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Sonntag, 31. März 2013 - 23:15 Uhr

Astronomie - Plancks Vermächtnis offenbart uns ein fast perfektes Universum und sein Alter!

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22.03.2013

Kosmische Mikrowellen-Hintergrundstrahlung aus der Sicht von Planck
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Heute wurde die bisher genaueste Karte der kosmischen Mikrowellen-Hintergrundstrahlung, der fossilen Strahlung aus der Zeit des Urknalls, vorgestellt. Die ihr zugrunde liegenden Daten wurden mit dem Weltraumteleskop Planck der Europäischen Weltraumorganisation ESA erfasst. Einige der mit dieser Karte gewonnenen Erkenntnisse rütteln an den Grundfesten unseres derzeitigen Verständnisses des Weltalls.  
Das Bild basiert auf den Daten der ersten sich über 15,5 Monate erstreckenden Beobachtungen von Planck. Es stellt die erste, den gesamten Himmel umfassende Abbildung der ältesten Lichtstrahlung im All dar, die ihren Abdruck am Sternenhimmel zu einer Zeit hinterließ, als unser Universum gerade 380 000 Jahre alt war. 
 
Zu diesem Zeitpunkt bildete das Universum eine heiße, dichte Suppe aus zueinander in Wechselwirkung stehenden Protonen, Elektronen und Photonen bei einer Temperatur von etwa 2700 °C. Als Protonen und Elektronen sich zu Wasserstoffatomen formten, wurde das Licht freigesetzt. Durch die Ausdehnung des Universums wurde auch dieses Licht bis heute auf Mikrowellen-Wellenlängen ausgedehnt und besitzt eine Temperatur von gerade einmal 2,7 Grad über dem absoluten Nullpunkt. 
 
Die kosmische Mikrowellen-Hintergrundstrahlung weist jedoch winzige Temperaturunterschiede auf, die sich mit Regionen von geringfügig abweichender Dichte in der Frühzeit des Universums decken und so den Keim für alle künftigen Strukturen, nämlich die heutigen Sterne und Galaxien, in sich tragen. 
 
Dem kosmologischen Standardmodell zufolge entstanden diese Fluktuationen unmittelbar nach dem Urknall und wurden dann innerhalb eines kurzen Zeitraums beschleunigter Expansion, auch Inflation genannt, auf kosmologische Ausmaße ausgedehnt. 
 
Planck wurde konzipiert, um diese Fluktuationen des gesamten Sternenhimmels mit bisher unerreichter Auflösung und Empfindlichkeit zu erfassen. Die Analyse der Eigenschaften und der Verteilung dieser Urstrukturen auf dem Planck-Bild der kosmischen Mikrowellen-Hintergrundstrahlung ermöglicht uns Rückschlüsse in Bezug auf die Zusammensetzung und Entwicklung des Universums von seiner Entstehung bis zum heutigen Tag.
Insgesamt stellen die mit der neuen Planck-Karte gewonnenen Erkenntnisse eine eindeutige und zudem die bisher präziseste Bestätigung des kosmologischen Standardmodells dar und setzen so neue Richtwerte für unser Bild von der Zusammensetzung des Universums. 
 
Dank der außerordentlichen Präzision der Planck-Karte konnten jedoch auch einige bisher ungeklärte Phänomene aufgedeckt werden, für deren Verständnis neue physikalische Erklärungsversuche erforderlich sein könnten. 
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„Die herausragende Qualität dieses Porträts, das uns Planck von einem noch in seinen Kinderschuhen stehenden All gezeichnet hat, ermöglicht uns, Schicht für Schicht bis zu seinem Ursprung vorzudringen, und macht uns gleichzeitig deutlich, dass unsere bisherige Vorstellung vom Kosmos alles andere als vollkommen ist. Voraussetzung für diese Entdeckungen waren die einzigartigen Technologien, die europäische Unternehmen für diese Mission entwickelt haben“, so ESA-Generaldirektor Jean-Jacques Dordain. 
 
„Seit 2010, als Plancks erstes den gesamten Himmel erfassendes Bild veröffentlicht wurde, waren wir damit beschäftigt, die Emissionen im Vordergrund, die den Blick auf das erste Licht des Universums bisher verstellt hatten, vorsichtig herausfiltern und zu analysieren, so dass sich die kosmische Mikrowellen-Hintergrundstrahlung uns nun in ihren kleinsten, bisher unerkannten Details offenbart“, erläutert George Efstathiou von der Universität Cambridge. 
 
Zu den wohl überraschendsten Ergebnissen zählt die Tatsache, dass die Fluktuationen bei den Temperaturen der Hintergrundstrahlung auf großen Winkelskalen nicht den im Standardmodell vorhergesagten Werten entsprechen: Ihre Signale sind nicht so stark, wie dies von der von Planck entdeckten kleinmaßstäbigeren Struktur zu erwarten gewesen wäre.
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PLANCK ENHANCED ANOMALIES
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Ebenfalls verblüffend ist die Asymmetrie der Durchschnittstemperaturen an den entgegengesetzten Hemisphären des Himmels. Dies widerspricht der im Standardmodell postulierten grundsätzlichen Ähnlichkeit des Universums, ganz gleich in welche Richtung man blickt. 
 
