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Sonntag, 22. Dezember 2013 - 20:00 Uhr

Luftfahrt - DODfast: Laserkommunikation zwischen Jet und Bodenstation

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DODfast Bodenstation

DODfast Teleskop

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Forschern des Deutschen Zentrums für Luft- und Raumfahrt (DLR) ist es erstmals gelungen, eine Laser-Kommunikationsverbindung zu einem sehr schnellfliegenden Flugzeug zu demonstrieren.

Moderne Kamerasysteme zur Aufnahme von Luftbildern erzeugen eine große Menge an Daten. Herkömmliche Anlagen basieren auf klassischer Funkübertragung und unterliegen physikalischen und regulatorischen Einschränkungen, welche die Übertragungsraten im praktischen Einsatz stark begrenzen. "Sollen die aufgenommenen Bilder schnell zur Auswertung bereit stehen und bereits während des Fluges zu einer Bodenstation übertragen werden, stellt die zur Verfügung stehende Kommunikationsverbindung häufig den Flaschenhals bei der Übertragung dar", beschreibt Professor Christoph Günther, Direktor des DLR-Instituts für Kommunikation und Navigation, die Herausforderung.

Laser-Datenübertragungssysteme können wesentlich höhere Datenraten erreichen als die Übertragung mit Mikrowellen. Sie sind außerdem kompakter und leistungsfähiger als klassische Funkgeräte und darüber hinaus nur schwer abzuhören. "Wir haben bei den Versuchen eine Datenrate von 1,25 Gigabit pro Sekunde erzielt. Dies entspricht etwa der 100-fachen Geschwindigkeit eines Standard-DSL Anschlusses", erklärt Projektleiter Florian Moll vom DLR-Institut für Kommunikation und Navigation in Oberpfaffenhofen. Als Flugträger während der Testphase des Projekts DODfast (Demonstration of an Optical Data link fast) bis zum 11. Dezember 2013 diente ein Panavia Tornado der Bundeswehr.

Eine einzigartige Demonstration

Das Experiment zum Test der aeronautischen Laserkommunikation fand in Manching bei Ingolstadt statt. Als Gegenstation diente die am DLR entwickelte Transportable Optische Bodenstation TOGS (Transportable Optical Ground Station). Sie wurde in der Nähe des Flughafens aufgestellt, von dem aus der Jet für mehrere Experimentalflüge startete. Das Flugzeug war mit einem unter dem Rumpf angebrachten, etwa 2,5 Meter langen Behälter, einem sogenannten Pod, ausgerüstet, in dem die gesamte Hardware für das Experiment installiert war. Zu dieser gehörte eine Aufklärungskamera, ein spezielles System zum Übertragen der Bilder und das Sendeterminal für die Laserkommunikation. Die Kamera und das Streaming-System wurden vom Auftraggeber Cassidian gestellt. Das Sendeterminal, das sogenannte Micro Laser Terminal (MLT), wurde durch die DLR-Ausgründung ViaLight Communications in Zusammenarbeit mit dem DLR entwickelt.

Die besondere Herausforderung des Experiments lag darin, die Laserstahlen zwischen TOGS und MLT genau aufeinander auszurichten. Die TOGS musste dabei mit hoher Präzision die Bewegung des Flugzeugs verfolgen, um das Laserlicht auf der winzigen Fotodiode fokussiert zu halten. An das MLT waren die Ansprüche noch größer. Es mussten nicht nur die schnellen Lageänderungen des Tornados, sondern auch dessen starke Vibrationen ausgelichen werden. Die Ziel- und Ausrichtegenauigkeiten gingen dabei bis in den Bereich eines tausendstel Grads. "Eine anspruchsvolle Aufgabe, insbesondere bei einem Düsenflugzeug mit hoher Fluggeschwindigkeit", so Florian Moll. "Wir hatten zwar Erfahrung mit solchen Experimenten auf unserer Propellermaschine Do228, aber bei einem Jet war die Herausforderung enorm - vorallem durch die Vibrationen an Bord und die atmosphärischen Effekte, die den Laserstrahl beeinflussen. Wir haben aber alle technischen Herausforderungen in den Griff bekommen." Bereits beim ersten Flug gelang trotz widrigen Wetterbedingungen die Bildübertragung. Beim zweiten Flug und besserem Wetter konnte das System seine volle Leistung unter Beweis stellen. Die Wissenschaftler demonstrierten die Datenverbindung bei hoher Unterschallgeschwindigkeit des Flugträgers.

Fortgeschrittene Systemtechnik

Das auf dem Tornado eingesetzte Laserkommunikationssystem basiert auf der DLR-Entwicklung für das Forschungsflugzeug Do228 und besteht aus zwei Einheiten: Außen am Rumpfbehälter  befindet sich die Grobausrichteeinheit. Diese wird durch eine kleine Glaskuppel, nicht viel größer als eine Kaffeetasse, geschützt. Hinzu kommt eine Feinausrichte-Einheit im Inneren des Behälters. Eine spezielle Sensorik und ein sehr schneller, beweglicher Spiegel sorgen dafür, dass die Vibrationen des Flugzeugs ausgeglichen werden, und dass die Ausrichtung des Laserstrahls stabil bleibt. Zusätzlich wird der Sendelaser auch für das optische Tracking auf der Bodenstationsseite, also für die automatische Verfolgung des Flugzeugs eingesetzt. Hier empfängt das Teleskop das Laserlicht und leitet dieses auf Datenempfänger und Trackingsensor, welcher für die hochgenaue Bestimmung der Flugzeugposition und die Nachführung des Teleskops verwendet wird.

