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Sonntag, 14. August 2016 - 22:00 Uhr

Raumfahrt - Start von Falcon-9 mit JCSAT-16 und Amos-6 Satelliten

5.08.2016 

SpaceX Falcon 9 rockets preparing for JCSAT-16 and Amos-6 launches

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SpaceX is lining up its next two missions, with Falcon 9 hardware currently in pre-launch preparations for launch. In Florida, the Falcon 9 tasked with the JCSAT-16 launch is preparing for a Static Fire test on August 10, while at SpaceX’s test center in Texas, the Amos-6 first stage is on the stand ready for its own engine firing ahead of shipping to the Cape.

JCSAT-16:

SpaceX’s next launch is currently scheduled for August 14, with liftoff from Cape Canaveral’s SLC-40 targeting a two hour launch window that opens at 01:26 local time.

The JCSAT-16 spacecraft will be operated by Sky Perfect JSAT Corporation, a Japanese telecommunications company formed in 2008 through the merger of Sky Perfect Communications, JSAT Corporation and Space Communications Corporation.

Space Systems/Loral constructed the satellite, which is based on the SSL-1300 bus.

A fleet of eight JCSAT spacecraft have been launched by numerous rockets, ranging from Sea Launch’s Zenit 3SLILS Proton-M and more recently Arianespace’s Ariane 5 that lofted the JCSAT-13 satellite from Kourou in May, 2012 – sharing the ride uphill with the VINASAT-2 satellite.

The Japanese company then opted to deal with SpaceX for the first time, with the contract award for the launch of its JCSAT-14 spacecraft.

That spacecraft is tasked with replacing JCSAT-2A, providing coverage to Asia, Russia, Oceania and the Pacific Islands.

With 26 optimized C-band transponders and 18 Ku-Band transponders, the satellite is being used to extend JCSAT’s geographical footprint and “address fast-growing mobility markets across the Asia-Pacific region,” per the company’s ambitions.

The May launch of JCSAT-14 to its Geostationary Transfer Orbit (GTO) was successful and included the Falcon 9 first stage concluding its flight by landing on the deck of the SpaceX drone ship “Of Course I Still Love You”.

The follow-on mission with JCSAT-16 will be a near-repeat of the May mission, with the SSL-1300 spacecraft again sporting twenty-six C-band and 18 Ku-band transponders and heading to GTO. Its operator is classing this spacecraft as an on-orbit spare.

2016-08-04-143300Preparations for the launch saw the first stage, F9-S1-0028, departing its Hawthorne birthplace for a trip to SpaceX’s McGregor test center in Texas.

It was fired up on the test stand last month to validate its propulsion systems were in good working order.

It has since arrived at Cape Canaveral and will undergo a dress rehearsal on the SLC-40 launch pad, culminating in a Static Fire of its Merlin 1D engines for a couple of seconds. SpaceX is currently aiming for an August 10 test, per L2 KSC/Cape schedules.

2016-08-04-174112The departure of F9-S1-0028 from McGregor freed up the test stand for testing of the returned JCSAT-14 booster (F9-S1-0024).

Despite suffering “max damage” from its high velocity return, a major milestone in the goal of reusing returned first stages for additional missions was achieved via three full duration firings in the space of three days.

The stage has since been removed from the test stand and is being inspected to gain additional data on the condition of the booster.

*Click here for hundreds of SpaceX News Articles*

It may yet return for additional firings, given SpaceX has noted this stage is now a ground test article and won’t be reflown.

2016-08-04-235552However, the new resident of the test stand will be flown, with F9-S1-0029 preparing for its own static fire in Texas.

It was spotted on the stand late this week (L2 McGregor), although when it is due to be fired is currently unknown.

Its job will be to help launch the Amos-6 satellite late in August, or early September.

SpaceX signed the contract to launch Amos-6 on behalf of Space Communication Ltd (Spacecom) in early 2013.

The Amos-6 satellite, built by Israel Aerospace Industries (IAI), will provide communication services including direct satellite home internet for Africa, the Middle East, and Europe.

Amos-6 – to be launched into a geosynchronous transfer orbit (GTO) – will replace Amos-2, which is expected to end its service life later this year.

Quelle: NS

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Update: 13.08.2016

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SpaceX Falcon 9 to try early Sunday launch, sea landing

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looking to expand our facilities on the Space Coast to support rocket refurbishment,” said John Taylor, a SpaceX spokesman, adding that several locations are being considered.

One site known to be of interest is the former Spacehab payload processing facility at Port Canaveral, conveniently located near the dock where SpaceX offloads boosters from its ship.

This ship is the landing target for Falcon rockets launching spacecraft to high orbits, like the upcoming mission sending a satellite on its way to a perch more than 22,000 miles over the equator. Missions to lower orbits, like last month's launch of International Space Station cargo, may try to return to a landing pad at Cape Canaveral.

 

SpaceX says it hopes to re-launch a used rocket for the first time later this year, but has not yet confirmed a target date or customer.

The mission early Sunday is SpaceX’s eighth this year, the most it has flown in any calendar year. And it's the second in about three months for Tokyo-based Sky Perfect JSAT, Asia’s largest satellite operator with a fleet of 16.

SpaceX launched the JCSAT-14 satellite on May 6. The next satellite, called JCSAT-16 and also built by California-based Space Systems Loral, will start out as a backup in orbit.

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SpaceX will add a flair of excitement for those still awake at 1:26 a.m. Sunday when it launches a Falcon 9 rocket from Cape Canaveral Air Force Station.

The California-based company will launch Falcon 9 with a Japanese communications satellite from Launch Complex 40 and will attempt a ship landing in the Atlantic Ocean. Weather is 80 percent "go," according to a forecast issued by the 45th Weather Squadron on Thursday.

Here's how you can tune in:

If you're joining us for the first time, there are two parts to our coverage:

Our live chat will kick off at 12:30 a.m. Eastern time and features in-depth coverage, photos, charts and more. You can also ask the team questions and strike up a conversation.

All these elements will be available in one article available on the homepage of FloridaToday.com beginning at 12:30 a.m. We'll host SpaceX's live video stream, which begins at 1:06 a.m.

If you happen to step outside for the launch (or any launch in the future), bring your smartphone and stay tuned to live updates and video while counting down. The coverage is available at FloridaToday.com in your mobile browser and in our mobile (iOS and Android) and tablet (iOS) apps.

