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Sonntag, 20. Juli 2014 - 17:26 Uhr

Astronomie - Evolutionsschub durch Meteoritenregen? Kann sein

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Eine von den Hypothesen, die eine drastische Zunahme der Tier- und Pflanzenvielfalt auf der Erde in einer relativ kurzen Zeit vor 470 Mio. Jahren erklärt, hat sich bewahrheitet. Diese kleinere Zeitspanne, in der die modernen Klassen von Lebewesen entstanden sind, wird von Paläontologen als ordovizisches Aussterben bzw. ordovizische Strahlung bezeichnet. Inzwischen wurde das fehlende Verbindungsglied in der Erklärung der Ursachen jener fernen Ereignisse entdeckt, wobei ein Meteorit darauf hingewiesen hat.
Der Aerolith von ein paar Zentimetern im Querschnitt wurde in einem Tagebau bei Stockholm gefunden, wo rosa Marmor gefördert wird. Seit 20 Jahren hat man dort in Marmorflözen über hundert Meteoriten von dem gleichen Typ entdeckt. Das Alter dieser Flözen entspricht der „ordovizischen Strahlung“. Aber der neue aus dem All stammende Fund gab Anlass zum Nachdenken, da er zu einem anderen, den Forschern unbekannten Typ gehörte.
Laut der Hypothese, die übrigens von den Funden im Tagebau inspiriert wurde, stürmte vor 470 Mio. Jahren auf die Erde ein wahres Trommelfeuer an Boliden herein, das 10 Mio. Jahre dauerte. Vermutlich ging es dabei um Blöcke mit einem Durchmesser von bis zu einem Kilometer. Sie waren nicht groß genug, um globale Auswirkungen auf die Tier- und Pflanzenwelt zu haben, wie es etwa bei steinernen Ankömmlinge von 10 km der Fall gewesen wäre. Gleichzeitig veränderte das unablässige „Bombardement“ das Relief der Erde und schuf viele neue ökologische Nischen. Diese bahnten den Weg für die Artenvielfalt: In der neuen Situation mussten sich Lebewesen den wechselnden Verhältnissen anpassen. Wer damit nicht fertig wurde, starb aus.
Es wäre logisch anzunehmen, dass der Bolidenschwarm bei der Kollision von zwei größeren, sehr schnell fliegenden Himmelskörpern entstanden war, die hinsichtlich der Masse etwa mit dem Mond vergleichbar waren. Höchstwahrscheinlich geschah es zwischen den Umlaufbahnen des Mars und des Jupiter, wo unzählige größere Objekte fliegen. Theoretisch muss in einem Paar gegeneinanderprallender Körper der größere fast ganz zersplittern. Der kleinere Körper verdampft wegen der Stoßenergie, so dass von ihm nur ganz wenig Splitter übrigbleiben. Nach einer Million Jahre erreichten Staub, Steine und größere Fragmente die Erdumlaufbahn und gerieten nach und nach auf unseren Planeten.
Die Forschung hat erwiesen, dass die Natur keine zwei Asteroiden von absolut identischer Zusammensetzung kennt. Die Ähnlichkeit der früher im Tagewerk gefundenen Meteoriten zeugte davon, dass es Splitter desselben kosmischen Körpers waren. Wie ließe sich aber die interplanetare Kollision überhaupt ohne Fragmente des zweiten Himmelskörpers dieses Paares nachweisen, auf der ja die Hypothese der explosiven Evolution beruht?
Der jetzige Fund scheint der bislang einzige Überrest von ihm zu sein, über den die Forscher verfügen. Das Alter und die Dauer des freien Herumfliegens im Weltall stimmen mit denen der früheren Funde überein, während die chemische Zusammensetzung eine andere ist. Folglich hat die Kollision stattgefunden. Also bestehen kaum noch Zweifel daran, dass die explosionsartige Zunahme der Biodiversität von Asteroiden ausgelöst wurde?
Professor Alexander Markow, Leiter des Lehrstuhls für biologische Evolution der Biologischen Fakultät der Moskauer Lomonossow-Universität meint dazu:
„Sicher ist es nicht ausgeschlossen, es bedarf aber schwerwiegender Beweise. Meines Erachtens reichen die vorhandenen Argumente für die Behauptung nicht aus, gerade der Einschlag von Asteroiden wäre die zentrale Ursache der ‘ordovizischen Strahlung’. Auch gewisse innere, biologische Gründe könnten dabei eine Rolle gespielt haben.“
Laut Alexander Markow gibt es nämlich auch andere Erklärungen für die explosionsartige Evolution. Sie seien auf den Vulkanismus, die veränderte Konzentration von Kohlenstoffdioxid in der Atmosphäre und andere Faktoren zurückzuführen. Ähnlich große Evolutionssprünge haben stets einen ganzen Komplex an Ursachen, sagt weiter der Forscher.
„Man beschränkt die Vorgänge der Evolution zu Unrecht ausschließlich auf gewisse äußere Einwirkungen. Warum ist der Mensch entstanden? Weil eine Eiszeit eingetreten war. Warum sind die Dinosaurier ausgestorben? Weil ein Asteroid die Erde traf. Warum kam es zu einem stürmischen Wachstum der Artenvielfalt? Weil 10 Mio. Jahre lang Asteroiden eingeschlagen waren. Dies ist ein vereinfachtes Herangehen.“
Der prähistorische Bote hat in der Forschungsszene bereits eine Debatte ausgelöst. Wissenschaftler möchten Flözen derselben Epoche in anderen Regionen des Planeten auf Meteoritenspuren überprüfen. Ähnliche Gesteine gibt es in China, Russland, Schottland und Südamerika. Die Studie soll nicht nur auf die planetare Katastrophe, die wohl gewaltigste der letzten Milliarde Jahre, sondern auch auf die ganze Geschichte des Sonnensystems ein Schlaglicht werfen.
Quelle: abendblatt

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Sonntag, 20. Juli 2014 - 12:15 Uhr

Astronomie - RED SPRITES über Neu-Mexiko

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RED SPRITES OVER NEW MEXICO: Solar activity is extremely low (see "The All Quiet Event" below). Nevertheless, space weather continues. High above thunderstorms in the American west, red sprites are dancing across the cloudtops, reaching up to the edge of space itself. Harald Edens photographed this specimen on July 18th from the Langmuir Laboratory for Atmospheric Research in New Mexico:

