew member on Apollo 8, the first crewed mission to the Moon.  

On this 50th anniversary of Earth Day on April 22, we reflect on nine reasons Earth is the best place to live:

Image above: This mosaic was assembled in 2018 from dozens of images taken by the Mast Camera (Mastcam) on NASA's Curiosity rover. In the image, you're looking uphill at Mount Sharp, which is in the middle of Gale Crater on Mars. The scene has been white-balanced so the colors of the rock materials resemble how they would appear under daytime lighting conditions on Earth. Image Credits: NASA/JPL-Caltech/MSSS.

1. We can take deep, cleansing breaths

Known as the Red Planet because of the rust particles in its soil that give it a reddish hue, Mars has always fascinated the human mind. What would it be like to live on this not-so-distant world, many have wondered? One day, astronauts will find out. But we know already that living there would require some major adjustments. No longer would we be able to take long, deep breaths of nitrogen- and oxygen-rich air while a gentle spring breeze grazes the skin. Without a spacesuit providing essential life support, humans would have to inhale carbon dioxide, a toxic gas we typically exhale as a waste product. On top of that, the thin Martian atmosphere (100 times thinner than Earth’s) and lack of a global magnetic field would leave us vulnerable to harmful radiation that damages cells and DNA; the low gravity (38% of Earth’s) would weaken our bones. Besides the hardships our bodies would endure, it would simply be less fun to live on Mars. Summer trips to the beach? Forget them. On Mars, there’s plenty of sand, but not a single swimming hole, much less a lake or ocean, and the average temperature is around minus 81 degrees Fahrenheit (minus 63 degrees Celsius). Even the hardiest humans would find the Martian climate to be a drag. —Staci Tiedeken, planetary science outreach coordinator, NASA’s Goddard Space Flight Center.

Animation above: This animated gif was made using images from NASA’s Solar Dynamics Observatory, which saw this X-class solar flare on Sept. 6, 2017. X-class flares are the strongest of all rating classes, releasing the energy equivalent of a billion hydrogen bombs. Animation Credits: NASA/GSFC/SDO.

2. There’s solid ground to stand on

Earth has grassy fields, rugged mountains and icy glaciers. But to live on the Sun, we’d have to kiss all solid ground goodbye. The Sun is a giant ball of plasma, or super-heated gas. If you tried to stand on the Sun’s visible surface, called the photosphere, you’d fall right through, about 205,000 miles (330,000 kilometers) until you reached a layer of plasma so compressed, it’s as thick as water. But you wouldn’t float, because you’d be crushed by the pressure there: 4.5 million times stronger than the deepest point in the ocean. Get ready for a quick descent, too. The Sun’s gravity is 28 times stronger than Earth’s. Thus, a 170-pound (77-kilogram) adult on Earth would weigh an extra 4,590 pounds (2,245 kilograms) at the Sun. That would feel like wearing an SUV on your back! If a person managed to hover in the photosphere, though, it might get a little warm. The temperature there is around 10,000 degrees Fahrenheit (5,500 Celsius), about five to 10 times hotter than lava — yet, not nearly the hottest temperature on the Sun. Don’t worry, though, there would be a break of 3,000 degrees Fahrenheit (1,600 degrees Celsius) if you stumbled on a sunspot, which is a “cool” region formed by intense magnetic fields. These conditions would have even the most intrepid adventurers longing for the comforts of home. —Miles Hatfield, science writer, NASA's Goddard Space Flight Center.

The Mysterious Planet

Video above: By studying Venus, scientists could learn a great deal more about exoplanets, as well as the past, present and possible future of our own planet. Video Credits: NASA's Goddard Space Flight Center.

3. The seasons go round and round

Since the beginning of recorded history, people have tracked and celebrated nature’s transition from the desolate days of winter, to the brilliant radiance of spring, to the endless days of summer, and so on. Seasons come from a planet’s tilt on its axis (Earth’s is 23.5 degrees), which tips each hemisphere either toward or away from the heat of the Sun throughout the year. Venus, barely tilted on its axis, has no seasons, though there are hints that it may have once looked and behaved much like Earth, including having oceans covering its rocky surface. But these days, our neighboring planet has an atmosphere so thick (55 times denser than Earth’s) it helps keep Venus at a searing 900 degrees Fahrenheit (465 degrees Celsius) year round — that’s hotter than the hottest home oven. This oppressive atmosphere also blots out the sky, making it impossible to stargaze from the surface. But Venus isn’t all bad. Despite the low quality of life, there is one benefit of living there: The Venusian year (225 Earth days) is shorter than its day (243 Earth days). That means you can celebrate your birthday every day on Venus! —Lonnie Shekhtman, science writer, NASA's Goddard Space Flight Center.

