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Sonntag, 18. September 2016 - 20:15 Uhr

Astronomie - Hungerndes Schwarzes Loch lässt hell leuchtende Galaxie wieder verblassen

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Dieses Bild vom MUSE-Instrument am Very Large Telescope der ESO zeigt die aktive Galaxie Markarian 1018, die ein supermassereiches Schwarzes Loch in ihrem Kern beherbergt. Die lichtschwachen Ringe aus Licht um die Galaxie sind das Ergebnis von Wechselwirkungen und Verschmelzung mit einer anderen Galaxie in jüngster Vergangenheit.

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Ein internationales Astronomenteam mit starker deutscher Beteiligung hat mit dem Very Large Telescope der ESO und dem Röntgensatelliten Chandra der NASA das Rätsel um die ungewöhnliche Veränderung im Verhalten eines supermassereichen Schwarzen Lochs im Zentrum einer weit entfernten Galaxie gelöst. Es scheint, als stünden dem Schwarzen Loch harte Zeiten bevor, da es nicht mehr mit ausreichend Materie gefüttert wird, um weiterhin seine Umgebung aufleuchten lassen zu können.

Im Zentrum vieler Galaxien findet sich ein supermassereiches Schwarzes Loch, das den Galaxienkern extrem hell leuchten lässt. Solche „Aktiven Galaxien“ werden dadurch zu den hellsten Objekten im Universum. Man geht davon aus, dass heiße Materie, die ins Schwarze Loch hineinfällt, die Ursache für das helle Leuchten ist. Dieser Prozess wird auch als Akkretion bezeichnet. Das dabei entstehende helle Licht kann bei verschiedenen Aktiven Galaxien sehr unterschiedlich sein, so dass Astronomen sie je nach Eigenschaft des Lichtes, das sie aussenden, in mehrere Typen unterteilen [1].

Manche Galaxien scheinen sich im Laufe von nur 10 Jahren dramatisch verändert zu haben; in astronomischen Größenordnungen ist das mit einem Wimpernschlag vergleichbar. Die Aktive Galaxie Markarian 1018, die in dieser Arbeit untersucht wurde, sticht jedoch besonders hervor, da sie ihren Typ innerhalb der letzten fünf Jahren bereits zum zweiten Mal geändert hat und inzwischen wieder dieselbe Klassifizierung innehat wie zu Beginn. Nur bei einer Handvoll Galaxien wurde solch ein kompletter Veränderungszyklus beobachtet, jedoch wurde keine davon bisher so genau untersucht.

Die Entdeckung der unbeständigen Natur von Markarian 1018 gelang zufällig im Rahmen des Close AGN Reference Survey (CARS), einem Kollaborationsprojekt zwischen der ESO und anderen Organisationen, das zum Ziel hat, Informationen über 40 nahe Galaxien mit Aktiven Kernen zu sammeln. Routine-Beobachtungen von Markarian 1018 mit dem Multi-Unit Spectroscopic Explorer (MUSE), der am Very Large Telescope der ESO installiert ist, brachten die überraschende Veränderung im emittierten Licht der Galaxie zutage.

Wir waren verblüfft, solch eine seltene und dramatische Veränderung in Markarian 1018 zu beobachten”, erzählt Rebecca McElroy, Erstautorin des Fachartikels zur Entdeckung und Doktorandin an der University of Sydney und am ARC Centre of Excellence for All Sky Astrophysics (CAASTRO).

Die zufällige Beobachtung der Galaxie so kurz nachdem sie anfing zu verblassen, war eine unvorhergesehene Möglichkeit etwas darüber zu erfahren, wie Galaxien ticken, erklärt Bernd Husemann, CARS-Projektleiter und Erstautor des zweiten Fachartikels in Zusammenhang mit dieser Entdeckung: „Wir sind froh, dass wir dieses Ereignis nur 3-4 Jahre nach Beginn der Helligkeitsabnahme entdeckt haben, sodass wir mit einer Überwachungskampagne beginnen konnten, um die physikalischen Details der Akkretionsprozesse Aktiver Galaxien zu untersuchen, die ansonsten nicht erforscht werden könnten.

Um aus dieser seltenen Gelegenheit das Beste herauszuholen, hatte es für das Forscher-Team fortan oberste Priorität, genau herauszufinden, welcher Prozess dafür sorgt, dass sich die Helligkeit von Markarian 1018 so plötzlich und stark wieder ändert. Dafür kommen eine Reihe astrophysikalischer Ereignisse in Frage, jedoch konnten sie ausschließen, dass das Schwarze Loch einen einzelnen Stern angezogen und verschluckt hat [2]. Außerdem bezweifelten sie auch die Möglichkeit der Verdunkelung durch Gas, das in die Sichtlinie getreten ist [3]. Der wahre Mechanismus, der für die erstaunliche Veränderung von Markarian 1018 verantwortlich ist, bleibt nach der ersten Beobachtungsrunde weiterhin ein Geheimnis.

Allerdings bekam das Team die Möglichkeit mit dem Hubble-Weltraumteleskop der NASA/ESA und dem Röntgensatelliten Chandra der NASA zusätzliche Daten zu sammeln. Mit den neuen Daten dieser Instrumente konnten sie das Rätsel lösen – das Schwarze Loch verblasste langsam, da ihm die Materie ausging und es demzufolge nichts mehr akkretieren konnte.

Es ist möglich, dass es langsam verhungert, da der Zufluss neuer Materie unterbrochen wurde“, meint Rebecca McElroy. „Eine reizvolle Möglichkeit wäre, dass der Grund dafür Wechselwirkungen mit einem zweiten supermassereichen Schwarzen Loch sind“. Solch ein Doppelsystem aus Schwarzen Löchern ist eine klare Option in Markarian 1018, da die Galaxie das Endprodukt einer Verschmelzung zweier großer Galaxien ist – von denen jede wahrscheinlich ein supermassereiches Schwarzes Loch im Zentrum beherbergt hatte.