Quelle: Florida Today

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Update: 14.08.2016 / 11.15 MESZ

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LIVE-Frams von Falcon-9

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Quelle: SpaceX

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14.08.2016 / 22.00 MESZ

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CAPE CANAVERAL AIR FORCE STATION, Fla. -- 

The U.S. Air Force’s 45th Space Wing supported the successful SpaceX Falcon 9 JCSAT-16 launch Aug. 14, 2016, at 1:26 a.m. ET from Space Launch Complex 40 here.

 

The Falcon 9 rocket is carrying the JCSAT-16 communications satellite built by Space Systems Loral for Tokyo-based SKY Perfect JSAT Corp. JCSAT-16 will be a backup satellite for Ku-band and Ka-band communications services over the Japanese market.

 

A combined team of military, government civilians and contractors from across the 45th Space Wing supported the mission with weather forecasts, launch and range operations, security, safety and public affairs. The wing also provided its vast network of radar, telemetry and communications instrumentation to facilitate a safe launch on the Eastern Range.

 

“I am very proud of the entire Space Coast team. Their flawless work made this mission a success,” said Col. Walt Jackim, 45th Space Wing vice commander and mission Launch Decision Authority. “Assured access to space remains a difficult and challenging endeavor.  Today's launch reflects a superb collaborative effort between commercial launch providers, allied customers, and U.S. Air Force range and safety resources. The 45th Space Wing remains a proud member of the Space Coast team and we look forward to continuing our service as the 'World's Premier Gateway to Space.’”

Quelle: USAF

 

 

 

 


1328 Views

Sonntag, 14. August 2016 - 19:31 Uhr

Astronomie - Viel Lärm um nichts: Astronomen benutzen leeren Raum um das Universum zu studieren

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This simulation of the large-scale structure of the universe reveals the cosmic web of galaxies and the vast, empty regions known as voids.
Credit: Image by Nico Hamaus, Universitäts-Sternwarte München, courtesy of The Ohio State University
 
 

Researchers who are looking for new ways to probe the nature of gravity and dark energy in the universe have adopted a new strategy: looking at what's not there.

In a paper to appear in upcoming issue of Physical Review Letters, the international team of astronomers reports that they were able to achieve four times better precision in measurements of how the universe's visible matter is clustered together by studying the empty spaces in between.

Paul Sutter, study co-author and staff researcher at The Ohio State University, said that the new measurements can help bring astronomers closer to testing Einstein's general theory of relativity, which describes how gravity works.

Sutter likened the new technique to "learning more about Swiss cheese by studying the holes," and offered another analogy to explain why astronomers would be interested in the voids of space.

"Voids are empty. They're boring, right? Galaxies are like the cities of the universe, full of bright lights and activity, and voids are like the miles and miles of quiet farmland in between," Sutter explained.

"But we're looking for bits of evidence that general relativity might be wrong, and it turns out that all the activity in galaxies makes those tiny effects harder to see. It's easier to pick up on effects in the voids, where there's less distraction -- like it's easier to spot the glimmer of a firefly in a dark cornfield than in a lit-up city bustling with nightlife."

The voids, he pointed out, are only empty in the sense that they contain no normal matter. They are, in fact, full of invisible dark energy, which is causing the expansion of the universe to accelerate.

While Einstein's 1915 general theory of relativity goes a long way toward explaining gravity in the universe, Einstein couldn't have known about dark energy. That's why, today, astronomers are working to find out whether the rules of general relativity hold up in a universe dominated by it.

Sutter, in Ohio State's Department of Astronomy, worked with colleagues in Germany, France and Italy to compare computer simulations of voids in space with a portion of data from the Sloan Digital Sky Survey. The statistical analysis revealed a four-times improvement in precision in their models of matter density and the growth of cosmological structure when they took the physics of voids into account.

They were looking for tiny deviations in void behavior that conflicted with general relativity, and they found none. So Einstein's theory of gravity holds true for now. The analysis and models are publicly available online, so the researchers hope that others will use them to do further work in the future.

"Our results demonstrate that a lot of unexplored cosmological information can be found in cosmic voids," Sutter concluded. "It's truly like getting something from nothing."

Quelle: SD

 


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Sonntag, 14. August 2016 - 17:15 Uhr

Raumfahrt - Startvorbereitung für Vega-VV07 mit PerúSAT-1

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8.08.2016

Peru’s first Earth observation satellite arrives in French Guiana for its Vega launch

VA232 Arrivée PerùSat-1 à l'aéroport Fzlix Eboué le 05/08/2016

After touching down in French Guiana aboard a cargo jetliner, the protective shipping container with PerúSAT-1 is positioned via crane for its transportation by road to the Spaceport.

The PerúSAT-1 passenger for Arianespace’s next Vega mission is now in French Guiana, where payload preparations are beginning for a September liftoff from the Spaceport.

Built by Airbus Defence and Space based on its AstroBus-S platform, the spacecraft was transported from Toulouse, France – where it was produced – aboard a cargo aircraft, which touched down in French Guiana at Cayenne’s Félix Eboué Airport late last week.

Following its transfer by road to the Spaceport’s S3B payload preparation facility, PerúSAT-1 is in position for final checkout and integration with Vega before lifting off from the South American launch facility – where Arianespace operates its family of light-lift Vega, medium-weight Soyuz and heavy-lift Ariane 5 vehicles.

PerúSAT-1 – which is the first Earth observation satellite for Peru – was ordered by the country’s government for its national space agency, CONIDA (La Comisi&oa

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PerúSAT-1 is prepared for Arianespace’s next Vega launch from the Spaceport

VV07 Destockage PeruSat-1 au S3B, le 05/08/2016

PerúSAT-1 is removed from its protective shipping container during activity inside the Spaceport’s S3B clean room facility. 

Peru’s initial Earth observation satellite – PerúSAT-1 – is getting a first look inside the Spaceport’s S3B clean room, where payload preparations are advancing for Arianespace’s Vega mission on September 16.

PerúSAT-1 was removed from its protective shipping container after being delivered late last week from Toulouse, France – where the spacecraft was produced – to French Guiana via cargo jetliner, then transferred by road to the Spaceport.

