samedi 6 février 2016

GPM Satellite Examines Violent Thunderstorms








NASA / JAXA - Global Precipitation Measurement (GPM) logo.

Feb. 6, 2016

Severe weather moved through the southern U.S. on February 2 and 3, and NASA's Global Precipitation Measurement or GPM core satellite examined the violent thunderstorms.

On February 3, 2016 at 1851 UTC (1:51 p.m. EST) the GPM core observatory satellite flew over a line of storms extending from the Gulf coast of Florida through New York state. Tornadoes were spotted in Georgia and South Carolina within this area of violent weather. GPM's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR) instruments measured the precipitation within the area. As the satellite passed above, GPM's radar (DPR) found that one powerful thunderstorm in North Carolina was dropping rain at the extreme rate of 112.96 mm (4.4 inches) per hour.


Image above: On Feb. 3 at 1:51 p.m. EDT GPM found that one powerful thunderstorm in North Carolina was dropping rain at the extreme rate of 112.96 mm (4.4 inches) per hour. Image Credits: NASA/JAXA/SSAI, Hal Pierce.

At NASA's Goddard Space Flight Center in Greenbelt, Maryland, data collected by GPM's Radar (DPR Ku band) were used to create a 3-D cross-section through the precipitation within the line of violent thunderstorms.

Strong radar reflectivity values greater than 45dBZ (or decibel relative to Z) indicative of moderate to heavy rain, were returned to the GPM satellite from a few intense thundershowers. The dBz is a technical unit used in weather radar. The radar reflectivity (Z) of a cloud is dependent on the number and size of reflectors (like raindrops, snowflakes, hail or graupel). So, the higher the dBZ, the heavier the precipitation. The 45dBZ reading is equivalent to rain falling at 23.7 mm per hour (0.92 inches per hour).


Image above: On Feb. 3 at 1:51 p.m. EDT GPM found that one powerful thunderstorm in North Carolina was dropping rain at the extreme rate of 112.96 mm (4.4 inches) per hour. Image Credits: NASA/JAXA/SSAI, Hal Pierce.

NOAA's National Weather Service Storm Prediction Center (SPC) in Norman, Oklahoma reported at least 12 reports of tornadoes in parts of Alabama, Mississippi, Tennessee, South Carolina and Georgia over the severe weather outbreak over Tuesday and Wednesday. Feb. 2 and Feb. 3.

The SPC website indicated two tornadoes touched down on Feb. 3 in South Carolina and Georgia. SPC also noted many wind damage reports from this system.

NOAA SPC said that an EF0 tornado briefly touched down just north of Farmers Market in Lexington, South Carolina. The tornado's path ran for length 0.6 miles and was between 50 and 75 yards wide. Several cars damaged/destroyed in car storage lot.

In Liberty, Georgia, the Fort Stewart emergency management reported a tornado touched down near gate 7 in Fort Stewart around 5:01 p.m. EST and remained on the ground for approximately 10 minutes. In addition to these two tornadoes, SPC cited 20 wind reports.

On Feb. 4, 2016 the official Facebook page for the Fort Stewart Hunter Army Airfield stated "As the cleanup continues, large dumpsters will be located around the housing areas to make it easier to discard unwanted items and debris. Most roads are open with the exception of Greene Street which will remain closed for several days. Although most of the roads are opened, please be careful; cleanup crews are still working in and around those areas."

GPM core satellite. Image Credits: NASA/JAXA.

The Integrated Multi-satellitE Retrievals for GPM (IMERG) creates a merged precipitation product from the GPM constellation of satellites. These satellites include DMSPs from the U.S. Department of Defense, GCOM-W from the Japan Aerospace Exploration Agency (JAXA), Megha-Tropiques from the Centre National D’etudies Spatiales (CNES) and Indian Space Research Organization (ISRO), NOAA series from the National Oceanic and Atmospheric Administration (NOAA), Suomi-NPP from NOAA-NASA, and MetOps from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT).

All of the instruments (radiometers) onboard the constellation partners are inter-calibrated with information from the GPM Core Observatory’s GPM Microwave Imager (GMI) and DPR.

For more information about GPM, visit:  http://www.nasa.gov/gpm or http://pmm.nasa.gov

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

JAXA - Global Precipitation Measurement/Dual-frequency Precipitation Radar (GPM/DPR): http://global.jaxa.jp/projects/sat/gpm/

Related links:

SPC website: http://www.spc.noaa.gov/

Facebook page for the Fort Stewart Hunter Army Airfield: https://www.facebook.com/FortStewartHunterArmyAirfield

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Hal Pierce/Rob Gutro/Lynn Jenner.

Greetings, Orbiter.ch

Red or White? Healthy Humans Need Both












ISS - International Space Station patch.

Feb. 6, 2016

When it comes to wine, we can choose red or white depending on our tastes. With blood cells, however, we need both red and white in order to stay healthy and function well.

Spending time in space is known to cause changes in these blood cells. We don’t yet know for sure what causes this, but scientists suspect it may be due to how microgravity affects bone marrow. MARROW, a Canadian investigation recently launched to the International Space Station, will explore those effects. The results could lead to better mitigation strategies for spaceflight and crew return to Earth and gravity. The investigation also could advance understanding of how to minimize the effects of decreased activity in people with limited mobility or on bed rest on Earth.


Image above: Bone marrow showing an increase in fat after a period of immobility. Image Credits: Bone and Joint Research Laboratory, University of Ottawa.

Bone marrow contains cells that produce fat, erythrocytes (red blood cells) and leukocytes (white blood cells) within a confined and limited space. Previous research has shown that fat cells accumulate in marrow during life and more so during prolonged bed rest on Earth, an accumulation that comes at the expense of those blood-producing cells. 

Red blood cells deliver oxygen to all the cells of the body and a lack of sufficient red blood cells results in anemia, which can affect physical and mental functions necessary on a space mission. This condition has been documented in astronauts after return to Earth and is known as “space anemia.”

“If you have fewer red blood cells, you may be more easily fatigued and have decreased strength, cognitive ability, and heart function,” said principal investigator Dr. Guy Trudel, a professor at University of Ottawa in Canada. “Further, if inadequate red blood cell production occurs, crew members could be unable to mount an adequate response to a bleeding injury. They also would have difficulty performing duties upon returning to a gravity environment, such as landing on Mars or returning to Earth.”

White blood cells defend the body against infection and remove abnormal cells from the blood, thus helping to prevent cancer. That function is especially important for astronauts, who are exposed to increased radiation in space.


Image above: Normal bone marrow. Image Credits: Bone and Joint Research Laboratory, University of Ottawa.