Die Erforschung der Mechanismen, die in aktiven Galaxien wie Markarian 1018 am Werk sind und dafür sorgen, dass die Galaxie ihre Erscheinung ändert, gehen weiter. „Das Team musste sich beeilen, den Grund dafür zu finden, warum Markarian 1018 wieder verblasst“, merkt Bernd Husemann an. „Laufende Beobachtungskampagnen mit Teleskopen der ESO und anderen Einrichtungen werden es uns ermöglichen, die aufregende Welt verhungernder Schwarzer Löcher und sich verändernden aktiven Galaxien genauer zu erkunden.

Endnoten

[1] Die hellsten Aktiven Galaxien stellen die Quasare dar, in denen der helle Kern den Rest der Galaxie überscheint. Eine andere, weniger extremere Klasse sind die sogenannten Seyfert-Galaxien. Ursprünglich wurde eine Methode entwickelt, die auf der Helligkeit und dem Emissionsspektrum basierte – die grafische Darstellung der Stärke der emittierten Strahlung bei unterschiedlichen Wellenlängen – um nur zwischen zwei Typen von Seyfert-Galaxien zu unterscheiden, Typ 1 und Typ 2. Jedoch wurden in der Zwischenzeit auch zusätzliche Klassifizierungen eingeführt, wie Typ 1,9.

[2] Wenn ein Stern sich einem supermassereichen Schwarzen Loch zu sehr nähert, wird er durch die extremen gravitativen Gezeitenkräfte auseinandergerissen. Solch ein Ereignis führt zu einer schnellen Helligkeitszunahme im Zentrum, während die Helligkeit anschließend über einen Zeitraum von mehreren Jahren wieder langsam abnimmt.

[3] Verdunkelung durch Gas kann einen Einfluss auf die Klassifizierung einer Aktiven Galaxie haben, indem es das Licht zwischen Beobachter und dem hellen Kern der Galaxie blockiert, vergleichbar mit Nebel vor den Scheinwerfern eines Autos, und so das Licht verdunkelt, dass durchdringen kann. Dies beeinflusst auch das Spektrum der Galaxie, wodurch sich möglicherweise auch ihre Klassifizierung ändert.

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Die Himmelsregion um die Aktive Galaxie Markarian 1018

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Quelle: ESO

 


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Sonntag, 18. September 2016 - 14:00 Uhr

Astronomie - Herkunft der Kleinplaneten Ringe enthüllt

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Visualization of Chariklo and its rings ( left; ESO/L. Calçada/M. Kornmesser/Nick Risinger). Visualization of the rings as seen from Chariklo's surface (right ESO).

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A team of researchers has clarified the origin of the rings recently discovered around two minor planets known as centaurs, and their results suggest the existence of rings around other centaurs. These findings were published on August 29 in Astrophysical Journal Letters, and introduced in AAS Nova, a website for research highlights from the journals of the American Astronomical Society.

The lead author of the paper is HYODO Ryuki (Kobe University Department of Planetology, Graduate School of Science), and co-authors are Professor Sébastien Charnoz (Institute de Physique du Globe/Université Paris Diderot), Project Associate Professor GENDA Hidenori (Earth-Life Science Institute, Tokyo Institute of Technology), and Professor OHTSUKI Keiji (Kobe University Department of Planetology, Graduate School of Science).

Centaurs are minor planets that orbit between Jupiter and Neptune, their current or past orbits crossing those of the giant planets. It is estimated that there are around 44,000 centaurs with diameters larger than one kilometer.

Until recently it was thought that the four giants such as Saturn and Jupiter were the only ringed celestial bodies within our solar system. However, in 2014 observations of stellar occultation (an event that occurs when light from a star is blocked from the observer by a celestial body) by multiple telescopes revealed that rings exist around the centaur Chariklo. Soon after this, scientists discovered that rings likely exist around another centaur, Chiron, but the origin of the rings around these minor planets remained a mystery.

The team began by estimating the probability that these centaurs passed close enough to the giant planets to be destroyed by their tidal pull. Their results showed that approximately 10% of centaurs would experience that level of close encounter. Next, they used computer simulations to investigate the disruption caused by tidal pull when the centaurs passed close by the giant planets. The outcome of such encounters was found to vary depending on parameters such as the initial spin of the passing centaur, the size of its core, and the distance of its closest approach to a giant planet. They found that if the passing centaur is differentiated and has a silicate core covered by an icy mantle, fragments of the partially-destroyed centaur will often spread out around the largest remnant body in a disc shape, from which rings are expected to form.

The results of their simulations suggest that the existence of rings around centaurs would be much more common than previously thought. It is highly likely that other centaurs with rings and/or small moons exist, awaiting discovery by future observations.

Notes

1. Centaur: small celestial bodies that orbit between Jupiter and Neptune. Their current or past orbits repeatedly cross those of the giant planets, and sometimes pass very close by the giant planets themselves.

2. Chariklo: a centaur with a radius of approximately 250 kilometres. In 2014 it was clarified by stellar occultations that this centaur has rings.

3. Chiron: a centaur with a radius of approximately 220 kilometres. Like Chariklo, it is thought to possess rings based on data from multiple observations.

Quelle: SD


985 Views

Sonntag, 18. September 2016 - 10:00 Uhr

Mars-Chroniken - Seismische Risse könnten lebenserhaltenden Wasserstoff auf dem Mars produzieren.

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Seismic rifts may have produced life-sustaining hydrogen on Mars.
‘Marsquakes’ Could Facilitate the Evolution of Life on Mars

Earthquakes are usually terrifying natural disasters that endanger thousands of lives — but on Mars, they could help give life to alien species.

new study published in the journal Astrobiology finds that earthquakes produce rocks that are subsequently richer in trapped hydrogen. The results, taken a step further and applied to extraterrestrial worlds, suggest “marsquakes” could also encourage the type of hydrogen-rich geology necessary to support life.

You’re probably familiar with the idea of carbon as the building block for organic life. But in order for carbon to become anything more special than just carbon, it needs to bond with other elements, including hydrogen. We know that rocks formed by quake-induced grinding against other rocks end up supercharged with hydrogen, and that Mars has enough seismic activity to produce them. If there’s enough hydrogen around and conditions are right, Martian life could theoretically evolve.

