Tag Archives: Mercury

Comet, Earth and Mercury Seen Together in Rare Video

A new video from a NASA spacecraft studying the sun has captured an unexpected sight: a wandering comet posing with the planets Earth and Mercury.

The cosmic view comes from one of NASA’s twin Stereo spacecraft that constantly watch the sun for signs of solar flares and other space weather events. It shows Mercury and Earth as they appeared with the Comet Pan-STARRS, a comet that is currently visible from the Northern Hemisphere during evening twilight.

The probe captured the video of Comet Pan-STARRS, Earth and Mercury together while observing the sun from March 9 to March 12.

According to a NASA description, the video “shows the comet and its fluttering tail as it moves through space.” The Earth appears as a bright stationary object on the right side of the video, while Mercury is visible as a moving light on the left side.

The sun is actually out of the frame in the Stereo-B spacecraft’s video, but its solar wind is visible as a stream of material, NASA officials explained. Meanwhile, the view of Comet Pan-STARRS from space is giving scientists a wealth of data to review, they added.

“Comet scientists say the tail looks quite complex and it will take computer models to help understand exactly what’s happening in STEREO’s observations,” agency officials said in a video description. “The comet should remain visible to the naked eye through the end of March.”

Comet Pan-STARRS is currently visible to stargazers in the Northern Hemisphere just after sunset. To see the comet, look low on the western horizon just after the sun has gone down. Comet Pan-STARRS can appear as a bright head with a wispy trail, weather permitting, though some stargazers have said the bright evening twilight can make spotting it tricky.

The Comet Pan-STARRS was discovered in June 2011 by astronomers using the Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) in Hawaii. The comet’s official name is C/2011 L4 (PANSTARRS).

Scientists estimate that Comet Pan-STARRS takes more than 100 million years to orbit the sun once. The comet crossed into the Northern Hemisphere evening sky last week after months of being visible to observers in the Southern Hemisphere.

NASA’s twin Stereo A and B spacecraft (the name is short for Solar TErrestrial RElations Observatory) observe the sun in tandem to provide unparalleled views of how material from solar eruptions makes its way to Earth. The spacecraft launched in 2006 and are part of a fleet of sun-watching spacecraft that monitor solar storms.

Comet Pan-STARRS is one of several comets gracing the night sky in 2013. Pan-STARRS was joined by the Comet Lemmon earlier this year when both were visible together in the Southern Hemisphere sky. Later this year, the sungrazing Comet ISON could put on a potentially dazzling display when it makes its closest approach to the sun in late November.

Homepage image courtesy of Astronomy Education Services/Gingin Observatory

This article originally published at Space.com
here

Read more: http://mashable.com/2013/03/15/comet-earth-mercury-video/

Mark Your Calendar for Spring Meteor Showers and Eclipses

Lunar-eclipse

As the Moon passed almost directly through the center of Earth’s shadow on July 16th, sky gazers in the Pacific hemisphere were graced by a lingering lunar eclipse.

From eclipses and planets to meteor showers galore, the northern spring season of 2014 will bring a number of eye-catching celestial sights for stargazers on Earth.

Weather permitting, some of the best spring night sky events could be readily visible without the aid of binoculars or a telescope, even from brightly-lit cities. But you’ll need to know when and where to look to make the most of the season.

I’ve always felt that many astronomers started their careers as perceptive children who responded to the thrill of witnessing a noteworthy astronomical event. So whether you want to impress a youngster, or you’re simply hoping to witness a head-turning astronomical event for yourself, it always helps to be ready in advance by marking your calendar and highlighting a number of these special dates:

April 14 and 15: Mars’ closest approach in 2014 and a total eclipse of the moon

During the overnight hours of April 14 and 15, it will be a night for viewing first Mars and later the full moon.

First, Mars will come to within 57.4 million miles of our planet, making its closest approach to us since Jan. 3, 2008. All through the night, Mars will resemble a dazzling star shining with a steady fiery-colored tint making it a formidable sight; its brightness will match Sirius, the brightest of all the stars.