The investigation, funded by the Canadian Space Agency, will measure bone marrow fat pre- and post-flight using magnetic resonance. Researchers will analyze red and white blood cell function during flight as well as pre- and post-flight. They will measure red blood cell function by analyzing the breath of crew members, since the concentration of carbon monoxide in the breath indicates the extent of breakdown of red blood cells.

For white blood cell function, investigators will analyze genetic expression, explained co-investigator Dr. Odette Laneuville, also at the University of Ottawa, taking multiple profiles of gene expression over time. This will help identify specific genes that change in microgravity.

“One important component of the investigation is looking at reversibility, whether bone marrow composition returns to preflight levels and blood cell production recovers once crews return to Earth or land on another planet,” said Trudel. “The results from this investigation could guide the search for specific countermeasures, such as exercise, or pharmacological or genetic treatments, as well as preventative interventions.”


Image above: ESA astronaut Tim Peake tweeted picture of his first blood draw completed in space. The sample was taken as part of the MARROW investigation. Image Credit: NASA.

Accelerated fat accumulation was identified in previous research that measured fat in blood-producing bones during a specific form of bedrest used to simulate microgravity. Lack of physical activity – and therefore lack of mechanical stimulation of bone – could somehow flip a switch in stem cells that can become either bone or fat, pushing them toward becoming the latter.

On Earth, fat accumulation in bone marrow and changes in blood cell function are associated with normal aging, conditions such as paralysis and osteoporosis, and prolonged periods of bed rest or limited mobility. So future space explorers and those of us on the ground will benefit from learning more about how to keep both red and white blood cells functioning well.

Related links:

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

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

MARROW - Canadian investigation: http://www.nasa.gov/mission_pages/station/research/experiments/1931.html

University of Ottawa: http://www.uottawa.ca/en

Images (mentioned), Text, Credits: NASA Johnson Space Center/Melissa Gaskill/Kristine Rainey.

Best regards, Orbiter.ch

vendredi 5 février 2016

Atlas V Delivers GPS IIF-12 for the US Air Force















ULA - Atlas V / GPS IIF-12 launch poster.


Feb. 5, 2016

United Launch Alliance Successfully Launches GPS IIF-12 Satellite for U.S. Air Force. The launch marks ULA’s first launch for 2016 and the final launch of the GPS IIF block.

Atlas V carrying GPS IIF-12 liftoff

United Launch Alliance (ULA) successfully launched its first mission of the year with an Atlas V rocket carrying the Global Positioning System (GPS) IIF-12 satellite for the U.S. Air Force. The rocket lifted off from Space Launch Complex-41 on Feb. 5 at 8:38 a.m. EST.

GPS IIF-12 is the final satellite in the IIF-block of satellites, which are the next-generation GPS satellites that incorporate numerous improvements to provide greater accuracy, increased signals and enhanced performance for users. This mission was ULA’s 104th successful launch since the company was formed in December 2006.

video
Atlas V GPS IIF-12 Launch Highlights

“Congratulations to the ULA, Boeing and Air Force teams on the successful launch of GPS IIF-12.  We began launching the IIF satellites in May 2010 and have appreciated the outstanding teamwork of everyone involved as we have worked together to deliver all 12 IIF satellites. This system provides incredible capabilities to our women and men in uniform while enabling so many technologies that impact all of our daily lives. We are proud to be GPS’s ride to space,” said Laura Maginnis, ULA vice president, Custom Services.

The mission was launched aboard an Atlas V Evolved Expendable Launch Vehicle (EELV) 401 configuration vehicle, which includes a 4-meter diameter payload fairing. The Atlas booster for this mission was powered by the RD AMROSS RD-180 engine, and the Centaur upper stage was powered by the Aerojet Rocketdyne RL10C-1 engine.

Today’s flight utilizes a newly designed suite of avionics, flight software and ground systems. This upgraded command and control system was designed to reduce cost and improve reliability.

ULA's next launch is the Delta IV NROL-45 mission for the National Reconnaissance Office, scheduled for Feb. 10 from Space Launch Complex-6 from Vandenberg Air Force Base, California.

GPS IIF satellite

The EELV program was established by the U.S. Air Force to provide assured access to space for Department of Defense and other government payloads. The commercially developed EELV program supports the full range of government mission requirements, while delivering on schedule and providing significant cost savings over the heritage launch systems.

With more than a century of combined heritage, United Launch Alliance is the nation’s most experienced and reliable launch service provider. ULA has successfully delivered more than 100 satellites to orbit that provide critical capabilities for troops in the field, aid meteorologists in tracking severe weather, enable personal device-based GPS navigation and unlock the mysteries of our solar system.

For more information on ULA, visit the ULA website at http://www.ulalaunch.com.

Join the conversation at http://www.facebook.com/ulalaunch, http://twitter.com/ulalaunch and http://instagram.com/ulalaunch.

Images, Video, Text, Credits: United Launch Alliance (ULA)/Günter Space Page.

Greetings, Orbiter.ch

Apollo Astronaut Edgar Mitchell Dies at Age 85











NASA logo.

Feb. 5, 2016

Astronaut Edgar Mitchell, lunar module pilot on Apollo 14, passed away Thursday in West Palm Beach, Fla., on the eve of the 45th anniversary of his lunar landing.

Mitchell joined Apollo 14 commander Alan Shephard, Jr., the first American in space, in the lunar module Antares, which touched down Feb. 5, 1971, in the Fra Mauro highlands. Shepard and Mitchell were assigned to traverse the lunar surface to deploy scientific instruments and perform a communications test on the surface, as well as photograph the lunar surface and any deep space phenomena. It was Mitchell’s only spaceflight.


Image above: Astronaut Edgar D. Mitchell, Apollo 14 lunar module pilot stands by the deployed U.S. flag on the lunar surface during the early moments of the mission's first spacewalk. He was photographed by astronaut Alan B. Shepard Jr., mission commander. While astronauts Shepard and Mitchell descended in the Lunar Module "Antares" to explore the Fra Mauro region of the moon, astronaut Stuart A. Roosa, command module pilot, remained with the Command and Service Module "Kitty Hawk" in lunar orbit. Image Credit: NASA.

Mitchell and Shephard set mission records for the time of the longest distance traversed on the lunar surface; the largest payload returned from lunar surface; and the longest lunar stay time (33 hours). They were also the first to transmit color TV from the lunar surface. Mitchell helped collect 94 pounds of lunar rock and soil samples that were distributed across 187 scientific teams in the United States and 14 other countries for analysis.

