SpaceX - SES-12 Mission Success

SpaceX - Falcon 9 / SES-12 Mission patch.

June 5, 2018

Image above: After the rocket’s nine Merlin engines pass an automated health check, hold-down clamps will release the Falcon 9 booster for liftoff from pad 40.

SpaceX successfully launched the SES-12 satellite to a Geostationary Transfer Orbit (GTO) on Monday, June 4, 2018 from Space Launch Complex 40 (SLC-40) at Cape Canaveral Air Force Station, Florida. Liftoff occurred at 12:45 a.m. EDT. The SES-12 satellite was deployed about 32 minutes after liftoff.

Falcon 9’s first stage for the SES-12 mission previously supported the OTV-5 mission from Launch Complex 39A in September 2017. SpaceX did not attempt to recover Falcon 9’s first stage after launch.

SES-12 Mission

SES 12 weighs 11,867 pounds (5,383 kilograms) with its supply of xenon propellant for the electric thrusters, while a satellite with similar capability would weigh up to 10 metric tons if it carried the customary hydrazine and nitrogen tetroxide propellants used by conventional spacecraft.

SES 12 satellite

The weight savings allowed SES to fit SES 12 on a smaller, less expensive rocket, and permitted engineers to combine two communications missions into one spacecraft. SES 12 will provide direct-to-home television broadcasts, video and data relay services, and broadband connectivity across the Middle East, the Asia-Pacific, and Australia during its 15-year mission.

Image above: The SES 12 satellite separates from the Falcon 9 rocket in a geostationary transfer orbit with a perigee of 182 miles (294 kilometers) and a targeted apogee of around 36,357 miles (58,511 kilometers), with an apogee range plus or minus approximately 300 miles (500 kilometers).

SES 12 will use its plasma jets to climb into a circular geostationary orbit more than 22,000 miles (nearly 36,000 kilometers) over the equator after deployment from the Falcon 9 rocket in an elliptical transfer orbit.

For more information about SES, visit: https://www.ses.com/

For more information about SpaceX, visit: http://www.spacex.com/

Images, Video, Text, Credits: SpaceX/Airbus/Spaceflight Now.com/Stephen Clark.

Greetings, Orbiter.ch

Mighty Odysseus

NASA - Cassini Mission to Saturn patch.

June 4, 2018

The most visually striking feature on Saturn’s icy moon Tethys is Odysseus crater. An enormous impact created the crater, which is about 280 miles (450 kilometers) across, with its ring of steep cliffs and the mountains that rise at its center. Odysseus is on the leading hemisphere of Tethys (1,071 kilometers, or 665 miles across). In this image, north on Tethys is up.

This view is a composite of several images taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 17, 2015, at a distance of about 28,000 miles (44,500 kilometers) from Tethys.

The Cassini spacecraft ended its mission on Sept. 15, 2017.

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit https://saturn.jpl.nasa.gov and https://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org.

Image, Text, Credits: NASA/Tony Greicius/JPL-Caltech/Space Science Institute.

Greetings, Orbiter.ch

Mars Curiosity's Labs Are Back in Action

NASA - Mars Science Laboratory (MSL) patch.

June 4, 2018

NASA's Curiosity rover is analyzing drilled samples on Mars in one of its onboard labs for the first time in more than a year.

Image above: The drill bit of NASA's Curiosity Mars rover over one of the sample inlets on the rover's deck. The inlets lead to Curiosity's onboard laboratories. This image was taken on Sol 2068 by the rover's Mast Camera (Mastcam). Image Credits: NASA/JPL-Caltech/MSSS.

"This was no small feat. It represents months and months of work by our team to pull this off," said Jim Erickson, project manager of the Mars Science Laboratory mission, which is led by NASA's Jet Propulsion Laboratory in Pasadena, California. The Curiosity rover is part of the MSL mission. "JPL's engineers had to improvise a new way for the rover to drill rocks on Mars after a mechanical problem took the drill offline in December 2016."

The rover drilled its last scheduled rock sample in October 2016.

