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Sonntag, 8. Januar 2017 - 19:30 Uhr

Astronomie - Beweis für supermassive Schwarze Löcher in benachbarten Galaxien gefunden

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Evidence of supermassive black holes found in neighbouring galaxies

Astronomers find evidence of black holes concealed behind clouds of gas and dust in two of Earth’s galactic neighbours

 
IC 3639 obscured with active galactic nucleus.
 IC 3639 obscured with active galactic nucleus. Scientists now believe most large galaxies have supermassive black holes at their cores, but many are hidden from view. Photograph: Durham University/PA

Monster black holes may be lurking behind smokescreens in our cosmic backyard, say scientists. But they are still millions of light years away and much too distant to pose any threat to Earth. 

Astronomers have discovered evidence of supermassive black holes at the centre of two of our galactic neighbours. One, the galaxy NGC 1448, is “just” 38m light years from our own body of stars, the Milky Way. The other, IC 3639, is 170m light years away. Both are classified as “active” galaxies that emit intense levels of radiation. 

In each case the powerful black hole is concealed behind clouds of gas and dust. Scientists now believe most large galaxies have supermassive black holes at their cores, but many are hidden from view. 

Black holes are places where gravity is so powerful it traps light and distorts time and space. They can only be detected from the last-gasp emissions of radiation from objects falling into them.

The hidden black holes were spotted by Nasa’s Nustar (nuclear spectroscopic telescope array) orbiting observatory. 

British researchers from the universities of Durham and Southampton conducted analysis of the Nustar data. Ady Annuar, of the University of Durham’s centre for extragalactic astronomy, said: “These black holes are relatively close to the Milky Way, but they have remained hidden from us until now. They’re like monsters hiding under your bed.

“Their recent discoveries certainly call out the question of how many other supermassive black holes we are still missing, even in our nearby universe.”

Daniel Stern, project scientist for Nustar at Nasa’s jet propulsion laboratory, said: “It is exciting to use the power of Nustar to get important, unique information on these beasts, even in our cosmic backyard where they can be studied in detail.”

Quelle: theguardian


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Sonntag, 8. Januar 2017 - 17:00 Uhr

Raumfahrt-History - 1985 Space-Shuttle STS-51C Discovery Mission

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STS-51C
 
 

Mission: Department of Defense
Space Shuttle: Discovery
Launch Pad: 39A 
Launch Weight: 250,891 pounds
Launched: January 24, 1985 at 2:50:00 p.m. EST
Landing Site: Kennedy Space Center, Florida
Landing: January 27, 1985 at 4:23:23 p.m. EST
Landing Weight: Classified
Runway: 15 
Rollout Distance: 7,352 feet
Rollout Time: 50 seconds
Revolution: 49
Mission Duration: 3 days, 1 hour, 33 minutes, 23 seconds
Orbit Altitude: 220 nautical miles
Orbit Inclination: 28.5 degrees
Miles Traveled: 1.3 million 

Crew Members

                   STS-51C Crew Photo

Image above: STS-51C Crew photo with Commander Thomas K. Mattingly, II, Pilot Loren J. Shriver, Mission Specialists Ellison S. OnizukaJames F. Buchli and Payload Specialist Gary E. Payton. Image Credit: NASA 

Launch Highlights

STS-51C Mission PatchThe launch scheduled for January 23 was scrubbed due to freezing weather conditions. (Orbiter Challenger was scheduled for Mission 51-C but thermal tile problems forced the substitution of Discovery.)

The countdown phase was completed satisfactorily, however, two minor orbiter problems were noted during that period. The first occurred during the T-3 hour hold and involved a force fight in the right inboard elevon actuator between channel 4 and channels 1, 2, and 3. The condition corrected itself within 22 seconds after the Auxiliary Power Unit (APU) start up at T-5 minutes. A similar problem with the same channels in the same actuator occurred on STS 41-D (the first flight of this vehicle).

The second problem that was noted during the countdown phase was the high helium concentration in the orbiter mid-body. A pressure decay test showed no significant system leakage. The high helium concentration disappeared when the main propulsion system (MPS) gaseous helium system was pressurized to the flight level.

System operations were all nominal during the ascent phase. Solid rocket booster (SRB) motor performance was near the predicted levels and well within the allowed envelopes. The external tank and MPS performance was excellent with main engine cutoff (MECO) near the predicted time.