Massive Black Hole Shreds Passing Star

Video above: This artist’s rendering illustrates a star getting shredded by a black hole. When a star wanders too close to a black hole, intense tidal forces rip the star apart. In these events, called “tidal disruptions,” some of the stellar debris is flung outward at high speed while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for a few years. NASA’s Chandra X-ray Observatory, Swift Gamma-ray Burst Explorer, and ESA/NASA’s XMM-Newton collected different pieces of this astronomical puzzle in a tidal disruption event called ASASSN-14li, which was found in an optical search by the All-Sky Automated Survey for Supernovae (ASAS-SN) in November 2014. Video Credits: NASA's Goddard Space Flight Center.

4. Its gravity doesn’t turn us into noodles

Capturing the imaginations of scientists and sci-fi writers alike, black holes are extremely compact objects that do not let any light escape. The surface of a black hole is an area called the “event horizon,” a boundary beyond which nothing can ever return. Even if we were fortunate enough to have a spaceship that could travel to a relatively nearby black hole, its gravity is so strong that approaching too close would stretch and compress the spacecraft and everyone inside it into a noodle shape — a fate scientists call “spaghettification.” Making matters even weirder, time ticks by more slowly around a black hole. To someone watching from far away as a spaceship fell into the event horizon, the vehicle would appear to slow down more the closer it got — and never quite get there. Fortunately, there are no known black holes in the vicinity of Earth or anywhere in the solar system, so we’re safe for now. And we’re lucky that Earth has just the right amount of gravity — enough so we don’t go flying away, but not so much that we can’t stand up and run around. If you still think traveling to a black hole would be a good idea, check out this black hole safety video. —Elizabeth Landau, writer, NASA Headquarters.

Image above: An image of Jupiter. Image Credits: NASA/JPLCaltech/SwRI/MSSS/Kevin M. Gill.

5. We can enjoy a pleasant breeze

Jupiter’s breathtaking swirls of colorful cloud bands might make this planet an appealing vacation destination … for skydivers. They’d need to bring along their own oxygen, since Jupiter’s atmosphere is made mostly of hydrogen and helium (same as our Sun), with clouds of mostly ammonia. Descending through Jupiter’s clouds is for the most extreme thrill seekers. Given the planet’s strong gravity and super-fast rotation on its axis compared to Earth (10 hours vs. 24 hours), a skydiver would tumble 2.5 times faster than they would on Earth, while getting knocked around by winds raging between 270 and 425 miles per hour (430 to 680 kilometers per hour). Jupiter’s winds make Earth’s highest category hurricane feel like a breeze, and its lightning strikes are up to 1,000 times more powerful than ours. Even if a skydiver does make it through the hundreds of miles, or kilometers, of atmosphere, plus crushing air pressure and extreme heat, it’s not clear they’ll reach a solid surface. Scientist don’t know yet whether Jupiter, a giant planet that can fit 1,300 Earths inside of it, has a solid core. Having solid ground to stand is starting to sound like a luxury. —Staci Tiedeken, planetary science outreach coordinator, NASA’s Goddard Space Flight Center.

Image above: Jupiter's moon Io, the most volcanic body in the solar system, is seen in this 1997 image taken by NASA's Galileo spacecraft. Image Credits: NASA/JPL/University of Arizona.