Built by Airbus Defence and Space based on its AstroBus-S platform, PerúSAT-1 incorporates an advanced silicon carbide instrument system that is designed to deliver imagery at a 70-cm. resolution over a lifetime of 10 years. It was ordered by the Peruvian government for operation by the country’s national space agency, CONIDA (La Comisión Nacional de Investigación y Desarrollo Aeroespacial).

The Vega launch with PerúSAT-1 is designated VV07 in Arianespace’s numbering system and will follow the company’s upcoming Ariane 5 flight at the service of Intelsat – which is scheduled for liftoff on August 24.

Flight VV07 will mark the light-lift Vega’s seventh launch overall, and the first this year from Europe’s Spaceport – which already has seen three successful heavy-lift Ariane 5 missions, as well as two with the medium-weight Soyuz vehicle.

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Update: 14.08.2016

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PerúSAT-1 is checked “fit” for Arianespace’s next Vega launch

A pioneering Earth observation satellite for Peru has made initial contact with launcher hardware as PerúSAT-1 completes its fit-check in preparation for a September 16 liftoff from French Guiana aboard an Arianespace Vega launch vehicle.

PerúSAT-1 is shown during the fit-check validation ahead of its Vega launch

PerúSAT-1 is lowered onto its adapter hardware for the Vega launcher during fit-check activity at the Spaceport.

The fit-check is a regular milestone during mission preparations at Arianespace’s Spaceport launch site in French Guiana, verifying the physical matchup of a payload with the hardware that serves as its interface when integrated on the launcher. Once the step is achieved, a payload is cleared to continue the pre-launch processing.

For PerúSAT-1, this activity was performed in the Spaceport’s S3B satellite preparation facility during the weekend, following its delivery last week from Europe to French Guiana.

PerúSAT-1 is based on a compact AstroBus-S spacecraft platform produced by Airbus Defence and Space, which combines the advantages of a low-mass system with the performance of a larger Earth observation platform.

Imaging resolution of 70 cm. for Peru’s first Earth observation satellite

Ordered in 2014 by the Peruvian government for its national space agency, CONIDA, PerúSAT-1 is equipped with a revolutionary silicon carbide optical instrument system to image Earth at 70 cm. resolution, and will serve as the country’s first Earth observation satellite.

The Vega mission with PerúSAT-1 is designated Flight VV07 in Arianespace’s launcher family numbering system, signifying the light-lift vehicle’s seventh launch overall, and its first this year from Europe’s Spaceport.

So far during 2016, Arianespace has performed three successful heavy-lift Ariane 5 missions, as well as two utilizing the medium-weight Soyuz vehicle – with another Ariane 5 launch in preparation for liftoff on August 24.

Quelle: arianespace


1294 Views

Sonntag, 14. August 2016 - 16:00 Uhr

Astronomie - Ein Sternenlabor im Schützen

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Der Bereich um die wenigen blauen Sterne im oberen linken Teil dieses riesigen neuen 615 Megapixel großen ESO-Bilds stellt die perfekte kosmische Umgebung dar, um das Leben und Sterben von Sternen zu untersuchen: In dem Messier 18 genannten Sternhaufen finden sich viele Sterne, die einst aus derselben massereichen Wolke aus Gas und Staub entstanden sind. Aufgenommen wurde das Bild, das auch rote Wolken leuchtenden Wasserstoffs und dunkle Filamente aus Staub beinhaltet, mit dem VLT Survey Telescope (VST) am Paranal-Observatorium der ESO in Chile.

Messier 18 wurde 1764 von Charles Messier – nach dem die Messier-Objekte benannt sind – während seiner Suche nach kometenartigen Objekten entdeckt und katalogisiert [1]. Messier 18 liegt innerhalb der Milchstraße, schätzungsweise 4600 Lichtjahre von uns entfernt im Sternbild Sagittarius (der Schütze), und besteht aus vielen Geschwistersternen, die gravitativ nur schwach aneinander gebunden sind, so dass er als offener Sternhaufen bezeichnet wird.

Es gibt über 1000 bekannte offene Sternhaufen in der Milchstraße, die sich hinsichtlich ihrer Eigenschaften wie Größe und Alter zum Teil stark unterscheiden. Da alle Sterne in einem Haufen aus derselben Materie entstanden sind, liefern sie Astronomen wichtige Informationen darüber, wie Sterne entstehen, sich entwickeln und sterben.

Aus der blauen und weißen Farbe der Sternpopulation in Messier 18 können die Forscher schließen, dass die Sterne in dem Haufen sehr jung sind, vermutlich nur etwa 30 Millionen Jahre. Da die einzigen Unterschiede zwischen den Sternen ihre unterschiedlichen Massen sind und sie dieselbe chemische Zusammensetzung sowie Entfernung zur Erde besitzen, kann man sie als Geschwister betrachten. Insofern eignen sich solche Sternhaufen gut, um die gängigen Theorien über Sternentstehung und -entwicklung zu verbessern.

Astronomen wissen heutzutage, dass sich die meisten Sterne in Sternhaufen gebildet haben und alle Sterne eines Haufens in derselben Gaswolke geboren wurden, die vorher aufgrund ihrer eigenen Anziehungskraft in sich zusammengefallen war. Die Wolke aus übriggebliebenem Gas und Staub – auch Molekülwolke genannt – die die neugeborenen Sterne umschließt, wird oftmals von den starken Sternwinden weggeblasen, sodass die gravitative Bindung, die dafür sorgt, dass die Sterne sich nicht voneinander entfernen, abnimmt. Mit der Zeit gehen durch Wechselwirkungen mit anderen benachbarten Sternen oder massereichen Gaswolken immer mehr Geschwistersterne verloren, wie es auch auf diesem Bild zu erkennen ist. Unser eigener Stern, die Sonne, war mit großer Wahrscheinlichkeit zu Beginn ihres Lebens auch Teil eines Sternhaufens, der Messier 18 sehr ähnlich gewesen sein dürfte, bis die Begleitsterne der Sonne allmählich in der Milchstraße verstreut wurden.