At external tank separation, the backup flight system (BFS) did not automatically proceed to major mode 104. The crew performed the necessary manual procedures, and the BFS operated satisfactorily until the deorbit maneuver when the BFS time for deorbit maneuver ignition was 8 seconds late. However, the BFS operated satisfactorily for entry.

Mission Highlights

This was the first mission dedicated to the Department of Defense. The U.S. Air Force Inertial Upper Stage (IUS) booster was deployed and met the mission objectives.

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Commander Ken Mattingly (right) had already announced his retirement from NASA to return to the U.S. Navy by the time Mission 51C took place. By his own admission, only the first shuttle mission from Vandenberg Air Force Base might have encouraged him to stay. A year later, the loss of Challenger sounded the death-knell for shuttle flights from the West Coast. Photo Credit: NASA

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Frams von STS-51C Discovery Mission NASA-Video:

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Quelle: NASA

 


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Sonntag, 8. Januar 2017 - 10:00 Uhr

Raumfahrt - Das Hauptwerkzeug der Astronauten des 21. Jahrhunderts: Bohrer

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The pistol-grip tool slung on an astronaut's spacesuit as he works on the Hubble Space Telescope.
 

NASA conducted a spacewalk today to replace the International Space Station's batteries. Twelve aging nickel-hydrogen batteries will be replaced with six new lithium-ion batteries, a mission that will take two spacewalks. In today's, astronauts Shane Kimbrough and Peggy Whitson will be at work for six and a half hours.

If you watched the spacewalk, then you saw the astronauts using NASA's "pistol-grip tool," a cordless power drill designed for use in space. Built by Swales Aerospace Inc., it is the staple of NASA's space tool arsenal. The pistol-grip tool helped build the International Space Station as well as the Hubble Space Telescope, and it's been at all the repairs along the way. Needless to say, NASA's cordless power drill needs to do a few things that the one in your garage can't.

 
 
Astronaut Shane Kimbrough with the pistol-grip tool, preparing to replace an adaptor plate for a lithium-ion battery on the International Space Station, January 6, 2017.

For one thing, it has to withstand quick fluctuations in temperature by hundreds of degrees. The ISS orbits the Earth every 90 minutes, 16 times per day, passing in and out of the sunlight each time it does. In such an environment, liquid lubricants would cause a power tool to seize, so the pistol-grip tool uses dry film lubricants that evaporate at room temperature. And it's incredibly light. The pistol-grip tool is made of Lexan, a glass-infused plastic, and wrapped in aluminum tape.

"The astronauts have limited mobility in their space suits, so one of the things they have to cope with is hand fatigue due to constantly fighting against the pressure of the suit," said Jill McGuire, tools manager for the HST Program in a NASA article about tool design. "Therefore, we need to build larger tools that have specially designed handles and triggers that make it easier for them to work in their suits."

 

The pistol-grip tool functions much in the same way a regular power drill does, with a battery that slots into the handle, only it has a large information screen where astronauts can change the speed and torque (between less than 1 and 38 foot-pounds, and between 5 and 60 rpm). The drill is designed to turn slowly—no need to rush things in space—but still produce enough torque to undo bolts and fasteners.

For one of the most famous spacewalks, the mission to replace the HST's power supply after a critical failure, NASA engineers needed to design a new drill. The components that needed to be replaced, similar to a computer board, were behind a panel that was not designed to be taken off by spacewalking astronauts.

 
 
An engineer at NASA's Goddard Space Flight Center works with a mini power tool and fastener capture plate designed to work on NASA's Hubble Space Telescope in orbit.

They needed something that could turn faster than the pistol-grip tool so the 111 fasteners could be taken off quickly enough to remove the panel, and they needed something small enough to work with in a confined space. The result was a mini power drill that took five years to design. It could spin at 210 rpm and had an attached "capture plate" to collect all the fasteners without letting them float into space.

Most of the other tools NASA uses are specifically designed for one task, but the pistol-grip tool remains the primary tool used by spacewalkers in the 21st century. Perhaps in the future, robots will perform these tasks with tools affixed to their arms, but for now, the best solution for a broken space station is an astronaut and his trusty space drill.