Darüber hinaus erstreckt sich ein kalter Fleck über ein Areal am Himmel, das wesentlich größer ist als erwartet. 
 
Bereits Plancks Vorgänger, die NASA-Mission WMAP, gab Hinweise auf die Asymmetrie und den kalten Fleck, jedoch schenkte man ihnen aufgrund der Zweifel an ihrem kosmischen Ursprung kaum Beachtung. 
 
„Die eindeutige Erfassung dieser Anomalien durch Planck lässt keine weiteren Zweifel an ihrer Existenz zu. Sie können nun nicht mehr als Messfehler betrachtet werden. Wir müssen sie als Tatsachen hinnehmen und nun nach einer plausiblen Erklärung suchen“, bekräftigt Paolo Natoli von der italienischen Universität Ferrara. 
 
„Stellen Sie sich vor, Sie untersuchen das Fundament eines Hauses und stellen dabei einige Schwachstellen fest. Auch wenn Sie nicht sagen können, ob diese das Haus irgendwann zum Einsturz bringen, werden Sie zumindest versuchen, möglichst rasch neue Stützen zu errichten“, erklärte bildlich François Bouchet vom Pariser Institut für Astrophysik. 
 
Eine mögliche Erklärung für diese Anomalien wäre die Hypothese, dass das All in Wirklichkeit in einer größeren als der von uns beobachtbaren Skala nicht nach allen Richtungen hin gleich geartet ist. In diesem Szenario hätte das Licht der Hintergrundstrahlung einen wohl etwas komplizierteren Weg durch das Universum als bisher gedacht zurücklegen müssen, was zu einigen der ungewöhnlichen Beobachtungsergebnisse führen würde. 
 
„Unser Fernziel sollte es sein, ein neues Modell zu entwerfen, das die Anomalien nicht nur vorhersagt, sondern auch zueinander in Beziehung setzt. Wir befinden uns jedoch gerade erst am Anfang und können noch nicht sagen, ob dies überhaupt möglich sein wird und welche neuen physikalischen Erklärungsversuche hierzu nötig wären. Es wird auf jeden Fall spannend“, freut sich Professor Efstathiou.
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Ein neuer kosmischer Bauplan
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Von diesen Anomalien abgesehen stehen die Planck-Daten jedoch in erstaunlicher Übereinstimmung mit dem erwarteten, relativ einfachen Modell des Universums und ermöglichen den Wissenschaftlern, die einzelnen Steine seines Bauplans nun auch bis ins kleinste Detail zu beschreiben. 
 
Die normale Materie, aus der Sterne und Galaxien bestehen, macht lediglich 4,9 % der Masse-/Energiedichte des Alls aus. Dunkle Materie, die bisher nur indirekt über den Einfluss ihrer Schwerkraft nachgewiesen werden konnte, ist mit einem Anteil von 26,8 % vertreten, also um fast ein Fünftel mehr als bisher angenommen. 
 
Die dunkle Energie hingegen, eine rätselhafte Kraft, die für die immer schnellere Ausdehnung des Universums verantwortlich gemacht wird, fällt weniger ins Gewicht als in den bisherigen Schätzungen. 
 
Zu guter Letzt lässt sich anhand der Planck-Daten auch ein neuer Wert für die Hubble-Konstante ermitteln, d. h. der Geschwindigkeit, mit der sich das Universum heute ausdehnt, nämlich 67,15 km/s/Megaparsec. Dies liegt deutlich unter dem derzeitigen, in der Astronomie verwendeten Standardwert. Aus diesen Daten lässt sich für das All auf ein Alter von 13,82 Milliarden Jahren zurückschließen. 
 
„Mit diesen bisher präzisesten und ausführlichsten Karten des Himmelszelts im Mikrowellenspektrum schafft Planck ein neues Bild vom Universum und führt uns gleichzeitig an die Grenzen unseres Wissens, was die aktuellen kosmologischen Theorien angeht“, so Jan Tauber, ESA-Projektwissenschaftler für Planck. 
 
„Wir stellen eine erstaunliche Übereinstimmung mit dem kosmologischen Standardmodell fest, wenn auch einige rätselhafte Phänomene uns keine andere Wahl lassen, als gewisse grundsätzliche Annahmen zu überdenken. Wir stehen erst am Anfang eines neuen Unterfangens und sind zuversichtlich, dass unsere kontinuierlichen Studien der Planck-Daten weiteres Licht auf diese Rätsel werfen werden.“
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PLANCK FIRST LIGHT SURVEY
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Quelle: ESA
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Update: 31.03.2013
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Wissenschaftler haben eine nie dagewesene Karte vom ersten Licht des Universums erarbeitet - mit dem Weltraumteleskop Planck der Europäischen Raumfahrtbehörde ESA. Die Raumsonde hat einige überraschende Daten geliefert und damit gravierende Fragen zum Urknall aufgeworfen.

