Bright Peaks, Dark Shadows

MESSENGER image of Mercury's Amaral crater

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The 68-mile (109-km) -wide Amaral crater on Mercury reveals its brightly-tipped central peaks in this image, acquired by NASA’s MESSENGER spacecraft on Feb. 4, 2012. Long shadows are cast by the crater’s peaks and rugged rim (north is to the left.)

The image was acquired as a high-resolution targeted observation with MESSENGER’s Narrow-Angle Camera (NAC) on its Mercury Dual Imaging System (MDIS).

Amaral’s bright peaks were first spotted during MESSENGER’s first flyby of Mercury in Jan. 2008. With a smooth floor, visible ejecta and small secondary craters, Amaral appeared noticeably younger than the heavily cratered surface around it.

Amaral's "blue" peaks seen in a color-enhanced global image acquired Jan. 14, 2008.

Its central peaks also attracted astronomers’ interest, as they were seen to possess a striking blue hue in color-enhanced images that likely indicates rocks with different composition from the surrounding surface.

Amaral’s peaks resemble those of the slightly larger crater Eminescu, which is now known to contain recently-discovered features called hollows. It’s not yet known if Amaral also contains hollows, but it’s suspected that they may be present on the tips of the peaks.

The crater is named after Brazilian artist Tarsila do Amaral. She lived from 1886 to 1973 and is considered to be one of the leading Latin American modernist painters.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

Kuiper’s Color Close-Up

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The pale-orange coloration around the 39-mile (62-km) -wide Kuiper crater on Mercury is evident in this image, a color composition made from targeted images acquired by NASA’s MESSENGER spacecraft on September 2, 2011.

The color may be due to compositional differences in the material that was ejected during the impact that formed the crater.

Kuiper crater is named after Gerard Kuiper, a Dutch-American astronomer who was a member of the Mariner 10 team. He is regarded by many as the father of modern planetary science.

“Kuiper studied the planets… at a time when they were scarcely of interest to other astronomers. But with new telescopes and instrumentation, he showed that there were great things to discover, which is as true today as it was then.”

– Dr. Bill McKinnon, Professor of Planetary Sciences at Washington University in St. Louis

Airless worlds like Mercury are constantly bombarded with micrometeoroids and charged solar particles in an effect known as “space weathering”. Craters with bright rays — like Kuiper — are thought to be relatively young because they have had less exposure to space weathering than craters without such rays.

See the original image release on the MESSENGER site here.

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

More “Hollowed Ground” on Mercury

MESSENGER captures image of curious "hollows" around a crater peak

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The latest featured image from NASA’s MESSENGER spacecraft, soon to complete its first year in orbit around Mercury, shows the central peak of the 78-mile (138-km) – wide crater Eminescu surrounded by more of those brightly-colored surface features dubbed “hollows”. Actually tinted a light blue color, hollows may be signs of an erosion process unique to Mercury because of its composition and close proximity to the Sun.

First noted in September of last year, hollows have now been identified in many areas across Mercury. They showed up in previous images as only bright spots, but once MESSENGER established orbit in March of 2011 and began high-resolution imaging of Mercury’s surface it became clear that these features were something totally new.

The lack of craters within hollows seems to indicate that they are relatively young features. In fact, they may be part of a process that continues even now.

“Analysis of the images and estimates of the rate at which the hollows may be growing led to the conclusion that they could be actively forming today,” said David Blewett of the Johns Hopkins University Applied Physics Laboratory (APL).

One hypothesis is that the hollows are formed by the sublimation of subsurface material exposed during the creation of craters, around which they are most commonly seen. Being so close to the Sun (29 million miles/46 million km at closest) and lacking a protective atmosphere like Earth’s, Mercury is constantly being scoured by the powerful solar wind. This relentless stream of charged particles may literally be “sandblasting” exposed volatile materials off the planet’s surface!

The image above shows an area approximately 41 miles (66 km) across. It has been rotated to enhance perspective; see the original image and caption here.

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

2011: Top Stories from the Best Year Ever for NASA Planetary Science!

Dawn Orbiting Vesta. NASA's Dawn spacecraft achieved orbit at the giant asteroid Vesta in July 2011. The depiction of Vesta is based on images obtained by Dawn's framing cameras. Dawn is an international collaboration of the US, Germany and Italy. Credit: NASA/JPL-Caltech

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A year ago, 2011 was proclaimed as the “Year of the Solar System” by NASA’s Planetary Science division. And what a year of excitement it was indeed for the planetary science community, amateur astronomers and the general public alike !

NASA successfully delivered astounding results on all fronts – On the Story of How We Came to Be.

“2011 was definitely the best year ever for NASA Planetary Science!” said Jim Green in an exclusive interview with Universe Today. Green is the Director of Planetary Science for the Science Mission Directorate at NASA HQ. “The Search for Life is a significant priority for NASA.”

This past year was without doubt simply breathtaking in scope in terms of new missions, new discoveries and extraordinary technical achievements. The comprehensive list of celestial targets investigated in 2011 spanned virtually every type of object in our solar system – from the innermost planet to the outermost reaches nearly touching interplanetary space.

There was even a stunningly evocative picture showing “All of Humanity” – especially appropriate now in this Holiday season !

You and all of Humanity are here !
-- Earth & Moon Portrait by Juno from 6 Million miles away --
First Photo transmitted from Jupiter Bound Juno shows Earth (on the left) and the Moon (on the right). Taken on Aug. 26, 2011 when spacecraft was about 6 million miles (9.66 million kilometers) away from Earth. Credit: NASA/JPL-Caltech

Three brand new missions were launched and ongoing missions orbited a planet and an asteroid and flew past a comet.

“NASA has never had the pace of so many planetary launches in such a short time,” said Green.