Quelle: PM


751 Views

Samstag, 7. Januar 2017 - 21:45 Uhr

Astronomie - China will Gravitationswellen-Teleskop in Tibet errichten

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LHASA, Jan. 7 China is working to set up the world's highest altitude gravitational wave telescopes in Tibet Autonomous Region to detect the faintest echoes resonating from the universe, which may reveal more about the Big Bang.

Construction has started for the first telescope, code-named Ngari No.1, 30 km south of Shiquanhe Town in Ngari Prefecture, said Yao Yongqiang, chief researcher with the National Astronomical Observatories of the Chinese Academy of Sciences.

The telescope, located 5,250 meters above sea level, will detect and gather precise data on primordial gravitational waves in the Northern Hemisphere. It is expected to be operational by 2021.

Yao said the second phase involves a series of telescopes, code-named Ngari No. 2, to be located about 6,000 meters above sea level. He did not give a time frame for construction of Ngari No. 2.

The budget for the two-phase Ngari gravitational wave observatory is an estimated 130 million yuan (18.8 million U.S. dollars). The project was initiated by the Institute of High Energy Physics, National Astronomical Observatories, and Shanghai Institute of Microsystem and Information Technology, among others.

Ngari, with its high altitude, clear sky, and minimal human activity, is said to be one of the world's best spots to detect tiny twists in cosmic light.

Yao said the Ngari observatory will be among the world's top primordial gravitational wave observation bases, alongside the South Pole Telescope and the facility in Chile's Atacama Desert.

Gravitational waves were first proposed by Albert Einstein's theory of general relativity 100 years ago, but it wasn't until 2016 that scientists with the Laser Interferometer Gravitational-Wave Observatory announced proof of the waves' existence, spurring fresh research interest among the world's scientists.

China has announced its own gravitational wave research plans, which include the launch of satellites and setting up FAST, a 500-meter aperture spherical radio telescope in southwest China's Guizhou Province.

Quelle: Xinhua


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Samstag, 7. Januar 2017 - 21:00 Uhr

Luftfahrt - Früher Flug von Ost bei Sonnenaufgang

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Aufnahmen von Airliner über Wolken am Osthorizont bei Sonnenaufgang:

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Fotos: ©-hjkc

 


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Samstag, 7. Januar 2017 - 19:30 Uhr

Raumfahrt - Mars-Curiosity-Chroniken - Curiosity-News Sol 1502-1572

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1525 (2016-11-20 01:29:44 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1526 (2016-11-21 02:30:06 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1529 (2016-11-24 04:31:57 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1531 (2016-11-26 05:10:09 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1533 (2016-11-28 07:43:46 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1535 (2016-11-30 12:14:45 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1536 (2016-12-01 09:20:29 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1537 (2016-12-02 05:59:21 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1539 (2016-12-04 10:11:26 UTC).

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This image was taken by Rear Hazcam: Right B (RHAZ_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 1540 (2016-12-05 11:25:24 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1542 (2016-12-07 12:47:43 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1544 (2016-12-09 14:02:37 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1544 (2016-12-09 17:20:07 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1545 (2016-12-10 15:44:01 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1547 (2016-12-12 14:09:10 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1552 (2016-12-17 18:23:29 UTC).

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This image was taken by ChemCam: Remote Micro-Imager (CHEMCAM_RMI) onboard NASA's Mars rover Curiosity on Sol 1552 (2016-12-17 17:59:43 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 1553 (2016-12-18 19:25:52 UTC).

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This image was taken by Front Hazcam: Right B (FHAZ_RIGHT_B) onboard NASA's Mars rover Curiosity on Sol 1557 (2016-12-22 22:12:45 UTC).

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 1559 (2016-12-24 22:52:46 UTC). 

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1565 (2016-12-31 02:48:37 UTC).

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NASA's Mars rover Curiosity acquired this image using its Mars Hand Lens Imager (MAHLI), located on the turret at the end of the rover's robotic arm, on January 1, 2017, Sol 1566 of the Mars Science Laboratory Mission, at 07:48:50 UTC.