On May 20, a technique called "feed extended drilling" allowed Curiosity to drill its first rock sample since October 2016; on May 31, an additional technique called "feed extended sample transfer" successfully trickled rock powder into the rover for processing by its mineralogy laboratory. Delivery to its chemistry laboratory will follow in the week ahead.

Testing of both the new drilling method and sample delivery will continue to be refined as Curiosity's engineers study their results from Mars. But this is a major milestone for the mission, said Ashwin Vasavada of JPL, the mission's project scientist.

"The science team was confident that the engineers would deliver -- so confident that we drove back to a site that we missed drilling before. The gambit paid off, and we now have a key sample we might have never gotten," Vasavada said. "It’s quite remarkable to have a moment like this, five years into the mission. It means we can resume studying Mount Sharp, which Curiosity is climbing, with our full range of scientific tools."

The new sample transfer technique allows Curiosity to position its drill over two small inlets on top of the rover's deck, trickling in the appropriate amount of rock powder for the onboard laboratories to do their analyses.

Image above: Artist's view of Mars Science Laboratory (MSL) rover or "Curiosity". Image Credits: NASA/JPL-Caltech.

This delivery method had already been successfully tested at JPL. But that's here on Earth; on Mars, the thin, dry atmosphere provides very different conditions for powder falling out of the drill.

"On Mars we have to try and estimate visually whether this is working, just by looking at images of how much powder falls out," said John Michael Moorokian of JPL, the engineer who led development of the new sample delivery method. "We're talking about as little as half a baby aspirin worth of sample."

Too little powder, and the laboratories can't provide accurate analyses. Too much, and it could overfill the instruments, clogging parts or contaminating future measurements. A successful test of the delivery method on May 22 led to even further improvements in the delivery technique.

Part of the challenge is that Curiosity's drill is now permanently extended. That new configuration no longer gives it access to a special device that sieves and portions drilled samples in precise amounts. That device, called the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA), played an important role in delivering measured portions of sample to the laboratories inside the rover.

For more information about Curiosity, visit: https://mars.nasa.gov/msl/

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

Greetings, Orbiter.ch

Higgs boson comes out on top

CERN - European Organization for Nuclear Research logo.

June 4, 2018

Artistic view of the Brout-Englert-Higgs Field (Image: Daniel Dominguez/CERN)

New results from the ATLAS and CMS experiments at the Large Hadron Collider (LHC) reveal how strongly the Higgs boson interacts with the heaviest known elementary particle, the top quark.

The Higgs boson interacts only with massive particles, yet it was initially discovered in its decay to two massless photons. Quantum mechanics allows the Higgs to fluctuate for a very short time into a top quark and a top anti-quark, which promptly annihilate each other into a photon pair. The probability of this process occurring varies with the strength of the interaction (known as coupling) between the Higgs boson and top quarks. Its measurement allows researchers to indirectly infer the value of the Higgs-top coupling. A more direct manifestation of the Higgs-top coupling is the emission of a Higgs boson by a top-antitop quark pair.

Graphic above: An event candidate for the production of a top quark and top antiquark pair in conjunction with a Higgs boson in CMS. The Higgs decays into a tau+ lepton, which in turn decays into hadrons and a tau-, which decays into an electron. The decay product symbols are in blue. The top quark decays into three jets (sprays of lighter particles) whose names are given in purple. One of these is initiated by a b-quark. The top antiquark decays into a muon and b-jet, whose names appear in red. (Image: CMS/CERN).

Results presented today, at the LHCP conference in Bologna, describe the observation of this so-called "ttH production" process. Results from the CMS collaboration, with a significance exceeding five standard deviations (considered the gold standard) for the first time, have just been published in the journal Physical Review Letters; including more data from the ongoing LHC-run, the ATLAS collaboration just submitted new results for publication, with a larger significance. The findings of the two experiments are consistent with one another and with the Standard Model. They tell scientists more about the properties of the Higgs boson and give clues for where to look for new physics.

Image above: Visualisation of an event from the tt̄H(γγ) analysis. The event contains two photon candidates displayed as green towers in the electromagnetic calorimeter, and six jets (b-jet) shown as yellow (blue) cones. (Image:ATLAS/CERN).