"On behalf of the entire NASA family, I would like to express my condolences to the family and friends of NASA astronaut Edgar Mitchell," NASA Administrator Charles Bolden said in a statement. "As a member of the Apollo 14 crew, Edgar is one of only 12 men to walk on the moon and he helped to change how we view our place in the universe. "


Image above: Apollo astronaut Edgar Mitchell in front of a graphic of the mission patch. Image Credit: NASA.

Mitchell was drawn to the spaceflight by President Kennedy's call to send astronauts to the moon. "After Kennedy announced the moon program, that's what I wanted, because it was the bear going over the mountain to see what he could see, and what could you learn, and I've been devoted to that, to exploration, education, and discovery since my earliest years, and that's what kept me going," Mitchell said in 1997 interview for NASA's oral history program.

"To me, that (spaceflight) was the culmination of my being, and what can I learn from this? What is it we are learning? That's important, because I think what we're trying to do is discover ourselves and our place in the cosmos, and we don't know. We're still looking for that."

In his book "The Way of the Explorer", Mitchell wrote, "There was a sense that our presence as space travelers, and the existence of the universe itself, was not accidental but that there was an intelligent process at work.”

Mitchell retired from NASA and the U.S. Navy and founded the Institute of Noetic Sciences in 1973, organized to sponsor research in the nature of consciousness. In 1984, he co-founded the Association of Space Explorers, and international organization for all who “share experience of space travel.” The mission of this organization is to provide a new understanding of the human condition resulting from the epoch of space exploration.

Edgar D. Mitchell was born Sept. 17, 1930 in Hereford, Texas, and considered Artesia, N.M., his hometown. He graduated with a B.S. in Industrial Management from Carnegie Mellon in 1952, a B.S. in Aeronautics from the U.S. Naval Postgraduate School in 1961 and a Doctorate in Aeronautics and Astronautics from the Massachusetts Institute of Technology in 1964.  NASA selected Mitchell as an astronaut in 1966. He served on the support crew for Apollo 9 and as backup lunar module pilot for Apollo 10. He worked in the lunar module simulator at the Johnson Space Center during Apollo 13, developing procedures that would bring the crew of that crippled spacecraft home.

NASA images of Edgar Mitchell: http://www.nasa.gov/content/edgar-mitchell-images

NASA Oral History Project interview with Edgar Mitchell: http://www.jsc.nasa.gov/history/oral_histories/MitchellED/MitchellED_9-3-97.htm

NASA Administrator Charles Bolden said in a statement: http://www.nasa.gov/press-release/nasa-administrator-remembers-apollo-era-astronaut-edgar-mitchell

Related links:

Apollo: http://www.nasa.gov/mission_pages/apollo/index.html

NASA History: http://www.nasa.gov/topics/history/index.html

Images (mentioned), Text, Credits: NASA/Brian Dunbar.

R.I.P.; Orbiter.ch

Hubble Views Merging Galaxies in Eridanus











NASA - Hubble Space Telescope patch.

Feb. 5, 2016


This image, taken by the NASA/ESA Hubble Space Telescope, shows a peculiar galaxy known as NGC 1487, lying about 30 million light-years away in the southern constellation of Eridanus.

Rather than viewing it as a celestial object, it is actually better to think of this as an event. Here, we are witnessing two or more galaxies in the act of merging together to form a single new galaxy. Each galaxy has lost almost all traces of its original appearance, as stars and gas have been thrown by gravity in an elaborate cosmic whirl.

Unless one is very much bigger than the other, galaxies are always disrupted by the violence of the merging process. As a result, it is very difficult to determine precisely what the original galaxies looked like and, indeed, how many of them there were. In this case, it is possible that we are seeing the merger of several dwarf galaxies that were previously clumped together in a small group.

Although older yellow and red stars can be seen in the outer regions of the new galaxy, its appearance is dominated by large areas of bright blue stars, illuminating the patches of gas that gave them life. This burst of star formation may well have been triggered by the merger.

video
Hubble and the sunrise over Earth

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency (ESA). 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.

For images and more information about Hubble, visit:

    http://www.nasa.gov/hubble
    http://hubblesite.org/
    http://www.spacetelescope.org/

Image, Video, Credits: ESA/Hubble & NASA, Acknowledgement: Judy Schmidt/Text Credits: European Space Agency/ Ashley Morrow.

Best regards, Orbiter.ch

jeudi 4 février 2016

Pluto’s Mysterious, Floating Hills












NASA - New Horizons Mission logo.

Feb. 4, 2016


Image above: Hills of water ice on Pluto ‘float’ in a sea of frozen nitrogen and move over time like icebergs in Earth’s Arctic Ocean—another example of Pluto’s fascinating geological activity. Image Credits: NASA/JHUAPL/SwRI.

The nitrogen ice glaciers on Pluto appear to carry an intriguing cargo: numerous, isolated hills that may be fragments of water ice from Pluto’s surrounding uplands. These hills individually measure one to several miles or kilometers across, according to images and data from NASA’s New Horizons mission.

The hills, which are in the vast ice plain informally named Sputnik Planum within Pluto’s ‘heart,’ are likely miniature versions of the larger, jumbled mountains on Sputnik Planum’s western border. They are yet another example of Pluto’s fascinating and abundant geological activity.

Because water ice is less dense than nitrogen-dominated ice, scientists believe these water ice hills are floating in a sea of frozen nitrogen and move over time like icebergs in Earth’s Arctic Ocean. The hills are likely fragments of the rugged uplands that have broken away and are being carried by the nitrogen glaciers into Sputnik Planum. ‘Chains’ of the drifting hills are formed along the flow paths of the glaciers. When the hills enter the cellular terrain of central Sputnik Planum, they become subject to the convective motions of the nitrogen ice, and are pushed to the edges of the cells, where the hills cluster in groups reaching up to 12 miles (20 kilometers) across.

At the northern end of the image, the feature informally named Challenger Colles – honoring the crew of the lost space shuttle Challenger – appears to be an especially large accumulation of these hills, measuring 37 by 22 miles (60 by 35 kilometers). This feature is located near the boundary with the uplands, away from the cellular terrain, and may represent a location where hills have been ‘beached’ due to the nitrogen ice being especially shallow.


Image above: The hills, which are in the vast ice plain informally named Sputnik Planum within Pluto’s ‘heart,’ are likely miniature versions of the larger, jumbled mountains on Sputnik Planum’s western border. They are yet another example of Pluto’s fascinating and abundant geological activity. Image Credits: NASA/JHUAPL/SwRI.

