Satélite de espionagem poderá caír nos próximos dias

Segundo as informações disponíveis, este satélite está fora de controlo, e poderá caír em qualquer lugar da Terra. Previsões mais exactas, neste tipo de ocorrências, só são possíveis nas últimas órbitas, por isso o pré-aviso é sempre curto.

Fonte: LA Times

Link: MSNBC


U.S. warns satellite will fall to Earth soon
Officials monitoring the spy apparatus say it is losing orbit. Exactly when and where it will crash isn't yet known.

By Richard A. Serrano, Los Angeles Times Staff Writer

January 27, 2008

WASHINGTON -- Senior government officials said Saturday that they were closely watching a failing U.S. spy satellite that had begun the process of "de-orbiting" and cautioned that the large device was no longer controllable and could hit the Earth as early as late February.

"Appropriate government agencies are monitoring the situation," said Gordon Johndroe, a spokesman for the National Security Council. "Numerous satellites over the years have come out of orbit and fallen harmlessly. We are looking at potential options to mitigate any possible damage this satellite may cause."

U.S. officials are unable to maneuver the satellite, and Johndroe declined to say whether it would be possible to shoot down the spy apparatus before it plummets to Earth. He would not divulge further specifics.

At the Pentagon, Air Force Lt. Col. Karen Finn confirmed that Defense officials thought the satellite could hit the Earth soon but that more analysis would be needed to better determine when, where and in what condition the satellite might crash.

"We are monitoring it," she said. "The NSC has been talking to us about this, and they confirm it is a de-orbiting satellite."

White House officials had little more to say about the situation beyond what the Pentagon and the National Security Council disclosed.

The Associated Press, citing unnamed sources, hinted that the satellite could contain hazardous materials, but the sources were not certain.

Nevertheless, administration officials took the precaution of notifying U.S. lawmakers and other nations, and pledged to keep them aware of the situation as the satellite's failure nears.

Many commercial satellites contain small rockets that ground controllers use to adjust their orbits, and solar panels and rechargeable batteries for power.

Batteries in solar power systems usually are considered hazardous for disposal purposes.

Satellites launched toward planets farther from the sun more often rely on nuclear power.

Some early U.S. and Russian satellites orbiting Earth also used nuclear power, and several accidents over the years resulted in releases of radioactive material.

The contents and operation of U.S. military and spy satellites are classified.

The most significant uncontrolled re-entry by a U.S. craft was Skylab in 1979. Debris from the 78-ton abandoned space station fell into the Indian Ocean and over remote areas of Australia.

In 2000, NASA engineers used rockets aboard the 17-ton Compton Gamma Ray Observatory to bring the satellite down in the Pacific Ocean. And in 2002, officials think debris from a 7,000-pound science satellite fell into the Persian Gulf.

richard.serrano@latimes.com

Luzes sobre a Antártida

A Via Láctea sobre o observatório

Um eclipse da Lua em 40 segundos

A Spaceship 2, de Burt Rutan

Foi finalmente apresentada a sucessora da Spaceship One, de Burt Rutan, que foi a primeira nave privada a ultrapassar a barreira dos 100 Kms de altitude, em 2004, vencendo o X-Prize. Esta nova versão será capaz de transportar mais passageiros.

Juntamente com a Spaceship Two, será também construído um novo avião de lançamento, o White Knight 2, que terá a particularidade de ter dois cockpits - clique nas imagens abaixo para aumentar.






Fonte: MSNBC

Link:

• Virgin Galactic
• Gizmodo (mais imagens)
• BBC
• National Geographic
  

FIRST LOOK AT SPACESHIPTWO

The new designs for Virgin Galactic's SpaceShipTwo rocket plane and WhiteKnightTwo mothership were unveiled in New York today, and they include some unexpected twists. In fact, you could be excused if you think you're seeing double, or even triple.

Today's event was the most detailed look yet at the craft that will carry on the legacy of SpaceShipOne, the first commercially developed spaceship and winner of the $10 million Ansari X Prize in 2004.