Measuring the ttH production process is challenging, as it is rare: only 1% of Higgs bosons are produced in association with two top quarks and, in addition, the Higgs and the top quarks decay into other particles in many complex ways, or modes. Using data from proton–proton collisions collected at energies of 7, 8, and 13 TeV, the ATLAS and CMS teams performed several independent searches for ttH production, each targeting different Higgs-decay modes (to W bosons, Z bosons, photons, τ leptons, and bottom-quark jets). To maximise the sensitivity to the experimentally challenging ttH signal, each experiment then combined the results from all of its searches.

"The superb performance of the LHC and the improved experimental tools in mastering this complex analysis led to this beautiful result,” added CERN Director for Research and Computing Eckhard Elsen. “It also shows that we are on the right track with our plans for the High-Luminosity LHC and the physics results it promises.”

New results proving that the top quark acquires its mass from the Higgs field

Video above: Scientists from ATLAS, CMS and the CERN theory department explain the significance of today's results. (Video: CERN).

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 links:

Large Hadron Collider (LHC): https://home.cern/topics/large-hadron-collider

ATLAS: https://home.cern/about/experiments/atlas

CMS: https://home.cern/about/experiments/cms

LHCP conference in Bologna: http://lhcp2018.bo.infn.it/

Physical Review Letters: https://doi.org/10.1103/PhysRevLett.120.231801

Standard Model: https://home.cern/about/physics/standard-model

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

Images (mentioned), Graphic (mentioned), Video (mentioned), Text, Credits: CERN/Kate Kahle.

Best regards, Orbiter.ch

ALMA and VLT Find Too Many Massive Stars in Starburst Galaxies, Near and Far

ALMA - Atacama Large Millimeter/submillimeter Array logo.

4 June 2018

Artist’s impression of a dusty starburst galaxy

Astronomers using ALMA and the VLT have discovered that both starburst galaxies in the early Universe and a star-forming region in a nearby galaxy contain a much higher proportion of massive stars than is found in more peaceful galaxies. These findings challenge current ideas about how galaxies evolved, changing our understanding of cosmic star-formation history and the build up of chemical elements.

The Tarantula Nebula in the Large Magellanic Cloud

Probing the distant Universe a team of scientists, led by University of Edinburgh astronomer Zhi-Yu Zhang, used the Atacama Large Millimeter/submillimeter Array (ALMA) to investigate the proportion of massive stars in four distant gas-rich starburst galaxies [1]. These galaxies are seen when the Universe was much younger than it is now so the infant galaxies are unlikely to have undergone many previous episodes of star formation, which might otherwise have confused the results.

Artist’s impression of a dusty starburst galaxy

Zhang and his team developed a new technique — analogous to radiocarbon dating (also known as carbon-14 dating) — to measure the abundances of different types of carbon monoxide in four very distant, dust-shrouded starburst galaxies [2]. They observed the ratio of two types of carbon monoxide containing different isotopes [3].

Artist’s impression of a starburst galaxy

“Carbon and oxygen isotopes have different origins”, explains Zhang. “18O is produced more in massive stars, and 13C is produced more in low- to intermediate-mass stars.” Thanks to the new technique the team was able to peer through the dust in these galaxies and assess for the first time the masses of their stars.

ALMA observations of four distant starburst galaxies

The mass of a star is the most important factor determining how it will evolve. Massive stars shine brilliantly and have short lives and less massive ones, such as the Sun, shine more modestly for billions of years. Knowing the proportions of stars of different masses that are formed in galaxies therefore underpins astronomers’ understanding of the formation and evolution of galaxies throughout the history of the Universe. Consequently, it gives us crucial insights about the  chemical elements available to form new stars and planets and, ultimately, the number of seed black holes that may coalesce to form the supermassive black holes that we see in the centres of many galaxies.

Artist’s impression of distant starburst galaxy

Co-author Donatella Romano from the INAF-Astrophysics and Space Science Observatory in Bologna explains what the team found: “The ratio of 18O to 13C was about 10 times higher in these starburst galaxies in the early Universe than it is in galaxies such as the Milky Way, meaning that there is a much higher proportion of massive stars within these starburst galaxies.”

