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Sonntag, 9. März 2014 - 18:25 Uhr

Raumfahrt - 80. Geburtstag von Juri Gagarin, erster Mensch im Weltraum

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On March 9, legendary Soviet cosmonaut Yury Gagarin, the first man in space, would have turned 80. His 108-minute epic orbital flight on April 12, 1961 ushered in the era of space exploration – and his charming smile became its symbol.

Blasting into space aboard Soviet rocket Vostok One, Gagarin also blasted into the history of mankind. He returned to Earth as an international hero, proving that a human can indeed fly to the stars.

One of the most famous people on the planet, he remains a much loved and respected figure in Russia. For many, Gagarin is the symbol and pride of the Soviet epoch; the epoch that was not all about the Cold War, Communist ideology, and the Iron Curtain, but also about scientific, engineering, and technical progress and achievements – something that some Soviet-born people still feel nostalgic for in the new era, where market and money rule the game.

Yury Gagarin was born into a poor family on a collective farm on March 9, 1934 in the village of Klushino, near Gzhatsk (now called Gagarin in his honor) in the Smolensk region. In 1941, just as Yury entered secondary school, the village was occupied by Nazi forces who shipped his elder brother and sister to labor camps in Germany.

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After WWII, Yury and his family moved to Gzhatsk, where he continued his studies which had been disrupted by the Nazi occupation. The town seemed too small for him, and Gagarin – always active and goal-oriented – wanted to move further.

In 1949, Gagarin entered a vocational school in Lyubertsy, near Moscow, where he earned a diploma in mold-making and foundry work. In 1951, he enrolled at Saratov Industrial Technical School and joined a local aviation club – a step that defined his future choice of career and changed his life forever.

Starting from the 1930s, all boys raved about aviation,” Gagarin’s daughter Elena said in an earlier interview with RT. “Soviet pilots set numerous records, and, of course, during the war, Soviet pilots were a force that could withstand all the hardships that fell on this country’s fate. Besides, planes and helicopters were the most advanced technology at that time. That is why everybody who wanted to serve in the army and test new hardware wanted to be pilots.”

Yury Gagarin had dreamed of flying since childhood and “did everything within his power to make his dream come true,” his daughter said.

In 1955, the future first human in space was called up for military service and sent to study at an aviation school in Orenburg.

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Yury Gagarin (center) with his daughters Lena (left) and Galya (right).(RIA Novosti / Alexander Mokletsov)

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Gagarin was rather short – only 165 cm (according to some sources 157 cm) – which made it difficult for him to see the runway through the cockpit window during plane landing. One of his instructors at the aviation school, Yadkbar Akbulatov, recalled that Gagarin solved the problem by placing a cushion under his seat.

But Gagarin’s height was no obstacle to becoming a great basketball player. Also, it was largely thanks to his small size that he was later selected to become a cosmonaut, as the cockpit of the projected spaceship was rather tiny.

In 1957, already a qualified fighter pilot, Gagarin decided to serve with a Northern Fleet aviation unit in the Arctic. The same year, he married Valentina Goryacheva, with whom he had two daughters: Elena (born in 1959) and Galina (born in 1961).

“He chose, perhaps, the hardest of all possible jobs: he worked in the conditions of the far north in the Murmansk region,” his daughter Elena said. “Gagarin served there pretty long, despite the fact that he had been offered the position of a flight instructor upon his graduation from the Orenburg military school.”

On December 9, 1959, Gagarin applied to join a squad of candidates who would become cosmonauts. A week later, he was invited to Moscow for medical tests.

When Gagarin heard that they were selecting people for a squad that would test much more modern and upgraded hardware, absolutely new vehicles, he was one of those who applied and began undergoing a medical checkup,” his daughter said.

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Sporty and healthy, he passed the rigorous medical examination and was declared suitable for space missions. On March 3, 1960, Gagarin was included in the group of 20 prospective cosmonauts and on March 25, he began his training.

Yury Gagarin looked like everyone else; all the men arrived of approximately the same age and weight. And the reason was obvious: the spacecraft was designed for an average-sized man,” recalled Ada Kotovskaya, once Gagarin’s personal physician, who monitored the health of the future cosmonauts.

Speaking earlier to RT, she said the young men did not know what they had to face because the work was extremely classified. They were only told they were about to test the new craft – but they were completely unaware what kind of craft it was.

The eventual choices for the first launch were Gagarin and Gherman Titov. But on April 10, an official commission picked Gagarin for the flight, appointing Titov as his backup.

On April 12, 1961, Gagarin began the first person to orbit Earth. Seconds after the launch, he yelled his famous “Poyekhali!” (Let’s go!), piloting humanity to new discoveries and the Soviet Union to its victory over the US in the race to get the first man into space.

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On April 8, 1961, it was finally decided that Gagarin would be the first man to fly to space. Photo: 1961. Sergei Korolyov, a Member of the Soviet Academy of Sciences and Chief Designer of Rockets and Spacecraft, and Pilot-Cosmonaut of the USSR Yury Gagarin shortly before launch.

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Yury Gagarin lifted off in the early morning of April 12, 1961. At that time, only the Soviet leaders and those who had prepared the orbital flight knew about his trailblazing space journey.
Photo: April 12, 1961. Yury Gagarin and his backup man, German Titov, heading for the Baikonur Space Center.

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April 12, 1961. Yury Gagarin after landing in the Saratov Region.

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There were many myths surrounding the decision to choose Gagarin as the first cosmonaut, including his famous smile and background.

A Baikonur legend says that he was preferred over his substitute Titov because of his good manners: when he entered the spaceship training module, he took off his shoes. For Sergey Korolev, the chief space designer and the mastermind behind the first-ever manned space flight, this was, allegedly, a sign of respect and determination. There was apparently a combination of things that contributed to the choice, including Gagarin’s excellent performance during the training, his charisma, and, of course, luck.

Gagarin’s flight lasted only 108 minutes, and he was never allowed to fly into space again – something he dreamt of most of all.

He really wanted to continue flying, and he was very jealous of his fellow spacemen who got to spend much more time out in space,” his daughter Elena recalled. “He was very interested in space missions. He dreamed of mastering the new equipment; he wanted to participate in the lunar program. And in Korolev's time, they started developing the Martian program, so he believed that he would definitely participate in it, too.”

On March 27, 1968, while on a routine training flight, Gagarin was killed in a MiG-15UTI crash near the town of Kirzhach. The death of the 34-year-old cosmonaut became a nationwide tragedy, with tens of thousands of people attending his funeral. Gagarin was laid to rest in the wall of the Moscow Kremlin on Red Square.

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Funeral of the Heroes of the Soviet Union, pilot-cosmonaut Yury Gagarin and colonel-engineer Vladimir Seregin. Funeral meeting on Red Square.(RIA Novosti / Lev Ivanov)

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The 108-minute space flight changed Yury Gagarin’s life forever. The former pilot of an Air Force fighter regiment became the most famous person in the world overnight.

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Yury Gagarin became famous all over the world. Less than a month after his space flight, Gagarin traveled abroad for the first time. The first man in space went on a so-called Peace Mission, visiting Czechoslovakia, Finland, the United Kingdom, Bulgaria and Egypt.

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Quelle: RIA NOVOSTI


Tags: first man in space 

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Sonntag, 9. März 2014 - 16:00 Uhr

Raumfahrt - Kibo Kommandant: Koichi Wakata ist erster japanischer ISS-Raumstation Kommandant

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Expedition 39 commander Koichi Wakata poses between Mikhail Tyurin and Rick Mastracchio inside Japan's Kibo lab onboard the International Space Station on Feb. 22, 2014. (NASA)

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The International Space Station has its first Japanese commander.

Astronaut Koichi Wakata of JAXA (the Japan Aerospace Exploration Agency) was handed over command during a ceremony held onboard the outpost early Sunday morning (March 9). Wakata, who has been a flight engineer aboard the space station since November, will lead the complex's 39th expedition crew through mid-May.

"I am humbled to assume command of the space station," Wakata said, floating with his crewmates in the Japanese Kibo laboratory. "I am very proud as a Japanese to be be given this important commandership of ISS."