6. It’s a sparkling globe of blue, white and green

In places where ocean tides are highest on Earth, the difference between low and high tide is about 50 feet (15 meters). Compare that to Io. This moon of Jupiter is caught in a tug-of-war between the planet’s massive gravity and the pulling of two neighboring moons, Europa and Ganymede. These forces cause Io's surface to regularly bulge up and down by as much as 330 feet (100 meters) — and we’re talking about rock, not water. All this motion has consequences: Io’s interior is very hot, making this moon the most volcanically active world in the solar system. Io, which from space looks like a moldy cheese pizza, has hundreds of volcanoes. Some erupt lava fountains dozens of miles (or kilometers) high. Between all the lava, a thin sulfur dioxide atmosphere and intense radiation from nearby Jupiter, Io doesn’t offer much of a beach vacation for humans. —Bill Dunford, writer and web producer, NASA's Jet Propulsion Laboratory.

Image above: This artist's concept of a lake at the north pole of Saturn's moon Titan illustrates raised rims and rampart-like features, such as those seen by NASA's Cassini spacecraft around the moon's Winnipeg Lacus. Image Credits: Credits: NASA/JPL-Caltech.

7. It’s got clear skies, sunny days and water we can swim in

If there is one place in the universe we know of that could compete with Earth as a home for humans, Titan is it. This satellite of Saturn is the second largest moon in our solar system after Ganymede. Titan is in some ways the most similar world to ours that we have found. Its thick atmosphere would remind us of home, though the air pressure there is slightly higher than Earth's. The atmosphere would defend humans against harmful radiation. Like Earth, Titan also has clouds, rain, lakes and rivers, and even a subsurface ocean of salty water. Even the moon’s terrain and landscape look eerily similar to some parts of Earth. While Titan sounds promising, it has major flaws. Chief among them is oxygen — there isn’t any in the atmosphere. And those lovely rivers and lakes? They’re made of liquid methane. So don’t pack your bathing suit just yet; our bodies are denser than the methane, so they’d sink like boulders. Another thing you’d miss on Titan is seeing the Sun above your head, dazzling against an azure sky. Not only is Titan much farther from the Sun than is Earth, its hazy atmosphere dims the sunlight, making daytime appear like twilight on Earth. —Lonnie Shekhtman, science writer, NASA's Goddard Space Flight Center.

Image above: Made from images taken by NASA's Galileo spacecraft in the late 1990s, this processed color view is one of the best images Earthlings have of Jupiter’s moon Europa. This little moon may be the best place in our solar system to look for life beyond Earth.Image Credits: NASA/JPL-Caltech/SETI  Institute.

8. Dry land exists! And the entire world isn’t smothered beneath miles of ice

Jupiter’s moon Europa is one of the best places to search for life beyond Earth. It may harbor more liquid water than all of Earth’s oceans combined. Just picture yourself standing on a warm, sandy beach, admiring the sunlight glimmering on an ocean that reaches from horizon to horizon. And then prepare to be disappointed. Europa’s ocean is global. It has no beach. No shore. Only ocean, all the way around. Sunlight doesn’t glimmer on the water and there are no waves because Europa’s ocean is hidden beneath miles — perhaps tens of miles — of ice that encases the entire moon. Europa is also tidally locked, meaning if a person stood on its Jupiter-facing side (like our Moon, one hemisphere always faces its parent planet), the solar system’s largest planet would loom overhead and never set. A sublime setting for a romantic stroll? No. Europa has a practically nonexistent atmosphere and brutally cold temperatures ranging from about minus 210 to minus 370 degrees Fahrenheit (minus 134 to minus 223 degrees Celsius). A spacesuit might help with the temperature and pressure, but it can’t protect against those pesky atomic particles captured in Jupiter’s magnetic field, endlessly lashing Europa with such energy that they can blast apart molecules and ionize atoms. Europa’s ionizing radiation would damage or destroy cells in the human body, leading to radiation sickness. —Jay R. Thompson, writer, NASA's Jet Propulsion Laboratory.

Image above: Kepler-7b (right), which is 1.5 times the radius of Jupiter (left), is the first exoplanet to have its clouds mapped. The cloud map was produced using data from NASA's Kepler and Spitzer space telescopes. Image Credits: NASA/JPL.