Auf dem Weg zur Einsatzreife

Es fehlt nicht mehr viel, um die Lasertechnik in der aeronautischen Kommunikation einzusetzen. "Der Außenanbau ist auf ein Minimum reduziert und dementsprechend klein. Die gesamte Sensorik und Steuerungseinheit befindet sich in einem kleinen, integrierten Gehäuse. Da ist sogar noch Potenzial zur Verkleinerung drin", erklärt der Entwickler des MTL, Joachim Horwath von ViaLight Communications.

Auch die Bodenstation TOGS hat bei ihrem Einsatz die volle Entwicklungsreife bewiesen. Die transportable Station, die Anfang des Jahres 2013 eingeweiht wurde, wird genutzt, um die Einsatzmöglichkeiten der Laserkommunikation für lange Übertragungsstrecken zwischen Flugzeugen, Satelliten und Bodenstation zu testen und zu demonstrieren.

"Mit diesem Versuch ist ein weiterer Nachweis für die Verwendbarkeit der Laserkommunikation erbracht. Das Szenario war extrem anspruchsvoll. Unser nächstes großes Ziel ist es Kommunikationssatelliten mit dem Internet über Laserlinks zu verbinden und damit die Internetversorgung in ländlichen Gebieten zu verbessern. Wir wollen gewissermaßen das Äquivalent der Glasfaser für Kommunikationssatelliten schaffen", so Professor Günther zur zukünftigen Entwicklung.

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Integration des Sendeterminals

DODfast Luftwaffe Tornado

Quelle: DLR

 


Tags: DODfast: Laserkommunikation 

3481 Views

Sonntag, 22. Dezember 2013 - 19:45 Uhr

Raumfahrt - Re-Entry-Ankündigung für Molniya-3-45 Satelliten

.2.10.2013

Russian satellite Molniya-3-45 may fall on Earth on January 1, 2014 - forecast
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Forty-five of the 158 launched communication spacecraft Molniya now remain on the orbits of artificial Earth satellites and 12 of them are expected to end their ballistic existence by 2030, the Interstate Joint-Stock Corporation (MAK) Vympel (part of the concern PVO Almaz-Antei) told Interfax-AVN on Wednesday.
"The first of them, Molniya-3-45, may cease its ballistic existence on January 1, 2014. This date is a tentative one and was obtained based on a study of the trajectory parameters as of March 23, 2013 and may be specified later," MAK Vympel said."
"According to the corporation experts' estimations, 33 of these 45 spacecraft will fall on Earth after 2030 and 12 before 2030," the source said.
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1993 August 4 - . 00:52 GMT - . Launch Site: Plesetsk. Launch Complex: Plesetsk LC43/3. LV Family: R-7. Launch Vehicle: Molniya 8K78M. LV Configuration: Molniya 8K78M-ML.
Molniya 3-45 - . Payload: Molniya-3 s/n 58. Mass: 1,600 kg (3,500 lb). Nation: Russia. Agency: MOM. Program: Molniya. Class: Communications. Type: Military communications satellite. Spacecraft: Molniya-3. USAF Sat Cat: 22729 . COSPAR: 1993-049A. Apogee: 37,920 km (23,560 mi). Perigee: 2,500 km (1,500 mi). Inclination: 64.4000 deg. Period: 719.10 min. Summary: Operation of the long range telephone and telegraph radio-communications system. Replaced Molniya 3-37..
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Russian communications satellite. 55 launches, 1974.11.21 (Molniya 3-01) to 2003.06.19 (Molniya 3-53). Development of the Molniya-2M communications satellite, later called Molniya-3, began in 1972. Flight trials began in November 1974.
The Molniya-3 group of four satellites was used to create the Orbita communications system for northern regions of the Soviet Union. The land segment used a 12 m diameter parabolic antenna, pointed automatically at the satellite using autonomous electromechanical equipment. Although primarily for civilian applications, later versions were part of the Soviet YeSSS Unified Satellite Communications System. Trials of this version began in the 1980's, with the system being accepted by the military in 1983-1985.
Molniya-3 used the Segment-3 three-channel repeater (cm-band, 4-6 GHZ). The Molniya 3 spacecraft supported civil communications (domestic and international) while Molniya-1T were used almost exclusively for military communications. Compared to Molniya-1T they had a slightly enhanced electrical power system and a communications payload of three 6/4 GHz transponders with power outputs of 40 W or 80 W. Molniya 3 spacecraft only originated from Plesetsk.
Until 1983 the Molniya 3 constellation consisted of only four satellites, which were essentially co-located with four Molniya 1 satellites. When the Molniya 3 system was expanded to eight vehicles as part of the military's YeSSS system in 1983-1985, the new additions inaugurated the 155 degrees E ascending node geometry. After the restructuring of the Molniya-1T constellations in 1991, the Molniya 1 and 3 systems were essentially the same from a deployment perspective and to some extent provided an inherent backup capability. On the average Molniya-3 spacecraft were replaced slightly less frequently than their Molniya 1 cousins, representing either an extra 5 to 6 months of operational life, or a more casual attitude to having redundant civilian as opposed to military capability.
AKA: Molniya-2M; 11F637. 
Gross mass: 1,600 kg (3,500 lb). 
Height: 4.40 m (14.40 ft). 
Span: 8.20 m (26.90 ft). 
First Launch: 1974.11.21. 
Last Launch: 2003.06.19. 
Number: 55 .
Quelle: Interfax 
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Update: 16.12.2013
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Soviet Oko satellite may fall on Earth on December 18
MOSCOW. An old Soviet satellite, a part of the OKO system, which was a space echelon of the missile attack warning system, may fall to Earth on December 18, the information analysis center of the Interstate Joint-Stock Corporation (MAK) Vympel (part of the concern PVO Almaz-Antei) told Interfax-AVN on Monday.
"A satellite of the Oko system is expected to fall around December 18, the day after tomorrow. It was launched in the USSR and was intended to detect ballistic missile launches. This satellite has not been working for a long time and is going down from an orbit on which Molniya-type satellites worked," the source said.
Quelle: INTERFAX
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Update: 22.12.2013
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Oko system satellite burns down above Southern Hemisphere