Jan Tauber von der ESA sagt, die Karte gebe ein Bild des "kosmischen Mikrowellen-Hintergrunds". Diese Hintergrundstrahlung ist Licht - oder Wärme, und die wurde nur 380.000 Jahre nach dem Urknall emittiert, als Licht und Materie eng gekoppelt waren. Deshalb gibt uns die Licht-Kartierung wichtige Auskunft über die Struktur des jungen Universums. Tauber erklärt die Karte: 

"Ein orangefarbener oder blauer Punkt - das sind Punkte in Entwicklung. Sie repräsentieren eine zu der Zeit etwas höhere beziehungsweise etwas geringere Dichte der Materie. Sie werden sich weiter entwickeln und immer dichter oder weniger dicht werden. Sie werden sich zu den Strukturen entwickeln, die wir heute haben. Sie werden sich zu Sternen entwickeln, und diese werden Galaxien bilden, die sich wiederum zu Galaxienhaufen formieren werden."
 
Tauber sagt, der größte Teil der Karte entspreche durchaus dem geltenden Modell, aber zugleich habe man mit dem Raumteleskop "merkwürdige Dinge" festgestellt, wie etwa "kalte Flecken", also strahlungsarme Stellen, wo sie nach geltender Auffassung nicht vorkommen dürften.
 
Bruce Partridge, Professor für Astronomie am Haverford College in Boston, hat schon früh zu dem Projekt beigetragen. Ihm war klar, dass Bilder in nie dagewesener Auflösung vonnöten waren, um dem Urknall näherzukommen, und dies sei mit dem Weltraumteleskop Planck gelungen. Dabei mussten verschiedene störende Einflüsse berücksichtigt werden:
 
"Wir leben in einer Galaxis, die selbst Wärmestrahlung abgibt. Die kann die vom Urknall übriggebliebene Wärme stören oder simulieren. Das muss man kontrollieren."
 
Das gelte auch für Hintergrundstrahlungsquellen. Alle diese Wirkungen waren auszublenden, um "an das kosmische Signal vom heißen Urknall zu gelangen."
 
Die Wissenschaftler sähen durch die neuen Daten eine fundamentale Theorie in Frage gestellt, sagt George Efstathiou, Professor für Astrophysik in Cambridge: Nach dieser sogenannten Inflationstheorie gab es bei der Entstehung des Universums eine Phase, in der es sich mit mehr als Lichtgeschwindigkeit beschleunigte, "sodass ein winziger Fleck unglaublich schnell expandieren konnte." Nun aber sehe man "seltsame Muster", die nicht in diese Theorie passten:
 
"Es ist also durchaus möglich, dass wir ein unvollständiges Bild haben. Und es könnte sein, dass wir uns geirrt haben, dass es die Inflation garnicht gegeben hat. Es ist gut möglich, dass es eine Phase des Universums vor dem Urknall gegeben hat, und dass man die Geschichte des Universums in eine Vor-Urknall-Zeit zurückverfolgen kann."
 
In diesen neuen Entdeckungen der Planck-Mission liegt für Efstathiou "das Potential für einen Paradigmenwandel" der Physik. Noch zeichne sich keine Theorie ab, in die man gerade festgestellten Anomalien zwanglos einfügen könne. "Wenn es aber einmal so weit ist, dass eine Theorie erscheint, die diese bislang unverbundenen Phänomene in einen einheitlichen theoretischen Zusammenhang bringt, dann weist sie den Weg in eine neue Physik."
 
Tauber betont, dass frühere Beobachtungen, etwa Messungen der Expansion des Universums, durchaus nicht in Frage gestellt seien. "Was sich ändert, ist unsere Auffassung vom Beginn des Universums, von den Vorgängen ganz am Anfang, beim sogenannten Urknall."
 
Auch Partridge bekräftigt die Solidität der Antworten der Wissenschaft auf fundamentale Fragen: "Wie alt ist das Universum? Expandiert es wirklich? Begann es mit einem heißen Urknall? Und die Anworten auf diese Fragen kommen aus diesen Beobachtungen. Ja, am Anfang war ein heißer Urknall. Und wir kennen das Alter: 13,7 Milliarden Jahre, nicht 14 oder 15, sondern 13,7 Milliarden. Diese Antworten beruhen auf Beobachtungen. Die Fragen haben die Menschheit seit Jahrtausenden beschäftigt. Und nun, in meinen Lebzeiten, werden sie beantwortet. Es sind scharfe, präzise, physikalische und auf Beobachtung beruhende Antworten."
 
Und schließlich noch einmal Efstathiou: "Zwar haben wir schöne Versuchsergebnisse, die unseren einfachen Modellen von den Vorgängen beim Urknall entsprechen, aber sie entsprechen ihnen nicht ganz genau. Und so ist es wohl nicht überraschend, dass wir mit unserer Physik, die das erklären soll, noch nicht ganz fertig sind. Das heißt einfach: Es gibt in der Zukunft noch viel zu tun!"

