Two NASA Astronauts Set to Go on Their Third Spacewalk This Year

ISS  Expedition 56 Mission patch.

June 12, 2018

NASA astronauts Ricky Arnold and Drew Feustel are set to go on their third spacewalk together this year on Thursday at the International Space Station. Their new Expedition 56 crewmates Serena Auñón-Chancellor and Alexander Gerst are training today to support the two spacewalkers.

Image above: NASA astronauts Ricky Arnold and Drew Feustel are suited up inside U.S. spacesuits for a fit check verification ahead of a spacewalk that took place May 16, 2016. Image Credit: NASA.

Arnold and Feustel will begin Thursday’s spacewalk at 8:10 a.m. to install new high definition cameras to support upcoming commercial crew missions from SpaceX and Boeing to the orbital laboratory. The first uncrewed test missions are planned to begin at the end of the year. The cameras will provide improved views of the commercial crew vehicles as they approach and dock to the station. NASA TV will provide complete live coverage of the 211th space station spacewalk starting at 6:30 a.m.

Auñón-Chancellor and Gerst, who just arrived at the station on Friday, will assist the spacewalkers on Thursday. Gerst will help the spacewalkers in and out of their spacesuits. Auñón-Chancellor will operate the Canadarm2 robotic arm. The duo practiced today on a computer the robotics procedures necessary to maneuver a spacewalker to and from the worksite on the starboard side of the station’s truss structure.

Image above: Flying over North Pacific Ocean, seen by EarthCam on ISS, speed: 27'611 Km/h, altitude: 409,26 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam's from ISS on June 12, 2018 at 21:39 UTC. Image Credits: Orbiter.ch Aerospace/Roland Berga.

Arnold and Feustel had some extra time today to work on science and maintenance activities. Arnold worked with the Microgravity Science Glovebox to troubleshoot a semiconductor crystal growth experiment. Feustel performed some plumbing work in the Tranquility module before relocating a pair of incubator units to support new experiments being delivered on the next SpaceX Dragon cargo mission. Finally, the duo readied the Quest airlock and their spacesuits for Thursday morning’s spacewalk.

Related links:

Spacewalk: https://www.nasa.gov/mission_pages/station/spacewalks

NASA TV: https://www.nasa.gov/nasatv

Semiconductor crystal growth: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=1148

SpaceX Dragon: https://www.nasa.gov/spacex

Expedition 56: https://www.nasa.gov/mission_pages/station/expeditions/expedition56/index.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

Images (mentioned), Text, Credits: NASA/Mark Garcia/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.ch

NASA Flies Large Unmanned Aircraft in Public Airspace Without Chase Plane for First Time

NASA - Armstrong Flight Research Center patch.

June 12, 2018

NASA’s remotely-piloted Ikhana aircraft, based at the agency’s Armstrong Flight Research Center in Edwards, California, successfully flew its first mission in the National Airspace System without a safety chase aircraft on Tuesday. This historic flight moves the United States one step closer to normalizing unmanned aircraft operations in the airspace used by commercial and private pilots.

Flying these large remotely-piloted aircraft over the United States opens the doors to all types of services, from monitoring and fighting forest fires, to providing new emergency search and rescue operations. The technology in this aircraft could, at some point, be scaled down for use in other general aviation aircraft.

Image above: Aircraft maintenance crews at NASA‘s Armstrong Flight Research Center prepare the remotely-piloted Ikhana aircraft for a test flight June 12, 2018. The test flight was performed to validate key technologies and operations necessary for the Federal Aviation Administration's approval to fly the aircraft in the public airspace without a safety chase aircraft. Image Credits: NASA/Ken Ulbrich.

“This is a huge milestone for our Unmanned Aircraft Systems Integration in the National Airspace System project team,” said Ed Waggoner, NASA’s Integrated Aviation Systems Program director. “We worked closely with our Federal Aviation Administration colleagues for several months to ensure we met all their requirements to make this initial flight happen.”

Flights of large craft like Ikhana, have traditionally required a safety chase aircraft to follow the unmanned aircraft as it travels through the same airspace used by commercial aircraft. The Ikhana flew in accordance with the Federal Aviation Administration’s (FAA) Technical Standard Order 211 -- Detect and Avoid Systems -- and Technical Standard Order 212 -- Air-to-Air Radar for Traffic Surveillance.