MOSCOW. Dec 22 Updated reports say the Kosmos-2393 satellite integrated in the Oko system, the space component of Russia's early warning system ceased to exist last night, Interfax-AVN was told at the Vympel interstate joint-stock company, which is part of the Almaz-Antei air defense corporation on Sunday.

"According to updated reports of Vympel, the satellite ceased to exist at 1:26 a.m. After entering the atmosphere it started disintegrating, " a spokesperson said.

The U.S. space control system confirmed the early reports from Vympel.

Quelle: INTERFAX


Tags: 2014 

4523 Views

Sonntag, 22. Dezember 2013 - 12:00 Uhr

Raumfahrt - China fördert das Mondpalast-Projekt "Yuegong Nr. 1"

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Die chinesische Mondsonde "Change 3" landete am vergangengen Samstag auf dem Mond. Nach der erfolgreichen Landung haben Chinas erstes Mondfahrzeug "Yutu" und die Landesonde einander am Sonntag fotografiert. Es ist ein wichtiger Erfolg für die chinesische Raumfahrt. Aber wann kann die Menschheit langfristig auf dem Mond leben?Nur wenige Menschen wissen, dass China gerade das Projekt "Yugong Nummer 1" und die Vorbereitungsarbeiten für eine mögliche Mondsiedlung fördert.

"Yuegong" bedeutet auf Deutsch "Mondpalast". Liu Hong, Professorin an der Beihang University, ist für das Projekt zuständig. Ihr zufolge sollen in einem abgeschlossenen Recycling-System Gemüse, Getreide und Obst angebaut werden, damit die Bedürfnisse der Experimentteilnehmer nach Luft, Wasser und Lebensmitteln befriedigt werden können. Das Projekt soll um das chinesische Frühlingsfest (31. Januar) der Öffentlichkeit präsentiert werden.

Liu teilte noch mit, "Yuegong" wurde Ende Oktober gerade fertiggestellt und begann mit einem Experiment. Wissenschaftler sollen versuchen, in dem geschlossenen System zu leben.

Quelle: german.china.org.cn


2821 Views

Sonntag, 22. Dezember 2013 - 10:49 Uhr

Astronomie - Hubble verfolgt das Wachstum der Milchstraße-wie der Galaxien

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This composite image shows examples of galaxies similar to our Milky Way at various stages of construction over a time span of 11 billion years.

The galaxies are arranged according to time. Those on the left reside nearby; those at far right existed when the cosmos was about 2 billion years old. The bluish glow from young stars dominates the color of the galaxies on the right. The galaxies at left are redder from the glow of older stellar populations.

Astronomers found the distant galaxies in two Hubble Space Telescope surveys: 3D-HST and the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, or CANDELS. The observations were made in visible and near-infrared light by Hubble's Wide Field Camera 3 and Advanced Camera for Surveys. The nearby galaxies were taken from the Sloan Digital Sky Survey.

This image traces Milky Way-like galaxies over most of cosmic history, revealing how they evolve over time. Hubble's sharp vision resolved the galaxies' shapes, showing that their bulges and disks grew simultaneously.

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Hubble Sees a Stellar "Sneezing Fit"

Look at the bright star in the middle of this image. It appears as if it just sneezed. This sight will only last for a few thousand years — a blink of an eye in the young star's life.

If you could carry on watching for a few years you would realize it's not just one sneeze, but a sneezing fit. This young star is firing off rapid releases of super-hot, super-fast gas, like multiple sneezes, before it finally exhausts itself. These bursts of gas have shaped the turbulent surroundings, creating structures known as Herbig-Haro objects.

These objects are formed from the star's energetic "sneezes."  Launched due to magnetic fields around the forming star, these energetic releases can contain as much mass as our home planet, and cannon into nearby clouds of gas at hundreds of kilometers/miles per second. Shock waves form, such as the U-shape below this star. Unlike most other astronomical phenomena, as the waves crash outwards, they can be seen moving across human timescales of years. Soon, this star will stop sneezing, and mature to become a star like our sun.

This region is actually home to several interesting objects. The star at the center of the frame is a variable star named V633 Cassiopeiae, with Herbig-Haro objects HH 161 and HH 164 forming parts of the horseshoe-shaped loop emanating from it. The slightly shrouded star just to the left is known as V376 Cassiopeiae, another variable star that has succumbed to its neighbor's infectious sneezing fits; this star is also sneezing, creating yet another Herbig-Haro object — HH 162. Both stars are very young and are still surrounded by dusty material left over from their formation, which spans the gap between the two.

Quelle: NASA


2655 Views

Samstag, 21. Dezember 2013 - 23:21 Uhr

Astronomie - Sternenlose Wolkenkerne enthüllen warum einige Sterne größer als Andere sind

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This image shows the ALMA data overlaid on an artist’s impression background. The ALMA data show two main cores as imaged by emission from the molecular ion N2D+ (two nitrogen and one deuterium atom). The core on the right is particularly bright and rounded, suggesting it is self-gravitating and poised to form a massive, single star – a very rare occurrence in star formation. The other core appears more distorted and fragmented, potentially leading to the formation of multiple lower-mass stars. This fragmentation is a normal process in star-forming clouds.

