Het Astronomie Topic #3

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LRO Sees Apollo Landing Sites


^{Apollo 11 lunar module, Eagle.
Image width: 282 meters (about 925 ft.)}

"The LROC team anxiously awaited each image," said LROC principal investigator Mark Robinson of Arizona State University. "We were very interested in getting our first peek at the lunar module descent stages just for the thrill -- and to see how well the cameras had come into focus. Indeed, the images are fantastic and so is the focus."

This photograph shows Apollo 11 astronaut Buzz Aldrin in front of the lunar module. The photo helps provide a scale to the LROC images shown above. Credit: NASA/Neil Armstrong
› Larger image Although these pictures provide a reminder of past NASA exploration, LRO's primary focus is on paving the way for the future. By returning detailed lunar data, the mission will help NASA identify safe landing sites for future explorers, locate potential resources, describe the moon's radiation environment and demonstrate new technologies.

"Not only do these images reveal the great accomplishments of Apollo, they also show us that lunar exploration continues," said LRO project scientist Richard Vondrak of NASA's Goddard Space Flight Center in Greenbelt, Md. "They demonstrate how LRO will be used to identify the best destinations for the next journeys to the moon."

The spacecraft's current elliptical orbit resulted in image resolutions that were slightly different for each site but were all around four feet per pixel. Because the deck of the descent stage is about 12 feet in diameter, the Apollo relics themselves fill an area of about nine pixels. However, because the sun was low to the horizon when the images were made, even subtle variations in topography create long shadows. Standing slightly more than ten feet above the surface, each Apollo descent stage creates a distinct shadow that fills roughly 20 pixels.

The image of the Apollo 14 landing site had a particularly desirable lighting condition that allowed visibility of additional details. The Apollo Lunar Surface Experiment Package, a set of scientific instruments placed by the astronauts at the landing site, is discernable, as are the faint trails between the module and instrument package left by the astronauts' footprints.

Launched on June 18, LRO carries seven scientific instruments, all of which are currently undergoing calibration and testing prior to the spacecraft reaching its primary mission orbit. The LROC instrument comprises three cameras -- two high-resolution Narrow Angle Cameras and one lower resolution Wide Angle Camera. LRO will be directed into its primary mission orbit in August, a nearly-circular orbit about 31 miles above the lunar surface.

Goddard built and manages LRO, a NASA mission with international participation from the Institute for Space Research in Moscow. Russia provided the neutron detector aboard the spacecraft.

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Op dinsdag 21 juli 2009 15:29 schreef Frutsel het volgende:
schaamteloze tvp

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Op woensdag 5 augustus 2009 08:05 schreef sararaats het volgende:
jeeeeeeeeeeeej, de Perseïden komen er weer aan.

hopelijk is het goed weer

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The Perseids are Coming
July 31, 2009: Earth is entering a stream of dusty debris from Comet Swift-Tuttle, the source of the annual Perseid meteor shower. Although the shower won't peak until August 11th and 12th, the show is already getting underway.

Brian Emfinger of Ozark, Arkansas, photographed this early Perseid just after midnight on Sunday, July 26th:


"I used an off-the-shelf digital camera to capture this fireball and its smoky trail," says Emfinger. "It was a bright one!"

Don't get too excited, cautions Bill Cooke of NASA's Meteoroid Environment Office. "We're just in the outskirts of the debris stream now. If you go out at night and stare at the sky, you'll probably only see a few Perseids per hour."

This will change, however, as August unfolds.

"Earth passes through the densest part of the debris stream sometime on August 12th. Then, you could see dozens of meteors per hour."

For sky watchers in North America, the watch begins after nightfall on August 11th and continues until sunrise on the 12th. Veteran observers suggest the following strategy: Unfold a blanket on a flat patch of ground. (Note: The middle of your street is not a good choice.) Lie down and look up. Perseids can appear in any part of the sky, their tails all pointing back to the shower's radiant in the constellation Perseus. Get away from city lights if you can.

There is one light you cannot escape on August 12th. The 55% gibbous Moon will glare down from the constellation Aries just next door to the shower's radiant in Perseus. The Moon is beautiful, but don't stare at it. Bright moonlight ruins night vision and it will wipe out any faint Perseids in that part of the sky.



Above: Looking northeast around midnight on August 11th-12th. The red dot is the Perseid radiant. Although Perseid meteors can appear in any part of the sky, all of their tails will point back to the radiant. Image copyright: Spaceweather.com, used with permission.

The Moon is least troublesome during the early evening hours of August 11th. Around 9 to 11 p.m. local time (your local time), both Perseus and the Moon will be hanging low in the north. This low profile reduces lunar glare while positioning the shower's radiant for a nice display of Earthgrazers.

"Earthgrazers are meteors that approach from the horizon and skim the atmosphere overhead like a stone skipping across the surface of a pond," explains Cooke. "They are long, slow and colorful—among the most beautiful of meteors." He notes that an hour of watching may net only a few of these at most, but seeing even one can make the whole night worthwhile.

The Perseids are coming. Enjoy the show.

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Possible Meteorite Imaged by Opportunity Rover
<sup>by Staff Writers
Pasadena CA (JPL) Aug 05, 2009


This image of "Block Island" was taken on July 28, 2009,
with the front hazard-identification camera on
NASA's Mars Exploration Rover Opportunity.</sup>

The Opportunity rover has eyed an odd-shaped, dark rock, about 0.6 meters (2 feet) across on the surface of Mars, which may be a meteorite.
The team spotted the rock called "Block Island," on July 18, 2009, in the opposite direction from which it was driving. The rover then backtracked some 250 meters (820 feet) to study it closer.

Scientists will be testing the rock with the alpha particle X-ray spectrometer to get composition measurements and to confirm if indeed it is a meteorite.

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Op vrijdag 7 augustus 2009 00:45 schreef ExperimentalFrentalMental het volgende:
De meteorenregen lijkt rechtstreeks uit de planeet Perseus te komen en heet daarom Perseïden.

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Planets collide in deep space

Two distant planets orbiting a young star apparently smashed into each other at high speeds thousands of years ago in cosmic pileup of cataclysmic proportions, astronomers announced Monday.

Telltale plumes of vaporized rock and lava leftover from the collision revealed its existence to NASA's Spitzer Space Telescope, which picked up signatures from the impact in recent observations.

The two-planet pileup occurred within the last few thousand years or so - a relatively recent cosmic timeframe. The smaller of the two bodies - a planet about the size of Earth's moon, according to computer models - was apparently destroyed by the crash. The other was most likely a Mercury-sized-planet and survived, albeit severely dented.

"This collision had to be huge and incredibly high-speed for rock to have been vaporized and melted," said Carey Lisse of the Johns Hopkins University Applied Physics Laboratory in Maryland, lead author of a paper describing the findings in the Aug. 20 issue of the Astrophysical Journal.

Researchers believe the planets were moving at about 22,400 mph (10 kilometers per second) before the crash. The violent wreck released amorphous silica rock, or melted glass, and hardened chunks of lava called tektites. Spitzer also spotted large clouds of orbiting silicon monoxide gas created when the rock was vaporized.

This is a really rare and short-lived event, critical in the formation of Earth-like planets and moons," Lisse said. "We're lucky to have witnessed one not long after it happened."