Die dunklen Bereiche, die sich durch das Bild ziehen, sind dunstige Filamente aus kosmischem Staub, die das Licht der dahinter liegenden Sterne blockieren. Die lichtschwachen rötlichen Wolken, die sich vom Hintergrund absetzen und zwischen den Sternen hindurchschlängeln, bestehen aus ionisiertem Wasserstoffgas. Das Gas leuchtet, da junge, extrem heiße Sterne wie diese intensives ultraviolettes Licht emittieren, welches die Elektronen aus dem umgebenden Gas löst und das schwache Leuchten verursacht, das man in diesem Bild sieht. Unter den entsprechenden Bedingungen könnte diese Materie eines Tages in sich zusammenfallen und der Milchstraße sogar eine neue Generation an Sternen liefern – ein Sternentstehungsprozess, der unbegrenzt weiter gehen kann (eso1535).

Dieses riesige 30 577 x 20 108 Pixel große Bild wurde mit der OmegaCAM-Kamera aufgenommen, die am VLT Survey Telescope (VST) am Paranal-Observatorium der ESO in Chile angebracht ist.

Endnoten

[1] Messier 18 ist als NGC 6613 auch im New General Catalogue aufgeführt.

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Diese Aufsuchkarte zeigt das Sternbild Schütze. Unter den vielen Sternhaufen in diesem Teil der Milchstraße findet sich Messier 18, ein helle Gruppe Sterne unweit des Omeganebels (Messier 17). Auf dieser Karte sind die meisten Sterne eingezeichnet, die in einer dunklen, klaren Nacht mit bloßem Auge sichtbar sind.

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Die wenigen hellen Sterne in der Mitte dieser Weitfeldaufnahme bilden Messier 18, einen offenen Sternhaufen, dessen Sterne alle aus der derselben massereichen Wolke aus Gas und Staub entstanden sind. Dieses Bild, das oben auch Teile des hellen Omeganebels (Messier 17) zeigt, wurde aus Bildern des Digitized Sky Survey 2 erstellt.

Quelle: ESO

 


1091 Views

Sonntag, 14. August 2016 - 12:00 Uhr

Astronomie - Studie: METHANE GEFÜLLTE CANYONS LINE auf Titan-Oberfläche

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Liquid methane and ethane flowing through Vid Flumina, a 400-kilometer long river often compared to Earth’s Nile River, is fed by canyon channels running hundreds of meters deep.
Credit: NASA, JPL-Caltech, Agenzia Spaziale Italiana.

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WASHINGTON, DC — Liquid methane-filled canyons hundreds of meters deep with walls as steep as ski slopes etch the surface of Titan, researchers report in a new study. The new findings provide the first direct evidence of these features on Saturn’s largest moon, and could give scientists insights into Titan’s origins and similar geologic processes on Earth, according to the study’s authors.

New Cassini radar observations of Titan’s north pole depict cavernous gorges a little less than a kilometer (less than half a mile) wide with walls up to 570 meters (1870 feet) tall — about 30 meters (98 feet) higher than New York’s Freedom Tower. The eight canyons branch off from Vid Flumina, a more than 400-kilometer (249-mile) long river flowing into Titan’s second-largest sea, Ligeia Mare. The new data confirm the canyons are filled with flowing methane — a feature researchers had suspected but not directly observed, according to the study’s authors.

The new findings suggest the canyons were likely carved by liquid methane draining into Vid Flumina, a process similar to the carving of river gorges on Earth, according to the study’s authors. The new research could help scientists better understand these geological processes, they said.

“These are processes we need to totally understand because they can shed deeper light on our own planet,” said Valerio Poggiali, a planetary scientist at the La Sapienza University of Rome, Italy, and lead author of the new study published in Geophysical Research Letters, a journal of the American Geophysical Union.

NASA’s Cassini spacecraft, launched in 1997, has granted scientists their first up-close look at Saturn, its rings and moons. Cassini’s observations of Titan — with its many Earth-like features — have given scientists a glimpse of what our planet might have been like millions of years ago, according to NASA.

Scientists first observed Titan’s hydrocarbon seas in 2006 during one of Cassini’s early flybys. Six years later the spacecraft spied Vid Flumina and its branching channels. Researchers suspected those channels, some of which appeared canyon-like, were filled with flowing methane. Other clues like icy pebbles rounded by river-flow affirmed their suspicions, but they lacked direct evidence the channels were liquid-filled — until now.

“What we didn’t know was whether some channels still contained liquids, i.e., whether these rivers of methane were still flowing,” said Rosaly Lopes, a planetary geologist at NASA’s Jet Propulsion Laboratory in Pasadena, California, who is also mapping Titan’s surface but was not connected to the study. “[Poggiali’s] work is what nailed that.”

Methane rivers and seas

The researchers used Cassini’s instruments to bounce radio signals off Titan’s surface. The returned signals defined the moon’s surface features, allowing the researchers to discern rocky outcrops from smooth liquid.

White circles denote areas pinged by Cassini's radar. Credit: NASA JPL.

White circles denote areas pinged by Cassini’s radar. Credit: NASA JPL.

The signals show the canyons’ walls rise at least as sharply as 40 degrees. Earth shares a similar slope in one of its most dangerous ski runs: Corbet’s Coulier in Wyoming. On Earth, skiers plunge down the lofty mountain and glide over snow, but a skier on Titan would tumble hundreds of meters down the canyon walls and splash into a methane river. Although the images showed the canyons were filled with liquid methane, they could not measure the depth of the liquid, which could run shallow or deep, according to the new study.

 A view of Titan’s northern pole reveals many hydrocarbon lakes and seas. Titan is the only other celes-tial body, in addition to Earth, where erosion actively etches its surface. Credit: NASA, JPL-Caltech, ASI, and USGS.

A view of Titan’s northern pole reveals many hydrocarbon lakes and seas. Titan is the only other celes-tial body, in addition to Earth, where erosion actively etches its surface.
Credit: NASA, JPL-Caltech, ASI, and USGS.

The study’s authors draw comparisons between Titan’s canyons, and Arizona and Utah’s Lake Powell and the Nile River gorge. Both feature canyons and valleys etched by erosion from flowing liquid. The deep cuts in Titan’s landscape indicate the process that created them occurred over multiple extended periods, though the age of that process remains uncertain. They could have been created by uplift of the terrain or changes in sea level, or both, according to the study’s authors.

Titan is the only planetary body in our solar system, other than Earth, to have a surface actively eroding on a large scale, according to Lopes.

“We have seen some canyons elsewhere, such as Vallis Marineris on Mars,” Lopes said. “However, on Titan, this study shows evidence that some canyons are still filled with liquid and presumably in the process of carving canyons.”