Of course, the state of Mars’ hydrogen supply can’t be confirmed just yet. One of our most promising options for gathering more data about the planet’s surface is NASA’s Mars InSight mission, which has been delayed two years. Originally scheduled to kick off earlier this year and now slated for May 2018, InSight (short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) remains NASA’s big-budget plan to physically place a lander on Mars to collect data illustrative of the planet’s interior. There have been a string of projects geared toward investigating Mars’s surface — InSight will be the first that attempts to literally go deeper, focusing on the core, mantle, and crust.

“Mars is not very seismically active, but our work shows that Marsquakes could produce enough hydrogen to support small populations of microorganisms, at least for short periods of time,” Yale geologist and first author Sean McMahon told YaleNews. “This is just one part of the emerging picture of the habitability of the Martian subsurface, where other sources of energy for life may also be available. The best way to find evidence of life on Mars may be to examine rocks and minerals that formed deep underground around faults and fractures, which were later brought to the surface by erosion.”

Quelle: INVERSE


987 Views

Sonntag, 18. September 2016 - 09:00 Uhr

Astronomie - REMEMBER PLUTO ? Nun, er könnte wieder ein PLANET werden

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Pluto, the small, icy rock floating 3.6 billion miles from the sun, hasn’t been a full-fledged planet since 2006. The International Astronomical Union, a group of professional astronomers, ruled that, by their standards, Pluto doesn’t make the cut. But not everyone agrees with that ruling. Some hold out hope that Pluto may eventually rejoin Earth and the eight other planets.

One of those astronomers is Alan Stern, a planetary scientist and principal investigator of the New Horizons mission to Pluto. Last year, their small space probe flew by Pluto and gathered data previously unknown to man.

“It doesn’t take an expert to take a look at Pluto, which New Horizons revealed in all of its glory, and tell just by looking that it’s obviously a planet,” Stern says. “And somehow, all those astronomers who work on stars and galaxies just got it wrong ten years ago.”

Stern is not alone – he has millions of people on his side. In fact, one quick Google search and you can find scores of articles sparking a public debate on Pluto’s classification. Stern says that according to him and other planetary experts, there is no question to Pluto’s legitimacy. It is just a matter of the press catching up to this fact.

But with this level of certainty, what did the New Horizons mission provide us in terms of Pluto and the future of space travel?

“This is the first mission in a generation to go exploring a new planet and what we found was completely unexpected,” Stern says. “A small planet, on the frigid outer border of our solar system that’s just as complex as the Earth or Mars, it’s still geologically alive today with blue skies, five moons, volcanoes, vast mountain ranges and glaciers.

“The New Horizons mission was a breakthrough in many ways. … It’s opened up our ability to do more exploration for less money and less time, and the results, scientifically, just keep pouring in.”

Quelle: TEXAS STANDARD


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Samstag, 17. September 2016 - 21:30 Uhr

UFO-Forschung - The Skylab-3 UFO-Foto

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Some recent e-mail exchanges had me wondering about the Skylab 3 incident that was promoted on Paul Kimball’s top ten UFO events film. Those writing about the incident give us a one-sided interpretation of what was reported. Discussions with James Oberg revealed that there are some things that were not considered.

The incident

On September 20, 1973, at approximately 1645 GMT, the Skylab 3 astronaut crew was in the wardroom of the station and noticed a bright red “satellite” visible through the window. According to the crew’s initial comments to CAPCOM, at 2106 GMT, they had seen a “huge” satellite a few orbits before. Jack Lousma stated, “...it was reflecting in red light, and oscillating at, oh, considering its period of brightest to dimmest, about ten seconds. It led us into sunset...” 1 Owen Garriot took four photographs of the object and that was the end of the story until the debriefing a few weeks later.

During the debriefing, the story changed. The crew now stated that the object went into shadow after Skylab by five seconds or so indicating the object was trailing the space station.2 This is the story that has been repeated by the UFOlogists but is it accurate?

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The photographs

There were four photographs of the UFO, which were taken by Owen Garriot. He used a Nikon F camera specifically designed for use on the station.3 The camera had two lenses. One was a 55mm and the other was a 300mm. The camera was a manual type where the as- tronaut would adjust the aperture settings and exposure time based on the light meter visible in the viewfinder. Exposure time could be as fast as 1/1000th of a second and as slow as 1 second. There was also a “T” setting, which is the same thing as the “bulb” setting found on most cameras. The camera also had a motor drive to advance the film but it could also be advanced manually.

The exact exposure time and lens used is difficult to determine since it was apparently not recorded on the data sheet for the photographs. Brad Sparks and Bruce Maccabee assume the photographs were tak- en using a 300mm telephoto lens and a 1/500th second shutter speed because that was the shutter speed setting for photographs preced- ing the event. 4 However, as a photographer, I disagree with this con- clusion.

Any experienced photographer (the astronauts were not amateurs and were trained in photography), would recognize photographing an object in darkness would mean that a longer exposure time would be required. Under these conditions, the light meter in the camera would be unable to compute an accurate exposure time based on a point source of light. This means the astronaut would have relied upon their experience/knowledge to select the shutter speed. If I were photographing such an object with a film camera, I would have tak- en several images using a range of exposures with the aperture wide open. This would especially be true if I were using a telephoto lens.

Since we don’t know the actual exposure time or lens, we have to as- sume that Garriot would have attempted to use a specific exposure time and then bracketed that exposure time. There seems to be evidence of this since one of the photographs (2140) appears to be underexposed, where the light is barely recorded on the film. The other images show varying brightness for the object.5 The one image that is the prize for UFO proponents is the last image

(2141). It shows an interestingly shaped object that looks like a squiggly line (see next page).

Image 2141

In my opinion, this image is the result of photographing a point source with a long exposure time. The action of pressing the shutter and trying to keep the camera still during the exposure resulted in the resultant “squiggle”. Maccabee disagrees because he feels that the effects of weightlessness and the use of a short exposure time would have prevented such an effect. One can not conclude that Garriot used the same exposure time as the previous daylight image without better evidence. Such a conclusion as- sumes that Garriot was nothing more than an amateur shutterbug that did not think about what he was photographing. If he did try and compensate for photographing a point source in darkness, he would have shot the photographs using much longer shutter times than 1/500th of a second. As a result, the potential for induced vibration by the operator pressing the shutter or not holding

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the camera still would be possible.