And three missions here were awarded ‘Best of 2011’ for innovation !

Mars Science Laboratory (MSL), Dawn and MESSENGER named “Best of What’s New” in 2011 by Popular Science magazine. 3 NASA Planetary Science missions received the innovation award for 2011 from Popular Science magazine. Artist concept shows mosaic of MESSENGER, Mars Science Laboratory and Dawn missions. Credit: NASA/JPL-Caltech

Here’s the Top NASA Planetary Science Stories of 2011 – ‘The Year of the Solar System’ – in chronological order

1. Stardust-NExT Fly By of Comet Tempel 1

Starting from the first moments of 2011 at the dawn of Jan. 1, hopes were already running high for planetary scientists and engineers busily engaged in setting up a romantic celestial date in space between a volatile icy comet and an aging, thrusting probe on Valentine’s Day.

The comet chasing Stardust-Next spacecraft successfully zoomed past Comet Tempel 1 on Feb. 14 at 10.9 km/sec (24,000 MPH) after flying over 6 Billion kilometers (3.5 Billion mi).

6 Views of Comet Tempel 1 and Deep Impact crater during Stardust-NExT flyby on Feb. 14, 2011
Arrows show location of man-made crater created in 2005 by NASA’s prior Deep Impact comet mission and newly imaged as Stardust-NExT zoomed past comet in 2011. The images progress in time during closest approach to comet beginning at upper left and moving clockwise to lower left. Credit: NASA/JPL-Caltech/University of Maryland. Post process and annotations by Marco Di Lorenzo & Kenneth Kremer

The craft approached within 178 km (111mi) and snapped 72 astonishingly detailed high resolution science images over barely 8 minutes. It also fulfilled the teams highest hopes by photographing the human-made crater created on Tempel 1 in 2005 by a cosmic collision with a penetrator hurled by NASA’s Deep Impact spacecraft. The probe previously flew by Comet Wild 2 in 2004 and returned cometary coma particles to Earth in 2006

Tempel 1 is the first comet to be visited by two spaceships from Earth and provided the first-ever opportunity to compare observations on two successive passages around the Sun.

Don Brownlee, the original Principal Investigator, summarized the results for Universe Today; “A great bonus of the mission was the ability to flyby two comets and take images and measurements. The wonderfully successful flyby of Comet Tempel 1 was a great cap to the 12 year mission and provided a great deal of new information to study the diversity among comets.”

“The new images of Tempel showed features that form a link between seemingly disparate surface features of the 4 comets imaged by spacecraft. Combining data on the same comet from the Deep Impact and Stardust missions has provided important new insights in to how comet surfaces evolve over time and how they release gas and dust into space”.

2. MESSENGER at Mercury

On March 18, the Mercury Surface, Space Environment, Geochemistry, and Ranging, or MESSENGER, spacecraft became the first spacecraft inserted into orbit around Mercury, the innermost planet.

So far MESSENGER has completed 1 solar day – 176 Earth days- circling above Mercury. The probe has collected a treasure trove of new data from the seven instruments onboard yielding a scientific bonanza; these include global imagery of most of the surface, measurements of the planet’s surface chemical composition, topographic evidence for significant amounts of water ice, magnetic field and interactions with the solar wind.

“MESSENGER discovered that Mercury has an enormous core, larger than Earth’s. We are trying to understand why that is and why Mercury’s density is similar to Earth’s,” Jim Green explained to Universe Today.

The First Solar Day
After its first Mercury solar day (176 Earth days) in orbit, MESSENGER has nearly completed two of its main global imaging campaigns: a monochrome map at 250 m/pixel and an eight-color, 1-km/pixel color map. Small gaps will be filled in during the next solar day. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

“The primary mission lasts 2 solar days, equivalent to 4 Mercury years.”

“NASA has granted a 1 year mission extension, for a total of 8 Mercury years. This will allow the team to understand the environment at Mercury during Solar Maximum for the first time. All prior spacecraft observations were closer to solar minimum,” said Green.

MESSENGER was launched in 2004 and the goal is to produce the first global scientific observations of Mercury and piece together the puzzle of how Mercury fits in with the origin and evolution of our solar system.

NASA’s Mariner 10 was the only previous robotic probe to explore Mercury, during three flyby’s back in the mid-1970’s early in the space age.

3. Dawn Asteroid Orbiter

The Dawn spacecraft achieved orbit around the giant asteroid Vesta in July 2011 after a four year interplanetary cruise and began transmitting the history making first ever close-up observations of the mysteriously diverse and alien world that is nothing short of a ‘Space Spectacular’.

“We do not have a good analog to Vesta anywhere else in the Solar System,” Chris Russell said to Universe Today. Russell, from UCLA, is the scientific Principal Investigator for Dawn.

Before Dawn, Vesta was just another fuzzy blob in the most powerful telescopes. Dawn has completely unveiled Vesta as a remarkably dichotomous, heavily battered and pockmarked world that’s littered with thousands of craters, mountains and landslides and ringed by mystifying grooves and troughs. It will unlock details about the elemental abundances, chemical composition and interior structure of this marvelously intriguing body.

Cataclysmic collisions eons ago excavated Vesta so it lacks a south pole. Dawn discovered that what unexpectedly remains is an enormous mountain some 16 miles (25 kilometers) high, twice the height of Mt. Everest.

Dawn is now about midway through its 1 year mission at Vesta which ends in July 2012 with a departure for Ceres, the largest asteroid. So far the framing cameras have snapped more than 10,000 never-before-seen images.

“What can be more exciting than to explore an alien world that until recently was virtually unknown!. ” Dr. Marc Rayman said to Universe Today. Rayman is Dawn’s Chief Engineer from NASA’s Jet Propulsion Lab (JPL) in Pasadena, Calif.