The image above shows the inset in context next to a larger view that covers most of Pluto’s encounter hemisphere. The inset was obtained by New Horizons’ Multispectral Visible Imaging Camera (MVIC) instrument. North is up; illumination is from the top-left of the image. The image resolution is about 1050 feet (320 meters) per pixel. The image measures a little over 300 miles (almost 500 kilometers) long and about 210 miles (340 kilometers) wide. It was obtained at a range of approximately 9,950 miles (16,000 kilometers) from Pluto, about 12 minutes before New Horizons’ closest approach to Pluto on July 14, 2015.

For more information about New Horizons, visit:
http://www.nasa.gov/mission_pages/newhorizons/main/index.html

Images (mentioned), Text, Credits: NASA/Tricia Talbert.

Best regards, Orbiter.ch

First locks released from LISA Pathfinder's cubes












ESA - LISA Pathfinder Mission patch.

4 February 2016

Yesterday, the lock fingers that kept the two test masses on LISA Pathfinder secure during the launch and cruise phase were successfully unlocked. As planned, the two cubes are still attached to the spacecraft via an additional mechanism that will hold them in place until mid February, as the teams carry on with the spacecraft and payload commissioning.

Tests on LISA Pathfinder are proceeding on schedule. The spacecraft completed its six-week journey in space, reaching its operational location in orbit around the Lagrange point L1 on 22 January 2016.

With the spacecraft settling into its new home, teams from ESA, Airbus Defence and Space (the prime contractor) and the institutes that provided the payload hardware continue to perform tests on the various systems, subsystems and instruments in preparation for when science operations will begin on 1 March.


Image above: Artistic view of LISA Pathfinder in space. Image Credits: ESA/C.Carreau.

At the centre of the spacecraft is the LISA Technology Package, which houses the two test masses that will be put in the most precise free-fall motion ever obtained in space. The position and attitude of these two identical gold-platinum cubes is monitored by a laser interferometer to estimate how much their motion is affected by other forces beyond gravity.

On 13 January, the laser was the first element of the science payload to be switched on, and preliminary measurements indicate that its performance is exceptionally good.

But it will be another few weeks before everything is ready to begin the science phase of this mission.

“During operations on ground, launch and cruise, each cube was held in position by eight launch lock fingers pressing the cube's eight corners,” explains César García Marirrodriga, ESA's LISA Pathfinder project manager.

“Today, we successfully pulled back the lock fingers, handing the cubes over to the Grabbing, Positioning and Release Mechanism (GPRM) – these are additional mechanical elements that are softly holding the two opposite faces of each cube,” he adds.


Images above: Up: One of LISA Pathfinder's two test masses: the hemispherical protrusions in the four corners are where the launch lock fingers of the caging mechanism hold the test mass, and the inverted pyramid in the centre is where the GPRM grabs the cube. Down: Assembly of one of the Inertial Sensor Heads for the LISA Technology Package (LTP). Three launch lock fingers are visible as the vertical elements on top of the electrode housing. Images Credits: CGS SpA.

The release of the test masses is a crucial procedure for operating the mission, so it was designed in two steps.

First, the launch lock fingers are retracted, simultaneously opening a gate valve to vent the interior of the inertial sensors and pump residual gas molecules out to space. Recreating a high vacuum environment around the test masses will take a couple of weeks. Second, the GPRM will be retracted from one of the cubes on 15 February, and on the following day from the other one. When the GPRM is retracted, the test masses will no longer be in mechanical contact with the spacecraft, freely floating inside their housing.

The cubes measure 46 mm across and are about 4 mm away from the walls of their respective housing. In order to place them correctly, the mechanism must release each cube with a positional accuracy of approximately 200 μm with respect to the geometrical centre in all three directions. To avoid reaching any of the walls, the masses must be released with a velocity of less than 5 μm/s, or 18 mm/h, meaning that it would take them about a quarter of an hour to cover the space separating them from the surrounding walls.


Image above: The LISA Technology Package core assembly, hosting the two test masses and, between them, the optical bench interferometer. Image Credits: ESA/ATG medialab.

“We are excited about the final test mass release, because the minute forces and velocities involved could not be fully tested on ground: it was not physically possible in the presence of Earth's gravity,” says Hans Rozemeijer, LISA Pathfinder payload engineer.

“In space missions we normally test what we will fly, and then we fly what we tested, but sometimes the ground conditions simply do not let us fulfil this paradigm,” he adds.

Immediately after the GPRM is released, the teams will apply electrostatic forces to the cubes using the electrodes in their housings to move them and make them follow the spacecraft. Over the following days, they will gradually reduce the intensity of the electrostatic force until eventually no force is applied to the masses, and the spacecraft will start moving around one of the free-falling cubes. This is the nominal operating mode for the science phase of LISA Pathfinder, and it will be first activated on 23 February.

For more information about LISA Pathfinder, visit: http://sci.esa.int/lisa-pathfinder/

LISA Pathfinder operations:
http://www.esa.int/Our_Activities/Operations/LISA_Pathfinder_operations

Images (mentioned), Text, Credits: ESA/César García Marirrodriga/Hans Rozemeijer/Paul McNamara.

Greetings, Orbiter.ch

Veteran Astronaut Kevin Ford Departs NASA











NASA logo.

Feb. 4, 2016

After two spaceflights and more than 15 years with NASA, Kevin Ford left the space agency on Jan. 29. He spent more than 33 years in government service.

“Kevin has served the office in a number of ways over the years, and we will certainly miss him,” said Chris Cassidy, chief of the Astronaut Office at NASA’s Johnson Space Center. “I had the pleasure of serving as his backup for his space station mission, and consequently spent many weeks in Russia and Kazakhstan with him. Personally, I will miss his sense of humor and special insight into technical issues. He is a great American and true friend. We all wish him well and have no doubt that he will bring a great deal of valuable experience to all of his future endeavors.”

Astronaut Kevin Ford

NASA selected Ford as an astronaut in 2000. After completing initial training, Ford served in various technical positions, including the director of operations in Star City, Russia, for one year and Capcom for six space shuttle missions. He served as space shuttle pilot for the STS-128 mission in 2009, helping to deliver more than 15,000 pounds of science and storage racks to the International Space Station. He then returned to the station aboard Soyuz TMA-06M in 2012, serving as flight engineer for Expedition 33, and commander on Expedition 34. Ford spent a total of 157 days and 13 hours in space.

Ford was born in Portland, Indiana, and considers Montpelier, Indiana, his hometown. He holds degrees in aerospace engineering, international relations and astronautical engineering from the University of Notre Dame, Troy State University, the University of Florida and the Air Force Institute of Technology. A retired U.S. Air Force colonel, he has accumulated more than 5,000 flying hours, and holds FAA instructor ratings for airplanes and gliders, a commercial rating for helicopters and a private rating for hot air balloons.