While discussing this with James Oberg, he presented me with an image taken from the space station showing a similar “squiggle” photograph of a point source.6

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In an effort to duplicate the results of the camera with a bright point source, I used my Nikon D5000, with a 180mm fixed focal length lens, to take photographs of the planet Mars (about magnitude -1.8). In an attempt to duplicate the equipment used, I stopped the lens down to 5.6 (the normal f-stop for a 300mm telephoto lens) and set the ISO to 200. I hand-held the camera but attempted to hold it steady by propping my elbows on a fixed surface. Despite this extra effort, I still induced motion on several photographs. The results can be seen on the page. The top image shows Mars under vary exposure settings from 1/250th to 1/8th of a second exposure. The planet exhibited vibration from pressing the shutter button starting at 1/30th of a second. The motion was easily noticeable at 1/15th and 1/8th of a second. Interestingly, the image is a point source in the faster exposures but faint, requiring the arrows, just like the Garriot photos.

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On the next page are cropped sections (no zoom) of three 1/8th of a second exposures of the planet Jupiter (taken in twilight) and Mars. The resultant “squiggles” are indicative of how camera motion can produce a variety of shapes/lines when using long expo- sure times. I tried to keep my arms steady on all of these shots but I have never been very successful in taking hand-held images at 1/8th of a second. I don’t think it would matter if it were a weightless environment since the action of a pressing the shutter button and the resultant motion of the mirror during the exposure would still induce some blur.

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James Oberg’s statements

On Robert Sheaffer’s web site, he has commentary by James Oberg regarding the Skylab 3 UFO. After describing the case, Oberg states:

Within the past two years I’ve met face-to-face with Garriott and Lousma, for other purposes, but discussed the sighting with them. I’ve also discussed it by phone with Bean [who lives in Houston, but I’m not a frequent visitor at his home studio], but read his book’s account of the sighting. I first met these men in the 1970s when I went to work at the Johnson Space Center, and have stayed in touch over the years. To my knowledge, neither Maccabee nor Sparks has ever contacted them directly.

The interpretation of the object’s dimming at sunset at a different time than Skylab dimmed, as an indicator of the object’s actual large range, is flawed on two counts. First, the interpretation requires assumptions of the object’s altitude and other orbital characteristics that are merely convenient guesses and cannot otherwise be corroborated. Second, the assumption that there is no other possible explana- tion for the difference in dimming time than large physical separation showing up as different sunset times, is incomplete.

There is another common illumination phenomenon that allows objects near a space vehicle to move into or out of sunlight, that is to- tally independent of orbital sunrise/sunset. That is shadowing by the observing spacecraft, an optical phenomenon seen on some space shuttle TV downlinks of water dumps and views of other small drifting nearby objects shed by the shuttle. This alternative explanation was not, as best I recall, discussed or eliminated by Maccabee and Sparks.

The prosaic explanation of the dot as a nearby Skylab-shed piece of debris is supported by three arguments:

1. Similar Skylab-shed small debris was observed on all three Skylab missions, mostly as dots transiting the solar disk during observations using the station’s solar telescope.

2. The wardroom window through which this particular object was observed was on the down-sun side of the station, and during the sunset phase of each orbit the station was casting an invisible umbra extending hundreds of meters down-sun. Because the station had already crossed the Earth’s terminator, the surface below was in darkness and hence not reflecting sunlight back up into this shadow zone [as happens during most of every daylight pass] so anything in that zone would not be illuminated and would not be visible. Something moving near the station -- originally away from it but quickly into a possible parallel or closing path -- could move from sunlight into this zone and appear to vanish.

3. The long duration of the observation, measured in minutes, eliminates the possibility of it being an independent satellite in any differ- ent orbit. This is because satellites in crossing orbits have such high relative velocity that the angular velocity is too large even for most eyeball detection, much less minutes of patient watching. Note that here I am conceding Maccabee’s argument from the Gemini-11 case that the ‘UFO’ could not have been the Soviet ‘Proton’ satellite because it remained in visual and camera range too long [I now favor Sparks’s view that the crew observed a bundle of surplus spacewalk tools jettisoned manually a few hours earlier]. I also can report an independent search of known large satellites in orbit at that time [including classified vehicles whose orbital data was released decades later] and agree that no other independent satellite affords an explanation of the sighting. But Skylab-shed debris was never observed from the ground [too small], and not tracked.

4. Less powerful is another argument, that an object of the actual physical size postulated by Maccabee and Sparks would have been a bizarre naked-eye object of discernable angular size in the skies of Africa as it passed directly across that continent, yet to my knowledge no UFO reports remotely related in appearance, timing, or direction, have ever been found.

Considering the known visual stimuli engendered by the Skylab vehicle, the particular illumination conditions of the ‘sunset shadow’, and the unanimous testimony of all three witnesses as verified by three of the four photographs taken, I see no compelling case to believe the fourth image is anything but a camera or processing artifact.7

I believe that Oberg was mistaken about Maccabee/Sparks not contacting the astronauts because, in Maccabee’s article, he states 

that Sparks did speak to Garriot about the incident but the best he could get from him was the fact that Garriot counted a certain way to get his time estimate correct.

The rest of Oberg’s arguments need to be considered. Probably the most interesting point he raised was that it would be impossible for the object to be trailing Skylab because the wardroom window did not normally point towards the sun. Considering the dark-

ness of the background, it seems he is correct but I wanted to make sure.

The orientation of Skylab

The Skylab station had to generate electricity using its solar panels. This required the space station to position itself so it was facing the sun:

Two precise control systems permitted the astronauts to orient the workshop to collect experimental data and to position Skylab so that its solar arrays faced the Sun.8

This image on the demonstrates how the station would orient itself during its orbit so it could photograph the Earth’s surface.9

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The Wardroom window’s location

One can see the various viewing window locations in the image on the next page.10 The wardroom window (#8) was on the op- posite side of the ATM. Based on what we know about the normal orientation of the craft as it passed into Earth’s shadow, it appears that Oberg is correct. The astronauts were viewing in the eastward direction and not the westward as proposed by Sparks and Maccabee. This introduces many other possibilities not considered by those, who consider this evidence of some exotic craft.