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Quelle: ESA


Tags: Planck Universum 

3185 Views

Sonntag, 31. März 2013 - 16:00 Uhr

Mars-Chroniken - Mars-Rover Opportunity Sol 071-085 Rückblick

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 71 of Opportunity's mission to Meridiani Planum at approximately 15:12:09 Mars local solar time, camera commanded to use Filter 2 (753 nm). NASA/JPL/Cornell

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 71 of Opportunity's mission to Meridiani Planum at approximately 14:46:50 Mars local solar time, camera commanded to use Filter 2 (753 nm). NASA/JPL/Cornell

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 71 of Opportunity's mission to Meridiani Planum at approximately 13:21:29 Mars local solar time, camera commanded to use Filter 2 (753 nm). NASA/JPL/Cornell

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 71 of Opportunity's mission to Meridiani Planum at approximately 14:08:29 Mars local solar time. NASA/JPL

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 71 of Opportunity's mission to Meridiani Planum at approximately 14:06:17 Mars local solar time. NASA/JPL

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 72 of Opportunity's mission to Meridiani Planum at approximately 13:31:46 Mars local solar time. NASA/JPL

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 72 of Opportunity's mission to Meridiani Planum at approximately 13:29:32 Mars local solar time. NASA/JPL

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Left Front Hazard Camera Non-linearized Full frame EDR acquired on Sol 72 of Opportunity's mission to Meridiani Planum at approximately 15:29:47 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 73 of Opportunity's mission to Meridiani Planum at approximately at approximately 13:58:58 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Front Hazard Camera Non-linearized Full frame EDR acquired on Sol 73 of Opportunity's mission to Meridiani Planum at approximately 15:03:01 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 74 of Opportunity's mission to Meridiani Planum at approximately 11:52:20 Mars local solar time, camera commanded to use Filter 4 (601 nm). NASA/JPL/Cornell

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 74 of Opportunity's mission to Meridiani Planum at approximately 12:27:10 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 80 of Opportunity's mission to Meridiani Planum at approximately at approximately 11:27:23 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 80 of Opportunity's mission to Meridiani Planum at approximately 12:15:07 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Right Front Hazard Camera Non-linearized Downsampled EDR acquired on Sol 80 of Opportunity's mission to Meridiani Planum at approximately 11:47:43 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 81 of Opportunity's mission to Meridiani Planum at approximately 10:38:35 Mars local solar time, camera commanded to use Filter 5 (535 nm). NASA/JPL/Cornell

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Left Rear Hazard Camera Non-linearized Full frame EDR acquired on Sol 81 of Opportunity's mission to Meridiani Planum at approximately 13:25:02 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 82 of Opportunity's mission to Meridiani Planum at approximately 15:11:40 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 82 of Opportunity's mission to Meridiani Planum at approximately 14:58:36 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Downsampled EDR acquired on Sol 83 of Opportunity's mission to Meridiani Planum at approximately 15:56:11 Mars local solar time, camera commanded to use Filter 6 (482 nm). NASA/JPL/Cornell

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 83 of Opportunity's mission to Meridiani Planum at approximately 13:56:19 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Left Navigation Camera Non-linearized Full frame EDR acquired on Sol 83 of Opportunity's mission to Meridiani Planum at approximately 15:49:22 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 84 of Opportunity's mission to Meridiani Planum at approximately at approximately 13:29:39 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 84 of Opportunity's mission to Meridiani Planum at approximately 10:44:51 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 84 of Opportunity's mission to Meridiani Planum at approximately 14:51:13 Mars local solar time. NASA/JPL

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Left Rear Hazard Camera Non-linearized Full frame EDR acquired on Sol 84 of Opportunity's mission to Meridiani Planum at approximately 14:49:46 Mars local solar time. NASA/JPL

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Left Front Hazard Camera Non-linearized Full frame EDR acquired on Sol 84 of Opportunity's mission to Meridiani Planum at approximately 14:03:26 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 13:20:44 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Right Panoramic Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 13:14:15 Mars local solar time, camera commanded to use Filter 1 (436 nm). NASA/JPL/Cornell

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 13:07:58 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Left Navigation Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 14:24:41 Mars local solar time. NASA/JPL

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Left Navigation Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 11:08:27 Mars local solar time. NASA/JPL

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Left Rear Hazard Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 14:22:03 Mars local solar time. NASA/JPL

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Left Front Hazard Camera Non-linearized Full frame EDR acquired on Sol 85 of Opportunity's mission to Meridiani Planum at approximately 14:21:14 Mars local solar time. NASA/JPL

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Fotos: NASA


Tags: Mars-Rover Opportunity Sol 071-085 

2914 Views

Sonntag, 31. März 2013 - 11:20 Uhr

Mars-Chroniken - SwRI Studie findet flüssiges Wasser welches über und unter gefroren Alaska Sanddünen fliest, Hinweise auf einen feuchteren Mars

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San Antonio — March 28, 2013 — The presence of liquid water at and beneath frozen Alaskan sand dunes during Arctic winter suggests that liquid water could also be temporarily stable (or metastable) at frost-covered sand dunes on Mars.

