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Sonntag, 26. Februar 2017 - 19:00 Uhr

Raumfahrt - Startvorbereitung für Falcon-9 mit Iridium-Satelliten

26.02.2017

Iridium Launch of Next Satellites Delayed 8 Weeks at Vandenberg Air Force Base

Backlog of SpaceX's Falcon 9 rocket launches blamed for postponing mission from planned April date

A Falcon 9 rocket blasts off from Space Launch Complex-4 at Vandenberg Air Force Base on Jan. 14. The rocket was carrying the first 10 Iridium Next satellites.Click to view larger
A Falcon 9 rocket blasts off from Space Launch Complex-4 at Vandenberg Air Force Base on Jan. 14. The rocket was carrying the first 10 Iridium Next satellites. (SpaceX photo)
 

Due to a backlog of Falcon 9 rocket missions, the second set of Iridium Next satellites won’t fly until mid-June from Vandenberg Air Force Base.

Iridium Communications Inc. announced an eight-week delay for the next 10 second-generation spacecraft.

Once planned for mid-April, the date slipped due to a backlog for the Space Exploration Technologies rocket following a Sept. 1 anomaly during an on-pad test in Florida.

 

After the June missions, SpaceX is targeting six subsequent Iridium Next launches at approximately two-month intervals, Iridium officials said.

The first 10 Iridium Next satellites headed into orbit aboard a Falcon 9 rocket launched Jan. 14 from south Vandenberg’s Space Launch Complex-4.

“After such a successful first launch, we are eager to maintain the momentum until our network is completed,” said Matt Desch, Iridium’s CEO. “Even with this eight-week shift, SpaceX’s targeted schedule completes our constellation in mid-2018.”

The announcement came as the company successfully connected the first Iridium Next satellite via its crosslinks into its global low-Earth orbit constellation.

The new satellite is expected to begin providing service to Iridium customers in the coming days, signaling a major milestone for the Iridium Next program.

With a constellation of spacecraft orbiting Earth, Iridium provides mobile voice and data satellite communication anywhere on the globe.

Iridium officials said the testing and validation phase is ahead of schedule and the satellites are working well.

“Our team at our Satellite Network Operations Center has been working around-the-clock to confirm the health and performance of these new satellites,” said Scott Smith, Iridium’s chief operating officer.

Ten Iridium Next satellites were launched from Vandenberg Air Force Base on Jan. 14. In all, eight Falcon rocket flights are planned to lift 75 Iridum craft into space, with the next set for mid-June.Click to view larger
Ten Iridium Next satellites were launched from Vandenberg Air Force Base on Jan. 14. In all, eight Falcon rocket flights are planned to lift 75 Iridum craft into space, with the next set for mid-June. (SpaceX photo)

“Since their perfect orbit injection and deployment by SpaceX, our satellite testing process has progressed ahead of schedule, a testament to the rigorous development program they’ve undergone on the ground.”

In all, Iridium plans eight missions aboard SpaceX rockets, including the recently announced satellite rideshare with the joint NASA-German Research Center for Geosciences mission called Gravity Recovery and Climate Experiment Follow-On, or GRACE-FO.

On Jan. 31, Iridium said the twin satellites of the NASA/GFZ mission will share a rocket ride with the commercial communication craft although they will be deployed into a separate low-Earth orbit.

This will mark the first rideshare deal for Iridium, officials noted, adding that the company will be able to launch five additional satellites for its next-generation global satellite network.

The rideshare mission is expected to launch from Vandenberg in early 2018.

“This is a very smart way to get additional Iridium NEXT satellites into orbit,” Desch said. “This launch provides added resiliency to our network for not much more than we had planned originally to launch 72 satellites, including two with Kosmotras.”

Iridium initially hired the International Space Company Kosmotras to launch some satellites aboard the Dnepr rocket, until troubled relations between Ukraine and Russia essentially grounded the rocket.

In total, Iridium currently has plans to launch 75 Iridium Next satellites from Vandenberg — 66 to serve as operational satellites and nine as on-orbit spares.

The SpaceX backlog lessened by one with the successful launch from Florida of a Falcon rocket on Sunday from Florida.

Meanwhile, a United Launch Alliance Atlas V rocket with a top-secret payload is on track for a March 1 blastoff from Vandenberg’s Space Launch Complex-3.

A Falcon 9 rocket blasts off from Space Launch Complex-4 at Vandenberg Air Force Base on Jan. 14.Click to view larger

A Falcon 9 rocket blasts off from Space Launch Complex-4 at Vandenberg Air Force Base on Jan. 14. (SpaceX photo)
Quelle: Noozhawk

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Sonntag, 26. Februar 2017 - 18:15 Uhr

Astronomie - Ringförmige Sonnenfinsternis am 26.Februar 2017

25.02.2017

Die-hard eclipse chasers have journeyed to the Southern Hemisphere to catch a short and dramatically thin "ring" eclipse of the Sun.

Path of February 2017 annular eclipse

This month's annular solar eclipse is a far-southern event. Red lines show the moment of mid-eclipse in Universal Time; blue lines show the maximum fraction of the Sun's diameter covered by the Moon.
Sky & Telescope diagram; source: Fred Espenak

Whenever the Moon passes directly in front of the Sun, termed a central solar eclipse, we Earthlings usually conjure up visions of the awe and spectacle of totality.

But that's not always the case. The orbital geometry of the Earth-Moon system is subtle. At this time of year, Earth is relatively close to the Sun in its not-quite-circular obit, so the solar disk appears larger than average. And this coming weekend's new Moon is about midway between its perigee on February 18th and its apogee on March 3rd — so its disk won't be particularly large.

The upshot is that when the Moon and Sun meet in the sky on Sunday, February 26th, the result will be an annular or ring eclipse of the Sun. Astronomers calculate that the magnitude of this eclipse — the ratio of the Moon's apparent diameter to the Sun's — is 0.9922. So this event will be very nearly total and only barely annular. It'll be a dramatic sight along the centerline, as the ring at mid-eclipse will be no more than about 15 arcseconds wide!

This geometry also means that the path of annularity — called the antumbra — is very narrow, 31 km (19 miles) wide at the point of greatest eclipse though flaring to as much as 96 km (60 miles) at the endpoints. The culminating ring in this 3¼-hour-long event will last for at most 44 seconds.

Track of Feb. 2017's eclipse across South America

Many eclipse-chasers are traveling to southern Argentina, where the prospects for clear skies on eclipse day are most favorable.
Xavier Jubier

The eclipse will be confined almost entirely to the Southern Hemisphere. The path of annularity crosses parts of southern Chile and Argentina, the South Atlantic Ocean (where mid-eclipse occurs at 14:53 Universal Time), Angola, and (at sunset) the Zambia-Congo border.

Partial phases sweep over most of South America, Africa, and Antarctica, as the globe above shows. North Americans are left out entirely.

According to meteorologist Jay Anderson, the weather prospects in Africa are relatively poor. But they're much better in South America and especially over the flat Patagonian plains of southern Argentina, where the likelihood of a cloud-free morning is 60% or better. Not surprisingly, that's where most eclipse-chasers are headed.

So wish them all clear skies — and let's hope they take plenty of dramatic images of this celestial treat.

Check out Fred Espenak's website for more details.

Quelle: Sky&Telescope

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Rare "ring of fire" solar eclipse to give sky gazers a special treat Sunday

ringoffire

The sky will be illuminated in a “ring of fire” Sunday as the Earth welcomes its first solar eclipse of 2017.

An annular eclipse -- which occurs when the moon casts its shadow on the Earth’s surface, will mainly be visible above parts of the Southern Hemisphere, including Chile, Argentina and Angola, according to NASA

“An annular eclipse is the product of almost the same celestial geometry as a total solar eclipse -- that is, from the perspective of some place on Earth, the moon crosses in front of the sun’s center,” NASA explained in a blog.

During any type of solar eclipse, the sun, moon, and Earth line up. But an annual eclipse is different. The moon is too far from Earth to obscure the sun completely, leaving the sun’s edges exposed, thus creating that “ring of fire” effect.

Sky lovers who live in the Southern Hemisphere or near the equator can find an interactive map from NASA to search for partial eclipse times. If you live in North America, don’t worry, you’ll have a chance to catch another rare eclipse later this year.

On Aug. 21, less than six months from now, a total solar eclipse will cross the U.S. for the first time in nearly 40 years.

“The path of totality for the August eclipse runs from coast to coast,” NASA says.

During the total solar eclipse, the moon will completely cover the sun.

Either way, if you plan to watch any solar eclipse, NASA officials warn viewers to use protective eyeware. 

“Any time part, or all, of the sun’s surface is exposed – whether during an annular eclipse, a partial eclipse, or just a regular day -- it’s essential to use a proper solar filter or an indirect viewing method to view the sun,” NASA warns. “You can never look directly at the sun, and an annular eclipse is no exception!” 