“Dawn is NASA at its best: ambitious, exciting, innovative, and productive.”

4. Juno Jupiter Orbiter

The solar powered Juno spacecraft was launched on Aug. 5 at Cape Canaveral Air Force Station in Florida, to embark on a five year, 2.8 billion kilometer (1.7 Billion mi) trek to Jupiter, our solar system’s largest planet. It was the first of three NASA planetary science liftoffs scheduled in 2011.

Juno Jupiter Orbiter soars skyward to Jupiter on Aug. 5, 2011 from Cape Canaveral Air Force Station, Florida. Credit: Ken Kremer

Juno’s goal is to map to the depths of the planets interior and elucidate the ingredients of Jupiter’s genesis hidden deep inside. These measurements will help answer how Jupiter’s birth and evolution applies to the formation of the other eight planets.

The 4 ton spacecraft will arrive at the gas giant in July 2016 and fire its braking rockets to go into a polar orbit and circle the planet 33 times over about one year.

The suite of nine instruments will scan the gas giant to find out more about the planets origins, interior structure and atmosphere, measure the amount of water and ammonia, observe the aurora, map the intense magnetic field and search for the existence of a solid planetary core.

“Jupiter is the Rosetta Stone of our solar system,” said Scott Bolton, Juno’s principal investigator from the Southwest Research Institute in San Antonio. “It is by far the oldest planet, contains more material than all the other planets, asteroids and comets combined and carries deep inside it the story of not only the solar system but of us. Juno is going there as our emissary — to interpret what Jupiter has to say.”

5. Opportunity reaches Endeavour Crater on Mars

The long lived Opportunity rover finally arrived at the rim of the vast 14 mile (22 kilometer) wide Endeavour Crater in mid-August 2011 following an epic three year trek across treacherous dune fields – a feat once thought unimaginable. All told, Opportunity has driven more than 34 km ( 21 mi) since landing on the Red Planet way back in 2004 for a mere 90 sol mission.

Endeavour Crater Panorama from Opportunity Mars Rover in August 2011
Opportunity arrived at the rim of Endeavour on Sol 2681, August 9, 2011 after a three year trek. The robot photographed segments of the huge craters eroded rim in this panoramic vista. Endeavour Crater is 14 miles (22 kilometers) in diameter. Mosaic Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Kenneth Kremer

In November, the rover discovered the most scientifically compelling evidence yet for the flow of liquid water on ancient Mars in the form of a water related mineral vein at a spot dubbed “Homestake” along an eroded ridge of Endeavour’s rim.

Read my story about the Homestake discovery here, along with our panoramic mosaic showing the location – created by Ken Kremer and Marco Di Lorenzo and published by Astronomy Picture of the Day (APOD) on 12 Dec. 2011.

Watch for my upcoming story detailing Opportunity’s accomplishments in 2011.

6. GRAIL Moon Mappers

The Gravity Recovery and Interior Laboratory, or GRAIL mission is comprised of twin spacecraft tasked to map the moon’s gravity and study the structure of the lunar interior from crust to core.

Twin GRAIL Probes GO for Lunar Orbit Insertion on New Year’s Eve and New Year’s Day
GRAIL spacecraft will map the moon's gravity field and interior composition. Credit: NASA/JPL-Caltech

The dynamic duo lifted off from Cape Canaveral on September 10, 2011 atop the last Delta II rocket that will likely soar to space from Florida. After a three month voyage of more than 2.5 million miles (4 million kilometers) since blastoff, the two mirror image GRAIL spacecraft dubbed Grail-A and GRAIL-B are sailing on a trajectory placing them on a course over the Moon’s south pole on New Year’s weekend.

Each spacecraft will fire the braking rockets for about 40 minutes for insertion into Lunar Orbit about 25 hours apart on New Year’s Eve and New Year’s Day.

Engineers will then gradually lower the satellites to a near-polar near-circular orbital altitude of about 34 miles (55 kilometers).

The spacecraft will fly in tandem and the 82 day science phase will begin in March 2012.

“GRAIL is a Journey to the Center of the Moon”, says Maria Zuber, GRAIL principal investigator from the Massachusetts Institute of Technology (MIT). “GRAIL will rewrite the book on the formation of the moon and the beginning of us.”

“By globally mapping the moon’s gravity field to high precision scientists can deduce information about the interior structure, density and composition of the lunar interior. We’ll evaluate whether there even is a solid or liquid core or a mixture and advance the understanding of the thermal evolution of the moon and the solar system,” explained co-investigator Sami Asmar to Universe Today. Asmar is from NASA’s Jet Propulsion Laboratory (JPL)

7. Curiosity Mars Rover

The Curiosity Mars Science Lab (MSL) rover soared skywards on Nov. 26, the last of 2011’s three planetary science missions. Curiosity is the newest, largest and most technologically sophisticated robotic surveyor that NASA has ever assembled.

“MSL packs the most bang for the buck yet sent to Mars.” John Grotzinger, the Mars Science Laboratory Project Scientist of the California Institute of Technology, told Universe Today.

The three meter long robot is the first astrobiology mission since the Viking landers in the 1970’s and specifically tasked to hunt for the ‘Ingredients of Life’ on Mars – the most Earth-like planet in our Solar System.


Video caption: Action packed animation depicts sequences of Curiosity departing Earth, the nail biting terror of the never before used entry, descent and landing on the Martian surface and then looking for signs of life at Gale Crater during her minimum two year expedition across hitherto unseen and unexplored Martian landscapes, mountains and craters. Credit: NASA

Curiosity will gather and analyze samples of Martian dirt in pursuit of the tell-tale signatures of life in the form of organic molecules – the carbon based building blocks of life as we know it.

