Stellar Lab in Sagittarius

ESO - European Southern Observatory logo.

10 August 2016

The star cluster Messier 18 and its surroundings

The small smattering of bright blue stars in the upper left of this vast new 615 megapixel ESO image is the perfect cosmic laboratory in which to study the life and death of stars. Known as Messier 18 this star cluster contains stars that formed together from the same massive cloud of gas and dust. This image, which also features red clouds of glowing hydrogen and dark filaments of dust, was captured by the VLT Survey Telescope (VST) located at ESO’s Paranal Observatory in Chile.

Messier 18 was discovered and catalogued in 1764 by Charles Messier — for whom the Messier Objects are named — during his search for comet-like objects [1]. It lies within the Milky Way, approximately 4600 light-years away in the constellation of Sagittarius, and consists of many sibling stars loosely bound together in what is known as an open cluster.

The star cluster Messier 18 in the constellation of Sagittarius

There are over 1000 known open star clusters within the Milky Way, with a wide range of properties, such as size and age, that provide astronomers with clues to how stars form, evolve and die. The main appeal of these clusters is that all of their stars are born together out of the same material.

In Messier 18 the blue and white colours of the stellar population indicate that the cluster’s stars are very young, probably only around 30 million years old. Being siblings means that any differences between the stars will only be due to their masses, and not their distance from Earth or the composition of the material they formed from. This makes clusters very useful in refining theories of star formation and evolution.

Wide-field view of the region around the star cluster Messier 18

Astronomers now know that most stars do form in groups, forged from the same cloud of gas that collapsed in on itself due to the attractive force of gravity. The cloud of leftover gas and dust — or molecular cloud — that envelops the new stars is often blown away by their strong stellar winds, weakening the gravitational shackles that bind them. Over time, loosely bound stellar siblings like those pictured here will often go their separate ways as interactions with other neighbouring stars or massive gas clouds nudge, or pull, the stars apart. Our own star, the Sun, was most likely once part of a cluster very much like Messier 18 until its companions were gradually distributed across the Milky Way.

Zooming in on the star cluster Messier 18

The dark lanes that snake through this image are murky filaments of cosmic dust, blocking out the light from distant stars. The contrasting faint reddish clouds that seem to weave between the stars are composed of ionised hydrogen gas. The gas glows because young, extremely hot stars like these are emitting intense ultraviolet light which strips the surrounding gas of its electrons and causes it to emit the faint glow seen in this image. Given the right conditions, this material could one day collapse in on itself and provide the Milky Way with yet another brood of stars — a star formation process that may continue indefinitely (eso1535).

Close-up look at the region around the star cluster Messier 18

This mammoth 30 577 x 20 108 pixel image was captured using the OmegaCAM camera, which is attached to the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile.

Notes:

[1] Messier 18 is also listed in the New General Catalogue as NGC 6613.

More information:

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:

VLT Survey Telescope (VST): http://www.eso.org/public/teles-instr/surveytelescopes/vst/

ESO Information on OmegaCAM: https://www.eso.org/public/teles-instr/surveytelescopes/vst/camera/

eso1535: http://www.eso.org/public/news/eso1535/

Images, Text, Credits: ESO/IAU and Sky & Telescope/Digitized Sky Survey 2. Acknowledgement: Davide De Martin/Videos: ESO/Digitized Sky Survey 2/N. Risinger (skysurvey.org). Music: Johan B. Monell (www.johanmonell.com).

Best regards, Orbiter.ch

NASA's IMERG Measures Hurricane Earl's Deadly Rainfall in Mexico

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

Aug. 9, 2016

Hurricane Earl began as a tropical wave that was tracked by the National Hurricane Center (NHC) from the African coast to the Caribbean Sea. The tropical wave drenched the Dominican Republic, where it was blamed for the deaths of six people. Southwest of Jamaica on Aug. 2, 2016, the tropical wave developed a closed circulation, and Earl was upgraded to a tropical storm.