When this image was obtained, the focus motor count position was 14004. This number indicates the internal position of the MAHLI lens at the time the image was acquired. This count also tells whether the dust cover was open or closed. Values between 0 and 6000 mean the dust cover was closed; values between 12500 and 16000 occur when the cover is open. For close-up images, the motor count can in some cases be used to estimate the distance between the MAHLI lens and target. For example, in-focus images obtained with the dust cover open for which the lens was 2.5 cm from the target have a motor count near 15270. If the lens is 5 cm from the target, the motor count is near 14360; if 7 cm, 13980; 10 cm, 13635; 15 cm, 13325; 20 cm, 13155; 25 cm, 13050; 30 cm, 12970. These correspond to image scales, in micrometers per pixel, of about 16, 25, 32, 42, 60, 77, 95, and 113.

Most images acquired by MAHLI in daylight use the sun as an illumination source. However, in some cases, MAHLI's two groups of white light LEDs and one group of longwave ultraviolet (UV) LEDs might be used to illuminate targets. When Curiosity acquired this image, the group 1 white light LEDs were off, the group 2 white light LEDs were off, and the ultraviolet (UV) LEDS were off. 

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1566 (2017-01-01 04:34:16 UTC).

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This image was taken by Mastcam: Right (MAST_RIGHT) onboard NASA's Mars rover Curiosity on Sol 1568 (2017-01-03 05:54:30 UTC).

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NASA's Mars rover Curiosity acquired this image using its Mars Hand Lens Imager (MAHLI), located on the turret at the end of the rover's robotic arm, on January 4, 2017, Sol 1569 of the Mars Science Laboratory Mission, at 10:23:17 UTC.

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Using an onboard focusing process, the Mars Hand Lens Imager (MAHLI) aboard NASA's Mars rover Curiosity created this product by merging two to eight images previously taken by the MAHLI, located on the turret at the end of the rover's robotic arm.

Curiosity performed the merge on January 5, 2017, Sol 1570 of the Mars Science Laboratory Mission, at 13:36:05 UTC. The focus motor count position was 13269. This number indicates the lens position of the first image that was merged.

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This image was taken by Navcam: Left B (NAV_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 1570 (2017-01-05 10:25:24 UTC).

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This image was taken by Mastcam: Left (MAST_LEFT) onboard NASA's Mars rover Curiosity on Sol 1571 (2017-01-06 09:36:56 UTC).

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This image was taken by Front Hazcam: Left B (FHAZ_LEFT_B) onboard NASA's Mars rover Curiosity on Sol 1572 (2017-01-07 11:19:52 UTC).

Quelle: NASA

 

 

 


678 Views

Samstag, 7. Januar 2017 - 15:00 Uhr

Raumfahrt-History - 1984 Space-Shuttle STS-51A Discovery Mission

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STS-51A
 
 

Mission: TELESAT-H, Canadian communications satellite, SYNCOM IV-1 defense communications satellite
Space Shuttle: Discovery
Launch Pad: 39A 
Launch Weight: 263,324 pounds
Launched: November 8, 1984 at 7:15:00 a.m. EST
Landing Site: Kennedy Space Center, Florida
Landing: November 16, 1984 at 6:59:56 a.m. EST
Landing Weight: 207,505 pounds
Runway: 15 
Rollout Distance: 9,454 feet
Rollout Time: 58 seconds
Revolution: 127
Mission Duration: 7 days, 23 hours, 44 minutes, 56 seconds
Orbit Altitude: 185 nautical miles
Orbit Inclination: 28.5 degrees
Miles Traveled: 3.3 million 

Crew Members

                   STS-51A Crew Photo

Image above: STS-51A Crew photo with Commander Frederick H. Hauck, Pilot David M. Walker, Mission Specialists Anna L. FisherDale A. Gardner and Joseph P. Allen. Image Credit: NASA 

Mission Highlights

STS-51A Mission PatchThe Canadian communications satellite TELESAT-H (ANIK), attached to Payload Assist Module-D (PAM-D) was deployed into geosynchronous orbit on flight day two. On the third day, the defense communications satellite SYNCOM IV-I (also known as LEASAT-1) was deployed. Allen and Gardner, wearing jet-propelled manned maneuvering units, retrieved two malfunctioning satellites: PALAPA-B2 and WESTAR-VI, both of these satellites were deployed on Mission 41-B. Fisher operated the remote manipulator system, grappling satellites and depositing them in the payload bay. Middeck payloads for this mission were: Diffusive Mixing of Organic Solutions (DMOS), and Radiation Monitoring Equipment (RME).