As a bonus, later that very same night (actually during the early hours of April 15) North America will have a ringside seat to see a total lunar eclipse when the Full Moon becomes transformed into a mottled reddish ball for 78 minutes as it becomes completely immersed in the shadow of the Earth.

This total lunar eclipse will be the first one widely visible from North America in nearly 3.5 years. The Americas will have the best view of this eclipse, although over the Canadian Maritimes, moonset will intervene near the end of totality. Of special interest is the fact that the moon will appear quite near to the bright star Spica, in the constellation Virgo, during the eclipse. They actually will be in conjunction a couple of hours prior to the onset of totality, but they’re still relatively near to each other when the eclipse gets underway.

April 22: The Lyrid meteor shower

Rather favorable circumstances are expected for this year’s Lyrid meteor shower, predicted to be at maximum this morning. The radiant, located near the brilliant bluish-white star Vega, rises in the northeast about the time evening twilight ends, and viewing will improve until light from the last-quarter moon begins to interfere just after 2 a.m. your local time.

Under the best conditions, 10 to 15 members of this shower can be seen in an hour by a single observer. The Lyrids remain about a quarter of their peak number for about two days. These bright meteors are associated with Thatcher’s Comet of 1861.

April 28 and 29: A Ring Eclipse that nobody will see?

It is quite possible that only penguins will witness the annular solar eclipse, also known as a “ring of fire” solar eclipse. That’s because it will occur within the uninhabited region of Wilkes Land in Antarctica.

Those living in southernmost parts of Indonesia as well as Australia (where it will be autumn) will at least get a view of a partial eclipse of the sun. Because the axis of the moon’s antumbral shadow misses the Earth and only its edge grazes Antarctica, it makes an accurate prediction of the duration of annularity all but impossible.

May 6: The Eta Aquarid meteor shower

The annual Eta Aquarid meteor shower — “shooting stars” spawned by the famed Halley’s Comet — is scheduled to reach maximum early this morning. It’s usually the year’s richest meteor display for Southern Hemisphere observers, but north of the equator the Eta Aquarid shower is one of the more difficult annual displays to observe.

From mid-northern latitudes, the radiant (from where the meteors appear to emanate) rises about 1:30 a.m. local daylight time, scarcely two hours before morning twilight begins to interfere. At peak activity, about a dozen shower members can be seen per hour by a single observer with good sky conditions from latitude 26 degrees North, but practically zero north of latitude 40 degrees. The shower remains active at roughly one-half peak strength for a couple of days before and after the maximum. Conditions this year are excellent; the moon is absent from the predawn sky for more than a week around maximum.

May 10: Saturn at opposition

The ringed planet Saturn reaches opposition; it rises in the east-southeast at dusk, is due south in the middle of the night and sets in the west-southwest at dawn. Once it gains enough altitude, it appears similarly as bright as the zero-magnitude stars Arcturus and Vega.

Saturn’s famous rings appear much more impressive than in recent years, since they are now tipped by 21.5 degrees from edge on.

May 24: Possible outburst of bright meteors

Perhaps the most dramatic sky event in 2014 could come at the start of the Memorial Day weekend. In the predawn hours of Saturday, May 24, our planet is expected to sweep through a great number of dusty trails left behind in space by the small comet P/209 LINEAR.

This unusual cosmic interaction might possibly result in an amazing, albeit brief display of meteors — popularly known as “shooting stars” — perhaps numbering in the many dozens . . . or even hundreds per hour. Nobody knows exactly how many meteors will be seen, but several meteor scientists believe that because the particles will be unusually large, the meteors will be outstandingly bright.

May 25: Mercury attains its greatest elongation

The planet Mercury will reach its greatest elongation, or greatest angular distance, east of the sun on this night. This is Mercury’s best evening apparition of the year; it sets about 100 minutes after sunset. An hour after sunset, look low above the west-northwest horizon; the speedy planet should be easily visible as a yellowish “star.”

Mercury will appear somewhat brighter up to two weeks before this date, and noticeably dimmer for about a week afterwards.