The ALMA finding is consistent with another discovery in the local Universe. A team led by Fabian Schneider of the University of Oxford, UK, made spectroscopic measurements with ESO’s Very Large Telescope of 800 stars in the gigantic star-forming region 30 Doradus in the Large Magellanic Cloud in order to investigate the overall distribution of stellar ages and initial masses [4].

Schneider explained, “We found around 30% more stars with masses more than 30 times that of the Sun than expected, and about 70% more than expected above 60 solar masses. Our results challenge the previously predicted 150 solar mass limit for the maximum birth mass of stars and even suggest that stars could have birth masses up to 300 solar masses!”

Rob Ivison, co-author of the new ALMA paper, concludes: “Our findings lead us to question our understanding of cosmic history. Astronomers building models of the Universe must now go back to the drawing board, with yet more sophistication required.”

Notes:

[1] Starburst galaxies are galaxies that are undergoing an episode of very intense star formation. The rate at which they form new stars can be 100 times or more the rate in our own galaxy, the Milky Way. Massive stars in these galaxies produce ionising radiation, stellar outflows, and supernova explosions, which significantly influence the dynamical and chemical evolution of the medium around them. Studying the mass distribution of stars in these galaxies can tell us more about their own evolution, and also the evolution of the Universe more generally.

[2] The radiocarbon dating method is used for determining the age of an object containing organic material. By measuring the amount of 14C, which is a radioactive isotope whose abundance continuously decreases, one can calculate when the animal or plant died. The isotopes used in the ALMA study, 13C and 18O, are stable and their abundances continuously increase during the lifetime of a galaxy, being synthesised by thermal nuclear fusion reactions inside stars.

[3] These different forms of the molecule are called isotopologues and they differ in the number of neutrons they can have. The carbon monoxide molecules used in this study are an example of such molecular species, because a stable carbon isotope can have either 12 or 13 nucleons in its nucleus, and a stable oxygen isotope can have either 16, 17, or 18 nucleons.

[4] Schneider et al. made spectroscopic observations of individual stars in 30 Doradus, a star-forming region in the nearby Large Magellanic Cloud, using the Fibre Large Array Multi Element Spectrograph (FLAMES) on the Very Large Telescope (VLT). This study was one of the first to be carried out that has been detailed enough to show that the Universe is able to produce star-forming regions with different mass distributions from that in the Milky Way.

More information:

The ALMA results are published in a paper entitled “Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time” that will appear in Nature on 4 June 2018. The VLT results are published in a paper entitled “An excess of massive stars in the local 30 Doradus starburst”, which has been published in Science on 5 January 2018.

The ALMA team is composed of: Z. Zhang (Institute for Astronomy, University of Edinburgh, Edinburgh, UK; European Southern Observatory, Garching bei München, Germany), D. Romano (INAF, Astrophysics and Space Science Observatory, Bologna, Italy), R. J. Ivison (European Southern Observatory, Garching bei München, Germany; Institute for Astronomy, University of Edinburgh, Edinburgh, UK), P .P. Papadopoulos  (Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece; Research Center for Astronomy, Academy of Athens, Athens, Greece;) and F. Matteucci (Trieste University; INAF, Osservatorio Astronomico di Trieste; INFN, Sezione di Trieste, Trieste, Italy)