NASA is targeting Curiosity to a pinpoint touch down inside the 154 km (96 mile) wide Gale Crater on Aug. 6, 2012. The crater exhibits exposures of phyllosilicates and other minerals that may have preserved evidence of ancient or extant Martian life and is dominated by a towering 3 mile (5 km) high mountain.

“10 science instruments are all aimed at a mountain whose stratigraphic layering records the major breakpoints in the history of Mars’ environments over likely hundreds of millions of years, including those that may have been habitable for life,” Grotzinger told me.

Titan Upfront
The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft. Credit: NASA/JPL-Caltech/Space Science Institute
Curiosity Mars Science Laboratory Rover and Ken Kremer - inside the Cleanroom at the Kennedy Space Center. Last View of Curiosity just prior to folding and encapsulation for launch. Credit: Ken Kremer

This past year Ken was incredibly fortunate to witness the ongoing efforts of many of these magnificent endeavors.

Our Own Private Hell: Unlocking Mercury’s Enigmatic Past

Craters and secondary craters create a hellish scene in this MESSENGER image of Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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Editor’s note: Bruce Dorminey, science journalist and author of “Distant Wanderers: The Search for Planets Beyond the Solar System,” interviews NASA’s MESSENGER mission Project Scientist Ralph McNutt about what we are learning about Mercury.

Thirty-five years after NASA’s Mariner 10 interplanetary probe flew by and imaged less than half of tiny Mercury’s surface, NASA’s MESSENGER spacecraft now orbits our Solar System’s enigmatic and poorly understood innermost planet. After a six-and-a-half-year journey — which included three flybys of Mercury — MESSENGER is now the first spacecraft to take up long-term residence around this hard-to-reach and hellish planet.

Crater-scarred Mercury lies at an average distance of only 58 million kms from the Sun, so searingly close that its angular separation (or elongation) from our own star is never more than 28 degrees.  This all makes it extremely difficult to study from Earth.

Thus, planetary scientists are thrilled to finally be analyzing new in situ data from the MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft.

To get some perspective on the findings and Mercury itself, we turned to the  MESSENGER Project Scientist Ralph McNutt at Johns Hopkins University’s Applied Physics Lab.


Dorminey — Is the MESSENGER data already shaking up Mercury paradigms?


McNutt — Yes – the biggest issue has been the volatile content which is likely going to lead to an interesting, but productive debate, about implications for planetary origins in the inner solar system.

“Volatile” elements are those with relatively low melting and boiling points. “Refractory” elements have relatively high boiling and melting points. If Mercury has a large core due to the surface being “boiled off” by a hot solar wind or hotter Sun in the early days of the solar system, or by a giant impact, then it is more difficult – but perhaps not impossible – for the volatile to refractory ratio, as exemplified by the potassium to thorium ratio (K/Th), to be as high on Mercury as at Earth, Mars, and Venus.  And yet that is what the data are saying.

Dorminey — What could explain Mercury’s magnetic field being offset north of the planet’s center by 20 percent of its radius?  Was this offset due to a giant impactor?

Ralph McNutt. Credit: NASA

McNutt — My guess would be that the offset is not due to a giant impactor.  But we still do not have a good explanation.

Dorminey — But does the in situ measurement of this magnetic field also confirm that Mercury still has an active magnetic dynamo?

McNutt — There seems to be no way that [Mercury] can escape having a dynamo, so that already makes for implications about Mercury’s cooling history and the chemical mixture [needed] for the dynamo action. There needs to be mostly iron, but something else must be mixed in to help lower the freezing point, otherwise the dynamo should have frozen out some time back.

“Dynamo” in either a planetary or commercial context refers to the generation of electricity by movement of a conductor with respect to a preexisting magnetic filed. Such a movement produces an electrical current, which, in turn, produces a magnetic field.

In a planet, the conductor is a liquid with motion derived from the rotational energy of the planet.  But a full theoretical description of how planetary dynamos work is still lacking and is the subject of ongoing research.

Dorminey — A popular formation theory, which would explain its anomalously large iron core, is that early Mercury was stripped of its outer layers following a giant impact.  Do you adhere to this idea?

McNutt — Nominally, a high volatile content – expressed via a high potassium to thorium ratio (K/Th), which we have measured with the MESSENGER gamma-ray spectrometer, would rule against such a massive impact. The thinking has been that the volatile content would not re-accrete and so one would be left with a low global average such as is measured for the Moon. We will see – I do not think the verdict is in yet on this one.

A global mosaic of Mercury from MESSENGER. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Dorminey — What is the significance of and where did it get its surface sulfur and potassium?

McNutt — Sulfur and potassium were both elements in the initial solar nebula. The real question is what led to their placement and relative concentrations on the surface of Mercury.

Dorminey — What’s the significance of the MESSENGER-imaged volcanic vents?  Is Mercury still tectonically active?

McNutt — The volcanic vents tells us that volcanism was a significant part of the geologic history of the planet.  The planet has cooled a lot since there was a lot of activity and continues to cool. The level of activity is likely low at best – but if we see an active [volcanic] vent, we will definitely let the world know.


Dorminey — We know that Mercury has an exosphere, but could Mercury ever have had anything approaching an Earthlike atmosphere?

McNutt — Any sort of a stable Earth-like atmosphere is not in the cards. Mercury is too small with too small a gravity field to hold on to anything for a long time. If there was sufficiently rapid outgassing , then one could have built up an atmosphere of something that might have Earth-like pressures, but certainly no oxygen, and not for long given the temperature.


Dorminey — What is still the most puzzling to you about Mercury?

McNutt — Right now, the biggest puzzle is how to put together the magnetic field configuration (with the offset), with a dynamo, and the topography and gravity data all in a self-consistent description of the planet. There will be some more papers coming out on these topics in the near future.