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This colorful sprite occurred over a large thunderstorm system in northeast New Mexico and was visible to the naked eye. The green bands in the photograph are ionospheric gravity waves caused by the thunderstorm complex. Photograph was taken with Nikon D4s and 50 mm f/2 lens at ISO 25600.
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"This colorful sprite occurred over a large thunderstorm system in northeast New Mexico and was visible to the naked eye," says Edens. "I took the picture using a Nikon D4s and a 50 mm f/2 lens at ISO 25600."
Inhabiting the upper reaches of Earth's atmosphere alongside noctilucent clouds, meteors, and some auroras, sprites are a true space weather phenomenon. Some researchers believe they are linked to cosmic rays: subatomic particles from deep space striking the top of Earth's atmosphere produce secondary electrons that, in turn, could provide the spark that triggers sprites.
Although sprites have been seen for at least a century, most scientists did not believe they existed until after 1989 when sprites were photographed by cameras onboard the space shuttle. Now "sprite chasers" regularly photograph the upward bolts from their own homes. Give it a try!
Quelle: Spaceweather

2491 Views

Sonntag, 20. Juli 2014 - 10:51 Uhr

Raumfahrt - Astronauten testen auf ISS frei fliegende Smart SPHERES Roboter

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Three satellites fly in formation as part of the Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) investigation. This image was taken during Expedition 14 in the Destiny laboratory module.

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Inspired by science fiction, three bowling ball-size free-flying Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) have been flying inside the International Space Station since 2006. These satellites provide a test bed for development and research, each having its own power, propulsion, computer, navigation equipment, and physical and electrical connections for hardware and sensors for various experiments.
Aboard Orbital Sciences Corp.'s second contracted commercial resupply mission to the space station, which arrived to the orbital laboratory July 16,  NASA's Ames Research Center in Moffett Field, California, sent two Google prototype Project Tango smartphones that astronauts will attach to the SPHERES for technology demonstrations inside the space station. By connecting a smartphone to the SPHERES, it becomes "Smart SPHERES, " a more "intelligent" free-flying robot with built-in cameras to take pictures and video, sensors to help conduct inspections, powerful computing units to make calculations and Wi-Fi connections to transfer data in real time to the computers aboard the space station and at mission control in Houston.
For the first Smart SPHERES experiments in 2011, a Nexus S was launched to the station on the final flight of space shuttle Atlantis. For the upcoming experiments, the features of the Project Tango phone add new capabilities to increase the options of what researchers can do with the SPHERES platform.
In a two-phase experiment, astronauts will manually use the smartphones to collect visual data using the integrated custom 3-D sensor to generate a full 3-D model of their environment. After the map and its coordinate system are developed, a second activity will involve the smartphones attached to the SPHERES, becoming the free-flying Smart SPHERES. As the free-flying robots move around the space station from waypoint to waypoint, utilizing the 3-D map, they will provide situational awareness to crewmembers inside the station and flight controllers in mission control. These experiments allow NASA to test vision-based navigation in a very small mobile product. 
“NASA uses robots for research and mission operations; just think about the rovers on Mars or the robotic arm on the ISS or space shuttle," said Chris Provencher, manager of the Smart SPHERES project. "Inside the ISS space is limited, so it’s really exciting to see technology has advanced enough for us to demonstrate the use of small, mobile robots to enhance future exploration missions."
Ultimately it is the hope of researchers that these devices will perform housekeeping-type tasks, such as video surveys for safety and configuration audits, noise level measurements, air flow measurements, and air quality measurements, that will offset work the astronauts currently perform.
The SPHERES facility is managed under NASA's Human Exploration and Operations Mission Directorate, Advanced Exploration Systems division. The Smart SPHERES project and SPHERES facility are managed under the Intelligent Robotics Group at NASA Ames, with participation from NASA’s Johnson Space Center in Houston and NASA's Jet Propulsion Laboratory in Pasadena, California.
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NASA Ames' Smart SPHERES, a Synchronized Position Hold, Engage, Reorient Experimental Satellites (SPHERES) equipped with Google's Project Tango smartphone.
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Quelle: NASA

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Samstag, 19. Juli 2014 - 11:45 Uhr

UFO-Forschung - Aus dem CENAP-ARCHIV

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Cenap Report Onlinearchiv

Ab Sofort kann man die ersten 50 Ausgaben unseres ehemalig gedruckten CENAP-Report nun auch Online kostenlos einsehen und die tatsächlichen Entwicklungsprozesse bei CENAP aber auch der deutschen UFO-Szene einsehen. Vielleicht kann der eine oder ander Leser daraus ersehen WARUM unsere Position zu der UFO-Thematik immer skeptischer und zur deutschen UFo-Szene kritischer wurde. 
Finden können Sie diese auf der UFO-Information-Plattform UI:
 