The VLT team is composed of: F. R. N. Schneider ( Department of Physics, University of Oxford, UK), H. Sana (Institute of Astrophysics, KU Leuven, Belgium), C. J. Evans ( UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. M. Bestenlehner (Max-Planck-Institut für Astronomie, Heidelberg, Germany; Department of Physics and Astronomy, University of Sheffield, UK), N. Castro (Department of Astronomy, University of Michigan, USA), L. Fossati (Austrian Academy of Sciences, Space Research Institute, Graz, Austria), G. Gräfener (Argelander-Institut für Astronomie der Universität Bonn, Germany), N. Langer (Argelander-Institut für Astronomie der Universität Bonn, Germany), O. H. Ramírez-Agudelo (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), C. Sabín-Sanjulián (Departamento de Física y Astronomía, Universidad de La Serena, Chile), S. Simón-Díaz (Instituto de Astrofísica de Canarias, Tenerife, Spain; Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain),  F. Tramper (European Space Astronomy Centre, Madrid, Spain), P. A. Crowther (Department of Physics and Astronomy, University of Sheffield, UK), A. de Koter (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands; Institute of Astrophysics, KU Leuven, Belgium), S. E. de Mink (Astronomical Institute Anton Pannekoek, Amsterdam University, Netherlands), P. L. Dufton (Astrophysics Research Centre, School of Mathematics and Physics, Queen’s University Belfast, Northern Ireland, UK), M. Garcia (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), M. Gieles (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK), V. Hénault-Brunet (National Research Council, Herzberg Astronomy and Astrophysics, Canada; Department of Astrophysics/Institute for Mathematics, Astrophysics and Particle Physics, Radboud University, Netherlands), A. Herrero (Departamento de Física y Astronomía, Universidad de La Serena, Chile), R. G. Izzard (Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, UK; Institute of Astronomy, The Observatories, Cambridge, UK), V. Kalari (Departamento de Astronomía, Universidad de Chile, Santiago, Chile), D. J. Lennon (European Space Astronomy Centre, Madrid, Spain), J. Maíz Apellániz (Centro de Astrobiología, CSIC–INTA, European Space Astronomy Centre campus, Villanueva de la Cañada, Spain), N. Markova (Institute of Astronomy with National Astronomical Observatory, Bulgarian Academy of Sciences, Smolyan, Bulgaria), F. Najarro (Centro de Astrobiología, CSIC-INTA, Madrid, Spain), Ph. Podsiadlowski (Department of Physics, University of Oxford, UK; Argelander-Institut für Astronomie der Universität Bonn, Germany), J. Puls (Ludwig-Maximilians-Universität München, Germany), W. D. Taylor (UK Astronomy Technology Centre, Royal Observatory Edinburgh, Edinburgh, UK), J. Th. van Loon (Lennard-Jones Laboratories, Keele University, Staffordshire, UK), J. S. Vink (Armagh Observatory, Northern Ireland, UK) and C. Norman (Johns Hopkins University, Baltimore, USA; Space Telescope Science Institute, Baltimore, USA)

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It has 15 Member States: Austria, Belgium, 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 and with Australia as a strategic partner. 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 and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

Links:

Zhang et al. research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1817/eso1817a.pdf

Schneider et al. research paper: http://www.eso.org/public/archives/releases/sciencepapers/eso1817/eso1817b.pdf

ESOcast 163 Light: Too Many Massive Stars in Starburst Galaxies: https://www.eso.org/public/videos/eso1817a/

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

Photos of the VLT: http://www.eso.org/public/images/archive/search/?adv=&subject_name=Very%20Large%20Telescope

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

ESO’s Very Large Telescope (VLT): http://eso.org/vlt

Images, Video, Text, Credits: ESO/Mariya Lyubenova/Rob Ivison/M. Kornmesser/Department of Physics — University of Oxford/Fabian Schneider/University of Edinburgh and ESO/Zhi-Yu Zhang/ALMA (ESO/NAOJ/NRAO), Zhang et al.

Best regards, Orbiter.ch

Tiny Asteroid Discovered Saturday Disintegrates Hours Later Over Southern Africa

Asteroid Watch logo.

June 4, 2018

Artist's concept of a near-Earth object. Image Credits: NASA/JPL-Caltech

A boulder-sized asteroid designated 2018 LA was discovered Saturday morning, June 2, and was determined to be on a collision course with Earth, with impact just hours away. Because it was very faint, the asteroid was estimated to be only about 6 feet (2 meters) across, which is small enough that it was expected to safely disintegrate in Earth's atmosphere. Saturday's asteroid was first discovered by the NASA-funded Catalina Sky Survey, located near Tucson and operated by the University of Arizona.