Infrared detectors on Spitzer found the traces of rocky rubble and re-frozen lava around a young star, called HD 172555, still in the early stages of planet formation. The system is about 100 light-years from Earth. One light-year is the distance light travels in a year six trillion miles (9.7 trillion km).

similar fender-bender is thought to have formed Earth's moon more than 4 billion years ago, when a body the size of Mars rammed into Earth.

"The collision that formed our moon would have been tremendous, enough to melt the surface of Earth," said co-author Geoff Bryden of NASA's Jet Propulsion Laboratory in California. "Debris from the collision most likely settled into a disk around Earth that eventually coalesced to make the moon. This is about the same scale of impact we're seeing with Spitzer - we don't know if a moon will form or not, but we know a large rocky body's surface was red hot, warped and melted."

In fact, such violent encounters seem to have been common in our own solar system's early history. For example, giant impacts are thought to have stripped Mercury of its outer crust, tipped Uranus on its side, and spun Venus backward.

As recently as last month, a small space rock slammed into Jupiter, making a large black bruise.

In general, rocky planets like Earth coalesce and grow when small rocks crash and clump together, merging their cores.

The system around HD 172555 is a relative baby at only 12 million years old, compared to our solar system's age of 4.5 billion years.

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Op woensdag 12 augustus 2009 00:08 schreef ExperimentalFrentalMental het volgende:
knip

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Op woensdag 12 augustus 2009 01:00 schreef star_gazer het volgende:
*meldt

Perseiden zijn al jarenlang zeer tegenvallend. Dit jaar hebben we ook nog eens volle maan, dus verwacht er niet veel van. Wacht liever op de Leoniden in november.

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Op woensdag 12 augustus 2009 00:32 schreef ExperimentalFrentalMental het volgende:
En niet vergeten de komende nacht allemaal naar buiten te gaan en naar de sterrenhemel te staren!
de Perseïden komen eraan

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Op donderdag 23 juli 2009 20:02 schreef Meursault het volgende:
Ik lees ook weer mee.

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Op maandag 17 augustus 2009 02:44 schreef ExperimentalFrentalMental het volgende:
16-08-2009

Spectaculaire meteoor te zien

-KNIP-

hier baal ik nou echt van!
Ik stond gisteravond de sterren te bewonderen met de sterrenkijker, maar pas vanaf 23:00 uur... Heb ik weer, na de overbewolking tijdens de¨Perseïden, iets spectaculairs gemist

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Scenario 1 is het huidige scenario dat NASA voor ogen heeft: de shuttle blijft vliegen tot 2011 en in 2015 wordt ISS afgedankt. ISS wordt tot 2015 bereikt met behulp van Russische Sojoez raketten, daarna de Orion, die met een Ares-I raket gelanceerd wordt. Later komt de Ares-V raket, die NASA astronauten naar de maan kan brengen. De eerste maanlanding staat dan gepland in 2024 waarna men werkt aan een maanbasis. Het nadeel van dit scenario is een lang gat in de mogelijkheden voor bemande ruimtevaart: van 2011 t/m 2018. Ook het al in 2015 afdanken van ISS ligt politiek gevoelig.

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Op zondag 16 augustus 2009 04:28 schreef ExperimentalFrentalMental het volgende:
15-08-2009

Superreus Betelgeuze blaast bellen uit

[ afbeelding ]

Betelgeuze, een van de grootste sterren die men kent, is bezig zichzelf op te koken. Dat hebben astronomen afgeleid uit de meest gedetailleerde waarnemingen die tot nu toe aan deze ster zijn verricht (binnenkort te verschijnen in Astronomy & Astrophysics). Van Betelgeuze is bekend dat hij grote hoeveelheden gas verliest, de gehele massa van de zon in tienduizend jaar, maar hoe dat precies gebeurt was niet duidelijk. De nieuwe waarnemingen laten zien dat het gas niet overal gelijkmatig uit het oppervlak wegstroomt, maar in de vorm van reusachtige bellen die door dieperliggende convectiebewegingen uit de ster worden weggeduwd.

Betelgeuze is een heldere ster in het sterrenbeeld Orion, op ongeveer 600 lichtjaar van de aarde. Het is een superreus, een heel zware ster die het einde van een kort leven nadert. Hij ontstond enkele miljoenen jaren geleden – toen op aarde de eerste mensachtigen verschenen – en heeft nog enkele (tien)duizenden jaren te gaan. Dan is zijn energie op en explodeert hij. De ster is nu zo groot dat hij op de plaats van de zon gezet tot bijna de baan van Jupiter zou reiken. Vanaf de aarde gezien is het echter toch maar een piepklein schijfje en om dat te bestuderen zijn speciale technieken nodig.

Eén groep astronomen werkte met een 8 meter-telescoop van de Europese Zuidelijke Sterrenwacht in Chili. Die is voorzien van een systeem dat de beeldverstorende werking van de aardatmosfeer opheft. Een tweede groep astronomen combineerde het licht van drie kleinere telescopen, om zo één reuzentelescoop van 48 meter diameter te simuleren. Hierdoor konden details ter grootte van circa 0,01 boogseconde worden onderscheiden: een knikker gezien op een afstand van duizend kilometer.

Zo konden de astronomen waarnemen dat het oppervlak van Betelgeuze plaatselijk met snelheden tot 15 meter per seconde op en neer beweegt. Deze convectiebewegingen – vergelijkbaar met die in een pan kokend water – leiden er toe dat reusachtige gasbellen de ster verlaten, om zich in de ruimte te verspreiden en op te lossen. Rond de ster werden drie uitgestrekte gaspluimen waargenomen die de overblijfselen daarvan zouden zijn. De grootste strekt zich uit tot minstens zes maal de diameter van de ster, ofwel de afstand zon-Neptunus. Het sterfbed van Betelgeuze heeft dus de omvang van ons zonnestelsel.

(nrc)

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Op vrijdag 21 augustus 2009 01:44 schreef Parafernalia het volgende:

[..]

Dat ding is echt zo belachelijk groot

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Glycine In The Grid
<sup>by Staff Writers
Greenbelt MD (SPX) Aug 20, 2009


Comet particle tracks in aerogel.
Credit: Stardust, JPL, NASA</sup>

NASA scientists have discovered glycine, a fundamental building block of life, in samples of comet Wild 2 returned by NASA's Stardust spacecraft.
"Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Greenbelt, Md.

"Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Elsila is the lead author of a paper on this research accepted for publication in the journal Meteoritics and Planetary Science. The research was presented during the meeting of the American Chemical Society at the Marriott Metro Center in Washington, August 16.

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare," said Dr. Carl Pilcher, Director of the NASA Astrobiology Institute which co-funded the research.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins.

Stardust passed through dense gas and dust surrounding the icy nucleus of Wild 2 (pronounced "Vilt-2") on January 2, 2004. As the spacecraft flew through this material, a special collection grid filled with aerogel - a novel sponge-like material that's more than 99 percent empty space - gently captured samples of the comet's gas and dust.

The grid was stowed in a capsule which detached from the spacecraft and parachuted to Earth on January 15, 2006. Since then, scientists around the world have been busy analyzing the samples to learn the secrets of comet formation and our solar system's history.