The FAA granted NASA special permission to conduct this flight under the authority of a Certificate of Waiver or Authorization on March 30. The certificate permitted Ikhana’s pilot to rely on the latest Detect and Avoid technology, enabling the remote pilot on the ground to see and avoid other aircraft during the flight.

Image above: NASA’s remotely-piloted Ikhana aircraft, based at the agency’s Armstrong Flight Research Center, is flown in preparation for its first mission in public airspace without a safety chase aircraft. Image Credits: NASA/Carla Thomas.

NASA successfully worked with its industry partners to develop a standard for Detect and Avoid technologies, complied with the requirements of the FAA Technical Standard Orders, and garnered flight approval from the FAA.

The Ikhana aircraft was equipped with detect and avoid technologies, including an airborne radar developed by General Atomics Aeronautical Systems, Inc., a Honeywell Traffic Alert and Collision Avoidance System, a Detect and Avoid Fusion Tracker, and an Automatic Dependent Surveillance-Broadcast capability – a surveillance technology where the aircraft determines its position via satellite navigation and periodically broadcasts this information so other aircraft can track it.

The flight took off from Edwards Air Force Base in California and entered controlled air space almost immediately. Ikhana flew into the Class-A airspace, where commercial airliners fly, just west of Edwards at an altitude of about 20,000 feet. The aircraft then turned north toward Fresno, requiring air traffic control to be transferred from the Los Angeles Air Route Traffic Control Center to the Oakland Air Route Traffic Control Center. On the return trip, the pilot headed south toward Victorville, California, requiring communication control to be transferred back to Los Angles.

Image above: Engineers at NASA‘s Armstrong Flight Research Center monitor the remotely-piloted Ikhana aircraft from a mission control room during a test flight June 12, 2018. Image Credits: NASA/Ken Ulbrich.

During the return flight, the pilot began a gentle decent over the city of Tehachapi, California, into Class E airspace -- about 10,000 feet -- where general aviation pilots fly. The pilot initiated an approach into Victorville airport at 5,000 feet, coordinating in real time with air traffic controllers at the airport. After successfully executing all of these milestones, the aircraft exited the public airspace and returned to its base at Armstrong.

“We are flying with a suite of sophisticated technology that greatly enhances the safety capabilities of pilots flying large unmanned aircraft in the National Airspace System,” said Scott Howe, Armstrong test pilot. “We took the time to mitigate the risks and to ensure that we, as a program, were prepared for this flight.”

Tuesday’s flight was the first remotely-piloted aircraft to use airborne detect and avoid technology to meet the intent of the FAA’s “see and avoid” rules, with all test objectives successfully accomplished.

For more information on NASA’s Unmanned Aircraft Systems Integration in the National Airspace System project, visit: https://go.nasa.gov/2sx9VCn

For more information about NASA’s aeronautics research, visit: https://www.nasa.gov/aeroresearch

Images (mentioned), Text, Credits: NASA/J.D. Harrington/Karen Northon/Armstrong Flight Research Center/Rebecca Richardson.

Greetings, Orbiter.ch

GRACE-FO Turns on 'Range Finder,' Sees Mountain Effects

NASA - GRACE-FO Mission logo.

June 12, 2018

Recently Launched Twin Satellites Create 'The Himalaya Plot'

Less than three weeks after launch, the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission has successfully completed its first mission phase and demonstrated the performance of the precise microwave ranging system that enables its unique measurements of how mass migrates around our planet.

The twin spacecraft launched May 22 from California's Vandenberg Air Force Base. NASA and German Research Centre for Geosciences (GFZ) engineers and mission controllers at the German Space Operations Center in Oberpfaffenhofen then spent the first few days completing the mission's launch and early operations phase and moving into an 85-day in-orbit checkout period. Science operations will begin when that period has been successfully completed.

Image above: Along the satellites' ground track (top), the inter-spacecraft distance between them changes as the mass distribution underneath (i.e., from mountains, etc.) varies. The small changes measured by the Microwave Ranging Instrument (middle) agree well with topographic features along the orbit (bottom). Image Credits: NASA/JPL-Caltech/GFZ.

During the initial phase, the twin GRACE-FO satellites were maneuvered into their operational orbit formation approximately 137 miles (220 kilometers) apart. Spacecraft systems were powered on, checked out and found to be performing as expected. Engineers also activated both primary instruments: the accelerometers, which measure forces on the satellites other than gravity, such as atmospheric drag or solar radiation pressure; and the microwave ranging instruments, which precisely measure the distance changes between the two satellites as they orbit Earth. Variations in Earth's gravity field caused by changes in the distribution of Earth's mass on and beneath the planet's surface -- such as groundwater withdrawal and ice melt -- cause the distance between the two satellites to vary ever so slightly.