Vor sechs Tagen haben wir mit Genehmigung der beiden Cenap Gründer Hansjürgen Köhler und Werner Walter das Archiv des Cenap in unsere Obhut genommen mit dem Ziel es nach und nach zu digitalisieren und allen Interessierten kostenlos auf ufo-information.de zur Verfügung zu stellen. Seitdem hat Dennis Kirstein den Scanner zum Glühen gebracht und innerhalb der letzten 5 Tage bereits die Cenap Report Ausgaben 1 bis 50 digitalisiert und online gestellt. Wir freuen uns deshalb Ihnen nach dieser kurzen Zeit bereits die ersten 50 Ausgaben aus den Jahren 1976 bis 1980 hier auf ufo-information.de präsentieren zu dürfen.
Der Cenap Report erschien in 280 gedruckten Ausgaben bis 2002 und war Deutschlands führendes Ufo-Fachmagazin mit skeptischer Ausrichtung. Das Onlinearchiv erzählt nicht nur die Geschichte des skeptischen Netzwerks Cenap, sondern ist zudem ein starkes Stück Ufo Geschichte. Alle Facetten des Ufo Mythos wurden im „CR“ besprochen und kritisch beäugt. Blicke über den deutschsprachigen Tellerrand in die internationale Ufo Szene waren dabei immer ein fester Bestandteil des Heftes. Ebenso detaillierte Ufo Fall-Analysen und aktuelle Pressemeldungen ihrer Zeit.
Wir sind davon überzeugt: Wer ein tiefen Blick in die Ufo Historie riskieren möchte, der ist mit diesem Onlinearchiv bestens bedient und findet Antworten, welche man in der gewöhnlichen Ufo Literatur nicht findet.
Zu Beginn haben wir nun die ersten 50 Ausgaben online gestellt. Dazu muss gesagt werden, dass die Qualität der Scans nur so gut sein kann, wir die originalen Druckvorlagen es nach 40 Jahren noch zuließen. Speziell die Ausgaben 1-30 lassen an manchen Stellen Schriftpassagen nur noch erahnen bzw. erst in hoher Vergrößerung leserlich werden obwohl wir alle Ausgaben mit vollen 300 dpi in Graustufen eingescannt haben. Ab Ausgabe 31 wurde eine neue Drucktechnik angewandt, was die Originale und somit unsere Scans deutlich aufwerteten.
Diese 50 Ausgaben sind erst der Anfang. In den kommenden Monaten werden wir nach und nach alle 280 Ausgaben und somit weit mehr als 10.000 Seiten hier in das Onlinearchiv integrieren. Zudem enthält das Cenap Archiv noch mehr hochinteressantes Material, welches wir auf ufo-information.de integrieren wollen. Die Arbeit daran wird Monate in Anspruch nehmen.
Der Direktlink hierzu: http://www.ufo-information.de/index.php/materialien/zeitschriften/19-beispielbeitraege/beitraege/363-cenap-report-archiv
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Begleitend hierzu können Sie auch hier auf der Raumfahrt+Astronomie-Seite von CENAP unter den CENAP-Galerien die umfangreiche Foto-Galerie unter CENAP-Timeline ansehen, welche ihnen zusätzliche Informationen zu den CENAP-Report´s geben:
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In meheren Foto-Galerien finden Sie über Hunderte UFO-Forschungs-Dokumente von den Anfängen bis Heute: http://www.hjkc.de/70.html
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Viel Spaß wünschen wir den Information-Suchenden auf den CENAP-UFO-Forschung-Spuren,
CENAP-Mannheim

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Donnerstag, 17. Juli 2014 - 07:35 Uhr

Raumfahrt - Ankunft von Orbital Commercial Resupply Services Mission (Orb-2) bei ISS

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15.07.2014

Choreographie mit dem Roboterarm der ISS

Bis auf zwölf Meter nähert sich am 16. Juli 2014 um 12.39 Uhr mitteleuropäischer Zeit das Transportfahrzeug Cygnus Orbital-2 der Internationalen Raumstation ISS - und dann muss Astronaut Alexander Gerst gemeinsam mit seinem Kollegen Steve Swanson dafür sorgen, dass der Transporter sicher eingefangen und an die Raumstation angedockt wird. Während Swanson den Roboterarm bedient, wird Gerst unter anderem die Kameras am Roboterarm steuern. Trainiert hat der deutsche ESA-Astronaut dieses Manöver bereits vor seinem Start ins All sowie in der vergangenen Woche an Bord der ISS. "Da gibt es eine ausgeklügelte Choreographie, der das Team folgt", sagt Astronautentrainer Norbert Illmer vom Deutschen Zentrum für Luft- und Raumfahrt (DLR).
"Wie eine Kobra vor ihrer Beute", beschreibt Alexander Gerst den über 17 Meter langen Roboterarm "Canadarm-2", der sich mit sieben Gelenken an der Außenseite der ISS entlangbewegen kann. Wenn der Orbiter, der am 13. Juli 2014 um 18.52 Uhr mitteleuropäischer Zeit zur ISS startete, ankommt, werden Alexander Gerst und Steve Swanson in der Aussichtskuppel Cupola bereit sein. "Alexander Gerst wird bei diesem Einfangmanöver die Assistentenrolle einnehmen und dem Operator Swanson den Rücken frei halten", sagt Astronautentrainer Illmer. Trainiert sind beide Astronauten für beide Funktionen - und könnten bei Bedarf jederzeit die Rollen tauschen.
Bevor der Roboterarm zugreifen kann, muss Gerst kontrollieren, dass sowohl die Raumstation als auch der Transporter frei und ohne Antriebsstöße schweben. Erst dann kann Swanson den Roboterarm steuern und das Raumschiff greifen. Damit er dabei die beste Sicht auf das Geschehen außerhalb der ISS hat, wird sein Assistent Alexander Gerst beispielsweise Blickwinkel und Zoom der Kameras an die  jeweilige Situation anpassen. "Swanson konzentriert sich auf die Steuerung, Alexander muss das Gesamtbild im Auge haben", erläutert Illmer. "Ohne diese Teamarbeit kann dieses Manöver nicht durchgeführt werden." 20 Minuten dauert diese "heiße" Phase, in der der Transporter mit dem Roboterarm erfasst wird. Nach einem anschließenden Check in den nächsten ein, zwei Stunden wird Cygnus Orbital-2 dann an dem amerikanischen Verbindungsknoten "Harmony" der ISS angebracht.
Ausrüstung, Experimente und Essen
Die Verbindungsluke zwischen Raumstation und Transporter wird einen Tag später geöffnet. Fast 1500 Kilogramm Fracht bringt der Transporter zur ISS mit. Dazu gehören neben einem Schwarm kleiner Satelliten, so genannten CubeSats, auch verschiedene amerikanische Studentenexperimente, Material für die Raumstation sowie Ausrüstung für Weltraumausstiege. Die  Astronauten dürften sich vor allem auf die 764,2 Kilogramm Essen, Versorgung und Crew-Pakete freuen, die ebenfalls mit Cygnus Orbital-2 ankommen. Seinen Rückflug tritt der Transporter in etwa einem Monat an, um dann gefüllt mit Abfällen über dem Südpazifik wieder in die Atmosphäre einzutreten.
Beteiligt ist der deutsche Astronaut Alexander Gerst auch bei der Ankunft des europäischen Raumtransporters ATV-5 voraussichtlich am 12. August 2014, wenn er das automatische Andocken überwachen und gegebenenfalls stoppen muss. Dann werden 6500 Kilogramm Fracht - darunter auch ein Schmelzofen (Elektromagnetische Levitator; EML) für materialwissenschaftliche Untersuchungen - die ISS erreichen.
Quelle: DLR
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Update: 17.07.2014
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Cygnus cargo ship berthed at station

