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Old 12-09-2008, 08:23 AM   #31
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MESSENGER Mission News
December 8, 2008
http://messenger.jhuapl.edu/


MESSENGER Completes Two-Part Maneuver; Poised for Third Mercury Encounter

MESSENGER completed the second part of a two-part deep-space maneuver today, providing the remaining 10% velocity change needed to place the probe on course to fly by Mercury for the third time in September 2009.

Unlike most maneuvers, this one was conducted in a so-called “open loop,” explained MESSENGER Project Manager Peter Bedini. “In closed-loop maneuvers, the accelerometers are used to trim the burn, and thrusters are employed as needed to adjust the direction as perceived by the accelerometers,” said Bedini, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. “To test the unlikely scenario that we will not have accelerometer data for the huge Mercury orbit insertion, we did this second part without using those data as feedback.”

The first part of the maneuver, which occurred on December 4, increased the probe’s speed relative to the Sun by 219 meters per second (489 miles per hour) to about 30.994 kilometers per second (69,333 miles per hour). Today’s maneuver, which began at 3:30 p.m. EST, increased MESSENGER’s speed by an additional 24.7 per second, for a total velocity change of 247 meters per second. Mission controllers at APL verified the start of the maneuver about 13 minutes, 18 seconds later, when the first signals indicating spacecraft thruster activity reached NASA’s Deep Space Network tracking station in Canberra, Australia.

“We are now on target for the third Mercury flyby next September,” Bedini said. “The fifth deep-space maneuver two months later will position MESSENGER for Mercury orbit insertion in March 2011,” enabling it to become the first spacecraft to orbit the innermost planet.



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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Old 12-24-2008, 09:04 AM   #32
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MESSENGER Mission News
December 23, 2008
http://messenger.jhuapl.edu/




MESSENGER Approaches Three Billion Miles, Enters Fourth Solar Conjunction

On December 26, the MESSENGER spacecraft will have traveled three billion miles since its launch, marking somewhat more than 60 percent of the probe’s journey toward its destination to be inserted into orbit about Mercury.

“That MESSENGER’s odometer reading has reached another major milestone reminds us of the long and complex route that our spacecraft must follow,” offers Principal Investigator Sean Solomon, of the Carnegie Institution of Washington “The year now ending has seen the first two spacecraft flybys of the innermost planet in more than three decades, encounters that have yielded a rich lode of new observations. The journey is far from over, but MESSENGER has a skilled team to guide it the rest of the way.”

Mercury orbits deep within the Sun’s gravity well. So, even though the planet can be as close as 82 million kilometers (51 million miles) from Earth, getting the probe into orbit around Mercury depends on an innovative trajectory using the gravity of Earth, Venus, and Mercury itself to slow and shape the probe's descent into the inner solar system. On its 4.9 billion-mile journey to becoming the first spacecraft to orbit the planet Mercury, MESSENGER has flown by Earth once, Venus twice, and Mercury twice. Still to come is one more flyby of Mercury in late September 2009.

Today the spacecraft entered its fourth superior solar conjunction of the mission, placing it on the opposite side of the Sun from Earth. (To see where MESSENGER is now, visit http://messenger.jhuapl.edu/whereis/index.php.) The Sun-Earth-probe angle will be between 2° and 3° until January 6, 2009, so during the next two weeks there will be no communication with the spacecraft.

To support the conjunction period, the MESSENGER team performed several activities to prepare the spacecraft and keep it safe, explains MESSENGER Mission Operations Manager Andy Calloway. Examples include extension of the onboard command detection timer and inclusion of attitude alternations to avoid an autonomous propulsive burn to unload spacecraft angular momentum. In addition, all instruments have been turned off except for the Gamma-Ray Spectrometer sensor, which will remain in a maintenance mode to control closely the temperature of its cryogenic cooler.

“The team will gather for a spacecraft health assessment on the first contact after the conjunction, and then the payload will be powered on again, timers will be restored, and nominal operations will resume,” says Calloway, of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “The next superior solar conjunction lasts only five days – from June 6 to June 10 – and will therefore not require such extensive preparations.” The next long conjunction spans about two weeks beginning on November 2, 2009.

The MESSENGER spacecraft is a little more than two years from reaching its final destination, but the mission Science Team has been collecting data and sharing it with the larger scientific community. Those plans and results are available online at http://messenger.jhuapl.edu/soc/index.html.



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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Old 02-09-2009, 03:02 PM   #33
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MESSENGER Continues Hunt for Ever-Elusive Vulcanoids

MESSENGER reaches its orbital perihelion today and passes within 0.31 astronomical units (AU) of the Sun (one AU is nearly 150 million kilometers or 93 million miles). The mission’s imaging team is taking advantage of the probe’s proximity to the fiery sphere to continue their search for vulcanoids – small, rocky asteroids that have been postulated to circle the Sun in stable orbits inside the orbit of Mercury.