Quelle: CBSN

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ANNULAR SOLAR ECLIPSE: Something strange is about to happen to sunbeams in the southern hemisphere. On Sunday, Feb. 26th, the Moon will pass in front of the sun, covering as much as 99% of the solar disk. It's an annular solar eclipse, shown here in an animation from ShadowandSubstance.com:

Annular eclipses occur when the Moon passes dead center in front of the sun, but does not completely cover it. At maximum eclipse, an intense "ring of fire" surrounds the mountainous limb of the Moon. 

The narrow path of annularity snakes across five countries: Chile and Argentina in South America; Angola, the Democratic Republic of the Congo, and Zambia in Africa. People in those countries can see the ring of fire for almost a minute and a half. Outside that path, the eclipse will be partial.  This means the sun will turn into a crescent—a slender one near the path of annularity and a fatter one away from it. Caution: Always use safe solar filters to observe the sun. 

Observers in the eclipse zone are encouraged to look down as well--for instance, at the sun-dappled ground beneath leafy trees.  The sight of a thousand crescent-shaped sunbeams swaying back and forth on a grassy lawn or sidewalk is unforgettable.

Quelle: Spaceweather

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Update: 26.02.2017

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LIVE-Frams von SoFi / 14.30 MEZ

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On Feb. 26, a “ring of fire” will be visible in the sky above parts of the Southern Hemisphere, including Chile, Argentina and Angola. This is called an annular eclipse.

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Quelle: NASA

 

 

 


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Sonntag, 26. Februar 2017 - 11:30 Uhr

Astronomie - Stammbaum der Sterne

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Mapping the family tree of stars 

Image showing a family trees of stars in our Galaxy, including the Sun

 

Astronomers are borrowing principles applied in biology and archaeology to build a family tree of the stars in the galaxy. By studying chemical signatures found in the stars, they are piecing together these evolutionary trees looking at how the stars formed and how they are connected to each other. The signatures act as a proxy for DNA sequences. It’s akin to chemical tagging of stars and forms the basis of a discipline astronomers refer to as Galactic archaeology.

 

The branches of the tree serve to inform us about the stars' shared history 

Dr Paula Jofré

It was Charles Darwin, who, in 1859 published his revolutionary theory that all life forms are descended from one common ancestor. This theory has informed evolutionary biology ever since but it was a chance encounter between an astronomer and an biologist over dinner at King’s College in Cambridge that got the astronomer thinking about how it could be applied to stars in the Milky Way.

Writing in Monthly Notices of the Royal Astronomical Society, Dr Paula Jofré, of the University of Cambridge’s Institute of Astronomy, describes how she set about creating a phylogenetic “tree of life” that connects a number of stars in the galaxy.

“The use of algorithms to identify families of stars is a science that is constantly under development. Phylogenetic trees add an extra dimension to our endeavours which is why this approach is so special. The branches of the tree serve to inform us about the stars’ shared history“ she says.

The team picked twenty-two stars, including the Sun, to study. The chemical elements have been carefully measured from data coming from ground-based high-resolution spectra taken with large telescopes located in the north of Chile. Once the families were identified using the chemical DNA, their evolution was studied with the help of their ages and kinematical properties obtained from the space mission Hipparcos, the precursor of Gaia, the spacecraft orbiting Earth that was launched by the European Space Agency and is almost halfway through a 5-year project to map the sky.

Stars are born from violent explosions in the gas clouds of the galaxy. Two stars with the same chemical compositions are likely to have been born in the same molecular cloud. Some live longer than the age of the Universe and serve as fossil records of the composition of the gas at the time they were formed.  The oldest star in the sample analysed by the team is estimated to be almost ten billion years old, which is twice as old as the Sun. The youngest is 700 million years old.

In evolution, organisms are linked together by a pattern of descent with modification as they evolve. Stars are very different from living organisms, but they still have a history of shared descent as they are formed from gas clouds, and carry that history in their chemical structure. By applying the same phylogenetic methods that biologists use to trace descent in plants and animals it is possible to explore the ‘evolution’ of stars in the Galaxy.

“The differences between stars and animals is immense, but they share the property of changing over time, and so both can be analysed by building trees of their history”, says Professor Robert Foley, of the Leverhulme Centre for Human Evolutionary Studies at Cambridge.

With an increasing number of datasets being made available from both Gaia and more advanced telescopes on the ground, and on-going and future large spectroscopic surveys, astronomers are moving closer to being able to assemble one tree that would connect all the stars in the Milky Way.

Paula Jofré et al. ‘Cosmic phylogeny: reconstructing the chemical history of the solar neighbourhood with an evolutionary tree’ is published by Monthly Notices of the Royal Astronomical Society. DOI 10.1093/mnras/stx075

Quelle: University of Cambridge


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Sonntag, 26. Februar 2017 - 11:15 Uhr

Astronomie - Was Radiostrahlung uns über die Sternentstehung in Spiralgalaxien verrät

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Sternenmusik aus fernen Galaxien

Was Radiostrahlung uns über die Sternentstehung in Spiralgalaxien verrät

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Ein Forscherteam unter der Leitung von Fatemeh Tabatabaei vom Instituto de Astrofisica de Canarias (IAC), mit Beteiligung von Astronomen von zwei Max-Planck-Instituten (MPIfR, Bonn und MPIA, Heidelberg), hat die Radiostrahlung einer großen Anzahl von 52 Galaxien jeweils bei mehreren Wellenlängen mit dem 100-m-Radioteleskop Effelsberg gemessen. Diese Galaxien wurden aus der sogenannten KINGFISH-Stichprobe ausgewählt, die Infrarot-Beobachtungen von Galaxien mit dem Satellitenteleskop „Herschel“ umfasst. Aus den Radiobeobachtungen konnte eine verlässliche Methode abgeleitet werden, die Sternentstehungsrate in Galaxien aus Radiobeobachtungen allein zu bestimmen, ohne Resultate aus anderen Spektralbereichen hinzuziehen zu müssen.

Fast alles Licht, das wir im Universum erblicken können, stammt von Sternen, die im Inneren von dichten Gaswolken im sogenannten interstellaren Medium von Galaxien geboren wurden. Die Häufigkeit ihrer Entstehung wird als Sternentstehungsrate bezeichnet. Sie hängt ab vom Gasvorrat in der Galaxie selbst sowie von physikalischen Eigenschaften wie Dichte, Temperatur und Stärke des Magnetfelds. Die Sternentstehungsrate stellt dabei eine Schlüsselgröße dar zum besseren Verständnis, wie Sternentstehung funktioniert.

Zur Bestimmung von Sternentstehungsraten kamen bis jetzt eine Reihe von Beobachtungen in ganz unterschiedlichen Wellenlängenbereichen zum Zuge, jeweils mit individuellen Vor- und Nachteilen. Licht im sichtbaren oder ultravioletten Spektralbereich kann zu einem erheblichen Teil durch interstellaren Staub absorbiert werden. Das führte zum Einsatz von hybriden Bestimmungsmethoden, die zwei oder mehr unterschiedliche Wellenlängenbereiche miteinander verknüpfen, darunter der Infrarotbereich, mit dessen Hilfe der Einfluss der Staubabsorption korrigiert werden kann. Dabei können aber wiederum andere Emissionsprozesse hineinspielen, die nicht mit der Entstehung von massereichen Sternen verknüpft sind und zu einer Konfusion der Ergebnisse führen können.

Ein internationales Forscherteam hat jetzt eine detaillierte Analyse der spektralen Energieverteilung  einer systematischen Stichprobe von Galaxien durchgeführt. Es handelt sich dabei um den überwiegenden Teil der in Abbildung 1 dargestellten Galaxien der KINGFISH-Studie. Die Astronomen konnten zum ersten Mal die abgestrahlte Energie dieser Galaxien im Radiofrequenzbereich bestimmen, aus der unmittelbar die Sternentstehungsraten folgen. „Wir haben dafür die gemessene Radiostrahlung in einem mittleren Frequenzbereich zwischen 1 und 10 GHz verwendet, da in früheren Untersuchungen eine eindeutige Korrelation zwischen Radio- und Infrarotstrahlung entdeckt wurde“, sagt Fatemeh Tabatabaei vom IAC (La Laguna, Teneriffa), die Erstautorin der vorliegenden Veröffentlichung. Es wurden detaillierte Untersuchungen durchgeführt, um die Energiequellen und die Prozesse in diesen Galaxien zu verstehen.

“Wir haben uns deshalb entschieden, systematische Radiobeobachtungen der Galaxien der KINGFISH-Stichprobe bei einer ganzen Reihe von Wellenlängen durchzuführen”, erinnert sich Eva Schinnerer vom Heidelberger Max-Planck-Institut für Astronomie (MPIA). „Als Einzelteleskop mit hoher Empfindlichkeit ist unser 100-m-Radioteleskop in Effelsberg das ideale Instrument, um verlässliche Radioflusswerte auch für schwache ausgedehnte Objekte wie diese Galaxien bestimmen zu können“, erklärt Marita Krause vom Bonner Max-Planck-Institut für Radioastronomie (MPIfR), die für die Radiomessungen der Galaxien mit dem 100-m-Teleskop verantwortlich war. „Wir haben es das KINGFISHER-Projekt genannt, wobei ‚KINGFISH galaxies Emitting in Radio‘ als Erklärung für das Acronym steht.“ Abbildung 2 zeigt die Radiostrahlung von einer der beobachteten Galaxien aus der Stichprobe (NGC 4725).