Ford’s complete biography is available at: http://www.jsc.nasa.gov/Bios/htmlbios/ford-ka.html

Image, Text, Credits: NASA/JSC/Brandi Dean.

Greetings, Orbiter.ch

Inside Rosetta’s comet












ESA - Rosetta Mission patch.

4 February 2016

There are no large caverns inside Comet 67P/Churyumov-Gerasimenko. ESA’s Rosetta mission has made measurements that clearly demonstrate this, solving a long-standing mystery.

Comets are the icy remnants left over from the formation of the planets 4.6 billion years ago. A total of eight comets have now been visited by spacecraft and, thanks to these missions, we have built up a picture of the basic properties of these cosmic time capsules. While some questions have been answered, others have been raised.

Comet 67P/Churyumov-Gerasimenko

Comets are known to be a mixture of dust and ice, and if fully compact, they would be heavier than water. However, previous measurements have shown that some of them have extremely low densities, much lower than that of water ice. The low density implies that comets must be highly porous.

But is the porosity because of huge empty caves in the comet’s interior or it is a more homogeneous low-density structure?

In a new study, published in this week’s issue of the journal Nature, a team led by Martin Pätzold, from Rheinische Institut für Umweltforschung an der Universität zu Köln, Germany, have shown that Comet 67P/Churyumov-Gerasimenko is also a low-density object, but they have also been able to rule out a cavernous interior.

This result is consistent with earlier results from Rosetta’s CONSERT radar experiment showing that the double-lobed comet’s ‘head’ is fairly homogenous on spatial scales of a few tens of metres.

The most reasonable explanation then is that the comet’s porosity must be an intrinsic property of dust particles mixed with the ice that make up the interior. In fact, earlier spacecraft measurements had shown that comet dust is typically not a compacted solid, but rather a ‘fluffy’ aggregate, giving the dust particles high porosity and low density, and Rosetta’s COSIMA and GIADA instruments have shown that the same kinds of dust grains are also found at 67P/Churyumov-Gerasimenko.

New Norcia station

Pätzold’s team made their discovery by using the Radio Science Experiment (RSI) to study the way the Rosetta orbiter is pulled by the gravity of the comet, which is generated by its mass.

The effect of the gravity on the movement of Rosetta is measured by changes in the frequency of the spacecraft’s signals when they are received at Earth. It is a manifestation of the Doppler effect, produced whenever there is movement between a source and an observer, and is the same effect that causes emergency vehicle sirens to change pitch as they pass by.

In this case, Rosetta was being pulled by the gravity of the comet, which changed the frequency of the radio link to Earth. ESA’s 35-metre antenna at the New Norcia ground station in Australia is used to communicate with Rosetta during routine operations. The variations in the signals it received were analysed to give a picture of the gravity field across the comet. Large internal caverns would have been noticeable by a tell-tale drop in acceleration.

ESA’s Rosetta mission is the first to perform this difficult measurement for a comet.

“Newton’s law of gravity tells us that the Rosetta spacecraft is basically pulled by everything,” says Martin Pätzold, the principal investigator of the RSI experiment.

“In practical terms, this means that we had to remove the influence of the Sun, all the planets – from giant Jupiter to the dwarf planets – as well as large asteroids in the inner asteroid belt, on Rosetta’s motion, to leave just the influence of the comet. Thankfully, these effects are well understood and this is a standard procedure nowadays for spacecraft operations.”

Next, the pressure of the solar radiation and the comet’s escaping gas tail has to be subtracted. Both of these ‘blow’ the spacecraft off course. In this case, Rosetta’s ROSINA instrument is extremely helpful as it measures the gas that is streaming past the spacecraft. This allowed Pätzold and his colleagues to calculate and remove those effects too.

Whatever motion is left is due to the comet’s mass. For Comet 67P/Churyumov-Gerasimenko, this gives a mass slightly less than 10 billion tonnes. Images from the OSIRIS camera have been used to develop models of the comet’s shape and these give the volume as around 18.7 km3, meaning that the density is 533 kg/m3.

Extracting the details of the interior was only possible through a piece of cosmic good luck.

Given the lack of knowledge of the comet’s activity, a cautious approach trajectory had been designed to ensure the spacecraft's safety. Even in the best scenario, this would bring Rosetta no closer than 10 km.


Image above: OSIRIS Image of the Day 2016-01-30 T 10:43:12.382 (UTC). Image Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

Unfortunately, prior to 2014, the RSI team predicted that they needed to get closer than 10 km to measure the internal distribution of the comet. This was based on ground-based observations that suggested the comet was round in shape. At 10 km and above, only the total mass would be measurable.

Then the comet’s strange shape was revealed as Rosetta drew nearer. Luckily for RSI, the double-lobed structure meant that the differences in the gravity field would be much more pronounced, and therefore easier to measure from far away.

“We were already seeing variations in the gravity field from 30 km away,” says Pätzold.

When Rosetta did achieve a 10 km orbit, RSI was able to gather detailed measurements. This is what has given them such high confidence in their results, and it could get even better.

In September, Rosetta will be guided to a controlled impact on the surface of the comet. The manoeuvre will provide a unique challenge for the flight dynamics specialists at ESA’s European Space Operations Centre (ESOC) in Darmstadt, Germany. As Rosetta gets nearer and nearer the complex gravity field of the comet will make navigating harder and harder. But for RSI, its measurements will increase in precision. This could allow the team to check for caverns just a few hundred metres across.

Notes for Editors:

“A homogeneous nucleus for Comet 67P/ Churyumov–Gerasimenko from its gravity field,” by M. Pätzold et al. is published in the journal Nature: http://www.nature.com/nature/journal/v530/n7588/full/nature16535.html

Related links:

For more information about Rosetta mission, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta in depth:http://sci.esa.int/rosetta

Rosetta at Astrium: http://www.astrium.eads.net/en/programme/rosetta-1go.html

Rosetta at DLR: http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10394/

Ground-based comet observation campaign: http://www.rosetta-campaign.net/home

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Images, Text, Credits: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0.

Best regards, Orbiter.ch

Russian spacewalk marks end of ESA’s exposed space chemistry












ESA - Principia Mission patch.

4 February 2016

Yuri and Sergei before spacewalk

ESA’s Expose facility was retrieved today from outside the International Space Station by cosmonauts Yuri Malenchenko and Sergei Volkov, who were completing a spacewalk to place new experiments on the outpost’s hull. 

Expose is a series of chemistry laboratories that place samples in the harsh environment of space unprotected. Subjected to vacuum, radiation, temperature differences and the full blast of our Sun’s energy, 46 species of small organisms and over 150 organic compounds have returned after spending 18 months bolted to the Zvezda module.