Vulcanoids are named after Vulcan, a planet once proposed to explain unusual motions in Mercury’s orbit. Scientists have long suspected that these small, faint “space rocks” exist. There is a gravitationally stable region between the orbit of Mercury and the Sun, which means that any objects that originally formed there could have remained for billions of years and might still be there today. All other such regions in the solar system are occupied by some type of debris (e.g., Trojan asteroids at stable points along the orbits of Jupiter and Neptune and Kuiper Belt objects near and beyond the orbit of Pluto).

The so-called vulcanoid region between the orbit of Mercury and the Sun is the main gravitationally stable region that is not known to be occupied. The region is, however, the most difficult to observe. Any vulcanoids would be difficult to detect from Earth because of the strong glare of the Sun. Previous vulcanoid searches have revealed no bodies larger than 60 kilometers in diameter. But MESSENGER’s travels in near-Mercury space enable a search for vulcanoids from a vantage never before attempted, says MESSENGER Science Team Member Clark Chapman, who is spearheading the team’s search along with his associate, William Merline.

“With MESSENGER, we can search for vulcanoids as small as 15 kilometers across,” said Chapman, a senior scientist at the Southwest Research Institute in Boulder, Colorado. Between February 7 and 11, the wide-angle camera of MESSENGER’s Mercury Dual Imaging System will have snapped 256 images in the areas east and west of the Sun. Because of the danger of the Sun’s glare, the camera will have to peek just past the probe’s sunshade to capture images.

“We are making the same observations on each day,” MESSENGER team member Nancy Chabot explained. “This cadence will allow us to reject cosmic rays and to distinguish, by its motion, the class of each object imaged” (e.g., vulcanoid vs. near- or inner-Earth asteroid).

The team carried out a similar imaging campaign over a nine-day period in June 2008, capturing 240 images of the outer portions of the would-be vulcanoid belt. “This sequence was designed to refine our observing techniques, assess limiting magnitudes, verify detectability of known objects, and make an initial search,” Chapman explained.

“Vulcanoids, should they be found, may provide scientists with insights into the conditions prevalent in the early solar system,” Chapman said. “In particular, if they exist or once existed, they would represent an additional population of impactors that would have cratered no other planet but Mercury, implying that the geological processes on Mercury have happened more recently than we would calculate if we assumed that Mercury’s craters formed at rates equivalent to cratering on the Moon and Mars.”

If vulcanoids are found not to exist, then we could be more confident that most of Mercury’s volcanic plains formed billions of years ago, as on the Moon, according to Chapman. The absence of vulcanoids would also focus scientists’ thinking on why vulcanoids never formed or, if they did form, why they are no longer there.


MESSENGER Thermal Engineer Maintains Cool in Extreme Environs

The Mercury-bound MESSENGER spacecraft will be assaulted by temperatures as high as 700°F as it orbits the planet closest to the Sun, and the only thing that will stand between its room-temperature science instruments and the blistering heat is a handmade ceramic-cloth quilt just one-quarter of an inch thick. Carl Jack Ercol, the man largely responsible for making sure that MESSENGER will be able to stand up to such harsh heat once imagined he’d make his living in a darker, much cooler environment: the coal mining industry. Read more about Ercol at http://messenger.jhuapl.edu/who_we_are/member_focus.html.



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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Old 02-09-2009, 03:25 PM   #34
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Anyway, I still think the "gray" Mercury is more realistic than the "brown" Mercury.
I'm confused.
Mercury has been portrayed as brown in many publications, including Orbiter, yet grey in others.
What is the true colour of Mercury?
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Old 03-20-2009, 09:12 PM   #35
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MESSENGER Mission News
March 20, 2009
http://messenger.jhuapl.edu



MESSENGER Team Remembers Dr. Mario H. Acuña

Mario H. Acuña, a senior astrophysicist at NASA Goddard Space Flight Center and Co-Investigator on the MESSENGER mission, died on March 5, 2009, after a long battle against multiple myeloma. During his four decades at NASA, he played a critical role in many NASA endeavors, serving as principal investigator or key developer of experiments flown on more than 30 missions to every planet in the solar system, as well as the Sun.

Acuña had been involved in the MESSENGER from its inception, 13 years ago. “He became an enthusiastic participant as soon as I mentioned MESSENGER to him, when it was just an idea without an acronym,” notes Stamatios M. Krimigis,chair of MESSENGER’s Atmosphere and Magnetosphere Group. “His deep technical knowledge and scientific insight, coupled with his absolute honesty and integrity made him an indispensable member of any technical review and a critical player when hard decisions had to be made.”

