Snow on Mercury?

No, not that kind of snow, but scientists say deep inside the planet Mercury, iron “snow” forms and falls toward the center of the planet, much like snowflakes form in Earth’s atmosphere and fall to the ground. The movement of this iron snow could be responsible for Mercury’s mysterious magnetic field, and Mercury may be the only body in our solar system where this occurs.

Mercury and Earth are the only local terrestrial planets that possess a global magnetic field. But Mercury’s is about 100 times weaker than Earth’s, which scientists have been unable to explain.

Made mostly of iron, Mercury’s core is also thought to contain sulfur, which lowers the melting point of iron and plays an important role in producing the planet’s magnetic field.

To better understand the physical state of Mercury’s core, the researchers in a lab recreated the conditions believed to exist at Mercury’s core, and melted an iron-sulfur mixture at high pressures and high temperatures.

In each experiment, an iron-sulfur sample was compressed to a specific pressure and heated to a specific temperature. The sample was then quenched, cut in two, and analyzed with a scanning electron microscope and an electron probe microanalyzer.

As the molten, iron-sulfur mixture in the outer core slowly cools, iron atoms condense into cubic “flakes” that fall toward the planet’s center, said Bin Chen, University of Illinois graduate student and lead author of a paper published in the April issue of Geophysical Research Letters. As the iron snow sinks and the lighter, sulfur-rich liquid rises, convection currents are created that power the dynamo and produce the planet’s weak magnetic field.

The researchers say their findings provide a new context for the data that will be obtained from NASA’s MESSENGER spacecraft, which will flyby Mercury for a second time on October 6, 2008. It will pass by the planet again in September of 2009, and go into orbit in March of 2011.

Original News Source: Eureka Alert

Here are some interesting facts about Mercury.

Could Jupiter Wreck the Solar System?

Could Jupiter throw the planets into eachother? (NASA)

Scientists have expressed their concern that the Solar System may not be as stable as it seems. Happily orbiting the Sun, the eight planets (plus Pluto and other minor planets) appear to have a high degree of long-term gravitational stability. But Jupiter has a huge gravitational influence over its siblings, especially the smaller planets. It appears that the long-term prospects for the smallest planet are bleak. The huge gravitational pull of Jupiter seems to be bullying Mercury into an increasingly eccentric death-orbit, possibly flinging the cosmic lightweight into the path of Venus. To make things worse, there might be dire consequences for Earth…

Jupiter appears to be causing some planetary trouble. This gas giant orbits the Sun at a distance of approximately 5 AU (748 million km), that’s five times further away from the Sun than the Earth. Although the distance may be huge, this 318 Earth-mass planet’s gravitational pull is very important to the inner solar system planets, including tiny Mercury. Mercury orbits the Sun in an elliptical orbit, ranging between 0.47 AU (at aphelion) to 0.31 AU (at perihelion) and is only 0.055 Earth masses (that’s barely five-times the mass of our Moon).

Running long-term simulations on the orbits of our Solar System bodies, scientists in France and California have discovered something quite unsettling. Jacques Laskar of the Paris Observatory, as well as Konstantin Batygin and Gregory Laughlin of the University of California, Santa Cruz have found that Jupiter’s gravity may perturb Mercury’s eccentric orbit even more. So much so their simulation predicts that Mercury’s orbit may extend into the path of Venus; or it might simply fall into the Sun. The researchers formulate four possible scenarios as to what may happen as Mercury gets disturbed:

  1. Mercury will crash into the Sun
  2. Mercury will be ejected from the solar system altogether
  3. Mercury will crash into Venus
  4. Mercury will crash into Earth

The last option is obviously the worst case scenario for us, but all will be bad news for Mercury, the small planet’s fate appears to be sealed. So what’s the likelihood Mercury could crash into the Earth? If it did, the asteroid that most likely wiped out the dinosaurs will seem like a drop in the ocean compared with a planet 4880 km in diameter slamming into us. There will be very little left after this wrecking ball impact.

But here’s the kicker: There is only a 1% chance that these gravitational instabilities of the inner Solar System are likely to cause any kind of chaos before the Sun turns into a Red Giant and swallows Mercury, Venus, Earth and Mars in 7 billion years time. So, no need to look out for death-wish Mercury quite yet… there’s a very low chance that any of this will happen. But some good news for Mars; the researchers have also found that if the chaos does ensue, the Red Planet may be flung out of the Solar System, possibly escaping our expanding Sun. So, let’s get those Mars colonies started! Well, within the next few billions of years anyhow…

These results by Batygin and Laughlin will be published in The Astrophysical Journal.