"Welcome Wakata-san," radioed JAXA mission control in Tsukuba, Japan. "It is indeed a special day for the human space program, especially for the people in Japan."

Wakata is replacing ISS Expedition 38 commander Oleg Kotov, a Russian cosmonaut who after 166 days in orbit is returning to Earth with cosmonaut Sergey Ryazanskiy and NASA astronaut Mike Hopkins on Monday. The departure of their Soyuz TMA-10M spacecraft at just after 8:00 p.m. EDT (0000 GMT on March 10), will signal the beginning of Expedition 39.

"I am really glad to pass command of the space station to my friend, JAXA astronaut Koichi Wakata," Kotov said as part of the handover ceremony. "So, now it is time to learn Japanese language aboard the station, so arigato!"

Wakata's initial charge are his two Soyuz TMA-11M crew-mates, Rick Mastracchio with NASA and Mikhail Tyurin of Roscosmos. The Soyuz TMA-13M crew, including NASA astronaut Steve Swanson and Russian cosmonauts Oleg Artemyev and Alexander Skvortsov, are scheduled to lift off to the station March 25 to complete the Expedition 39 crew.

Wakata, now 50, was selected for Japan's astronaut corps in 1992 and four years later became the nation's third full-time astronaut to fly in space.

Over the course of his three prior spaceflights, Wakata set records as Japan's first space shuttle mission specialist, his country's first astronaut to work on building the space station, and the first Japanese crewmember to complete a long-duration stay on the outpost. To date, he has logged more than 280 days off the planet.

Wakata is the first-ever Japanese astronaut to command a space mission.

"It means a lot to Japan to have its own representative to command the International Space Station," Wakata said in a briefing. "It's a big milestone for Japanese human space exploration to have this experience."

Though Japan does not launch its own crewmembers, it is a well represented partner aboard the space station.

"Since Japan has been involved in the International Space Station program, we have worked hard," Wakata said in a NASA interview. "JAXA launched the Japanese logistics module, an experiment module, the Kibo module."

The Kibo lab, one of three science-dedicated modules that are attached to the space station, is the complex's largest room. It is outfitted with its own experiment airlock, robotic arm and platform (porch) for exterior science experiments.

JAXA also launches cargo the space station using its H-II Transfer Vehicles (HTV), known as "Kounotori," or "white stork." To date, Japan has launched four of the unmanned resupply craft, with a fifth due to launch this summer.

"Looking at the Kibo's performance and [HTV] Kounotori's contribution, Japan has become a very reliable partner of the International Space Station program," Wakata said.

For the more than 13 years the station has been crewed, most of its commanders have either been U.S. astronauts or Russian cosmonauts. Sixteen NASA astronauts and 14 Roscosmos cosmonauts have headed expedition crews, though Russia has had two crewmen serve as commander twice, and one who has led four station increments.

In 2009, European Space Agency (ESA) astronaut Frank De Winne became the first non-American, non-Russian to lead serve as space station commander. Since then, only one other nation's astronaut has led the outpost, Canada's Chris Hadfield in 2013.

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Quelle; SC

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Wakata to become 33rd commander of ISS on Sunday

Astronaut Koichi Wakata, now serving his second long-term assignment on the International Space Station, was set to become the first Japanese commander of the ISS on Sunday evening, Japan time.

Wakata, 50, will take on the heavy responsibility of being the 33rd ISS commander for a term of about two months until mid-May.

Eight Japanese astronauts have been sent into outer space since Mamoru Mori boarded the space shuttle Endeavour as the first Japanese astronaut in 1992. Wakata’s assumption of the ISS command is the latest milestone in the nation’s manned space development program.

The ISS commander’s roles include serving as the representative of the space station, such as by communicating with the U.S. National Aeronautics and Space Administration and dignitaries from various countries as a moderator. The commander also must ensure the safety of the crew in emergencies such as fire or the high-speed approach of space debris, giving proper instructions.

The commander is replaced at intervals of several months to half a year, when ISS crew members return to Earth.

Wakata, who has been aboard the ISS since November on a six-month mission, will take over the command from Russian Oleg Kotov, 48, who will return to Earth on Tuesday.

Wakata said in a communication with Earth that he would like to reinforce good relationships with the five other ISS astronauts to help them improve their abilities.

ISS commanders are selected at a conference of the space agencies of Japan, Canada, Europe, Russia and the United States, which have been participating in the ISS project.

The United States, in particular, has a great influence on the selection, as the country plays a central part in the project.

Yoshiyuki Hasegawa, an executive director of the Japan Aerospace Exploration Agency, said the United States confidentially consulted JAXA in the early 2000s about choosing Wakata as a future ISS commander. It was around the time Wakata received a high evaluation of his technical skills for work on assembling the ISS and other operations.

Wakata was officially chosen as the ISS commander for the 39th expedition mission during a 2011 meeting of the space agencies of the member countries. His experience as an administrator who coordinated the schedules of the astronauts was also said to be highly regarded.

Since the time when JAXA was called the National Space Development Agency, it has been sending astronauts and other personnel to NASA to train and learn administrative management methods. Wakata—now on his fourth stay in space, the most ever by a Japanese astronaut—has been the driving force behind these efforts.

“His appointment as the ISS commander proves that Japan was finally recognized as a partner on an equal footing [with other participants],” said Mori, 66, currently the chief executive director of the National Museum of Emerging Science and Innovation (Miraikan).

Quelle: TheJapanNews

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Astronaut Wakata's Assumption of the ISS Commander

March 9, 2014 (JST)

Japan Aerospace Exploration Agency (JAXA)

Astronaut Wakata Koichi, who is in his long-duration stay on board the ISS, has succeeded Russian cosmonaut Oleg Kotov and become the 39th ISS Commander on March 9, 2014.

Wakata will take the leadership of the six ISS crewmembers until the day before he leaves the ISS on Soyuz spacecraft (37S/TMA-11M) scheduled around mid-May.

Astronaut Wakata Koichi's Assumption of the ISS Commander


It is my great pleasure that Astronaut Wakata Koichi, who is in his long-duration stay on board the ISS, has succeeded Russian cosmonaut Oleg Kotov and become the 39th ISS Commander on March 9, 2014.

The ISS Commander must take the great responsibility and high capability of crisis management for ensuring the crewmember's safety and the success of the ISS missions. I believe that Wakata's assumption of the ISS Commander results from his versatile skills and leadership he has performed through the ground training and the on-orbit experiences, and also from the trust the international society place in Japan which Japan has built in the course of the space development.

Wakata has "Wa" as his principle word of this long-duration stay. The word, meaning Japanese spirit of harmony, is one of the virtues that Japanese praise most. The ISS is a symbol of fifteen nations' international cooperation. I am certain that the Japanese will be in empathy with Wakata fulfilling his duty as the ISS Commander with the heart of "Wa".

On March 11, three years will have passed since Japan suffered from the tremendous damage caused by the Great East Japan Earthquake. I hope that Wakata's unremitting challenge encourages the Japanese in reconstructing from the disaster, following the Olympic athletes who have showed us brilliant performances in Sochi.

I would like to express my deepest gratitude to the National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency (FSA), all other domestic and overseas organizations, and the individuals for their efforts and support. I appreciate your continuous cooperation with us.

Thank you,

March 9, 2014
Naoki Okumura
President
Japan Aerospace Exploration Agency (JAXA)
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Dear Mr. Miyake:

On March 9, 2014 for the first time in history, a Japanese astronaut, Dr. Koichi Wakata, will assume command of the International Space Station (ISS). On this very memorable occasion, I congratulate JAXA and the nation of Japan on this milestone in human space flight. It is a testament to the critical contributions by Japan to the ISS partnership and the strong ties amongst the 15 partner nations.

JAXA has developed a world-class orbiting laboratory, Kibo, and is conducting groundbreaking research. I am confident the research being conducted aboard the ISS will yield benefits for all humankind and the strong ties between our nations will help lead humanity in the exploration of space.