Die Ergebnisse des Projekts werden heute in der Fachzeitschrift “The Astrophysical Journal” veröffentlicht. Sie zeigen, dass die Radiostrahlung im beobachteten Wellenlängenbereich aus mehreren Gründen eine ideale Kenngröße zur Berechnung von Sternentstehungsraten der untersuchten Galaxien darstellt. Erstens findet keine Abschwächung der Strahlung durch Absorption im dazwischenliegenden interstellaren Staub statt. Zweitens wird Radiostrahlung bei massereichen Sternen in mehreren Phasen ihrer Entstehung abgestrahlt, von jungen stellaren Objekten über HII-Regionen (Gebiete mit ionisiertem Gas) bis hin zu Supernova-Überresten. Und schließlich ist es auch nicht notwendig, die gefundene Messgröße mit Ergebnissen aus anderen Wellenlängenbereichen zu korrigieren.  Aus all diesen Gründen stellen Messungen im untersuchten Radiowellenlängenbereich einen eindeutigeren Weg zur Bestimmung der Sternentstehungsrate von Galaxien dar als viele der bislang benutzten Methoden.

“Wir können jetzt daran gehen, mit Hilfe von Messungen am Radioteleskop Effelsberg diese Methode auf eine ganze Reihe weiterer Galaxien anzuwenden“, schließt  Rainer Beck vom MPIfR, ebenfalls Ko-Autor der vorliegenden Untersuchung.

 

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<p><em>Spiralgalaxie NGC 4725. Die Konturlinien zeigen Radiokontinuumsstrahlung bei einer Frequenz von 8,5 GHz, gemessen mit dem 100-m-Radioteleskop Effelsberg, überlagert auf eine optische Aufnahme der Galaxie.</em></p>
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<em><br /> <br /> </em>Bild vergrößern

Spiralgalaxie NGC 4725. Die Konturlinien zeigen Radiokontinuumsstrahlung bei einer Frequenz von 8,5 GHz, gemessen mit... [mehr]

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Das Autorenteam umfasst F.S. Tabatabaei, E. Schinnerer, M. Krause, G. Dumas, S. Meidt, A. Damas-Segovia, R. Beck, E.J. Murphy, D.D. Mulcahy, B. Groves, A. Bolatto, D. Dale, M. Galametz, K. Sandstrom, M. Boquien, D. Calzetti, R.C. Kennicutt, L.K. Hunt, I. de Looze und E.W. Pellegrini. Vom MPIfR beteiligte Autoren sind Marita Krause, Ancor Damas-Segovia und Rainer Beck.

Fatemeh Tabatabaei hat die Erforschung der Radio- und Ferninfrarotstrahlung von Galaxien im Verlauf ihrer Promotion am MPIfR begonnen und später als Postdoc am MPIfR Bonn und am MPIA Heidelberg fortgesetzt. Zur Zeit ist sie als Wissenschaftlerin am Instituto de Astrofisica de Canarias (IAC), La Laguna, tätig.

Das KINGFISH-Projekt (“Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel”) ist eine systematische Studie von insgesamt 61 Galaxien im nahen Universum. KINGFISHER (“KINGFISH galaxies Emitting in Radio”) stellt eine Untergruppe dieser Galaxien dar, die nördlich von -21 Grad Deklination liegen und somit von Effelsberg aus beobachtbar sind. Für 17 dieser Galaxien existierten bereits im Vorfeld Radiobeobachtungen in mehreren Frequenzen mit dem 100-m-Radioteleskop Effelsberg (vgl. die Website „Atlas of Galaxies“). 35 weitere Galaxien wurden mit dem 100-m-Teleskop neu beobachtet. Beide Datensätze mit insgesamt 52 Galaxien wurden im Rahmen der vorliegenden Studie ausgewertet.

Quelle: Max-Planck-Institut für Radioastronomie, Bonn


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Sonntag, 26. Februar 2017 - 11:00 Uhr

Raumfahrt - AMERICA’S GATEWAY TO SPACE: LC-39A

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Artist’s illustration of Launch Complex 39 with proposed Pads 39A, 38C and 39C. Also shown are the VAB, LCC and the 130-foot wide crawlerway. Credit: NASA via Retro Space Images.

The iconic launch pads, Pads 39A and 39B at Kennedy Space Center’s Launch Complex 39, have been the starting point for many space flights including the first manned lunar landing. The original design for Launch Complex 39 called for three to five launch pads, designated 39A – 39E, that would have been spaced approximately 1.6 miles apart to protect them from damage if any mishaps occurred at an adjacent pad. Also part of Launch Complex 39 is the Vehicle Assembly Building, or VAB. Towering more than 500 feet, it can be seen easily from miles away. The Launch Control Center, or LCC, where all the launch controllers, support personnel, and equipment required to safely launch a vehicle from either of the launch pads is also a part of the large complex.

Aerial view of Launch Complex 39A during construction in the 1960s. Credit: NASA

PAD 39A FROM SAND TO APOLLO

Pad 39A was originally designated to be Pad 39C in the complex’s original plan, however it became 39A when plans to build the three additional pads were scrapped in 1963. Launch Complex 39’s A pad was completed first. Construction began in November of 1963 and was completed in early September 1965. Built on around a quarter square mile of land, the launch site is an eight sided polygon and measures 3,000 feet across. The pad itself is 390 feet by 325 feet and is constructed of reinforced concrete. The hardstand stands 48 feet above sea level. To get from sea level up to the hard stand, a five-percent sloped ramp was constructed. Which raises the question, “Why build up and not down to avoid having to have a ramp up to the pad?”. The answer is simple, the pads are located in Florida just a quarter mile away from the Atlantic Ocean, and digging down just a few feet you will encounter water. So to protect all the equipment and facilities that are under the pad, the decision to build above ground was made.

Aerial views of Launch Complex 39A during construction in August of 1965. Credit: NASA via Retro Space Images.

For Apollo, the pad would be a clean pad, no structure, towers, or other support equipment was located on top of the pad. All these items would be brought with the vehicle. The vehicle was assembled on a massive platform known as a Mobile Launcher. On the Mobile Launcher was a Launch Umbilical Tower (LUT) and a mobile service structure which allowed for crew access, all the umbilical connections for the rocket, elevators, service platforms, everything you needed to get the vehicle ready for launch on the pad. The Mobile Launcher was transported by a new vehicle, called the Crawler, from the Vehicle Assembly Building out to the pad. The Mobile launcher would be lowered onto pedestals located atop the hardstand.

Aerial views of Launch Complex 39A during construction in November of 1965. Credit: NASA via Retro Space Images.

Without the Mobile Launcher at the pad, from the outside mostly what you see at Pad 39A is the pad itself, however much more lies beneath the exterior. A two-story pad terminal connection room which houses all of the electronic equipment that would connect the Launch Control Center with the Mobile Launcher when it’s on the pad, is located on the western side of the pad. Also on the same side is the environmental control systems room which supports the air conditioning and water systems. Beneath the east side of the pad is the high-pressure-gas storage facility, where nitrogen and helium gases piped from the converter-compressor facility would be distributed from. Dissecting the east and west sides is the 58 foot wide, 450 foot long, Flame Trench. A Flame Deflector, weighing some 700 tons, would be rolled into place via a rail system in the Flame Trench until it was just under the rocket. The deflector directed the flames down the trench and away from the vehicle and pad.

Aerial view of Launch Pad 39A during the Apollo/Saturn era. Credit: NASA

Also located inside of the pad area is a blast room. If a hazardous condition came up that required the Apollo Astronauts to egress from the spacecraft, they would move from the spacecraft back to the Mobile Launcher’s tower and ride the high speed elevator down 30 stories, in about 30 seconds. Then they would slide down an escape tube to the blast room. The blast room has thick steel doors which could withstand the explosion if the vehicle erupted on the pad. The crew could survive for at least 24 hours in the blast room until they could be rescued.

A Saturn V rocket atop Launch Pad 39A with the fixed and mobile service structures in place. Credit: NASA

The first flight from Pad 39A would be Apollo 4, an unmanned test of the great Saturn V rocket. Following it would be another unmanned test, Apollo 6. The third launch was the historic first trip to the moon, Apollo 8, which took Frank Borman, Jim Lovell, and Bill Anders on a trip to the moon where they did 10 orbits before coming back to Earth. And the fifth launch from Pad 39A would be Apollo 11, the first manned Lunar landing when Neil Armstrong and Buzz Aldrin became the first human beings to step on another space body. Pad 39A would be the starting point for every Saturn V mission except for Apollo 10 which launched from Pad 39B. Twelve flights of the Saturn V started at Pad 39A and half of them were the manned lunar landing missions. The pad’s significance as a historical landmark will never be in question due to the fact the first manned landing missions to the Moon all began there. It also served as the launch pad for the Skylab orbiting outpost – our first space station – which was also the last flight of the Saturn V rocket and the last mission to launch from Pad 39A for more than six years.