"We actually analyzed aluminum foil from the sides of tiny chambers that hold the aerogel in the collection grid," said Elsila. "As gas molecules passed through the aerogel, some stuck to the foil. We spent two years testing and developing our equipment to make it accurate and sensitive enough to analyze such incredibly tiny samples."

Earlier, preliminary analysis in the Goddard labs detected glycine in both the foil and a sample of the aerogel. However, since glycine is used by terrestrial life, at first the team was unable to rule out contamination from sources on Earth.

"It was possible that the glycine we found originated from handling or manufacture of the Stardust spacecraft itself," said Elsila. The new research used isotopic analysis of the foil to rule out that possibility.

Isotopes are versions of an element with different weights or masses; for example, the most common carbon atom, Carbon 12, has six protons and six neutrons in its center (nucleus). However, the Carbon 13 isotope is heavier because it has an extra neutron in its nucleus.

A glycine molecule from space will tend to have more of the heavier Carbon 13 atoms in it than glycine that's from Earth. That is what the team found. "We discovered that the Stardust-returned glycine has an extraterrestrial carbon isotope signature, indicating that it originated on the comet," said Elsila.

The team includes Dr. Daniel Glavin and Dr. Jason Dworkin of NASA Goddard. "Based on the foil and aerogel results it is highly probable that the entire comet-exposed side of the Stardust sample collection grid is coated with glycine that formed in space," adds Glavin.

"The discovery of amino acids in the returned comet sample is very exciting and profound," said Stardust Principal Investigator Professor Donald E. Brownlee of the University of Washington, Seattle, Wash. "It is also a remarkable triumph that highlights the advancing capabilities of laboratory studies of primitive extraterrestrial materials."

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Op vrijdag 21 augustus 2009 02:16 schreef intraxz het volgende:

[..]

Plaatje van Betelgeuse
[ afbeelding ]

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NASA Selects Target Crater for Lunar Impact

Sept. 11, 2009: NASA's Lunar Crater Observation and Sensing Satellite (LCROSS) is racing toward a double-impact on the moon at 7:30 am EDT on Oct. 9th. Today NASA announced exactly where the crash will take place.

The target crater is Cabeus A. It was selected after an extensive review of the best places to excavate frozen water at the lunar south pole


^{Above: Craters of interest around the lunar south pole. LCROSS is targeting Cabeus A. Image credit: NMSU/MSFC Tortugas Observatory}

"The selection of Cabeus A was a result of a vigorous debate within the lunar science community. We reviewed the latest data from Earth-based observatories and our fellow lunar missions Kaguya, Chandrayaan-1, and the Lunar Reconnaissance Orbiter," says Anthony Colaprete, LCROSS project scientist and principle investigator at NASA's Ames Research Center. "The team is looking forward to wealth of information this unique mission will produce."

LCROSS will search for ice by plunging its spent upper-stage Centaur rocket into the permanent shadows of Cabeus A, where water might be trapped in frozen form. The LCROSS satellite will then fly into the plume of debris kicked up by the impact and measure the properties of the plume before it also collides with the lunar surface.


Sign up for EXPRESS SCIENCE NEWS delivery

The LCROSS team selected Cabeus A based on a set of conditions that includes favorable illumination of the debris plume for visibility from Earth, where astronomers will be watching closely. Cabeus A also has a high concentration of hydrogen (a constituent of water, H2O) and favorable terrain such as a flat floor, gentle slopes and the absence of large boulders.

Professional astronomers will use many of Earth's most capable observatories to monitor the impacts. These observatories include the Infrared Telescope Facility and Keck telescope in Hawaii; the Magdalena Ridge and Apache Ridge Observatories in New Mexico and the MMT Observatory in Arizona; the newly refurbished Hubble Space Telescope; and the Lunar Reconnaissance Orbiter, among others.

Amateur astronomers can monitor the impact, too. Observing tips may be found here.

"Telescopes participating in the LCROSS Observation Campaign will provide observations from different vantage points using different types of measurement techniques," says Jennifer Heldmann, lead for the LCROSS Observation Campaign at Ames. "These multiple observations will complement the LCROSS spacecraft data to help determine whether or not water ice exists in Cabeus A."

During a media briefing Sept. 11, Daniel Andrews, LCROSS project manager at Ames, provided a mission status update: The spacecraft is healthy and has enough fuel to successfully accomplish all mission objectives. Andrews also announced the dedication of the LCROSS mission to the memory of legendary news anchor, Walter Cronkite, who provided coverage of NASA's missions from the beginning of America's manned space program to the age of the space shuttle.


^{Above: The LCROSS mission has been dedicated to the memory of Walter Cronkite, who covered NASA missions from Mercury through the space shuttle. Image credit: CBS News. [/b]}

"Dad would sure be proud to be part, if just in name, of getting humans back up to the moon and beyond," says Chip Cronkite, son of the famed news anchor.

"We're looking forward to October 9th," Andrews says. "The next 28 days will undoubtedly be very exciting."

Cabeus A, here we come!

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Op dinsdag 15 september 2009 09:02 schreef Bensel het volgende:
Elke witte pixel is zo'n beetje een ster

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Op dinsdag 15 september 2009 00:16 schreef intraxz het volgende:
http://www.eso.org/gallery/d/136986-2/phot-32a-09-fullres.jpg
High res versie.

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Op dinsdag 15 september 2009 12:20 schreef intraxz het volgende:

[..]

Het plaatje is 2000 x 4000. Dat zijn 8 miljoen pixels. En dat komt nog lang niet in de buurt van het geschatte aantal sterren in de melkweg. Kun je nagaan..

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Herschel scans hidden Milky Way

A remarkable view of our galaxy has been obtained by Europe's billion-euro Herschel Space Observatory.

The telescope was put in a special scanning mode to map a patch of sky.

The images reveal in exquisite detail the dense, contorted clouds of cold gas that are collapsing in on themselves to form new stars.

Herschel, which has the largest mirror ever put on an orbiting telescope, was launched in May as a flagship mission of the European Space Agency.

It is tuned to see far-infrared wavelengths of light and is expected to give astronomers significant insights into some of the fundamental processes that shape the cosmos.

Herschel's great advantage is that its sensitivity allows it to see things that are beyond the vision of other space telescopes, such as Hubble.

A prime goal is to understand the mechanisms that control the earliest phases of stellar evolution.

Rich data return

Herschel's special scanning mode means it has to shift its gaze back and forth across an area of sky, which in this case was about 16 times as big as the size of the Moon as viewed from Earth.

The observatory is tuned to see the Universe in the far-infrared
Its 3.5m diameter mirror is the largest ever flown in space
Herschel can probe clouds of gas and dust to see stars being born
It will investigate how galaxies have evolved through time
The mission will end when its helium refrigerant boils off

The telescope was looking towards the plane of our Milky Way Galaxy, in the direction of the Southern Cross constellation.

The scanning mode works with two of Herschel's three instruments operating in tandem.

The UK-led Spire camera responds to longer wavelengths of light (250-500 microns - that is about 500-1,000 times longer than the wavelengths of light we detect with our eyes).

The German-led Pacs camera covers shorter wavelengths (70-170 microns).

Their pictures reveal a chaotic scene of gas and dust, and stars in all stages of development.

The material being observed is very cold - typically less than minus 170C (100 kelvin).

Anomaly investigation

Scientists say the images are information-rich.