This also indicates that the statements made by the astronauts in their debriefing were incorrect as to the location of the satellite relative to the station. One has to consider the fact that the debriefing occurred roughly two weeks after the event and the potential exists they “misremembered” the details. It now appears that the statements made by the astronauts to CAPCOM just hours after the event were the most accurate.

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Which shadow did the object disappear into?

The disappearance of the object into shadow has always been interpreted as being the shadow of the earth. However, with the object being ahead of Skylab, another possibility exists. The space station would be casting its own shadow and it could have been what caused the object to disappear. If that was the case, the object could have been smaller and closer to the station than estimated.

A mysterious satellite?

Why wasn’t this object tracked if it was something large in orbit? The Space Detection and Tracking System (SPADATS) mon- itored everything in orbit during the 1970s. If there was some object of significant size near the Skylab space station, they would have recorded it. The same could be said for ground based observers. In this instance, the Skylab space station would have been visible to ground based observers in Africa. Nobody reported seeing a bright object moving across the sky with Skylab on that date. Since there seems to be no record of any mysterious satellite moving with the station, it indicates the object was not that large.

Space debris?

James Oberg has suggested that what was seen was space debris from the station itself. The fact that the object appears to have been pacing Skylab in a similar orbit supports that possibility. The source may have been a bit of reddish foil found on the parasol deployed by the Skylab 2 on May 26th or the second sun shade deployed by the Skylab 3 crew on August 7th. Something like that reflecting sunlight might appear red. Since the astronauts mentioned that the object was changing its location relative to the sta- tion, then the object would no longer be in position to be seen again on the following orbit.

Conclusion

The promotion of the event by UFOlogists downplayed, or ignored, the possibility the shape was due to the photographer press- ing down on the shutter mechanism while using a relatively long exposure time. They also seem to have “cherry picked” the testimony, which supports an exotic explanation instead of the testimony that supports a more prosaic answer.

While no positive identification can be made with the information available, there seems to be enough information to suggest what was seen was a piece of debris floating in a similar orbit. This is more likely than some form of exotic craft that was investigating the space station.

Quelle: SUNlite 4/2016

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Aus dem CENAP-Archiv:

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Quelle: CENAP-Archiv


935 Views

Samstag, 17. September 2016 - 20:00 Uhr

UFO-Forschung - Herausforderung: NARCAP UFO-Foto-Fall Montebello

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A NARCAP case challenge

On April 30th, Ted Roe, of the National Aviation Reporting Center on Anomalous Phenomena (NARCAP), posted a UFO (not UAP) challenge on Facebook. He wanted people to explain some photographs taken by an amateur photographer of a UAP appear- ing near an aircraft back in 2005.1

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Several members of Gilles Fernandez’ Facebook group “UFO Pragmatism” saw the challenge and discussed the event. We noted several anomalies that indicated the story was not as good as indicated in the NARCAP report and some mistakes were made.

The case

The report in question involves an amateur photographer, who was photographing the evening sky at the Montebello open space preserve, near Palo Alto, California. The date was July 3, 2005 and the time was 2031 PDT. Using his Canon digital SLR (A Rebel XT), the witness managed to record some images of an airplane that, according to him, was flying eastward towards Santa Cruz. The initial photograph was a wide angle image with the plane visible to the north of the observer. 2

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Seeing something odd, the witness then zoomed in and managed to record a bright dot that was traveling in the opposite direction of the aircraft. According to NARCAP, this was something truly anomalous that could not be explained.

NARCAP interviewed the witness and made all sorts of measurements from the photographs. They determined that the plane traveled north of the observer from an azimuth of 315 degrees to 030 degrees. 3 In addition to the wide angle image, the witness provided three images taken with a 135mm lens showing the aircraft and the UAP. These photographs were the centerpiece of their report.

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What is wrong with this picture?

When our group chose to examine the report, several explanations were proposed but something caught everyone’s eye that made us question the analysis. The photographs of the airplane do not appear to match the description of what the witness stated happened. Even more of an issue is that NARCAP never noticed these problems and seemed to have blindly accepted the story told by the witness.

NARCAP makes much of the 135mm photographs of the plane pointing out where the different parts of the aircraft are. They even note the speck of reflected sunlight on the front of the aircraft’s nose. However, they ignored how the sun was illuminating the aircraft when they accepted the witness testimony that the plane was flying East or Southeast and was north of the photographer’s location.

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At the time of the event, the sun was setting in the west. Had the plane being flying to the East or SouthEast, the plane’s tail section and part of the starboard side of the aircraft would have been illuminated by the sun. Instead, as one can see in photograph #24, the port side of the plane is illuminated by the setting sun. This means the plane would had to have been flying in a northerly direc- tion (NW, N, NE) and be to the west or southwest of the observer. This contradicts what the witness stated and the path proposed by NARCAP. We do not even know if this was the same aircraft shown in the wide angle image taken a few seconds prior to this.

Wondering if there was confusion, several of the group tried to contact NARCAP on their Facebook page hoping to get access to the RAW images or, at least, the EXIF data, which was missing from the report. NARCAP claims that there are copyright concerns and would not provide the images or the EXIF data!5 While I can see not providing the images, I don’t understand how the EXIF

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data could fall under the copyright protection. One would think that Dr. Richard Haines would have looked at the EXIF data and published it.

The reason we wanted to see the EXIF data was to see if the times for the photographs were in the same sequence as the published information. It seems that there appeared to be serious problems with what the witness described and what the photographs showed. This is indicative of a possible hoax.

Other problems with the report appeared after closer examination. The numbering of the images appears to be wrong. Photo- graph #2 is listed as frame 4 of 8 and photograph #4 is listed as 2 of 9!6 Photograph #3 has no “frame number” but examination by the group revealed that it appears to be the same image as photograph #4 shown in a different scale. I rescaled photograph #4 and over-layed it on #3 and got this result:

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This indicates that they are the same photograph. Another image in the report, which is listed as coming from figure 4 (photograph #3) verifies this because it shows the UAP in a different location.7 How could a scientific paper, that has undergone peer review, allow such an error to appear?