The Apollo 11 Saturn V lifts off with Neil Armstrong, Michael Collins and Buzz Aldrin on July 16, 1969. Credit: NASA

Looking like a giant erector set, Launch Pad 39A underwent major renovation in the 1970s to evolve it from the Apollo era ‘clean’ pad to include more fixed structures to support Space Shuttle launches. Credit: NASA

FROM APOLLO TO SPACE SHUTTLE

Shortly after Skylab launched, modifications to the pad began for the next step in our continuing exploration of space. The Space Shuttle program had been approved before the Apollo missions were even finished. In fact, Apollo 16 Commander John Young and his Lunar Module Pilot Charlie Duke were walking on the surface when word came up from Mission Control that the budget had passed, including the vote for the Space Shuttle program.

Launch Pad 39A undergoing modification, including ground word, during 1979. Credit: NASA via Retro Space Images

The Shuttle would be a totally different vehicle than the mighty Saturn V and Saturn 1B rockets that had flown from Launch Complex 39 up until now. While the new vehicle would be less than two thirds the height of the Saturn V, its design required a complete reconfiguration of the Pad structure and the mobile launcher. A lot of work on the ground had to take place before the Shuttle would ever fly.

Pad 39A undergoing significant modification to accommodate the Space Shuttle program during 1978. Credit: NASA via Retro Space Images

The pad would now be the permanent site for the umbilical tower, or as it was now called the Fixed Service Structure (FSS). This was not a completely new structure however, the upper portion of Launch Umbilical Tower (LUT) that Apollo used was removed from the Mobile Platform and installed on the Launch Pad 39A’s hardstand to become the FSS. Standing 347 feet high, the new FSS would have 12 floors, 20 feet apart. Each floor is actually not solid, but metal grates, so looking down at your feet you can actually see down a number of floors. The exception is the 195 foot level where the crew accesses the orbit, it has solid floors because, well you’ll find out later in the story. It had three access arms that provided services or access to the Shuttle. On top of the structure was a new 80 foot tall lightning mast, and just below the mast, an Apollo era Hammerhead crane was installed to be used for any heavy lifting operations needed at the pad. The crane was removed in 1994 when cost analysis revealed it to be more cost effective to bring in mobile cranes when needed rather than to maintain the hammerhead crane.

Closeup view of Launch Pad 39A showing both Service Structures, the Flame Trench and a MLP with Atlantis atop it. Credit: Chase Clark

Located between the 207 foot and 227 foot level of the FSS was the Gaseous Oxygen Vent Arm. On the end of that arm was a 13 foot diameter hood, known as the “Beanie Cap”. The cap would heat gaseous oxygen that vented from the Shuttle’s External Tank that could freeze and form potentially dangerous ice. The oxygen travels just a few feet away from the hood where it is safely released into the atmosphere. The arm would be in place before fueling and would be swung away approximately 2.5 minutes prior to launch.

The Beanie Cap served an important purpose – preventing extremely cold oxygen that vented from the External Tank from turning into ice and potentionally damaging the launch vehicle. Credit: Chase Clark

Headed down the FSS, we next find the External Tank Hydrogen Vent Umbilical and Intertank Access Arm located at the 167 foot level. The 48 foot long arm gives the pad crew access to the External Tank intertank compartment if needed. It also allows for mating of the External Tank umbilical and vent lines. Around 5 days prior to launch, the arm is retracted leaving just the umbilical vent line connected to the External Tank to support tanking and launch. The vent line part of the umbilical serves basically the same purpose as the Beanie Cap, except venting hydrogen from the tank. Also rather than releasing the hydrogen close by, it is taken through the line, into a venting system that takes it far away from the pad where it is safely burned off. The line itself detaches at first motion of the vehicle at launch and is pulled away downward away from the vehicle and secured.

Finally at the 147 foot level you would find the Orbiter Access Arm. At 65 feet long, 5 foot wide, and 8 feet high, it’s the largest arm on the FSS. This metal bridge provides access to the crew compartment of the orbiter. Located at the end of the arm is the “White Room,” an environmentally controlled chamber which mates with the orbiter and can hold up to six people. After the crew is loaded and all the pad personnel have left, the arm remains in place until 7 minutes and 24 seconds prior to the launch to serve as an emergency escape if needed. After that time it can be repositioned in about 15 seconds if any emergency arises.

The Mobile Launch Platforms have served both the Apollo and Space Shuttle programs, and have undergone renovation to also be used for the SLS program. Credit: NASA

Fueling of the Shuttle required a lot of propellant as the External Tank held over 500,000 gallons of propellants. Two spheres on opposite sides of the pad perimeter, approximately 3,000 feet apart, held the propellants until they were pumped into the Shuttle’s External Tank. One tank could hold up to 900,000 gallons of liquid oxygen at –297 degrees Fahrenheit while the other tank could hold 850,000 gallons of liquid hydrogen at –423 degrees Fahrenheit. The propellants were transferred from the storage tanks in vacuum-jacketed lines that feed into the orbiter and External Tank via the tail service masts on the mobile launcher platform.

The Apollo blast room was mothballed and instead a new Emergency Egress System was installed. The new system was located at the 195 level of the FSS, the same height as the Crew Access Arm, and is a slide wire system with baskets for astronauts and pad workers to speedily escape the pad in the event of an emergency. In 135 launches, the system was never used, however if it had been, fire nozzles would release heavy sprays of water over the pad area. Remember earlier I mentioned how the 195 foot level had a solid floor? The water spray would be so heavy that the crew and pad personnel would only be able to see their feet and the floor, so a bright yellow pathway was painted on the floor, sometimes humorously referred to by the pad and crew as the Yellow Brick road, this would lead them to the escape baskets.

At the slidewire basket landing area, STS-116 crew members sit in one of the baskets used for emergency egress away from the launch pad. From left are Pilot William Oefelein and Mission Specialists Joan Higginbotham and Christer Fuglesang. Credit: NASA/Kim Shiflett

Seven baskets and slide wires were in place, each basket capable of transporting three people to the ground some 1200 feet to the west of the pad in just 90 seconds. The basket would reach a top speed of 55 MPH and would be slowed by a drag chain before coming to a complete stop in the catch net at the end of the system. When reaching the ground, the crew and pad personnel would find a bunker and one or more M-113 Armored Vehicles. In the event of an imminent detonation, the bunker could provide the best protection; otherwise they would board the M-113 Armored Vehicles and make a hasty departure to a safe zone more than a mile away from the pad.

Crew members of space shuttle Discovery’s STS-133 mission ride in an M-113 armored personnel carrier, which is kept at the foot of the launch pad in case of an emergency. Credit: NASA

Another addition to the pad would be the Sound Suppression Water System. With the orbiter so close to the Mobile launcher, the sound waves produced by the three Space Shuttle Main Engines and the massive Solid Rocket Boosters upon ignition could have possibly damaged anything in the orbiter’s cargo bay and possibly the orbiter itself. The solution was to reduce the sound waves with a flow of water over the Mobile Launch Platform and the pad itself. A 300,000 gallon water tank located on the northeast side of the pad contains the water used in the system. Using gravity alone, the water is dumped onto the MLP and the Flame Trench of the pad via a system of quench nozzles, also known as “rainbirds”. When a Shuttle would launch, the intense heat from the engines would turn much of the water into steam, resulting in the large white cloud seen around the pad prior to booster ignition.

Attached to the FSS is the Rotating Service Structure or RSS. The main purpose of the RSS is to allow installation and servicing of the Shuttle’s payload for that mission, at the pad. It also allows technicians access to certain systems on the orbiter. A typical Shuttle launch begins a month or so prior to liftoff when the Shuttle, aboard the Mobile Launch Platform, is moved to the pad. Having payload installation at the pad allows the payload to be loaded much further along in the launch processing.

Measuring in at a healthy 102 feet long, by 50 feet wide, and 130 feet high, the RSS is quite a sight on its own. It rotates 120 degrees and is moved away from the Shuttle well before fueling and launch. The Payload Changeout Room is the main feature of the RSS. It’s an environmentally controlled area that is enclosed and supports the delivery of the payload to the orbiter’s payload bay. Also if the payload requires any servicing at the pad it is performed there. Inside there are five platform levels that allow access to the payload.

The exhaust plume from Space Shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from NASA’s Florida spaceport on July 8, 2011. Credit: NASA/Dick Clark

Two other parts of the RSS, the Orbiter Midbody Umbilical Unit, and the Hypergolic Umbilical unit, provide access and service to two important areas of the orbiter. The first provides fluids to the orbiter’s reactant storage and distribution system as well as fuel for the orbiter’s three fuel cells. The Hypergolic Umbilical Unit supplies Hypergolic fuel and oxygen service lines along with helium and nitrogen service lines which supply the orbiter’s Orbital Maneuvering System (OMS) pods.

Of the 135 Space Shuttle missions, Pad 39A served as the launch pad for 80 of them, including the first mission, STS-1, and the last mission, STS-135.