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The crew assigned to the STS-51A mission included Frederick H. Hauck, commander,who is seated to the right. Standing, left to right, are Dale A. Gardner, mission specialist; David M. Walker, pilot; and mission specialists Anna L. Fisher, and Joseph P. Allen. Launched aboard the Space Shuttle Discovery on November 8, 1984 at 7:15:00 am (EST), the STS-51A mission deployed the Canadian communications satellite TELLESAT-H (ANIK), and the defense communications satellite SYCOM IV-1 (also known as LEASAT-1). In addition, 2 malfunctioning satellites were retrieved: the PALAPA-B2 and the WESTAR-VI.

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Aerial view of the launch of STS 51-A shuttle Discovery
Credit: NASA

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Astronaut Dale Gardner using MMU to travel to Westar VI satellite
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Astronauts Gardner and Allen during loading of Palapa B-2 in payload bay
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Astronaut Dale Gardner holds up for sale sign after EVA
Credit: NASA

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Astronaut Anna Fisher poses near a 3M experiment involving the DMOS
Credit: NASA

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Frams von STS-51A Discovery Mission NASA-Video:

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Quelle: NASA

 


684 Views

Samstag, 7. Januar 2017 - 11:05 Uhr

Astronomie - MRO Blick Richtung Erde

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Your Home Planet, as Seen From Mars

Earth and Its Moon, as Seen From Mars

From the most powerful telescope orbiting Mars comes a new view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon.

 

The view is available online at:

 

http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA21260

 

The image combines two separate exposures taken on Nov. 20, 2016, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. The images were taken to calibrate HiRISE data, since the reflectance of the moon's Earth-facing side is well known. For presentation, the exposures were processed separately to optimize detail visible on both Earth and the moon. The moon is much darker than Earth and would barely be visible if shown at the same brightness scale as Earth.

 

The combined view retains the correct positions and sizes of the two bodies relative to each other. The distance between Earth and the moon is about 30 times the diameter of Earth. Earth and the moon appear closer than they actually are in this image because the observation was planned for a time at which the moon was almost directly behind Earth, from Mars' point of view, to see the Earth-facing side of the moon. 

 

In the image, the reddish feature near the middle of the face of Earth is Australia. When the component images were taken, Mars was about 127 million miles (205 million kilometers) from Earth.

 

With HiRISE and five other instruments, the Mars Reconnaissance Orbiter has been investigating Mars since 2006.

Quelle: NASA


773 Views

Samstag, 7. Januar 2017 - 11:00 Uhr

Astronomie - Hubble Detects ‘Exocomets’ Taking the Plunge Into a Young Star

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Interstellar forecast for a nearby star: Raining comets! NASA’s Hubble Space Telescope has discovered comets plunging onto the star HD 172555, which is a youthful 23 million years old and resides 95 light-years from Earth. 

 

The exocomets — comets outside our solar system — were not directly seen around the star, but their presence was inferred by detecting gas that is likely the vaporized remnants of their icy nuclei.

 

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This illustration shows several comets speeding across a vast protoplanetary disk of gas and dust and heading straight for the youthful, central star. These "kamikaze" comets will eventually plunge into the star and vaporize. The comets are too small to photograph, but their gaseous spectral "fingerprints" on the star's light were detected by NASA's Hubble Space Telescope. The gravitational influence of a suspected Jupiter-sized planet in the foreground may have catapulted the comets into the star. This star, called HD 172555, represents the third extrasolar system where astronomers have detected doomed, wayward comets. The star resides 95 light-years from Earth.
Credits: NASA, ESA, A. Feild and G. Bacon (STScI)

HD 172555 represents the third extrasolar system where astronomers have detected doomed, wayward comets. All of the systems are young, under 40 million years old.

 

The presence of these doomed comets provides circumstantial evidence for “gravitational stirring” by an unseen Jupiter-size planet, where comets deflected by its gravity are catapulted into the star. These events also provide new insights into the past and present activity of comets in our solar system. It’s a mechanism where infalling comets could have transported water to Earth and the other inner planets of our solar system.

 

Astronomers have found similar plunges in our own solar system. Sun-grazing comets routinely fall into our sun.  “Seeing these sun-grazing comets in our solar system and in three extrasolar systems means that this activity may be common in young star systems,” said study leader Carol Grady of Eureka Scientific Inc. in Oakland, California, and NASA's Goddard Spaceflight Center in Greenbelt, Maryland. “This activity at its peak represents a star’s active teenage years. Watching these events gives us insight into what probably went on in the early days of our solar system, when comets were pelting the inner solar system bodies, including Earth. In fact, these star-grazing comets may make life possible, because they carry water and other life-forming elements, such as carbon, to terrestrial planets.”