Image above: The analysis of rainfall from Aug. 2 through Aug. 8, 2016, showed the period from when Earl became a tropical storm until Earl's remnants interacted with an area of disturbed weather along the Pacific coast. Some areas in extreme southern Mexico received up to 43.3 inches (1,100 mm) of rain. Earl's locations and intensities, as defined by the National Hurricane Center (NHC), are shown overlaid in white. Image Credits: NASA/JAXA/Hal Pierce.

On Aug. 3, Earl became a hurricane when it was located about 150 miles east of Belize. On Aug. 4 Earl made landfall just southwest of Belize City, Belize, at about 2 a.m. EDT (6 a.m. UTC). At landfall Earl had winds of about 81 mph (70 knots). Earl weakened to tropical depression intensity over the Yucatan but regained tropical storm wind speeds of about 58 mph (50 knots) when it emerged over the Bay of Campeche. On Aug. 6, Earl hit Mexico again just south of Veracruz. Earl was then disrupted by Mexico's rough terrain and dissipated.

Data from NASA's Integrated Multi-satellite Retrievals for GPM (IMERG) were used to estimate the amount of rain that fell from Aug. 2 through Aug. 8. GPM is the Global Precipitation Measurement mission, a joint mission of NASA and the Japan Aerospace Exploration Agency.

Animation Credits: NASA/JAXA/Hal Pierce

The analysis, created at NASA's Goddard Space Flight Center in Greenbelt, Maryland, showed rainfall over the period from when Earl became a tropical storm until Earl's remnants interacted with an area of disturbed weather along the Pacific coast. Some areas in extreme southern Mexico received up to 43.3 inches (1,100 mm) of rain.

The IMERG analysis showed the extreme amount of rain that was dropped by Earl over Belize, Guatemala, eastern Mexico and Mexico's Pacific coast.

According to the official Twitter account of Luis Puente, Mexico’s national civil protection coordinator, at least 40 people were reported killed by landslides in the Mexican states of Puebla and Veracruz.

The remnants of Earl interacted with an area of disturbed weather along the Pacific coast of Mexico and aided in the formation of a tropical depression that became Tropical Storm Javier on Aug. 7.

Related article:

GPM Looks at Historic Flooding from Slow-Moving Maryland Storms
http://orbiterchspacenews.blogspot.ch/2016/08/gpm-looks-at-historic-flooding-from.html

Related Links:

NASA's Earl coverage: http://www.nasa.gov/feature/goddard/2016/earl-caribbean-sea

GPM (Global Precipitation Measurement): http://www.nasa.gov/mission_pages/GPM/main/index.html and http://global.jaxa.jp/projects/sat/gpm/topics.html

Image (mentioned), Animation (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Hal Pierce/Rob Gutro/Rob Garner.

Greetings, Orbiter.ch

Infrared Saturn Clouds

NASA - Cassini Mission to Saturn patch.

Aug. 9, 2016

This false-color view from NASA's Cassini spacecraft shows clouds in Saturn's northern hemisphere. The view was produced by space imaging enthusiast Kevin M. Gill, who also happens to be an engineer at NASA's Jet Propulsion Laboratory.

The view was made using images taken by Cassini's wide-angle camera on July 20, 2016, using a combination of spectral filters sensitive to infrared light at 750, 727 and 619 nanometers.

Filters like these, which are sensitive to absorption and scattering of sunlight by methane in Saturn's atmosphere, have been useful throughout Cassini's mission for determining the structure and depth of cloud features in the atmosphere.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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 http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Image, Text, Credits: NASA/JPL-Caltech/Space Science Institute/Kevin M. Gill/Sarah Loff.

Best regards, Orbiter.ch

Salvaged Galileos to help satnav specialists find their way

ESA - Galileo logo.

9 August 2016

Europe’s fifth and sixth Galileo satellites, which were salvaged from their faulty launch into working orbits, are set to begin broadcasting working navigation signals for test purposes.

This activation will allow satnav receiver manufacturers, service providers and scientific researchers to make use of these test signals. A decision on whether these satellites will become part of the operational Galileo constellation is due to be taken by the European Commission.