"Our wavelength coverage is telling us details about the physics," explained Professor Matt Griffin, of Cardiff University, who is the Spire principal investigator.

"Spire is particularly good at seeing the cold and extended material which might correspond, for instance, to the earliest stages of star formation.

"Pacs is slightly more sensitive to what we would call warmer material, although by any normal standards it is still extremely cold; and that material might be closer to regions where stars have already formed and have been heated up by the young stellar objects."

Herschel intends to study large regions of the Milky Way in its combined Spire-Pacs scanning mode. The instruments will, of course, also work independently.

The mission is due to go into routine operations in the next few weeks. However, its third instrument is currently down after experiencing a fault.

Engineers can switch to a back-up system to reactivate the Heterodyne Instrument for the Far Infrared (HiFi), but they do not intend to do that until they have satisfied themselves the cause the anomaly is properly understood.

The Dutch-led HiFi is a spectrometer that will identify elements and molecules in the clouds of gas and dust which give rise to stars.

Bron: BBC.

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New ring detected around Saturn
<sup>By Jonathan Amos
Science reporter, BBC News



Saturn (Nasa)
The outer E-ring on Saturn extends about 240,000km into space</sup>

A colossal new ring has been identified around Saturn.

The dusty hoop extends some 13 million km (eight million miles) from the planet, about 50 times further out into space than its more familiar rings.

Scientists tell the journal Nature that the tenuous ring is probably made up of debris kicked off Saturn's moon Phoebe by small impacts.

They think this dust then migrates towards the planet where it is picked up by another Saturnian moon, Iapetus.

The discovery would appear to resolve a longstanding mystery in planetary science: why the walnut-shaped Iapetus has a two-tone complexion, with one side of the moon significantly darker than the other.

"It has essentially a head-on collision. The particles smack Iapetus like bugs on a windshield," said Anne Verbiscer from the University of Virginia, US.

Observations of the material coating the dark face of Iapetus indicate it has a similar composition to the surface material on Phoebe.

The scale of the new ring feature is astonishing. Nothing like it has been seen elsewhere in the Solar System.

The more easily visible outlier in Saturn's famous bands of ice and dust is its E-ring, which encompasses the orbit of the moon Enceladus. This circles the planet at a distance of just 240,000km.

The newly identified torus is not only much broader and further out, it is also tilted at an angle of 27 degrees to the plane on which the more traditional rings sit.

This in itself strongly links the ring's origin to Phoebe, which also takes a highly inclined path around Saturn.

Scientists suspected the ring might be present and had the perfect tool in the Spitzer space telescope to confirm it.

The US space agency observatory is well suited to picking up the infrared signal expected from cold grains of dust about 10 microns (millionths of a metre) in size.

The ring would probably have a range of particle sizes - some bigger than this, and some smaller - and modelling indicates the pressure of sunlight would push the smallest of these grains towards the orbit of Iapetus, which is circling Saturn at a distance of 3.5 million km.

"The particles are very, very tiny, so the ring is very, very tenuous; and actually if you were standing in the ring itself, you wouldn't even know it," Dr Verbiscer told BBC News.

"In a cubic km of space, there are all of 10-20 particles."

Indeed, so feeble is the ring that scientists have calculated that if all the material were gathered up it would fill a crater on Phoebe no more than a kilometre across.

The moon is heavily pockmarked. It is clear that throughout its history, Phoebe has been hit many, many times by objects.

Some will also have been orbiting Saturn; others will have come from deep space.

Bron: BBC.

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Updated SMART-1 Image Of New Target For LCROSS Impact
<sup>by Staff Writers
Paris, France (ESA) Oct 08, 2009




New LCROSS impact target Cabeus: Mosaic of 4 images taken by the Advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 mission. The SMART-1 images forming the mosaic have been taken at different epochs with different illumination conditions: in January 2005 from a distance of 1037 km and on February 2006 from a distance of 622 km. The SMART-1 AMIE mosaic size is 100 km. The dots at the center of the image indicate the impact points for the LCROSS Centaur stage and shepherd spacecraft well placed within the shadowed area. Image credit: B.Grieger, B.H. Foing and ESA/SMART-1/ AMIE team</sup>


The European Space Agency's SMART-1 team has released an updated image of the future impact site of NASA's Lunar Crater Observation and Sensing Satellite (LCROSS), after the LCROSS team announced a new target last week. LCROSS will search for water ice on the Moon by making two impacts into a crater named Cabeus at the lunar South Pole. The impacts are scheduled for 11:31:19 UTC and 11:35:45 UTC on 9 October 2009.
Bjoern Grieger, the liaison scientist for SMART-1's AMIE camera, and Bernard Foing, ESA SMART-1 Project Scientist, have searched through SMART-1's database for images of Cabeus, taken four years ago. The SMART-1 images are at high resolution as the spacecraft was near its closest distance of 500 km from the South Pole.

The SMART-1 images of LCROSS potential targets were discussed on 18 September at lunar sessions of European Planetary Science Congress (EPSC) in Potsdam, Germany.

The Cabeus crater interior is permanently shadowed, so ice lying inside the crater could be protected from the Sun's harsh rays. LCROSS will send the upper stage Centaur rocket crashing into Cabeus and a shepherd spacecraft will fly into the plume of dust generated and measure its properties before making a second impact with the lunar surface. Astronomers will observe both impacts using ground and space-based telescopes.

The SMART-1 spacecraft also concluded its mission with a controlled bouncing impact on 3 September 2006. The event was observed with ground-based telescopes (a "dry run" for LCROSS), and the flash from the impact was detected at infrared wavelengths.

"The Cabeus topographic features as observed by SMART-1 vary greatly during the lunar rotation and the yearly seasons due to the polar grazing illumination conditions", said Foing.

"The floor of Cabeus near LCROSS targets shows a number of small craters and seems old enough to have accumulated water ice delivered from comets and water-rich asteroids, and might have kept it frozen in its shadowed area."

"These ESA SMART-1 observations of the Cabeus crater can help in the final planning and interpretation of LCROSS impact observations", he added.

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ESA schort Mars-missie op
^{Van onze verslaggever Peter van Ammelrooy
Gepubliceerd op 13 oktober 2009 12:37, bijgewerkt op 13 oktober 2009 14:41}

AMSTERDAM - De Europese ruimtevaartorganisatie ESA past zijn ambities aan het budget aan en gaat later naar Mars – met hulp van de Amerikanen.

Tijdens een vergadering in Parijs is besloten om ExoMars, een expeditie naar de rode planeet, met twee jaar uit te stellen, tot 2018, meldt de BBC. De missie zal worden uitgevoerd in samenwerking met de Verenigde Staten. De wijzigingen waren eerder dit jaar al voorgesteld door de ESA omdat de ministers van de lidstaten in november onvoldoende geld beschikbaar stelden voor het project.

Met ExoMars wil de ESA een kunstmaan in een baan om Mars brengen en een robotkarretje op het oppervlak van de planeet laten landen. Deze rover is voorzien van een boor die tot twee meter diep in de bodem kan boren. Net als de NASA-robotjes Spirit en Opportunity moet de missie uitwijzen of er leven op Mars is of is geweest.

In november vorig jaar besloten de ministers van de lidstaten van de ESA 850 miljoen euro opzij te zetten voor ExoMars. Dat is te weinig om de missie te bekostigen.