Dorminey — If money were no object, what would be the ultimate science exploration strategy for Mercury?  Are there any plans in the works for a lander?

McNutt — To really understand the solar system, we need to put together a coherent chronology of formation and early thermal evolution of the planets and other solar system objects.  To do that “right” one needs well-characterized samples returned from the surface or drilled from the near-surface, in pristine environments and delivered to labs on Earth.  Sample returns are hard – but not as hard as placing such equipment in situ. Following the next level of intense study by BepiColombo (the ESA orbital mission now in development), the next step is a lander. There are no plans for such a mission at present.  An interesting question is which is harder: a sample return mission from Mercury or from Venus.

Dorminey — With dayside temperatures of 630 kelvin and nightside temperatures of 95 kelvin, could Mercury have ever been a candidate for liquid water or oceans?

McNutt — No.

Dorminey — Could Mercury have ever had microbial life?

McNutt — Before it was known that Mercury rotated, there was some speculation that there might be a zone of perpetual twilight between the Sun-facing hot side and the Sun-shadowed cold side a “twilight zone” where something [like microbial life] might be possible.  In actuality, the region between hot and cold would have been fairly abrupt (depending on the thermal conductivity of the rocks). As Mercury does rotate, no such region exists.

The young rays of Mena crater contrast brightly against the surrounding surface of Mercury. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Dorminey — What’s the ultimate significance of planetary science’s study of Mercury? Does it offer a template for what you expect in other solar systems, or does your gut tell you that it’s a total fluke?

McNutt — Knowing more about Mercury, and Venus and Mars tells us about the “terrestrial planets” as a whole and what was common – and special – about ours – and their origins. While the new exoplanet discoveries are extremely interesting, we will not get as close to those planets as we can get to the ones in our own Solar System anytime soon. We have yet to be able to resolve other “Mercurys” in our exoplanet searches, so it is as likely as good a template as any.  In learned circles at one time in the not too distant past, the entire solar system was considered to be a total fluke.

NASA Planetary Science Trio Honored as ‘Best of What’s New’ in 2011- Curiosity/Dawn/MESSENGER

Popular Science magazine names NASA’s Mars Science Laboratory, Dawn and MESSENGER missions as ‘Best of What’s New’ in innovation in 2011. Artist concept shows mosaic of MESSENGER, Mars Science Laboratory and Dawn missions. Credit: NASA/JPL-Caltech

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A trio of NASA’s Planetary Science mission’s – Mars Science Laboratory (MSL), Dawn and MESSENGER – has been honored by Popular Science magazine and selected as ‘Best of What’s New’ in innovation in 2011 in the aviation and space category.

The Curiosity Mars Science Laboratory was just launched to the Red Planet on Saturday, Nov. 26 and will search for signs of life while traversing around layered terrain at Gale Crater. Dawn just arrived in orbit around Asteroid Vesta in July 2011. MESSENGER achieved orbit around Planet Mercury in March 2011.

Several of the top mission scientists and engineers provided exclusive comments about the Popular Science recognitions to Universe Today – below.

“Of course we are all very pleased by this selection,” Prof. Chris Russell, Dawn Principal Investigator, of UCLA, told Universe Today.


Dawn is the first mission ever to specifically investigate the main Asteroid Belt between Mars and Jupiter and will orbit both Vesta and Ceres – a feat enabled solely thanks to the revolutionary ion propulsion system.

“At the same time I must admit we are also not humble about it. Dawn is truly an amazing mission. A low cost mission, using NASA’s advanced technology to enormous scientific advantage. It is really, really a great mission,” Russell told me.

Vesta is the second most massive asteroid and Dawn’s discoveries of a surprisingly dichotomous and battered world has vastly exceeded the team’s expectations.

Asteroid Vesta from Dawn - Exquisite Clarity from a formerly Fuzzy Blob
NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. It was taken from a distance of about 3,200 miles (5,200 kilometers). Before Dawn, Vesta was just a fuzzy blob in the most powerful telescopes. Dawn entered orbit around Vesta on July 15, and will spend a year orbiting the body before firing up the ion propulsion system to break orbit and speed to Ceres, the largest Asteroid. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

“Dawn is NASA at its best: ambitious, exciting, innovative, and productive,” Dr. Marc Rayman, Dawn’s Chief Engineer from the Jet Propulsion Lab (JPL), Pasadena, Calif., told Universe Today.

“This interplanetary spaceship is exploring uncharted worlds. I’m delighted Popular Science recognizes what a marvelous undertaking this is.”

JPL manages both Dawn and Mars Science Laboratory for NASA’s Science Mission Directorate in Washington, D.C.

Dawn is an international science mission. The partners include the German Aerospace Center (DLR), the Max Planck Institute for Solar System Research, the Italian Space Agency and the Italian National Astrophysical Institute.

“Very cool!”, John Grotzinger, the Mars Science Laboratory Project Scientist of the California Institute of Technology, told Universe Today.

“MSL packs the most bang for the buck yet sent to Mars.”

Last View of Curiosity Mars Science Laboratory Rover - inside the Cleanroom at KSC.
Curiosity just before Encapsulation for 8 month long interplanetary Martian Journey and touchdown inside Gale Crater. Credit: Ken Kremer

Curiosity is using an unprecedented precision landing system to touch down inside the 154 km (96 miile) wide Gale Crater on Aug. 6, 2012. The crater exhibits exposures of phyllosilicates and other minerals that may have preserved evidence of ancient or extant Martian life and is dominated by a towering mountain.

“10 instruments all aimed at a mountain higher than any in the lower 48 states, whose stratigraphic layering records the major breakpoints in the history of Mars’ environments over likely hundreds of millions of years, including those that may have been habitable for life.”