Sincerely,



Michael T. Suffredini
Manager, International Space Station Program
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Dear Dr. Miyake,

Please accept my sincere congratulations on the occasion of a successful conclusion of the thirty eighth long duration expedition of the International Space Station (ISS) and the beginning of work of the thirty ninth long duration expedition (ISS-39) on ISS.
For the first time on ISS the JAXA astronaut Mr. Koichi Wakata started fulfillment of duties as commander of station in expedition ISS-39 that is an important milestone on a way of expansion of partnership in the field of construction and operation of the ISS. This stage opens additional opportunities for implementation of the scientific program researches, including our joint experiments.
I wish optimism look at prospects of implementation of new joint projects and deepening of our cooperation.

Sincerely,



A.B.Krasnov
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Quelle: JAXA

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Sonntag, 9. März 2014 - 10:36 Uhr

Astronomie - Gebadet in hochroten Licht: Neu entdeckte Exoplaneten und der Aussicht auf Bewohnbarkeit um Rote Zwerg Sterne

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The possibility of life and intelligence appearing very early in the history of the Universe has been pondered in many science fiction stories, from Arthur C. Clarke’s “Odyssey” book series to “Star Trek” and “Babylon 5″ on television. Though speculative, this idea has been given more credence in recent years, with the discovery of many exoplanets around the long-lived red dwarf stars that permeate the galaxy and from a series of studies suggesting that the conditions on at least some of these planets could allow for the emergence and development of life.

Red dwarfs, officially known as M-class stars, are considered to be the most abundant stellar population in the Milky Way galaxy. Astrophysicists have calculated that red dwarfs generally account for approximately 90 percent of the stars inside elliptical galaxies and 70 to 80 percent of those inside spiral galaxies like our own. Cooler, dimmer, and less massive than G-type yellow dwarf stars like the Sun, red dwarfs burn their nuclear fuel at a much slower rate, which allows them to live for hundreds of billions to even trillions of years.

Historically, red dwarfs were generally neglected by astrobiologists in their search for life elsewhere in the Universe. Conventional wisdom held that conditions near these stars would make the emergence of life very unlikely on any planets orbiting around them. With surface temperatures ranging between 2,500 to 4,000 K and luminosities between 1/10,000th to 10 percent that of the Sun, red dwarfs were considered too dim for harboring any habitable planets. Furthermore, the habitable zones around red dwarfs lie very close to these stars. Any possible planets orbiting these stars would probably end up being tidally locked, with one hemisphere constantly facing the star and the other constantly buried in eternal darkness. Red dwarfs themselves are also very active, especially during the first couple billion years of their lives, regularly shooting off large solar flares while bathing their surroundings with large doses of lethal ultraviolet radiation.

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A comparison of different star sizes, shown to scale. Image Credit: NASA, ESA and A. Feild (STScI)

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Yet studies in recent years have painted a picture showing that red dwarfs could be more hospitable to life than previously thought. For instance, it was argued that any possible habitable “Super Earths” (planets with masses slightly larger than Earth’s) that would possess a strong magnetosphere would brave coronal mass ejections and most of the lethal ultraviolet radiation that these stars emit. In addition, theoretical models have shown that a thick, cloudy atmosphere with a chemical composition consisting of carbon dioxide and water would be able to stabilise the temperatures in both hemispheres of a tidally locked planet, through convection and atmospheric circulation. Such were the results of a study made in 2013 by a team of scientists led by Jun Yang of the University of Chicago’s Dept. of the Geophysical Sciences, concluding that “our results demonstrate that at high stellar flux, Earth-like tidally locked planets have a high planetary albedo, a low greenhouse effect, and therefore low enough surface temperatures to be habitable.”

A new study to be published in Monthly Notices of the Royal Astronomical Society by an international team of astronomers brings red dwarfs again in the spotlight by announcing the discovery of eight new exoplanet candidates orbiting the nearby red dwarf stars GJ 27.1, GJ 160.2, GJ 180, GJ 229, GJ 422, and GJ 682, located between 15 and 80 light-years from Earth.

The team worked with data from past observations of 41 nearby red dwarfs that were conducted with two high-precision “planet-hunting” instruments at the European Southern Observatory (ESO) in Chile: the High Accuracy Radial Velocity Planet Searcher, or HARPS, and the Ultraviolet and Visual Echelle Spectrograph, or UVES, installed on ESO’s 3.6m telescope at the La Silla Observatory and the Very Large Telescope (VLT) on Cerro Paranal respectively. Both spectrographs have been very successful in the search for exoplanets, discovering many dozens of alien worlds that have made headlines in recent years, including possibly habitable ones around Gliese 581 and Gliese 667, two red dwarf stars 20 and 22 light-years away, respectively, and Alpha Centauri Bb, a planetary candidate around Alpha Centauri, the closest star system to the Sun, 4.37 light-years away.

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Conceptual art of the new planetary candidates discovered by Tuomi’s team. Image Credit: Guillem Anglada-Escudé, Queen Mary University of London

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Both instruments hunt for planets using the “radial velocity” method. Where Kepler and other space telescopes look for the dimming of a star’s light caused by the passage of a planet across the star’s face, HARPS and UVES look for the gentle “wobble” in a star’s motion, caused by the gravitational tug of the planets orbiting around it. This wobbling motion is reflected in the star’s spectrum, with specific spectral lines displaying constant, periodic displacements, or Doppler shifts, due to the star’s periodic movement toward and away from us. As an exoplanet detection technique, radial velocity has been the most widely used and is most useful when searching for planets that lie really close to their host stars. This makes it ideal for the discovery of possible habitable planets around red dwarfs as well.

Although both spectrographs separately detected signs for the existence of planetary candidates around the stars examined in the recent study, the signals weren’t clear enough to stand out from the random noise in the data. The team of astronomers used a Bayesian statistical analysis for both the HARPS and UVES data, with which they were able to detect the exoplanet signatures. “We were looking at the data from UVES alone, and noticed some variability that could not be explained by random noise,” says Mikko Tuomi an astronomer at the University of Hertfordshire, U.K., and lead author of the study. “By combining those with data from HARPS, we managed to spot this spectacular haul of planet candidates.”

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Artistic representation of the habitable zone Super-Earth planets Gliese 180 b and c, and Gliese 422 b, and Gliese 682 c. Earth, Mars, Neptune, and Jupiter are shown for size comparison. Image Credit/Caption: Planetary Habitability Laboratory @ UPR Arecibo, NASA.

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The most interesting part of Tuomi’s team’s exoplanet discoveries was that most of the planet candidates were found to be “Super Earths,” with masses ranging from 4.5 to 10 times that of our planet. “Based on the analyses of the combined UVES and HARPS radial velocities of the 41 nearby M dwarfs,” writes the team in their study, “these data sets contain the signals of eight new exoplanet candidates, out of which seven can be classified as Super Earths due to their minimum masses that are higher than that of the Earth, but still lower for most candidates considerably so, than one Neptune-mass.” In addition, four of the newly discovered planets, Gliese 180b and c, Gliese 422b, and Gliese 682c, lie inside the habitable zone of their respective stars.

Based on the sample of the eight newly discovered candidates, and the presence of ten more additional planetary-like signals that couldn’t be separated from the noise in the data to be confirmed as candidates, Tuomi’s team used the same Bayesian statistical analysis method to estimate the probability and overall occurrence rate of planets around red dwarf stars in the Sun’s cosmic neighborhood. To that end, they divided planets in two plots: one for orbital periods ranging between 1 and 10,000 days, and one for mass, ranging between 3 and 100 Earth masses. The team used their statistical analysis methods to try and see the probability of occurrence for the planets in each subdivision.

The team’s results showed that every red dwarf must harbor at least one Super Earth-sized planet and that nearly 25 percent of all red dwarfs examined should harbor a habitable planet. “The resulting occurrence rates show several features that can be considered as representative of the underlying population of planets around M dwarfs,” writes the team in their study. “According to our results, M dwarfs are hosts to an abundance of low-mass planets and the occurrence rate of planets less massive than 10 Earth masses, is of the order of one planet per star, possibly even greater. Our results also indicate that planets with masses between 3 and 10 Earth masses, are common in the stellar habitable zones of M dwarfs, with an estimated occurrence rate of 0.21 planets per star.”