9. Cream puff clouds that come and go

With more than 4,000 planets discovered so far outside our solar system, called “exoplanets,” we don’t know of any that offers the comforts of Earthly living — and many would be downright nightmares. Take Kepler-7b, for example, a gas giant with roughly the same density as foam board. That means it could actually float in a bathtub (fun fact: so could Saturn). Like other exoplanets called “hot Jupiters,” this one is really close to its star — a “year,” one orbit, takes just five Earth days. One side always faces the star, just like one side of the Moon always faces Earth. That means it’s always hot and light on one half of this planet; on the other, night never ends. If you’re bummed out by cloudy days on Earth, consider that one side of Kepler-7b always has thick, unmoving clouds, and those clouds may even be made of evaporated rock and iron. And at more than 2,400 degrees Fahrenheit (1,356 Celsius), Kepler-7b would be a real roaster to visit, especially on the dayside. It’s amazing to learn about how different exoplanets can be from Earth, but we’re glad we don’t live on Kepler-7b. —Kristen Walbolt, digital and social media producer/strategist, NASA's Jet Propulsion Laboratory.

Wanderers - A short film by Erik Wernquist

Wanderers

Film above: Wanderers is a vision of humanity's expansion into the Solar System, based on scientific ideas and concepts of what our future in space might look like, if it ever happens. The locations depicted in the film are digital recreations of actual places in the Solar System, built from real photos and map data where available.

Without any apparent story, other than what you may fill in by yourself, the idea of the film is primarily to show a glimpse of the fantastic and beautiful nature that surrounds us on our neighboring worlds - and above all, how it might appear to us if we were there.

As some may notice I have borrowed ideas and concepts from science fiction authors such as Kim Stanley Robinson and Arthur C. Clarke, just to name a few. And visually, I of course owe many tips of my hat to painter Chesley Bonestell - the legendary master of space art.

More directly, with kind permission from Ann Druyan I have also borrowed the voice of astronomer and author Carl Sagan to narrate the film. The audio I used are excerpts from his own reading of his book 'Pale Blue Dot: A Vision of the Human Future in Space' (1994, Random House) - needless to say, a huge inspiration for this film.

Film Credits:

VISUALS BY - Erik Wernquist - erik@erikwernquist.com
MUSIC BY - Cristian Sandquist - cristiansandquist@mac.com
WRITTEN AND NARRATED BY - Carl Sagan - from his book 'Pale Blue Dot' http://www.penguinrandomhouse.com/boo..., courtesy of Ann Druyan, copyright by Democritus Properties, LLC, with all rights reserved
COLOR GRADE BY - Caj Müller/Beckholmen Film - caj@beckholmenfilm.se
LIVE ACTION PHOTOGRAPHY BY - Mikael Hall/Vidiotism - mikael@vidiotism.com
LIVE ACTION PERFORMANCE BY - Anna Nerman, Camilla Hammarström, Hanna Mellin
VOCALIST - Nina Fylkegård - nina@ladystardust.se
THANK YOU - Johan Persson, Calle Herdenberg, Micke Lindgren, Satrio J. Studt, Tomas Axelsson, Christian Lundqvist, Micke Lindell, Sigfrid Söderberg, Fredrik Strage, Johan Antoni, Henrik Johansson, Michael Uvnäs, Hanna Mellin
THIS FILM WAS MADE WITH USE OF PHOTOS AND TEXTURES FROM:
NASA/JPL, NASA/CICLOPS, NASA/Goddard Space Flight Center Scientific Visualization Studio, ESA, John Van Vliet, Björn Jonsson (and many others, of which I unfortunately do not know the names).

Related links:

Solar System: https://www.nasa.gov/topics/solarsystem/index.html

Exoplanets: https://www.nasa.gov/content/the-search-for-life

Universe: https://www.nasa.gov/topics/solarsystem/index.html

Goddard Space Flight Center (GSFC): https://www.nasa.gov/centers/goddard/home/index.html

Jet Propulsion Laboratory (JPL): https://www.nasa.gov/centers/jpl/home/index.html

Images (mentioned), Animation (mentioned), Videos (mentioned), Film (mentioned), Text, Credits: NASA/Svetlana Shekhtman/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

This black-hole collision just made gravitational waves even more interesting

Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) logo.

21 April 2020

An unprecedented signal from unevenly sized objects gives astronomers rare insight into how black holes spin. 