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This demonstrates that the UAP was moving away from the aircraft at the same rate and in the opposite direction the plane was moving. It seems possible, based on this information, that the displacement may have been more to do with the plane’s motion and not the UAP itself.

A lack of proper analysis?

Without the raw data (the original images), it is hard to compute the angular distances as well as test the conclusions of NARCAP. Since NARCAP chose not to calculate these values or present measurements so others could reproduce the work, we are stuck with using cropped images that are difficult to evaluate.

NARCAP states that at the time of photograph #1, the plane was at a 40 degree angle of elevation.8 We are also told that this pho- tograph was taken using a 28mm lens. A 28mm lens has a vertical field of view (FOV) of about 30 degrees.9 If the plane was at a 40 degree elevation, it would be impossible for the plane to be in the same FOV as the horizon, which means NARCP did not bother to check up on the value provided by the witness. In photograph #1, the plane is only about 1/3rd of the FOV above the horizon, which is about 10 degrees.

NARCAP also states that the plane was 8211 feet from the camera.10 They don’t show how they calculated this but it appears to be based solely on the estimates by the witness. In photograph #4, the plane’s size is about 4.3% of the full horizontal frame shown. A 135 mm lens has a horizontal FOV of 10 degrees.11 This means the plane was about 0.43 degrees across. While the plane is not being seen from a right angle, an approximate distance can still be calculated. A Boeing 757 is 179 feet long, which means the distance to the plane was approximately 24000 feet. This is much further away than 8211 feet.

Another value that should have been determined by NARCAP was how fast the UAP was moving relative to the aircraft. By using the plane’s length and physical size in the image, one can compute the approximate speeds of the object as it is separating from the plane.

The report states that the camera was using burst mode, which produces approximately one frame per second.12 This is not correct. According to the Canon Rebel XT manual (as well as other sources), the actual frame rate for the camera in “burst mode” is three frames per second!13 This means that each frame is approximately 1/3rd of a second apart. Since the Boeing 757 is 179 feet long, the distance traveled between photographs 2 and 3 would be:

0.8 * 179 feet/0.3 sec = 477 feet per second or roughly 325 mph.

We don’t know the plane speed but we can estimate it based on the plane’s apparent pitch angle. Looking at the image, it appears that the plane is in a climb. Below 10,000 feet, climbing speed for a 757 is about 250 knots indicated air speed.14 Indicated air speed is not the same as true air speed but this can be converted using an on line calculator. 15 For a 5000 foot altitude, the plane would be flying at 275 knots true air speed (about 316 mph).This means the UAP would have to be flying in the opposite direction at about 9 mph IF it were at the same distance as the aircraft. If it were closer to the camera, it would be traveling much slower. With such a slow speed, one can assume it is possible that the UAP was essentially stationary in between photographs and that the separation had more to do with the aircraft’s motion than the UAP moving in the opposite direction.

What we appeared to have discovered is that there was little effort by NARCAP to evaluate the evidence properly and multiple errors have been made. Is this really a reliable UFO/UAP case when the hard data was apparently ignored in favor of the anecdotal report?

The witness

In an effort to obtain the information our group desired, I sent a letter to the witness (one of the Facebook group had found a potential address) because there was no e-mail address. I encouraged the witness to contact me so we could ask him questions about the photographs. He never responded. I can only assume the person I mailed the letter to was not the witness, the witness moved, or the witness did not want to discuss the matter for their own personal reasons. It was hoped that he could resolve the problems with the supposed path of the aircraft and the imagery sequence since NARCAP was unwilling/unable to provide the information upon request.

It might be important to note that the witness was not just a stray photographer, who had no interest in UFOs/UAPs prior to taking these photographs. He specifically mentioned listening to “Coast-to-Coast AM” and being aware of the National UFO Reporting Center for a significant period of time prior to submitting these UFO photographs for examination:

...the only reason I even thought to photograph what I was seeing was hearing Mr. Davenport on Coast-to-Coast AM for years now.16

Is it possible that he was preconditioned to present a UFO report when he thought he saw something extraordinary? Is it possible that preconditioning might also tend to embellish details and get facts wrong?

Possible explanations

Several in our group thought the white object was the planet Venus. With Venus stationary and the plane in motion, the object would appear to go in the opposite direction of the plane. My only problem with the Venus explanation was that the planet Venus was not that bright and only about 24 degrees from the sun at the listed date and time of the photographs.

I originally thought the object might be a hot pixel and the plane’s motion made the object appear to go in the opposite direction. Without the full frames being available, this theory could not be tested but after examining all the images, this explanation seems unlikely.

A very possible candidate is that it was a small balloon. NARCAP states that the winds do not support a balloon hypothesis because

they were blowing to the east and the object moved to the west. The object’s direction of movement is based on what the witness told them and not what we see in the photographs. Since less than a second separated the three photographs, one would see very little motion associated with an object being blown by the wind unless it was within a few hundred feet of the camera. As stated previously, if the UAP was a balloon floating relatively stationary in the sky and was closer to the camera than the plane, the plane’s motion would probably create all of the displacement seen between the three photographs.

Without more data, it is difficult to come up with a firm conclusion. Based on what we can determine from the photographs, the witness’ story is suspect as is the analysis in the report. Failure to share the raw information from the images indicates that NARCAP was never interested in giving those answering the challenge a fair opportunity to do so.

NARCAP challenge = NARCAP failure?

In my opinion, this report appears to contain editing errors and was poorly researched. The lack of EXIF data being provided, get- ting the images wrong, and failing to do simple angular calculations indicates some pretty poor analysis. Either the report was sloppily written or the analysis was specifically written so the reader only saw information that supported the desired conclusion. Issuing a challenge to a report with so many flaws indicates that NARCAP did not conduct a thorough review of what was present- ed. If NARCAP was trying to promote the case as proof of UAPs being something under intelligent control, they failed and, instead, appeared to expose their research as flawed.