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Against the backdrop of planet Earth, the International Space Station's robot arm locked onto a Cygnus cargo ship Wednesday and pulled it in for berthing to close out a near-flawless three-day rendezvous. (Credit: NASA TV)
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A Cygnus cargo ship loaded with more than 1.5 tons of supplies and equipment was plucked out of open space by the International Space Station's robot arm early Wednesday and pulled in for berthing to wrap up a three-day rendezvous.
With the cargo craft holding position about 30 feet away, Expedition 40 commander Steve Swanson, operating the Canadian-built robot arm, locked onto a grapple fixture on the bottom deck of the Orbital Sciences-built spacecraft at 6:36 a.m. EDT (GMT-4) as the two spacecraft sailed 260 miles above northern Libya.
"Houston and station, we now have a seventh crew member," Swanson radioed. "Janice Voss is now part of Expedition 40."
Voss, a five-flight shuttle veteran who worked for Orbital Sciences before joining NASA, died in 2012. The company named the Cygnus cargo ship in her honor.
"Janice devoted her life to space and accomplished many wonderful things at NASA and Orbital Sciences, including five shuttle missions," Swanson said. "And today, Janice's legacy in space continues. Welcome aboard the ISS, Janice."
Flight controllers at the Johnson Space Center in Houston then took over, operating the robot arm by remote control to slowly pull the Cygnus cargo craft in for berthing at the Earth-facing port of the forward Harmony module. Once in position, motorized bolts drove home to firmly lock the craft to the docking port.
"The mechanical systems officer here in mission control reports a good second stage capture," said NASA commentator Rob Navias. "And so at 7:53 a.m. Central time, a little over two hours after it was grappled in open space by Steve Swanson, the Expedition 40 commander, Cygnus is now hard mated to the International Space Station's Harmony module, a fixture for the station for the next four weeks."
After opening hatches between the spacecraft, the station crew will begin the process of unloading some 3,300 pounds of food, clothing, research equipment, spare parts and other gear, including 32 small "nanosat" satellites that will be released from the lab later. Twenty eight of those were provided by Planet Labs in a commercial venture to develop low-cost Earth imagery.
The grapple and berthing operation wrapped up a textbook rendezvous that began with launch of an Orbital Sciences Antares rocket Sunday from the Mid-Atlantic Regional Spaceport at NASA's Wallops Island, Va., flight facility. The Cygnus cargo craft carried out a series of carefully timed thruster firings to catch up with the station, reaching the lab complex early Wednesday and then standing by while Swanson locked on with the robot arm.
Once unloaded, the Cygnus will be packed with trash and no-longer-needed gear before unberthing on Aug. 15. After leaving the vicinity of the station, Orbital engineers plan to test new rendezvous equipment before the cargo ship re-enters the atmosphere and burns up.
The Cygnus is the first of four cargo ships expected to arrive over the next two months. A Russian Progress supply ship is scheduled for launch July 23, followed one day later by the European Space Agency's fifth and final Automated Transfer Vehicle. The ATV will arrive at the station Aug. 12. One month after that, a SpaceX Dragon cargo ship is scheduled for launch from Cape Canaveral, arriving at the station two days later.
In the midst of the cargo traffic, the station crew plans to carry out three spacewalks, with a Russian excursion by Alexander Skvortsov and Oleg Artemyev planned for Aug. 18 and two NASA EVAs on Aug. 21 and 29. Swanson and Reid Wiseman will carry out the first U.S. EVA while Wiseman and European Space Agency astronaut Alexander Gerst will carry out the second.
Swanson, Skvortsov and Artemyev plan to undock and return to Earth aboard their Soyuz TMA-12M ferry craft Sept. 11. Three fresh crew members -- Soyuz TMA-14M commander Alexander Samokutyaev, Barry Wilmore and Elena Serova -- are scheduled for launch from the Baikonur Cosmodrome in Kazakhstan on Sept. 25.
Quelle: CBS


2094 Views

Mittwoch, 16. Juli 2014 - 14:25 Uhr

Raumfahrt - Das erste Bild von der Erde entstand im Jahre 1946

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The First Ever Photograph from Space

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White Sands Missile Range—Applied Physics Laboratory
The earth as seen from a camera on V-2 rocket number 13, launched Oct. 24, 1946.
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This is the first photo ever taken from space. Shot on October 24, 1946 from a cool 65 miles up, it was taken with a 35mm camera mounted on a V-2 missile launched from the White Sands Missile Range in New Mexico.
The pre-NASA picture might look a little grainy by today’s standards — but it was, and still is, revolutionary. All earlier shots of the planet were taken from high altitude balloons. Here was a never-before seen view: our world thrown into stark relief by space.
Though, it might come as a bit of a surprise to learn that the rocket carrying the camera was a Nazi weapon. Yes, V-2s were the Nazi ballistic missiles that rained destruction on London in 1944. Rockets that were, in turn, taken from Germany by the U.S. at the end of World War II. As if that wasn’t enough, one-time Nazi scientist Wernher von Braun – who part-developed the V-2 for Germany — was involved in the ongoing development and research of the rockets with American scientists.
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Von Braun was brought to the U.S. under Operation Paperclip, a program that saw German engineers and scientists employed in America. A highly divisive figure, he eventually helped the U.S. win the space race, designing the Saturn V rocket that brought Apollo 11 to the moon.
The camera strapped to this particular rocket, though, was the work of Missile Range engineer Clyde Holliday. Holliday — who worked for the Johns Hopkins University Applied Physics Laboratory — had developed a 35mm camera that could take a photo every one and half seconds. In 1950, Halliday wrote in National Geographic that after he had strapped the camera to the rocket, the images that returned showed “how our Earth would look to visitors from another planet coming in on a space ship.”
And even though approaching aliens would surely see the world in full color, Holliday’s work persists today as a pretty awesome – if controversially sourced — precursor to the ever-famous Blue Marble.
Quelle: TIME

Tags: Raumfahrt 

2345 Views

Mittwoch, 16. Juli 2014 - 10:38 Uhr

Raumfahrt - Neue NASA Venus-Mission könnte den Höllischen Schleier des Planeten heben