 

A team of earth and planetary scientists from Southwest Research Institute (SwRI) performed field studies of the Great Kobuk Sand Dunes, which serve as an Earth-based cold-climate "analog" to dunes on the Red Planet. The team conducted fieldwork in Kobuk Valley National Park, Alaska, when the average daily surface temperature was -14.7 degrees C (5.5 degrees F). Geophysical data gathered by SwRI scientists strongly suggest there is a perched layer of liquid water in the dunes occurring just below the seasonally frozen active layer.

 

While conducting this planetary analog study, the scientists also noticed that several melt-water debris flows had formed on sunward-facing dune slopes. At one location, ground surface temperature measured nearby was within 1 degree C of the thaw point for fewer than 10 minutes. During an even colder period at another dune location, ground surface temperatures measured near active debris flows never approached the thaw point. The scientists surmise that patches of dark sand on bright white snow enabled highly localized thawing.

 

"Debris flows with gully or erosion tracks also appear on the slopes of several dune fields on Mars. Very few minutes of above-freezing temperatures are needed to locally melt water and mobilize sand transport down steep slopes," said hydrogeologist Dr. Cynthia Dinwiddie, a principal engineer in SwRI's Geosciences and Engineering Division.

 

These phenomena occur at temperatures corresponding to those observed on the surface of Mars, Dinwiddie said.

 

"Recent measurements of air temperature and pressure recorded by the Mars Science Laboratory on the Curiosity Rover, which landed in Gale Crater last August, suggest that liquid water potentially would be stable there during the warmest portion of each day," said Dinwiddie.

 

Liquid water, solid ice and water vapor can coexist in stable equilibrium at what is called the triple point of water. Late-winter to early-spring environmental conditions at the Great Kobuk Sand Dunes are sufficiently similar to conditions on Mars that these Alaskan dunes can serve as an informative planetary analog, Dinwiddie said.

 

The Grand Kobuk Sand Dunes project was supported by NASA's Mars Fundamental Research Program and SwRI's internal research program.

Quelle: Southwest Research Institute (SwRI)


3210 Views

Sonntag, 31. März 2013 - 11:00 Uhr

Raumfahrt - China startet im April High-Res Erdbeobachtungssatelliten

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BEIJING -- China will launch the first satellite for its high-resolution system for Earth observation in April, a government agency revealed Thursday.

Examinations of the satellite and its carrier rocket, the Long March 2D, have been completed and the satellite is now in the launch stage, according to the State Administration of Science, Technology and Industry for National Defense (SATIND).

China plans to launch five to six satellites before the end of 2015 in order to build a spatial, temporal and spectral high-resolution observation system.

The system will mainly provide services for the Ministry of Land and Resources, Ministry of Agriculture and Ministry of Environmental Protection, and is expected to help reduce disasters, protect resources,the environment and national security, as well as support geographic and oceanic surveys and urban transportation management, the SATIND said.

It will also enhance China's ability to obtain high-resolution observation data and accelerate its development of satellite application technologies, the SATIND said.

Quelle: CHINADAILY


2960 Views

Samstag, 30. März 2013 - 15:20 Uhr

Mars-Chroniken - Mars-Rover Opportunity Sol 061-070 Rückblick

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 61 of Opportunity's mission to Meridiani Planum at approximately at approximately 11:37:09 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Right Navigation Camera Non-linearized Downsampled EDR acquired on Sol 61 of Opportunity's mission to Meridiani Planum at approximately 14:00:46 Mars local solar time. NASA/JPL

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Left Navigation Camera Non-linearized Full frame EDR acquired on Sol 61 of Opportunity's mission to Meridiani Planum at approximately 11:43:49 Mars local solar time. NASA/JPL

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Left Front Hazard Camera Non-linearized Full frame EDR acquired on Sol 61 of Opportunity's mission to Meridiani Planum at approximately 15:44:12 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 62 of Opportunity's mission to Meridiani Planum at approximately at approximately 13:03:54 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 62 of Opportunity's mission to Meridiani Planum at approximately 14:43:14 Mars local solar time, camera commanded to use Filter 5 (535 nm). NASA/JPL/Cornell

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 62 of Opportunity's mission to Meridiani Planum at approximately 13:49:43 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 63 of Opportunity's mission to Meridiani Planum at approximately at approximately 11:41:00 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 63 of Opportunity's mission to Meridiani Planum at approximately 14:21:52 Mars local solar time, camera commanded to use Filter 7 (432 nm). NASA/JPL/Cornell

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Left Rear Hazard Camera Non-linearized Full frame EDR acquired on Sol 63 of Opportunity's mission to Meridiani Planum at approximately 14:36:11 Mars local solar time. NASA/JPL