Acuña contributed to the development of the Magnetometer (MAG) and the analysis of MAG observations from MESSENGER's first two flybys of Mercury. “He brought with him a wealth of experience that was truly irreplaceable,” says Brian Anderson, MESSENGER’s Deputy Project Scientist. “He was a fountain of knowledge about anything concerning magnetic fields and magnetometer instrumentation. His breadth of understanding was astonishing. From arcane properties of materials to the intricacies of the electronics design in his instruments, you could count on Mario to have gems of wisdom to offer. To work with Mario on any project was to learn from him. We did our best to be good students, but it will be difficult knowing that we can no longer pick up the phone when we feel the need of his advice.”

Born in Córdoba, Argentina, in 1940, Acuña also brought with him a certain “Argentinean spice,” Anderson says. “Whether it was a novel scientific interpretation that he was determined to get you to take seriously or an engineering detail for calibrating or operating the magnetometer, you always knew where Mario stood, and he was anything but bashful about making his point. Debate was something he loved - the hotter the better! But you could always catch a twinkle in his eye and knew that his heart was with you, and if he was passionate it was because he felt strongly about science and exploration.”

MESSENGER Project Scientist Ralph McNutt knew Acuña since the 1970s, having worked with him on the Voyager 1 mission. “Here you had this brilliant research scientist, but he never had ‘airs’ about him; no pretentions,” McNutt says.

Richard Starr, instrument scientist for the MESSENGERX-Ray Spectrometer, worked with Acuña on several projects, “but the one that stands out the most for me is our collaboration on the X-Ray Spectrometer for the Clark mission.”

Originally scheduled for launch in mid-1996, the Clark spacecraft was to scan Earth with a sophisticated high-resolution camera to provide environmental data. “The Clark mission never launched,” Starr says. “It was canceled by NASA due to cost overruns. But for me personally it was still a great success because of what I learned and accomplished working with Mario. We delivered our instrument on time and on budget.”

Starr also points out that Acuña bridged the gap between scientist and engineer. “For him there really was no difference; it was all part of the same job,” he said. “At Goddard we have the John C. Lindsay Memorial Award for Space Science and the Moe I. Schneebaum Memorial Award for Engineering. As far as I know, Mario is the only person to have won both.”

MESSENGER will enter Mercury’s orbit in less than two years, on March 18, 2011. “While the journey will continue, it won’t be nearly as enjoyable without Mario,” Anderson says. “Perhaps his memory is best served by recalling his devotion to inquiry and advancing human understanding and making sure that the science we do with the MESSENGER magnetometer is up to the Mario Acuña standard.”

For more details, including a blog posted by his family that chronicles the struggle with his illness, visit: http://supermarioAcuña.wordpress.com/.



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.


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Old 04-17-2009, 07:19 PM   #36
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And quite right too

http://messenger.jhuapl.edu/

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Old 05-01-2009, 07:19 AM   #37
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NASA will host a media teleconference on Thursday, April 30, at 2 p.m. EDT.


Quote:
Dwayne Brown
Headquarters, Washington
202-358-1726
[email protected]
Paulette Campbell
Johns Hopkins University Applied Physics Laboratory, Laurel, Md. 240-228-6792 [email protected]
MEDIA ADVISORY: M09-069
NASA TO HOLD BRIEFING TO DISCUSS NEW FINDINGS ABOUT PLANET MERCURY
WASHINGTON -- NASA will host a media teleconference on Thursday, April 30, at 2 p.m. EDT to discuss new data and findings revealed by the Mercury Surface, Space Environment, Geochemistry, and Ranging spacecraft known as MESSENGER.
The spacecraft is the first mission designed to orbit the planet closest to the sun. The probe flew past Mercury on Jan. 14, 2008, and Oct. 6, 2008, conducting the first up-close measurements of the planet since Mariner 10's final flyby on March 16, 1975.
The briefing participants are:
- Marilyn Lindstrom, program scientist, NASA Headquarters in Washington, D.C.
- William McClintock, co-investigator, University of Colorado, Laboratory for Atmospheric and Space Physics in Boulder, Colo.
- James Slavin, co-investigator and chief, Laboratory for Solar and Space Physics, NASA's Goddard Space Flight Center in Greenbelt, Md.
- Thomas Watters, participating scientist, Smithsonian Institution in Washington, D.C.
- Brett Denevi, imaging team member and postdoctoral researcher, Arizona State University in Phoenix
Reporters who would like to participate in the call should submit requests for dial-in instructions to Sonja Alexander at [email protected]. A replay of the teleconference will be available until May 7 by dialing 800-846-6758.
Supporting visuals will be available online April 30 at the start of the teleconference at:
http://messenger.jhuapl.edu/news_room/presscon043009.html
Audio of the teleconference will be streamed live at:
http://www.nasa.gov/newsaudio
-end-
N.