 

Grady will present her team’s results Jan. 6 at the winter meeting of the American Astronomical Society in Grapevine, Texas.

 

The star is part of the Beta Pictoris Moving Group, a collection of stars born from the same stellar nursery. It is the second group member found to harbor such comets. Beta Pictoris, the group’s namesake, also is feasting on exocomets travelling too close. A young gas-giant planet has been observed in that star’s vast debris disk.

 

The stellar group is important to study because it is the closest collection of young stars to Earth. At least 37.5 percent of the more massive stars in the Beta Pictoris Moving Group either have a directly imaged planet, such as 51 Eridani b in the 51 Eridani system, or infalling star-grazing bodies, or, in the case of Beta Pictoris, both types of objects. The grouping is at about the age that it should be building terrestrial planets, Grady said.

 

A team of French astronomers first discovered exocomets transiting HD 172555 in archival data gathered between 2004 and 2011 by the European Southern Observatory’s HARPS (High Accuracy Radial velocity Planet Searcher) planet-finding spectrograph. A spectrograph divides light into its component colors, allowing astronomers to detect an object’s chemical makeup. The HARPS spectrograph detected the chemical fingerprints of calcium imprinted in the starlight, evidence that comet-like objects were falling into the star. 

 

As a follow-up to that discovery, Grady’s team used Hubble’s Space Telescope Imaging Spectrograph (STIS) and the Cosmic Origins Spectrograph (COS) in 2015 to conduct a spectrographic analysis in ultraviolet light, which allows Hubble to identify the signature of certain elements. Hubble made two observations, separated by six days.

 

Hubble detected silicon and carbon gas in the starlight. The gas was moving at about 360,000 miles per hour across the face of the star. The most likely explanation for the speedy gas is that Hubble is seeing material from comet-like objects that broke apart after streaking across the face of the star.

 

The gaseous debris from the disintegrating comets is vastly dispersed in front of the star. “As transiting features go, this vaporized material is easy to see because it contains very large structures,” Grady said. “This is in marked contrast to trying to find a small transiting exoplanet, where you’re looking for tiny dips in the star’s light.”

 

Hubble gleaned this information because the HD 172555 debris disk surrounding the star is slightly inclined to Hubble’s line of sight, giving the telescope a clear view of comet activity.

 

Grady’s team hopes to use STIS again in follow-up observations to look for oxygen and hydrogen, which would confirm the identity of the disintegrating objects as comets.

 

“Hubble shows that these star-grazers look and move like comets, but until we determine their composition, we cannot confirm they are comets,” Grady said. “We need additional data to establish whether our star-grazers are icy like comets or more rocky like asteroids.”

 

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA Goddard manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington, D.C.

Quelle: NASA


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Samstag, 7. Januar 2017 - 09:00 Uhr

Raumfahrt - Sind wir kolossalen Raumfahrzeugen näher als wir denken

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Stanford torus community concept design. Image: Don Davis

From Battlestar Galactica to the imperial Death Star, the world of fiction is rife with gargantuan spacecraft capable of supporting thousands of residents with their own personal quarters and facilities.

But for real astronauts, spaceflight is not quite so, well, spacious. Take the International Space Station (ISS), which is the largest spacefaring vessel ever built, as well as the most expensive single construction project in human history, costing the US alone around $100 billion. Its first module was launched in November 1998, and its first long-duration crew, consisting of three people, arrived onboard two years later.

With an internal pressurized volume of 32,898 cubic feet, roughly equal to the interior of a Boeing 747, the ISS is a far cry from the cavernous starships we’re used to seeing in science fiction and fantasy. That said, the station and its predecessors are enormously helpful testbeds in the quest to develop even more massive spaceships down the line. Like the Mir space station, which flew from 1986 to 2001, the modules of the ISS were launched separately and assembled in space, like some high-stakes orbital LEGO kit.

