Tag Archives: Mercury

Discovery of carbon on Mercury reveals the planet’s dark past

The Conversation

Ivy Shih, The Conversation

Mercury has been found to have a dark side with graphite, a crystalline form of carbon commonly found in pencils, being the source of the mysterious dark colouration of the planet’s surface.

The study, published this week in Nature Geoscience, was led by a team from the Johns Hopkins University Applied Physics Laboratory in the US, which analysed measurements collected by NASA’s Messenger spacecraft as it went through its final orbits of Mercury.

The findings not only test theories of early planetary formation but may offer an explanation of the amount of carbon here on Earth.

Remains of a primordial crust

The surface colour of planetary bodies is often an indicator of the elements that make them up. For example, the distinctive rusty red appearance of Mars can be attributed to iron oxide.

It had previously been believed that the iron and titanium were typically responsible for the dark coloration on planetary surfaces. However, Mercury is quite dark, but lacked high enough concentrations of those elements to account for its colour.

“Mercury’s surface was significantly darker than we could account for on the basis of our understanding of Mercury’s surface chemistry,” said Dr Patrick Peplowski, from the Johns Hopkins University Applied Physics Laboratory, and lead author on the study.

“So what was causing Mercury to be so dark?”

By carefully examining data sent back to Earth by the Messenger probe, the team found that the dark colouration was due to the presence of carbon, with Mercury having high levels than any other planets or their moons.

The discovery of carbon on Mercury was an unexpected one, so much so that none of the instruments on Messenger were designed to detect the element. Instead, Peplowski and his colleagues had to use multiple instruments to identify the carbon.

Need for continued planetary exploration

The discovery gives weight to a theory on how Mercury was formed. The carbon-rich material was detected underneath younger volcanic materials that make up Mercury’s present day surface. This suggests that early Mercury’s original carbon-rich crust may have been formed from graphite that floated to the top of a global magma ocean.

These primordial “floating crusts” provide a rare perspective on early planetary formation.

“This is interesting because the original crusts of the other planets were destroyed long ago by processes like volcanic resurfacing, plate tectonics and erosion,” Peplowski told The Conversation.

“The carbon we see today may be the remains of that ancient, 4.5 billion-year-old crust.”

However, there are still questions as to how the planetary crust was originally formed and why carbon was found around some craters and not others.

“There is a lot of follow-on work to be done,” said Peplowski. “Future missions to Mercury might benefit from instrumentation specifically designed to map carbon in order to follow up on this result.”

The next planetary exploration of Mercury could provide further answers, with the European Space Agency launching the BepiColumbo probe to Mercury next year.

“It has an entirely new suite of instruments that can add to our understanding of carbon on Mercury.”

Planetary puzzles

Dr Helen Maynard-Casely, an Instrument Scientist from the Australian Nuclear Science and Technology Organisation, who was not involved in the study, said the study sheds light on some longstanding mysteries in planetary science.

She added that the theory they study suggests that how Mercury evolved shares many similarities to the early formation of the Moon.

“The early crust of the Moon was made of lighter minerals. It is thought these were stripped off the Earth. In terms of planetary formation, these minerals are like froth on a coffee. Then, as the surface of the Moon has evolved, impacts and lava flows have brought the darker material onto the faces of the Moon,” she said.

“What they’re seeing is that this darker material on Mercury is the remnants of the early frothy material. Graphite is light compared to the other materials on Mercury. They suggest this rose to the top at the very beginning of the planet’s formation creating the first crust of Mercury as it was cooling down.”

But throughout the life of Mercury in the solar system, repeated impacts had churned up the crust, leaving very little of the early surface intact.

Maynard-Casely says that the discovery came as a surprise and may change our view on the how the solar system was formed, and the current model of predicting the presence of carbon, including here on Earth.

“Carbon’s been a very tricky element to pin down, even on Earth, and it is a puzzle to discover what has happened to our carbon. There’s a thought now that a lot of the carbon on Earth is trapped further down within the interior and that we are missing a lot of minerals. There is currently a bit of a worldwide hunt for these,” she said.

“The knowledge of carbon’s significance on Mercury would bring those questions back to the forefront and reinvigorate discussions.”

The ConversationIvy Shih, Editor, The Conversation

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

 

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Dumb or dumber? Jim Carrey’s anti-vax antics expose the tactics of internet cranks

The Conversation

Michael J. I. Brown, Monash University and Geraint Lewis, University of Sydney

Comedian Jim Carrey flew his anti-vaccination colours on Twitter last week, railing against new Californian laws designed to reduce the number of unvaccinated children in public schools.

“California Gov says yes to poisoning more children with mercury and aluminum in mandatory vaccines. This corporate fascist must be stopped.”

Along the way, Carrey has provided some excellent examples of the tactics used by online cranks, such as emotional escalation, errors of omission, dismissing experts and proclaiming to support science while simultaneously undermining it.

It is by teasing out these crank tactics that we can see Carrey’s tweets for what they are: well-intentioned but misguided attacks against a lifesaving practice that has been proven time and again to be safe and effective according to our very best scientific practices.