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If Mars is mysterious, Venus is truly scary. Long called Earth’s twin, it’s only four months away via unmanned probe and lies more than 70 percent of Earth’s distance from the Sun.
But with surface pressures and temperatures high enough to melt lead and crush steel, why is Venus so hauntingly different from Earth? And when did it go bad?
“Venus and Earth are virtually identical twins; they’re almost the same size,” said Robert Herrick, a planetary geophysicist at the University of Alaska in Fairbanks. “But  Venus is completely uninhabitable; we really don’t understand how that dichotomy came about.”
The European Space Agency’s (ESA) Venus Express orbiter has spent the last eight years trying to dissect its hellish atmosphere and surface. But now with dwindling fuel, by year’s end the spacecraft is expected to make its final plunge into Venus’ toxic atmosphere.
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Scale representations of Venus and the Earth shown next to each other. Venus is only slightly smaller.
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While Venus Express has made scientific progress, planetary scientists say, a few major puzzles have yet to be solved.
Larry Esposito, a planetary scientist at the University of Colorado at Boulder, says the most puzzling things are: How did Venus go bad? How did the high-wind dynamics of the atmosphere arise on Venus? What is its surface made of? And does Venus still have volcanic activity?
Venus Express took infrared images of the planet’s surface and found that its biggest volcanoes do indeed indicate lava flow there within the last 250,000 years.
“Venus Express also detected a sudden increase in sulfur dioxide; the same thing that comes out of unscrubbed coal-powered plants on earth,” said Esposito. “But on Venus Express, it was interpreted as a possible real-time volcanic eruption.”
One explanation is that Venus undergoes giant volcanic eruptions every few decades. But how do these putative eruptions contribute to Venus’ ongoing dense, noxious atmosphere?
Calculations of surface-atmosphere interactions indicate that the planet’s atmospheric sulfur should be “sopped up” by the surface in a few tens of millions of years, says Kevin Baines, a planetary scientist at NASA JPL and the University of Wisconsin at Madison. Baines says this means if the present cloudy atmosphere is typical and ongoing, then there must be active volcanism to resupply the atmosphere with sulfur. He notes that “a hot atmosphere” may “soften” the surface, allowing increased sulfur emission.
One of a handful of potential Venus mission proposals — each vying for a slot in NASA’s Discovery-class mission program — could help clear up Venus’ remaining mysteries.
A proposed VASE (Venus Atmosphere and Surface Explorer) mission might skim the clouds and on a final landing even get data from the surface, says Mark Bullock, a planetary scientist at the Southwest Research Institute in Boulder, and a VASE definition team member.
But Bullock says “if you really want to understand this you have to put lots of balloons in the atmosphere to understand how the surface and the atmosphere interact.”
As for why Venus ultimately became so inhospitable?
The short answer is that as the Sun increases in luminosity, the inner edge of our solar system’s habitable zone also continually moves outward; thus, long ago, Venus simply became too hot to hold onto its liquid water.
This loss, says Baines, was likely caused by the “ravaging solar wind” and the effects of ultraviolet photons “ripping water molecules into hydrogen and oxygen,” which in turn led to the escape of Venus’ hydrogen into space.
“To me, the main puzzle is when did Venus lose its oceans,” said Bullock. “The paradigm is that Venus lost its oceans up to 600 million years after its formation. But there is absolutely no data which contradicts the possibility that Venus was actually Earth-like for billions of years.”
Could Earth suffer a similar fate?
“Earth is definitely on a path to a Venus-like condition and anthropogenic carbon emissions are the beginning of it,” said Bullock. “That’s dramatic, but there’s no question that Earth will go in that direction.”
As for finding proof of Venus’ ancient lakes or seas, Baines says a surface lander that sampled rocks and found water-bearing materials or materials that could only be formed in standing water would clinch that.
However, Bullock says there are also people who think it may not ever have had an ocean and its water was always steam.
In terms of our geological understanding of Venus, Herrick says we’re where we were with Mars three decades ago. NASA’s 1990s Magellan mission to Venus was only able to see things several football fields across and larger. But he says a newer generation of Synthetic Aperture Radars (SAR)s is capable of giving researchers much better images.
For a planet with a dense atmosphere, like Venus, Herrick says synthetic aperture radar would image the surface and researchers would interpret the black and white image results very much like images from planets with more transparent atmospheres.
A proposed RAVEN (Radar at Venus) mission would compare a new radar-imaging orbiter focused on understanding Venus’ geology as well as identifying future potential landing sites. One of its goals would be to definitively determine whether Venus has continents and whether such putative continents are composed of granitic rock, as here on Earth.
“We don’t know that the high-lying regions on Venus are actually like Earth’s continents,” said Esposito. “We haven’t identified granite yet on Venus and don’t know its major surface rock types.”
Venus doesn’t have Earth-styled plate tectonics, says Herrick, but he says we don’t have enough high-resolution topography information to understand how Venus is releasing its heat.
NASA will put out a Discovery mission Announcement of Opportunity this September. By year’s end, the agency is expected to then pick three to five proposals for further study. Conceivably, one or more of a handful of competing Venus mission proposals may ultimately be chosen and see launch as early as 2020.
As for longer range Venus missions?
“New missions that orbit the planet for decades,” said Baines, “may allow us to complete the picture of what happened to Venus to convert it from a verdant oasis to a (non)living hell.”
Quelle: Forbes

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Mittwoch, 16. Juli 2014 - 10:20 Uhr

Astronomie - NASA´s Van-Allen-Probes Entdecken Teilchenbeschleuniger im Herzen der Erde Strahlungs Gürtel