---------- Post added at 08:19 ---------- Previous post was Yesterday at 08:48 ----------

April 30, 2009

Media Contact:
Paulette Campbell
240-228-6792
[email protected]
MESSENGER Reveals Mercury as a Dynamic Planet
Analyses of data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft’s second flyby of Mercury in October 2008 show that the planet’s atmosphere, magnetosphere, and geological past are all characterized by much greater levels of activity than scientists first suspected.

On October 6, 2008, the probe flew by Mercury for the second time, capturing more than 1,200 high-resolution and color images of the planet unveiling another 30 percent of Mercury’s surface that had never before been seen by spacecraft and gathering essential data for planning the remainder of the mission.

“MESSENGER’s second Mercury flyby provided a number of new findings,” says MESSENGER Principal Investigator Sean Solomon at the Carnegie Institution of Washington. “One of the biggest surprises was how strongly the planet’s magnetospheric dynamics changed from what we saw during the first Mercury flyby in January 2008. Another was the discovery of a large and unusually well preserved impact basin that was the focus for concentrated volcanic and deformational activity. The first detection of magnesium in Mercury’s exosphere and neutral tail provides confirmation that magnesium is an important constituent of Mercury’s surface materials. And our nearly global imaging coverage of the surface after this flyby has given us fresh insight into how the planet's crust was formed.”

These findings are reported in four papers published in the May 1 issue of Science magazine.

An Abundance of Magnesium

The probe’s Mercury Atmospheric and Surface Composition Spectrometer, or MASCS, detected significant amounts of magnesium in the planet’s atmosphere, reports William McClintock of the University of Colorado at Boulder’s Laboratory for Atmospheric and Space Physics. “Detecting magnesium was not too surprising, but seeing it in the amounts and distribution we recorded was unexpected,” said McClintock, a MESSENGER co-investigator and lead author of one of the four papers. “This is an example of the kind of individual discoveries that the MESSENGER team will piece together to give us a new picture of how the planet formed and evolved.”

The instrument also measured other exospheric constituents during the October 6 flyby, including calcium and sodium, and he suspects that additional metallic elements from the surface including aluminum, iron, and silicon also contribute to the exosphere.

Radically Different Magnetosphere

MESSENGER observed a radically different magnetosphere at Mercury during its second flyby, compared with its earlier January 14 encounter, writes MESSENGER co-investigator James Slavin, of the NASA Goddard Space Flight Center, lead author of another paper. “During the first flyby, MESSENGER entered through the dusk side of the magnetic tail, measuring relatively calm dipole-like magnetic fields closer to the planet, and then exited the magnetosphere near dawn,” Slavin says. “Important discoveries were made, but scientists didn’t detect any dynamic features, other than some Kelvin-Helmholtz waves along its outer boundary, the magnetopause.”

But the second flyby was a totally different situation, he says. “ MESSENGER measured large magnetic flux leakage through the dayside magnetopause, about a factor of 10 greater than even what is observed at the Earth during its most active intervals. The high rate of solar wind energy input was evident in the great amplitude of the plasma waves and the large magnetic structures measured by the Magnetometer throughout the encounter.”

The magnetospheric variability observed thus far by MESSENGER supports the hypothesis that the great day-to-day changes in Mercury’s atmosphere may be due to changes in the shielding provided by the magnetosphere.

The Rembrandt Basin

One of the most exciting results of MESSENGER’s second flyby of Mercury is the discovery of a previously unknown large impact basin. The Rembrandt basin is more than 700 kilometers (430 miles) in diameter and if formed on the east coast of the United States would span the distance between Washington, D.C., and Boston.

The Rembrandt basin formed about 3.9 billion years ago, near the end of the period of heavy bombardment of the inner Solar System, suggests MESSENGER Participating Scientist Thomas Watters, lead author of another of the papers. Although ancient, the Rembrandt basin is younger than most other known impact basins on Mercury.

“This is the first time we’ve seen terrain exposed on the floor of an impact basin on Mercury that is preserved from when it formed” says Watters. “Landforms such as those revealed on the floor of Rembrandt are usually completely buried by volcanic flows.”

Mercury’s Crustal Evolution

Just over a year ago, half of Mercury was unknown. Globes of the planet were blank on one side. With image data from MESSENGER, scientists have now seen 90 percent of the planet’s surface at high resolution and can start to assess what this global picture is telling us about the history of the planet's crustal evolution, says Brett Denevi, a MESSENGER team member at Arizona State University and lead author of one of the papers.

“After mapping the surface, we see that approximately 40 percent is covered by smooth plains,” she says. “Many of these smooth plains are interpreted to be of volcanic origin, and they are globally distributed (in contrast with the Moon, which has a nearside/farside asymmetry in the abundance of volcanic plains). But we haven’t yet seen evidence for a feldspar-rich crust, which makes up the majority of the lunar highlands and is thought to have formed by flotation during the cooling of an early lunar magma ocean. Instead, much of Mercury's crust may have formed through repeated volcanic eruptions in a manner more similar to the crust of Mars than to that of the Moon.”