The biggest twist is that the WhiteKnightTwo plane has spread out and sprouted another passenger cabin on its 140-foot-long wing. The two cabins and four Pratt & Whitney jet engines straddle a central mount for the rocket plane, which will be carried to an altitude of 50,000 feet and dropped. Then SpaceShipTwo will light up its hybrid rocket engine for the final push to the edge of outer space, reaching an altitude of at least 68 miles (110 kilometers).

The twin cabins are basically carbon copies of the SpaceShipTwo cabin, so riding on WhiteKnightTwo will give passengers a taste of what the big blast to space will be like. While commercial astronauts are taking their trip to see the curving earth below the black sky of space, the passengers on WhiteKnightTwo will experience a lower-altitude version of the experience - including a bit of zero-G.

Burt Rutan, the craft's designer and head of California-based Scaled Composites, imagined a scenario in which a husband riding in the mothership watches his wife take off in the spaceship, sitting only 25 feet away.

"You'll say, 'Honey, have a nice flight,'" Rutan told scores of journalists and dignitaries at the American Museum of Natural History. "While she is enjoying black sky and weightlessness, you, in the launch airplane, will be doing parabolas and floating about the cabin."

Stan Honda / AFP - Getty Images Richard Branson, the billionaire founder of the Virgin Group, and Scaled Composites aerospace designer Burt Rutan unveil scale models of the WhiteKnightTwo carrier aircraft, at left, and the SpaceShipTwo rocket plane amid hoopla at the American Museum of Natural History.

SpaceShipTwo is designed to carry six passengers and two pilots into space, with enough headroom to allow for free floating. It's about twice as large as SpaceShipOne, with 18-inch-wide windows and reclining seats for fare-paying fliers.

More than 100 people are already in line for spaceflights, at a cost of $200,000 per person, and Rutan expects there to be thousands more: He said the innovations incorporated into SpaceShipTwo will make human spaceflight "at least as safe as the airliners of the late '20s."

One of the reporters was surprised at that: Shouldn't spaceflight ideally be as safe as commercial aviation is today?

"Don't believe anyone who tells you that the entry level of new spaceships will be as safe as the modern airliner," Rutan responded. He noted that the fatality rate for orbital spaceflight has been 4 percent, and that he was aiming for the suborbital SpaceShipTwo to be "hundreds of times safer."

When will it fly?
Virgin Galactic said work on SpaceShipTwo was nearly 60 percent complete, and WhiteKnightTwo was more than 80 percent complete.

In the past, Virgin Galactic has said passenger flights could start in the 2009-2010 time frame - but that was before last July's fatal accident at Scaled Composites' Mojave testing ground. The development of SpaceShipTwo's rocket engine has been held up because of the accident investigation, and today Virgin Galactic is saying only that WhiteKnightTwo will go into flight tests later this year. Gliding drop tests of the SpaceShipTwo craft, sans engine, could begin this year as well, said Stephen Attenborough, Virgin Galactic's commercial director.

"This is very unlikely to be a program that will be delivered on a straight line," Attenborough told me.

Several would-be passengers attended today's event, and were easily recognizable because of their black Virgin-branded flight suits. Perveen Crawford, Virgin Galactic's first paid-up customer from Hong Kong, told me that she was ready to go anytime.

"It doesn't matter how it looks, just take me up there," she said.

Virgin Galactic's founder, British billionaire Richard Branson, has said he'll give his 89-year-old father, Edward, a ride on SpaceShipTwo as a sign of his confidence in its safety. "They'll have to do it fairly quickly, or I won't be around," Edward Branson told me jokingly after the news conference.

Edward Branson hasn't yet gone through astronaut training, but 80 other fliers-to-be have taken practice sessions at the NASTAR Center in Pennsylvania. Passengers are expected to endure accelerations of up to 3.5 times Earth's gravity, or 3.5 G's, on the way up - and up to 6 G's coming down. NASTAR's centrifuge duplicates that flight profile for training purposes.

Stan Honda / AFP - Getty Images British billionaire Richard Branson and aerospace designer Burt Rutan hold up a scale model of the SpaceShipTwo rocket plane hitched aboard its WhiteKnightTwo carrier aircraft after today's news briefing.