Source: Daily Galaxy

Here are some facts on Mercury.

Mercury is Less Like the Moon than Previously Believed


With Mercury fading in MESSENGER’s rear view mirror, scientists are just starting to pore through the torrent of images sent back. And as you can probably guess, the new mysteries are piling up fast and furious. The planet is much less like the Moon than scientists previously thought.

MESSENGER made its closest approach to Mercury on January 14, passing just a few hundred kilometres above its surface. During the flyby it captured a total of 1,213 images.

One of the most unique features discovered by MESSENGER has been dubbed “The Spider” by scientists. And that’s what it looks like. The feature has a central crater surrounded by more than a hundred narrow, flat-floored troughs (called graben) radiating away.

Unlike the Moon, Mercury has huge cliffs or scarps, which can snake hundreds of kilometres across the planet’s surface. They trace the lines of old volcanic faults, from when the planet was still geologically active.

Because of its small size and high density, Mercury has a surprisingly large pull of gravity. Astronauts walking around its surface would experience 38% of the Earth’s gravity. This higher gravity means that the impact craters look different. Material doesn’t splash out from the impact craters so far, and there are many more secondary crater chains.

“We have seen new craters along the terminator on the side of the planet viewed by Mariner 10 where the illumination of the MESSENGER images revealed very subtle features. Technological advances that have been incorporated in MESSENGER are effectively revealing an entirely new planet from what we saw over 30 years ago,� said Science Team Co-Investigator Robert Strom, professor emeritus at the University of Arizona and the only member of both the MESSENGER and Mariner 10 science teams.

MESSENGER wasn’t just taking pictures. It also had a suite of scientific instruments measuring many features of the planet. Perhaps the most puzzling of these is its magnetic field. Even though Mercury cooled down and solidified eons ago, it still has an magnetic field. This was first detected by Mariner 10, and MESSENGER confirmed it.

This is just the beginning. MESSENGER will return to Mercury on October 6, 2008 to make a second flyby, and then a third on September 29, 2009. The spacecraft make its final return to the planet on March 18, 2011 when it’ll begin a year-long orbital mission.

Original Source: MESSENGER News Release

Mercury in Living Color

The MESSENGER science team released more pictures from the Jan. 14 flyby, including what we’ve all been waiting for, the first one in color! But if you’re looking for spectacular, eye-catching color, well, sorry, its just not part of Mercury’s make-up.

The color image was created by combining three separate images taken through MESSENGER’s Wide Angle Camera (WAC) filters in the infrared, far red, and violet wavelengths (red, green, and blue filters for this image.) MESSENGER’s eyes can see far beyond the color range of the human eye, and the colors seen in this image are somewhat different from what a human would see.

Creating a false-color image in this way brings out color differences on Mercury’s surface that cannot be seen in the black and white images released earlier.

The WAC has 11 narrow-band color filters, in contrast to the two visible-light filters and one ultraviolet filter that were on Mariner 10’s camera. By combining images taken through different filters in the visible and infrared, the MESSENGER data allow Mercury to be seen in a variety of high-resolution color views not previously possible. This visible-infrared image shows an incoming view of Mercury, about 80 minutes before MESSENGER’s closest pass of the planet from a distance of about 27,000 kilometers (17,000 miles).

I love this image of Mercury’s south pole limb. It shows the terminator; the transition from the sunlit, day side of Mercury to the dark, night side of the planet. In the region near the terminator, the sun shines on the surface at a low angle, causing the rims of craters to cast long shadows, which brings out the height differences of the surface features. This image was acquired about 98 minutes after MESSENGER’s closest approach to Mercury, when the spacecraft was at a distance of about 33,000 kilometers (21,000 miles).