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26.07.2013

Recent observations by NASA’s twin Van Allen Probes show that particles in the radiation belts surrounding Earth are accelerated by a local kick of energy, helping to explain how these particles reach speeds of 99 percent the speed of light.
Image Credit: G. Reeves/M. Henderson
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Scientists have discovered a massive particle accelerator in the heart of one of the harshest regions of near-Earth space, a region of super-energetic, charged particles surrounding the globe called the Van Allen radiation belts. Scientists knew that something in space accelerated particles in the radiation belts to more than 99 percent the speed of light but they didn't know what that something was. New results from NASA's Van Allen Probes now show that the acceleration energy comes from within the belts themselves. Particles inside the belts are sped up by local kicks of energy, buffeting the particles to ever faster speeds, much like a perfectly timed push on a moving swing.
The discovery that the particles are accelerated by a local energy source is akin to the discovery that hurricanes grow from a local energy source, such as a region of warm ocean water. In the case of the radiation belts, the source is a region of intense electromagnetic waves, tapping energy from other particles located in the same region. Knowing the location of the acceleration will help scientists improve space weather predictions, because changes in the radiation belts can be risky for satellites near Earth. The results were published in Science magazine on July 25, 2013.
In order for scientists to understand the belts better, the Van Allen Probes were designed to fly straight through this intense area of space. When the mission launched in August 2012, it had top-level goals to understand how particles in the belts are accelerated to ultra-high energies, and how the particles can sometimes escape. By determining that this superfast acceleration comes from these local kicks of energy, as opposed to a more global process, scientists have been able to definitively answer one of those important questions for the first time.
"This is one of the most highly anticipated and exciting results from the Van Allen Probes," said David Sibeck, Van Allen Probes project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "It goes to the heart of why we launched the mission."
The radiation belts were discovered upon the launch of the very first successful U.S. satellites sent into space, Explorers I and III. It was quickly realized that the belts were some of the most hazardous environments a spacecraft can experience. Most satellite orbits are chosen to duck below the radiation belts or circle outside of them, and some satellites, such as GPS spacecraft, must operate between the two belts. When the belts swell due to incoming space weather, they can encompass these spacecraft, exposing them to dangerous radiation. Indeed, a significant number of permanent failures on spacecraft have been caused by radiation. With enough warning, we can protect technology from the worst consequences, but such warning can only be achieved if we truly understand the dynamics of what's happening inside these mysterious belts.
"Until the 1990s, we thought that the Van Allen belts were pretty well-behaved and changed slowly," said Geoff Reeves, the first author on the paper and a radiation belt scientist at Los Alamos National Laboratory in Los Alamos, N.M. "With more and more measurements, however, we realized how quickly and unpredictably the radiation belts changed. They are basically never in equilibrium, but in a constant state of change."
In fact, scientists realized that the belts don't even change consistently in response to what seem to be similar stimuli. Some solar storms caused the belts to intensify; others caused the belts to be depleted, and some seemed to have almost no effect at all. Such disparate effects from apparently similar events suggested that this region is much more mysterious than previously thought. To understand – and eventually predict – which solar storms will intensify the radiation belts, scientists want to know where the energy that accelerates the particles comes from.
The twin Van Allen Probes were designed to distinguish between two broad possibilities on what processes accelerate the particles to such amazing speeds: radial acceleration or local acceleration. In radial acceleration, particles are transported perpendicular to the magnetic fields that surround Earth, from areas of low magnetic strength far from Earth to areas of high magnetic strength nearer Earth. The laws of physics dictate that the particle speeds in this scenario will speed up when the magnetic field strength increases. So the speed would increase as the particles move toward Earth, much the way a rock rolling down hill gathers speed simply due to gravity. The local acceleration theory posits that the particles gain energy from a local energy source more similar to the way hot ocean water spawns a hurricane above it.
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Two swaths of particles surrounding Earth called the radiation belts are one of the greatest natural accelerators in the solar system, able to push particles up to 99% the speed of light. The Van Allen Probes launched in August 2012, have now discovered mechanisms behind this acceleration.
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To help distinguish between these possibilities, the Van Allen Probes consist of two spacecraft. With two sets of observations, scientists can measure the particles and energy sources in two regions of space simultaneously, which is crucial to distinguish between causes that occur locally or come from far away. Also, each spacecraft is equipped with sensors to measure particle energy and position and determine pitch angle – that is, the angle of movement with respect to Earth's magnetic fields. All of these will change in different ways depending on the forces acting on them, thus helping scientists distinguish between the theories.
Equipped with such data, Reeves and his team observed a rapid energy increase of high-energy electrons in the radiation belts on Oct. 9, 2012. If the acceleration of these electrons was occurring due to radial transport, one would measure effects starting first far from Earth and moving inward due to the very shape and strength of the surrounding fields. In such a scenario, particles moving across magnetic fields naturally jump from one to the next in a similar cascade, gathering speed and energy along the way – correlating to that scenario of rocks rolling down a hill.
But the observations didn't show an intensification that formed further away from Earth and gradually moved inward. Instead they showed an increase in energy that started right in the middle of the radiation belts and gradually spread both inward and outward, implying a local acceleration source.