Scientists continue to examine data from the first two flybys and are preparing to gather even more information from a third flyby of the planet on September 29, 2009.

“The third Mercury flyby is our final ‘dress rehearsal’ for the main performance of our mission: insertion of our probe into orbit around Mercury in March 2011 and the continuous collection of information about the planet and its environment for one year,” adds Solomon. “The orbital phase of our mission will be like staging two flybys per day. We’ll be drinking from a fire hose of new data, but at least we’ll never be thirsty. Mercury has been coy in revealing its secrets slowly so far, but in less than two years the innermost planet will become a close friend.”


MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.

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Old 05-06-2009, 07:16 AM   #38
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MESSENGER Mission News
May 5, 2009
http://messenger.jhuapl.edu



MESSENGER Co-Investigator Peale Elected to National Academy of Sciences

MESSENGER Co-Investigator Stanton J. Peale, a professor emeritus renowned for his work in planetary science and astrophysics at University of California, Santa Barbara, was among the 72 new members elected to the National Academy of Sciences. The election was held April 28 during the business session of the 146th annual meeting of the Academy. Those elected bring the total number of active members to 2,150, now including four members of the MESSENGER Science Team.

Peale is a leading expert on planetary dynamics. He developed the technique by which MESSENGER will measure the size and state of Mercury's core, and he will lead the interpretation of Mercury Laser Altimeter (MLA) measurements of Mercury's rotation and physical libration.


His theory for Mercury’s forced libration, equivalent to small variations in Mercury's spin rate, was recently utilized to interpret Earth-based radar measurements of Mercury’s motions. Those observations can be explained only if Mercury's core is at least partially molten, a finding that has helped scientists better understand Mercury’s thermal history and the generation of the planet’s intrinsic magnetic field.

As a member of the Academy, Peale will help advise the federal government on science and technology issues. Additional information about the Academy and its members is available online at http://www.nasonline.org.



Mercury Flyby 2, Planned and Actual Images

The April 2009 release to the Planetary Data System of MESSENGER data acquired during the second Mercury flyby offered anew an opportunity to view returned Mercury images adjacent to the simulated version of the same images planned before the flyby. A new version of the Flyby Visualization Tool, called "Mercury Flyby 2, Planned and Actual Images," is available from http://messenger.jhuapl.edu/the_mission/gallery.html and http://messenger.jhuapl.edu/the_mission/visualization.html.

Comparing the planned and acquired images reveals: (1) new details of surface features, (2) different illumination conditions (extent of visible shadows), and (3) the precision of pre-flyby image sequence plans (including camera pointing and prediction of spacecraft location). To simplify use of this tool, no color images are displayed. Each version of the tool utilizes images taken only through one filter out of the full set of 11 filters used for color images with the wide-angle camera.

This version of the Flyby Visualization Tool displays images at 1/4-scale (256-by-256 pixels). The time period highlighted for image sequences shown with this tool, from about 1.5 hours before to 2 hours after closest approach, does not include pre-flyby navigation images and post-flyby "departure movie" images acquired when the spacecraft was far from Mercury.




MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.



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Old 06-26-2009, 08:37 PM   #39
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MESSENGER Mission News
June 26, 2009
http://messenger.jhuapl.edu



Three New Co-Investigators Added to MESSENGER Team

Brian Anderson, Louise Prockter, and Thomas Zurbuchen have been appointed MESSENGER Co-Investigators by NASA Science Mission Directorate Associate Administrator Edward Weiler.

“Each of these individuals has served admirably as MESSENGER Instrument Scientists, and each has led an important aspect of the analysis and interpretation of MESSENGER observations from the first two Mercury flybys,” notes MESSENGER Principal Investigator Sean Solomon.

As a MESSENGER Deputy Project Scientist, Anderson, of the Johns Hopkins University Applied Physics Laboratory (APL), oversees the orbital operations planning to ensure that observations from all of the instruments are coordinated to meet the mission objectives. He formerly served as the Magnotometer Instrument Scientist. In his additional role as Co-Investigator, Anderson will provide scientific direction to the operation of the Magnetometer instrument in orbit, including in-flight calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments closely related to investigation of Mercury's magnetic field. In addition, he will lead aspects of the science analysis of data from the Magnetometer and other instruments in understanding Mercury's internal magnetic field and magnetosphere, particularly efforts to identify and quantify the magnetospheric contributions to the observations so as to recover the structure of Mercury's internal magnetic field to the highest fidelity possible.