Mercury Spectra.  Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Laboratory for Atmospheric and Space Physics, University of Colorado
And here’s one for the scientist in you: the first data returned from MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer (MASCS). What the image on the right shows with the bar-graph type lines is a high-resolution spectra of the planet’s surface in ultraviolet, visible, and near-infrared light. The image on the left shows a portion of the ground-track along which the MASCS instrument took over 650 observations of the surface. The area is about 300 kilometers (190 miles) across. For those of you not fluent in spectra-ese, this shows the relative amount of sunlight reflected from the surface at wavelengths from the ultraviolet to the visible (rainbow) to the infrared.

Original News Source: MESSENGER Press Releases

Most Advanced Ion Engines For 2013 BepiColombo Mission to Mercury


British scientists have been given the green light to begin the development of the most advanced ion engines ever to be used in space travel history. Set for launch in 2013, the European/Japanese BepiColombo mission to Mercury will be propelled to the Solar System’s innermost planet by advanced ion engines, with an efficiency equivalent to 17.8 million miles per gallon. This is one very cheap spaceship to fly!

We are currently being dazzled and amazed at the sheer detail of the images being transmitted by NASA’s MESSENGER mission flyby of the tiny planet Mercury. While we watch and wait for MESSENGER to eventually establish an orbit (insertion should occur in the spring of 2011), UK scientists, working with the ESA and Astrium (Europe’s largest space contractor), are hard at work designing the engines for the next big mission to the inner Solar System: BepiColombo. The mission consists of two orbiters: the Mercury Planetary Orbiter (MPO), to carry out mapping tasks over the planet, and the Mercury Magnetospheric Orbiter (MMO), to characterize the planets mysterious magnetosphere. The two craft will travel as one for the 6 year journey to Mercury, but separate at orbital insertion.
ESAs BepiColumbo planned orbital configuration around Mercury (credit: ESA)
Although BepiColombo will use the gravitational pull of the Moon, Earth, Venus and then Mercury to actually get it to its destination, a large amount of energy is required to slow the craft down, countering the Sun’s gravity. Without an engine to thrust against BepiColombo‘s decent into the huge gravitational pull of the Sun, the mission would be doomed to overshoot Mercury and fall to a fiery end. This is where the ion engines come in.

Ion engines have been used in space missions before (such as the SMART-1 mission to the Moon in 2003), but the new generation engines currently undergoing development for the next Mercury mission will be far more efficient while providing sufficient thrust. Better efficiency means less fuel. Less fuel means less mass and volume, saving on launch cost and allowing more room for scientific instrumentation.

Ion engines work by channeling electrically charged particles (ions) through an electric field. Doing this accelerates the ions to high velocities. Each particle has a mass (albeit tiny), so each particle also carries a momentum when fired from the engine. Shoot enough particles out of the engine and you produce a thrust the spacecraft can use to accelerate or (in the case of BepiColombo) slow down. Ion engines do have a drawback. Although they are fuel efficient, the thrust can be small, so missions can take longer to complete; time must be allowed for the long-term thrust to have an effect on the velocity of the spacecraft. However, this shortfall for ion propulsion won’t deter space scientists from using this new technology, as the pros definitely outweigh the cons.

So, we can now look forward to over a decade of exploration of Mercury by MESSENGER and BepiColombo, one of the most uncharted and mysterious planets to orbit the Sun.


More Images of Mercury are Pouring In

True color image of Mercury (MESSENGER)

Even though the Mercury flyby happened earlier this week, you can look forward to days and days of images. I’m nowhere near finished being amazed and entertained by the deluge of images captured by MESSENGER.

This latest image was captured when MESSENGER was about 20 minutes from its closest approach – at a range of 5,000 km (3,100 miles) of the tiny planet. The image is so crisp and clear that features as small as 400 metres (0.25 miles) across can be distinguished.

The large crater is located near Mercury’s equator on the side of the planet newly imaged by MESSENGER. I’m guessing it has no name, since it’s never been seen before! Around the crater are hundreds of smaller, secondary impactors. Some of these create long linear chains that look like machine gun fire. These occur when an asteroid or comet is torn apart by gravity, and then rain down on the planet in a straight line.

By counting craters that sit on top of the large crater’s ejecta blanket, and then comparing this count to the ones inside the crater, scientists will be able to calculate how old the crater is, and when it was formed.

Mission controllers also announced that they’ve received all 500 megabytes of data captured by MESSENGER as part of the flyby. The spacecraft has sent back a total of 1,213 images from its Mercury Dual Imaging System cameras.