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Massive stars – those at least 8 times the mass of our Sun – present an intriguing mystery: how do they grow so large when the vast majority of stars in the Milky Way are considerably smaller?

To find the answer, astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) telescope to survey the cores of some of the darkest, coldest, and densest clouds in our Galaxy to search for the telltale signs of star formation.

These objects, known as Infrared Dark Clouds, were observed approximately 10,000 light-years away in the direction of the constellations of Aquila and Scutum.


Since these cloud cores are so massive and dense, gravity should have already overwhelmed their supporting gas pressure, allowing them to collapse to form new, Sun-mass stars. If a star had not yet begun to shine, that would be a hint that something extra was supporting the cloud.

“A starless core would indicate that some force was balancing out the pull of gravity, regulating star formation, and allowing vast amounts of material to accumulate in a scaled-up version of the way our own Sun formed,” remarked Jonathan Tan, an astrophysicist at the University of Florida, Gainesville, and lead author of a paper published today in the Astrophysical Journal. “This suggests that massive stars and Sun-like stars follow a universal mechanism for star formation. The only difference is the size of their parent clouds.”

Average stars like our Sun begin life as dense, but relatively low-mass concentrations of hydrogen, helium, and other trace elements inside large molecular clouds. After the initial kernel emerges from the surrounding gas, material collapses under gravity into the central region in a relatively ordered fashion via a swirling accretion disk, where eventually planets can form. After enough mass accumulates, nuclear fusion begins at the core and a star is born.

While this model of star formation can account for the vast majority of stars in our Milky Way, something extra is needed to explain the formation of more massive stars. “Some additional force is needed to balance out the normal process of collapse, otherwise our Galaxy would have a fairly uniform stellar population,” said Tan. “Alternatively, there has been speculation that two separate models of star formation are needed: one for Sun-like stars and one for these massive stars.”

The key to teasing out the answer is to find examples of massive starless cores – to witness the very beginnings of massive star birth.

The team of astronomers from the United States, the United Kingdom, and Italy used ALMA to look inside these cores for a unique chemical signature involving the isotope deuterium to essentially take the temperatures of these clouds to see if stars had formed. Deuterium is important because it tends to bond with certain molecules in cold conditions. Once stars turn on and heat the surrounding gas, the deuterium is quickly lost and replaced with the more common isotope of hydrogen.

The ALMA observations detected copious amounts of deuterium, suggesting that the cloud is cold and starless. This would indicate that some counter force is forestalling core collapse and buying enough time to form a massive star. The researchers speculate that strong magnetic fields may be propping up the cloud, preventing it from collapsing quickly.

“These new ALMA observations reveal objects that are quite similar to the nurseries of Sun-like stars, but simply scaled-up by tens or a hundred times. This may mean that nature is more important than nurture when it comes to determining a star’s size," concludes Tan.

These observations were conducted during ALMA’s early science campaign. Future studies with ALMA’s full array of 66 antennas will uncover even more details about these star-forming regions.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.



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This image from ALMA shows two main cores as imaged by emission from the molecular ion N2D+ (two nitrogen and one deuterium atom). The core on the right is particularly bright and rounded, suggesting it is self-gravitating and poised to form a massive, single star – a very rare occurrence in star formation. The other core appears more distorted and fragmented, potentially leading to the formation of multiple lower-mass stars. This fragmentation is a normal process in star-forming clouds.

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Quelle: NRAO


2789 Views

Samstag, 21. Dezember 2013 - 23:00 Uhr

Raumfahrt - 1. ISS-Spacewalk (EVA-24) für Reparatur von Ammoniak Kühlschleifen

.21.12.2013 / 19.00 MEZ

LIVE-Frams von EVA-24

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Quelle: NASA

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Update: 21.12.2013 / 23.00 MEZ

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Spacewalkers do repairs more quickly than expected — and stay dry

Two NASA spacewalkers started fixing the International Space Station's cooling system more quickly than expected on Saturday, with no sign of the helmet-flooding problem that led NASA to outfit astronauts with snorkels for the first time.

Astronauts Rick Mastracchio and Mike Hopkins finished the first of three planned spacewalks in five and a half hours — an hour ahead of schedule. They moved so quickly that they got extra work done, stowing away a coolant pump module with a faulty valve to make room for its replacement. And if their next spacewalk goes as smoothly on Monday, they could dispense with the third outing and take Christmas Day off.

"Really nice work, guys," fellow NASA astronaut Doug Wheelock told the dynamic space duo from Mission Control. Wheelock was involved in a similar pump replacement operation in 2010.

Last week's valve malfunction cut the station's cooling capability in half, forcing mission managers to shut down non-critical systems on the $100 billion-plus orbital outpost. Ground controllers couldn't get the valve back in service by remote control, which led to the plan for three spacewalks.

Worries about water
Replacing the refrigerator-sized pump module is one of the station's expected maintenance tasks — but the job has been complicated by the fact that an Italian spacewalker, Luca Parmitano, almost drowned in July when water pooled in the helmet of his U.S.-made suit.

That incident led NASA to suspend U.S. spacewalks while the station's crew and controllers worked to track down the source of the problem. They think they've identified the cause: previously undetected contamination that clogged up the system designed to remove moisture from the suit. And they gave a clean bill of health to the spacesuits Mastracchio and Hopkins are using.