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These images show the star fields around the new three stellar systems with four potentially habitable planet candidates discovered by astronomers led by Mikko Tuomi from the University of Hertfordshire. The field of view is about the size of the full Moon. A small telescope is necessary to see these since they are dim red dwarf stars. Image Credit/Caption: Planetary Habitability Laboratory @ UPR Arecibo, CDS/Aladin

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The study comes to verify previous similar ones that were based on data from NASA’s Kepler space telescope, which have shown that almost every Sun-like star should harbor planets as well, with one-fourth of them being potentially habitable. Furthermore, the work done by Tuomi’s team showcases the importance of extending the search for habitability in places and environments that were once thought to be too hostile for life, like those around red dwarf stars: “M dwarfs are the most abundant type of stars in the Solar neighbourhood. Therefore, the occurrence rate of planets around these stars will dominate any general estimates of the occurrence rate of planets.”

Recent theoretical work by the scientific community shows that this paradigm shift in our definition of habitable environments is slowly taking place. In their search for life, astrobiologists are now considering the possibility of “superhabitable“ worlds—planets that lie outside of their star’s habitable zone—as being promising candidates to harbor life. Red dwarfs could turn out to be ideal places to search for these types of worlds. With lifetimes on the order of hundreds of billions of years, these stars could nurture the development of life in these planets for timescales that would greatly exceed the entire life-cycle of the Sun.

“I have no doubt that in reality the future will be vastly more surprising than anything I can imagine. Now my own suspicion is that the Universe is not only queerer than we suppose, but queerer than we can suppose,” wrote J. B. S. Haldane in his seminal 1927 book, Possible Worlds.

If the emergence of life is a phenomenon that happens relatively early in a planet’s life, as it has been here on Earth, then it may not be a stretch to wonder if a potentially habitable planet around an inconspicuous red dwarf, somewhere inside the vast expanses of the Milky Way, was the first cradle of life in the galaxy during a very young and early Universe.

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Quelle: AS


2627 Views

Samstag, 8. März 2014 - 11:41 Uhr

Astronomie - Mojave-Krater kann Quelle von vielen Marsmeteoriten sein

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A camera on the Mars Reconnaissance Orbiter snapped this mosaic of images of the 55-kilometer-wide Mojave Crater. The impact that created the crater may have ejected many of the Martian meteorites now found on Earth.

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Many of the rougly 150 Martian meteorites that have been found on Earth may have been launched into space during the impact that created the Mojave Crater on Mars.

The minerals in the meteorites, called shergottites, are similar to those found in the crater, and the age of the crater — which is at least 3 million years old — matches evidence of when the meteorites were ejected. But the meteorites may have crystalized as far back as 4.3 billion years ago, making them, along with the Allan Hills 84001 meteorite, among the oldest known material from Mars, scientists report March 6 in Science.

Other estimates pin the age of the rocks at less than 600 million years, but the younger appearance could be explained by melting during impact, the scientists say.

Quelle: ScienceNews


2691 Views

Samstag, 8. März 2014 - 09:35 Uhr

Astronomie - Entwicklungshilfe aus dem All - Meteorit von Tscheljabinsk hat Nanokristalle

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Tscheljabinsk-Meteorit kann Entwicklung von Nanotechnologien begünstigen

Dmitri Pawlow, Leiter des Lehrstuhls für Halbleiter und Optotronik an der Lobatschewski-Universität Nischni Nowgorod, berichtet Folgendes:

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„Wir haben entdeckt, dass sich Nanokristalle im Meteorit von Tscheljabinsk herausbilden. Diese Partikel haben eine Kristallstruktur und sind einen Nanometer groß. Zuvor wurde bei Meteoriten nie so etwas festgestellt. Bei Nanotechnologien versucht man, solche Objekte künstlich zu erzeugen, und dieses Objekt ist nun aus dem Weltraum gekommen. Die Ursache für die Entstehung dieser Nanokristalle ist allerdings unklar.“

Die im Meteorit enthaltenen Nanokristalle bestehen aus einem Mineral, der aus Magnesium, Eisen und Sauerstoff zusammengesetzt ist. Auf der Erde entsteht er nur in den Oberschichten des Erdmantels bei extrem hohem Druck und Temperatur. Mehr noch: Die entdeckten Nanokristalle haben eine ideale sphärische Form. Das zeugt davon, dass der Himmelskörper einst extrem hohen Temperaturen und Druck ausgesetzt war. Daher seien die Nanokristall-Partikel möglicherweise erst dann entstanden, als der Meteorit mit hoher Geschwindigkeit in Richtung Erde raste, erläutert Dmitri Pawlow.

„Als der Himmelskörper unterwegs war, erhitzte er sich enorm. Die Temperatur konnte wohl bei mehreren tausend Grad liegen. Zudem kam es in einer Höhe von mehr als 15 Kilometern zu dessen Explosion. Die nach der Explosion geformten Bruchstücke fielen dann auf die Erde. Einer dieser kleinen Bruchstücke wurde zu uns nach Tscheljabinsk zugeliefert. Objekte mit Nanokristall-Partikel sind auf jeden Fall in Bezug auf ihre physikalischen Eigenschaften sehr interessant, denn sie entstehen aus der Quantennatur kleiner Einschlüsse. Dort ändert sich nämlich das Energiespektrum des Festkörpers.“

Festgestellt werden konnte auch, dass die Nanokristalle des Meteorites lumineszenzfähig sind. Sie strahlen sichtbares und infrarotes Licht im Wellenbereich zwischen 675 und 800 Nanometern ab. Diese Entdeckung kann die Entwicklung von Systemen mit optisch aktiven Medien fördern. Dmitri Pawlow setzt fort:

„Systeme mit optisch aktiven Medien werden schon seit langem in der Optotronik entwickelt und verwendet. Doch die Technologien zu deren Erzeugung werden stets verbessert. Nun hat die Natur selbst auf eine weitere Möglichkeit zu deren Erzeugung hingewiesen.“

Heutzutage versuchen Wissenschaftler weltweit, Nanokristalle aus Halbleitern künstlich zu erzeugen. Der Schlüssel zu diesem Rätsel steckt wahrscheinlich im Meteorit von Tscheljabinsk, schlussfolgert Dmitri Pawlow.

Quelle: 02elf-Abendblatt


2545 Views

Freitag, 7. März 2014 - 17:59 Uhr

Astronomie - Erfolgreiche 5 Jahre-Statistik bei Kepler´s Planetensuche

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The panel features an image of Kepler's launch and artist concepts of milestone discoveries (l to r): Kepler-9b and c, Kepler-10b, Kepler-11, Kepler-16b, Kepler-22 and Kepler-64f. The final panel illustrates exoplanet discoveries: blue is previous; red is previous Kepler; gold is Kepler's on Feb. 26

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Five years ago today, on March 6, 2009, NASA's Kepler Space Telescope rocketed into the night skies above Cape Canaveral Air Force Station in Florida to find planets around other stars, called exoplanets, in search of potentially habitable worlds.

Since then, Kepler has unveiled a whole new side of our galaxy -- one that is teeming with planets. Because of Kepler we now know that most stars have planets, Earth-sized planets are common, and planets quite unlike those in our solar system exist.

By analyzing Kepler data, scientists have identified more than 3,600 candidates believed to be planets, and verified that 961 of those candidates actually are planets, many as small as Earth. Discoveries made using Kepler now account for more than half of all the known exoplanets.

"During the last five years, Kepler has produced results needed to take the next big step forward in humankind's search for life in our galaxy— providing information needed for future missions that will ultimately determine the atmospheric composition of Earth-sized exoplanets to discover if they could be habitable," said William Borucki, Kepler principal investigator at NASA's Ames Research Center in Moffett Field, Calif.