Space Shuttle Columbia arrives at Launch Pad 39A on Dec. 29, 1980, in preparation for its maiden liftoff on April 12, 1981. Credit: NASA

OTHER NOTABLE SPACE SHUTTLE MISSIONS TO LAUNCH FROM PAD 39A

• STS-7, which carried Sally Ride, the first female American Astronaut into orbit

• STS-41c, the first mission to retrieve, repair, and re-deploy a satellite (SolarMax)

• STS-82 – the second Hubble Space Telescope servicing mission

• STS-103 – the third Hubble Space Telescope servicing mission

• STS-109 – the fourth Hubble Space Telescope servicing mission (The last successful mission by Columbia)

• STS-125 – the fifth and final Hubble Space Telescope servicing mission

• Also many of the International Space Station assembly missions, Spacehab missions, and Shuttle/Mir docking missions were launched from Pad 39A. Pad 39A saw the last launch of every orbiter except for Challenger.

Space Shuttle Atlantis is seen as it lifts off from Kennedy Space Center to begin the STS-132 mission on May 14, 2010. Credit: Chase Clark

PAD 39A MOVES FROM NASA TO COMMERCIAL PROVIDERS

After the Shuttle program ended, NASA turned its attention to its next vehicle, the Space Launch System. A new rocket, derived from the Shuttle legacy which would launch humans beyond Earth orbit for the first time in over 40 years. This new vehicle would, like the Saturn V, bring all its support equipment with it to the pad, so the pad would once again be a clean pad. Work on Pad 39B to return it to a clean pad began before the Shuttle program had even ended. With a low flight rate, and a full Mobile Launcher being used to launch the new rocket, NASA determined in December of 2013 that it would only use Pad 39B and the decision to lease Pad 39A to one of the commercial providers was made.

SpaceX was awarded the use of the iconic launch pad and signed a 20 year lease in April of 2014. Since that time SpaceX has already began modifications to the pad area including the construction of a new Horizontal Integration Facility where processing of their boosters and some payload integration will occur. SpaceX is looking at also doing payload integration vertically now as that is a requirement of getting contracts with the U.S. Air Force for launches. The new building is located alongside the crawlerway just before the incline to the hard stand.

The Flame Trench has been modified to accommodate Falcon 9 launches as well. The south side of the Flame Trench was completely filled in; all exhaust from the Falcon 9 launches will be directed out the north end of the trench via the Flame Deflector. That side has been resurfaced with refractory concrete to withstand the intense heat of launches.

A Falcon 9 rocket lifts off from the historic LC-39A launch pad – the first commercial rocket to ever do so – to begin the CRS-10 mission to the ISS. Credit: SpaceX

The Fixed Service Structure from the Space Shuttle program will be left in place for now. Modifications to accommodate crewed missions and access to the Dragon capsule will be made in the future. The Crew Access Arm from the Shuttle era was removed by NASA, presumably to be preserved for a museum or space facility to display.

New kerosene storage tanks have already been installed on the northeast side of the pad, the Falcon burns rocket grade kerosene (RP-1)and liquid oxygen (LOX), and SpaceX plans to utilize the liquid oxygen tank used by the Shuttle program for their LOX.

 

 

Falcon 9 rockets are moved horizontally to the pad on what is called a Transporter/Erector. Rails have been installed from the HIF up to the hard stand to guide the Transporter/Erector to the pad. SpaceX recently tested the new Transporter/Erector at Pad 39A.

Launching of the Falcon Heavy from Pad 39A has been delayed numerous times over the past year and a half, however Pad 39A was returned to active use recently with the successful launch of the Falcon 9 rocket on Sunday, February 19 on the CRS-10 resupply mission to the International Space Station.

Later this decade, crewed missions once again will blast off from the historic pad. Initially just to the ISS, but SpaceX also has set its sight on establishing a colony on Mars beginning as soon as the following decade.

View of the CRS-10 launch from atop the VAB at Kennedy Space Center. Credit: Julian Leek

Quelle: RocketSTEM


783 Views

Sonntag, 26. Februar 2017 - 08:30 Uhr

Astronomie - Neuer Atomteilchenbeschleuniger bei Lockheed Martin Lab im Silicon Valley (SPARC)

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New Lockheed Martin Lab in Silicon Valley "SPARC"s Interest in Space Science
Atomic particle accelerator--one of only a few in the world--brings new capability to Silicon Valley's space industry
Lockheed Martin’s new Space Plasma and Radiation Center (SPARC) features one of the world’s few atomic particle accelerators that the facility will use to mimic the sun’s effects on space instruments. 

PALO ALTO, Calif.Feb. 21, 2017 /PRNewswire/ -- What sounds like science fiction is now reality for a new Lockheed Martin (NYSE: LMT) laboratory in Silicon Valley. Technicians from Denmark installed a new linear particle accelerator at the company's Advanced Technology Center to cap a significant expansion in space instrument testing. The accelerator, one of a few in the world, is part of a collection of new testing hardware designed to take spacecraft to new levels of capability and performance.

"Before we send new materials and instruments into orbit, we must first ensure they will survive the brutal environment of space," said David Knapp, lead scientist for the Space Plasma and Radiation Center (SPARC). "So we replicate the space environments in vacuum chambers here on Earth and analyze the results."

The SPARC encompasses 1,800 square feet and includes new hardware to test sensitive instruments that range from space-based imaging and communications satellites to deep space navigation.

The testing machines are extremely precise. For example, the particle accelerator speeds protons to over 12 million miles per hour, or 2 percent the speed of light. The electron accelerator shoots electrons to 66 percent the speed of light, and the solar simulator delivers 2.5 suns worth of light exposure. All the instruments are precisely positioned to less than 100 microns, many times smaller than the width of a human hair.

Equipment in the center includes the particle accelerator, electron accelerator, solar simulators, UV arc lamps, electrostatic discharge equipment, reflectance measurement probes, residual gas analyzer, precision motion stages, liquid and nitrogen cooling. The facility also incorporates large 5ftx10ft vacuum chambers for flexible testing.

About Lockheed Martin
Headquartered in Bethesda, Maryland, Lockheed Martin is a global security and aerospace company that employs approximately 97,000 people worldwide and is principally engaged in the research, design, development, manufacture, integration and sustainment of advanced technology systems, products and services.

Quelle: Lockheed Martin


673 Views

Sonntag, 26. Februar 2017 - 08:15 Uhr

Astronomie - Der glühende Nebel im Herzen eines riesigen Protoclusters von frühen Galaxien

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Vast luminous nebula poses a cosmic mystery

Glowing nebula found at the heart of a huge "protocluster" of early galaxies appears to be part of the cosmic web of filaments connecting galaxies, but what's lighting it up?

lya-nebula-410.jpg

MAMMOTH-1 is an extended blob of gas in the intergalactic medium called an enormous Lyman-alpha nebula (ELAN). The color map and contours denote the surface brightness of the nebula, and the red arrows show its estimated spatial extent. (Image credit: Figure 2 of Cai et al., Astrophysical Journal)

Astronomers have found an enormous, glowing blob of gas in the distant universe, with no obvious source of power for the light it is emitting. Called an "enormous Lyman-alpha nebula" (ELAN), it is the brightest and among the largest of these rare objects, only a handful of which have been observed.

ELANs are huge blobs of gas surrounding and extending between galaxies in the intergalactic medium. They are thought to be parts of the network of filaments connecting galaxies in a vast cosmic web. Previously discovered ELANs are likely illuminated by the intense radiation from quasars, but it's not clear what is causing the hydrogen gas in the newly discovered nebula to emit Lyman-alpha radiation (a characteristic wavelength of light absorbed and emitted by hydrogen atoms).

The newly discovered nebula was found at a distance of 10 billion light years in the middle of a region with an extraordinary concentration of galaxies. Researchers found this massive overdensity of early galaxies, called a "protocluster," through a novel survey project led by Zheng Cai, a Hubble Postdoctoral Fellow at UC Santa Cruz.

"Our survey was not trying to find nebulae. We're looking for the most overdense environments in the early universe, the big cities where there are lots of galaxies," said Cai. "We found this enormous nebula in the middle of the protocluster, near the peak density."

MAMMOTH survey

Cai is first author of a paper on the discovery accepted for publication in the Astrophysical Journal and available online. His survey project is called Mapping the Most Massive Overdensities Through Hydrogen(MAMMOTH), and the newly discovered ELAN is known as MAMMOTH-1.

Coauthor J. Xavier Prochaska, professor of astronomy and astrophysics at UC Santa Cruz, said previously discovered ELANs have been detected in quasar surveys. In those cases, the intense radiation from a quasar illuminated hydrogen gas in the nebula, causing it to emit Lyman-alpha radiation. Prochaska's team discovered the first ELAN, dubbed the "Slug Nebula," in 2014. MAMMOTH-1 is the first one not associated with a visible quasar, he said.

"It's extremely bright, and it's probably larger than the Slug Nebula, but there's nothing else visible except the faint smudge of a galaxy. So it's a terrifically energetic phenomenon without an obvious power source," Prochaska said.

Equally impressive is the enormous protocluster in which it resides, he said. Protoclusters are the precursors to galaxy clusters, which consist of hundreds to thousands of galaxies bound together by gravity. Because protoclusters are spread out over a much larger area of the sky, they are much harder to find than galaxy clusters.