Prockter, also of APL, serves as the Instrument Scientist for the Mercury Dual Imaging System (MDIS). In her new role as Co-Investigator, she will provide scientific direction to the operation of MDIS in Mercury orbit, including instrument calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments related to observations of Mercury's surface. In addition, she will lead aspects of the science analysis of MDIS observations to improve our understanding of the geological evolution of Mercury, particularly the study of impact melting during the formation of large craters and basins on Mercury and the contribution of impact melts to smooth plains deposits.

Zurbuchen, of the University of Michigan, is the Instrument Scientist for the Energetic Particle and Plasma Spectrometer. As a Co-Investigator, he will provide scientific direction to the operation of the Fast Imaging Plasma Spectrometer (FIPS) sensor in orbit, including calibration, data validation, science product generation, and coordination with the operation of and data returned from other instruments sensitive to the exosphere and magnetosphere. He will also lead aspects of the science analysis of data from FIPS and other instruments in understanding Mercury's charged particle environment, particularly the analysis of the distribution of plasma ions in Mercury's vicinity and the implications of their energies and compositions for magnetosphere-solar wind interaction at Mercury.

“MESSENGER is one of the most important things I am working on and has accompanied me and my team for over 10 years,” Zurbuchen says. “We look forward to the next 10 years of science data and breakthroughs that will come from MESSENGER, and particularly from the Fast Imaging Plasma Spectrometer.”



MESSENGER Engineer Helps Manage Probe’s Data

Like many young boys of his generation, MESSENGER Team Member Ray Espiritu grew up wanting to fly through space and to design video games. A lack of perfect vision and color blindness prevented him from becoming an astronaut. So, armed with a B.S. in mechanical engineering and a master’s in astronautical engineering, he set to make his mark as a satellite missions operations engineer. To read about how Espiritu and his colleagues at Applied Coherent Technology (ACT), Inc., help preserve the science that fulfills objectives of the MESSENGER mission, click here.



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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Old 08-03-2009, 06:10 PM   #40
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MESSENGER Mission News
August 3, 2009
http://messenger.jhuapl.edu



MESSENGER Mission Passes Five-Year Mark

It’s been five years since MESSENGER was launched atop a Delta II rocket on August 3, 2004, and they have been busy years. It has been a long journey, says MESSENGER Mission Operations Manager Andy Calloway, “not just in distance travelled – just over 3.5 billion miles so far – but also in terms of significant milestones and accomplishments.”

MESSENGER has executed five planetary flybys – one of Earth on August 2, 2005; two of Venus, on October 24, 2006, and June 5, 2007; and two of Mercury, on January 14, 2008, and October 6, 2008. “These were not merely gravity assists, but also major science data collection endeavors that required months of detailed planning,” says Calloway of the Johns Hopkins University Applied Physics Laboratory (APL).

The probe has completed four major deep-space maneuvers (DSMs) and 12 trajectory-correction maneuvers, and mission controllers have been able to forgo six additional planned course corrections by using MESSENGER’s solar panels creatively, harnessing solar radiation pressure to adjust the spacecraft’s trajectory.

Because of the implementation of solar sailing, the MESSENGER team has not used propellant to correct the cruise trajectory of the spacecraft since December 19, 2007, in advance of the first Mercury flyby,” says MESSENGER Mission Systems Engineer Eric Finnegan, of APL. He credits a solar sailing team of engineers – Ken Williams in navigation, Jim McAdams in trajectory design, and Dan O’Shaughnessy in guidance and control – “for increasing mission performance while lowering mission risk by making this technique operational.”

Over the years, MESSENGER’s circuitous journey has presented opportunities within challenges. “We’ve been through periodic extended communication outages as the spacecraft travels on the far side of the Sun from Earth during superior solar conjunctions and frequent close passages by the Sun during perihelion crossings,” Calloway says. “But MESSENGER has traveled as close to the Sun as only three tenths of the Earth-Sun distance during these crossings, providing valuable information and experience in preparation for orbital operations, which begin following the critical Mercury orbit insertion maneuver in 2011.”

In addition to nine major instrument software loads during these five years (with two more planned this month), the third main processor flight software update of the mission was successfully completed on July 14, 2009.

“This new software significantly increases the spacecraft's capabilities for the upcoming orbital phase,” Calloway says. “These processor loads require months of testing, and then once the software is loaded to the spacecraft, the processor has to be rebooted for it to take effect. This rebooting results in a transition to a Sun-safe rotisserie mode in which the spacecraft transmits a beacon signal as it rotates slowly every 3.5 hours. Operators in the control center monitored the signal as it briefly swept through the ground station's field of view one rotation after the reboot, and seven hours later they sent a command with precise timing to halt the rotation and begin restoring the spacecraft to its nominal operational mode.”

More than 90% of Mercury’s surface has now been imaged after MESSENGER's flybys, including territory never seen before by spacecraft, and planning is in full swing for the orbital phase of the mission. Up next is a third pass by Mercury on September 29, 2009, a fifth DSM on November 24, 2009, and then on March 18, 2011, MESSENGER will become the first spacecraft to enter into orbit around the innermost planet.