Studying the geologic processes on Titan can help researchers tease apart the moon’s origins and conditions on early Earth. Titan allows scientists to see how these processes change under varying conditions, like changes in temperature, according to Lopes.

“On Earth we can’t vary the conditions like surface temperature and atmospheric density to see how geologic processes would behave,” Lopes said. But by turning to Titan, scientists can see how familiar processes could change when those conditions are altered, she added.

“Although the term is overused, Titan is really a ‘natural laboratory’ for understanding geological processes,” Lopes said.

Lopes said many more small canyons may line Titan’s surface, possibly hidden just below the resolution of Cassini’s instruments. Future missions could reveal those and other features, which may further color our understanding of Titan’s origins, she said.

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The American Geophysical Union is dedicated to advancing the Earth and space sciences for the benefit of humanity through its scholarly publications, conferences, and outreach programs. AGU is a not-for-profit, professional, scientific organization representing more than 60,000 members in 139 countries. Join the conversation on FacebookTwitterYouTube, and our other social media channels.

Quelle: AGU

 

 

1199 Views

Samstag, 13. August 2016 - 08:49 Uhr

Astronomie - Perseiden Nachlese

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Nach dem hier bei mir die Perseiden-Show absolut ins "Regen"-Wasser gefallen ist, hier ein Blick nach England und Österreich welche eine Vielzahl von hellen Perseiden beobachten konnten:

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Aufgenommen über England, nachfolgende Aufnahmen von der Sternwarte Gahberg/Österreich:

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Freitag, 12. August 2016 - 21:00 Uhr

Astronomie - Zwerggalaxie DDO 68 und DDO 68C

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This visible-light image taken with the Large Binocular Telescope shows dwarf galaxy DDO 68, which lies in a comparatively "empty" region of space 39 million light-years from Earth, and one of its companion objects, DDO 68 C. The scale bar indicates a distance of 3.6 kiloparsecs, or just under 12,000 light-years. Image courtesy Francesca Annibali/INAF.

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Even a dwarf galaxy with very low mass is capable of accreting smaller nearby galaxies, according to an international team of astronomers led by Francesca Annibali of INAF, the Italian National Institute for Astrophysics. This result has been achieved thanks to observations of the region surrounding the dwarf galaxy DDO 68, which has a total stellar mass of only 100 million solar masses, roughly one thousandth of our Milky Way.

Within the scenario of hierarchical galaxy formation, theoretical models predict that galaxies form by successive mergers of smaller systems at all scales. However, until now, direct observational evidence confirming these predictions was available only for massive galaxies and their smaller companions.

In the new study, Annibali and collaborators took advantage of the sensitivity and the large field of view of the Large Binocular Telescope, or LBT, located on Mt. Graham in southeastern Arizona (U.S.). The team discovered that DDO 68, a dwarf galaxy located in an isolated region of space defined as a "void," is actually surrounded by a number of smaller satellite galaxies, and is accreting them.

"In a way, what we saw reminded us of a quote by Jonathan Swift," Annibali said. "'So, naturalists observe, a flea has smaller fleas that on him prey; and these have smaller still to bite 'em; and so proceed ad infinitum.' It turns out that even the smallest of galaxies feed on companions that are even smaller, and so our paper bears that quote in its title."

DDO 68 is one of three known least evolved galaxies among those that still form stars, with a chemical composition not much different from that resulting from the Big Bang. Scientists had already thought that its extremely irregular morphology - with a long tail hosting both stars and gas - could be due to tidal effects resulting from gravitational interactions with other bodies. Incidentally, a candidate companion - possibly another small galaxy or a gas cloud - was spotted at a relatively large distance two years ago by a team led by John Cannon of Macalester College in Minnesota.

"When we analyzed our Hubble Space Telescope images, we detected an anomalous protuberance off DDO 68's main body," said Francesca Annibali, a postdoctoral fellow/researcher at the INAF - Astronomical Observatory in Bologna, Italy.

"We thought that only LBT with its two 8.4 meter primary mirrors could have the power and the field of view necessary to prove, or disprove, the presence of a stream and other accreting satellites."

LBT's wide and deep images revealed that DDO 68 not only has its well known long tail, but also another small, incoming stream and a few other star and gas companions that most likely are satellites whose ultimate fate is to be accreted.

The stream and satellites probably have masses - about 100,000 solar masses - similar to, or even lower than, those of the ultra-faint Milky Way satellites, the least luminous and smallest galaxies known so far, believed to be the closest local analogs of the first galaxies.

"Our colleagues, Luca Ciotti and Carlo Nipoti of the Physics and Astronomy Department at the Bologna University, have computed numerical dynamical models of DDO 68's system that reproduce very well the observed configuration of the 'flea with its smaller fleas,'" Annibali pointed out.

"This is the first evidence of a stellar stream around an isolated dwarf galaxy of only a hundred million solar masses, and the observational proof that hierarchical galaxy formation processes work also at the smallest scales."

"In other words, not only massive bodies are able to cannibalize the smaller ones that happen to lie in their surroundings, but the same appetite and digestion capabilities can be found in the smaller ones," added Monica Tosi, INAF astronomer and member of Annibali's team.

Dwarf galaxies with active star formation are important in helping scientists understand the formation and evolution of galaxies in general.

Of those, galaxies that are extremely poor in metals, such as DDO 68, are even more interesting, because in spite of having formed stars for many billions of years, they haven't been able to retain the chemical elements produced by nuclear fusion inside stars. Most likely they have lost their metals via ejection into the surrounding medium through galactic winds triggered by supernova explosions.

"It is very interesting to discover that a system whose gravitational potential is too low to retain ejecta from supernovae is still capable of attracting and accreting smaller galaxies," Tosi said. "Specific dynamical and hydrodynamical studies are necessary to understand what main mechanisms are at play here."

"The results achieved with DDO 68 show the high discovery power of wide-field instrumentation mounted on 8- to 10-meter class telescopes for future projects devoted to the search of substructures around isolated dwarf galaxies," she added. "It also emphasizes the importance of combining deep observations with theoretical studies on the evolution and the dynamics of both stars and gas in the galaxies we study."