The protocluster hosting the MAMMOTH-1 nebula is massive, with an unusually high concentration of galaxies in an area about 50 million light years across. Because it is so far away (10 billion light years), astronomers are in effect looking back in time to see the protocluster as it was 10 billion years ago, or about 3 billion years after the big bang, during the peak epoch of galaxy formation. After evolving for 10 billion more years, this protocluster would today be a mature galaxy cluster perhaps only one million light years across, having collapsed down to a much smaller area, Prochaska said.

Cosmic web

The standard cosmological model of structure formation in the universe predicts that galaxies are embedded in a cosmic web of matter, most of which is invisible dark matter. The gas that collapses to form galaxies and stars traces the distribution of dark matter and extends beyond the galaxies along the filaments of the cosmic web. The MAMMOTH-1 nebula appears to have a filamentary structure that aligns with the galaxy distribution in the large-scale structure of the protocluster, supporting the idea that ELANs are illuminated segments of the cosmic web, Cai said.

"From the distribution of galaxies we can infer where the filaments of the cosmic web are, and the nebula is perfectly aligned with that structure," he said.

Cai and his coauthors considered several possible mechanisms that could be powering the Lyman-alpha emission from the nebula. The most likely explanations involve radiation or outflows from an active galactic nucleus (AGN) that is strongly obscured by dust so that only a faint source can be seen associated with the nebula. An AGN is powered by a supermassive black hole actively feeding on gas in the center of a galaxy, and it is usually an extremely bright source of light (quasars being the most luminous AGNs in visible light).

The intense radiation from an AGN can ionize the gas around it (called photoionization), and this may be one mechanism at work in MAMMOTH-1. When ionized hydrogen in the nebula recombines it would emit Lyman-alpha radiation. Another possible mechanism powering the Lyman-alpha emissions is shock heating by a powerful outflow of gas from the AGN.

The researchers described several lines of evidence supporting the existence of a hidden AGN energizing the nebula, including the dynamics of the gas and emissions from other elements besides hydrogen, notably helium and carbon.

"It has all the hallmarks of an AGN, but we don't see anything in our optical images. I expect there's a quasar that is so obscured by dust that most of its light is hidden," Prochaska said.

In addition to Cai and Prochaska at UC Santa Cruz, the team includes coauthors at Steward Observatory, University of Arizona; Korea Astronomy and Space Institute; Mount Stromlo Observatory, Australia; Pontifical Catholic University of Chile; Institute for Astronomy, ETH Zurich; California Institute of Technology; Kavli Institute for Astronomy and Astrophysics, Peking University; and National Astronomical Observatory of Japan. This research was supported by the National Science Foundation and NASA.

Quelle: UC SANTA CRUZ


648 Views

Sonntag, 26. Februar 2017 - 08:00 Uhr

Astronomie - Der Beginn einer neuen Ära für Supernova 1987A

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The Dawn of a New Era for Supernova 1987A
 
The Dawn of a New Era for Supernova 1987A
 
 

In February 1987, on a mountaintop in Chile, telescope operator Oscar Duhalde stood outside the observatory at Las Campanas and looked up at the clear night sky. There, in a hazy-looking patch of brightness in the sky — the Large Magellanic Cloud (LMC), a neighboring galaxy - was a bright star he hadn't noticed before.

That same night, Canadian astronomer Ian Shelton was at Las Campanas observing stars in the Large Magellanic Cloud. As Shelton was studying a photographic plate of the LMC later that night, he noticed a bright object that he initially thought was a defect in the plate. When he showed the plate to other astronomers at the observatory, he realized the object was the light from a supernova. Duhalde announced that he saw the object too in the night sky. The object turned out to be Supernova 1987A, the closest exploding star observed in 400 years. Shelton had to notify the astronomical community of his discovery. There was no Internet in 1987, so the astronomer scrambled down the mountain to the nearest town and sent a message to the International Astronomical Union's Bureau for Astronomical Telegrams, a clearing house for announcing astronomical discoveries.

Since that finding, an armada of telescopes, including the Hubble Space Telescope, has studied the supernova. Hubble wasn't even in space when SN 1987A was found. The supernova, however, was one of the first objects Hubble observed after its launch in 1990. Hubble has continued to monitor the exploded star for nearly 30 years, yielding insight into the messy aftermath of a star's violent self-destruction. Hubble has given astronomers a ring-side seat to watch the brightening of a ring around the dead star as the supernova blast wave slammed into it.

 
Release ID: STScI-2017-08
Release images (8)
Hubble Captures Wide View of Supernova 1987A
Release videos (5)
Hubble Chronicles Brightening of Ring around an Exploded Star
Tags
 
 
The Full Story
Release date: Feb 24, 2017
The Dawn of a New Era for Supernova 1987A

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.

Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.

To commemorate the 30th anniversary of SN 1987A, new images, time-lapse movies, a data-based animation based on work led by Salvatore Orlando at INAF-Osservatorio Astronomico di Palermo, Italy, and a three-dimensional model are being released. By combining data from NASA's Hubble Space Telescope and Chandra X-ray Observatory, as well as the international Atacama Large Millimeter/submillimeter Array (ALMA), astronomers — and the public — can explore SN 1987A like never before.

Hubble has repeatedly observed SN 1987A since 1990, accumulating hundreds of images, and Chandra began observing SN 1987A shortly after its deployment in 1999. ALMA, a powerful array of 66 antennas, has been gathering high-resolution millimeter and submillimeter data on SN 1987A since its inception. 

"The 30 years' worth of observations of SN 1987A are important because they provide insight into the last stages of stellar evolution," said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, and the Gordon and Betty Moore Foundation in Palo Alto, California.

The latest data from these powerful telescopes indicate that SN 1987A has passed an important threshold. The supernova shock wave is moving beyond the dense ring of gas produced late in the life of the pre-supernova star when a fast outflow or wind from the star collided with a slower wind generated in an earlier red giant phase of the star's evolution. What lies beyond the ring is poorly known at present, and depends on the details of the evolution of the star when it was a red giant.

"The details of this transition will give astronomers a better understanding of the life of the doomed star, and how it ended," said Kari Frank of Penn State University who led the latest Chandra study of SN 1987A.

Supernovas such as SN 1987A can stir up the surrounding gas and trigger the formation of new stars and planets. The gas from which these stars and planets form will be enriched with elements such as carbon, nitrogen, oxygen, and iron, which are the basic components of all known life. These elements are forged inside the pre-supernova star and during the supernova explosion itself, and then dispersed into their host galaxy by expanding supernova remnants. Continued studies of SN 1987A should give unique insight into the early stages of this dispersal.

Some highlights from studies involving these telescopes include:

Hubble studies have revealed that the dense ring of gas around the supernova is glowing in optical light, and has a diameter of about a light-year. The ring was there at least 20,000 years before the star exploded. A flash of ultraviolet light from the explosion energized the gas in the ring, making it glow for decades.

The central structure visible inside the ring in the Hubble image has now grown to roughly half a light-year across. Most noticeable are two blobs of debris in the center of the supernova remnant racing away from each other at roughly 20 million miles an hour. 

From 1999 until 2013, Chandra data showed an expanding ring of X-ray emission that had been steadily getting brighter. The blast wave from the original explosion has been bursting through and heating the ring of gas surrounding the supernova, producing X-ray emission.

In the past few years, the ring has stopped getting brighter in X-rays. From about February 2013 until the last Chandra observation analyzed in September 2015 the total amount of low-energy X-rays has remained constant. Also, the bottom left part of the ring has started to fade. These changes provide evidence that the explosion's blast wave has moved beyond the ring into a region with less dense gas. This represents the end of an era for SN 1987A.

Beginning in 2012, astronomers used ALMA to observe the glowing remains of the supernova, studying how the remnant is actually forging vast amounts of new dust from the new elements created in the progenitor star. A portion of this dust will make its way into interstellar space and may become the building blocks of future stars and planets in another system.

These observations also suggest that dust in the early universe likely formed from similar supernova explosions.

Astronomers also are still looking for evidence of a black hole or a neutron star left behind by the blast. They observed a flash of neutrinos from the star just as it erupted. This detection makes astronomers quite certain a compact object formed as the center of the star collapsed — either a neutron star or a black hole — but no telescope has uncovered any evidence for one yet.

These latest visuals were made possible by combining several sources of information including simulations by Salvatore Orlando and collaborators that appear in this paper: https://arxiv.org/abs/1508.02275. The Chandra study by Frank et al. can be found online at http://lanl.arxiv.org/abs/1608.02160. Recent ALMA results on SN 87A are available at https://arxiv.org/abs/1312.4086

The Chandra program is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

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

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ.

Quelle: NASA

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Update: 26.02.2017

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The Dawn of a New Era for Supernova 1987A

Three decades ago, astronomers spotted one of the brightest exploding stars in more than 400 years. The titanic supernova, called Supernova 1987A (SN 1987A), blazed with the power of 100 million suns for several months following its discovery on Feb. 23, 1987.