Expose-R2

Having travelled around the world over 8500 times, researchers are eager to see how the organisms and chemical samples have endured their trip. Inspecting the organisms back on Earth could help in the search for alien life while chemical analysis will help researchers understand how molecules react to space travel.

Astrochemistry on the Space Station

The building blocks of life on Earth, organic chemicals, could have landed on our planet via meteorites after travelling millions of years through space. Most chemical compounds are not stable but over time break down to form different molecules.

The chemistry experiment that is part of the Expose facility, called Photochemistry on the Space Station (PSS), is investigating which chemicals we find on Earth could have come from space.

Yuri and Sergei spacewalk

Lead investigator Hervé Cottin, from the University of Paris-Est Créteil, explains: “Expose is nothing less than a little chemistry box to help us better understand chemical reactions in space. If a molecule survives 18 months in space then it could come to Earth from space.

“If a molecule has changed after its 18-month voyage then we know that space travel filters our observations on Earth and a chemical might have formed from a different configuration.”

This research has implications for data gathered from other space missions such as comet-chaser Rosetta or Titan probe Huygens, or the upcoming ExoMars mission. These spacecraft and rover provide researchers with information on the chemicals they detect as they explore our Solar System. On those distant worlds, solar radiation is not filtered by our atmosphere, so their chemistries could be quite different to that on our planet.

Retrieving Expose-R2

Of the 150 samples are on Expose-R2, half are in direct sunlight and another half were protected from the Sun. Another 225 samples have been kept on Earth in varying conditions as a control.

Thirty researchers from 11 laboratories in the Netherlands, Italy, France and USA started on this project in 2009, and the samples will return to Earth on a  Soyuz spacecraft soon for analysis.

Related Links:

First results from Expose-E Mission reported in Astrobiology Journal: http://www.liebertpub.com/global/pressrelease/first-results-of-deep-space-experiments-from-expose-e-mission-reported-in-astrobiology-journal/1057/

Read the Astrobiology Journal special collection on Expose-E: http://online.liebertpub.com/toc/ast/12/5

Experiment archive: http://eea.spaceflight.esa.int/

Principia mission: http://www.esa.int/Our_Activities/Human_Spaceflight/Principia

Principia in UK: https://principia.org.uk/

University of Paris-Est Créteil: http://www.en.u-pec.fr/

The search for alien life: http://www.esa.int/Our_Activities/Human_Spaceflight/Research/Space_Kombucha_in_the_search_for_life_and_its_origin

Images, Text, Credits: ESA/NASA/ROSCOSMOS.

Greetings, Orbiter.ch

mercredi 3 février 2016

NASA’s Juno Spacecraft Burns for Jupiter












NASA - JUNO Mission logo.

Feb. 3, 2016


Image above: Launching from Earth in 2011, the Juno spacecraft will arrive at Jupiter in 2016 to study the giant planet from an elliptical, polar orbit. Juno will repeatedly dive between the planet and its intense belts of charged particle radiation, coming only 5,000 kilometers (about 3,000 miles) from the cloud tops at closest approach. Image Credits: NASA/JPL-Caltech.

NASA's solar-powered Juno spacecraft successfully executed a maneuver to adjust its flight path today, Feb. 3. The maneuver refined the spacecraft’s trajectory, helping set the stage for Juno's arrival at the solar system’s largest planetary inhabitant five months and a day from now.

"This is the first of two trajectory adjustments that fine tune Juno’s orbit around the sun, perfecting our rendezvous with Jupiter on July 4th at 8:18 p.m. PDT [11:18 p.m. EDT]," said Scott Bolton, Juno principal investigator at the Southwest Research Institute in San Antonio.

The maneuver began at 10:38 a.m. PST (1:38 p.m. EST). The Juno spacecraft's thrusters fired for 35 minutes, consumed about 1.2 pounds (.56 kilograms) of fuel, and changed the spacecraft's speed by 1 foot (0.31 meters), per second. At the time of the maneuver, Juno was about 51 million miles (82 million kilometers) from Jupiter and approximately 425 million miles (684 million kilometers) from Earth. The next trajectory correction maneuver is scheduled for May 31.


Graphic above: This graphic shows how NASA’s Juno mission to Jupiter became the most distant solar-powered explorer and influenced the future of space exploration powered by the sun. Graphic Credits: NASA/JPL-Caltech.

Juno was launched on Aug. 5, 2011. The spacecraft will orbit the Jovian world 33 times, skimming to within 3,100 miles (5,000 kilometers) above the planet's cloud tops every 14 days. During the flybys, Juno will probe beneath the obscuring cloud cover of Jupiter and study its aurorae to learn more about the planet's origins, structure, atmosphere and magnetosphere.

Juno's name comes from Greek and Roman mythology. The god Jupiter drew a veil of clouds around himself to hide his mischief, and his wife -- the goddess Juno -- was able to peer through the clouds and reveal Jupiter's true nature.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA's New Frontiers Program, which is managed at NASA's Marshall Space Flight Center in Huntsville, Alabama, for NASA's Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. The California Institute of Technology in Pasadena manages JPL for NASA.

Related article:

NASA's Juno Spacecraft Breaks Solar Power Distance Record:
http://orbiterchspacenews.blogspot.ch/2016/01/nasas-juno-spacecraft-breaks-solar.html

For more information about Juno visit these sites:

http://www.nasa.gov/juno

http://missionjuno.swri.edu

Images (mentioned), Text, Credits: NASA/Tony Greicius/JPL/DC Agle/Lockheed Martin Space Systems/Gary Napier/Southwest Research Institute/Deb Schmid.

Greetings, Orbiter.ch

Second Spacewalk of Year Complete













ISS - Expedition 46 Mission patch / ROSCOSMOS - Russian Cosmonaut patch.

Feb. 3, 2016

video
Russian Cosmonauts Conduct Spacewalk Outside the International Space Station

Video above: Outside the International Space Station, Expedition 46 Flight Engineers Yuri Malenchenko and Sergey Volkov of Roscosmos conducted a spacewalk Feb. 3 to install experiment packages on the hull of the Russian segment of the complex and retrieve other experiments that have been gathering data for several months. It was the 193rd spacewalk in support of space station assembly and maintenance, the sixth in Malenchenko’s career and the fourth for Volkov. Video Credit: NASA TV.


Image above: Today’s spacewalkers are cosmonauts Yuri Malenchenko and Sergey Volkov. Image Credit: NASA TV.

Expedition 46 Flight Engineers Yuri Malenchenko and Sergey Volkov of Roscosmos successfully concluded their spacewalk at 12:40 p.m. EST.