They also revealed details about the flyby. According to their calculations, the spacecraft missed the targeted aim point by about 8.25 km (5.12 miles). This still give MESSENGER the gravity assisted speed boost it needs to meet up with the planet again and eventually go into orbit.

Original Source: MESSENGER News Release

A View of Mercury’s Far Side


Images and data are arriving from MESSENGER’s recent flyby of Mercury. Scientists from NASA and the Johns Hopkins Applied Physics Lab are pouring over high resolution images of the side of the planet that has never before been imaged by a spacecraft. From these images, planetary geologists can study the processes that have shaped Mercury’s surface over the past 4 billion years. Let’s take a look at some of the images snapped by MESSENGER on January 14:

This image was taken just 21 minutes after MESSENGER’s closest approach to Mercury, at a distance of only 5,000 kilometers (3600 miles). It shows a region about 170 km (100 miles) across. Visible are a variety of surface features, including craters as small as about 300 meters (about 300 yards) across. But the most striking part of the image is one of the highest and longest cliffs yet seen on Mercury. About 80 km (50 miles) long, it curves from the bottom center up across the right side of this image. Scientists say that great forces in Mercury’s crust must 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 cliff near the top of the image.

MESSENGER at Mercury.  Image Credit:  Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This image shows a previously unseen crater with distinctive bright rays of ejected material from the impact extending outward, providing a look at minerals from beneath Mercury’s surface. A chain of craters nearby is also visible. Studying impact craters provides insight into the history and composition of Mercury. The width of the image is about 370 kilometers (about 230 miles), and was taken about 37 minutes after MESSENGER’s closest approach. This image is the 98th in a set of 99 images that were taken to create a large, high-resolution mosaic of this region of Mercury. Hopefully this anticipated mosaic will be released at a planned press conference on January 30.

MESSENGER at Mercury.  Image Credit:  Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
As MESSENGER approached Mercury on January 14, 2008, about 56 minutes before the spacecraft’s closest encounter, the Narrow-Angle Camera captured this view of the planet’s rugged, cratered landscape illuminated by the Sun. Although this crater has been imaged before by Mariner 10, MESSENGER’s modern camera has revealed detail that was not well seen by Mariner including the broad ancient depression overlapped by the lower-left part of the Vivaldi crater. Its outer ring has a diameter of about 200 kilometers (about 125 miles). The image shows an area about 500 km 9300 miles) across and craters as small as 1 kilometer (0.6 mile) can be seen. It was taken from a distance of about 18,000 km (11,000 miles.)

The MESSENGER (Mercury Surface Space Environment Geochemistry and Ranging) Science Team has begun analyzing these high-resolution images to unravel the history of Mercury, as well as the history of our solar system.

Original News Source: MESSENGER Website

Nobody Has Ever Seen This Side of Mercury


Even though spacecraft have visited Mercury in the past, the same hemisphere was always in sunlight for every encounter. One side was photographed, and the other side was a complete and total mystery. There could be a big smiley face there, and we’d never know it. Well, the mystery’s over. MESSENGER flew past Mercury on January 14th, 2008, and revealed the planet’s hidden side… mostly.

Mariner 10 was the first spacecraft to zip past the planet Mercury, making three flybys in 1974 and 1975. Because the same hemisphere was in sunlight, the spacecraft was only able to image half the planet.

On January 14th, 2008, NASA’s MESSENGER spacecraft captured this image of Mercury when it was about 27,000 km (17,000 miles) away from the planet. During this flyby, it filled in about half of the hemisphere missed by Mariner 10. So that means that there are still some parts hidden – waiting to be revealed in future flybys.

And so, did it see a smiley face? Nope. The hidden hemisphere was pretty much like the rest of Mercury revealed so far: craters, ridges, bright and dark regions. At the upper right is the giant Caloris basin; its western regions haven’t been seen by spacecraft before.

If you’re hoping for more photos, don’t worry. This is just a quick black-and-white image captured by MESSENGER. NASA is planning to release more detailed images, including colour photographs over the next few days, so stay tuned.

We’ll keep posting them as they’re released.