In the wake of the centrifuge sessions, Attenborough said two fliers have withdrawn from the flight program because of health concerns, and three have delayed their training - which translates into a higher-than-expected 93 percent success rate.

People wouldn't necessarily be the only payload: Virgin Galactic President Will Whitehorn said the WhiteKnightTwo air-launch system could also be adapted for putting satellites into orbit. Even on the passenger flights, scientific experiments could ride along just as they do on government-supported spaceflights, "helping to answer key questions about climate and the mysteries of the universe," Richard Branson said.

Making their mark
Compared with the pointy-nosed look of SpaceShipOne, the cabin designs for SpaceShipTwo and WhiteKnightTwo look a bit more rounded, more like a business jet than a Looney Tunes rocketship. The white-and-red colors of the first commercial spaceship were replaced on the scale models shown today with a white, blue and black motif.

The twin tails and the belly of the SpaceShipTwo craft were emblazoned with a design based on the iris of Richard Branson's eye.

Branson had history on his mind as he addressed today's audience.

"2008 really will be the year of the spaceship," he said. Later on, Branson was asked whether he hoped he'd go down in history for backing the first commercial spaceline. Branson quickly gave the credit to Rutan, but then noted that everyone would like to leave their mark on earth.

"I suppose we'd all like to make our mark when we're out of Earth, too," Branson said.

You can get your own look at the new design concepts at Virgin Galactic. And stay tuned for further updates later today, here on the Log.

Update for 5 p.m. ET: Some of the folks posting comments have noted that Branson has positioned himself as a champion of climate consciousness as well as commercial spaceflight. During comments at this morning's news conference as well as at an afternoon session, Branson tried to address that pairing.

He noted that environmentalist James Lovelock was among the first to sign up for a seat on SpaceShipTwo. "He's told me that he thinks this project is one of the most important industrial projects of the 21st century," Branson said.

Branson also downplayed aviation's contribution to greenhouse-gas production. He argued that "seemingly benign" factors such as information technology were actually bigger contributors to the carbon dioxide problem - and that space technologies could make a big contribution to analyzing and even solving environmental ills.

This afternoon's audience was aimed primarily at space boosters rather than journalists, and there was somewhat more whooping and hollering as Branson and Rutan gave their spiel. That brought a smile to Rutan's lips.

"This is a better crowd ... I've always said that my best talks are when there's absolutely no press at all," Rutan joked.

Foto espetacular - a Terra, de noite

Nesta imagem vemos um crescente, na parte inferior da foto, onde a Terra ainda é iluminada pelo Sol, e onde se podem ver detalhes da superfície. Não podem ser vistas as luzes das cidades porque são demasiado fracas em relação ao brilho deste crescente.

Clique para aumentar.

A NASA arrisca-se a estar a criar o maior vibrador do Mundo!

Surgem os primeiros problemas com o foguetão Ares I, que deverá ser o foguetão que substituirá o Space Shuttle como meio de lançamento para naves tripuladas dos Estados Unidos. Estes problemas prendem-se com vibrações perigosas de toda a estrutura, que serão agora estudadas pela NASA durante os próximos anos. Creio ser um problema grave e de difícil solução, uma vez que nunca foram usados foguetões de combustível sólido para lançar astronautas no espaço. É uma área onde não há experiência, e assim o potencial de risco e de ocorrência de desastres é maior, contrariando o objectivo da NASA de criar um meio de lançamento mais seguro do que o Space Shuttle.

Links:

• Environmental Grafitti
• Washington Post
• Chron.com
• NASAWatch

NASA Moon Rocket May Shake Too Much

By SETH BORENSTEIN
The Associated Press
Saturday, January 19, 2008; 1:25 AM

WASHINGTON -- NASA is wrestling with a potentially dangerous problem in a spacecraft, this time in a moon rocket that hasn't even been built yet.

Engineers are concerned that the new rocket meant to replace the space shuttle and send astronauts on their way to the moon could shake violently during the first few minutes of flight, possibly destroying the entire vehicle.