Image above: A visualization of a collision between two differently sized black holes. Image Credits: N. Fischer, H. Pfeiffer, A. Buonanno (Max Planck Institute for Gravitational Physics), Simulating eXtreme Spacetimes (SXS) Collaboration.

Gravitational-wave astronomers have for the first time detected a collision between two black holes of substantially different masses — opening up a new vista on astrophysics and on the physics of gravity. The event offers the first unmistakable evidence from these faint space-time ripples that at least one black hole was spinning before merging, giving astronomers rare insight into a key property of these these dark objects.

“It’s an exceptional event,” said Maya Fishbach, an astrophysicist at the University of Chicago in Illinois. Similar mergers on which data have been published all took place between black holes with roughly equal masses, so this new one dramatically upsets that pattern, she says. The collision was detected last year, and was unveiled on 18 April by Fishbach and her collaborators at a virtual meeting of the American Physical Society, held entirely online because of the coronavirus pandemic.

GW190412: Binary Black Hole Merger

The Laser Interferometer Gravitational-Wave Observatory (LIGO) — a pair of twin detectors based in Hanford, Washington, and Livingston, Louisiana — and the Virgo observatory near Pisa, Italy, both detected the event, identified as GW190412, with high confidence on 12 April 2019. The LIGO–Virgo collaboration, which includes Fishbach, posted its findings on the arXiv preprint server.

LIGO made the first discovery of gravitational waves in September 2015, detecting the space-time ripples from two merging black holes. LIGO, later joined by Virgo, subsequently made ten more detections in two observing runs that ended in 2017: nine more black-hole mergers and one collision of two neutron stars, which helped to explain the origin of the Universe’s heavy chemical elements.

The third and most recent run started on 1 April 2019 and ended on 27 March 2020, with a month-long break in October. Greatly improved sensitivity enabled the network to accumulate around 50 more ‘candidate events’ at a rate of roughly one per week. Until now, the international collaboration had unveiled only one other event from this observation period — a second merger between two neutron stars, dubbed GW190425, that was revealed in January.

Related links:

Laser Interferometer Gravitational-Wave Observatory (LIGO): https://www.ligo.caltech.edu/page/what-is-ligo

Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut): https://www.aei.mpg.de/

Image (mentioned), Video, Text, Credits: Nature/Davide Castelvecchi/Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut).

Greetings, Orbiter.ch

ATLAS searches for rare Higgs boson decays into a photon and a Z boson

CERN - ATLAS Experiment logo.

April 21, 2020

Image above: Event display of a candidate Higgs-boson decay to a photon and a Z boson, where the Z boson decays to two muons (shown in red). Green rectangles correspond to energy deposits in cells of the electromagnetic calorimeter, while yellow rectangles correspond to energy deposits in cells of the hadron calorimeter. (Image: ATLAS Collaboration/CERN).

The Higgs boson was discovered by the ATLAS and CMS Collaborations at CERN’s Large Hadron Collider (LHC) in 2012 through its decays into pairs of pho­tons, W bosons and Z bosons. Since then, physicists at these experiments have gained great insight into the properties of the Higgs boson through the study of its different production and decay processes. Decays to pairs of tau leptons and bottom quarks were established, as was the coupling to top quarks. However, the question remains whether the Higgs boson may also interact with yet-unknown particles or forces.

Eight years after its discovery, ATLAS has observed nearly 90% of all Higgs-boson decays predicted by the Standard Model. A rare decay of the Higgs boson that has yet to be seen is that to a Z boson and a photon (Zγ). This decay is of particular interest to physicists as it proceeds through processes involving heavy “virtual” (possibly new) particles, which could modify its rate.

The ATLAS Collaboration has just released a new result searching for the Higgs-boson decay to Zγ. This result uses the full LHC Run-2 dataset, analysing almost four times as many Higgs-boson events as the previous ATLAS result.

The new ATLAS result examines the full dataset collected during Run 2 of the LHC in search of the rare Higgs boson decay to a Z boson and a photon.

According to the Standard Model, 0.15% of Higgs bosons decay to Zγ – a rate comparable to the Higgs-boson decay to two photons, one of the discovery channels. However, unlike photons, Z bosons decay almost instantly and cannot be directly observed. Instead, the Z bosons are reconstructed through their decays into electron or muon pairs. As less than 7% of Z bosons decay in this way, only a tiny expected signal of about 1 in 10,000 Standard Model Higgs bosons can be probed.