This article originally published at Space.com
here

Read more: http://mashable.com/2014/04/01/spring-stargazing-guide/

Scientists Discover Evidence of Mercury’s Explosive Volcanic History

Until recently, Mercury was not believed to contain the volatile elements required for making violent volcanic explosions. New data from the MESSENGER spacecraft has shown that this was not always the case. Not only was Mercury rife with volcanic activity early in the planet’s history, but it lasted much longer than anyone would have expected. The research comes from lead author Timothy Goudge from Brown University and was published in the Journal of Geophysical Research: Planets

Earth is filled with chemicals like water and carbon dioxide which have relatively low boiling points and facilitate volcanic explosions. As they get cycled through with lava and get closer to the surface, they change from liquid to gas and expand, building up pressure. Eventually, the pressure just becomes too great, and the gasses and lava explode into an eruption. 

Mercury, on the other hand, has not been thought to be as geologically exciting. When NASA’s MESSENGER probe began returning info about Mercury in 2008, scientists began to get the first clues of how dynamic the planet really is, or at least how it was. Some of the first images from the spacecraft revealed ash that is characteristic of volatile volcanic explosions. 

While it was then clear that Mercury had volcanic activity at one point, there was not yet enough information about the duration of that activity. The ash could have accumulated over long periods of volcanic activity, or there could have been a short-yet-hectic time period in which the volatile elements caused these eruptions on Mercury’s surface.

Goudge’s team focused on 51 sites that had this characteristic pyroclastic ash by analyzing the images and data collected from spectrometers. The team noted that not all of the vents had experienced the same level of erosion, indicating that this activity did not occur in a short, chaotic period. In fact, after using the erosion to estimate the age of the vents, some were only 3.5-1 billion years old. Because Mercury itself is 4.5 billion years old, this means that Mercury spent much of its existence as a very volatile place with large amounts of the gases that cause those explosive eruptions.

Understanding the former volcanic activity could give clues to how the first planet formed. Mercury’s iron core is much larger than what would be expected for a planet of that size. This has led some to believe that Mercury used to be much larger than it is now. The loss of its size could have been due to a massive collision, or perhaps the intense radiation from the sun could have blown the outer layers off over time. If this turns out to be the case, it would explain why Mercury no longer has the volatiles that are necessary for explosive volcanic activity.

Read more: http://www.iflscience.com/space/scientists-discover-evidence-mercury%E2%80%99s-explosive-volcanic-history

Incredible New Map Of Mercury Revealed

This has been a good week for Mercury. Millions of people around the world observed the little planet transit across the solar disk on Monday, and now NASA has released the first topographic model of the planet.

The digital elevation model (DEM) was constructed from data taken by the MESSENGER probes Mercury Laser Altimeter, and it shows a large variety of interesting features. The highest point on Mercury is 4.48 kilometers (2.78 miles) above the average elevation, with the lowest being 5.38 kilometers (3.34 miles) below average, found within the Rachmaninoff basin.

The MESSENGER mission studied Mercury from 2011 to 2015, and NASA has so far shared more than 10 terabytes of data, including nearly 300,000 images and millions of scientific measurements. Among the many discoveries madeby the probe was the first visual evidence of extensive volcanism in Mercury’s recent past.

A view of Mercurys northern volcanic plains from the new map areshown in enhanced color to emphasize different types of rocks on Mercurys surface. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

A map of the lava-covered terrain in the north pole of the planet was released together with the DEM. The lava deposit is about 2 kilometers (1.2 miles) thick and it covers an area equivalent to 60 percent of the continental United States. Another important feature of Mercurys north pole is the presence of organic molecules and water ice in its permanently shadowed craters.

This has become one of my favorite maps of Mercury, Nancy Chabot, one of MESSENGERs scientists, said in a statement.Now that it is available, Im looking forward to it being used to investigate this epic volcanic event that shaped Mercurys surface.

The latest information about Mercury was released by the Planetary Data System, whose job is to archive and distribute all of the data collected by NASAs missions to other planets. MESSENGERs mission ended last year when the probe was deorbited (as planned) and crashed on Mercury. While the mission is complete, there’s still muchhiding in the data.