Since that first sighting, SN 1987A has continued to fascinate astronomers with its spectacular light show. Located in the nearby Large Magellanic Cloud, it is the nearest supernova explosion observed in hundreds of years and the best opportunity yet for astronomers to study the phases before, during, and after the death of a star.

To commemorate the 30th anniversary of SN 1987A, new images, time-lapse movies, a data-based animation based on work led by Salvatore Orlando at INAF-Osservatorio Astronomico di Palermo, Italy, and a three-dimensional model are being released. By combining data from NASA’s Hubble Space Telescope and Chandra X-ray Observatory, as well as the international Atacama Large Millimeter/submillimeter Array (ALMA), astronomers – and the public – can explore SN 1987A like never before.

Hubble has repeatedly observed SN 1987A since 1990, accumulating hundreds of images, and Chandra began observing SN 1987A shortly after its deployment in 1999. ALMA, a powerful array of 66 antennas, has been gathering high-resolution millimeter and submillimeter data on SN 1987A since its inception.

“The 30 years’ worth of observations of SN 1987A are important because they provide insight into the last stages of stellar evolution,” said Robert Kirshner of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., and the Gordon and Betty Moore Foundation in Palo Alto, Calif.

The latest data from these powerful telescopes indicate that SN 1987A has passed an important threshold. The supernova shock wave is moving beyond the dense ring of gas produced late in the life of the pre-supernova star when a fast outflow or wind from the star collided with a slower wind generated in an earlier red giant phase of the star’s evolution. What lies beyond the ring is poorly known at present, and depends on the details of the evolution of the star when it was a red giant. 

“The details of this transition will give astronomers a better understanding of the life of the doomed star, and how it ended,” said Kari Frank of Penn State University who led the latest Chandra study of SN 1987A.

Supernovas such as SN 1987A can stir up the surrounding gas and trigger the formation of new stars and planets. The gas from which these stars and planets form will be enriched with elements such as carbon, nitrogen, oxygen, and iron, which are the basic components of all known life. These elements are forged inside the pre-supernova star and during the supernova explosion itself, and then dispersed into their host galaxy by expanding supernova remnants. Continued studies of SN 1987A should give unique insight into the early stages of this dispersal. 

"A supernova remnant cools quickly, so within a few years the heavy elements formed in the star can form molecules and condense into dust, turning the remnant into a veritable dust factory,” said Remy Indebetouw of the National Radio Astronomy Observatory in Charlottesville, Va. "ALMA is now able to see this newly formed dust directly, and ongoing studies will help us understand how it forms and how supernovas seed interstellar space with the raw material for new planetary systems."

Some highlights from studies involving these telescopes include:

  • Hubble studies have revealed that the dense ring of gas around the supernova is glowing in optical light, and has a diameter of about a light-year. The ring was there at least 20,000 years before the star exploded. A flash of ultraviolet light from the explosion energized the gas in the ring, making it glow for decades.
  • The central structure visible inside the ring in the Hubble image has now grown to roughly half a light-year across. Most noticeable are two blobs of debris in the center of the supernova remnant racing away from each other at roughly 20 million miles an hour.
  • From 1999 until 2013, Chandra data showed an expanding ring of X-ray emission that had been steadily getting brighter. The blast wave from the original explosion has been bursting through and heating the ring of gas surrounding the supernova, producing X-ray emission.
  • In the past few years, the ring has stopped getting brighter in X-rays. From about February 2013 until the last Chandra observation analyzed in September 2015 the total amount of low-energy X-rays has remained constant. Also, the bottom left part of the ring has started to fade. These changes provide evidence that the explosion’s blast wave has moved beyond the ring into a region with less dense gas. This represents the end of an era for SN 1987A.
  • Beginning in 2012, astronomers used ALMA to observe the glowing remains of the supernova, studying how the remnant is actually forging vast amounts of new dust from the new elements created in the progenitor star. A portion of this dust will make its way into interstellar space and may become the building blocks of future stars and planets in another system. These observations also suggest that dust in the early universe likely formed from similar supernova explosions.
  • Astronomers also are still looking for evidence of a black hole or a neutron star left behind by the blast. They observed a flash of neutrinos from the star just as it erupted. This detection makes astronomers quite certain a compact object formed as the center of the star collapsed – either a neutron star or a black hole – but no telescope has uncovered any evidence for one yet.

Additional images, illustrations, and animations are found here: http://hubblesite.org/news_release/news/2017-08.

These latest visuals were made possible by combining several sources of information including simulations by Salvatore Orlando and collaborators that appear in this paper: https://arxiv.org/abs/1508.02275. The Chandra study by Frank et al. can be found online at http://lanl.arxiv.org/abs/1608.02160. Recent ALMA results on SN 87A are available at https://arxiv.org/abs/1312.4086.

The Chandra program is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

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

ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSC and ASIAA (Taiwan), and KASI (Republic of South Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ

 
nrao17cb14b
Astronomers combined observations from three different observatories to produce this colorful, multiwavelength image of the intricate remains of Supernova 1987A.

The red color shows newly formed dust in the center of the supernova remnant, taken at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.

The green and blue hues reveal where the expanding shock wave from the exploded star is colliding with a ring of material around the supernova. The green represents the glow of visible light, captured by NASA's Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA's Chandra X-ray Observatory.

The ring was initially made to glow by the flash of light from the original explosion. Over subsequent years the ring material has brightened considerably as the explosion's shock wave slams into it.

Supernova 1987A resides 163,000 light-years away in the Large Magellanic Cloud, where a firestorm of star birth is taking place.

The ALMA, Hubble, and Chandra images at the bottom of the graphic were used to make up the multiwavelength view.

Image Credit: NASA, ESA, and A. Angelich (NRAO); 
Hubble Credit: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation); 
Chandra Credit: NASA/CXC/Penn State/K. Frank et al.; 
ALMA Credit: ALMA (ESO/NAOJ/NRAO) and R. Indebetouw (NRAO/AUI/NSF)


This scientific visualization illustrates the evolution of Supernova 1987A from the initial swelling of the host star and supernova explosion to the expanding shock wave and the formation of molecules detected by ALMA in the remnant. Credit. A. Angelich (NRAO/AUI/NSF)
Astronomer Remy Indebetouw talks about the star that exploded in 1987, and how the world's telescopes have been watching the explosion ever since.  Additional animation and video credits: A. Angelich and B. Saxton, NRAO/AUI/NSF; R. Indebetouw et al., A. Angelich (NRAO/AUI/NSF); NASA/STScI/CfA/R. Kirshner; NASA/CXC/SAO/PSU/D. Burrows et al.; ESO; NASA/CXC/D.Berry/MIT/T.Delaney et al.; NASA/Goddard Space Flight Center Conceptual Image Lab; ESO/C. Malin/B. Tafreshi/José Francisco Salgado. Music: Geodesium.nrao17cb14c
Astronomers combined observations from three different observatories to produce this colorful, multiwavelength image of the intricate remains of Supernova 1987A.

The red color shows newly formed dust in the center of the supernova remnant, taken at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile.

The green and blue hues reveal where the expanding shock wave from the exploded star is colliding with a ring of material around the supernova. The green represents the glow of visible light, captured by NASA's Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA's Chandra X-ray Observatory.

The ring was initially made to glow by the flash of light from the original explosion. Over subsequent years the ring material has brightened considerably as the explosion's shock wave slams into it.

Supernova 1987A resides 163,000 light-years away in the Large Magellanic Cloud, where a firestorm of star birth is taking place.

Image Credit: NASA, ESA, and A. Angelich (NRAO); 
Hubble Credit: NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation); 
Chandra Credit: NASA/CXC/Penn State/K. Frank et al.; 
ALMA Credit: ALMA (ESO/NAOJ/NRAO) and R. Indebetouw (NRAO/AUI/NSF)
nrao17cb14d
About this image
This is an image of the intricate remains of Supernova 1987A taken in submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. The red color shows newly formed dust in the center of the supernova remnant.

Image Credit: NASA, ESA, and A. Angelich (NRAO); 
ALMA Credit: ALMA (ESO/NAOJ/NRAO) and R. Indebetouw (NRAO/AUI/NSF)

Quelle: NRAO


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Sonntag, 26. Februar 2017 - 07:30 Uhr

Astronomie - Neue Details zu Meteorit von Tscheljabinsk 2013

26.02.2017

Krimi um Meteoriten-Explosion über Russland 

Labor Universität Hannover, Rebecca Querfeld bei d…
Foto: /Rebecca QuerfeldLabor Universität Hannover, Rebecca Querfeld bei der Analyse eines Meteoriten
 

2013 explodierte über Russland ein Meteorit. Seine radioaktiven Überbleibsel werfen jetzt ein Schlaglicht auf eine lange vertuschte Atomkatastrophe.

 

Sie fallen unbemerkt in den Ozean, stürzen über der Sahara ab oder ins Eis der Antarktis. Manch einer hinterlässt sogar Spuren. Im Februar 2013 explodierte ein Meteorit über der russischen Stadt Tscheljabinsk. Er setzte dabei 30-mal so viel Energie frei wie die Atombombe von Hiroshima. Die Druckwelle der Explosion ließ Fensterscheiben in weitem Umkreis zerbersten, die Glassplitter verletzten an die 2000 Menschen. Zahlreiche Forscher und Sammler machten sich damals auf den Weg, um Brocken aufzulesen und sie im Internet zu verkaufen.