“It’s like a trip down the Grand Canyon 150 years ago, with the same sense of adventure, but with a lot of high tech equipment,” Grotzinger told me.

MSL also has an international team of over 250 science investigators and instruments spread across the US, Europe and Russia.

Curiosity Mars Science Laboratory rover soars to Mars atop an Atlas V rocket on Nov. 26 at 10:02 a.m. EST from Cape Canaveral, Florida. Credit: Ken Kremer

MESSENGER is the first probe to orbit Mercury and the one year primary mission was recently extended by NASA.

Sean Solomon, of the Carnegie Institution of Washington, leads the MESSENGER mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft for NASA.

“Planetary has 3 missions there… Dawn, MESSENGER, and MSL,” Jim Green proudly said to Universe Today regarding the Popular Science magazine awards. Green is the director, Planetary Science Division, NASA Headquarters, Washington

“Three out of 10 [awards] is a tremendous recognition of the fact that each one of our planetary missions goes to a different environment and takes on new and unique measurements providing us new discoveries and constantly changes how we view nature, ourselves, and our place in the universe.”

The First Solar Day
After its first Mercury solar day (176 Earth days) in orbit, MESSENGER has nearly completed two of its main global imaging campaigns: a monochrome map at 250 m/pixel and an eight-color, 1-km/pixel color map. Apart from small gaps, which will be filled in during the next solar day, these global maps now provide uniform lighting conditions ideal for assessing the form of Mercury’s surface features as well as the color and compositional variations across the planet. The orthographic views seen here, centered at 75° E longitude, are each mosaics of thousands of individual images. At right, images taken through the wide-angle camera filters at 1000, 750, and 430 nm wavelength are displayed in red, green, and blue, respectively.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Read more about the Popular Science citations and awards here
.
Read continuing features about Curiosity, Dawn and MESSENGER by Ken Kremer starting here:

Curiosity Mars Rover Launch Gallery – Photos and Videos
Curiosity Majestically Blasts off on ‘Mars Trek’ to ascertain ‘Are We Alone?
Dawn Discovers Surprise 2nd Giant South Pole Impact Basin at Strikingly Dichotomous Vesta
Amazing New View of the Mt. Everest of Vesta
MESSENGER Unveiling Mercurys Hidden Secrets

Incredible ‘Sideways’ Look at Mercury’s Limb

A mosaic of nine oblique views from the MESSENGER spacecraft of Mercury's limb, looking towards the horizon. Click for larger, more amazing view. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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Wow — just wow! Here’s a unique, jaw-dropping, and beautiful look at Mercury from the MESSENGER spacecraft, in a mosaic created from nine images taken by the Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS). The camera took a “sideways” or oblique view of Mercury’s limb, looking towards the horizon, providing a distinctive look at the rough terrain, ridges, craters and scarps of the Van Eyck Formation region, adjacent to the Caloris basin. Combining the images for a larger view not only provides a “you are there” feel, but it provides the science team with new ways to study Mercury’s geology.

Make sure you click on the image for a larger, even more amazing view. You can compare this image with a “straight-down” look of the same region, below.

Correlation of features between the limb mosaic and an overhead view. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Looking at any landscape in from different angles has a major impact on how terrain location and feature orientation is perceived, the MESSENGER science team explained in a detailed description of how this image was made. While single images that focus on one feature are wonderful for in-depth explorations, combining images together in a mosaic studying can provide regional or even global perspective. These mosaics are particularly important for understanding the geological context of a particular feature and for exploring Mercury’s geologic history.

The Van Eyck region was formed by ejecta from the Caloris basin. Visible in the overhead view are “ghost craters” which are impact craters that were later buried by the voluminous volcanic lavas that form the plains in this part of Mercury. What appear as rough terrain and ridges in the oblique limb view show up as lineated, distinctive features from overhead. Both views provide clues to scientists about the processes or environment that the features formed.

The ejecta blanket of Caloris basin is to the lower left of the overhead-view.

The limb mosaic is just 9 of 75,000 images the NAC has taken and will continue to take during MESSENGER’s primary mission, which goes through March of 2012. These images were taken in June of 2011, and the mosaic was released today by the imaging team.

Source: MESSENGER

Hat tip: Stu Atkinson

“Extreme” Solar Wind Blasts Mercury’s Poles

Planet Mercury as seen from the MESSENGER spacecraft in 2008. Credit: NASA/JPL

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According to data from the The Fast Imaging Plasma Spectrometer (FIPS) onboard NASA’s MESSENGER spacecraft, the solar wind is “sandblasting” the surface of Mercury at its polar regions.

Based on findings from one of seven different papers from the MESSENGER mission to be published in the Sept. 30th edition of Science, sodium and oxygen particles are charged in a manner similar to Earth’s own Aurora Borealis.

How are the University of Michigan researchers able to detect and study this phenomenon?

Using the FISP, the scientists at the University of Michigan have taken measurements of Mercury’s exosphere and magnetosphere. The data collected has provided researchers with a better understanding of interactions between Mercury and our Sun. FIPS data has also confirmed theories regarding the composition and source of particles in Mercury’s space environment.

“We had previously observed neutral sodium from ground observations, but up close we’ve discovered that charged sodium particles are concentrated near Mercury’s polar regions where they are likely liberated by solar wind ion sputtering, effectively knocking sodium atoms off Mercury’s surface,” said FIPS project leader Thomas Zurbuchen (University of Michigan).

In a UM press release, Zurbuchen added, “We were able to observe the formation process of these ions, and it’s comparable to the manner by which auroras are generated in Earth’s atmosphere near polar regions.”