MESSENGERs scientists and engineers hope that data from the mission will continue to be utilized by the planetary science community for years to come, not only to study the nature of the innermost planet, but to address broader questions about the formation and evolution of the inner Solar System more generally, added MESSENGER Principal Investigator Sean Solomon, director of Columbia Universitys Lamont-Doherty Earth Observatory.

Photo Gallery

Read more: http://www.iflscience.com/space/incredible-new-map-mercury

Mercury is shrinking

 
Over the past four billion years Mercury has shrunk by as much as 14 kilometers. The fact that this planet closet to the sun is shrinking isn’t the surprise; scientists have known about it since the 1970s. But new images show that the shrinkage is several kilometers more than they previously observed.
 
Mercury is a small, iron planet — about 5,000 kilometers across — with a thin rock crust and a large iron core that’s been cooling over billions of years. When an initially hot planet cools and contracts, geologic structures begin to form through the buckling and fracturing of the planet’s crust. The cliff-like faults and ridges that result from interior cooling and surface compression look like long ribbons from above. They range from 8 to 800 kilometers long and can be up to 2 kilometers high.
 
During three flybys in 1974 and 1975, Mariner 10, the first spacecraft sent to explore Mercury, gathered images of less than half the planet’s surface. These older images indicated that, despite cooling over its lifetime, the rocky planet had barely shrunk at all — maybe 1 or 2 kilometers in radius. But modeling of Mercury’s formation and aging couldn’t explain that finding: after all, as a liquid iron core turns solid over time, it contracts, and the planet should shrink, a lot.
 
In 2011, NASA’s MESSENGER spacecraft entered Mercury’s orbit, and it’s been collecting data on the entire planet ever since. (It’ll be completing its 2,900th orbit of Mercury later this month.) Using MESSENGER’s high-resolution, low-angle images and topographic data, a team led by Paul Byrne from the Carnegie Institution of Washington created a comprehensive map of the ridges and faults across the entire surface of the planet.
 
Mercury is basically a raisin. Lobate scarps are cliffs caused by thrust faults that have broken the surface. Wrinkle ridges are caused by faults that don’t extend as deep; surface materials from one side of the fault ramp up and fold over, forming a ridge. (Switching metaphors here, imagine a tailor making a series of tucks to take in dress or a pair of pants.) The team mapped a total of 5,934 of these tectonic features.
 
By adding up the total amount of crust displaced by the ridges and scarps, they found that the total contraction of Mercury’s surface is equivalent to a loss of 4.6 to 7 kilometers of the planet’s radius.
 
 
Finally, this greater estimate of shrinkage matches up with models that predict how much a rocky planet contracts as its metal interior cools. “This discrepancy between theory and observation, a major puzzle for four decades, has finally been resolved,” study coauthor Sean Solomon of Columbia University tells Forbes. “It is wonderfully affirming to see that our theoretical understanding is at last matched by geological evidence.”
 
In fact, the observed deformation of Mercury’s surface is consistent with a 19th-century theory for a shrinking Earth (now obsolete). We know that’s not true for our planet, since Earth’s outer shell is broken into multiple plates. But Mercury is enclosed by a single plate, so it doesn’t lose its heat through plate tectonics. All planets are cooling over time, but as far as we know, Earth is the only one that has tectonic plates instead of a single, outer shell. The findings provide a framework for understanding how one-plate planets cool — their thermal, tectonic and volcanic history — which is especially useful given the increasing number of rocky planets being found around other stars.
 
The findings were published in Nature Geoscience this week. 
 
 
Images: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington 
 

Photo Gallery

Read more: http://www.iflscience.com/space/mercury-shrinking

Mercury’s Surface Resembles Rare Meteorites

Mercury-s-surface-resembles-rare-meteorites-a96c11d2d9

Mercury has a surface unlike any other planet’s in the solar system, instead resembling a rare type of meteorite, researchers say.

The finding, based on an analysis of data from NASA’s Messenger probe, sheds new light on the formation and history of the mysterious innermost planet, scientists add.