“When MESSENGER launched five years ago, even our first encounter with Mercury seemed far off,” recounts MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “Our first two Mercury flybys last year produced an explosion of new and exciting observations, and our cruise through the inner Solar System as of this important anniversary is more than 75% complete. The entire MESSENGER team is eagerly awaiting the first observations of Mercury from orbit.”



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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MESSENGER Mission News
August 20, 2009
http://messenger.jhuapl.edu



Upcoming Mercury Encounter Presents New Opportunities for Magnetometer

On September 29, the MESSENGER spacecraft will pass by Mercury for the third time, flying 141.7 miles above the planet’s rocky surface for a final gravity assist that will enable it to enter orbit about Mercury in 2011. This encounter will also provide new observational opportunities for MESSENGER’s Magnetometer, designed to determine the structure and origin of Mercury's intrinsic magnetic field.

The comparison of magnetosphere observations from MESSENGER's first flyby in January 2008 with data from the probe's second pass in October 2008 provided key new insight into the nature of the planet’s internal magnetic field and revealed new features of Mercury’s magnetosphere, explains Brian Anderson, of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md.

“MESSENGER’s first flyby of Mercury and Mariner 10’s encounters with the planet provided data only from Mercury's eastern hemisphere,” says Anderson, MESSENGER’s Deputy Project Scientist. “The October 2008 flyby provided the first measurements from Mercury’s western hemisphere, and scientists learned that the planet's magnetic field is highly symmetric. This finding is significant for the planet’s internal field because it implies that the dipole is even more closely aligned with the planet's rotation axis than we could conclude before the second flyby.”

The probe’s third flyby of Mercury next month will take it again over the planet’s western hemisphere, and the observations will be used to refine the estimate of the planetary magnetic field, Anderson explains.

“The previous flybys yielded significant insight into the dynamics of Mercury’s magnetosphere and its boundaries,” Anderson says. “During the second flyby a plasmoid and a series of traveling compression regions were observed in Mercury’s magnetotail, and a large flux transfer event was observed at the dayside magnetopause. These observations proved that the solar wind interaction, under the right circumstances, can drive intense magnetic reconnection at rates 10 times the rates observed at Earth.”

The behavior during the second flyby was markedly different from that found in the first flyby, demonstrating the profound influence of the solar wind environment on Mercury’s magnetosphere. “The third flyby is the last opportunity to survey the magnetotail and magnetopause regions in the equatorial plane, and the contrast in the system’s structure under different solar wind conditions already observed make it likely that the third flyby will yield new insights and perhaps more surprises for the dynamics of this smallest and most highly variable of the solar system’s planetary magnetospheres,” Anderson says.

As with the previous two flybys, the Magnetometer will record the magnetic field at the highest available observation rate of 20 vector magnetic field samples per second for a period of twelve hours centered on the time of closest approach. “This observing plan guarantees the highest possible science return from the encounter and will provide key observations to guide the magnetic field investigation plan for the prime orbital phase of the mission,” Anderson says.



Berkel Leaves Its Mark

The crater in the lower left corner of this image is Berkel, recently named for Turkish painter and printmaker Sabri Berkel (1909-1993). The crater contains dark material in its center and in a ring immediately surrounding it. Moreover, Berkel is surrounded by a blanket of bright ejecta and a system of bright rays. Other craters on Mercury’s surface, such as Basho, also exhibit both bright rays and dark halos. In contrast, two neighboring craters in this image (indicated by white arrows) have bright rays but lack dark halos. Members of the MESSENGER Science Team are investigating why some craters contain dark material while others do not, and what that means for the nature and structure of Mercury's crust. To view other images released over the summer, go online to http://messenger.jhuapl.edu/gallery/sciencePhotos/index.php.


MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.
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Old 09-16-2009, 07:30 PM   #42
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MESSENGER Mission News
September 16, 2009
http://messenger.jhuapl.edu