Kepler's finds include planets that orbit in the habitable zone, the range of distances from a star where the surface temperature of an orbiting planet may be suitable for life-giving liquid water. One example of a habitable zone planet found by the mission is known as Kepler-22b. At 2.4 times the size of Earth, it is thought to be too big to be rocky and support life. Scientists believe other habitable zone planets found by the Kepler mission might be rocky, such as Kepler-62f, which is 40 percent larger in size than Earth.

A twin to Earth -- a planet with the same temperature and size as Earth -- has not yet been identified, but the analysis is far from over as scientists continue to search the Kepler data for the tiny signature of such a planet.

Other Kepler discoveries include hundreds of star systems hosting multiple planets, and have established a new class of planetary system where planets orbit more than one sun.

In August of last year, the mission ended its science observations after a faulty reaction wheel affected the telescope's ability to point precisely. The mission may be able to operate in a different mode, and continue to do science. This next-generation mission proposal, called K2, will be considered for funding by NASA in the 2014 Astrophysics Senior Review of Operating Missions.

Ames is responsible for the Kepler mission concept, ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed Kepler mission development. Ball Aerospace & Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder. The Space Telescope Science Institute in Baltimore archives, hosts and distributes Kepler science data. Kepler is NASA's 10th Discovery Mission and was funded by the agency's Science Mission Directorate.

Quelle: NASA


2370 Views

Freitag, 7. März 2014 - 16:00 Uhr

Raumfahrt - Galaktische Tankstellen - MIT-Team schlägt vor, zusätzliche Speicherung von Raketentreibstoff im Weltraum für zukünftige Missionen.

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Future lunar missions may be fueled by gas stations in space, according to MIT engineers: A spacecraft might dock at a propellant depot, somewhere between the Earth and the moon, and pick up extra rocket fuel before making its way to the lunar surface.

Orbiting way stations could reduce the fuel a spacecraft needs to carry from Earth — and with less fuel onboard, a rocket could launch heavier payloads, such as large scientific experiments.

Over the last few decades, scientists have proposed various designs, such as building a fuel-manufacturing station on the moon and sending tankers to refill floating depots. But most ideas have come with hefty price tags, requiring long-term investment.

The MIT team has come up with two cost-efficient depot designs that do not require such long-term commitment. Both designs take advantage of the fact that each lunar mission carries a supply of “contingency propellant” — fuel that’s meant to be used only in emergencies. In most cases, this backup fuel goes unused, and is either left on the moon or burned up as the crew re-enters the Earth’s atmosphere.

Instead, the MIT team proposes using contingency propellant from past missions to fuel future spacecraft. For instance, as a mission heads back to Earth, it may drop a tank of contingency propellant at a depot before heading home. The next mission can pick up the fuel tank on its way to the moon as its own emergency supply. If it ends up not needing the extra propellant, it can also drop it at the depot for the next mission — an arrangement that the team refers to as a “steady-state” approach.

A depot may also accumulate contingency propellant from multiple missions, part of an approach the researchers call “stockpiling.” Spacecraft heading to the moon would carry contingency propellant as they normally would, dropping the tank at a depot on the way back to Earth if it’s not needed; over time, the depot builds up a large fuel supply. This way, if a large lunar mission launches in the future, its rocket wouldn’t need a huge fuel supply to launch the heavier payload. Instead, it can stop at the depot to collect the stockpiled propellant to fuel its landing on the moon.

“Whatever rockets you use, you’d like to take full advantage of your lifting capacity,” says Jeffrey Hoffman, a professor of the practice in MIT’s Department of Aeronautics and Astronautics. “Most of what we launch from the Earth is propellant. So whatever you can save, there’s that much more payload you can take with you.”

Hoffman and his students — Koki Ho, Katherine Gerhard, Austin Nicholas, and Alexander Buck — outline their depot architecture in the journal Acta Astronautica.

Pickup and drop-off in space

The researchers came up with a basic mission strategy to return humans to the moon, one slightly different from that of the Apollo missions. During the Apollo era, spacecraft circled close to the lunar equator — a route that required little change in direction, and little fuel to stay on track. In the future, lunar missions may take a more flexible approach, with the freedom to change course to explore farther reaches of the moon — such as the polar caps, for evidence of water — a strategy that would require each spacecraft to carry extra fuel to change orbits.

Working under the assumption of a more global exploration strategy, the researchers designed a basic architecture involving a series of stand-alone missions, each exploring the surface of the moon for seven to 14 days. This mission plan requires that a spacecraft returning to Earth must change its orbital plane when needed. Under this basic scenario, missions could operate under existing infrastructure, without fuel depots, meaning that each spacecraft would carry its own supply of contingency propellant.

The researchers then drew up two depot designs to improve the efficiency of the basic scenario. In both designs, depots would be stationed at Lagrange points — regions in space between the Earth, moon, and sun that maintain gravitational equilibrium. Objects at these points remain in place, keeping the same relative position with respect to the Earth and the moon.

Hoffman says that ideally, transferring fuel between the depot and a spacecraft would simply involve astronauts or a robotic arm picking up a tank. The alternative — siphoning fuel from tank to tank like you would for your car — is a bit trickier, as liquid tends to float in a gravity-free environment. But, Hoffman says, it’s doable.

“In building the International Space Station, every time a new module is added, we’ve had to hook up new fluid connections,” Hoffman says. “It’s not a trivial design problem, but it can be done.”

‘Creating value … against political uncertainty’

The main drawbacks for both depot designs include maintenance; keeping depots within the Lagrange point; and preventing a phenomenon, called “boil-off,” in which fuel that’s not kept at cold-enough temperatures can boil away. If scientists can find ways around these challenges, Hoffman says, gas stations in space could be an efficient way to support large lunar explorations.

“One of the problems with large space programs is, you invest a huge amount in building up the infrastructure, and then a program gets canceled,” Hoffman says. “With depot architectures, you’re creating value which is robust against political uncertainty.”

The paper came out of two MIT classes taught by Hoffman: 16.851 (Satellite Engineering) and 16.89 (Space Systems Engineering), in which students also looked at redesigning a lunar lander and evaluated different approaches to landing on the moon.

James Head, a professor of geological sciences at Brown University, says the group’s two approaches optimize the possibility of both near-lunar missions and more ambitious, longer-duration missions to more distant destinations.

“Currently, NASA is once again considering circumlunar human operations and developing architectures for moving on to Mars,” Head says. “So this paper is extremely important and timely in the context of developing NASA plans for human exploration beyond low Earth orbit.”

Quelle: MIT - Massachusetts Institute of Technology


Tags: Galactic gas stations 

2624 Views

Freitag, 7. März 2014 - 10:15 Uhr

Astronomie - Kollidierende Kometen könnten Gasklumpen um Beta Pictoris erklären

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ALMA entdeckt rätselhaften Gasklumpen in der Trümmerscheibe um jungen Stern

Basierend auf Beobachtungen mit dem Atacama Large Millimeter/submillimeter Array (ALMA) im Norden Chiles haben Astronomen heute die Entdeckung eines unerwarteten Klumpens aus Kohlenstoffmonoxid-Gas in der Staubscheibe des Sterns Beta Pictoris bekanntgegeben. Das ist überraschend, denn man würde davon ausgehen, dass dieses Gas in kurzer Zeit von der Strahlung des Sterns zerstört werden sollte. Irgendetwas – wahrscheinlich häufige Zusammenstöße zwischen kleinen eishaltigen Objekten wie Kometen – muss für die kontinuierliche Wiederauffüllung des Gases verantwortlich sein. Die neuen Ergebnisse werden heute in der Fachzeitschrift Science veröffentlicht.

Das System des nahegelegenen Sterns Beta Pictoris, der leicht mit dem bloßen Auge am Südhimmel zu sehen ist, wird als archetypisches junges Planetensystem gepriesen. Man weiß, dass es einen Planeten beherbergt, der sich auf einer Umlaufbahn in 1,2 Milliarden Kilometern Entfernung vom Stern bewegt. Beta Pictoris war einer der ersten Sterne mit einer großen Scheibe aus Staubtrümmern, den man fand [1].  