How Does NASA Spot a Near-Earth Asteroid

Video above: Did you ever wonder how NASA spots asteroids that maybe getting too close to Earth for comfort? Watch and learn. Find out more about NASA finds, studies and tracks near-Earth objects by visiting: https://www.nasa.gov/planetarydefense.

Although there was not enough tracking data to make precise predictions ahead of time, a swath of possible locations was calculated stretching from Southern Africa, across the Indian Ocean, and onto New Guinea. Reports of a bright fireball above Botswana, Africa, early Saturday evening match up with the predicted trajectory for the asteroid. The asteroid entered Earth's atmosphere at the high speed of 10 miles per second (38,000 mph, or 17 kilometers per second) at about 16:44 UTC (9:44 a.m. PDT, 12:44 p.m. EDT,6:44 p.m. local Botswana time) and disintegrated several miles above the surface, creating a bright fireball that lit up the evening sky. The event was witnessed by a number of observers and was caught on webcam video.

Meteor ZLAF9B2 seen from between Ottosdal and Hartebeesfontein North West South Africa

Video above: Meteor ZLAF9B2 seen from between Ottosdal and Hartebeesfontein North West South Africa. Video Credit: Barend Swanepoel/YouTube.

When it was first detected, the asteroid was nearly as far away as the Moon's orbit, although that was not initially known. The asteroid appeared as a streak in the series of time-exposure images taken by the Catalina telescope . As is the case for all asteroid-hunting projects, the data were quickly sent to the Minor Planet Center in Cambridge, Massachusetts, which calculated a preliminary trajectory indicating the possibility of an Earth impact. The data were in turn sent to the Center for Near-Earth Object Studies (CNEOS) at NASA's Jet Propulsion Laboratory in Pasadena, California, where the automated Scout system also found a high probability that the asteroid was on an impact trajectory. Automated alerts were sent out to the community of asteroid observers to obtain further observations, and to the Planetary Defense Coordination Office at NASA Headquarters in Washington. However, since the asteroid was determined to be so small and therefore harmless, no further impact alerts were issued by NASA.

"This was a much smaller object than we are tasked to detect and warn about," said Lindley Johnson, Planetary Defense Officer at NASA Headquarters. "However, this real-world event allows us to exercise our capabilities and gives some confidence our impact prediction models are adequate to respond to the potential impact of a larger object."

Asteroid 2018 LA

Image above: These are the discovery observations of asteroid 2018 LA from the Catalina Sky Survey, taken June 2, 2018. About eight hours after these images were taken, the asteroid entered Earth's atmosphere (about 9:44 a.m. PDT, 12:44 p.m. EDT, 16:44 UTC, 6:44 p.m. local Botswana time), and disintegrated in the upper atmosphere near Botswana, Africa. Image Credits: NASA/JPL-Caltech/CSS-Univ. of Arizona.

The ATLAS asteroid survey obtained two additional observations hours before impact, which were used by Scout to confirm the impact would occur, and narrowed down the predicted location to southern Africa. Infrasound data collected just after the impact clearly detected the event from one of the listening stations deployed as part of the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty. The signal is consistent with an atmospheric impact over Botswana.

"The discovery of asteroid 2018 LA is only the third time that an asteroid has been discovered to be on an impact trajectory, said Paul Chodas, manager of the Center for Near-Earth Object Studies (CNEOS) at JPL. "It is also only the second time that the high probability of an impact was predicted well ahead of the event itself."

The first event of this kind was the impact of asteroid 2008 TC3, which lit up the predawn sky above Northern Sudan on October 7, 2008. That was a slightly larger asteroid (about 13 feet, or 4 meters in size), and it was discovered a full 19 hours before impact, allowing for a large number of follow-up observations and a very precise trajectory to be calculated. The second predicted impact event was for asteroid 2014 AA, which was discovered only a few hours before impact on Jan. 1, 2014, in the Atlantic Ocean, leaving too little time for follow-up observations. The Catalina Sky Survey has been responsible for discovering all three of these small asteroids on impact trajectories, and all on the watch of the same observer, Richard Kowalski.