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Left Panoramic Camera Non-linearized Full frame EDR acquired on Sol 68 of Opportunity's mission to Meridiani Planum at approximately 12:59:34 Mars local solar time, camera commanded to use Filter 4 (601 nm). NASA/JPL/Cornell

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Left Navigation Camera Non-linearized Downsampled EDR acquired on Sol 68 of Opportunity's mission to Meridiani Planum at approximately 15:03:05 Mars local solar time. NASA/JPL

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Microscopic Imager Non-linearized Full frame EDR acquired on Sol 69 of Opportunity's mission to Meridiani Planum at approximately at approximately 13:27:28 Mars local solar time, Microscopic Imager dust cover commanded to be OPEN. NASA/JPL/Cornell/USGS

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Left Front Hazard Camera Non-linearized Downsampled EDR acquired on Sol 69 of Opportunity's mission to Meridiani Planum at approximately 11:50:48 Mars local solar time. NASA/JPL

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Right Navigation Camera Non-linearized Full frame EDR acquired on Sol 70 of Opportunity's mission to Meridiani Planum at approximately 13:18:14 Mars local solar time. NASA/JPL

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Left Rear Hazard Camera Non-linearized Full frame EDR acquired on Sol 70 of Opportunity's mission to Meridiani Planum at approximately 11:50:00 Mars local solar time. NASA/JPL

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Fotos: NASA


653 Views

Samstag, 30. März 2013 - 13:06 Uhr

Raumfahrt -USAF startet WGS-5 an Bord einer Delta IV am 8. Mai

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LOS ANGELES AIR FORCE BASE, El Segundo, Calif. -- The launch of the U.S. Air Force's Wideband Global SATCOM mission on a United Launch Alliance Delta IV vehicle has been placed on the 45th Space Wing range schedule for May 8.

The launch vehicle and spacecraft are both being processed in Florida.

The investigation into the off-nominal performance on the Global Positioning System IIF-3 launch last October is still progressing. Final testing related to the investigation is underway. ULA, Pratt Whitney Rocketdyne, and the Air Force have been working closely on this investigation and have approved processing this mission toward the May 8 launch date. Launch officials have planned investigation closure reviews in mid-April.

Quelle: USAF

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Quelle: ULA


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Samstag, 30. März 2013 - 12:30 Uhr

Mars-Chroniken - Folgen Sie dem Wasser? Nein, Folgen Sie dem Mars Salz

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Foto: Opportunity - NASA

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This article originally appeared in The Mars Society’s The Mars Quarterly. As part of AmericaSpace’s partnership with The Mars Society, they publish stories produced by our staff first and then they are re-posted on AmericaSpace.

You may be familiar with the phrase “follow the water” when it comes to the search for life on Mars, and for good reason—any place on Earth where there is liquid water, there is life. So, logically, the best places to look for evidence of past or present life on Mars would be where there has been liquid water in the past (or perhaps even still is, underground). But now there is also another approach being taken, in terms of possible present-day habitability in particular: follow the salt.

For a long time now, it has been postulated that liquid water might still be possible on Mars today—thanks to salts. From the various lander and rover missions, it is already known that salts such as perchlorates are common and widespread on Mars. Bright deposits have even been churned up from just below the surface by the rovers’ wheels (see image above). These deposits are evidence for liquid water on or near the Martian surface in the distant past. But what about the present?

On Mars’ surface, it is too cold (most of the time) and the air is too thin to normally support liquid water. But water with a high salt content—i.e. brines—can remain liquid under lower atmospheric pressures and in lower temperatures than pure liquid water can. To scientists, the perchlorate salts are an exciting discovery. As Chris McKay from NASA Ames Research Center puts it, “I would say it is probably the most important astrobiological discovery since Viking—the discovery of perchlorate.” The perchlorates could explain why the Viking landers in the 1970s failed to find any organics in the soil, even though the other life-detection tests (for microbes) gave seemingly positive results. When the soil was heated, the perchlorates would have reacted to destroy any organics present.

Salts could also help the soil to better retain water absorbed from the atmosphere—a process called deliquescence. This would be very beneficial for any putative microorganisms, as more moisture would be retained during more humid periods.

But these salts may also have other implications for possible microbial life; if there are any pockets of liquid water still underground in places, they might provide an ideal niche for life to survive. Such briny water can be very inhospitable for most life forms, except perhaps for some extremophiles. But on a dry planet like Mars, any water might be better than no water at all.

As it turns out, these brines may have already been observed directly from orbit. The Mars Reconnaissance Orbiter has found several locations where briny water seems to be coming to the surface from below. These dark streaks flow downward on sun-facing slopes; known as recurring slope lineae, these streaks are seasonal in appearance and always form on such warmer slopes. Briny water is still considered to be the best explanation, noting that these type of streaks are different from others thought to be caused by dry dust avalanches. It is also thought possible that some less toxic salts, other than perchlorates, may be involved.