Mercury, the smallest planet in the solar system, is also one of the least understood, having received much less attention from scientific missions than Mars, Jupiter and Saturn. NASA set out to change that when it launched the Messenger probe a little more than eight years ago. Messenger became the first spacecraft to orbit Mercury.

Past research based on Messenger data suggested a vast part of Mercury is covered with hardened lava, enough to bury the state of Texas under 4 miles of once-molten rock, scientists said. All in all, these mammoth floods of lava cover 6% of the planet’s surface, an area equal to nearly 60% of the continental United States. They created Mercury’s smooth northern plains between 3.5 billion to 4 billion years ago.

(SPACE.com)

Lava plains are common in the solar system. For instance, young Mars spewed lava all across its surface, and it still has the largest volcano in the solar system: Olympus Mons is about 370 miles in diameter, wide enough to cover the entire state of New Mexico, and 16 miles high, three times taller than Mount Everest.

Now, 205 measurements of Mercury’s surface composition, made by the X-ray spectrometer onboard Messenger, reveal how much Mercury’s surface differs from those of other planets in the solar system.

“Being the closest planet to the sun does mean its formation history would be different and more extreme than the other terrestrial planets, with hotter temperatures and exposure to a stronger gravitational field,” says lead study author Shoshana Weider, a planetary geologist at the Carnegie Institution of Washington.

The surface is dominated by minerals high in magnesium and enriched in sulfur, making it similar to partially melted versions of an enstatite chondrite, a rare type of meteorite that formed at high temperatures in low-oxygen conditions in the inner solar system.

“The similarity between the constituents of these meteorites and Mercury’s surface leads us to believe that either Mercury formed via the accretion of materials somewhat like the enstatite chondrites, or that both enstatite chondrites and the Mercury precursors were built from common ancestors,” Weider said.

The researchers also looked at the areas around the northern volcanic plains. These surrounding locales are more pockmarked by craters, suggesting they are older, with more time spent getting scarred by meteor impacts.

The older terrain possesses higher ratios of magnesium to silicon, sulfur to silicon and calcium to silicon than the northern plains do, but it also has lower ratios of aluminum to silicon. These differences suggest the smooth plains came from magma sources that were chemically different from the source of the material seen in the older regions.

“The chemical differences between the northern plains and the surrounding areas, combined with the fact that the northern plains are younger by about 500 million years, tells us that the volcanic activity which produced the northern plains involved melting of different sections of Mercury’s mantle, at cooler temperatures and at a later stage in the planet’s history than the activity that would have produced the older surrounding terrains,” Weider said.

The scientists will detail their findings in an upcoming issue of the Journal of Geophysical Research-Planets.

Image courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

This article originally published at Space.com
here

Read more: http://mashable.com/2012/09/24/mercury-surface-meteorites/

Mercury, Venus, Mars, Jupiter and Saturn Are About To Align

This month will see a passing moment where Mercury, Venus, Mars, Jupiter, and Saturn the five planets visible from Earth by the naked eye will appear in a line from the horizon to the Moon.

The alignment of these five earthly neighbors will be visible from Wednesday, January 20 to Saturday, February 20.

Dr. Tanya Hill, senior curator at the Melbourne Planetarium, told Australian Geographicthat if you don’t catch the allignment this month, youllbe able to see it again in August of this year, and then again in October 2018.

Dr. Alan Duffy, research fellow at Swinburne University in Melbourne, also spoke to Australian Geographic and gave some advice on how best to see the alignment.

Since Mercury will appear very close to the horizon, find a nice open spot, away from tall buildings or trees. Getting as far away from city lights is also advisable, so each planet’s glow isn’t too drowned out by light pollution.

Venus and Jupiter, however, should be fairly easy to spot and Mars distinctive red glow should give itself away. If you can find one of these planets, just hold up your arm so its in line with it and the Moon the rest should fall vaguely in line with your arm.

There are only a few amazing things in the night sky that can be seen without any equipment, Dr. Duffy said, adding that this is something well worth seeing.