Emotional escalation

Carrey’s tweets are notable for his use of CAPSLOCK, the typed equivalent of shouting.

“A trillion dollars buys a lot of expert opinions. Will it buy you? TOXIN FREE VACCINES, A REASONABLE REQUEST!

Emotional escalation, including yelling and insults, tend to polarise debates. Uncivil comments can also adversely impact how people interpret facts they have previously read.

Carrey’s anti-vaccination tweets also included photos of autistic boys, further escalating emotions. We feel sympathy for the boys and their families, but this is a poor substitute for statistical studies, which haven’t found any connection between vaccines and autism.

Carrey’s use of photos of autistic boys may also have backfired. One photo showed Alex Echols, who suffers from Tuberous Sclerosis, a genetic disorder often leads to autism. Echols’ autism has nothing to do with vaccines, yet he was initially used to emotionally bolster Carrey’s arguments (Carrey has since apologised).

Mercury matters

Ideas touted by cranks are often superficially true, yet misleading. A splendid example is:

“They say mercury in fish is dangerous but forcing all of our children to be injected with mercury in thimerosol is no risk. Make sense?”

This contains an error of omission, as it actually refers to two different mercury containing compounds. Methylmercury accumulates in animals and is dangerous when ingested. Thimerosal was once a common preservative in vaccines, and breaks down into ethylmercury, which is rapidly removed from the body.

Does Carrey’s tweet “make sense?” No.

I’m pro-science

Historian of science Michael Gordin succinctly notes:

“No one in the history of the world has ever self-identified as a pseudoscientist. There is no person who wakes up in the morning and thinks to himself, ‘I’ll just head into my pseudolaboratory and perform some pseudoexperiments to try to confirm my pseudotheories with pseudofacts.'”

Cranks often proclaim their love of science while simultaneously attacking it. Carrey tweeted:

“I repeat! I AM PRO-VACCINE/ANTI-NEUROTOXIN, as is Robert Kennedy Jr. Please read the following article and book http://bit.ly/1GLSpHf

Carrey claims to be pro-vaccine while credulously repeating dangerous myths about their risks. He lacks expertise to evaluate studies of the efficacy and risks of vaccines (which often use similar scientific techniques), but has reached strong yet contrary opinions on these topics. How can this be reasonable?

The tactic of proclaiming support for science while simultaneously undermining it isn’t restricted to comedians. The Australian newspaper has claimed it “supports global action on climate change based on the science,” but often repeats stories sourced from the internet that reject peer-reviewed climate science.

Dismissing experts

So how does Carrey dismiss the work of thousands of medical researchers from around the globe? Very easily. Like many internet cranks, he makes unfounded accusations of scientific organisations being corrupt:

“The CDC can’t solve a problem they helped start. It’s too risky to admit they have been wrong about mercury/thimerasol. They are corrupt.”

This is a very common tactic for dismissing broad swathes of evidence. Some climate contrarians believe scientists are engaged in criminal activity.

Such claims get into conspiracy theory territory, particularly as independent groups of scientists scattered across the globe get comparable results. For example, the American Berkeley Earth team – which started off sympathetic to climate change sceptics – finds very similar temperature rise across Australia as Bureau of Meteorology scientists.

Even sympathetic media generally tone down bloggers’ claims of criminal activity. That said, it is curious that innocent activities such as data processing and analysis are sometimes referred to as (more ominous sounding) data manipulation.

A less severe variant of the corruption tactic is claiming experts have a conflict of interest, as they are paid to undertake their work. Of course, this allows one to dismiss evidence from almost any professional – be that a doctor, lawyer, psychologist or scientist – leaving only courageous internet amateurs.

Popularity

Why is anyone paying attention to Carrey when it comes to vaccines? The answer is celebrity. He is a successful actor, with almost 15 million followers on Twitter. If he says something controversial, millions of people immediately know about it.

Crank ideas, which have been rejected by the scientific community, only remain alive while they have support from the public, celebrities, millionaires or politicians. Without popularity, crank ideas wither and die.

Cranks and their supporters know they must remain popular to survive, and game the system. Cranks often badge themselves as “coalitions”, “institutes”, “networks” and “alliances.” Cranks can buy social media followers or use “follow back” accounts to give the appearance of significant support. Websites often contain myriad links to fellow cranks, which may be an attempt to game search engine rankings. So cranks may appear more significant to the public and media than they truly are.

Of course, to have celebrity support is incredibly helpful to cranks. Along with Carrey, Bill Maher, Robert F Kennedy Jr. and Jenny McCarthy have promoted the anti-vaccination cause. They have helped keep this cause alive, even though it’s at odds with medical research.

Carrey almost certainly means well. But, like many internet cranks, he doesn’t have the expertise to distinguish scientific fact from dangerous myth. The recent death of a woman from measles and the Disneyland measles outbreak highlight just how dangerous such myths can be.


Michael J. I. Brown is Associate professor at Monash UniversityGeraint Lewis is Professor of Astrophysics at University of Sydney.

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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From Mercury to Pluto: the year ahead in planetary exploration

The Conversation

By Donna Burton, University of Southern Queensland

2015 is already shaping up to be a big year in astronomy and planetary exploration, with the best yet to come. Here are some highlights to keep your eye on throughout the year.