Quelle: SD

 


1188 Views

Freitag, 12. August 2016 - 13:00 Uhr

Astronomie - Genesis in einem Gefäß: Wie chemische Gärten uns fremdes Leben zeigt

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Chimneys of iron hydroxide (left) and iron sulphide (right) precipitate out of solution when alkaline fluids feed into these mimics of early Earth oceans

Left: Laurie Barge; Right: Ryan Cameron

In a collection of glass jars at NASA’s Jet Propulsion Lab, Michael Russell’s team is trying to recreate the moment before life on Earth came into being.

The jars are filled with seawater and stirred with a blend of chemicals designed to match the seas of Earth as they were 4 billion years ago. A syringe at the base of each jar pumps in another concoction – crafted to approximate the alkaline fluid emitted by hydrothermal vents on the sea floor. Where the two fluids come together, minerals precipitate out to form a delicate tower reminiscent of the crystal gardens made with toy chemistry kits.

Russell has spent the past three decades working on a theory that life began on Earth, and perhaps elsewhere in the solar system, in places like this. Now, with these miniature crystal gardens, he is putting that idea to the test.

Ocean or pool?

A competing theory holds that life started in shallow freshwater pools over a hydrothermal field, like those in modern-day Iceland. The pools swelled when rain fell, but when they evaporated, the organic molecules in them became more concentrated, forming films like cell membranes, or joining into longer chains like strands of RNA.

 

In this account, lifelike structures can easily come together – and lab experiments have backed that up. For Russell, however, easy assembly isn’t enough. The key is to find chemical imbalances that could power a metabolism. And for that, he says, the best place to look is at a particular kind of hydrothermal vent, gently bubbling away on the ancient sea floor

Russell’s theory is attractive because it takes account of how life exploits energy sources. The process involves pumping positively charged hydrogen ions, called protons, across a membrane.

Pumping brings more protons to one side, causing an imbalance. But when they cross back the other way, an enzyme called ATP synthase steals energy from the flow and stores it in molecules of ATP.

Proton power

Living cells thrive by exploiting similar imbalances in nature – of protons, and also electrons, which are exchanged in chemical reactions between oxidants and reductants. “We would say evolution is merely a search engine for similar disequilibria,” says Russell.

So how could life harvest these chemical imbalances before soft, permeable membranes existed to keep the ingredients organised?

According to Russell, the answer starts with water percolating down into the rocky mantle, where it reacts with minerals to produce an upwelling of alkaline, hydrogen-rich effluent – a process called serpentinisation. The fluids react with relatively acidic seawater to produce mineral structures full of tiny pores, where hydrogen and carbon dioxide come together to form simple molecules.

And here’s where the energy comes in. The difference in pH – basically a measure of proton concentration – between the seawater and effluent also gives rise to a proton gradient across the walls of these pores, creating electrochemical potential that molecules inside the chambers could tap.

 

When Russell first came up with the idea, we did not know of any such vents. In 2000, however, we discovered the Lost City at the bottom of the Atlantic – a system of alkaline vents with mineral towers supporting microbes and other forms of life.

Chemical gardens

Russell has since embellished his theory, adding that a mineral called green rustwhich can form in vent chimneys, can exploit the flow of protons at a vent in much the same way as ATP synthase. He argues that the built-in proton gradient would be enough for a primitive organism to feed on.

Later, it could have brought with it other enzyme-like minerals from the chimney walls, allowing it to establish a proton gradient on the go. “Life had to figure out how to make its own vent, eventually,” says Laurie Barge, one of Russell’s collaborators.

More recently, Russell, Barge, and their teams have begun to test their ideas experimentally by growing their own vents in jars. Their chemical gardens at the Jet Propulsion Lab in Pasadena, California, have already confirmed that hydrothermal vents can provide that all-important proton gradient, measured as electrical potential between the inside and outside of a chimney.

“If you grow it around an electrode, you can see the voltage appear as the chimney starts growing,” Barge says. Indeed, hooking several vents together produces enough juice to power a light bulb.

Now they are trying to figure out how organic molecules can assemble and evolve in the pores of chimneys. “It’s kind of like a mineral sponge, which will keep anything in there and concentrate it,” Barge says. In 2015, Russell and his collaborators showed that a vent surrounded by an approximation of Earth’s early ocean could link RNA molecules into a two-part strand, and Barge says they will soon release more results.

Other worldly implications

A recent analysis suggests that the last common ancestor of all life on Earth had the genes to feed on a proton gradient but not the genes required to make its own, lending support to Russell’s theory.

Even so, its supporters still have to provide firm evidence that larger molecules and membranes can be synthesised at alkaline hydrothermal vents, says David Deamer of the University of California, Santa Cruz, who is a leading proponent of the idea that life evolved in evaporating pools instead. “Until they’re able to show that, they really don’t have evidence to substantiate the claim that life can begin under these conditions,” says Deamer.

If Russell is right, then our view of life would be transformed: rather than some lucky accident, life starts to looks like an unavoidable consequence of the thermodynamic and chemical conditions in the oceans of early Earth. And the implications of these experiments go beyond the origins of life on our own planet.

We now know that distant moons like Europa, which orbits Jupiter, and Enceladus, which circles Saturn, house vast subsurface oceans that some astrobiologists suspect host hydrothermal vents akin to Lost City. NASA will send a probe to Europa to find out in the next decade, and plans are afoot for a similar mission to Enceladus – where there are hints that the sea floor could be bubbling with hydrogen-rich fluids.  

If so, the odds of finding life out there would be slashed. At the very least, Russell is convinced that wherever these alkaline vents exist, mineral chimneys will form, and the molecular precursors of life could organise and enjoy ready access to the energy they need to grow and replicate. “It’s extremely likely – almost 100 per cent, we would say – that the same kind of processes happen on any wet rocky world,” he says.

Quelle: NewScientist


1111 Views

Freitag, 12. August 2016 - 12:00 Uhr

Raumfahrt - NASA Theorie: Ist PCOS die Ursache für nachlassen der Sehkraft von Astronauten im All?

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Imagine being on a mission to Mars, and suddenly finding yourself unable to read the ship’s instruction manual. Sounds like a nightmare, but in the past few years, the scientists who study astronauts have made a startling discovery: Some of them experience bizarre, unexplained vision problems when they fly into space. Their eyesight might get muddier, and they might start to need glasses where they didn’t before. An eye exam could reveal cotton wool spots, or an unexplained swelling or a flattening at the back of their eyeballs.