Read more: http://www.iflscience.com/space/mercury-venus-mars-jupiter-and-saturn-are-about-align

See Saturn, Mercury, Venus, Mars and More This Month

Telescope

Image: Flickr, Ryan Wick

The July night sky is filled with planets to the delight of stargazers and astronomers, but you’ll have to know when and where to look to get your summer solar system fix.

All through July, the planet Mars and the bright star Spica glow in the west-southwest sky during the evening hours. Saturn, the so-called “Lord of the Rings,” can be found to that pair’s left and will climb a bit higher (and set a bit later) each night.

Toward the end of the night this month, Venus and Mercury rise up in the dawn twilight above the east-northeast horizon, just ahead of the sun. The only bright planet “out of the loop” this month is Jupiter, which will be too near to the sun to be visible through July.

To help you make the most of your stargazing nights in July, we’ve rounded up the most promising planetary sights to behold with telescopes, binoculars and the unaided eye. To help locate your targets, you can use your clenched fist at arm’s length — equal to roughly 10 degrees — to measure off angular distances. The brightest stars in the sky are ranked as first or zero magnitude on the brightness scale used by astronomers. The very brightest objects (Venus, moon and sun) are of negative magnitude.

Here’s a look at when to see the brightest planets in the July night sky (note that all skywatching is dependent on your local weather conditions):

July 5: Hovering just above the moon as darkness falls on this Saturday evening is Mars, which shines brightly in the south-southwest sky at dusk, outshone in luster only by the similarly hued star Arcturus (high in the southwest) and bluish Vega (high in the northeast). As the sky darkens further, the nearby blue star Spica becomes prominent about 4 degrees to the lower left. After Mars passes to the north of Spica on July 13, we’ll be able to watch the Red Planet withdrawing eastward of the star quite rapidly. July is the last month that Mars will show more than a few traces of surface features in medium-size telescopes on good nights. On July 2, the planet will have receded to 1 astronomical unit (93 million miles or 150 million kilometers) from Earth.

July 7: Saturn appears as a bright yellowish-white “star” shining sedately 1.3 degrees above and to the left of the gibbous moon this evening. Almost everyone remembers his or her first view of Saturn. The magnificent ring system, the banded globe, and the faintly shimmering moons make Saturn an object of exquisite beauty. The rings are currently tilted 21 degrees toward our line of sight, the least this year. To clearly discern them you’ll need a telescope with magnifying capabilities of at least 30-power; a 4-inch refractor or 6-inch reflector at 150-power are probably the minimum apertures and magnification suitable for making detailed studies of this planet.

July 12: Mercury arrives at its greatest elongation this morning, 21 degrees west of the sun. Look for it about 45 minutes before sunrise appearing as a bright “star” in the brightening twilight shining about 8 degrees below and to the left of brilliant Venus. Over the next two weeks, Mercury brightens noticeably and pulls slowly away from Venus while moving closer to the sun.

July 13: Mars slides north of Spica this evening, this being the third and final conjunction in a series of three (a “triple conjunction”).  Mars previously passed this star on Feb. 3 and March 25, but this conjunction is the closest of the three; planet and star are separated by just 1.3 degrees. The contrast between yellow-orange Mars and bluish Spica is striking.

July 24: Venus, the “morning star,” rises at first light and shines low in the east-northeast as dawn brightens. This morning, you’ll also see a delicately thin crescent moon hovering about 4 degrees to its left. In a telescope, Venus is just a tiny, gibbous blob. It has shrunk and become more nearly round in recent months as it has swung far around to the back side of the sun as seen from Earth. In addition, don’t forget Mercury. It appears noticeably lower above the east-northeast horizon compared to earlier in the month, but has brightened up to magnitude -1 and is visible about 10 degrees to the lower left of crescent moon.

Also today, Jupiter comes to conjunction with the sun; it’s on the far side of the sun during July and can’t be seen.

This article originally published at Space.com
here

Read more: http://mashable.com/2014/07/04/5-planetary-events-july/

Water Ice Discovered on Mercury

Water-ice-discovered-on-mercury-cf97d9f478

It’s time to add Mercury to the list of worlds where you can go ice-skating. Confirming decades of suspicion, a NASA spacecraft has spotted vast deposits of water ice on the planet closest to the sun.