Galileos in orbit

A malfunction in their Soyuz-Fregat upper stage during their 22 August 2014 launch placed Galileos 5 and 6 into highly elliptical – or elongated orbits – instead of their planned circular medium-Earth orbits.

A team based at ESA’s ESOC control centre in Darmstadt, Germany, then performed a complex series of manoeuvres to raise and circularise their orbits.

The satellites lacked sufficient fuel to reach their originally envisaged orbits, but the salvage meant that their navigation payloads could then be operated on an ongoing basis; their initial orbits dipped the satellites too close to Earth to keep their antennas properly locked on the planet.

Controlling Galileo

“Once their orbits were modified, their navigation payloads could be turned on and in-orbit testing could take place,” explains Marco Falcone, Head of the Galileo System Office “The good news was their performance was excellent.

“Now they will be tested on a more sustained basis, along with the rest of the Galileo satellites. A pair of ‘Notice Advisory to Galileo Users’ (NAGUs) informing the user community of their availability for testing purposes have been published on the European Global Navigation Satellite System Service Centre website. Users are welcome to provide feedback on their usage of GSAT0201 and GSAT0202 by contacting the GSC helpdesk.

“On our side, switching on their navigation signals allows us to evaluate the entire spectrum of performance of the satellites on an end-to-end basis.

Corrected orbits 

“The navigation signals will include a signal health status reading that ‘signal component currently in test’ and its navigation data validity status will be ‘working without guarantee’. In this way, these signals will not disturb the performance of any receivers using the Galileo signals coming from the other satellites.

“On the user community side, some application providers are interested in harnessing as many available satellites as possible for precision applications.”

Because these satellites are not placed in nominal Galileo orbits, the orbital almanacs included in Galileo’s navigation signal will leave out their orbital positions, making Galileos 5 and 6 harder for receivers to locate – although the GSA website will give acquisition details.

Satnav signals

Their testing will take place in two phases: initially their navigation signal will be updated via the Galileo ground segment every 14 hours or so. Later on this year, the ground segment will be reconfigured to upgrade the update frequency more often, greatly enhancing their navigation precision – although they will remain outside the official Galileo constellation until decided otherwise.

The two satellites have not been idle since their in-orbit testing was completed. Instead, they are midway through an ambitious space experiment to test Einstein’s General Theory of Relativity more precisely than ever before, by measuring how their onboard time varies in accordance with their altitude and therefore gravity, known as their ‘gravitational redshift’.

This experiment uses only the carrier wave of the signals, so will be unaffected by the transmission of navigation messages by satellites 5 and 6.

About Galileo:

Galileo FOC

The Galileo programme is funded and owned by the EU. The European Commission has the overall responsibility for the programme, managing and overseeing the implementation of all programme activities.

Galileo’s deployment, the design and development of the new generation of systems and the technical development of infrastructure are entrusted to ESA. The definition, development and in-orbit validation phases were carried out by ESA, and co-funded by ESA and the European Commission.

The Commission and ESA have signed a delegation agreement by which ESA acts as design and procurement agent on behalf of the Commission.

The European Global Navigation Satellite System Agency (GSA) is ensuring the uptake and security of Galileo. Galileo operations and provision of services will be entrusted to the GSA from 2017.

Related articles:

Galileos 5 & 6: Salvage in space:

Salvaged Galileo performs its first navigation fix
http://orbiterchspacenews.blogspot.ch/2014/12/salvaged-galileo-performs-its-first.html

Sixth Galileo satellite reaches corrected orbit
http://orbiterchspacenews.blogspot.ch/2015/03/sixth-galileo-satellite-reaches.html

Galileo satellite recovered and transmitting navigation signals
http://orbiterchspacenews.blogspot.ch/2014/12/galileo-satellite-recovered-and.html

Galileo satellite set for new orbit
http://orbiterchspacenews.blogspot.ch/2014/11/galileo-satellite-set-for-new-orbit.html