Opportunity

January 25 marked 11 years since the Opportunity Rover landed on Mars in 2004 just three weeks after its now inactive twin Spirit. This view is taken from the rim of the Endeavour Crater at a point known as Cape Tribulation.

Opportunity ’s view from Cape Tribulation on the rim of Endeavour Crater, January 22, 2015
NASA/JPL-Caltech/Cornell Univ./Arizona State Univ

This is the highest point that the rover Opportunity has reached since it left the Victoria Crater area back in 2008. It has taken three years for the 180kg solar powered robot to complete the journey down to the Endeavour Crater, which measures 22 kilometres in diameter.

One of its key mission accomplishments has been the characterisation of soft rocks and soil to provide evidence of past water on the Mars. Asteroid 39392 Opportunity was named after this hardworking rover.

Dawn probe

This animation of the dwarf planet Ceres was made by combining images taken by NASA’s Dawn spacecraft on January 25, 2015.
NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Later this year in March, the NASA probe Dawn will arrive at the dwarf planet Ceres. Ceres is one of the largest known bodies in the asteroid belt. It is thought that favourable conditions for life may have once existed there, and the presence of water has recently been announced.

NASA also recently released amazing results from the Dawn mission about the asteroid Vesta. This asteroid was believed to be dry, since it was believed that asteroids are incapable of retaining water.

Yet the recent results provide evidence that Vesta may have had short-lived flows of water-mobilised material on its surface. These results make the asteroid very interesting as these characteristics were thought only to be present on planets. Who knows what interesting discoveries will be made with the upcoming rendezvous with Ceres?

MESSENGER to Mercury

Alver crater graces this image of Mercury’s limb. Secondary crater chains that scour the surface and lead toward the top right of the scene appear to be from the Rembrandt basin to the north.
NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The MESSENGER ((Mercury Surface, Space Environment, Geochemistry, and Ranging Mission) to Mercury was due to end in March 2015. Launched on August 3, 2004, it entered orbit around Mercury on March 17, 2011, for a one-year discovery mission, and has provided unprecedented views of the innermost planet.

A manoeuvre on January 21 increased the altitude of its orbit, prolonging the mission for possibly another month. Sometime in late April, the probe will descend and crash into the surface of Mercury.

Happy 25th Hubble

The Hubble Space Telescope in a picture snapped by a Servicing Mission 4 crewmember just after the Space Shuttle Atlantis captured Hubble with its robotic arm on May 13, 2009.
NASA

The Hubble Space Telescope turns 25 on April 25, 2015.

Launched into space on the Shuttle Discovery in 1990, and in spite of early problems and repairs over the years, it is still going strong. It is expected to continue through to 2018 when the James Webb Telescope is launched.

New Horizons

Artist’s concept of the New Horizons spacecraft as it approaches Pluto and its three moons in summer 2015.
Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute (JHUAPL/SwRI)

My favourite event will occur on July 14 when NASA’s New Horizons spacecraft flies by Pluto and Charon.

The probe left Earth in 2006, just after Pluto was demoted to being a dwarf planet. It will provide us with the first up close and personal images of this outer solar system object. Initial observations started in January, but the best views will occur as it flies by the dwarf planet on July 14 before heading off to visit other objects far out in the Kuiper Belt.

Rosetta

Mosaic of four images taken by Rosetta’s navigation camera on 22 January 2015 at 28.0 km from the centre of comet 67P/Churyumov-Gerasimenko.
ESA/Rosetta/NAVCAM, CC BY-SA

Rosetta successfully launched the Philae lander onto the surface of Comet 67P/Churyumov-Gerasimenko on November 2014 and continues to orbit the comet as it makes closest approach to the sun on 13 August 2015.

Rosetta’s mission is to monitor how the comet changes as it approaches the sun. It is hoped that the Philae lander, currently in hibernation, will wake up in the early months of the year as it gets more sunlight on its solar panels and again gather data.

Cassini meets Enceladus

This view looks across the region of Enceladus’ geyser basin and down on the ends of the Baghdad and Damascus fractures that face Saturn.
NASA/JPL-Caltech/Space Science Institute

In October NASA’s Cassini mission is scheduled to undertake a close flyby of Saturn’s moon Enceladus.

The flyby will allow the spacecraft to get close enough to fly through the geysers of water that have been discovered emanating from this very interesting icy moon and hopefully reveal secrets of a possible subsurface ocean.

Goodbye Voyager 2

Artist’s impression of Voyager departing our solar system and entering deep space.
NASA/JPL

2015 will also see Voyager 2 follow its younger sibling out past the edge of our solar system sometime during this year.

Both Voyager spacecraft were launched in 1977 and, with Pioneer 10, are now the most distant man-made objects in the solar system. While Pioneer 10, launched in 1972, has not been contactable since 2003, both Voyager probes continue to send information.

This is just a snapshot of some of the highlights of 2015, which is sure to be a momentous year in space exploration.

This article was originally published on The Conversation. (Reblogged by permission). Read the original article.

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