Quelle: SUNlite 4/2016


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Samstag, 17. September 2016 - 10:15 Uhr

Astronomie - Spechtel-Rückblick

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Da die letzte Mondbedeckung hier hinter Wolken statt fand und gedacht war auch davon Aufnahmen zu machen, kommen hier ein paar Aufnahmen von den letzten Spätsommer-Abenden:

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Schwach bildete sich noch 1Sgr auf dieser Aufnahme ab

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Fotos: ©-hjkc


965 Views

Samstag, 17. September 2016 - 10:00 Uhr

Astronomie - Forscher entdecken Echos von Schwarze Löchern

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This illustration shows a glowing stream of material from a star as it is being devoured by a supermassive black hole
This illustration shows a glowing stream of material from a star as it is being devoured by a supermassive black hole in a tidal disruption flare.
Credits: NASA/JPL-Caltech

Supermassive black holes, with their immense gravitational pull, are notoriously good at clearing out their immediate surroundings by eating nearby objects. When a star passes within a certain distance of a black hole, the stellar material gets stretched and compressed -- or "spaghettified" -- as the black hole swallows it.

 

A black hole destroying a star, an event astronomers call "stellar tidal disruption," releases an enormous amount of energy, brightening the surroundings in an event called a flare. In recent years, a few dozen such flares have been discovered, but they are not well understood.

 

Astronomers now have new insights into tidal disruption flares, thanks to data from NASA's Wide-field Infrared Survey Explorer (WISE). Two new studies characterize tidal disruption flares by studying how surrounding dust absorbs and re-emits their light, like echoes. This approach allowed scientists to measure the energy of flares from stellar tidal disruption events more precisely than ever before.

 

"This is the first time we have clearly seen the infrared light echoes from multiple tidal disruption events," said Sjoert van Velzen, postdoctoral fellow at Johns Hopkins University, Baltimore, and lead author of a study finding three such events, to be published in the Astrophysical Journal. A fourth potential light echo based on WISE data has been reported by an independent study led by Ning Jiang, a postdoctoral researcher at the University of Science and Technology of China.

 

Flares from black holes eating stars contain high-energy radiation, including ultraviolet and X-ray light. Such flares destroy any dust that hangs out around a black hole. But at a certain distance from a black hole, dust can survive because the flare's radiation that reaches it is not as intense.

 

After the surviving dust is heated by a flare, it gives off infrared radiation. WISE measures this infrared emission from the dust near a black hole, which gives clues about tidal disruption flares and the nature of the dust itself. Infrared wavelengths of light are longer than visible light and cannot be seen with the naked eye. The WISE spacecraft, which maps the entire sky every six months, allowed the variation in infrared emission from the dust to be measured.

 

Astronomers used a technique called "photo-reverberation" or "light echoes" to characterize the dust. This method relies on measuring the delay between the original optical light flare and the subsequent infrared light variation, when the flare reaches the dust surrounding the black hole. This time delay is then used to determine the distance between the black hole and the dust.

 

Van Velzen's study looked at five possible tidal disruption events, and saw the light echo effect in three of them. Jiang's group saw it in an additional event called ASASSN-14li.

 

Measuring the infrared glow of dust heated by these flares allows astronomers to make estimates of the location of dust that encircles the black hole at the center of a galaxy.

 

"Our study confirms that the dust is there, and that we can use it to determine how much energy was generated in the destruction of the star," said Varoujan Gorjian, an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, California, and co-author of the paper led by van Velzen.

 

Researchers found that the infrared emission from dust heated by a flare causes an infrared signal that can be detected for up to a year after the flare is at its most luminous. The results are consistent with the black hole having a patchy, spherical web of dust located a few trillion miles (half a light-year) from the black hole itself.

 

"The black hole has destroyed everything between itself and this dust shell," van Velzen said. "It's as though the black hole has cleaned its room by throwing flames."

JPL manages and operates WISE for NASA's Science Mission Directorate in Washington. The spacecraft was put into hibernation mode in 2011, after it scanned the entire sky twice, thereby completing its main objectives. In September 2013, WISE was reactivated, renamed NEOWISE and assigned a new mission to assist NASA's efforts to identify potentially hazardous near-Earth objects.

Quelle: NASA


1010 Views

Samstag, 17. September 2016 - 08:38 Uhr

Raumfahrt - Was passiert, wenn SpaceX Astronauten zum Mars vor NASA schickt?

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Animation of Red Dragon landing on Mars.
What Happens if SpaceX Beats NASA to Mars?

At a panel discussion Thursday about the “Journey to Mars” at the American Institute of Aeronautics and Astronautics’s annual Explore SPACE Forum, one question stood out among the rest.

What happens if SpaceX send humans to Mars before NASA?

After all, SpaceX CEO Elon Musk has been exceptionally clear about his goal to send a crewed spacecraft to the red planet by the year 2025. (It’s unclear if this vehicle would land on the surface or not, but judging by the company’s express plans to design its Red Dragon capsule as a landing craft, it’s difficult to imagine the company would avoid trying a landing attempt. In any case, a 2025 crewed mission would be way ahead of what NASA has planned.)

There are a ton of things SpaceX has to troubleshoot before a crewed mission to Mars is even close to possible — the company hasn’t even sent humans into orbityet! Still, it’s not unthinkable. 

Faced with such a prospect, William Gerstenmaier, NASA’s associate administrator for human exploration and operations, had a very astute response: “It’s not a competition.”

He went on to explain that whichever company or agency first able to make it to the red planet is irrelevant to the bigger picture of expanding the presence of humanity into deep space. “It advances us as a species,” he said. NASA is rooting for SpaceX and the success of the Red Dragon program as much as Musk and his team are rooting for NASA.

Luis Peso's depiction of Mars based on Andy Weir's book 'The Martian'.
Artist Luis Peso's depiction of Mars based on Andy Weir's book 'The Martian'.

And for good reason. NASA and SpaceX are each equipped with their own set of advantages and disadvantages. The $20 billion-ish federal agency is a powerhouse of scientific and technological expertise. In its partnership with SpaceX, NASA is able to provide the know-how for how to conduct a launch and a successful, safe spaceflight. The agency can facilitate deep space communications using existing infrastructure so that SpaceX crews can still talk to ground control. 