The cosmonauts installed and retrieved a number of science experiments and conducted extensive photography of the external surfaces of the Russian segment of the International Space Station.


Image above: Spacewalkers Yuri Malenchenko and Sergey Volkov work outside the Pirs docking compartment on gear installation and science experiments. Image Credit: NASA TV.

The 4 hour and 45 minute spacewalk was the sixth for Malenchenko and the fourth for Volkov. Space station crew members have conducted 193 spacewalks in support of assembly and maintenance of the orbiting laboratory. Spacewalkers have now spent a total of 1,204 hours and 48 minutes working outside the station.

For more information about the International Space Station and its crew, visit: http://www.nasa.gov/station

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

Images (mentioned), Video (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.ch

Small Asteroid to Pass Close to Earth March 5










Asteroid Watch logo.

Feb. 3, 2016

A small asteroid that two years ago flew past Earth at a comfortable distance of about 1.3 million miles (2 million kilometers) will safely fly by our planet again in a few weeks, though this time it may be much closer.

During the upcoming March 5 flyby, asteroid 2013 TX68 could fly past Earth as far out as 9 million miles (14 million kilometers) or as close as 11,000 miles (17,000 kilometers). The variation in possible closest approach distances is due to the wide range of possible trajectories for this object, since it was tracked for only a short time after discovery.


Image above: Graphic indicates the cloud of possible locations asteroid 2013 TX68 will be in at the time of its closest approach to Earth during its safe flyby of our planet on March 5. The nearest point in this graphic above Earth represents the very closest the asteroid could possibly come -- which is no closer than 11,000 miles. On the far left, a point indicates the very farthest out the asteroid could be when it flies past -- about 9 million miles. With additional observations, scientists can typically recalculate and refine the known orbit of an asteroid, reducing the size and quantity of the cloud of potential locations during time of closest approach. Image Credits: NASA/JPL-Caltech.

Scientists at NASA's Center for NEO Studies (CNEOS) at the Jet Propulsion Laboratory in Pasadena, California, have determined there is no possibility that this object could impact Earth during the flyby next month. But they have identified an extremely remote chance that this small asteroid could impact on Sep. 28, 2017, with odds of no more than 1-in-250-million. Flybys in 2046 and 2097 have an even lower probability of impact.

"The possibilities of collision on any of the three future flyby dates are far too small to be of any real concern," said Paul Chodas, manager of CNEOS. "I fully expect any future observations to reduce the probability even more."

Asteroid 2013 TX68 is estimated to be about 100 feet (30 meters) in diameter. By comparison, the asteroid that broke up in the atmosphere over Chelyabinsk, Russia, three years ago was approximately 65 feet (20 meters) wide. If an asteroid the size of 2013 TX68 were to enter Earth's atmosphere, it would likely produce an air burst with about twice the energy of the Chelyabinsk event.

Artist's view of asteroids passing near Earth

The asteroid was discovered by the NASA-funded Catalina Sky Survey on Oct. 6, 2013, as it approached Earth on the nighttime side. After three days of tracking, the asteroid passed into the daytime sky and could no longer be observed. Because it was not tracked for very long, scientists cannot predict its precise orbit around the sun, but they do know that it cannot impact Earth during its flyby next month.

"This asteroid’s orbit is quite uncertain, and it will be hard to predict where to look for it," said Chodas. "There is a chance that the asteroid will be picked up by our asteroid search telescopes when it safely flies past us next month, providing us with data to more precisely define its orbit around the sun."

For regular updates on passing asteroids, NASA has a list of the next five close approaches to Earth; it links to the CNEOS website with a complete list of recent and upcoming close approaches, as well as all other data on the orbits of known NEOs, so scientists and members of the media and public can track information on known objects.

Related link:

CNEOS website: http://neo.jpl.nasa.gov/ca/

For more information on NASA's Planetary Defense Coordination Office, visit:

http://www.nasa.gov/planetarydefense

For asteroid news and updates, follow AsteroidWatch on Twitter:

http://www.twitter.com/AsteroidWatch

Images, Text, Credits: ESA/NASA/Tony Greicius/JPL/DC Agle.

Greetings, Orbiter.ch

Last main ring components leave CERN for SESAME












CERN - European Organization for Nuclear Research logo.

Feb. 3, 2016

For close to three years, CERN has coordinated the production of magnets and power supplies for the pioneering SESAME research facility under construction in Allan, Jordan. A third-generation light source, SESAME is the first facility of its kind in the region, and the first intergovernmental research organization to be established in the Middle East. Bringing together Bahrain, Cyprus, Egypt, Iran, Israel, Jordan, Pakistan, the Palestinian Authority and Turkey, SESAME will address research topics ranging from biological science to cultural heritage when its first beam lines are commissioned later this year.


Image above: The final CESSAMag components left CERN for Jordan this week. Here a SESAME dipole, supplied as part of the project, is moved to a test bench in February last year. (Image: Maximilien Brice/ CERN).

SESAME represents the culmination of a dream decades in the making. The idea of such a regional research facility was first mooted by the Pakistani Nobel Prize winning physicist, Abdus Salam, in the 1980s. In the early 1990s, a Middle East scientific co-operation group (MESC) was established to promote regional cooperation in science. In 2002, components from the BESSY1 light source in Berlin were donated to the fledgling laboratory. Upgraded, BESSY1 now has a new lease of life as the injector system for the SESAME main ring.

CERN has had a strong engagement with SESAME from the start. Theorist Sergio Fubini of CERN and Turin University was instrumental in establishing MESC. SESAME’s governance is based on the CERN model, and SESAME’s first Council President was former CERN Director General Herwig Schopper. Another former CERN Director General, Chris Llewellyn-Smith, took over from Schopper in 2008, and will in turn hand over to a third former CERN Director General, Rolf Heuer, once SESAME is running.

With today’s shipment, the CESSAMag project concludes its undertaking to deliver 17 dipoles, 66 quadrupoles and 66 sextupoles, along with power supplies and controllers to the new laboratory. CESSAMag has been a truly international collaboration, with components sourced both in Europe and in SESAME members. Half of the sextupoles were produced in Cyprus, with the remaining 33 coming as a donation to CERN from Pakistan. The sextupole coils were produced in France. Israel produced 79 power supplies, while Turkey provided 280 coils for the quadrupoles, which were built in Spain. The dipoles came from the UK, with their power supply coming from Italy. Switzerland provided controllers and further power supplies. CERN’s role was to provide the specification for all components and coordinate their production and testing at CERN and at the ALBA light source in Barcelona.  Done in collaboration with SESAME scientists, this provided a valuable knowledge transfer role.

video
Transport Magnet SESAME to Jordan

Video above: In January 2016 the main ring is transported from CERN to Jordan, marking the conclusion of the CESSAMag project (Video: Jacques Fichet/ CERN).