But just to be safe, the astronauts wore absorbent pads on their necks that should have picked up the first signs of excess moisture in the helmet — and they were primed to stop the spacewalk if those pads started feeling squishy. They also had jury-rigged snorkel tubes within easy reach of their mouths in the event that water started to cover their faces.

Mastracchio and Hopkins told Mission Control they didn't feel a bit of squishiness, raising the confidence level for future spacewalks.

Three spacewalks, or two?
This was the seventh career spacewalk for Mastracchio — and the first one for Hopkins, who wore the suit that Parmitano used in July. During Saturday's outing, they disconnected cables and fluid lines attached to the faulty pump module, and hooked up a jumper box to keep the liquid ammonia coolant from leaking out.

That took care of all the originally assigned duties. Then, with Mission Control's go-ahead, they pulled out the pump module and hooked it onto a storage fixture. Japanese astronaut Koichi Wakata helped out from inside the station by operating the 58-foot-long (18-meter-long) robotic arm.

One of the potential perils that the spacewalkers faced was exposure to toxic ammonia. At one point, Mastracchio reported that some "very small flakes" of frozen ammonia floated out of one of the fluid lines and landed on his spacesuit. Fortunately, the ammonia contamination was "baked out" of the suit through exposure to sunlight.

Mission Control told the spacewalkers they could start preparations to install the spare pump module if they wanted to, but Mastracchio said he preferred to "call it a day." The spacewalk, which was originally planned to last six and a half hours, ended at 12:29 p.m. ET — five hours and 28 minutes after it began.

During Monday's spacewalk, the astronauts are scheduled to install the spare pump module, which has been in storage on the space station's exterior. Because they were able to work ahead on Saturday, they may be able to finish the repair job in two spacewalks and forget about the third one on Christmas Day.

One lighthearted exchange reflected the holiday spirit: When Mastracchio grabbed hold of a ring that was part of the pump module assembly, Wheelock told him, "Don't let that go — that's a stocking stuffer."

"Don't tell my wife," Mastracchio replied.

Repercussions weighed
The cooling system problem poses no immediate danger to the crew, but it does reduce the safety margin on the station. If the second coolant loop were to fail, urgent action would be required — and in a worst-case scenario, the station would have to be abandoned.

The situation already has forced NASA to delay the launch of a cargo resupply mission until Jan. 7 at the earliest. NASA sources say they are also studying whether last week's glitch resulted in damage to Europe's Columbus laboratory.

And as if the six-man crew didn't have enough to worry about, NASA reported in an advisory that one of the toilets on the station has broken down.

In addition to Hopkins, Mastracchio and Wakata, the space station is home to three Russian cosmonauts: station commander Oleg Kotov, Mikhail Tyurin and Sergey Ryazanskiy. The 450-ton structure has been continuously occupied since 2000.

Quelle: NBC-News


Tags: First ISS-Spacewalk (EVA-24) 23 and 25 US Spacewalk 24 

2644 Views

Samstag, 21. Dezember 2013 - 16:15 Uhr

Raumfahrt - Weltgrößte Sonnensegel, Sunjammer, schließt erfolgreich Test ab. Bringt damit Propellantless Space Technology einen Schritt näher zur Realität.