Animation depicting assembly sequence of ISS. Video: NASA Johnson/YouTube

The cost of blasting separate components out of Earth’s powerful gravitational grasp is exorbitant, but the microgravity environment into which they are deployed offers considerable advantages for large engineering projects. What better place to construct colossal architectures than outer space, where immensely heavy structures are rendered functionally weightless and easily maneuverable by smaller spacecraft, or human astronauts? Indeed, anyone who has toyed around with the Kerbal Space Program is probably already familiar with the benefits of in situ orbital manufacturing.

Of course, there’s a big difference between throwing together spacecraft in a computer game, and assembling them in real life. Fortunately, the global space community has been steadily working towards achieving the centuries-old dream of big off-Earth structures that can support both robotic and human spaceflight missions.

Just last month, for instance, NASA announced its finalists for the Breakthrough, Innovative and Game-changing (BIG) Idea Challenge, which annually solicits concepts for emerging spaceflight platforms. In 2017, the BIG Challenge is focusing on designing modular spacecraft, powered by solar electric propulsion, that could ferry cargo from low Earth orbit to lunar distant retrograde orbit (LDRO). 

Concept art of potential BIG idea design. Image: Analytical Mechanics Associates

According to Keith Belvin, the principal technologist for structures, materials and nanotechnology at NASA’s Space Technology Mission Directorate—and a judge for the BIG Challenge—LDRO is a particularly useful place to park and assemble large spacecraft because it has a much weaker gravity well relative to low Earth orbit.

“LDRO is about a 6,000 kilometer orbit [around the Moon],” Belvin told me over the phone. “It’s really nice for a lot of reasons. It’s pretty easy to access. It’s pretty easy to leave from. So, that could form a good staging location. If we developed a satellite assembly construction in situ manufacturing servicing capability in this orbit, then we could launch vehicles in pieces, and assemble them in that orbit.” 

LDRO could even function as a service and refueling checkpoint for spacecraft returning from distant locations around the solar system. “Let’s suppose that we go to Phobos [one of Mars’ two moons] or do a Mars-type mission,” Belvin said. “When the vehicle comes back, instead of coming back to Earth and burning up, we would bring it back to LDRO, refurbish it, and use it again for another mission.”

The ability to reuse spacecraft in this way would drastically reduce the cost of robotic deep space exploration, while also spurring the kind of infrastructures crucial for human exploration to more distant worlds like Mars. It will take an enormous amount of money, time, and effort to build these orbital truck-stops, but the back-end payoff of paving a super-roadway in space would be well worth it, according to author and spaceflight advocate Howard Bloom.

“Why move NASA into space highway construction?” Bloom asked in a recent Scientific American article. “Because no one else will do it. And our future in space depends on it. Our future share in a space economy that United Launch Alliance (a joint venture rocket company from Boeing and Lockheed Martin) estimates will be worth $2.7 trillion in 30 years.”

This notion of building cumulatively larger, more robust, and more efficient modular structures in space could lay the groundwork for the kinds of futuristic space communities we’ve grown accustomed to seeing in fiction—like O’Neill cylinders or city-sized starships—even if that process takes decades, or even centuries.

O’Neill cylinder concept design. Image: Rick Guidice/NASA Ames Research Center

In the meantime, there are plenty of other massive spacecraft concepts aimed towards solving problems on our own planet. One of the most prominent is the longstanding dream of building solar power plants in space, where sunlight is abundant and unfiltered by atmospheric interference. Over time, researchers have produced numerous captivating concept designs for space-based solar arrays measuring a kilometer across, or more. These systems could deliver green energy to locations all around the world, while also powering orbital systems or deep space missions. 

There are many hurdles left to clear before this lofty goal can be accomplished, but scientists, including Belvin, think space-based solar power is a technically sound possibility over the near term.

“I think the technology is almost there,” Belvin told me. “There’s a lot of engineering that has to take place to make it efficient and cost-effective. But I think of the Apollo Program, starting in the early 1960s, and that had to be a dream, to go to the Moon. If there’s the money, and the will, you can do a lot in a decade. So, if anybody says: ‘Hey, we’ve got to have an orbiting power system,’ for whatever reason, I think we could do it within a decade.”

It’s exciting to know that the space sector is beginning to close in on these ambitious projects, constrained mainly by funding and resources rather than the technology itself. And while it’s tricky to predict what kind of vessel will overtake the ISS as the largest spacefaring structure in history, the fact that there are so many potential candidates in the works right now is a cause for celebration.

Quelle: Motherboard


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