The final consignment, which left CERN today, will travel by sea to the Jordanian port of Aqaba, and is scheduled to arrive in Allan in six to eight weeks. Installation will run through summer, with commissioning scheduled to begin in the last quarter of 2016.

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.

Related articles:

New CERN programme to develop network between SESAME schools:
http://home.cern/about/updates/2015/10/new-cern-programme-develop-network-between-sesame-schools

SESAME: a bright hope for the Middle East:
http://home.cern/about/updates/2015/07/sesame-bright-hope-middle-east

SESAME passes an important milestone at CERN:
http://orbiterchspacenews.blogspot.ch/2015/04/sesame-passes-important-milestone-at.html

The SESAME project: http://www.sesame.org.jo/sesame/

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

Image (mentioned), Video (mentioned), Text, Credits: CERN/James Gillies/Harriet Kim Jarlett.

Greetings, Orbiter.ch

The Deep-Frozen Flying Saucer












ALMA - Atacama Large Millimeter/submillimeter Array logo.

3 February 2016

ALMA finds unexpectedly cold grains in planet-forming disc

The Flying Saucer protoplanetary disc around 2MASS J16281370-2431391

Astronomers have used the ALMA and IRAM telescopes to make the first direct measurement of the temperature of the large dust grains in the outer parts of a planet-forming disc around a young star. By applying a novel technique to observations of an object nicknamed the Flying Saucer they find that the grains are much colder than expected: −266 degrees Celsius. This surprising result suggests that models of these discs may need to be revised.

The international team, led by Stephane Guilloteau at the Laboratoire d'Astrophysique de Bordeaux, France, measured the temperature of large dust grains around the young star 2MASS J16281370-2431391 in the spectacular Rho Ophiuchi star formation region, about 400 light-years from Earth.

This star is surrounded by a disc of gas and dust — such discs are called protoplanetary discs as they are the early stages in the creation of planetary systems. This particular disc is seen nearly edge-on, and its appearance in visible light pictures has led to its being nicknamed the Flying Saucer.

The Flying Saucer protoplanetary disc around 2MASS J16281370-2431391

The astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the glow coming from carbon monoxide molecules in the 2MASS J16281370-2431391 disc. They were able to create very sharp images and found something strange — in some cases they saw a negative signal! Normally a negative signal is physically impossible, but in this case there is an explanation, which leads to a surprising conclusion.

Lead author Stephane Guilloteau takes up the story: “This disc is not observed against a black and empty night sky. Instead it’s seen in silhouette in front of the glow of the Rho Ophiuchi Nebula. This diffuse glow is too extended to be detected by ALMA, but the disc absorbs it. The resulting negative signal means that parts of the disc are colder than the background. The Earth is quite literally in the shadow of the Flying Saucer!”

The team combined the ALMA measurements of the disc with observations of the background glow made with the IRAM 30-metre telescope in Spain [1]. They derived a disc dust grain temperature of only −266 degrees Celsius (only 7 degrees above absolute zero, or 7 Kelvin) at a distance of about 15 billion kilometres from the central star [2]. This is the first direct measurement of the temperature of large grains (with sizes of about one millimetre) in such objects.

The Rho Ophiuchi star formation region in the constellation of Ophiuchus

This temperature is much lower than the −258 to −253 degrees Celsius (15 to 20 Kelvin) that most current models predict. To resolve the discrepancy, the large dust grains must have different properties than those currently assumed, to allow them to cool down to such low temperatures.

“To work out the impact of this discovery on disc structure, we have to find what plausible dust properties can result in such low temperatures. We have a few ideas — for example the temperature may depend on grain size, with the bigger grains cooler than the smaller ones. But it is too early to be sure,” adds co-author Emmanuel di Folco (Laboratoire d'Astrophysique de Bordeaux).

If these low dust temperatures are found to be a normal feature of protoplanetary discs this may have many consequences for understanding how they form and evolve.

The Rho Ophiuchi star formation region in the constellation of Ophiuchus

For example, different dust properties will affect what happens when these particles collide, and thus their role in providing the seeds for planet formation. Whether the required change in dust properties is significant or not in this respect cannot yet be assessed.

Low dust temperatures can also have a major impact for the smaller dusty discs that are known to exist. If these discs are composed of mostly larger, but cooler, grains than is currently supposed, this would mean that these compact discs can be arbitrarily massive, so could still form giant planets comparatively close to the central star.

video
Zooming in on the Flying Saucer protoplanetary disc

Further observations are needed, but it seems that the cooler dust found by ALMA may have significant consequences for the understanding of protoplanetary discs.

Notes:

[1] The IRAM measurements were needed as ALMA itself was not sensitive to the extended signal from the background.

[2] This corresponds to one hundred times the distance from the Earth to the Sun. This region is now occupied by the Kuiper Belt within the Solar System.

More information:

This research was presented in a paper entitled “The shadow of the Flying Saucer: A very low temperature for large dust grains”, by S. Guilloteau et al., published in Astronomy & Astrophysics Letters.

The team is composed of S. Guilloteau (University of Bordeaux/CNRS, Floirac, France), V. Piétu (IRAM, Saint Martin d’Hères, France), E. Chapillon (University of Bordeaux/CNRS; IRAM), E. Di Folco (University of Bordeaux/CNRS), A. Dutrey (University of Bordeaux/CNRS), T.Henning (Max Planck Institute für Astronomie, Heidelberg, Germany [MPIA]), D.Semenov (MPIA), T.Birnstiel (MPIA) and N. Grosso (Observatoire Astronomique de Strasbourg, Strasbourg, France).

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the US National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

The Institut de Radio Astronomie Millimétrique (IRAM) is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:

Photos of ALMA: http://www.eso.org/public/images/archive/search/?adv=&subject_name=Atacama%20Large%20Millimeter/submillimeter%20Array

Science paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1604/eso1604a.pdf

Related links:

Atacama Large Millimeter/submillimeter Array (ALMA): http://www.eso.org/public/teles-instr/alma/

IRAM 30-metre telescope in Spain: http://www.iram-institute.org/

Images, Text, Credits: ESO/ESA/NASA/Digitized Sky Survey 2/Acknowledgement: Davide De Martin/IAU and Sky & Telescope/Video: ESO/N. Risinger (skysurvey.org)/S. Guisard (www.eso.org/~sguisard)/Digitized Sky Survey 2/NASA/ESA. Music: Johan B. Monell (www.johanmonell.com).