Geldgebrek
Ook de aangepaste plannen moeten nog door de politieke molen. ExoMars zit al een jaar of vijf in de pijplijn. Oorspronkelijk zouden sonde, landingsvaartuig en robot in 2011 worden gelanceerd. Maar omdat de grootste financier van het project, Italië, zijn toezeggingen niet nakwam is de missie al drie keer uitgesteld.

De nieuwe plannen voorzien wel in een kleinschalige, voorbereidende missie met een kunstmaan die om Mars draait en een kleine, vaste sonde die op de planeet landt. Die verkenner zou in 2016 worden gelanceerd.

De Verenigde Staten willen in 2013 een nieuwe robot, Curiosity (die tot mei dit jaar als de Mars Science Laboratory MSL bekend stond), naar Mars sturen. Ook dat is al weer twee jaar later dan gepland. Die missie wordt daarmee waarschijnlijk 400 miljoen dollar duurder – een stijging die bovenop de geraamde kosten van 2 miljard dollar komt.

Bron: De Volkskrant.

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European commands space station

Belgian astronaut Frank De Winne has spoken of his pride at taking command of the International Space Station.

The European Space Agency astronaut is the first national outside of the US and Russia to lead a crew on the orbiting platform.

De Winne took the role at the weekend when the previous commander, Gennady Padalka, left to return to Earth.

The Belgian told reporters on Tuesday that his appointment was a great moment for the European Astronaut Corps.

"I have always been proud to be European and the Europeans of course have a big heritage as explorers; and so, therefore, for me, it is a big honour to be the first European to be a commander of the space station," he said.

De Winne made his remarks during a live link-up with the ISS. He took questions while floating inside the Columbus module, Europe's science lab attached to the platform.

The Esa astronaut launched to the station in May. He will stay aboard the platform until December when he is due to fly back to Earth in a Soyuz capsule.

Bron: BBC, lees meer…

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[UPD] Meteoor boven Nederland ontploft

Volgens Twitter is ons land zojuist aan een ramp ontsnapt. Vele Twitteraars werden rond zeven uur vanavond opgeschrikt door een meteoor. Deze is onder andere gesignaleerd boven Zwolle, Ede, Breda, Huizen en Arnhem.

Volgens sommige gebruikers zijn we nog niet van de problemen af. De vuurbal zou zijn neergestort in de Noordzee. [Knip]

UPDATE

Veel Nederlanders hebben vanavond rond zeven uur een vuurbol in de lucht gezien. De Groningse sterrenkundige Theo Jurriens bevestigde dat het om een zeer heldere meteoor ging die op een gegeven moment in drie stukken uiteenspatte.

Jurriens zei uit heel Nederland ongeveer honderd meldingen te hebben ontvangen van mensen die de vuurbol hebben gezien. Het KNMI meldde ook een behoorlijk aantal telefoontjes te hebben ontvangen.


Foto Credit Jan de Vries

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Een heuse tsunami zou ons land nu bedreigen. We houden ons hart vast, het is dan ook al bijna 2012.

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Op dinsdag 13 oktober 2009 22:48 schreef Edwinuss het volgende:

[..]

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Op dinsdag 13 oktober 2009 23:01 schreef -CRASH- het volgende:

[..]

Echt onzin talk... Zal het ff weghalen

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Op dinsdag 13 oktober 2009 23:24 schreef ExperimentalFrentalMental het volgende:
Cool!
Heeft iemand de meteoor gezien?

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Will NASA Sail the Great Lakes of Titan?

_{Bron: Wikimedia Commons. Maker: NASA/JPL/GSFC. Publiek Domein.
Vergelijking tussen een meer op Titan en Lake superior}
The world's astrobiology community is all abuzz over one of NASA's most exciting Discovery Mission proposals ever considered to explore the vast methane lakes in the Northern Polar region of Saturn's moon, Titan. This Titan ocean "Lake Lander" will be an Apollo-mission-like bell-shaped capsule that would be dropped directly into one of the Titan target lakes with a mast to hold a camera. The lake-born probe would use a nuclear-powered engine to run experiments and return data to Earth. When interviewed recently on National Public Radio (listen to the audio below).

Saturn's orange moon Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to data from NASA's Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes. Titan is a big laboratory where several of the world's leading space scientists get to play with atmospheres on a planetary scale.

At an eye popping minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan has a surface of liquid hydrocarbons in the form of methane and ethane with tholins believed to make up its dunes. The term "tholins," coined by Carl Sagan in 1979, describe the complex organic molecules at the heart of prebiotic chemistry.

Before the first Cassini Mission flyby's Robert Brown who led Cassini's visual and infrared mapping spectrometer (VIMS) team, said: "We know VIMS will see through the haze to Titan's surface. At closest approach - 1,200 kilometers (745 miles) - we'll have 600-meter-pixel resolution. We'll be able to see very small geologic features. We'll get very high resolution looks at atmospheric phenomena, too. But from my perspective, the really important thing about this encounter is really digging down below the atmosphere and getting our first real glimpse of Titan geology.

Bron: Daily Galaxy, lees meer…

Interview op NPR.org

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Peering far beyond our solar system, NASA researchers have detected the basic chemistry for life in a second hot gas planet, advancing astronomers toward the goal of being able to characterize planets where life could exist. The planet is not habitable but it has the same chemistry that, if found around a rocky planet in the future, could indicate the presence of life.

"It's the second planet outside our solar system in which water, methane and carbon dioxide have been found, which are potentially important for biological processes in habitable planets," said researcher Mark Swain of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "Detecting organic compounds in two exoplanets now raises the possibility that it will become commonplace to find planets with molecules that may be tied to life."

Swain and his co-investigators used data from two of NASA's orbiting Great Observatories, the Hubble Space Telescope and Spitzer Space Telescope, to study HD 209458b, a hot, gaseous giant planet bigger than Jupiter that orbits a sun-like star about 150 light years away in the constellation Pegasus. The new finding follows their breakthrough discovery in December 2008 of carbon dioxide around another hot, Jupiter-size planet, HD 189733b. Earlier Hubble and Spitzer observations of that planet had also revealed water vapor and methane.

The detections were made through spectroscopy, which splits light into its components to reveal the distinctive spectral signatures of different chemicals. Data from Hubble's near-infrared camera and multi-object spectrometer revealed the presence of the molecules, and data from Spitzer's photometer and infrared spectrometer measured their amounts.

"This demonstrates that we can detect the molecules that matter for life processes," said Swain. Astronomers can now begin comparing the two planetary atmospheres for differences and similarities. For example, the relative amounts of water and carbon dioxide in the two planets is similar, but HD 209458b shows a greater abundance of methane than HD 189733b. "The high methane abundance is telling us something," said Swain. "It could mean there was something special about the formation of this planet."

Other large, hot Jupiter-type planets can be characterized and compared using existing instruments, Swain said. This work will lay the groundwork for the type of analysis astronomers eventually will need to perform in shortlisting any promising rocky Earth-like planets where the signatures of organic chemicals might indicate the presence of life.

Rocky worlds are expected to be found by NASA's Kepler mission, which launched earlier this year, but astronomers believe we are a decade or so away from being able to detect any chemical signs of life on such a body.