Jetzt konnte ein deutsch-österreichisches Forscherteam nachweisen, dass Bruchstücke des Meteoriten radioaktiv kontaminiert sind – keine natürliche Verunreinigung, sondern von Menschen verursacht, berichtet Georg Steinhauser. Er ist Physiker am Institut für Radioökologie und Strahlenschutz der Universität Hannover.

 
 

Bereits in Vorstudien fand man heraus, dass sich in den Bruchstücken des Meteoriten "Cäsium-137" befindet, es entsteht durch Kernspaltungsprozesse. Woher und wie es auf die Meteoriten-Teile kam, wusste aber niemand. War es radioaktiver Fallout von den atmosphärischen Kernwaffentests oder gar ein Überbleibsel des Tschernobyl-Unfalls? Steinhauser hatte einen anderen Verdacht.

Verschwiegener Unfall

1957 ereignete sich nahe der russischen Stadt Kyschtym eine folgenschwere Katastrophe, die lange geheimgehalten wurde. Erst nach dem Fall der Sowjetunion kam ans Licht, was damals passiert war: In der Nuklearanlage "Majak" reagierten zwei chemische Stoffe in den Lagertanks und explodierten. Eine kochende Säure-Fontäne schoss heraus. Hochradioaktiver Nebel legte sich über die Wälder, Seen und Dörfer der Umgebung. "Insgesamt wurde sogar mehr Radioaktivität freigesetzt als in Fukushima", berichtet Strahlen-Experte Steinhauser.

RUSSIA METEORITE

Foto: APA/EPA/YURI KOCHETKOV

Wie aber konnten die Wissenschaftler nun beweisen, dass die radioaktive Verstrahlung des Tscheljabinsk-Meteoriten von einem Nuklear-Unfall stammt, der vor 60 Jahren geschah? Ähnlich den Fernseh-Kollegen aus Serien wie "CSI" oder "Bones", mussten die Forscher aus Hannover forensische Methoden anwenden. Im Labor ätzten die Physiker um Rebecca Querfeld zunächst die Oberfläche des Meteoriten ab – die Gesteinsproben stellte ihnen das Naturhistorischen Museum Wien zu Verfügung. Sie lösten alle Verunreinigungen heraus, um sie zu untersuchen. Die Analyse zeigte überdurchschnittlich hohe Mengen an "Strontium-90", für Menschen aber ein unbedenklicher Wert.

Der Beweis war also gefunden, denn der radioaktive Stoff ist, laut Steinhauser, ein klassischer Indikator für den Unfall in der Nuklearanlage "Majak". Dort erzeugten die Sowjets damals Plutonium für das sowjetische Atomwaffenprogramm. "Cäsium-137" und "Strontium-90" blieben dabei als Abfallprodukte übrig. Während sie Cäsium für medizinische Präparate und technische Zwecke brauchten, fanden sie für Strontium keine Verwendung.

"Es ist ein besonders langlebiger, radioaktiver Stoff und wie sich zeigte noch immer im Boden, auch nach Jahrzehnten", sagt der erstaunte Experte. Es sollte es nicht die einzige Überraschung bleiben.

Magnetische Erde

Als die Wissenschaftler weitere Proben von der Meteoriten-Fundstelle untersuchten, stellten sie fest, dass es sich nicht um gewöhnliche Erde handelt: "Sie war komplett ferromagnetisch. Ich habe mit einem Spatel darin herumgestochert und es wirkte so, als würde er die Teilchen bewegen." Die Conclusio der Forscher: der Meteorit ist auf einer Industriehalde niedergegangen, die obendrein radioaktiv kontaminiert war. Die Ergebnisse ihrer Studie werden demnächst im Fachjournal Meteoritics & Planetary Science veröffentlicht.

Was dort ebenfalls nachzulesen ist: Die Physiker fanden in der Erde des Fundortes ein Mineral, das auf unserem Planeten besonders selten ist: Troilit – "das kann wiederum nur vom Meteoriten stammen", erklärt Georg Steinhauser. Das Geschoß aus dem All hat seinen Fundort also selbst "markiert" – und konnte überführt werden.

meteor_online.jpg

Quelle: Kurier,at

 


805 Views

Samstag, 25. Februar 2017 - 19:15 Uhr

Astronomie - Subaru Telescope sieht Saturns Ringe in Mittleren-Infrarot

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A team of researchers has succeeded in measuring the brightnesses and temperatures of Saturn's rings using the mid-infrared images taken by the Subaru Telescope in 2008. The images are the highest resolution ground-based views ever made. They reveal that, at that time, the Cassini Division and the C ring were brighter than the other rings in the mid-infrared light and that the brightness contrast appeared to be the inverse of that seen in the visible light (Figure 1). The data give important insights into the nature of Saturn's rings.

 

Figure 1

Figure 1: A three-color composite of the mid-infrared images of Saturn on January 23, 2008 captured with COMICS on the Subaru Telescope. The Cassini Division and the C ring appear bright. Color differences reflect the temperatures; the warmer part is blue, the cooler part is red. (Credit: NAOJ)

 

The beautiful appearance of Saturn and its rings has always fascinated people. The rings consist of countless numbers of ice particles orbiting above Saturn's equator. However, their detailed origin and nature remain unknown. Spacecraft- and ground-based telescopes have tackled that mystery with many observations at various wavelengths and methods. The international Cassini mission led by NASA has been observing Saturn and its rings for more than 10 years, and has released a huge number of beautiful images. 

 

Subaru Views Saturn

The Subaru Telescope also has observed Saturn several times over the years. Dr. Hideaki Fujiwara, Subaru Public Information Officer/Scientist, analyzed data taken in January 2008 using the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the telescope to produce a beautiful image of Saturn for public information purposes. During the analysis, he noticed that the appearance of Saturn's rings in the mid-infrared part of the spectrum was totally different from what is seen in the visible light

Saturn's main rings consist of the C, B, and A rings, each with different populations of particles. The Cassini Division separates the B and A rings. The 2008 image shows that the Cassini Division and the C ring are brighter in the mid-infrared wavelengths than the B and A rings appear to be (Figure 1). This brightness contrast is the inverse of how they appear in the visible light, where the B and A rings are always brighter than the Cassini Division and the C ring (Figure 2).

 

Figure 2

Figure 2: Comparison of the images of Saturn's rings in the 2008 view in the mid-infrared (left) and the visible light (right). The visible light image was taken on March 16, 2008 with the 105-cm Murikabushi telescope at Ishigakijima Astronomical Observatory. The radial brightness contrast of Saturn's rings is the inverse between the two wavelength ranges. (Credit: NAOJ)

 

"Thermal emission" from ring particles is observed in the mid-infrared, where warmer particles are brighter. The team measured the temperatures of the rings from the images, which revealed that the Cassini Division and the C ring are warmer than the B and A rings. The team concluded that this was because the particles in the Cassini Division and C ring are more easily heated by solar light due to their sparser populations and darker surfaces.

On the other hand, in the visible light, observers see sunlight being reflected by the ring particles. Therefore, the B and A rings, with their dense populations of particles, always seem bright in the visible wavelengths, while the Cassini Division and the C ring appear faint. The difference in the emission process explains the inverse brightnesses of Saturn's rings between the mid-infrared and the visible-light views.

 

Changing Angles Change the Brightnesses

It turns out that the Cassini Division and the C ring are not always brighter than the B and A rings, even in the mid-infrared. The team investigated images of Saturn's rings taken in April 2005 with COMICS, and found that the Cassini Division and the C ring were fainter than the B and A rings at that time, which is the same contrast to what was seen in the visible light (Figure 3).

 

Figure 3

Figure 3: Comparison of the mid-infrared images of Saturn's rings on April 30, 2005 (top) and January 23, 2008 (bottom). Although both of the images were taken in the mid-infrared, the radial contrast of Saturn's rings is the inverse of each other. (Credit: NAOJ)

 

The team concluded that the "inversion" of the brightness of Saturn's rings between 2005 and 2008 was caused by the seasonal change in the ring opening angle to the Sun and Earth. Since the rotation axis of Saturn inclines compared to its orbital plane around the Sun, the ring opening angle to the Sun changes over a 15-year cycle. This makes a seasonal variation in the solar heating of the ring particles. The change in the opening angle viewed from the Earth affects the apparent filling factor of the particles in the rings. These two variations – the temperature and the observed filling factor of the particles – led to the change in the mid-infrared appearance of Saturn's rings.

The data taken with the Subaru Telescope revealed that the Cassini Division and the C ring are sometimes bright in the mid-infrared though they are always faint in visible light. "I am so happy that the public information activities of the Subaru Telescope, of which I am in charge, led to this scientific finding," said Dr. Fujiwara. "We are going to observe Saturn again in May 2017 and hope to investigate the nature of Saturn's rings further by taking advantages of observations with space missions and ground-based telescopes."

Quelle: Subaru Telescope


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