Graphic above: Figure 1: Weighted Zγ mass distribution of events satisfying the H→Zγ selection in data. Events are weighted by the expected signal and background in a Zγ mass window containing 68% of the expected signal. The solid blue curve shows the fitted signal plus background model while the dashed line shows the model of the background component of fit. (Image: ATLAS Collaboration/CERN).

To separate Higgs-boson events from abundant background processes, ATLAS physicists performed a fit to the distribution of the mass of the reconstructed Z boson and photon. This fit simultaneously determines the number of signal and background events by utilising the different shapes of the signal (narrow peak) and background processes (smooth distribution).

To enhance the sensitivity of the search, physicists separated the potential Higgs-boson events into multiple categories, each with different expected signal-to-background ratios. One of these categories, where the Higgs boson is produced together with two forward jets via the interaction of two weak bosons, used a multivariate discriminant (or “boosted decision tree”) to distinguish it from the other Higgs-boson production modes. Other categories were characterised by the momentum of the photon or the Higgs-boson candidate, or whether the Z boson decayed into electron or muon pairs.

Physicists examined all of these categories simultaneously, studying the distribution of the mass of the reconstructed Z boson and photon in selected events to look for an excess caused by the decays of Higgs bosons to Zγ. Figure 1 shows the Z-boson-plus-photon mass distribution combined over all categories, with the results of the fit overlaid.

A signal yield about twice that expected from the Standard Model, equivalent to a significance of 2.2 standard deviations (5 needed to declare an observation) was found in the data. The result allows ATLAS physicists to exclude, at a 95% confidence level, production rates more than 3.6 larger than what is predicted by the Standard Model. More data are needed to hone in on the Higgs boson decay to Zγ.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 23 Member States.

Links:

- CERN LHC Seminar: Searches for rare and invisible Higgs boson decays and for high-mass resonances with the ATLAS detector by Douglas Michael Schaefer and Takuya Nobe: https://indico.cern.ch/event/868253/

- Searches for the Zγ decay mode of the Higgs boson and for new high-mass resonances in proton-proton collisions at 13 TeV with the ATLAS detector (JHEP 10 (2017) 112, see figures):
https://link.springer.com/article/10.1007%2FJHEP10%282017%29112

- Exploring rare decays of the Higgs boson, Physics Briefing, 11 August 2017:
https://atlas.cern/updates/physics-briefing/exploring-rare-decays-higgs-boson

- See also the full lists of ATLAS Conference Notes and ATLAS Physics Papers:
https://twiki.cern.ch/twiki/bin/view/AtlasPublic/CONFnotes

https://twiki.cern.ch/twiki/bin/view/AtlasPublic/WebHome#Physics_papers

Related links:

Higgs boson: http://atlas.cern/updates/atlas-feature/higgs-boson

ATLAS experiment: https://home.cern/science/experiments/atlas

ATLAS Collaboration: https://atlas.cern/authors/atlas-collaboration

For more information about the European Organization for Nuclear Research (CERN), visit: https://home.web.cern.ch/

Image, Graphic, Text, Credits: CERN/ATLAS Collaboration.

Greetings, Orbiter.ch

For the first time, a spacecraft has returned an aging satellite to service

Northrop Grumman logo.

April 21, 2020

It’s a big step forward for satellite servicing.

View of IS-901 satellite from Mission Extension Vehicle-1’s “near hold” position

In a triumph for the nascent industry of "satellite servicing," an aging communications satellite has returned to service in geostationary orbit.

Northrop Grumman announced Friday that its Mission Extension Vehicle-1, or MEV-1, has restored the Intelsat 901 satellite and relocated it into a position to resume operations.

"We see increased demand for our connectivity services around the world, and preserving our customers’ experience using innovative technology such as MEV-1 is helping us meet that need,” Intelsat Chief Services Officer Mike DeMarco said in a news release.

After launching on a Proton rocket last October, Northrop Grumman's servicing vehicle used its mechanical docking system to latch onto Intelsat 901 on February 25, at an altitude of 36,000km above Earth. Prior to this, no two commercial spacecraft had ever docked in orbit before.