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2.10.2013

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World’s Largest Solar Sail, Sunjammer, Completes Successful Test. Brings Propellantless Space Technology One Step Closer to Reality
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Tustin, CA - NASA officials, team partners, and local students were on hand to witness a key milestone for the Sunjammer Mission as it successfully deployed a quadrant of its solar sail - a critical design component that will eventually herald an era of propellantless spacecraft. Sunjammer will be the largest solar sail ever flown using photonic pressure (or sunlight) to maneuver in space. Solar Sails have the potential to be a game changer for space exploration as the low-cost, propellantless and highly maneuverable sail craft will enable future satellites and spacecraft to journey throughout the solar system and beyond. The prime contractor, L'Garde Inc., hosted the test deployment at its facility in Tustin, CA, with mission partners NASA and Space Services Inc. present for the event.
The test is a critical milestone for the Sunjammer Mission as lead contractor L'Garde, Inc. demonstrated for the first time the successful coupling and deployment of the sail and deploying beam. The beam pulled a quarter of the sail out to its full open state as it will operate in space. The demonstration was conducted under more stressful conditions since the Earth's gravity and atmosphere make it more difficult to test given the lightweight sail material. "If this test succeeded under these stressing conditions, we certainly anticipate it will work exceedingly well in space" said Nathan Barnes, President of L'Garde.
We are very pleased by these results, as they bring us one step closer to realizing NASA's vision of a propellantless spacecraft and introduce the exciting potential of solar sails to the world," said public outreach partner Space Services CEO, Charles Chafer.
Sunjammer is slated to launch in January 2015 and is NASA's first solar sail voyage to deep space. It will monitor key solar activity as well as carry a public "Cosmic Archive" of human perspectives including names, messages, photographs, and videos contributed by the public for future generations to discover.
ABOUT SPACE SERVICES, INC.
Space Services Holdings is the exclusive commercial infusion partner for Sunjammer solar sail mission, providing opportunities for mission sponsorship; developing and operating the mission website; and conducting - in partnership with NASA and selected partners - an extensive education and public outreach campaign for the mission.
For more than 30 years Houston, Texas-based Space Services Holdings, Inc. and its heritage company Space Services Inc. of America have been recognized as the true pioneers of the commercial space industry. In 1982, Space Services - under the direction of legendary Mercury astronaut Donald K. "Deke" Slayton - conducted the first privately funded launch into space, establishing the business, legal, and regulatory framework for today's commercial industry.
In 1997, SSHI's subsidiary Celestis, Inc. conducted the first ever Memorial Spaceflight, launching a symbolic portion of the cremated remains of Star Trek creator Gene Roddenberry, 60s icon Timothy Leary, and 22 others from around the globe into Earth orbit. Since then Celestis has conducted 10 additional Memorial Spaceflight missions, and placing more than 1000 flight capsules - including Mercury astronaut L. Gordon Cooper, and Star Trek actor James Doohan - into outer space. In 1999 NASA asked Celestis to assist them in honoring Dr. Eugene Shoemaker by making him the first person "buried" on the moon on the Lunar Prospector mission.
Today, SSHI is developing commercial space weather technologies and systems to deliver timely, accurate forecasts and warnings for solar storms. Through a series of contracts funded by the National Oceanic and Atmospheric Administration (NOAA) and its own resources, SSHI has created, and is executing, a focused business plan to meet global space weather data and information needs.
L'Garde aims to be a world leader in the development of inflatable and deployable structures for terrestrial and space applications. L'Garde is focused on providing agile and responsive research and development services to its customers.
L'Garde was founded in 1971 in Orange County, CA to support ballistic missile defense through the development and manufacture of inflatable targets and decoy systems. Since that time L'Garde has developed a wealth of knowledge about deployable space systems that include targets and countermeasures, deployable space antennas, in-space propulsion, deployable space structures, and deployable terrestrial systems. L'Garde has placed more than 150 objects in space.
L'Garde's capabilities embrace deployable antennas, space propulsion, space structures, and missile defense targets and countermeasures.
With the Sunjammer Solar Sail Technology Demonstration Mission (TDM), L'Garde will advance the state of the art of solar sailing. The end goal of this mission is the deployment, flight, and navigation of a mission capable solar sail to demonstrably prove the efficacy of solar sails. This proposed mission will definitively advance the technology of solar sailing for use by future mission planners.
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With this Solar Sail Technology Demonstration Mission (TDM), L’Garde will advance the state of the art of solar sailing.  The end goal of this mission is the deployment, flight, and navigation of a mission capable solar sail to demonstrably prove the efficacy of solar sails.  This proposed mission will definitively advance the technology of solar sailing for use by future mission planners.  Solar sails offer many potential game-changing mission capabilities including the following:
Debris collection and removal from orbit.  Debris can be captured and removed from orbit over a period of years using the small solar-sail thrust.
De-orbit of spent satellites.  Solar sails can be integrated into satellite payloads so that the satellite can be de-orbited at the end of its mission.
Creating pseudo-Lagrange points by cancelling some solar gravitational pull with the sails.  As an example, the GeoStorm project considers locating solar storm warning satellites three times further from the Earth increasing warning time from 15 minutes to 45 minutes.
Providing synchronous satellites at non-equatorial latitudes, such as the “pole-sitter” project.  This allows the northern and southern latitudes to gain the advantages of synchronous satellites.
Providing deep space propulsion.  Payloads free of the Earth’s pull can be accelerated to the other planets, or out of the solar system, such as those proposed for Project Encounter.
However, without a definitive demonstration of a mission capable solar sail the technology is relegated to the realms of conceptual design.  This TDM aims to boost the Technology Readiness Level (TRL) of the L’Garde solar sail from ~6 to ~9.  The four main objectives of the mission are:
Demonstrate segmented deployment of a solar sail with ~4X the area of that vacuum tested at Plum Brook, “cookie cut” from the center of a much larger sail.
Demonstrate attitude control plus passive stability and trim using beam-tip vanes.
Execute a navigation sequence with mission-capable accuracy.
Fly to and Maintain Position at L1 and pole sitter positions 
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Quelle:Space Services Holdings, Inc
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Update: 21.12.2013
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A promising approach for deorbiting retired spacecraft

Images courtesy of the Surrey Space Centre

When satellites reach the end of their working lives, they may continue to orbit in a dormant state for many decades. In a project funded by ESA, Surrey University (UK) has developed a new technique for deorbiting ageing satellites in a safe manner.

By unfurling an ultra-lightweight “gossamer sail” to increase aerodynamic drag, a deorbiting satellite more quickly leaves Low Earth Orbit (LEO) and disintegrates in the Earth’s atmosphere, reducing the risk of catastrophic collisions and helping to maintain a sustainable space environment for future generations.

When not in use, the Gossamer Deorbit Sail is extremely compact; its dimensions are 15x15x25cm and it weighs just 2kg. Upon deployment, it expands to 5x5m, which is large enough to bring down a satellite of up to seven hundred kilos in weight. The system consists of a set of extremely lightweight carbon-fibre booms supporting a sail made from 7μm thick aluminized Kapton membrane with rip-stops and a telescopic deployment mechanism. 
 
The sail was developed at the University’s Surrey Space Centre, with funding provided through ESA’s ARTES 5.1 program.  It has been subjected to rigorous testing, including thermal, vibration, and vacuum tests, and the team hopes to see it deployed in a mission by the end of 2014 by including it as part of another mission. Once the small demonstration satellite is in orbit, the sail will be deployed for testing. The initial tests taking 2-3 weeks will demonstrate solar sailing propulsion. After this, the sail will be rotated to increase the effect of atmospheric drag and so deorbit the test satellite. At an altitude of 600 km, there is enough atmosphere to cause fairly rapid re-entry and it should disintegrate in a mere 2 to 12 months.
 