Given that Earth and Mercury are the only two magnetized planets in the inner solar system (Mars is believed to have had a magnetic field in its past), the solar wind is deflected around them. The solar wind has made recent news due to recent outbursts from the Sun causing visible aurorae, caused by the interaction of charged particles from the Sun and Earth’s relatively strong magnetosphere. While Mercury does have a magnetosphere, compared to Earth’s it is relatively weak. Given Mercury’s weak magnetosphere and close proximity to the Sun, the effects of the solar wind have a more profound effect.

The Fast Imaging Plasma Spectrometer on board MESSENGER has found that the solar wind is able to bear down on Mercury enough to blast particles from its surface into its wispy atmosphere.
Image Credit: Shannon Kohlitz, Media Academica, LLC

“Our results tell us is that Mercury’s weak magnetosphere provides very little protection of the planet from the solar wind,” Zurbuchen said.

Jim Raines, FIPS operations engineer (University of Michigan) added, “We’re trying to understand how the sun, the grand-daddy of all that is life, interacts with the planets. It is Earth’s magnetosphere that keeps our atmosphere from being stripped away. And that makes it vital to the existence of life on our planet.”

A high-resolution monochrome image has been combined with a lower-resolution enhanced-color image. The hollows appear in cyan, a result of their high reflectance and bluish color relative to other parts of the planet. The large pit in the center of the crater may be a volcanic vent, from which the orange material erupted. Credit: Courtesy of Science/AAAS

The MESSENGER team also released other results from the mission, including new evidence that flood volcanism has been widespread on Mercury, the first close-up views of Mercury’s “hollows,” and the first direct measurements of the chemical composition of Mercury’s surface.

MESSENGER, as well the the Mariner 10 flyby mission saw unusual features on the floors and central mountain peaks of some impact craters which were very bright and have a blue color relative to other areas of Mercury. This type of feature is not seen on the Moon, and were nicknamed “hollows.”

Now, with the latest MESSENGER data, hollows have been found over a wide range of latitudes and longitudes, suggesting that they are fairly common across Mercury. Many of the depressions have bright interiors and halos.

“To the surprise of the science team, it turns out that the bright areas are composed of small, shallow, irregularly shaped depressions that are often found in clusters,” says David Blewett, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and lead author of one of the Science reports. “The science team adopted the term ‘hollows’ for these features to distinguish them from other types of pits seen on Mercury.”

Blewett added the hollows detected so far have a fresh appearance and have not accumulated small impact craters, indicating that they are relatively young.

If you’d like to learn more about the MESSENGER mission, visit: http://www.nasa.gov/mission_pages/messenger/main/index.html , or http://messenger.jhuapl.edu/

Sources: MESSENGER News Release NASA

MESSENGER Unveiling Mercurys Hidden Secrets

Spectacular view of the Degas crater from MESSENGER in Mercury orbit. This high-resolution view of Degas crater was obtained as a targeted observation (90 m/pixel). Impact melt coats its floor, and as the melt cooled and shrank, it formed the cracks observed across the crater. For context, Mariner 10’s view of Degas is shown at left. Degas is 52 km in diameter and is centered at 37.1° N, 232.8° E. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

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NASA’s MESSENGER probe to Mercury, the scorched, innermost planet of our solar system, is sending back so much startling and revolutionary data and crystal clear images that the results are forcing scientists to toss out previously cherished theories and formulate new ones even as the results continues to pour in. And the mission has barely begun to explore Mercury’s inner secrets, exterior surface and atmospheric environment.

MESSENGER became the first spacecraft ever to orbit planet Mercury on March 18, 2011 and has just completed the first quarter of its planned one year long mission – that’s the equivalent of one Mercury year.

MESSENGER has collected a treasure trove of new data from the seven instruments onboard yielding a scientific bonanza; these include extensive global imagery, measurements of the planet’s surface chemical composition, topographic evidence for significant amounts of water ice, magnetic field and interactions with the solar wind, reported the science team at a press conference at NASA Headquarters.

Schematic illustration of the operation of MESSENGER's X-ray Spectrometer (XRS). When X-rays emitted from the Sun’s corona strike the planet, they can induce X-ray fluorescence from atoms at the surface. Detection of these fluorescent X-rays by the XRS allows determination of the surface chemical composition. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

“We are delighted to share the findings of the first 25% of our year long mission,” said MESSENGER principal investigator Sean Solomon of the Carnegie Institution of Washington at a press briefing for reporters. “We receive new data back almost every day.”

“MESSENGER has snapped over 20,000 images to date,” said Solomon, at up to 10 meters per pixel. The probe has also taken over two million laser-ranging topographic observations, discovered vast volcanic plains, measured the abundances of many key elements and confirmed that bursts of energetic particles in Mercury’s magnetosphere result from the interaction of the planets magnetic field with the solar wind.

“We are assembling a global overview of the nature and workings of Mercury for the first time.”

“We had many ideas about Mercury that were incomplete or ill-formed, from earlier flyby data,” explained Solomon. “Many of our older theories are being cast aside into the dust bin as new observations from new orbital data lead to new insights. Our primary mission has another three Mercury years to run, and we can expect more surprises as our solar system’s innermost planet reveals its long-held secrets.”

Magnetic field lines differ at Mercury's north and south poles As a result of the north-south asymmetry in Mercury's internal magnetic field, the geometry of magnetic field lines is different in Mercury's north and south polar regions. In particular, the magnetic "polar cap" where field lines are open to the interplanetary medium is much larger near the south pole. This geometry implies that the south polar region is much more exposed than in the north to charged particles heated and accelerated by solar wind–magnetosphere interactions. The impact of those charged particles onto Mercury's surface contributes both to the generation of the planet's tenuous atmosphere and to the "space weathering" of surface materials, both of which should have a north-south asymmetry given the different magnetic field configurations at the two poles. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

NASA’s Mariner 10 was the only previous robotic probe to explore Mercury, during three flyby’s back in the mid-1970’s early in the space age.