Since then, the MEV-1 servicer has assumed navigation of the combined spacecraft stack, reducing the satellite's inclination by 1.6 degrees and relocating it to a new orbital location, at 332.5° east. Intelsat then transitioned about 30 of its commercial and government customers to the satellite two weeks ago. The transition of service took approximately six hours and was successful.

Based on the agreement between Northrop and Intelsat, MEV-1 will provide five years of life extension services to the satellite before moving it into a graveyard orbit. MEV-1 will then be available to provide additional mission extension services, Northrop said, including orbit raising, inclination corrections, and inspections. Northrop is already building a second MEV to service another Intelsat satellite, 1002, later this year.

MEV-1 Mission with images

This satellite servicing milestone comes as both low-Earth orbit as well as geostationary space—where large, expensive communications satellites are often placed high above the planet to hold their position over the ground—are becoming more crowded. The availability of a service such as that offered by MEV-1 offers satellite providers both the ability to extend the lifetime of aging assets, but also to potentially remove those they have lost control of from the ground.

These kinds of services are generally seen in the space community as important to keeping orbit as decluttered as possible in the coming decades, so it is good that this demonstration case worked out well.

Related links:

Intelsat: http://www.intelsat.com/

Northrop Grumman: https://www.northropgrumman.com/

Image, Video, Text, Credits: Ars Technica/Eric Berger/Northrop Grumman.

Greetings, Orbiter.ch

Exoplanet Apparently Disappears in Latest Hubble Observations

NASA - Hubble Space Telescope patch.

April 20, 2020

Now you see it, now you don't.

What astronomers thought was a planet beyond our solar system has now seemingly vanished from sight. Though this happens in science fiction, such as Superman's home planet Krypton exploding, astronomers are looking for a plausible explanation.

Image above: This artist's illustration depicts the collision of two 125-mile-wide icy, dusty bodies orbiting the bright star Fomalhaut, located 25 light-years away. Image Credits: ESA, NASA and M. Kornmesser.

One interpretation is that, rather than being a full-sized planetary object, which was first photographed in 2004, it could instead be a vast, expanding cloud of dust produced in a collision between two large bodies orbiting the bright nearby star Fomalhaut. Potential follow-up observations might confirm this extraordinary conclusion.

"These collisions are exceedingly rare and so this is a big deal that we actually get to see one," said András Gáspár of the University of Arizona, Tucson. "We believe that we were at the right place at the right time to have witnessed such an unlikely event with NASA's Hubble Space Telescope."

Image above: This diagram simulates what astronomers, studying Hubble Space Telescope observations, taken over several years, consider evidence for the first-ever detection of the aftermath of a titanic planetary collision in another star system. The color-tinted Hubble image on the left is of a vast ring of icy debris encircling the star Fomalhaut, located 25 light-years away. The star is so brilliant that a black occulting disk is used to block out its glare so that the dust ring can be photographed. In 2008, astronomers saw what they thought was the first direct image of a planet orbiting far from the star. However, by 2014, the planet candidate faded below Hubble's detection. The best interpretation is that the object wasn't ever a fully formed planet at all, but an expanding cloud of dust from a collision between two minor bodies, each about 125 miles across. The diagram at the right is based on a simulation of the expanding and fading cloud. The cloud, made of very fine dust particles, is currently estimated to be over 200 million miles across. Smashups like this are estimated to happen around Fomalhaut once every 200,000 years. Therefore, Hubble was looking at the right place at the right time to capture this transient event. Image Credits: NASA, ESA, and A. Gáspár and G. Rieke (University of Arizona).

"The Fomalhaut system is the ultimate test lab for all of our ideas about how exoplanets and star systems evolve," added George Rieke of the University of Arizona's Steward Observatory. "We do have evidence of such collisions in other systems, but none of this magnitude has been observed in our solar system. This is a blueprint of how planets destroy each other."

The object, called Fomalhaut b, was first announced in 2008, based on data taken in 2004 and 2006. It was clearly visible in several years of Hubble observations that revealed it was a moving dot. Until then, evidence for exoplanets had mostly been inferred through indirect detection methods, such as subtle back-and-forth stellar wobbles and shadows from planets passing in front of their stars.