"They know it's a real problem," said Carnegie Mellon University engineering professor Paul Fischbeck, who has consulted on risk issues with NASA in the past. "This thing is going to shake apart the whole structure, and they've got to solve it."

If not corrected, the shaking would arise from the powerful first stage of the Ares I rocket, which will lift the Orion crew capsule into orbit.

NASA officials hope to have a plan for fixing the design as early as March, and they do not expect it to delay the goal of returning astronauts to the moon by 2020.

"I hope no one was so ill-informed as to believe that we would be able to develop a system to replace the shuttle without facing any challenges in doing so," NASA administrator Michael Griffin said in a statement to The Associated Press. "NASA has an excellent track record of resolving technical challenges. We're confident we'll solve this one as well."

Professor Jorge Arenas of the Institute of Acoustics in Valdivia, Chile, acknowledged that the problem was serious but said: "NASA has developed one of the safest and risk-controlled space programs in engineering history."

The space agency has been working on a plan to return to the moon, at a cost of more than $100 billion, since 2005. It involves two different rockets: Ares I, which would carry the astronauts into space, and an unmanned heavy-lift cargo ship, Ares V.

The concern isn't the shaking on the first stage, but how it affects everything that sits on top: the Orion crew capsule, instrument unit, and a booster.

That first stage is composed of five segments derived from the solid rocket boosters that NASA uses to launch the shuttle and would be built by ATK Launch Systems of Brigham City, Utah.

The shaking problem, which is common to solid rocket boosters, involves pulses of added acceleration caused by gas vortices in the rocket similar to the wake that develops behind a fast-moving boat, said Arenas, who has researched vibration and space-launch issues.

Those vortices happen to match the natural vibrating frequencies of the motor's combustion chamber, and the combination causes the shaking.

Senior managers were told of the findings last fall, but NASA did not talk about them publicly until the AP filed a Freedom of Information Act request earlier this month and the watchdog Web site Nasawatch.com submitted detailed engineering-oriented questions.

The response to those questions, given to both Nasawatch and AP, were shared with outside experts, who judged it a serious problem.

NASA engineers characterized the shaking as being in what the agency considers the "red zone" of risk, ranking a five on a 1-to-5 scale of severity.

"It's highly likely to happen and if it does, it's a disaster," said Fischbeck, an expert in engineering risks.

The first launch of astronauts aboard Ares I and Orion is set for March 2015.

Do site NASAWatch

NASA's Exploration Systems Mission Directorate Responds to Ares 1 and Orion Questions

Keith Cowing
Thursday, January 17, 2008

Editor's note: Earlier this month I submitted a series of questions to NASA's Exploration Systems Mission Directorate (ESMD) regarding the Ares 1 and Orion projects. The following was provided to me by ESMD PAO today:
Questions from Keith Cowing, NASA Watch

Q: Do launch vibroacoustics, oscillations, etc. generated by the current Ares I design exceed acceptable baselined limits for the Orion spacecraft? Do these oscillations exceed limits and/or pose a risk to the crew inside the Orion spacecraft? If so, to what extent to they exceed acceptable limits?

Q: Using a standard NASA 5x5 risk management matrix, what is the current risk rating of Ares I vibroacoustics and oscillations issue by the Constellation and Ares programs?

Q: Have any presentations given by ATK, NASA or other contractor personnel in November or December 2007 - or at any other time - characterized the risk (using a standard NASA 5x5 risk management matrix) to Ares I first stage development as being 4x5 due to incomplete requirements and/or insufficient performance from the DAC-1 Ares I Design?

Q: Are studies underway at NASA to reduce the weight of Orion and associated hardware so as to allow additional weight to be added to the Ares I to alleviate oscillation issues and/or conform to lower performance (payload capacity) by the Ares I?

Q: Is NASA looking at stiffening the Ares I structure so as to pass vibrations on to the Ares I upperstage and payloads i.e. Orion? If so what loads will be transferred to upper stages and/or payloads (Orion)?

Q: Is NASA looking to use a dampening system to handle these vibroacoustic or oscillation loads? If so, what is the weight of such this system? How much would the weight of such a system affect Ares I payload capacity? What would be the added cost of such a dampening system?