If and when such Earth-like planets are found in the future, "the detection of organic compounds will not necessarily mean there's life on a planet, because there are other ways to generate such molecules," Swain said. "If we detect organic chemicals on a rocky, Earth-like planet, we will want to understand enough about the planet to rule out non-life processes that could have led to those chemicals being there."

"These objects are too far away to send probes to, so the only way we're ever going to learn anything about them is to point telescopes at them. Spectroscopy provides a powerful tool to determine their chemistry and dynamics."

You can follow the history of planet hunting from science fiction to science fact with NASA's PlanetQuest Historic Timeline at http://planetquest.jpl.nasa.gov/timeline/ .

This interactive web feature, developed by JPL, conveys the story of exoplanet exploration through a rich tapestry of words and images spanning thousands of years, beginning with the musings of ancient philosophers and continuing through the current era of space-based observations by NASA's Spitzer and Kepler missions. The timeline highlights milestones in culture, technology and science, and includes a planet counter that tracks the pace of exoplanet discoveries over time.

More information about exoplanets and NASA's planet-finding program is at http://planetquest.jpl.nasa.gov .

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency and is managed by NASA's Goddard Space Flight Center in Greenbelt, Md. The Space Telescope Science Institute, Baltimore, Md., conducts Hubble science operations. The institute is operated for NASA by the Association of Universities for research in Astronomy, Inc., Washington, D.C.

JPL manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Caltech manages JPL for NASA

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Op zaterdag 24 oktober 2009 01:13 schreef ExperimentalFrentalMental het volgende:
23-10-2009

NASA wil maanatmosfeer onderzoeken

[ afbeelding ]

Het Amerikaanse ruimteagentschap NASA wil, voor het te laat is, onderzoek doen aan de bijzonder ijle atmosfeer van de maan.

Naar verwachting zal de menselijke activiteit op het maanoppervlak de komende decennia namelijk flink toenemen. En waar mensen zijn, dwarrelt stof op, worden raketten gelanceerd en treden allerlei vormen van vervuiling op.

De onderzoekers willen dat vóór zijn, omdat anders nooit meer kan worden vastgesteld wat de natuurlijke samenstelling van de maanatmosfeer is. Vandaar hun plannen voor de Lunar Atmosphere and Dust Environment Explorer (LADEE), die in 2012 gelanceerd zou moeten worden.

De maan heeft zijn atmosfeer overigens voor een belangrijk deel te danken aan de zon: zijn oppervlak staat bloot aan een bombardement van ultraviolet zonlicht en geladen deeltjes van de zonnewind, waardoor atomen en moleculen vrijkomen. Ook inslagen van micrometeorieten en gassen uit het inwendige van de maan dragen een steentje bij.

De instrumenten van LADEE zullen de concentraties van 18 verschillende stoffen in de maanatmosfeer meten.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

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Astronomen hebben licht waargenomen dat 13,1 miljard jaar onderweg geweest is naar de aarde. Van verder weg hebben telescopen nog nooit iets waargenomen, schrijven de astronomen in Nature.
Het licht kwam van een ster die op een afstand van 13,1 miljard lichtjaar explodeerde. Een internationaal team van astronomen zag het licht gedurende tien dagen door telescopen op Hawaï.

Volgens experts is het een belangrijke ontdekking, die een doorbraak kan zijn in het onderzoek naar de 'kosmische middeleeuwen'. Daaronder wordt de tijd verstaan tussen de Big Bang en het ontstaan van de eerste sterrenstelsels.

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Japanese freighter makes re-entry

Japan's new space freighter has burned up in the Earth's atmosphere after completing its mission to the International Space Station (ISS).

The H-II Transfer Vehicle (HTV) carried 4.5 tonnes of supplies to the orbiting platform, including scientific equipment for its Kibo laboratory.

The HTV, which had arrived at the ISS in September, was released on Friday.

A series of engine firings then took the vehicle into a controlled but destructive dive over the Pacific.

A statement from the Japanese space agency said the freighter re-entered the atmosphere at 0626 Japan Standard Time (2126 GMT Sunday).

Most of the vehicle components would have been destroyed although some debris was expected to survive and fall into the ocean, it added.

The HTV is one of Japan's major contributions to the orbiting space station project and is part of the barter agreement it has with the other station partners to pay its way.

The HTVs that follow in the coming years will play a critical role in servicing the ISS after the US space shuttles are retired.

It is the first spacecraft to visit the ISS which does not drive itself all the way to berthing. Rather, it simply parks up under the bow of the station to allow the platform's Canadarm2 to manage the final stage of attachment.

When the US shuttles retire at the end of next year or the beginning of 2011, the ISS project will become dependent on five robotic freighters for its logistics:

• The Russian Progress and European ATV have already demonstrated their flight capability. Four more ATVs have been booked to fly to the station, one a year starting in 2010.

• Following on from the first HTV mission, Japan plans a further six flights through to 2015.

• Two commercial US suppliers, SpaceX and Orbital Sciences, are in the process of developing their Dragon and Cygnus supply ships. The first of these is scheduled to deliver supplies to the ISS no earlier than the end of 2010.

HTV and Dragon are particularly important because of their ability to deliver larger items in their unpressurised compartments that would not normally fit through the docking port of a pressurised compartment.

Bron: BBC

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Op dinsdag 3 november 2009 10:49 schreef Iblis het volgende:
Physicist Makes New High-Res Panorama of Milky Way

[ afbeelding ]

Piecing together 3000 individual photographs, a physicist has made a new high-resolution panoramic image of the full night sky, with the Milky Way galaxy as its centerpiece. Axel Mellinger, a professor at Central Michigan University, describes the process of making the panorama in the forthcoming issue of Publications of the Astronomical Society of the Pacific. An interactive version of the picture can viewed on Mellinger’s website: http://home.arcor.de/axel.mellinger/.

“This panorama image shows stars 1000 times fainter than the human eye can see, as well as hundreds of galaxies, star clusters and nebulae,” Mellinger said. Its high resolution makes the panorama useful for both educational and scientific purposes, he says.

Mellinger spent 22 months and traveled over 26,000 miles to take digital photographs at dark sky locations in South Africa, Texas and Michigan. After the photographs were taken, “the real work started,” Mellinger said.

Simply cutting and pasting the images together into one big picture would not work. Each photograph is a two-dimensional projection of the celestial sphere. As such, each one contains distortions, in much the same way that flat maps of the round Earth are distorted. In order for the images to fit together seamlessly, those distortions had to be accounted for. To do that, Mellinger used a mathematical model—and hundreds of hours in front of a computer.

Another problem Mellinger had to deal with was the differing background light in each photograph.

“Due to artificial light pollution, natural air glow, as well as sunlight scattered by dust in our solar system, it is virtually impossible to take a wide-field astronomical photograph that has a perfectly uniform background,” Mellinger said.

To fix this, Mellinger used data from the Pioneer 10 and 11 space probes. The data allowed him to distinguish star light from unwanted background light. He could then edit out the varying background light in each photograph. That way they would fit together without looking patchy.

The result is an image of our home galaxy that no star-gazer could ever see from a single spot on earth. Mellinger plans to make the giant 648 megapixel image available to planetariums around the world.

Bron: Chicago Journals.