Neue Beobachtungen mit ALMA haben nun gezeigt, dass die Scheibe von Kohlenstoffmonoxid-Gas durchsetzt ist. Paradoxerweise könnte die Anwesenheit von Kohlenstoffmonoxid, das für uns Menschen auf der Erde äußerst schädlich ist, ein Hinweis dafür sein, dass das Planetensystem Beta Pictoris irgendwann ein gutes Habitat für Leben sein könnte. Der Kometenbeschuss, den seine Planeten gerade durchleben, versorgt sie vermutlich mit dem Wasser, das Leben erst möglich macht [2].
 
Kohlenstoffmonoxid wird allerdings leicht und schnell von der Strahlung des Sterns gespalten – an der Stelle, an der es in der Scheibe von Beta Pictoris beobachtet wird, kann es nur etwa 100 Jahre lang existieren. Es in der 12 Millionen Jahre alten Scheibe von Beta Pictoris zu finden, war daher für die Wissenschaftler völlig überraschend. Es stellt sich daher die Frage, wo es herkommt und warum es immer noch dort ist.

„Sofern wir Beta Pictoris nicht gerade in einer besonders ungewöhnlichen Phase beobachten, muss das Kohlenstoffmonoxid kontinuierlich aufgefüllt werden“, erläutert William R.F. Dent, ESO-Astronom am Joint ALMA Office in Santiago de Chile und Erstautor des heute veröffentlichten Artikels in der Fachzeitschrift Science. „Die häufigsten Quellen für Kohlenstoffmonoxid in einem jungen Sonnensystem sind Zusammenstöße zwischen eishaltigen Objekten, die von Kometen bis hin zu größeren, planetenartigen Objekten reichen.“ 

Die Zerstörungsrate muss jedoch sehr hoch sein: „Um die beobachtete Menge an Kohlenstoffmonoxid zu erhalten, müsste die Kollisionsrate in der Tat erstaunlich hoch sein – eine große Kometenkollision alle fünf Minuten“, merkt Aki Roberge an, NASA-Astronom am Goddard Research Center in Greenbelt in den USA und Koautor des Fachartikels. „Um diese Kollisionsrate zu aufrechtzuerhalten, müsste es ein sehr dichter, massereicher Kometenschwarm sein.“ 

Aber es gab noch eine weitere Überraschung in den ALMA-Daten, mit denen das Kohlenstoffmonoxid nicht nur überhaupt erst  sichtbar gemacht werden konnte sondern gleichzeitig auch dessen Verteilung in der Scheibe kartiert werden konnte. Ermöglicht wurde dies durch ALMAs einzigartige Fähigkeit, gleichzeitig sowohl die Position als auch die Geschwindigkeit des Gases zu messen. Es ergab sich, dass das Gas in einem einzigen kompakten Klumpen konzentriert ist. Diese Konzentration befindet sich 13 Milliarden Kilometer vom Stern entfernt, was etwa der dreifachen Entfernung zwischen dem Planeten Neptun und der Sonne entspricht. Warum sich das Gas in diesem kleinen Klumpen so weit entfernt vom Stern befindet, bleibt allerdings ein Rätsel. 

„Dieser Klumpen ist ein wichtiger Hinweis auf die Vorgänge in den Außenbereichen dieses jungen Planetensystems“, ergänzt Mark Wyatt von der University of Cambridge in Großbritannien und Koautor des Fachartikels. Es gäbe zwei Wege, auf denen sich so ein Klumpen bilden kann: „Entweder werden die Kometenkollisionen durch die gravitative Anziehung eines noch nicht sichtbaren Planeten mit einer saturnähnlichen Masse auf eine kleine Region konzentriert oder das was wir sehen ist der Überrest einer einzigen katastrophalen Kollision zweier marsähnlicher Eisplaneten.“ 

Beide Möglichkeiten geben Astronomen Anlass zur Hoffnung, dass noch weitere Planeten um Beta Pictoris auf ihre Entdeckung warten. „Kohlenstoffmonoxid ist nur der Anfang – es könnten noch weitere komplexe pre-organische Moleküle aus diesen Eisobjekten freigesetzt worden sein“, fügt Roberge hinzu. 

Weitere Beobachtungen mit ALMA, dessen Kapazitäten immer noch nicht voll entfaltet sind, sind geplant, um mehr Licht in dieses fesselnde Planetensystem zu bringen und somit dabei zu helfen, die Bedingungen zu verstehen, die während der Entstehung des Sonnensystems geherrscht haben.

Endnoten

[1] Viele Sterne sind von wirbelnden Staubwolken, die Trümmerscheiben genannt werden, umgeben. Sie sind die Überreste von Kollisionskaskaden von Gesteinsbrocken in der Umlaufbahn um den Stern, ähnlich wie bei der Zerstörung der Raumstation im Kinofilm Gravity dargestellt, allerdings auf viel größeren Skalen. Von früheren Beobachtungen von Beta Pictoris wurde in eso1024 und eso0842 berichtet. 

[2] Kometen enthalten eisförmiges Kohlenstoffmonoxid, Kohlenstoffdioxid, Ammoniumhydroxid und Methan. Der häufigste Bestandteil ist jedoch eine Mischung aus Staub und Wassereis. 

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Die Position des Sterns Beta Pictoris ist in dieser Aufsuchkarte mit einem roten Kreis im Sternbild Pictor (der Bildhauer) markiert. Wie schon der Name verrät, ist Beta Pictoris der zweithellste Stern in diesem Sternbild. Zusammen mit den meisten Sternen auf dieser Karte ist er mit bloßem Auge unter guten Bedingungen sichtbar.

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Mit seinem Alter von nur 12 Millionen Jahren, oder weniger als einem dreitausendstel des Alters der Sonne, ist Beta Pictoris um 75% massereicher als unsere Sonne. Er befindet sich in einer Entfernung von etwa 20 Lichtjahren von der Erde im Sternbild Pictor (der Bildhauer) und ist eins der bekanntesten Beispiele für einen Stern mit einer staubhaltigen Trümmerscheibe. Frühere Beobachtungen haben eine Wölbung in der Scheibe sichtbar gemacht, eine zweite geneigte Scheibe und kometenartige Objekte, die auf den Stern fallen: alles indirekte, aber sehr suggestive, Anzeichen für die Anwesenheit eines massereichen Planeten. Beobachtungen mit dem NACO-Instrument am Very Large Telescope der ESO in den Jahren 2003, 2008 und 2009 haben nachgewiesen, dass es einen Planeten in der Umlaufbahn um Beta Pictoris gibt. Er befindet sich in einer Entfernung zwischen dem 8- bis 15-fachen der Entfenung Erde-Sonne – oder Astronomischen Einheiten – was etwa der Entfernung zwischen Sonne und Saturn entspricht. Der Planet hat eine Masse von etwa neun Jupitermassen und damit genau die richtige Masse und Position, um die beobachtete Wölbung im Innenbereich der Scheibe zu erklären.

Dieses Bild zeigt, basierend auf Daten aus dem Digitized Sky Survey 2, eine Region von etwa 1,7 mal 2,3 Grad um Beta Pictoris.

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Die ALMA-Aufnahme des Kohlenstoffmonoxids um Beta Pictoris (oben) kann de-projiziert werden (unten) um eine Ansicht von oben auf das System zu simulieren. So wird die große Gaskonzentration in den Außenbereichen von Beta Pictoris deutlich sichtbar. Zum Vergleich der Größenordnungen sind die Planetenbahnen des Sonnensystems eingezeichnet.

Quelle: ESO


2576 Views

Freitag, 7. März 2014 - 09:30 Uhr

Astronomie - Hubble sieht mysteriöses Auseinanderbrechen von Asteroiden

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NASA/ESA Hubble Space Telescope observation of asteroid P/2013 R3. This asteroid has been found to be disintegrating and breaking apart -- the first such body ever seen to do this. This image shows P/2013 R3 as it was seen on Oct. 29, 2013.

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Hubble has observed some weird things since it was launched in 1990, but this is probably one of the strangest.