Under the European Code of Conduct for Space Debris Mitigation, published in 2008, ESA has committed itself to freeing up orbits within 25 years. However, a dormant satellite at an altitude of 750km could easily remain in orbit for a century or longer, forming an obstacle to launching new satellites in that same orbit as well as contributing to the problem of “junk” in space. 
 
In LEO, there is still sufficient atmosphere to generate the needed drag using the sail.  Even with the sail, it could still take many years for the spacecraft to re-enter and disintegrate. But it would be much more mass-efficient than carrying extra propellant, which would be some ten times heavier.
  
For satellites in orbits above 750km, the sail could potentially make use of solar radiation pressure to perform the necessary end-of-life manoeuvres with the help of an attitude control system.
 
If a deorbit sail is included in future launches, this would ensure that decommissioned satellites can be retired well within the 25-year deadline. In due time, it could also be deployed for other clean-up activities, such as any deorbiting adapter which is jettisoned in the course of launching multiple payloads.
 
Professor Vaios Lappas from the University of Surrey commented: “We are delighted to have completed the successful design, manufacture and testing of ESA’s Gossamer Deorbiter, the first of its kind internationally.”
 
“The project has been able to show that the design of a low cost and robust end-of- life deorbiting system not only is possible, but it can also lead to tangible products with a strong commercial interest,” Lappas said.

Dr. Sven Erb, ESA Technical Officer added, “The impressive mass-efficiency and atmospheric effectiveness that Surrey Space Centre has achieved for the Deorbit Sail device will be key for its success in commercial space. The device will be an important step forward in ensuring sustainable exploitation of space in the future.”

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Quelle: ESA

 

 
   


Tags: Sunjammer World’s Largest Solar Sail Propellantless Space Technology Completes Successful Test 

4563 Views

Samstag, 21. Dezember 2013 - 15:34 Uhr

Luftfahrt - Sikorsky erhält Auftrag zum Bau von experimentellen Senkrechtstarter

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Sikorsky is one step closer to bringing its “unmanned rotor blown wing concept” aircraft to reality.

The Stratford, Connecticut-based helicopter manufacturer has been awarded a $14.4 million contract by the US Defense Advanced Research Projects Agency (DARPA) to develop a preliminary design for a “vertical take-off and landing experimental aircraft,” DARPA’s so-called VTOL X-Plane.

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Sikorsky's "unmanned rotor blown wing concept" aircraft. Sikorsky

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The contract covers the first phase of a 52-month, $130 million project to develop a 4,540-5,440kg (10,000-12,000lb) experimental vertical lift aircraft that that can fly at sustained speeds of between 300-400kt, says DARPA.

That’s roughly double the speed of current-generation vertical lift aircraft, which typically max out around 170kt due to the aerodynamic phenomenon of retreating blade stall, the agency notes.

The VTOL X-Plane must also have improved hover and cruise efficiencies and be able to carry a useful load weighing at least 40% of its gross weight and a payload weighing at least 15.5% of gross weight, according to DARPA documents.

“The primary technical objectives of the VTOL X-Plane program are to demonstrate radical improvements in flight speeds, hover efficiency and cruise efficiency of VTOL aircraft, and to demonstrate the ability to perform useful work throughout the flight envelope,” according to the agency.

Sikorsky thinks its unmanned rotor blown wing concept aircraft can fit the bill.

The company declines to discuss details of the aircraft, but the media release says it integrates “fixed wing aerodynamics and advanced rotor control to provide a low complexity configuration capable of meeting the challenging DARPA program goals.”

The aircraft, which the company expects will first fly in the fourth quarter of 2017, is being designed by the Sikorsky Innovations division in Fort Worth, Texas, in partnership with Lockheed Martin’s Skunk Works unit.

DARPA says it intends to issue “multiple” contract awards for phase one, which has a budget of $47 million and begins with a six-month conceptual design effort.

During that period, companies will study and evaluate technology, identify and select propulsion systems, define the aircraft’s layout and estimate its size, weight and fuel and electrical requirements.

Companies are expected to conduct a conceptual design review before the end of the six-month period, DARPA says.

Phase one then moves to a 16-month period for conducting preliminary designs, maturing technology and identifying and reducing risks.

Before the end of phase one, DARPA says it expects to solicit proposals for phase two and three from phase one providers.

During the 18-month phase two, companies will mature their systems, design aircraft structures and control surfaces and analyze flight characteristics, says DARPA.

Phase three will last 12 months and will include ground and flight tests, according to the agency.

Quelle: Flightglobal


3166 Views

Samstag, 21. Dezember 2013 - 09:29 Uhr

Mars-Curiosity-Chroniken - Curiosity Rad beschädigt!

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A photograph taken by Curiosity's robotic arm-mounted Mars Hand Lens Imager (MAHLI) on Dec. 20 (Sol 488) shows marked wear and tear on the rover's front left wheel. Punctures in the rover's thin aluminum are highlighted by the arrows.

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n May, Discovery News reported the dramatic signs of wear and tear on Mars rover Curiosity’s wheels. The aircraft-grade aluminum material appeared scratched, dented, even punctured.

At the time, lead rover driver Matt Heverly said that the damage was to be expected. “The ‘skin’ of the wheel is only 0.75mm thick and we expect dents, dings, and even a few holes due to the wheels interacting with the rocks,” he said via email. Despite the assurances that the holes were just a part of Curiosity’s mission, there seems to be increasing concern for the wheels’ worsening condition after the one-ton robot rolled over some craggy terrain.