Q: Is a tiger team or working group working to report back to Ares and/ or Constellation program managers on these Ares I vibration and oscillation issues? Is this tiger team due to report its findings in March 2008? If not March 2008, when are these results due to be reported and to whom will these results be reported?

Q: Is any portion of the current tiger team's deliberations or proposed solutions considered to be restricted information due to ITAR concerns?

Q: Was NASA Administrator Griffin made aware of these Ares I vibration issues in 2007? If so, when was he made aware of these issues? Who told him about these issues? What specifically was Griffin told about these issues? What was Griffin's response to these issues?

Q: Is NASA currently working on any plans for alternate ways to launch the Orion spacecraft? Do these alternate approaches involve the use of EELVs? Do they involve other commercially available launch vehicles? Do they involve use of shuttle-derived launch systems? Do they involve the use of any launch vehicle design or concept with the working name of "Jupiter" or "Direct"?

Q: If Administrator Griffin was ware of these design issues in 2007 did he inform Congress of these issues? If so, when? Has information on these design issues been presented to members of Congress or to Congressional staff by anyone at NASA?

Q: Has any information on these Ares I design issues been presented to the Government Accountability Office? If so, when?

NASA's Exploration Systems Mission Directorate responds:

Thrust oscillation, also called resonant burning, is a phenomenon characterized by increased acceleration pulses that may be felt during the latter stages of first-stage powered flight. Depending on the amplitude of these pulses, the impact on the vehicle structure and astronauts may be significant.

Thrust oscillation is a characteristic of all solid rocket motors including the first stage of the Ares I launch vehicle. Vortices, created inside the solid rocket motor by the burning propellant or other flow disturbances, can coincide, or tune, with the acoustic modes of the motor combustion chamber, generating longitudinal forces. These longitudinal forces may increase the loads experienced by the Ares I during flight, and may exceed allowable loads on various portions of the vehicle and allowable forces on the astronaut crew.

During any new development program, program risks must be identified and resolved prior to hardware development. Thrust oscillation is such a risk. It is being reviewed, and a mitigation plan is being developed. NASA is committed to resolve this issue prior to the Ares I Project's preliminary design review, currently scheduled for late 2008.

By March 2008, the space agency anticipates having:

* Characterized the potential impact of thrust oscillation (sensitivities to the crew and vehicle components)
* Assessed design feasibilities
* Formulated a plan to manage sensitive design parameters (tests, trade studies and analyses required)

NASA has given careful consideration to many different launch concepts (shuttle-derived, evolved expendable launch vehicle, etc.) over several years. This activity culminated with release of the Exploration Systems Architecture Study in 2005. Since then, the baseline architecture has been improved to decrease life cycle costs significantly.

NASA's analysis backs up the fact that the Ares family enables the safest, least expensive launch architecture to meet requirements for missions to the International Space Station, the moon and Mars. NASA is not contemplating alternatives to the current approach.

NASA is studying the phenomenon of resonant burning of the Ares I first stage in order to improve prediction of the phenomenon and its associated impacts. Thrust oscillation forces may be reduced by vehicle structures, as is the case with the space shuttle and Titan IV.

NASA is working to understand how thrust oscillation may impact the entire stack - Ares first stage, upper stage, and Orion crew vehicle -- and to determine how to minimize the impact. NASA is assessing all vehicle system impacts and defining potential solutions. This includes reviewing thrust oscillation impacts on the Orion, upper stage, J-2X engine, reaction control system, first stage, and avionics. Such a thorough approach -- working with all systems to identify all scenarios and their corresponding sensitivities -- is crucial for successful mitigation.

The Constellation Program has brought in experts from NASA and industry to review these issues and lessons already learned from similar induced responses - namely, affects on launch vehicle hardware and allowable amplitudes of thrust oscillation. The Orion and Ares teams are holding detailed discussions and developing a plan to fully characterize Ares I thrust oscillation, assess any design changes that may be proposed, and manage sensitive design parameters with additional tests, trade studies and analyses.