In September 2013, the Catalina and Pan-STARRS sky surveys spotted a mysterious object in the asteroid belt, a region of rocky debris that occupy the space between the orbits of Mars and Jupiter. Follow-up observations by the Keck Observatory in Hawaii resolved three separate objects within the fuzzy cloud. It was so strange that Hubble mission managers decided to use the space telescope to get a closer look.

And what they saw has baffled and thrilled astronomers in equal measure.

Hubble resolved the slow-moving debris of an asteroid that is in the process of breaking up. The asteroid, designated P/2013 R3, hasn’t hit anything, as the fragments are moving too slow — it just seems to be falling apart. This is unprecedented, never before has an asteroid been seen disintegrating to this degree in the asteroid belt.

“This is a rock. Seeing it fall apart before our eyes is pretty amazing,” said David Jewitt of the University of California, Los Angeles, who led the investigation.

Comets are often seen fragmenting in this way, particularly when they drift too close to the sun; ices sublimate, creating a violent out-gassing of vapor, causing the cometary structure to rupture and break apart. A recent example of a cometary breakup is that of Comet ISON that got shredded by the sun’s extreme heating and powerful tidal forces during Thanksgiving last year.

While analyzing Hubble data, Jewitt’s team could actually see ten separate chunks of asteroid slowly drifting apart — at only 1.5 kilometers per hour (the speed of a slow walk). Four of the largest chunks are around 400 meters wide, roughly four times the length of a football field.

“This is a really bizarre thing to observe — we’ve never seen anything like it before,” said co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany, in a Hubble news release. “The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible.”

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This series of images shows the asteroid P/2013 R3 breaking apart, as viewed by the NASA/ESA Hubble Space Telescope in 2013.

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So what could possibly be causing this asteroid to just fall apart?

With the collision scenario already eliminated, could the break-up be down to ices trapped in the rock heating up and outgassing, causing fragmentation in a similar way to how comets disintegrate? This is unlikely, as there isn’t a significant heat source in the asteroid belt and the asteroid is far away from the sun.

The leading theory for the breakup of P/2013 R3 is a bizarre Yarkovsky–O’Keefe–Radzievskii–Paddack (YORP) effect. As the sun’s radiation heats up one side of a space rock, that heat is radiated away as the asteroid rotates. The infrared radiation that is emitted from the dark side of the asteroid gives the asteroid a tiny kick. Over millions of years, this tiny acceleration effect can cause the asteroid to “spin up.” Should the spinning become faster than the structure of the asteroid can hold itself together, centrifugal forces can literally rip it apart.

As many asteroids are believed to be loose collections of rocks and dust — known as “rubble piles” — the impact of the YORP effect can be pretty dramatic, as P/2013 R3 can attest.

“This is the latest in a line of weird asteroid discoveries, including the active asteroid P/2013 P5, which we found to be spouting six tails,” says Agarwal. “This indicates that the sun may play a large role in disintegrating these small solar system bodies, by putting pressure on them via sunlight.”

This recent asteroid belt oddity comes hot on the heels of another disintegrating space rock, P/2013 P5, that was observed to have very comet-like qualities. The dusty three six tails of P/2013 P5 is also strong evidence for the YORP effect causing the asteroid to spin up and eject material from its equator.

While observing the expanding mass of debris, astronomers have estimated that there are 200,000 tons of material expanding to a volume the size of Earth.

As Hubble continues to study these strange findings in the asteroid belt, we are finding that a little solar heating over thousands to millions of years can have a dramatic impact on large asteroids, once again proving that our solar system is a dynamic and fascinating place.

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Hubble's Bizarre X-Shaped Slow-Motion Asteroid Collision

In January, something mysterious was spotted lurking in the asteroid belt between the orbits of Mars and Jupiter. The eerie comet-like feature — sporting a long tail of dust being swept back by the sun’s radiation pressure — was thought to be a rare asteroid/comet hybrid, but when the Hubble Space Telescope took a closer look, a bizarre shape formed.

An “X” pattern emerged, revealing to astronomers that they were actually looking at the site of a recent (and equally as rare) asteroid-on-asteroid collision a little over 100 million miles from Earth. The pattern was believed to be the debris of the smash expanding into space. However, all’s not what it seems.

BIG PIC: Mystery Comet or Asteroid Collision?

 

According to Hubble scientists that have been tracking the debris cloud (called P/2010 A2), the asteroid collision didn’t happen recently, it actually happened last year, most likely around February or March 2009.

“We thought this event had just occurred,” said David Jewitt, UCLA astronomer and lead scientist of the Hubble observation, in today’s press release. “We expected the debris field to expand dramatically, like shrapnel flying from a hand grenade.”

This chance observation by ground observatories caused a rush to get Hubble turned around and look at the event. After all, catching a once-in-a-lifetime glimpse of the exploding debris of colliding two space rocks would be over quickly. But in actuality, the debris cloud was expanding much slower than expected.

“We found that the object is expanding very, very slowly and that it started not a week but nearly a year before our January observations,” Jewitt added.

Although asteroid collisions are predicted to occur roughly once a year, spotting the resulting debris cloud requires a lot of luck. These events are crucial to our understanding of how the solar system — and other star systems — evolved, hence the rush to use Hubble to analyze P/2010 A2.

“These observations are important because we need to know where the dust in the solar system comes from, and how much of it comes from colliding asteroids as opposed to ‘outgassing’ comets,” Jewitt continues. “We can also apply this knowledge to the dusty debris disks around other stars, because these are thought to be produced by collisions between unseen bodies in the disks. Knowing how the dust was produced will yield clues about those invisible bodies.”

Hubble kept an eye on P/2010 A2 from January to May 2010, resolving a point-like object approximately 120 meters wide followed by the X-shaped debris field. It is thought the 120-meter-wide object is what remains of the larger asteroid after impact. The smaller asteroid is estimated to have been 3 to 5 meters wide before it was pulverized. The pair were probably traveling at a speed of 11,000 miles per hour, generating an explosion of comparable energy to the detonation of a small nuclear weapon.

The X-shape was most likely caused by the irregular shape of one or both of the asteroids — if they were smooth and spherical, the debris cloud would have been far more symmetrical.

It’s events like these that remind us that we are still in an evolving and dynamic solar system where asteroids are still grinding away, shattering and occasionally generating some powerful fireworks. What’s more, if the collision of P/2010 A2 is typical, perhaps astronomers have more time to look out for the debris clouds of these space rock clashes.

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Quelle: D-News

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Astronomers witness mysterious, never-before-seen disintegration of asteroid

Astronomers have witnessed for the first time the breakup of an asteroid into as many as 10 smaller pieces. The discovery is published online March 6 in Astrophysical Journal Letters.
 
Though fragile comet nuclei have been seen falling apart as they near the sun, nothing resembling this type of breakup has been observed before in the asteroid belt. NASA's Hubble Space Telescope photographed the demolition.
 
"Seeing this rock fall apart before our eyes is pretty amazing," said David Jewitt, a professor in the UCLA Department of Earth, Planetary and Space Sciences and the UCLA Department of Physics and Astronomy, who led the astronomical forensics investigation.
 
The crumbling asteroid, designated P/2013 R3, was first noticed as an anomalous, fuzzy-looking object on Sept. 15, 2013, by the Catalina and Pan-STARRS sky-survey telescopes. A follow-up observation on Oct. 1 with the W.M. Keck telescope on Hawaii's Mauna Kea revealed three co-moving bodies embedded in a dusty envelope that is nearly the diameter of Earth.
 
"The Keck telescope showed us that this asteroid was worth looking at with Hubble," Jewitt said.
 
With its superior resolution, the Hubble telescope revealed that there were really 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 200 yards in radius, about twice the length of a football field.
 
The Hubble data showed that the fragments are drifting away from each other at a leisurely pace of one mile per hour — slower than a strolling human. The asteroid began coming apart early last year, but new pieces continue to emerge in the most recent images.
 
This makes it unlikely that the asteroid is disintegrating because of a collision with another asteroid, which would be instantaneous and violent. Some of the debris from such a high-velocity smash-up would also be expected to travel much faster than observed.
 