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Op vrijdag 6 november 2009 03:32 schreef ExperimentalFrentalMental het volgende:Die 'dampkring' zou dan een dikte van slechts tien centimeter hebben, een druk die tien keer zo hoog is als de druk in de kern van de aarde, en een dichtheid gelijk aan die van diamant. Het zwaartekrachtsveld aan het oppervlak van een neutronenster is honderd miljard keer zo groot als het zwaartekrachtsveld van de aarde.

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Op vrijdag 6 november 2009 10:43 schreef Handschoen het volgende:

[..]

Zou zo'n koolstof atmosfeer dan niet gewoon diamant zijn onder die drukken en zwaartekracht?? Een ster gecovered met een laag diamant .

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Op zondag 8 november 2009 00:54 schreef Apogist het volgende:

[..]

"diamond star thrills astronomers"
http://news.bbc.co.uk/2/hi/science/nature/3492919.stm

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Russia to resume ISS construction
^{By Anatoly Zak, Science reporter}

After a hiatus of almost a decade, Russia is set to resume construction of its share in the International Space Station (ISS) with the launch of a new module this week.

A Poisk ("Quest") Mini-Research Module-2 (MIM-2 in the Russian abbreviation) is set for launch from Baikonur Cosmodrome in Kazakhstan on Tuesday at 1422 GMT.

The spacecraft is essentially a twin of another Russian module - the Pirs Docking Compartment - added to the outpost in September 2001.

In the intervening years, economic problems kept further Russian pieces of the station on the ground and forced a significant scaling down of the Russian segment in comparison to its originally conceived architecture.

The MIM-2 module is only the first of three long-term components which Russia plans to add to the station over the next three years.

Another module, Mini-Research Module-1 or MIM-1, is currently undergoing final check-ups at RKK Energia, Russia's prime contractor for manned spacecraft. Energia is based in Korolev, near Moscow.

Multi-purpose module

Next month, MIM-1 is due to be shipped to Cape Canaveral, Florida. From here, it is to be launched to the station in the cargo bay of Nasa's space shuttle in May.

The MIM-1 spacecraft was recycled from the habitation section of the aborted science and power-supply platform (NEP). This platform was never completed due to lack of cash.

Despite their identification as research modules, the primary function of both craft is to provide four docking ports for the Russian segment of the station, which are needed to receive Soyuz and Progress transport ships.

After this year's increase of the outpost's crew from three to six people, the number of Soyuz spacecraft heading to the station is set to double from two to four annually.

At least two three-seat Soyuz spacecraft have to be docked to the station at all times to serve as a lifeboat for all crew members.

With the anticipated retirement of the shuttle within a year, and until the introduction of the Nasa's Orion spacecraft in the middle of the decade at the earliest, Russian Soyuz spacecraft would be the only way to transport people in and out of the station.

In addition to their function as "hallways" for the outpost, MIM-2 and MIM-1 sport interfaces for the installation of scientific instruments.

At the beginning of 2012, Russia plans to launch yet another long-delayed multi-purpose module, MLM, aboard a heavy-lift Proton rocket.

As one of its key elements, MLM would carry a European-built remote manipulator arm, known as ERA.

An 11m-long robot is expected to be deployed to shift up to eight tonnes of hardware, as well as astronauts, during assembly operations outside the Russian segment.

In order to add the MLM to the ISS, the Pirs docking compartment would have to be detached from its current position on the station and directed to a destructive re-entry into the Earth atmosphere.

Beyond 2020

Since Pirs currently serves as a "door" for all Russian spacewalks, all future work on the exterior of the Russian segment would be staged from the MIM-2 Poisk module.

With the improvement of the Russian economic situation, the nation's federal space agency, Roscosmos, started planning the development of two new modules, that would take on the responsibilities of the cancelled NEP science and power-supply platform.

Both spacecraft would feature specialised research labs and their own solar power systems. Provided sufficient funding were available, they would be launched to the station by Proton rockets in 2014 and 2015.

However, with the financial situation around the ISS looking clouded, Russia reserved the possibility of converting these new modules into the core of a new station, which could serve as a base for deep-space exploration in the following decades.

In June 2009, Simonetta Di Pippo, the European Space Agency's (Esa) director of human space flight, said she shared Russia's vision of the future space station as a platform for deep space missions.

"I have continuous consultations with officials in Russia. We meet every month to month-and-a-half, and now we are going to start joint work on the study for how to proceed beyond 2025," Ms Di Pippo said.

"We have a common idea that we would like to preserve a presence in [low-Earth orbit]. We are studying different scenarios, whether we need permanent presence or, maybe, a human-tended capability, and we can end up with a totally different solution in the end. But I don't believe we can leave Earth orbit."

Ms Di Pippo also said that although current Nasa plans for a return to the Moon left no major role for the station, that could change in the future.

"Even on the Nasa side, they have too many different developments (associated with Earth orbit) - including commercial involvement - which they cannot immediately give up," Ms Di Pippo said.

By the end of 2010, all partners in the ISS project expect to agree on an extension of the station's lifespan from 2015 to 2020 or even 2025.

Once a date for ending the life of the ISS had been decided, active planning for post-ISS manned spaceflight could begin in Russia, Europe and possibly the US.

Bron: BBC

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Op woensdag 11 november 2009 00:30 schreef ExperimentalFrentalMental het volgende:
10-11-2009

Onbekende planetoïde scheerde langs de aarde

[ afbeelding ]

Afgelopen vrijdag, 6 november, is onverwachts een kleine planetoïde langs de aarde gescheerd. Het naar schatting slechts zeven meter grote brok ruimtesteen, dat de aanduiding 2009 VA heeft gekregen, miste het aardoppervlak op ongeveer 14.000 kilometer. Daarmee was het, voor zover bekend, de op twee na dichtste nadering van een planetoïde die niet op aarde is neergestort.

Alleen in 2004 en 2008 vonden niptere missers plaats. Gemiddeld komen er ongeveer twee van zulke kleine planetoïden dicht langs de aarde, en eens in de vijf jaar ploffen de restanten van zo'n object op het aardoppervlak.

Het zonnestelsel wemelt van de planetoïden van deze grootte, maar doorgaans worden deze pas opgemerkt als ze de aarde al dicht genaderd zijn. Planetoïde 2009 VA is pas vijftien uur voor zijn scheervlucht ontdekt door de Catalina Sky Survey.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

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Op woensdag 11 november 2009 22:38 schreef ExperimentalFrentalMental het volgende:
Meer dan 150 planetaria, musea en scholen in de VS hebben een ongeveer 1 bij 2 meter grote afdruk van de foto gekregen.

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Op zondag 15 november 2009 18:32 schreef sander89 het volgende:
Is niet helemaal precies in het zelfde straatje, maar heb weer een topic geopend want morgen word de Space Shuttle gelanceerd.

Space Shuttlemissie STS-129 met Atlantis

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^{SARA was built jointly by scientific groups
from Sweden, India, Japan and Switzerland.}

After confirming the presence of water on the lunar surface, India's Chandrayaan-1 mission has, for the first time, discovered mini-magnetosphere that would throw light on the "inventory" of Hydrogen on the moon, a top space scientist said on Friday.
SARA (Sub-keV Atom Reflecting Analyser), an instrument on board the country's first lunar orbiter, has made the discovery, Dr Anil Bhardwaj, the Principal Investigator for SARA, said.