Temperatures on Mercury can reach 800 degrees Fahrenheit (427 degrees Celsius), but around the north pole, in areas permanently shielded from the sun’s heat, NASA’s Messenger spacecraft found a mix of frozen water and possible organic materials.

Evidence of big pockets of ice is visible from a latitude of 85 degrees north up to the pole, with smaller deposits scattered as far away as 65 degrees north.

The find is so enticing that NASA will direct Messenger’s observation toward that area in the coming months — when the angle of the sun allows — to get a better look, said Gregory Neumann, a Messenger instrument scientist at NASA’s Goddard Space Flight Center in Maryland.

“There is an ongoing campaign, when the spacecraft permits, to look further northward,” said Neumann, the lead author of one of three Mercury studies published online in the Nov. 29 edition of the journal Science.

Researchers also believe the south pole has ice, but Messenger’s orbit has not allowed them to obtain extensive measurements of that region yet.

Messenger will spiral closer to the planet in 2014 and 2015 as it runs out of fuel and is perturbed by the sun’s and Mercury’s gravity. This will let researchers peer closer at the water ice as they figure out how much is there.

Similarities to the Moon

Speculation about water ice on Mercury dates back more than 20 years.

In 1991, Earth-bound astronomers fired radar signals to Mercury and received results showing there could be ice at both poles. This was reinforced by 1999 measurements using the more powerful Arecibo Observatorymicrowave beam in Puerto Rico. Radar pictures beamed back to New Mexico’s Very Large Array showed white areas that researchers suspected was water ice.

A closer view, however, required a spacecraft. Messenger settled into Mercury’s orbit in March 2011, after a few flybys. Almost immediately, NASA used a laser altimeter to probe the poles. The laser is weak — about the strength of a flashlight — but just powerful enough to distinguish bright icy areas from the darker, surrounding Mercury regolith.

Neumann said the result was “curious”: There were few bright spots inside craters.

Team member John Cavanaugh was pretty sure of what they were finding, Neumann recalled. Cavanaugh had been a part of NASA’s Lunar Reconnaissance Orbiter team, and he had seen a similar strange pattern on Earth’s moon when LRO found ice at the lunar poles in 2009.

Flash heating on Mercury would mix nearly all of its ice with the surrounding regolith – as well as with possible organic material borne to the planet by comets and ice-rich asteroids.

“So what you’re seeing is the fact that water ice can’t survive indefinitely in these locations because the temperatures apparently spike up,” Neumann said.

Organics the Big Surprise

The team expected to find water ice on Mercury. Indeed, Messenger already drew a linkthis year between permanently shadowed areas on the planet and the “radar bright” spots seen from Earth.

All researchers needed to do was point their instruments in the right spot, seek out bright areas and then measure the temperature and composition.

Messenger’s neutron spectrometer spotted hydrogen, which is a large component of water ice. But the temperature profile unexpectedly showed that dark, volatile materials – consistent with climes in which organics survive – are mixing in with the ice.

“This was very exciting. You are looking for bright stuff, and you see dark stuff – gee, it’s something new,” Neumann said.

Organic materials are life’s ingredients, though they do not necessarily lead to life itself. While some scientists think organics-bearing comets sparkedlife on Earth, the presence of organics is also suspected on airless, distant worlds such as Pluto. Scientists say comets carrying organic bits smashed into other planets frequently during the solar system’s history.

Researchers are now working to determine if they indeed saw organics on Mercury. So far, they suspect Mercury’s water ice is coated with a 4-inch (10 centimeters) blanket of “thermally insulating material,” according to Neumann’s paper.

It will take further study to figure out exactly what this material is, but Neumann said the early temperature curves could show organic materials such as amino acids.

This article originally published at Space.com
here

Read more: http://mashable.com/2012/11/29/mercury-water-ice/

The More We Learn About Mercury, The Weirder It Seems

For such a tiny planet, Mercury is a pretty big puzzle for researchers. NASAs MESSENGER probe already has revealed that the planet is surprisingly rich in elements that easily evaporate from the surface, such as sulphur, chlorine, sodium and potassium. This is incredibly odd as these kind of substances most likely would disappear during a hot or violent birth exactly the type of birth a planet so close to the sun, such as Mercury, would have had.