A decade ago, nobody realized that vision loss in space was even an issue; it wasn’t on the radar at all. Now, as we’ve flown more humans into space, for longer and longer stretches of time, it’s become clear just how serious of a problem this is. Many scientists now consider vision loss and other related changes to be the number one risk of spaceflight. 

The trouble is, while there are plenty of theories, nobody has a solid explanation for why it happens—and only to some astronauts. Right now, it’s impossible to know for sure who will be affected before they fly.

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NASA astronaut Michael Hopkins, performs ultrasound eye imaging in the Columbus laboratory of the International Space Station. European Space Agency astronaut Luca Parmitano assists Hopkins. Image: NASA

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One NASA researcher is staking his reputation on an admittedly far-out hypothesis. If he’s right, it could unravel the mystery, and pave the way for new treatments to ensure that astronauts of the future don’t struggle this way. It might also have important implications for a group of patients here on Earth, who don’t always have a lot of options today.

But the idea is pretty wacky. “When we first came up with this, we were very reluctant to say it out loud. Just because it’s that big of a leap,” Scott M. Smith, who’s led the Nutritional Biochemistry Laboratory at NASA’s Johnson Space Center for over 20 years, told me in an interview. (Smith has been studying vision problems in astronauts for the last six years.) “The more we poke at it, the more pieces of the puzzle keep falling in line.” 

Smith now speculates that astronauts who develop vision problems in space might have an underlying health condition, one that’s actually fairly common on Earth: Polycystic ovary syndrome, or PCOS, which affects about one in ten women, according to one estimate, and lasts over a lifetime. He’s about to start a clinical trial, with the Mayo Clinic in Minnesota, to study this more.

There’s just one problem, and it’s a big one: PCOS, of course, only affects women. And all the astronauts who’ve reported troubles with their eyesight in space, so far at least, have been men. 

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Astronaut Robert Thirsk lived aboard the International Space Station in 2009 for six months, becoming the first Canadian to do a long-duration mission. He and NASA’s Michael Barratt started noticing some changes to their eyesight. Both doctors, they performed ultrasounds on their eyeballs (there’s a machine aboard the ISS) and noticed something strange: the backs of their eyeballs had become “flattened, pushed in,” as Thirsk told me in one of our previous conversations

Thirsk became farsighted, and it persisted after he got home, although his vision has slowly improved since then. Other astronauts have reported the same.

NASA astronaut John Phillips, who flew in 2005, recently described to the Washington Post how his vision dropped from 20/20 to 20/100 after six months on the Station. While his vision has improved, he still needs glasses today.

“Some [who experience vision problems] eventually go back to normal,” Smith told me. “Others have been followed for years, and they don’t go back.” He hesitated to even estimate how many astronauts are affected, because the data is so new that we don’t know what’s typical. “There’s a debate over that,” he said. “I don’t give out a percentage.”

Scientists are running experiments on the ISS to figure out what’s going on, and have made vision a priority for research. Eye exams are standard for astronauts before, during, and after flight. One popular hypothesis is that a shift in intracranial pressure is to blame: In zero gravity, the fluids in our bodies move upwards, and push on the optic nerve and the back of the eye. 

“Everybody is looking into the cardiovascular pathway,” Smith told me. “Our group takes a different approach.” His research is showing that PCOS patients share some surprising commonalities with this subset of astronauts. In a 2012 study, for starters, Smith described how astronauts who experience vision changes have higher levels of homocysteine in their blood (an amino acid that’s a common marker of cardiovascular disease), which is also seen in women with PCOS. But his findings now go beyond that.

Smith’s proposed link to PCOS comes out of left field. We still don’t know a lot about this mysterious syndrome, not even what causes it, although it’s likely some mix of genetics and environment. It’s diagnosed in women basically “by exclusion,” which means ruling out everything else, as Dr. Sheila Laredo, endocrinologist at Women’s College Hospital in Toronto, told me in an interview. (She isn’t involved with Smith’s work.) Doctors look for certain telltale signs, like irregular or missed periods, a surplus of male hormone, and evidence of “large, visible follicles” on the ovaries, she said.

There’s no cure, but there are ways to control it, such as by taking birth control pills to help regulate hormones. Still, patients can struggle with fertility issues and other troubles. 

Women with PCOS are often obese, but not always, Laredo said. And they tend to have insulin resistance, which can increase the risk of diabetes, she continued—which can lead to vision problems. “Cotton wool spots are related to poor diabetes control,” she said.

Still, eyesight problems are not thought to be directly associated with PCOS, Laredo told me.

When I described Smith’s hypothesis about astronauts to Laredo, who estimates that she probably treats the most PCOS patients in her clinic anywhere in Canada, she was startled. “I haven’t heard about this at all,” she said. “It hasn’t hit the PCOS literature.”

Depending on the results of the upcoming clinical trial, that may change.

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It was last summer when Smith and his small team first started wondering about a link. Preparing some research on genetic similarities in astronauts who suffer from vision issues, they were sifting through the literature, “and realized there’s a clinical population that has many of the characteristics, that are exactly like either what we’ve seen in astronauts with vision issues, or what we hypothesize exists in this group,” he said.

“The group we’re talking about is women with PCOS,” Smith added. 

Their paper was published in The FASEB Journal in January, and floats a possible link to PCOS, but almost as an afterthought, close to the end. In the paper, Smith and his team describe genetic differences relating to something called the one-carbon pathway of metabolism—a variation shared by women with PCOS. They also explain how women with PCOS, like these astronauts, have higher levels of homocysteine, altered hormone levels, a thicker retinal nerve fiber layer, intracranial hypertension, the list goes on.

“Although PCOS obviously only affects women, PCOS-type manifestations are not limited to women,” the paper says. “Evidence shows that male relatives of PCOS patients have similar symptoms, and some researchers have hypothesized that PCOS occurs in men,” it continues, adding that the polycystic ovaries that are the actual namesake of this disease could just be a “downstream effect” of other disruptions, which are shared by both genders. 

Anyway, only 80 percent of women with PCOS actually have polycystic ovaries. It’s a syndrome we still don’t understand, with a name that doesn’t accurately describe it.

“Some have suggested that men get PCOS, but are not diagnosed with it because they don’t have ovaries,” Smith told me in a follow-up email.