The present concept on the inventory of Hydrogen on the moon would change now, he said, while addressing the platinum jubilee meeting of the Indian Academy Sciences here.

"The amount of inventory of Hydrogen on the lunar surface would be much different than we thought earlier. It would be lesser (than previously thought)," he said.

Bhardwaj, Head, Planetary Science Branch at ISRO's Space Physics Laboratory, Vikram Sarabhai Space Centre (VSSC) in Thiruvananthapuram, said there was a "theoretical conjecture" that probably the small magnetic field can form mini-magentosphere on moon.

SARA's findings are "first confirmation that prove that mini-magnetosphere can exist with such small magnetic field".

"This is the first step towards the confirmation of a theoretical suggestion that mini-magnetosphere can be produced," he said.

Bhardwaj said the findings on mini-magnetosphere are under submission and would be published in scientific journal shortly.

SARA has also for the first time detected ion fluxes on the "night side" of Moon. "Moon is a huge source of energetic neutral hydrogen atoms. 15-20 per cent of the impinging solar wind protons (on the lunar surface) are reflected back as neutrals," Bhardwaj said.

"The amount of hydrogen which is being implanted on the lunar surface is reduced (as one out of every five protons incoming from the solar wind rebounds from the moon's surface). You have less amount of hydrogen getting absorbed on the lunar surface," he said.

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Op zaterdag 21 november 2009 00:55 schreef ExperimentalFrentalMental het volgende:
19-11-2009

Omhulsel zonnestelsel is niet komeetvormig

[ afbeelding ]

Ons zonnestelsel lijkt niet zo zeer op een 'komeet', als wel op een 'rat die door een slang wordt opgeslokt'. Deze nogal cryptische conclusie trekken Amerikaanse onderzoekers uit gegevens die zijn verzameld door de ruimtesonde Cassini, die rond de planeet Saturnus cirkelt.

Door deeltjes uit de verre buitengebieden van het zonnestelsel te detecteren, heeft Cassini een beter beeld gegeven van de zogeheten heliosfeer: het buitenste omhulsel van het zonnestelsel, waar de zonnewind de overheersende stroom van deeltjes is. Daarbuiten bevindt zich het ijle gas en de magnetische velden van het interstellaire medium, waar het zonnestelsel, met heliosfeer en al, met grote snelheid doorheen beweegt.

Modelberekeningen lieten zien dat de heliosfeer een beetje komeetvormig zou moeten zijn, met een kop die zich een weg baant door het interstellaire medium en een staart aan de achterkant. Het lijkt er nu echter op dat dit beeld moet worden bijgesteld.

Blijkbaar is de heliosfeer zo robuust, dat hij vrijwel bolvormig blijft. Waar het zonnestelsel langskomt, wijken de magnetische velden van de interstellaire ruimte respectvol uiteen, om deze bol door te laten. Als het zonnestelsel eenmaal gepasseerd is, sluiten de magnetische gelederen weer.

© Eddy Echternach (www.astronieuws.nl)

(allesoversterrenkunde)

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Op dinsdag 24 november 2009 08:37 schreef ExperimentalFrentalMental het volgende:
23-11-2009

Donker stelsel koerst recht op het melkwegstelsel

[ afbeelding ]

In 1963 werd een grote wolk waterstofgas, Smith's cloud genoemd, ontdekt in de buurt van onze melkweg. In januari 2008 verscheen er een publicatie in NewScientist dat Smith's cloud zich in de richting van ons melkwegstelsel beweegt. Nadere studie toont aan dat de wolk een bijzonder fenomeen laat zien.

Met behulp van radio-astronomie (de Green Bank Telescope in de VS) heeft men Smith’s cloud nader bestudeerd en gedetailleerd in beeld gebracht (zie onderstaande afbeelding). De omvang van deze gaswolk is circa 11.000 lichtjaar lang en 2500 lichtjaar breed. De totale massa werd geschat op circa 1.000.000 zonnemassa’s.

[ afbeelding ]
Smith's Cloud

De gaswolk beweegt zich naar het melkwegstelsel toe met een snelheid van circa 240km/s en "het front" van de gaswolk staat op dit moment op een afstand van circa 8000 lichtjaar verwijdert van de buitenrand van ons melkwegstelsel. Met welke snelheid de gaswolk ons melkwegstelsel zal raken, is nog onzeker omdat ons melkwegstelsel gehuld is in een "eigen" gaswolk.

De gevolgen van de komende botsing van de gaswolk met het melkwegstelsel zal zichtbaar zijn in de vorm van plotselinge hevige stervorming (waterstofsterren) die vermoedelijk een miljoen jaar later de eerste supernova’s zullen gaan opleveren. Gebeurtenissen die een direct gevaar zullen opleveren voor de bestaande sterren met planeten binnen ons melkwegstelsel. In de onderstaande afbeelding is te zien vanuit welke hoek Smith’s gaswolk het melkwegstelsel nadert.

[ afbeelding ]
Smith's Cloud ten opzichte van ons melkwegstelsel.

Tot dusver geeft de bovenstaande informatie geen aanleiding tot verbazing. Het schetst een fenomeen - een grote gaswolk die aangetrokken wordt door de massa van ons melkwegstelsel - en de gegevens geven geen aanleiding tot verwondering.

Op 22-11-09 kwam NewScientist met een vervolg op het vorige artikel. Nieuw theoretisch onderzoek heeft aan het licht gebracht dat de omvang en de massa van de gaswolk aanleiding geven om het fenomeen binnen de categorie "dwergstelsels" te plaatsen ondanks het feit dat de gaswolk geen zichtbare sterren bevat. Op basis van de omvang van de gaswolk wordt verondersteld dat deze donkere materie moet bevatten en het restant is van een eerdere botsing van een dwergstelsel met ons melkwegstelsel, zo’n 70 miljoen jaar geleden. Verwacht wordt dat de komende botsing over 30 miljoen jaar het einde zal betekenen van deze gaswolk als een "zelfstandig" voortbewegend object.

En het verwonderlijke? De interstellaire ruimte en de halo van ons melkwegstelsel bevat donkere materie, Smith’s cloud bevat ook donkere materie en toont zich als een komeet die de zon nadert. Maar de heliosfeer van de zon in de vorm van de zich verplaatsende zonnewind blijft bolvormig. En dat terwijl wij binnen ons zonnestelsel geen indicatie hebben dat de zon "het centrum"is van een bulk donkere materie. Het raadsel rond de donkere materie wordt met het toenemen van waarnemingsgegevens van ruimtelijke objecten alleen maar groter.

(Astrostart)

quote:

Op dinsdag 24 november 2009 11:24 schreef Bensel het volgende:

[..]

even een vraagje over donkere materie: donkere materie is toch materie, wat zelf geen licht uitstraalt? Ik neem aan dat een planeet/planetoide/meteoroide ook onder donkere materie vallen, en zaken als stofdeeltjes (die geen licht uitstralen ook) Met andere woorden, de materie die niet zonder directe belichting te zien valt.

ik heb het idee namelijk dat men af en toe wel heel mysterieus doet over donkere materie. Donkere energie kan ik me wat bij voorstellen, aangezien we geen idee hebben hoe dat eruit zou moeten zien.