The GRACE-FO microwave ranging instruments allow distance measurements with a precision better than one micron -- less than the diameter of a blood cell, or a tenth the width of a human hair.

Image above: Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites. Image Credit: NASA.

During any single orbit of the satellites, some of the largest gravity variations on Earth seen in the satellite ranging data are due to massive mountain ranges. To demonstrate the initial performance of GRACE-FO's microwave ranging system, the team examined its measurements of changes in the distance between the two satellites as they flew over the Himalayas. The results are shown in a figure that team members dubbed "The Himalaya Plot," which may sound like the name of a mystery movie. However, the figure's working name actually refers to the distance changes measured by the microwave ranging system as the satellites flew over the mountains. The plot's wavy lines show how the distance between the satellites varies as the satellites pass over oceans, land areas, and particularly mountains as they orbit Earth. The observed inter-satellite distance changes, which can be as large as hundreds of microns, are in good agreement with expectations. These results give the team confidence that the mission's key microwave ranging system is performing well.

By measuring even minute changes in distance between the satellites, GRACE-FO can detect the month-to-month variations in Earth's gravity field caused by the movement of mass as small as about a half-inch (1 centimeter) of water over an area of about 200 miles (320 kilometers) in diameter.

GRACE-FO data will provide unique insights into Earth's changing climate, including large-scale changes in our planet's ice sheets and glaciers; Earth system processes that define our environment, such as droughts and earthquakes; and even the impacts of some human activities, such as changes in the levels of aquifers resulting from pumping underground water for use in agriculture. GRACE-FO observations promise to provide far-reaching benefits to society.

For more information on GRACE-FO, visit: https://www.nasa.gov/gracefo

Images (mentioned), Text, Credits: NASA/JPL/Alan Buis.

Greetings, Orbiter.ch

NASA’s Fermi Satellite Celebrates 10 Years of Discoveries

NASA - Fermi Gamma-ray Space Telescope logo.

June 11, 2018

On June 11, NASA’s Fermi Gamma-ray Space Telescope celebrates a decade of using gamma rays, the highest-energy form of light in the cosmos, to study black holes, neutron stars, and other extreme cosmic objects and events.

“Fermi’s first 10 years have produced numerous scientific discoveries that have revolutionized our understanding of the gamma-ray universe,” said Paul Hertz, Astrophysics Division director at NASA Headquarters in Washington.

NASA's Fermi Satellite Celebrates 10 Years of Discoveries

Video above: Watch how NASA’s Fermi Gamma-ray Space Telescope has revolutionized our understanding of the high-energy sky over its first 10 years in space. Video Credits: NASA’s Goddard Space Flight Center.

By scanning the sky every three hours, Fermi’s main instrument, the Large Area Telescope (LAT), has observed more than 5,000 individual gamma-ray sources, including an explosion called GRB 130427A, the most powerful gamma-ray burst scientists have detected.

In 1949, Enrico Fermi — an Italian-American pioneer in high-energy physics and Nobel laureate for whom the mission was named — suggested that cosmic rays, particles traveling at nearly the speed of light, could be propelled by supernova shock waves. In 2013, Fermi’s LAT used gamma rays to prove these stellar remnants are at least one source of the speedy particles.

Fermi’s all-sky map, produced by the LAT, has revealed two massive structures extending above and below the plane of the Milky Way. These two “bubbles” span 50,000 light-years and were probably produced by the supermassive black hole at the center of the galaxy only a few million years ago.

Images above: These images encapsulate nearly 30 years of gamma-ray astrophysics. On the left is a view of the gamma-ray sky created using data taken by Fermi’s predecessor, the Compton Gamma Ray Observatory’s Energetic Gamma Ray Experiment Telescope, over nine years of observations. Brighter colors indicated a larger number of gamma rays. On the right is the sharper, more detailed all-sky map produced by the Fermi Gamma-ray Space Telescope using nine years of data collected from 2008 to 2017. Images Credits: NASA/EGRET Team (above) and NASA/DOE/Fermi LAT Collaboration (below).