Unlike other directly imaged exoplanets, however, nagging puzzles arose with Fomalhaut b early on. The object was unusually bright in visible light, but did not have any detectable infrared heat signature. Astronomers conjectured that the added brightness came from a huge shell or ring of dust encircling the planet that may possibly have been collision-related. The orbit of Fomalhaut b also appeared unusual, possibly very eccentric.

"Our study, which analyzed all available archival Hubble data on Fomalhaut revealed several characteristics that together paint a picture that the planet-sized object may never have existed in the first place," said Gáspár.

The team emphasizes that the final nail in the coffin came when their data analysis of Hubble images taken in 2014 showed the object had vanished, to their disbelief. Adding to the mystery, earlier images showed the object to continuously fade over time, they say. "Clearly, Fomalhaut b was doing things a bona fide planet should not be doing," said Gáspár.

The interpretation is that Fomalhaut b is slowly expanding from the smashup that blasted a dissipating dust cloud into space. Taking into account all available data, Gáspár and Rieke think the collision occurred not too long prior to the first observations taken in 2004. By now the debris cloud, consisting of dust particles around 1 micron (1/50th the diameter of a human hair), is below Hubble's detection limit. The dust cloud is estimated to have expanded by now to a size larger than the orbit of Earth around our Sun.

Hubble Movie Captures Protoplanetary Collision in the Fomalhaut Star System

Video above: This video simulates what astronomers, studying Hubble Space Telescope observations, consider evidence for the first-ever detection of the aftermath of a titanic planetary collision in another star system. The color-tinted Hubble image on the left is of a vast ring of icy debris encircling the star Fomalhaut, located 25 light-years away. The animated diagram on the right is a simulation of the expanding and fading cloud, based on Hubble observations taken over a period of several years. bVideo Credits: NASA, ESA, and A. Gáspár and G. Rieke (University of Arizona).

Equally confounding is that the team reports that the object is more likely on an escape path, rather than on an elliptical orbit, as expected for planets. This is based on the researchers adding later observations to the trajectory plots from earlier data. "A recently created massive dust cloud, experiencing considerable radiative forces from the central star Fomalhaut, would be placed on such a trajectory," said Gáspár. "Our model is naturally able to explain all independent observable parameters of the system: its expansion rate, its fading and its trajectory."

Because Fomalhaut b is presently inside a vast ring of icy debris encircling the star, colliding bodies would likely be a mixture of ice and dust, like the comets that exist in the Kuiper belt on the outer fringe of our solar system. Gáspár and Rieke estimate that each of these comet-like bodies measured about 125 miles (200 kilometers) across (roughly half the size of the asteroid Vesta).

Hubble Space Telescope (HST). Animation Credits: NASA/ESA

According to the authors, their model explains all the observed characteristics of Fomalhaut b. Sophisticated dust dynamical modeling done on a cluster of computers at the University of Arizona shows that such a model is able to fit quantitatively all the observations. According to the author's calculations, the Fomalhaut system, located about 25 light-years from Earth, may experience one of these events only every 200,000 years.

Gáspár and Rieke — along with other members of an extended team — will also be observing the Fomalhaut system with NASA's upcoming James Webb Space Telescope in its first year of science operations. The team will be directly imaging the inner warm regions of the system, spatially resolving for the first time the elusive asteroid-belt component of an extrasolar planetary system. The team will also search for bona fide planets orbiting Fomalhaut that might be gravitationally sculpting the outer disk. They will also analyze the chemical composition of the disk.

Their paper, "New HST [Hubble] data and modeling reveal a massive planetesimal collision around Fomalhaut" is being published on April 20, 2020, in the Proceedings of the National Academy of Sciences.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Related links:

Proceedings of the National Academy of Sciences: http://www.pnas.org/

Exoplanets: https://www.nasa.gov/content/the-search-for-life

Hubble Space Telescope (HST): https://www.nasa.gov/mission_pages/hubble/main/index.html

Images (mentioned), Animation (mentioned), Video, Text, Credits: NASA/Rob Garner/GSFC/Claire Andreoli/STSI/Ray Villard/University of Arizona/András Gáspár.

Greetings, Orbiter.ch