Nor is the asteroid coming unglued due to the pressure of interior ices warming and vaporizing, Jewitt said. The asteroid is too cold for ices to significantly sublimate, and it has presumably maintained its nearly 300 million–mile distance from the sun for much of the age of the solar system, he said.
 
This leaves a scenario in which the asteroid is disintegrating due to a subtle effect of sunlight, which causes the rotation rate to slowly increase. Eventually, its component pieces, like grapes on a stem, gently pull apart due to centrifugal force, Jewitt said. The possibility of disruption by this so-called "YORP torque" has been discussed by scientists for several years but, so far, never reliably observed.
 
For this to happen, P/2013 R3 must have a weak, fractured interior, probably as the result of numerous ancient but non-destructive collisions with other asteroids. Most small asteroids, in fact, are thought to have been severely damaged in this way, giving them a "rubble pile" internal structure. P/2013 R3 itself is probably the product of collisional shattering of a bigger body some time in the last billion years.
With Hubble's recent discovery of an active asteroid spouting six tails (P/2013 P5), astronomers are seeing more circumstantial evidence that the pressure of sunlight may be the primary force that disintegrates small asteroids (less than a mile across) in the solar system.
 
The asteroid's remnant debris, weighing in at 200,000 tons, in the future will provide a rich source of meteoroids, Jewitt said. Most will eventually plunge into the sun, but a small fraction of the debris may one day enter the Earth's atmosphere to blaze across the sky as meteors, he said.
 
Jewitt, who is on the faculty of the UCLA College of Letters and Science, is a member of the National Academy of Sciences and a fellow of both the American Association for the Advancement of Science and the American Academy of Arts and Sciences. He co-discovered the Kuiper Belt beyond Neptune in 1993. The discovery of the belt, which contains more than a billion objects and was once believed to be empty space, has fundamentally changed the modern perception of the solar system.
 
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
 
"Hubble's incredible resolution and sensitivity are creating a new cottage industry for planetary scientists," said Hal Weaver, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., one of Jewitt's co-investigators.
Quelle: UCLA

3111 Views

Donnerstag, 6. März 2014 - 20:05 Uhr

Astronomie - ESA-Radar spürt erste Trümmerteile im All auf

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Installation of the new test radar developed by Indra (Spain) and FHR (Germany), in Spain, September 2012. The space debris radar will begin testing in 2014 as part of the Agency's Space Situational Awareness (SSA) programme.

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Ein Radar-Prototyp, der Europas Möglichkeiten zur Überwachung von Weltraumschrott verbessern soll, liefert Ergebnisse, die alle Erwartungen übertreffen. Wie Tests zeigen, ist er imstande, Objekte in erdnahen Umlaufbahnen zu erkennen. Das Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik (FHR) war an dem Projekt beteiligt.

Der Radar wurde in der Umgebung der spanischen Hauptstadt Madrid installiert und nach einer umfassenden Testphase im November von der Industrie an die ESA übergeben.

Dieser neuartige Sensor verfügt über grundlegende Technologien, um Weltraumschrott in erdnahen Umlaufbahnen zu entdecken und zu verfolgen - ein wichtiger Schritt für die Entwicklung operationeller Radarsysteme. Der Ausbau solcher Warnkapazitäten für drohende Kollisionen spielt eine wichtige Rolle für die Sicherheit europäischer Satelliten in niedrigen und mittleren Erdumlaufbahnen.

Der Testradar ist bereits heute imstande, Objekte von etwa einem Meter Größe aufzuspüren, abhängig von deren Flughöhe und weiteren Faktoren. Dies ist zwar für die erforderliche Leistung eines operationellen Systems noch nicht ganz ausreichend – dazu müsste der Radar Objekte mit einem Durchmesser von zehn Zentimetern oder weniger erkennen – allerdings reichen die Ergebnisse aus, um neue Technologien und Methoden zu verifizieren und zu verbessern. 

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Landsat 5 followed by radar

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Der Radar befindet sich in einem gesicherten Bereich. Sämtliche Test- und Validierungsaktivitäten werden nach vereinbarten ESA-Datenrichtlinien – den sogenannten Space Situational Awareness (SSA) Programme Security Instructions – durchgeführt, die eigens für diese Installation festgelegt wurden. Bei den Tests werden die Radardaten gefiltert und mit einer „weißen Liste“ autorisierter Weltraumobjekte verglichen, bevor sie zur weiteren Bearbeitung und Katalogisierung an das ESA-SSA-System gegeben werden.

„Während der Abnahmetests hat sich gezeigt, dass der Radar exzellente Leistungen erbringt”, berichtet Gian Maria Pinna, Ground Segment Manager im SSA-Programmbüro. „Sogar ohne eine vollständige Kalibrierung des Systems, welche mehrere Monate in Anspruch nehmen würde, konnten wir kleinere Objekte in größerer Reichweite als erwartet erkennen. Ein anschauliches Beispiel dafür ist Landsat-5 mit einem Radardurchmesser von lediglich 3,6 Metern und einer verhältnismäßig großen Flughöhe von 537 Kilometern.“

Während der Testbeobachtung der Internationalen Raumstation ISS im Januar erkannten die Ingenieure zu ihrer großen Überraschung ein weiteres Objekt. „In dem Moment wurde uns bewusst, dass wir die Abkopplung des sehr viel kleineren Raumfrachters Cygnus von der Raumstation beobachtet hatten.“ Der Radar erkannte ebenso die ESA-Satelliten GOCE und Swarm, Weltraumschrott aus abgeschlossenen Startphasen sowie weitere etwa ein Meter große Objekte.

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ISS und Cygnus auf dem Radar

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Schätzungen zufolge fliegen über 700.000 potenziell gefährliche Trümmerteile im Weltraum umher – viele davon nur ein bis zwei Zentimeter groß – die aktive Satelliten beschädigen oder zerstören könnten. Jegliche Betriebsstörungen oder Ausfälle an Satelliten haben erstzunehmende Folgen für eine Vielzahl von kommerziellen und zivilen Aktivitäten wie den kommerziellen Land-, Luft- und Seetransport, die Schiffsnavigation, Telekommunikation, Informationstechnologie und -netzwerke, Rundfunk, Klimaüberwachung, Wettervorhersagen und vieles mehr.

 

Für die Entwicklung des Radars wurde auch Know How aus Deutschland herangezogen: Der 4,7-Millionen-Euro-Vertrag zum Bau des Radars wurde 2010 vom SSA-Programmbüro der ESA und dem spanischen Technologieexperten Indra Espacio unterzeichnet. Indra Espacio leitet ein Konsortium bestehend aus Indra und dem deutschen Fraunhofer-Institut für Hochfrequenzphysik und Radartechnik (FHR) in Wachtberg bei Bonn. Das FHR war dabei für den gesamten Entwurf, die Entwicklung, die Integration und Kalibrierung des Radar-Empfangssystems verantwortlich. Dies umfasste die Antenne sowie das Signalverarbeitungssystem.

Der Testradar zeichnet sich durch sein „monostatisches“ Design aus, bei dem Sender und Empfänger in wenigen Hundert Metern Entfernung positioniert sind. Er wird durch einen zweiten Testradar mit „bistatischem“ Design ergänzt, bei dem Sender und Empfänger geografisch voneinander getrennt sind. Dieser zweite Radar wird von einem Konsortium unter der Leitung des französischen Forschungszentrums ONERA entwickelt und verfügt über eine Reihe von optischen und laserbasierten Teleskopen zur Überwachung und Objektverfolgung in entfernteren Umlaufbahnen.

„Die erfolgreiche Abnahme der ersten Komponente eines solch komplexen Sensoren-Netzwerks stellt einen wichtigen Meilenstein für das SSA-Programm der ESA dar”, sagt Programmleiter Nicolas Bobrinsky. „Die Technologien, die im Rahmen des Programms entwickelt werden, bilden den Grundstein für zukünftige Betriebssysteme, die Europa einsetzen könnte, um seine Satelliten vor den Gefahren durch Weltraumschrott zu schützen.“

Quelle: ESA


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