“The astronomy of gamma rays is the science of extremes,” said Julie McEnery, the Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Extreme gravity, extreme magnetic fields — Fermi has opened a window on to some of the most interesting physics and structures in the universe.”

The Gamma-ray Burst Monitor (GBM), Fermi’s secondary instrument, can see the entire sky at any instant, except the portion blocked by Earth. The satellite has observed over 2,300 gamma-ray bursts, the most luminous events in the universe. Gamma-ray bursts occur when massive stars collapse or neutron stars or black holes merge and drive jets of particles at nearly the speed of light. In those jets, matter travels at different speeds and collides, emitting gamma rays.

On Aug. 17, 2017, Fermi detected a gamma-ray burst from a powerful explosion in the constellation Hydra. At almost the same time, the National Science Foundation’s Laser Interferometer Gravitational-wave Observatory detected ripples in space-time from the same event, the merger of two neutron stars. This was the first time light and gravitational waves were detected from the same source. Scientists also used another gamma-ray burst detected by Fermi to confirm Einstein’s theory that space-time is smooth and continuous.   

The GBM has also spotted over 5,000 terrestrial gamma-ray flashes in Earth’s atmosphere associated with thunderstorms, as well as particles of antimatter those flashes can produce.

Image above: An illustration of the Fermi Gamma-ray Space Telescope, which has now been studying the extreme universe for a decade. Image Credit: NASA’s Goddard Space Flight Center/Conceptual Image Lab.

“Fermi has fundamentally improved our understanding of how the universe operates,” said David Thompson, a Fermi deputy project scientist at Goddard. “This spacecraft has both provided evidence for long-cherished theories and has also forced the scientific community to reevaluate some of its assumptions.”

But space can be a difficult working environment. On April 3, 2012, Fermi dodged a potential collision with Cosmos 1805, a defunct Soviet Cold War spy satellite, when the team fired Fermi’s decommissioning thrusters to move it to safety.

Fermi experienced its first hardware failure on March 16, 2018, when one of its solar panels became stuck. The Fermi team has adopted a new observation strategy to accommodate the jammed solar panel, and both instruments continue to scan the gamma-ray universe. 

“The Fermi observatory has so much flexibility that this glitch has only minor impact on science operations,” McEnery said. “Fermi is well prepared to continue operations for many years, and we look forward to many more discoveries about the high-energy universe.”

The Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. Fermi was developed in collaboration with the U.S. Department of Energy, with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

For more information on Fermi, visit: https://www.nasa.gov/fermi​

Large Area Telescope (LAT): https://fermi.gsfc.nasa.gov/science/instruments/lat.html

Gamma-ray Burst Monitor (GBM): https://fermi.gsfc.nasa.gov/science/instruments/gbm.html

Images (mentioned), Video (mentioned), Text, Credits: NASA/Rob Garner/Goddard Space Flight Center, by Jeanette Kazmierczak.

Greetings, Orbiter.ch

Opportunity Hunkers Down During Dust Storm

NASA - Mars Exploration Rover B (MER-B) patch.

June 11, 2018

NASA Mars Exploration Rover Status Report

Updated at 4:30 p.m. PDT on June 10, 2018

NASA engineers received a transmission from Opportunity on Sunday morning — a positive sign despite the worsening dust storm. Data from the transmission let engineers know the rover still has enough battery charge to communicate with ground controllers at NASA’s Jet Propulsion Laboratory in Pasadena, California. Science operations remain suspended.

Sunday's transmission was especially good news considering the dust storm has intensified in the past several days. A dark, perpetual night has settled over the rover's location in Mars' Perseverance Valley. The storm's atmospheric opacity — the veil of dust blowing around, which can blot out sunlight -- is now much worse than a 2007 storm that Opportunity weathered. The previous storm had an opacity level, or tau, somewhere above 5.5; this new storm had an estimated tau of 10.8 as of Sunday morning.

Opportunity's team has requested additional communications coverage from NASA's Deep Space Network, a global system of antennas that talks to all the agency's deep space probes.

Image above: This global map of Mars shows a growing dust storm as of June 6, 2018. The map was produced by the Mars Color Imager (MARCI) camera on NASA's Mars Reconnaissance Orbiter spacecraft. The blue dot indicates the approximate location of Opportunity. Image Credits: NASA/JPL-Caltech/MSSS.