Unfortunately, NASA is hampered by the fact that it can’t move as fast as a private company. “If we tried to do this mission and tried to pull this together,” said Gerstenmaier, “we’d have to certify everything” and ensure 100 percent success.

But “SpaceX,” he said, “can take these risks.”

What does NASA get in return? Because SpaceX can conduct missions much faster and more frequently than NASA, they can provide the agency with essential data regarding rocket launches, descending into the Martian atmosphere, and landing on the surface of the red planet. 

And that could be a treasure trove of data. “Our plan is that at every opportunity, we would like to send a Red Dragon to Mars,” said Abhishek Tripathi, the director of the certification program at SpaceX. Partnering with NASA, he explained, is a mutual benefit all around. 

At the panel, Gerstenmaier was also able to provide insight as to why NASA is seemingly ignoring a resurrection of a lunar program — even though the moon is thought to be key to helping send astronauts to Mars.

Gerstenmaier explained that building a lunar lander and sending it to the moon’s surface would not provide any essential data on how to descend and land a spacecraft on Mars, because the moon has no atmosphere whatsoever. “It doesn’t have much play forward,” he explained.

SpaceX, having expressed no plans to send any spacecraft to the moon either, seems to feel the same way.

Quelle: INVERSE


1252 Views

Freitag, 16. September 2016 - 21:00 Uhr

Raumfahrt - Cassini beginnt Episches letzte Jahr bei Saturn

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Cassini Begins Epic Final Year at Saturn

Saturn
Since NASA's Cassini spacecraft arrived at Saturn, the planet's appearance has changed greatly. This view shows Saturn's northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017.
Credits: NASA/JPL-Caltech/Space Science Institute

After more than 12 years studying Saturn, its rings and moons, NASA's Cassini spacecraft has entered the final year of its epic voyage. The conclusion of the historic scientific odyssey is planned for September 2017, but not before the spacecraft completes a daring two-part endgame.

 

Beginning on November 30, Cassini's orbit will send the spacecraft just past the outer edge of the main rings. These orbits, a series of 20, are called the F-ring orbits. During these weekly orbits, Cassini will approach to within 4,850 miles (7,800 kilometers) of the center of the narrow F ring, with its peculiar kinked and braided structure.

 

"During the F-ring orbits we expect to see the rings, along with the small moons and other structures embedded in them, as never before," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California. "The last time we got this close to the rings was during arrival at Saturn in 2004, and we saw only their backlit side. Now we have dozens of opportunities to examine their structure at extremely high resolution on both sides."

 

The Last Act: A Grand Finale

 

Cassini's final phase -- called the Grand Finale -- begins in earnest in April 2017. A close flyby of Saturn's giant moon Titan will reshape the spacecraft's orbit so that it passes through the gap between Saturn and the rings – an unexplored space only about 1,500 miles (2,400 kilometers) wide. The spacecraft is expected to make 22 plunges through this gap, beginning with its first dive on April 27.

NASA's Cassini spacecraft stared at Saturn for nearly 44 hours in April 2016 to obtain this movie showing four Saturn days. Cassini will begin a series of dives between the planet and its rings in April 2017, building toward a dramatic end of mission -- a final plunge into the planet, six months later.
 

During the Grand Finale, Cassini will make the closest-ever observations of Saturn, mapping the planet's magnetic and gravity fields with exquisite precision and returning ultra-close views of the atmosphere. Scientists also hope to gain new insights into Saturn's interior structure, the precise length of a Saturn day, and the total mass of the rings -- which may finally help settle the question of their age. The spacecraft will also directly analyze dust-sized particles in the main rings and sample the outer reaches of Saturn's atmosphere -- both first-time measurements for the mission.

 

"It's like getting a whole new mission," said Spilker. "The scientific value of the F ring and Grand Finale orbits is so compelling that you could imagine a whole mission to Saturn designed around what we're about to do."

 

Getting Into Saturn, Literally

 

Since the beginning of 2016, mission engineers have been tweaking Cassini's orbital path around Saturn to position the spacecraft for the mission's final phase. They have sent the spacecraft on a series of flybys past Titan that are progressively raising the tilt of Cassini's orbit with respect to Saturn's equator and rings. This particular orientation enables the spacecraft to leap over the rings with a single (and final) Titan flyby in April, to begin the Grand Finale.

 

"We've used Titan's gravity throughout the mission to sling Cassini around the Saturn system," said Earl Maize, Cassini project manager at JPL. "Now Titan is coming through for us once again, providing a way for Cassini to get into these completely unexplored regions so close to the planet."

 

The Grand Finale will come to a dramatic end on Sept. 15, 2017, as Cassini dives into Saturn's atmosphere, returning data about the planet's chemical composition until its signal is lost. Friction with the atmosphere will cause the spacecraft to burn up like a meteor soon afterward.

 

To celebrate the beginning of the final year and the adventure ahead, the Cassini team is releasing a new movie of the rotating planet, along with a color mosaic, both taken from high above Saturn's northern hemisphere. The movie covers 44 hours, or just over four Saturn rotations.

Cassini infographic
The Cassini spacecraft has logged impressive numbers in the 12 years since it arrived at Saturn on July 1, 2004. This infographic offers a snapshot of just a few of the mission's big numbers on Sept. 15, 2016, as it heads into a final year of science at Saturn.
Credits: NASA/JPL-Caltech

‘A Truly Thrilling Ride’

 

"This is the sort of view Cassini will have as the spacecraft repeatedly climbs high above Saturn's northern latitudes before plunging past the outer -- and later the inner -- edges of the rings," said Spilker.

 

And so, although the mission's end is approaching -- with a "Cassini Final Plunge" clock already counting down in JPL mission control -- an extremely important phase of the mission is still to come.

 

"We may be counting down, but no one should count Cassini out yet," said Curt Niebur, Cassini program scientist at NASA Headquarters in Washington. "The journey ahead is going to be a truly thrilling ride." 

 

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.

Quelle: NASA


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