NASA's Planetary Defense Coordination Office is responsible for finding, tracking and characterizing potentially hazardous asteroids and comets coming near Earth, issuing warnings about possible impacts, and assisting coordination of U.S. government response planning, should there be an actual impact threat. JPL hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program, an element of the Planetary Defense Coordination Office within the agency's Science Mission Directorate.

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

https://www.nasa.gov/planetarydefense

More information about asteroids and near-Earth objects can be found at:

https://cneos.jpl.nasa.gov

https://www.jpl.nasa.gov/asteroidwatch

For asteroid and comet news and updates, follow AsteroidWatch on Twitter:

https://twitter.com/AsteroidWatch

Images (mentioned), Video (mentioned), Text, Credits: NASA/Dwayne Brown/JPL/DC Agle.

Greetings, Orbiter.ch

Crewmates Safely Return to Earth from Space Station

ROSCOSMOS - Soyuz MS-07 Mission patch.

June 3, 2018

Three members of the International Space Station Expedition 55 crew, including NASA astronaut Scott Tingle, returned to Earth Sunday after 168 days of living and working in low-Earth orbit.

Tingle, astronaut Norishige Kanai of the Japan Aerospace Exploration Agency, and cosmonaut Anton Shkaplerov of the Russian space agency Roscosmos landed at 8:39 a.m. EDT (6:39 p.m. in Kazakhstan) southeast of the remote town of Dzhezkazgan in Kazakhstan.

Images above: After 168 days of living and working in low-Earth orbit, three members of the International Space Station Expedition 55 crew - NASA astronaut Scott Tingle, cosmonaut Anton Shkaplerov of the Russian space agency Roscosmos and astronaut Norishige Kanai of the Japan Aerospace Exploration Agency - return to Earth Sunday, June 3, 2018, landing at 8:39 a.m. EDT (6:39 p.m. in Kazakhstan) southeast of the remote town of Dzhezkazgan in Kazakhstan. Images Credits: NASA Television.

This mission was the first for Tingle and Kanai, and Shkaplerov now has logged 532 days in space on three flights. The crew completed hundreds of experiments, including materials testing, a study of the effect of microgravity on the bone marrow and research into plant growth in space.

They also welcomed four cargo spacecraft delivering several tons of supplies and experiments. A SpaceX Dragon spacecraft arrived at the station in December, followed by another Dragon in April and Orbital ATK’s Cygnus resupply spacecraft in May. A Russian Progress cargo craft arrived at the station in February.

Tingle and Kanai ventured outside the station on separate spacewalks to perform work on parts of the Canadarm2 robotic arm. They also participated in dozens of educational events as part of NASA’s Year of Education on Station.

Landing of Soyuz MS-07 as 3 Crew Mates Return to Earth

Shkaplerov conducted a record-setting spacewalk in February with fellow cosmonaut Alexander Misurkin to replace an electronics box for a communications antenna on the Zvezda service module. The spacewalk timed out at 8 hours and 13 minutes – the longest in Russian space program history.

The Expedition 56 crew – Commander Drew Feustel and Ricky Arnold of NASA, and Oleg Artemyev of Roscosmos – will operate the station and prepare for the arrival of three new crew members on Friday, June 8. Serena Auñón-Chancellor of NASA, Alexander Gerst of ESA (European Space Agency), and Sergey Prokopyev of Roscosmos are scheduled to launch Wednesday, June 6, from Baikonur, Kazakhstan. NASA Television will broadcast the launch and docking to the space station.

Related links:

Materials testing: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=7515

The effect of microgravity on the bone marrow: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1673

Plant growth in space: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7581

Canadarm2: https://www.nasa.gov/mission_pages/station/structure/elements/mss.html

Year of Education on Station: https://www.nasa.gov/audience/foreducators/stem-on-station/year-of-education.html

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

Expedition 55: https://www.nasa.gov/mission_pages/station/expeditions/expedition55/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), Video (NASA TV), Text, Credits: NASA/Kathryn Hambleton/Karen Northon/JSC/Gary Jordan.

Greetings, Orbiter.ch