This latest data transmission showed the rover's temperature to be about minus 20 degrees Fahrenheit (minus 29 degrees Celsius). One saving grace of dust storms is that they can actually limit the extreme temperature swings experienced on the Martian surface. The same swirling dust that blocks out sunlight also absorbs heat, raising the ambient temperature surrounding Opportunity.

Engineers will monitor the rover's power levels closely in the week to come. The rover needs to balance low levels of charge in its battery with sub-freezing temperatures. Its heaters are vitally important to keeping it alive, but also draw more power from the battery. Likewise, performing certain actions draws on battery power, but can actually expel energy and raise the rover's temperature.

The rover has proved hardier than expected by lasting nearly 15 years, despite being designed for a 90-day mission.

Science operations for NASA's Opportunity rover have been temporarily suspended as it waits out a growing dust storm on Mars.

NASA's Mars Reconnaissance Orbiter first detected the storm on Friday, June 1. As soon as the orbiter team saw how close the storm was to Opportunity, they notified the rover's team to begin preparing contingency plans.

In a matter of days, the storm had ballooned. It now spans more than 7 million square miles (18 million square kilometers) -- an area greater than North America -- and includes Opportunity's current location at Perseverance Valley. More importantly, the swirling dust has raised the atmospheric opacity, or "tau," in the valley in the past few days. This is comparable to an extremely smoggy day that blots out sunlight. The rover uses solar panels to provide power and to recharge its batteries.

Opportunity's power levels had dropped significantly by Wednesday, June 6, requiring the rover to shift to minimal operations.

Mars Exploration Rover. Image Credits: NASA/JPL-Caltech

This isn't Opportunity's first time hunkering down in bad weather: in 2007, a much larger storm covered the planet. That led to two weeks of minimal operations, including several days with no contact from the rover to save power. The project's management prepared for the possibility that Opportunity couldn't balance low levels of power with its energy-intensive survival heaters, which protect its batteries from Mars' extreme cold. It's not unlike running a car in the winter so that the cold doesn't sap its battery charge.  There is a risk to the rover if the storm persists for too long and Opportunity gets too cold while waiting for the skies to clear.

Ultimately, the storm subsided and Opportunity prevailed. The Martian cold is believed to have resulted in the loss of Spirit, Opportunity's twin in the Mars Exploration Rover mission, back in 2010. Despite this, both rovers have vastly exceeded expectations: they were only designed to last 90 days each. Opportunity is in its 15th year; the team has operated the rover for more than 50 times longer than originally planned.

Full dust storms like this one are not surprising, but are infrequent. They can crop up suddenly but last weeks, even months. During southern summer, sunlight warms dust particles, lifting them higher into the atmosphere and creating more wind. That wind kicks up yet more dust, creating a feedback loop that NASA scientists still seek to understand.

Mars Reconnaissance Orbiter and two other NASA spacecraft orbiting the Red Planet --Odyssey and MAVEN -- routinely support rovers on the ground.

For more information about the Mars Exploration Rovers, visit: https://mars.nasa.gov/mer/home/index.html

Related links:

Mars Reconnaissance Orbiter (MRO): https://mars.nasa.gov/mro/

Odyssey: https://mars.nasa.gov/odyssey/

MAVEN: https://mars.nasa.gov/maven/

Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/Andrew Good.

Greetings, Orbiter.ch

Artificial Intelligence, Cancer Therapy and Chemical Gardens Aboard SpaceX Dragon for Station Resupply Mission

SpaceX - SPX-15 CRS Mission patch.

June 10, 2018

A new batch of science is headed to the International Space Station aboard the SpaceX Dragon on the company’s 15th mission for commercial resupply services. The spacecraft will deliver science that studies the use of artificial intelligence, plant water use all over the planet, gut health in space, more efficient drug development and the formation of inorganic structures without the influence of Earth’s gravity. 

Take a look at five investigations headed to space on the latest SpaceX resupply:

Image Credit: NASA

As we travel farther into space, the need for artificial intelligence (AI) within a spacecraft increases.

Image Credit: NASA

Mobile Companion, a European Space Agency (ESA) investigation, explores the use of AI as a way to mitigate crew stress and workload during long-term spaceflight.

Image Credit: NASA

Plants regulate their temperature by releasing water through tiny pores on their leaves. If they have sufficient water they can maintain their temperature, but if water is insufficient their temperatures rise. This temperature rise can be measured with a sensor in space.

Image Credit: Northwestern University

ECOSTRESS measures the temperature of plants and uses that information to better understand how much water plants need and how they respond to stress.