"In this particular case, all of the acceleration took place in about 12 hours," said Reeves. "With previous measurements, a satellite might have only been able to fly through such an event once, and not get a chance to witness the changes actually happening. With the Van Allen Probes we have two satellites and so can observe how things change and where those changes start."
Scientists believe these new results will lead to better predictions of the complex chain of events that intensify the radiation belts to levels that can disable satellites. While the work shows that the local energy comes from electromagnetic waves coursing through the belts, it is not known exactly which such waves might be the cause. During the set of observations described in the paper, the Van Allen Probes observed a specific kind of wave called chorus waves at the same time as the particles were accelerated, but more work must be done to determine cause and effect.
"This paper helps differentiate between two broad solutions," said Sibeck. "This shows that the acceleration can happen locally. Now the scientists who study waves and magnetic fields will jump in to do their job, and find out what wave provided the push."
Luckily, such a task will also be helped along by the Van Allen Probes, which were also carefully designed to measure and distinguish between the numerous types of electromagnetic waves.
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Instruments on Van Allen Probes
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“When scientists designed the mission and the instrumentation on the probes, they looked at the scientific unknowns and said, ‘This is a great chance to unlock some fundamental knowledge about how particles are accelerated,’” said Nicola J. Fox, deputy project scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “With five identical suites of instruments on board twin spacecraft – each with a broad range of particle and field and wave detection – we have the best platform ever created to better understand this critical region of space above Earth.”
The Applied Physics Laboratory built and operates the twin Van Allen Probes for NASA’s Science Mission Directorate. The Van Allen Probes comprise the second mission in NASA's Living With a Star program, managed by Goddard, to explore aspects of the connected sun-Earth system that directly affect life and society.
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Quelle: NASA
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Update: 16.07.2014
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NASA's Van Allen Probes Show How to Accelerate Electrons
One of the great, unanswered questions for space weather scientists is just what creates two gigantic donuts of radiation surrounding Earth, called the Van Allen radiation belts. Recent data from the Van Allen Probes -- two nearly identical spacecraft that launched in 2012 -- address this question.
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The inner Van Allen radiation belt is fairly stable, but the outer one changes shape, size and composition in ways that scientists don't yet perfectly understand. Some of the particles within this belt zoom along at close to light speed, but just what accelerates these particles up to such velocities? Recent data from the Van Allen Probes suggests that it is a two-fold process: One mechanism gives the particles an initial boost and then a kind of electromagnetic wave called Whistlers does the final job to kick them up to such intense speeds.
"It is important to understand how this process happens," said Forrest Mozer, a space scientist at the University of California in Berkeley and the first author of the paper on these results that appeared online in Physical Review Letters on July 15, 2014, in conjunction with the July 18 print edition. "Not only do we think a similar process happens on the sun and around other planets, but these fast particles can damage the electronics in spacecraft and affect astronauts in space."
Over the last few decades, numerous theories about where these extremely energetic particles come from have been developed. They have largely fallen into two different possibilities. The first theory is that the particles drift in from much further out, some 400,000 miles or more, gathering energy along the way. The second theory is that some mechanism speeds up particles already inhabiting that area of space. After two years in space, the Van Allen Probes data has largely pointed to the latter.
Additionally, it has been shown that once particles attain reasonably large energies of 100 keV, they are moving at speeds in synch with giant electromagnetic waves that can speed the particles up even more – the same way a well-timed push on a swing can keep it moving higher and higher.
"This paper incorporates the Whistler waves theory previously embraced," said Shri Kanekal, the deputy mission scientist for the Van Allen Probes at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "But it provides a new explanation for how the particles get their initial push of energy."
This first mechanism is based on something called time domain structures, which Mozer and his colleagues have identified previously in the belts. They are very short duration pulses of electric field that run parallel to the magnetic fields that thread through the radiation belts. These magnetic field lines guide the movement of all the charged particles in the belts: The particles move along and gyrate around the lines as if they were tracing out the shape of a spring. During this early phase, the electric pulses push the particles faster forward in the direction parallel to the magnetic fields. This mechanism can increase the energies somewhat – though not as high as traditionally thought to be needed for the Whistler waves to have any effect. However, Mozer and his team showed, through both data from the Van Allen Probes and from simulations, that Whistlers can indeed affect particles at these lower energies.
Together the one-two punch is a mechanism that can effectively accelerate particles up to the intense speeds, which have for so long mysteriously appeared in the Van Allen belts.
"The Van Allen Probes have been able to monitor this acceleration process better than any other spacecraft because it was designed and placed in a special orbit for that purpose," said Mozer. "The mission has provided the first really strong confirmation of what's happening. This is the first time we can truly explain how the electrons are accelerated up to nearly the speed of light."
Such knowledge helps with the job of understanding the belts well enough to protect nearby spacecraft and astronauts.
The Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, built and operates the Van Allen Probes for NASA's Science Mission Directorate. The mission is the second mission in NASA's Living With a Star program, managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Quelle: NASA