Scientists are also struggling to understand why Mercury is so dark and what its earliest planetary crust, created as the newly-formed planet cooled down, was made of. Research has now started to throw up answers but these are raising a lot of new questions.

In search of the oldest crust

Look at the moon and youll see dark lava flows that have been erupted over the brighter-looking terrain of the lunar highlands. The highlands are the moons oldest crust and were formed from a pile up of crystals called anorthite, which rose to the top of the global magma ocean that covered the moon in the aftermath of its violent birth.

Part of the Moon, with dark lava flows overlying bright (high albedo) primary crust. NASA/GSFC/Arizona State University/Quickmap

But if you look at Mercury as seen during during MESSENGERs 2011-2015 orbital campaign youll see no such thing. Mercury is dark everywhere. Its crust is mostly a series of giant lava sheets and the older ones have been around long enough to be scarred by a large number of impact craters created by comets and asteroids bombarding the surface.

2000 km wide area of Mercury. Unlike the Moon, it is all dark. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Quickmap

All those lava sheets must have been erupted on top of something so where is Mercurys oldest crust, and what was it made of? This is a problem that Mercury scientists have been grappling with since MESSENGER made its first flyby in 2008. They identified some particularly dark patches, dubbed low reflectance material, which apparently have been dug up to the surface as comets and asteroids hit it. But they could not work out what makes this material so dark, especially as MESSENGER proved that Mercurys surface is remarkably poor in iron, which could have darkened it.

However, it turns out that a lack of iron would make Mercurys original magma ocean less dense than the moons, so that any anorthite crystals that grew would sink rather than floating upwards to produce bright spots. In fact, the only mineral likely to crystallise that would have been able to float is graphite, the soft, dark form of carbon used in pencil lead.

Weird composition

A graphite crust on Mercury used to seem unlikely, especially if you assume that its carbon content is similar to that of the Earth or Mars. But now research suggests that this crust was indeed made largely out of graphite. That is strange because the other rocky planets have a lot less carbon on their surfaces, and carbonaceous asteroids from which a carbon-rich planet could form are much further from the sun than Mercurys present orbit.

The study analysed data collected by MESSENGER when the spacecraft was within 100 km of the surface. It showed that while the dark patches did contain graphite, it was far from being pure more like ordinary rock debris with a few percent of graphite mixed into it.

The 500 km wide Tolstoj basin, centre right, that exposes a dark ring of low reflectance material. The 75 km crater Basho, lower left, whose innermost ejecta is also low reflectance material. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

So, we still have not found any of Mercurys primary crust exposed at the surface in an intact state, though we may have found the next best thing: the impact-pummelled surface of the original crust, dug out by later impacts. The original crust was overprinted by successive episodes of volcanism. There are also clear traces of much more recent hollows where the surface has been eaten away by some process that removed solid volatile substances such as sulfur, chlorine, sodium and potassium as vapour.

280 km wide view with an explosive volcanic vent just to the right of centre. The vent is surrounded by a pale, yellowish deposit that was erupted from it. NASA/JHUAPL/Carnegie Institute Washington

Most hollows are on or close to patches of low-reflectance material, so the primary crust itself could have been rich in these unlikely volatiles originally.

Scarlatti crater on Mercury. This exposes low reflectance material to the south of its peak-ring. The inset on the right, an area less than 5 km across, shows hollows forming there. NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

MESSENGER returned enough data to keep scientists busy for years to come, but to learn more about the crust and to work out exactly why the planet is so rich in strange elements we will probably have to await the arrival of the European Space Agencys BepColombo mission to Mercury in 2024.

Meanwhile, people across most of the globe will have an excellent chance to see Mercury for themselves when it crosses the face of the Sun (a solar transit) on 9 May 2016.

Read more: http://www.iflscience.com/space/more-we-learn-about-mercury-weirder-it-seems