Image Credit: Northwestern University

Spaceflight has an on impact many bodily systems. Rodent Research-7 takes a look at how the microgravity environment of space affects the community of microorganisms in the gastrointestinal tract, or microbiota.

The study also evaluates relationships between system changes, such as sleep-wake cycle disruption, and imbalance of microbial populations, to identify contributing factors and supporting development of countermeasures to protect astronaut health during long-term missions, as well as to improve the treatment of gastrointestinal, immune, metabolic and sleep disorders on Earth.

Image Credit: AngieX

Cardiovascular diseases and cancer are the leading causes of death in developed countries. Angiex Cancer Therapy examines whether microgravity-cultured endothelial cells represent a valid in vitro model to test effects of vascular-targeted agents on normal blood vessels.

Results may create a model system for designing safer drugs, targeting the vasculature of cancer tumors and helping pharmaceutical companies design safer vascular-targeted drugs.

Image Credit: Oliver Steinbock chemistry group at Florida State University

Chemical Gardens are structures that grow during the interaction of metal salt solutions with silicates, carbonates or other selected anions. Their growth characteristics and attractive final shapes form from a complex interplay between reaction-diffusion processes and self-organization.

Image Credit: Oliver Steinbock chemistry group at Florida State University

On Earth, gravity-induced flow due to buoyancy differences between the reactants complicates our understanding of the physics behind these chemical gardens. Conducting this experiment in a microgravity environment ensures diffusion-controlled growth and allows researchers a better assessment of initiation and evolution of these structures.

These investigations join hundreds of others currently happening aboard the orbiting laboratory (ISS).

Related links:

Mobile Companion: http://www.airbus.com/newsroom/press-releases/en/2018/02/hello--i-am-cimon-.html

ECOSTRESS: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1878

Rodent Research-7: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7425

Angiex Cancer Therapy: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7502

Chemical Gardens: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7678

European Space Agency (ESA): http://www.esa.int/ESA

Commercial Resupply: http://www.nasa.gov/mission_pages/station/structure/launch/index.html

Spot the Station: https://spotthestation.nasa.gov/

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

Images (mentioned), Text, Credits: NASA/Michael Johnson/JSC/International Space Station Program Science Office/Jenny Howard.

Greetings, Orbiter.ch

Neutron stars cast light on quark matter

CERN - European Organization for Nuclear Research logo.

June 10, 2018

Image above: Artist’s impression of the merger of two neutron stars (Image: University of Warwick/Mark Garlick).

Quark matter – an extremely dense phase of matter made up of subatomic particles called quarks – may exist at the heart of neutron stars. It can also be created for brief moments in particle colliders on Earth, such as CERN’s Large Hadron Collider. But the collective behaviour of quark matter isn’t easy to pin down. In a colloquium this week at CERN, Aleksi Kurkela from CERN’s Theory department and the University of Stavanger, Norway, explained how neutron-star data have allowed him and his colleagues to place tight bounds on the collective behaviour of this extreme form of matter.

Kurkela and colleagues used a neutron-star property deduced from the first observation by the LIGO and Virgo scientific collaborations of gravitational waves – ripples in the fabric of spacetime – emitted by the merger of two neutron stars. This property describes the stiffness of a star in response to stresses caused by the gravitational pull of a companion star, and is known technically as tidal deformability.

To describe the collective behaviour of quark matter, physicists generally employ equations of state, which relate the pressure of a state of matter to other state properties. But they have yet to come up with a unique equation of state for quark matter; they have derived only families of such equations. By plugging tidal-deformability values of the neutron stars observed by LIGO and Virgo into a derivation of a family of equations of state for neutron-star quark matter, Kurkela and colleagues were able to dramatically reduce the size of that equation family. Such a reduced family provides more stringent limits on the collective properties of quark matter, and more generally on nuclear matter at high densities, than were previously available.

Armed with these results, the researchers then flipped the problem around and used the quark-matter limits to deduce neutron-star properties. Using this approach, the team obtained the relationship between the radius and mass of a neutron star, and found that the maximum radius of a neutron star that is 1.4 times more massive than the Sun should be between about 10 and 14 km.

Want to find out more? Read the paper describing the research: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.120.172703

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 22 Member States.

For more information about European Organization for Nuclear Research (CERN), Visit: https://home.cern/

Image (mentioned), Text, Credits: CERN/Ana Lopes.

Best regards, Orbiter.ch