 

In an upcoming driving activity for Curiosity, rover drivers will command Curiosity to rove across a relatively smooth area of the Martian surface. Throughout the drive, Curiosity’s powerful MAHLI camera, which is mounted to the end of the rover’s robotic arm, will monitor the condition of the wheels.

“We want to take a full inventory of the condition of the wheels,” said Jim Erickson, project manager for the NASA Mars Science Laboratory at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “Dents and holes were anticipated, but the amount of wear appears to have accelerated in the past month or so. It appears to be correlated with driving over rougher terrain. The wheels can sustain significant damage without impairing the rover’s ability to drive. However, we would like to understand the impact that this terrain type has on the wheels, to help with planning future drives.”

 

Curiosity has recent endured some challenging terrain laced with sharp rocks protruding from the ground. These rocks have caused some perforations in the six wheels, sometimes peeling back flaps of cut aluminum.

Depending on the outcome of the upcoming monitoring session, mission managers may need to better factor in the roughness of terrain of Curiosity’s future drives, re-routing if necessary.

Since landing inside Gale Crater in August 2012, Curiosity has driven a little under three miles, so damage to the wheels was going to be inevitable. But the rover hasn’t even begun the tough drive up the slopes of Aeolis Mons (Mount Sharp), a 5.5 kilometer-high mountain in the center of the crater — the ultimate goal of the mission to piece together the habitability puzzle of the red planet. There will undoubtedly be some tense times ahead for the rover team, especially if the rough terrain continues to chew up the six aluminum wheels.

Quelle: D-News

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Rocky Mars Ground Where Curiosity Has Been Driving (Stereo)

NASA's Mars rover Curiosity captured this stereo view using its Navigation Camera (Navcam) after a 17-foot (5.3 meter) drive on 477th Martian day, or sol, of the rover's work on Mars (Dec. 8, 2013). The scene appears three dimensional when viewed through red-blue glasses with the red lens on the left. It spans 360 degrees, with south at the center and north at both ends.

This drive brought the mission's total driving distance to 3.86 miles (4.61 kilometers). The rock-studded terrain Curiosity has traversed since October 2013 appears to have accelerated the pace of wear and tear on the rover's wheels. Future drives may be charted to cross smoother ground where available.

This seam-corrected mosaic is presented in a cylindrical-perspective projection.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover.

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Curiosity Team Upgrades Software, Checks Wheel Wear

December 20, 2013

Mars Science Laboratory Mission Status Report

The team operating NASA's Mars rover Curiosity has completed a software upgrade on the vehicle and is next planning a check of wear and tear on the rover's wheels.

"Curiosity is now operating on version 11 of its flight software," said Jim Erickson of NASA's Jet Propulsion Laboratory, project manager for the NASA Mars Science Laboratory Project, which operates Curiosity.

This is the third upgrade version since Curiosity's landing on Mars16 months ago. Completing the switch from version 10 took about a week. An earlier switch to version 11 prompted an unintended reboot on Nov. 7 and a return to version 10, but the latest transition went smoothly.

These upgrades allow continued advances in the rover's capabilities. For example, version 11 brings expanded capability for using the Curiosity's robotic arm while the vehicle is on slopes. It also improves flexibility for storing information overnight to use in resuming autonomous driving on a second day.

An upcoming activity will be driving to a relatively smooth patch of ground to take a set of images of Curiosity's aluminum wheels, using the Mars Hand Lens Imager (MAHLI) camera at the end of the rover's arm.

"We want to take a full inventory of the condition of the wheels," Erickson said. "Dents and holes were anticipated, but the amount of wear appears to have accelerated in the past month or so. It appears to be correlated with driving over rougher terrain. The wheels can sustain significant damage without impairing the rover's ability to drive. However, we would like to understand the impact that this terrain type has on the wheels, to help with planning future drives."

Curiosity's recent driving has crossed an area that has numerous sharp rocks embedded in the ground. Routes to future destinations for the mission may be charted to lessen the amount of travel over such rough terrain, compared to smoother ground nearby.

NASA's Mars Science Laboratory Project is using Curiosity inside Gale Crater to assess ancient habitable environments and major changes in Martian environmental conditions. JPL, a division of the California Institute of Technology in Pasadena, built the rover and manages the project for NASA's Science Mission Directorate in Washington.

Quelle: NASA


Tags: Curiositys Wheel Damage Accelerated 

2864 Views

Freitag, 20. Dezember 2013 - 23:46 Uhr

Astronomie - Tages-Bolide über Churchdown England

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Revealed: Mystery 'bright object' in skies above Churchdown was fireball meteor


The mystery of the 'bright object' seen falling out of the sky over Churchdown has been solved - it seems that it was a fireball meteor.

Scores of Gloucestershire people have reported seeing the object. The most recent sighting was at 8am yesterday but there have been reports of other meteor sighting earlier in the month.

It is also thought 2014 is going to a bumper year for meteor attacks.

One eyewitness Gill Brimfield said: "My husband and I were driving home from Evesham last Wednesday evening and spotted a really big bright light in the sky, which was not a star. It was not moving and by the time we got to Churchdown it was still there.

"For the next few days coming home from work, along the Tewkesbury Road and then Staverton, to Churchdown, the same light was there. We were wondering what it was but I haven’t seen it since. It was definitely not an aeroplane, too big for that and it never moved and was all lit up, but not something I have seen before."

Another eyewitness Maggie Bell said: "I spotted this going home two weeks ago. This was near Churchdown Hill or that’s what it looked like. It didn’t move from its spot for the duration of my journey home, was too low for a star and too high for the Churchdown Hill light. I am really intrigued."

Quelle: Citizen Gloucester




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