This discovery has changed ideas about the best ways to search for evidence of life on Mars. David Page from the University of California sums it up this way: “I’m struck by how different this discussion is than just a few years ago. There are clearly places that water activity does appear to be occurring on Mars.” And as Alfred McEwen from the University of Arizona adds, “Now we have some very strong ideas about where to go and what to look for.”

It is also possible that non-salty water may still exist on Mars, deeper below the surface where temperatures would be warmer. Subsurface aquifers would indeed be an exciting find. Either way, given all of the new evidence we now have, it would seem prudent to follow both the salt and water, in the quest to discover past or present Martian life.


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Samstag, 30. März 2013 - 12:00 Uhr

Raumfahrt - Energia´s Asteroiden-Abwehr-Vorschlag

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BAIKONUR, An ultra-heavy booster is needed to be created in order to prevent the Earth from asteroids and comets, head of the Russian space rocket corporation, Energia, Vitaly Lopota said on Friday.

The booster should be designed on the basis of the existing flying components, which have been created within the Energia booster program, Lopota said. “Such booster will be able to carry and deploy detection and tracking system elements [a thermonuclear warhead if it necessary] near dangerous space facilities,” the corporation’s head explained.

He noted that the Energia Corporation considered it necessary to develop Russia’s system to monitor asteroids. “We propose to fulfil this task by using three spacecraft deployed in the Langrage points in the Earth-Moon system,” Lopota said.

At the same time, he said, “The ISS [International Space Station] should be used as the base to practise technology and cooperation.”

In his view, in order to resolve this issue different organisations and enterprises should maintain cooperation, including on the international arena. “Domestic and foreign space organizations, institutes and companies with which we develop cooperation show interests in our proposals,” Lopota stressed.

Quelle: Itar-Tass


3162 Views

Freitag, 29. März 2013 - 14:00 Uhr

Mars-Curiosity-Chroniken - Curiosity-News Sol 226-228

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 226 (2013-03-26 07:42:31 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 226 (2013-03-26 07:49:21 UTC).

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This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 226 (2013-03-26 07:19:42 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 10:58:23 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 11:39:56 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 11:34:43 UTC).

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This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 08:04:15 UTC).

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This image was taken by Navcam: Right B (NAV_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 11:36:22 UTC).

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This image was taken by Front Hazcam: Left B (FHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 227 (2013-03-27 05:37:44 UTC).

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This image was taken by Rear Hazcam: Left B (RHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 228 (2013-03-28 06:17:45 UTC).

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Fotos: NASA


Tags: Curiosity-News Sol 226-228 

3105 Views

Freitag, 29. März 2013 - 12:55 Uhr

Mars-Curiosity-Chroniken - Curiosity hat zwei Arten von Modellierung bei Untergrund Wasser

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Variation in Subsurface Water In 'Yellowknife Bay'

The image, at lower left, is annotated to show where the Dynamic Albedo of Neutrons (DAN) instrument on NASA's Mars rover Curiosity took measurement on a rock outcrop (Spot 39) and on loose soil (Spot 40) within the "Yellowknife Bay' area of Mars' Gale Crater.

The graph, at upper right, and the table, at lower right, show that the DAN measurements indicated more water in the subsurface at the loose-soil spot than at the rock outcrop. DAN detects even very small amounts of water in the ground beneath the rover, primarily water bound into the crystal structure of hydrated minerals.

The image at lower left was taken by the rover's Mast Camera (Mastcam).

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Variation in Water Content in Martian Subsurface Along Curiosity's Traverse

This set of graphs shows variation in the amount and the depth of water detected beneath NASA's Mars rover Curiosity by use of the rover's Dynamic Albedo of Neutrons (DAN) instrument at different points along the distance the rover has driven, in meters.

DAN detects even very small amounts of water in the ground beneath the rover, primarily water bound into the crystal structure of hydrated minerals. The bottom graph indicates that the water content of the top 2 feet (60 centimeters) of the ground at points in the "Yellowknife Bay" area where DAN has taken measurements is estimated at about 3 percent.

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Bluish Color in Broken Rock in 'Yellowknife Bay'

The Mast Camera (Mastcam) on NASA's Mars rover Curiosity showed researchers interesting internal color in this rock called "Sutton_Inlier," which was broken by the rover driving over it. The Mastcam took this image during the 174th Martian day, or sol, of the rover's work on Mars (Jan. 31, 2013). The rock is about 5 inches (12 centimeters) wide at the end closest to the camera. This view is calibrated to estimated "natural" color, or approximately what the colors would look like if we were to view the scene ourselves on Mars. The inside of the rock, which is in the "Yellowknife Bay" area of Gale Crater, is much less red than typical Martian dust and rock surfaces, with a color verging on grayish to bluish.