Original Source: MESSENGER News Release

A Winged MESSENGER Flies By Mercury


On January 14 the MESSENGER spacecraft skimmed just 200 kilometers (124 miles) above the surface of Mercury in the first of three flybys of the planet. Today (Jan. 15) the spacecraft will turn back towards the Earth to start down-linking the on-board stored science data it acquired during the flyby. The probe’s equipment gathered data on the mineral and chemical composition of Mercury’s surface, its magnetic field, its surface topography and its interactions with the solar wind. “This was fantastic,” said Michael Paul, a mission engineer. “We were closer to the surface of Mercury than the International Space Station is to the Earth.”

The closest approach was on the planet’s night side, the side facing away from the sun, and the spacecraft flew in the region along the equator. The scientific results will be available for the public at the end of January.

“The engineers and operators pulled off a tremendous feat, acquiring and locking onto the downlink signal from the spacecraft within seconds, providing the necessary Doppler measurements for the Radio Science team.” said MESSENGER Mission Systems Engineer Eric Finnegan, of the Applied Physics Lab in Laurel, Maryland. “The spacecraft is continuing to collect imagery and other scientific measurements from the planet as we now depart Mercury from the illuminated side, documenting for the first time the previously unseen surface of the planet.”

The signal from the spacecraft is tracked by the Deep Space Network, an international network of antennas that supports space missions.

In addition to Monday’s rendezvous, MESSENGER is scheduled to pass Mercury again this October and in September 2009, using the pull of the planet’s gravity to guide it into position to begin a planned yearlong orbit of the planet in March 2011. By the time the mission is completed, scientists also hope to get answers on why Mercury is so dense, as well as determine its geological history and the structure of its iron-rich core and other issues.

MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging. Launched in 2004, it already has flown past Venus twice and Earth once on its way to Mercury.

Only one spacecraft has previously visited Mercury. Mariner 10 flew past the planet three times in 1974 and 1975, and mapped about 45 percent of its surface.

With Pluto now considered a dwarf planet, Mercury is the solar system’s smallest planet, with a diameter of 3,032 miles, about a third that of Earth.

A surface feature of great interest to scientists is the Caloris basin, an impact crater about 800 miles in diameter, one of the biggest such craters in our solar system. It likely was caused when an asteroid hit Mercury long ago. Scientists hope to learn about the subsurface of the planet from studying this crater.

True to its name, temperatures on the closest plant to the sun are quite “mercurial,” as Mercury experiences the largest swing in surface temperatures in our solar system. When its surface faces the sun, temperatures hit about 800 degrees Fahrenheit (425 Celsius), but when its faces away from the sun they can plummet to minus-300 Fahrenheit (minus-185 Celsius).

Original News Source: Reuters

MESSENGER Flyby of Mercury January 14th


If you thought you were good at pool, think again: in a game of interplanetary billiards, the MESSENGER team has guided its spacecraft to pass by Mercury for the first time on Monday, after a dizzying path that has already taken it past the Earth once and Venus twice.

The MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) spacecraft will make its very first flyby of the planet on January 14th at 2:04 EST. It will pass within 200 kilometers (124 miles) of the surface. During the flyby it will be taking images and scientific measurements of the planet’s features.

The data it will be taking this time around will complement the measurements it will make when finally in orbit. MESSENGER will map the composition of Mercury’s surface, capture images at a resolution of hundreds of meters, and measure the structure of the planet’s magnetosphere and magnetic and gravitational fields.

Monday’s flyby will be the first time a spacecraft has visited Mercury in 33 years, since Mariner 10 did a series of flybys in the mid-1970s. During that mission, the spacecraft only imaged one hemisphere of the planet. MESSENGER will complete the picture, so to speak, by taking close-up images for the very first time of the other hemisphere.

The flyby will allow the spacecraft to map several features of Mercury that it will not be able to measure when in orbit, such as the magnetotail – the drawn out tail of the planet’s magnetosphere as it travels through space. It will also take over 1,200 images of the planet.

MESSENGER was launched in August of 2004, and has been making its way to Mercury by a number of different flybys of the Earth and Venus. The journey, though, is far from over. The spacecraft will make two more flybys of Mercury in October 2008 and September 2009, finally settling into orbit of the planet in March 2011.

It will then start a yearlong comprehensive study with its seven scientific instruments. When the journey is over, it will have traveled 4.9 billion miles (7.9 billion kilometers).

For more information and photos of the flyby, visit the official MESSENGER website.

Source: Johns Hopkins University Applied Physics Laboratory Press Release