Soyuz lifts off from French Guiana with the first fully-operational Galileo spacecrafts
http://orbiterchspacenews.blogspot.ch/2014/08/soyuz-lifts-off-from-french-guiana-with.html

Related links:

Galileo Tour: http://esamultimedia.esa.int/multimedia/Galileo_tour/galileo.swf?lang=gb&mylang=gb

EC Galileo website: http://ec.europa.eu/growth/sectors/space/galileo/index_en.htm

European GNSS Agency: http://www.gsa.europa.eu/

NAGU for Galileo 5 and NAGU for Galileo 6: http://www.gsc-europa.eu/notice-advisory-to-galileo-users-nagu-2016030

GSC helpdesk: http://www.gsc-europa.eu/

Images, Text, Credits: ESA/P. Carril.

Greetings, Orbiter.ch

NuSTAR Principal Investigator Honored for Research

NASA - NuStar Mission logo.

August 9, 2016

Fiona Harrison, principal investigator of NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) mission, has been selected to receive the 2016 Massey Award, given by the Committee on Space Research (COSPAR).

The Massey Award honors "outstanding contributions to the development of space research in which a leadership role is of particular importance" and honors the memory of Sir Harrie Massey.

Image above: Fiona Harrison is the principal investigator of NASA's NuSTAR mission, based at Caltech. Image Credit: Caltech.

"It has been great to work with such a strong and talented team on NuSTAR," said Harrison, a professor of astronomy at Caltech. "The whole team deserves credit in NuSTAR's success."

NuSTAR launched in June 2012, opening a new window to the universe as the first focusing telescope to operate in a high-frequency band of X-rays called hard X-rays.

Among NuSTAR's accomplishments so far, the observatory created the first map of radioactive material in a supernova remnant. The remnant, called Cassiopeia A, is the blown out pieces of an exploded star, which produced traces of the radioactive isotope titanium-44. NuSTAR also detected this substance in the remnant of supernova 1987A in the Large Magellanic Cloud. Such research shows how shock waves likely rip apart large dying stars.

Image above: This artist's concept shows NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) spacecraft on orbit. Image Credits: NASA/JPL-Caltech.

The NuSTAR team also discovered emission from a special type of neutron star called a magnetar, which has an extremely strong magnetic field. This object was the first pulsar -- a dead stellar remnant that emits beams of radiation as it spins -- discovered near the black hole at the center of the Milky Way.

Additionally, astronomers used NuSTAR data to find the brightest pulsar ever recorded. This astonishing object has helped astronomers refine their theories about sources of blinding X-rays called ultraluminous X-ray sources (ULXs). Most scientists believed that these sources were black holes more than 1,000 times the mass of our sun. But NuSTAR found that one such source, the extremely bright Messier 82, is actually a pulsar, not a black hole.

Image above: NuSTAR helped make the first map of radioactivity in a supernova remnant -- the blown-out bits and pieces of a massive star that exploded. Image credits: NASA/JPL-Caltech/CXC/SAO.

"These and many other discoveries make Fiona Harrison one of the most active leaders of modern high energy astrophysics," the award citation notes.

Harrison has been the principal investigator since the mission was founded in 2005. After earning a doctoral degree in physics at the University of California, Berkeley, she first came to Caltech in 1993 as a research fellow. She began her professorial career at Caltech in 1995, and is currently the Benjamin M. Rosen Professor of Physics and Kent and Joyce Kresa Leadership Chair of the Division of Physics, Mathematics and Astronomy there.

The mission will continue to allow astronomers to explore such topics as the evolution of massive black holes, the deaths of stars and the creation of heavy elements in supernova explosions.

Related link:

The first map of radioactive material in a supernova remnant: http://www.jpl.nasa.gov/news/news.php?feature=4052

Related article:

The brightest pulsar ever recorded:

NASA’s NuSTAR Telescope Discovers Shockingly Bright Dead Star
http://orbiterchspacenews.blogspot.ch/2014/10/nasas-nustar-telescope-discovers.html

For more information on NuSTAR, visit:

http://www.nasa.gov/nustar

http://nustar.caltech.edu

Images (mentioned), Text, Credits: NASA/JPL/Elizabeth Landau.