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Mittwoch, 16. Juli 2014 - 09:59 Uhr

Astronomie - Rückblick auf den Jupiter / Komet Shoemaker-Levy 9 Crash vor 20 Jahren

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Comet Shoemaker-Levy 9 Fragment W Impact With Jupiter
These four images of Jupiter and the luminous night-side impact of fragment W of Comet Shoemaker-Levy 9 were taken by the Galileo spacecraft on July 22, 1994. The spacecraft was 238 million kilometers (148 million miles) from Jupiter at the time, and 621 million kilometers from Earth. The spacecraft was about 40 degrees from Earth's line of sight to Jupiter, permitting this direct view. The images were taken at intervals of 2 1/3 seconds, using the green filter (visible light). The first image, taken at an equivalent time to 8:06:10 Greenwich Mean Time (1:06 a m. Pacific Daylight Time), shows no impact. In the next three images, a point of light appears, brightens so much as to saturate its picture element, and then fades again, seven seconds after the first picture. The location is approximately 44 degrees south as predicted, dark spots to the right are from previous impacts. Jupiter is approximately 60 picture elements in diameter. Galileo tape-recorded most of its observations of the Shoemaker-Levy events during the second week of July 1994 and has since been playing the tape back selectively. Many more pictures and data from other instruments remain to be returned from the spacecraft's tape recorder. Playbacks will continue through January 1995. It is not yet certain whether the data relate to meteor bolides (the comet fragment entering Jupiter's atmosphere) or to the subsequent explosion and fireball. Once all the Galileo, Hubble Space Telescope and groundbased data are integrated, an excellent start-to-finish characterization of these remarkable phenomena will be available. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995 through 1997, is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science.
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Twenty years ago, human and robotic eyes observed the first recorded impact between cosmic bodies in the solar system, as fragments of comet Shoemaker-Levy 9 slammed into the atmosphere of Jupiter. Between July 16 and July 22, 1994, space- and Earth-based assets managed by NASA's Jet Propulsion Laboratory in Pasadena, California, joined an armada of other NASA and international telescopes, straining to get a glimpse of the historic event:
- NASA's Galileo spacecraft, still a year-and-a-half out from its arrival at Jupiter, had a unique view of fireballs that erupted from Jupiter's southern hemisphere as the comet fragments struck.
- NASA's Hubble Space Telescope, using the JPL-developed and -built Wide Field and Planetary Camera 2, observed the comet and the impact scars it left on Jupiter.
- The giant radio telescopes of NASA's Deep Space Network -- which perform radio and radar astronomy research in addition to their communications functions -- were tasked with observing radio emissions from Jupiter's radiation belt, looking for disturbances caused by comet dust.
- NASA's Voyager 2 spacecraft, then about 3.7 billion miles (6 billion kilometers) from Jupiter, observed the impacts with its ultraviolet spectrometer and a planetary radio astronomy instrument.
- The Ulysses spacecraft also made observations during the comet impact from about 500 million miles (800 million kilometers) away. Ulysses observed radio transmissions from Jupiter with its combined radio wave and plasma wave instrument.
The work of scientists in studying the Shoemaker-Levy 9 impact raised awareness about the potential for asteroid impacts on Earth and the need for predicting them ahead of time, important factors in the formation of NASA's Near-Earth Object Program Office. The NEO Program Office coordinates NASA-sponsored efforts to detect, track and characterize potentially hazardous asteroids and comets that could approach Earth.
The Galileo mission was managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for the agency's Science Mission Directorate. JPL also manages the Voyager mission and the Deep Space Network for NASA. NASA's Near-Earth Object Program at NASA Headquarters, Washington, manages and funds the search, study and monitoring of asteroids and comets whose orbits periodically bring them close to Earth. JPL manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology, Pasadena.
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The freight train of Shoemaker-Levy 9 fragments before they crashed into Jupiter.
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Comet Shoemaker-Levy 9 was captured by the gravity of Jupiter, torn apart and then crashed into the giant planet in July 1994.
When the comet was discovered in 1993, it already had been torn into more than 20 pieces traveling around the planet in a two year orbit. Further observations revealed the comet (believed to be a single body at the time) had made a close approach to Jupiter in July 1992 and was torn apart by tidal forces resulting from planet's powerful gravity. The comet was thought to have been orbiting Jupiter for about a decade before its demise.
The disruption of a comet into multiple fragments was rare and observing a captured comet in orbit about Jupiter was even more unusual, but the biggest and rarest revelation was that the fragments were going to smash into Jupiter.
NASA had spacecraft in position to watch - for the first time in history - a collision between two bodies in the solar system.
NASA's Galileo orbiter (then still en route to Jupiter) captured unprecedented direct views as the string of fragments labeled A through W smashed into Jupiter's cloud tops. The impacts started on 16 July 1994 and ended on 22 July 1994.
Many Earth-based observatories and orbiting spacecraft including Hubble Space Telescope, Ulysses and Voyager 2 also studied the impact and its aftermath.
The "freight train" of fragments smashed into Jupiter with the force of 300 million atomic bombs. The fragments created huge plumes that were 2,000 to 3,000 kilometers (1,200 to 1,900 miles) high, and heated the atmosphere to temperatures as hot as 30,000 to 40,000 degrees Celsius (53,000 to 71,000 degrees Fahrenheit). Shoemaker-Levy 9 left dark, ringed scars that were eventually erased by Jupiter's winds.
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Comet Fragment Slams into Jupiter 
Date: 17 Jul 1994
In July 1994, 21 chunks of comet Shoemaker-Levy 9, which had broken apart a year earlier, slammed into Jupiter. The Hubble telescope recorded this spectacular event.
These images, beginning at lower right, chronicle the results of one such collision. Hubble began snapping pictures of the impact area just five minutes after the collision. Nothing can be seen. Less than two hours later, a plume of dark debris is visible [bull's-eye pattern, image second from bottom]. Two impact sites are visible in the next picture, taken a few days later. The final snapshot shows three impact sites, the newest near the bull's-eye-shaped region.
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While the impact was dramatic, it was more than a show. It gave scientists an opportunity to gain new insights into Jupiter, Shoemaker-Levy 9 and cosmic collisions in general. Researchers were able to deduce the composition and structure of the comet. The collision also left dust floating on the top of Jupiter's clouds. By watching the dust spread across the planet, scientists were able to track high-altitude winds on Jupiter for the first time. And by comparing changes in the magnetosphere with changes in the atmosphere following the impact, scientists were able to study the relation-ship between them.
Scientists have calculated that the comet was originally about 1.5 to 2 kilometers (0.9 to 1.2 miles) wide. If a similar-sized object were to hit Earth, it would be devastating. The impact might send dust and debris into the sky, creating a haze that would cool the atmosphere and absorb sunlight, enveloping the entire planet in darkness. If the haze lasted long enough, plant life would die - along with the people and animals that depend on it to survive.
These kinds of collisions were more frequent in the early solar system. In fact, comet impacts were probably the main way that elements other than hydrogen and helium got to Jupiter.
Today, impacts of this size probably occur only every few centuries - and pose a real threat.
Discovery
Shoemaker-Levy 9 was discovered by Carolyn and Gene Shoemaker and David Levy in a photograph taken on 18 March 1993 with the 0.4-meter Schmidt telescope at Mt. Palomar.
How Shoemaker-Levy 9 Got Its Name
The comet was named for its discoverers. Comet Shoemaker-Levy 9 was the ninth short-periodic comet discovered by Eugene and Carolyn Shoemaker and David Levy.
Quelle: NASA

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Mittwoch, 16. Juli 2014 - 09:12 Uhr

Mars-Chroniken - Curiosity findet großen Eisen-Meteorit auf dem Mars

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On Curiosity’s 640th day (or sol) on Mars, as it continued its long drive to the base of Aeolis Mons (a.k.a. Mount Sharp), the robot stumbled across a fairly hefty meteorite. Shown here, the 2-meter-wide iron space rock can be seen embedded in the ruddy regolith.
The May 25 find adds to the puzzling reasons as to why the majority of meteorites found on the Martian surface are iron rich. On Earth, though fairly common, iron-rich meteorites are outnumbered by stony ones, leading scientists to believe that large iron-rich specimens may be more resistant to Martian erosion processes than stony space rocks.
This large meteorite appears to consist of two separate components dubbed “Lebanon” (the larger meteorite) and “Lebanon B” (the smaller one in the foreground) by Curiosity’s mission scientists.
Curiosity spent some time photographing and analyzing the meteorite with its Remote Micro-Imager (RMI), a component of the mission’s Chemistry and Camera (ChemCam) instrument. The RMI images are the circular inserts in the image above. The rover’s Mastcam instrument also imaged the area, adding color and context to the observation.Like other iron meteorites observed by Curiosity, and NASA’s Mars Exploration Rovers Opportunity and Spirit, this example is riddled with pockmarks and cavities. According to a NASA news release, these features may be caused by “preferential erosion along crystalline boundaries within the metal of the rock.” It’s also possible that the cavities used to contain olivine crystals — often found in a rare type of stony-iron meteorites called pallasites. The olivine would have long since eroded away, leaving the iron behind.
Quelle: D-News

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