An integrated thrust oscillation focus team is reviewing the various components of the Ares I and Orion integrated vehicle and the potential impacts of thrust oscillation on the motor, loads and controls, first stage, upper stage, and Orion.

All "at risk" items are being defined (including structural, performance, and human risk items), and a resolution matrix is being established. The goal is to have risks defined and quantified and a mitigation path determined by March 2008.

After the Ares I system design review in late October 2007, thrust oscillation was identified as a risk by the Ares Project and assigned a risk of four-by-five (out of five-by-five) on the NASA risk matrix. NASA uses the risk matrix as a way to track the probability that a risk may manifest itself and the overall impact if the risk does manifest itself. Risks are scored from 1 (low) to 5 (high) for both probability and overall impact.

The thrust oscillation risk is not directly associated with launch vehicle performance or first-stage development. The thrust oscillation risk is associated with the integrated stack, meaning the assembled Ares I first stage, upper stage and Orion crew vehicle. Ares I performance is tracked on a monthly basis, and Ares I consistently has met its performance requirements with margin.

The administrator makes it a practice to be fully informed on all matters concerning shuttle operations and Ares and Orion development. Details on the thrust oscillation issue were communicated to senior agency management first in October 2007 at the Exploration Systems Mission Directorate quarterly program review and again in mid-November 2007 at the Constellation integrated stack status meeting, which the NASA administrator attended.

At the November meeting, the Ares I thrust oscillation issue was addressed as a very small portion of a much broader briefing to the NASA administrator. Steve Cook, manager of the Ares Projects Office at NASA's Marshall Space Flight Center, led the discussion. In response, the administrator stated that he understood the challenge and that he was aware that a team had been working on the issue since early November.

Because it is early in the process, NASA is still working to characterize the potential impact, assess design feasibilities and formulate a plan to address the technical analysis on the thrust oscillation issue. Therefore, NASA has not held a formal briefing for congressional staff or Government Accountability Office staff but has been open about this issue since first learning about it.

Thrust oscillation is a new engineering challenge to the developers of Ares - but a challenge very similar to many NASA encountered during the Apollo Program and development of the space shuttle. Every time NASA faces an engineering challenge - and it faces many - agency engineers examine all the options for addressing the issue. NASA has an excellent track record of resolving technical challenges. NASA is confident it will solve this one as well.

Novas imagens de alta resolução da superfície de Mercúrio

À medida que vão sendo processadas as imagens da primeira aproximação da MESSENGER a Mercúrio, vão sendo divulgadas novas imagens de alta definição da superfície. São de esperar mais imagens nos próximos dias.

Clique nas imagens para aumentar.

Fonte: MESSENGER

As MESSENGER approached Mercury on January 14, 2008, the spacecraft’s Narrow-Angle Camera on the Mercury Dual Imaging System (MDIS) instrument captured this view of the planet’s rugged, cratered landscape illuminated obliquely by the Sun. The large, shadow-filled, double ringed crater to the upper right was glimpsed by Mariner 10 more than three decades ago and named Vivaldi, after the Italian composer. Its outer ring has a diameter of about 200 kilometers (about 125 miles). MESSENGER’s modern camera has revealed detail that was not well seen by Mariner 10, including the broad ancient depression overlapped by the lower-left part of the Vivaldi crater. The MESSENGER science team is in the process of evaluating later images snapped from even closer range showing features on the side of Mercury never seen by Mariner 10. It is already clear that MESSENGER’s superior camera will tell us much that could not be resolved even on the side of Mercury viewed by Mariner’s vidicon camera in the mid-1970s.

This MESSENGER image was taken from a distance of about18,000 kilometers (11,000 miles), about 56 minutes before the spacecraft's closest encounter with Mercury. It shows a region roughly 500 kilometers (300 miles) across, and craters as small as 1 kilometer (0.6 mile) can be seen in this image.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


Just 21 minutes after MESSENGER’s closest approach to Mercury, the Narrow Angle Camera (NAC) took this picture showing a variety of intriguing surface features, including craters as small as about 300 meters (about 300 yards) across. This is one of a set of 68 NAC images showing landscapes near Mercury’s equator on the side of the planet never before imaged by spacecraft. From such highly detailed close-ups, planetary geologists can study the processes that have shaped Mercury’s surface over the past 4 billion years. One of the highest and longest scarps (cliffs) yet seen on Mercury curves from the top center down across the right side of this image. (The Sun is shining low from the left, so the scarp casts a wide shadow.) Great forces in Mercury’s crust have thrust the terrain occupying the left two-thirds of the picture up and over the terrain to the right. An impact crater has subsequently destroyed a small part of the scarp near the top of the image.