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Drill Hole Image and Spectra Acquired by Mastcam

This set of images illustrates how the science filters of the Mast Camera (Mastcam) on NASA's Mars rover Curiosity can be used to investigate aspects of the composition and mineralogy of materials on Mars. On the left is an estimated "natural" color view of Curiosity's full drill hole and mini-drill hole within the "John Klein" outcrop in "Yellowknife Bay" on Sol 183 (Feb. 9, 2013). Natural color simulates approximately what the colors would look like if we were to view the scene ourselves on Mars. On the right is the result of plotting the calibrated level of reflectance (the percentage of incident sunlight that is reflected off the surface) of each of the indicated areas of the image as a function of wavelength (color).

The wavelengths correspond to the Mastcam science filters plus the red, green and blue wavelengths of the Mastcam Bayer filters (for a total of 12 unique wavelengths between the two Mastcam cameras). The six filters at the lower wavelengths are within the range of typical human color vision, while the six filters at the higher wavelengths represent infrared colors that our eyes are not sensitive to, but which the Mastcams can detect.

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Comparing Mastcam and Laboratory Spectra

This set of images illustrates how the science filters of the Mast Camera (Mastcam) on NASA's Mars rover Curiosity can be used to investigate aspects of the composition and mineralogy of materials on Mars. On the left is a set of laboratory spectra of some iron oxide minerals (red and orange curves) and some relatively unoxidized minerals from typical basaltic volcanic rocks: pyroxenes (green and blue curves). On the right is the result of plotting the calibrated level of reflectance (the percentage of incident sunlight that is reflected off the surface) of several distinct regions from the Sol 183 (Feb. 9, 2013) Mastcam image of drill holes at rock target "John Klein" as a function of wavelength (color).

The wavelengths correspond to the Mastcam science filters plus the red, green and blue wavelengths of the Mastcam Bayer filters, for a total of 12 unique wavelengths between the two Mastcam cameras. The six filters at the lower wavelengths are within the range of typical human color vision, while the six filters at the higher wavelengths represent infrared colors that our eyes are not sensitive to, but which the Mastcams can detect.

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Variations of DAN measurements along Curiosity traverse

This chart graphs measurements made by the Dynamic Albedo of Neutrons (DAN) instrument on NASA's Mars rover Curiosity against the distance the rover has driven, in meters.

In active mode, DAN shoots neutrons into the ground and senses how they are reflected. Neutrons that collide with hydrogen atoms bounce off with a characteristic decrease in energy. By measuring the energies of the reflected neutrons, DAN can detect the fraction that was slowed in these collisions, and therefore the amount of hydrogen. In the passive mode, DAN does not shoot neutrons into the ground, but relies on galactic cosmic rays as a source of neutrons that are reflected by subsurface hydrogen and detected by DAN.

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Two Types of Modeling of Subsurface Water

The Dynamic Albedo of Neutrons (DAN) instrument on NASA's Mars rover Curiosity detects even very small amounts of water in the ground beneath the rover, primarily water bound into the crystal structure of hydrated minerals. This graphic presents two types of modeling for how much of the detected water is very close to the surface and how much is deeper within the top 20 inches (half meter). At most places where the rover has made DAN measurements, the best fit for the data is one with less water in the upper layer than in the lower layer.

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Filters for Color Imaging and for Science

The color cameras on NASA's Mars rover Curiosity, including the pair that make up the rover's Mast Camera (Mastcam) instrument, use the same type of Bayer pattern RGB filter as found in typical commercial color cameras. Bayer filtering means that the charge-coupled device (CCD) that detects each pixel of the image is covered with a grid of green, red and blue filters so that the camera gets the three color components of the entire scene in a single exposure. Electronics inside the camera can then merge the separate sets of color pixels into a single full-color image.

Besides the affixed red-green-blue filter grid, the Mastcam cameras also each have an eight-position filter wheel with specialized science filters between the camera optics and the CCD. The wheel can be rotated to choose one of these narrow-waveband filters, in the visible-light or infrared parts of the spectrum, or no filter at all. Each camera's filter wheel holds six science filters that, between both cameras, can yield images in nine unique wavelengths from the deep blue (445 nanometers) to the short-wave near-infrared (1012 nanometers). One additional science filter in each wheel is specially designed to enable direct imaging of the sun.

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'Raw,' 'Natural' and 'White-Balanced' Views of Martian Terrain

These three versions of the same image taken by the Mast Camera (Mastcam) on NASA's Mars rover Curiosity illustrate different choices that scientists can make in presenting the colors recorded by the camera. The left image is the raw, unprocessed color, as it is received directly from Mars.
The center rendering was produced after calibration of the image to show an estimate of "natural" color, or approximately what the colors would look like if we were to view the scene ourselves on Mars. The right image shows the result of then applying a processing method called white-balancing, which shows an estimate of the colors of the terrain as if illuminated under Earth-like, rather than Martian, lighting.

The image was taken by the Mastcam on Sol 19 of Curiosity's mission on Mars (Aug. 23, 2012), using only the camera's red-green-blue Bayer filters. It looks south-southwest from the rover's landing site toward Mount Sharp.


Tags: Curiosity Mars-Rover News 

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