MESSENGER was launched in 2004 and the mission goal is to produce the first global scientific observations of Mercury and piece together the puzzle of how Mercury fits in with the origin and evolution of our solar system.

There was very little prior imaging coverage of Mercury’s northern polar region.

“We’ve now filled in many of the gaps,” said Messenger scientist Brett Denevi of Johns Hopkins University’s Applied Physics Laboratory (APL). “We now see large smooth plains that are thought to be volcanic in origin.”

“Now we’re seeing for the first time their full extent, which is around 4 million square kilometers (1.54 million square miles). That’s about half the size of the continental United States.”

MESSENGER is currently filling in coverage of Mercury’s north polar region, which was seen only partially during the Mariner 10 and MESSENGER flybys. Flyby images indicated that smooth plains were likely important in Mercury’s northernmost regions. MESSENGER's orbital images show that the plains are among the largest expanses of volcanic deposits on Mercury, with thicknesses of several kilometers in many places. The estimated extent of these plains is outlined in yellow. This mosaic is a combination of flyby and orbital coverage in a polar stereographic projection showing latitudes from 50° to 90° N. The longitude at the 6 o'clock position is 0°. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

“We see all kinds of evidence for volcanism and tectonic deformation of the plains from orbit where we can look straight down,” added Denevi. “In the new images we see ghost craters from pre-existing impact craters that were later covered over by lava.’

Color images of the whole planet – with a resolution of about 1 kilometer per pixel – tell the researchers about the chemical composition and rock types on Mercury’s surface.

“We don’t know the composition yet.”

“We are very excited to study these huge volcanic deposits near the north pole with the implications for the evolution of Mercury’s crust and how it formed,” said Denevi.

“Targeted new high resolution imaging is helping us see landforms unlike anything we’ve seen before on Mercury or the moon.”

MESSENGER’s orbital images have been overlaid on an image from the second flyby shown in Image 1.2a. Even for previously imaged portions of the surface, orbital observations reveal a new level of detail. This region is part of the extensive northern plains, and evidence for a volcanic origin can now be seen. Several examples of “ghost” craters, preexisting craters that were buried by the emplacement of the plains, are seen near the center of the mosaic. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Determining whether Mercury harbors caches of polar water ice is another one of the many questions the MESSENGER science team hopes to answer.

Two decades ago, Earth-based radar images showed deposits thought to consist of water ice near Mercury’s north and south poles. Researchers postulated a theory that these icy deposits are preserved on the cold, permanently shadowed floors of high-latitude impact craters, similar to those on Earth’s moon.

Early results from topographic measurements are promising.

“The very first scientific test of that hypothesis using Messenger data from orbit has passed with flying colors.”

“The area of possible polar water ice is quite a bit larger than on the moon,” said Solomon. “Its probably meters or more in depth based on radar measurements.”

“And we may have the irony that the planet closest to the sun may have more water ice at its poles than even our own moon.”

“Stay tuned. As this mission evolves, we will be relying on the geochemical and remote sensing instruments which take time to collect observations. The neutron and gamma ray spectrometers have the ability to tell us the identity of these icy materials,” said Solomon.

The same scene as that in Image 1.3a is shown after the application of a statistical method that highlights differences among the eight color filters, making variations in color and composition easier to discern. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This topographic contour map was constructed from the several MLA profiles (lines of white circles) that pass through and near the crater circled in Image 3.4. The color scale at right is in km, and north is at the 4 o’clock position. Calculations show that the topography of the crater is consistent with the prediction that the southernmost portion of the crater floor is in permanent shadow. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
A cross-section of Mercury’s magnetosphere (in the noon-midnight plane, i.e., the plane containing the planet-Sun line and Mercury’s spin axis) provides context for the energetic electron events observed to date with the MESSENGER XRS and GRS high-purity germanium (HpGe) detectors. The Sun is toward the right; dark yellow lines indicate representative magnetic field lines. Blue and green lines trace the regions along MESSENGER's orbit from April 2 to April 10 during which energetic electrons were detected and MESSENGER's orbit was within ± 5° of the noon-midnight plane. The presence of events on the dayside, their lack in the southern hemisphere, and their frequency of occurrence at middle northern latitudes over all longitudes point to a more complex picture of magnetospheric activity than found at Earth. Credit: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Messages from Mercury

MESSENGER's view from Mercury's south pole

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It’s been just over two months since the MESSENGER spacecraft successfully entered orbit around Mercury, back on March 18, and it’s been enthusiastically returning image after image of our solar system’s innermost planet at a unprecedented rate. Which, of course, is just fine with us!

The image above shows Mercury’s southern hemisphere and the bright rays of the 50-km-wide crater Han Kan. It was acquired on May 17, 2011.

Below are more recent images from MESSENGER… some of which show regions and features that have never previously been mapped – or even named!

Unnamed double peak-ring basin. Acquired May 13.
Detail of the mountains that make up the rim of Caloris Basin. Acquired May 5.
Narrow-angle camera view of the 100-km-wide Atget crater. Acquired May 10.
Color map of Mercury's surface. The bright crater is Snorri (21km wide). Acquired April 15.

Click on the images to see more detail on the MESSENGER mission site.

MESSENGER’s orbit about Mercury is highly elliptical, taking it 200 kilometers (124 miles) above its northern surface at the closest pass and 15,193 kilometers (9,420 miles) away from the south pole at furthest. Check out this video showing an animation of how a typical MESSENGER orbit would be executed.

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

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft’s seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System’s innermost planet. During the one-year primary mission, MDIS is scheduled to acquire more than 75,000 images in support of MESSENGER’s science goals.