Only 11 percent of all humans who’ve been to space have been women

If PCOS is relatively common among women, with one-in-ten-affected, this raises another question: Why haven’t any female astronauts reported vision problems as a result of flying in space?

For one thing, all astronauts are heavily screened before they’re allowed to begin training. Women with PCOS tend to be obese, or show insulin resistance, which would likely exclude them from flying. “We speculate that this may be why we’re not seeing [vision loss] in female astronauts. They’re not being selected because tests are excluding them,” Smith said.

That, and we just haven’t flown nearly as many women into space as men. Only 11 percent of all humans who’ve been to space have been women. Maybe if more of them made it onto Station, these problems would start to crop up in women, too.

“I’d say, based on the theory, if we were to fly women with PCOS into space, they’d all develop these vision issues,” Smith said.

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At the Mayo Clinic, researchers will soon begin recruiting women to participate in a clinical trial. They’re hoping for 80 altogether, divided into four groups, including women with PCOS, with intracranial hypertension (an unexplained increased pressure in the skull, that also affects many women with PCOS, and is known to cause vision changes), and a healthy control. They’ll be collecting data and comparing it to as many astronauts as they possibly can, both male and female—already, 49 astronauts were included in the January study.

I talked to Dr. Alice Chang, an endocrinologist at the Mayo Clinic who is principal investigator of this particular trial, and working with Smith. When he approached the clinic about doing it, “it was a little embarrassing, as a PCOS researcher, that [vision changes] were not at the forefront of our minds,” she told me. Doctors screen these women for all kinds of things, from sleep apnea to pre-diabetes, but don’t necessarily look for changes in their eyesight.

Depending on what comes out of this clinical trial, maybe that will change in the future.

As for whether PCOS could affect both sexes—not just women—Chang became thoughtful. “The name of the syndrome has been misleading,” she said. “We get distracted by it.” In reality, she said, this condition is more about having an excess of testosterone-like hormone, which can impact fertility and cause the downstream effects we see in PCOS.

So, yes, it’s possible that men do experience a version of it.

Smith’s research stands to help these patients, a group he probably never imagined would benefit when he started trying to figure out the root causes of astronaut vision loss.

The PCOS patients, meanwhile, could help humans fly more safely in space. Just as scientists do bedrest studies to get an idea about what zero gravity does to our bodies, Smith said, “we feel that women with PCOS might be a matching analog for these astronauts.”

Quelle: Motherboard


1248 Views

Freitag, 12. August 2016 - 09:30 Uhr

Astronomie - NASA Klimamodell regt an, das Venus bewohnbar gewesen sein kann

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Venus may have had a shallow liquid-water ocean and habitable surface temperatures for up to 2 billion years of its early history, according to computer modeling of the planet’s ancient climate by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.

 

The findings, published this week in the journal Geophysical Research Letters, were obtained with a model similar to the type used to predict future climate change on Earth.

 

“Many of the same tools we use to model climate change on Earth can be adapted to study climates on other planets, both past and present,” said Michael Way, a researcher at GISS and the paper’s lead author. “These results show ancient Venus may have been a very different place than it is today.”  

 

Venus today is a hellish world. It has a crushing carbon dioxide atmosphere 90 times as thick as Earth’s. There is almost no water vapor. Temperatures reach 864 degrees Fahrenheit (462 degrees Celsius) at its surface.  

 

Scientists long have theorized that Venus formed out of ingredients similar to Earth’s, but followed a different evolutionary path. Measurements by NASA’s Pioneer mission to Venus in the 1980s first suggested Venus originally may have had an ocean. However, Venus is closer to the sun than Earth and receives far more sunlight. As a result, the planet’s early ocean evaporated, water-vapor molecules were broken apart by ultraviolet radiation, and hydrogen escaped to space. With no water left on the surface, carbon dioxide built up in the atmosphere, leading to a so-called runaway greenhouse effect that created present conditions.

 

Previous studies have shown that how fast a planet spins on its axis affects whether it has a habitable climate. A day on Venus is 117 Earth days. Until recently, it was assumed that a thick atmosphere like that of modern Venus was required for the planet to have today’s slow rotation rate. However, newer research has shown that a thin atmosphere like that of modern Earth could have produced the same result. That means an ancient Venus with an Earth-like atmosphere could have had the same rotation rate it has today.

 

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Observations suggest Venus may have had water oceans in its distant past. A land-ocean pattern like that above was used in a climate model to show how storm clouds could have shielded ancient Venus from strong sunlight and made the planet habitable.
Credits: NASA

Another factor that impacts a planet’s climate is topography. The GISS team postulated ancient Venus had more dry land overall than Earth, especially in the tropics. That limits the amount of water evaporated from the oceans and, as a result, the greenhouse effect by water vapor. This type of surface appears ideal for making a planet habitable; there seems to have been enough water to support abundant life, with sufficient land to reduce the planet’s sensitivity to changes from incoming sunlight.

 

Way and his GISS colleagues simulated conditions of a hypothetical early Venus with an atmosphere similar to Earth’s, a day as long as Venus’ current day, and a shallow ocean consistent with early data from the Pioneer spacecraft. The researchers added information about Venus’ topography from radar measurements taken by NASA’s Magellan mission in the 1990s, and filled the lowlands with water, leaving the highlands exposed as Venusian continents. The study also factored in an ancient sun that was up to 30 percent dimmer. Even so, ancient Venus still received about 40 percent more sunlight than Earth does today.

 

“In the GISS model’s simulation, Venus’ slow spin exposes its dayside to the sun for almost two months at a time,” co-author and fellow GISS scientist Anthony Del Genio said. “This warms the surface and produces rain that creates a thick layer of clouds, which acts like an umbrella to shield the surface from much of the solar heating. The result is mean climate temperatures that are actually a few degrees cooler than Earth’s today.”

 

The research was done as part of NASA’s Planetary Science Astrobiology program through the Nexus for Exoplanet System Science (NExSS) program, which seeks to accelerate the search for life on planets orbiting other stars, or exoplanets, by combining insights from the fields of astrophysics, planetary science, heliophysics, and Earth science. The findings have direct implications for future NASA missions, such as the Transiting Exoplanet Survey Satellite and James Webb Space Telescope, which will try to detect possible habitable planets and characterize their atmospheres.

Quelle: NASA

 

 


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