Greetings, Orbiter.ch

Rosetta celebrates two incredible years at the comet

ESA - Rosetta Mission patch.

August 8, 2016

Two incredible years have passed since ESA’s comet-chaser Rosetta arrived at Comet 67P/Churyumov-Gerasimenko on 6 August 2014.

During that time Rosetta has mapped the comet’s curious shape and given us awe-inspiring views from near and far, spotting changes in its surface features and watching as jets of gas and dust stream out in to space – sometimes unexpectedly as sudden outbursts.

Image above: Comet on 6 August 2016 – NavCam. Image Credits: ESA/Rosetta/NavCam – CC BY-SA IGO 3.0.

The spacecraft has performed daring close flybys and made distant excursions to sample gas, dust and plasma at a range of distances, giving unparalleled insight into the processes that operate at the comet and how it interacts with its environment as it hurtles through space.

In two years, the comet has travelled around 1.5 billion km along its orbit around the Sun, passing through perihelion last August – its closest approach to the Sun – and putting on a spectacular fireworks display as its activity reached a maximum.

Unlike this time last year, when the comet was so active that Rosetta could only observe it from a safe distance of 200–300 km, the activity has since subsided and the spacecraft is now operating at much closer distances, as reflected in this image, captured on 6 August 2016 from 8.5 km. The scale is 0.7 m/pixel and the image measures about 700 m across.

It shows a close-up view of part of the comet’s small lobe, encapsulating some of the large depression known as Hatmehit and its steep cliff walls (left), and the contrasting heavily fractured terrain of Wosret (bottom) and Bastet (top). A portion of the horizon is also captured in the distance, at the top right.

Image above: Full-frame NAVCAM image taken on 5 August 2014 from a distance of about 145 km from comet 67P/Churyumov-Gerasimenko. Image Credits: ESA/Rosetta/NAVCAM.

Local variations in topography and individual large boulders cast impressive shadows across the scene. For example, the details of the cliff edge at the top left are recorded in the shadows it casts on the floor below.

The area close to the bottom of the image has been the focus of imaging campaigns attempting to find Rosetta’s lander Philae, where it is thought to have bounced in November 2014, but has yet to be confirmed.

With Rosetta still flying alongside, the comet is now heading back towards the outer Solar System. As such, power is falling, and Rosetta’s thrilling mission will soon conclude in a grand finale: it will make a controlled impact onto the surface of the comet on 30 September.

Related article:

Rosetta finale set for 30 September
http://orbiterchspacenews.blogspot.ch/2016/06/rosetta-finale-set-for-30-september.html

Related links:

Comet viewer tool: http://sci.esa.int/comet-viewer/

Where is Rosetta?: http://sci.esa.int/where_is_rosetta/

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

Image (mentioned), Text, Credit: European Space Agency (ESA).

Best regards, Orbiter.ch

Long Divisions

NASA - Cassini International logo.

Aug. 8, 2016

The shadow of Saturn on the rings, which stretched across all of the rings earlier in Cassini's mission (see PIA08362), now barely makes it past the Cassini division.

The changing length of the shadow marks the passing of the seasons on Saturn. As the planet nears its northern-hemisphere solstice in May 2017, the shadow will get even shorter. At solstice, the shadow's edge will be about 28,000 miles (45,000 kilometers) from the planet's surface, barely making it past the middle of the B ring.

The moon Mimas is a few pixels wide, near the lower left in this image.

This view looks toward the sunlit side of the rings from about 35 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on May 21, 2016.

The view was obtained at a distance of approximately 2.0 million miles (3.2 million kilometers) from Saturn. Image scale is 120 miles (190 kilometers) per pixel.

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 http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini. The Cassini imaging team homepage is at http://ciclops.org and ESA's website: http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Related link:

PIA08362: http://photojournal.jpl.nasa.gov/catalog/PIA08362

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

Greetings, Orbiter.ch