This image was taken from a distance of only 5,800 kilometers (3,600 miles) from surface of the planet and shows a region about 170 kilometers (about 100 miles) across.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

During its flyby of Mercury, the MESSENGER spacecraft acquired high-resolution images of the planet's surface. This image, taken by the Narrow Angle Camera (NAC) on the Mercury Dual Imaging System (MDIS), was obtained on January 14, 2008, about 37 minutes after MESSENGER's closest approach to the planet. The image reveals the surface of Mercury at a resolution of about 360 meters/pixel (about 1180 feet/pixel), and the width of the image is about 370 kilometers (about 230 miles). This image is the 98th in a set of 99 images that were taken in a pattern of 9 rows and 11 columns to enable the creation of a large, high-resolution mosaic of the northeast quarter of the region not seen by Mariner 10. During the encounter with Mercury, the MDIS instrument acquired image sets for seven large mosaics with the NAC.

This image shows a previously unseen crater with distinctive bright rays of ejected material extending radially outward from the crater's center. A chain of craters nearby is also visible. Studying impact craters provides insight into the history and composition of Mercury as well as dynamical processes that occurred throughout our Solar System. The MESSENGER Science Team has begun analyzing these high-resolution images to unravel these fundamental questions.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

A imagem do dia!

Acabei de descobrir isto num site de t-shirts. Lembrei-me daquelas pessoas que diziam que acharam obsceno o espetáculo dos astronautas a colocarem a bandeira americana na Lua... Bom, o facto é que quem lá foi... foram eles :)

MESSENGER mostra pela primeira vez a face desconhecida de Mercúrio

Clique para aumentar.

Quando a sonda Mariner 10 passou por Mercúrio, em 1974 e 1975, fotografou sempre a mesma metade do planeta. Agora, 33 anos depois a MESSENGER fotografou cerca de metade da face de Mercúrio que não foi observada então.

A MESSENGER ainda passará duas vezes por Mercúrio, antes de finalmente entrar em órbita do planeta, em Março de 2011.


Fonte: MESSENGER

MESSENGER’s First Look at Mercury’s Previously Unseen Side

When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter. As a consequence, Mariner 10 was able to image less than half the planet. Planetary scientists have wondered for more than 30 years about what spacecraft images might reveal about the hemisphere of Mercury that Mariner 10 never viewed.

On January 14, 2008, the MESSENGER spacecraft observed about half of the hemisphere missed by Mariner 10. This image was snapped by the Wide Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, about 80 minutes after MESSENGER's closest approach to Mercury (2:04 pm EST), when the spacecraft was at a distance of about 27,000 kilometers (about 17,000 miles). The image shows features as small as 10 kilometers (6 miles) in size. This image was taken through a filter sensitive to light near the red end of the visible spectrum (750 nm), one of a sequence of images taken through each of MDIS’s 11 filters.

Like the previously mapped portion of Mercury, this hemisphere appears heavily cratered. It also reveals some unique and distinctive features. On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and perhaps one of the youngest, basins in the Solar System. The new image shows the complete basin interior and reveals that it is brighter than the surrounding regions and may therefore have a different composition. Darker smooth plains completely surround Caloris, and many unusual dark-rimmed craters are observed inside the basin. Several other multi-ringed basins are seen in this image for the first time. Prominent fault scarps (large ridges) lace the newly viewed region.

Other images obtained during the flyby will reveal surface features in color and in much more detail. Collectively, these images and measurements made by other MESSENGER instruments will soon provide a detailed global view of the surface of Mercury, yielding key information for understanding the formation and geologic history of the innermost planet.