MESSENGER Team Prepares for Third Flyby, Rehearses for Orbital Operations

In less than two weeks, on September 29, MESSENGER will fly by Mercury for the third and final time, a maneuver key to placing the probe on a trajectory that will enable its March 2011 insertion into orbit about Mercury. Even as the team readies for this critical event, a parallel effort has long been underway to prepare MESSENGER for the main event.
Since January, the team has been staging orbital operations rehearsal tests, called week-in-the-life (WITL) tests, to try out the new procedures and software being developed for the Mercury orbital mission. Next month, they will wrap up the second such test, and the results of these exercises are proving pivotal to the team’s plan.
“Because no spacecraft has orbited the planet Mercury before, we do not have any direct experience planning and scheduling science observations in such an environment,” explains Alice Berman, MESSENGER’s Payload Operations Manager. “Therefore, a comprehensive orbital operations readiness plan is underway to ensure that the mission’s full science success criteria can be met by the time that the nominal mission ends on 17 March 2012. The WITL tests, meant to simulate several realistic weeks of orbital operations, are an integral part of this overall readiness plan.”
Between 2009 and 2010, the team will run at least seven WITLs covering different weeks and orbital conditions. “It’s critical to test as many different observing scenarios and orbital conditions that will occur during the orbital mission as possible,” Berman says.
The first WITL test ran from January to April. The team chose to rehearse the planning and scheduling for a week in mid-October 2011, when the level of instrument commanding is not extremely demanding. The focus of WITL-1 was primarily on new procedures and software that had recently been developed. “We wanted to walk through all the processing steps of preparing a weekly command load, with careful attention to the newly developing software tools,” Berman recounts.
At an all-day workshop in February, the instrument teams worked through the required steps for preparing and delivering their WITL-1 instrument sequences to the mission operations team. The mission operations team then built the spacecraft command load – adding the necessary spacecraft commanding (e.g., solar array commanding, spacecraft downlinks) – and ran it on the MESSENGER hardware simulator. With that done, the mission operations and science operations teams reviewed the results.
A debriefing meeting was held in April to review the success of the test and gather the issues to be addressed and lessons learned prior to starting the next rehearsal test. “We learned that we need to have an extremely easy and efficient process, because we must start a new command load each week,” Berman explains. “We need a way to automatically keep track of status and approvals and to notify team members when their attention or action is needed. We found a project management software called JIRA that will help us do all this. We learned a lot about what our current tools can do (and what they cannot), and we are prioritizing the required software fixes and enhancements now.”
The second WITL test began in July 2009 and will be completed in October. “In addition to testing the improved the orbital planning processes and software, WITL-2 is focusing on a different timeframe of the orbital mission, so that different instrument and spacecraft components will be tested,” Berman says. “Right now the mission operations team is building the WITL-2 integrated command load, and then it will be tested on the MESSENGER hardware simulator.”
The remaining WITL tests will be conducted in 2010, and the team is currently developing the schedule and scope of these tests. “In 2010, the WITL tests will overlap in time so that the teams can exercise the process of working on more than one weekly command load at one time,” Berman notes. “We will carefully assess what works well and what does not, and we will update our processes and software tools with the lessons learned from each WITL test.”
“Once in orbit, our near-term scheduling strategy will be to prepare and upload a new command load (containing both instrument and spacecraft instructions) once per week,” Berman adds. “This work will require the close coordination of both the science and mission operations teams. We believe that it will take approximately three weeks to prepare each command load, so the science and mission operations teams will be working on more than one command load at any given time.”



On Target for Mercury Flyby 3

The MESSENGER spacecraft will pass 228 kilometers (142 miles) above Mercury's surface on September 29 for the mission's third flyby of the Solar System's innermost planet. The MESSENGER team has been working on the flyby observation plans for months. Three of the highlights for MDIS include:
  • <LI style="mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1" class=MsoNormal>NAC approach mosaic. This mosaic will provide the first close-up images of a portion of Mercury's surface by spacecraft. (That portion of the surface appears as a featureless white strip near the limb of the planet in the top image.) <LI style="COLOR: black; mso-margin-top-alt: auto; mso-margin-bottom-alt: auto; mso-list: l0 level1 lfo1" class=MsoNormal>WAC and MASCS targeted observations. Unlike the neatly arranged rows and columns of most MDIS mosaics, for these observations WAC images in 11 color filters will be acquired as MASCS collects high-quality spectral measurements of specific targets of interest. Visit this page to learn more about these targeted observations.
  • NAC departure high-resolution southern hemisphere mosaic. This large 15-column by 13-row mosaic will provide new detail for an area of Mercury's surface in the southern hemisphere and will be complementary to a high-resolution mosaic of the northern hemisphere obtained during Mercury flyby 2.
On September 23, NASA will host a media teleconference previewing the flyby. Details of that event will be posted online at http://messenger.jhuapl.edu/news_room/index.php.


MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.


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Old 09-16-2009, 07:37 PM   #43
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Go MErcury Space, Space ENvironment, GEochemistry and Ranging, Go!


228 km is a nice one! Can't wait to see the close-ups.
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Old 09-22-2009, 06:29 PM   #44
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Dwayne Brown
Headquarters, Washington Sept. 21, 2009
202-358-1726
[email protected]

Paulette Campbell
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
240-228-6792
[email protected]

MEDIA ADVISORY: M09-181

NASA TO PREVIEW MISSION'S THIRD FLIGHT PAST MERCURY

WASHINGTON -- NASA will host a media teleconference at 1 p.m. EDT on Wednesday, Sept. 23, to preview the third and final flyby of Mercury by the Mercury Surface, Space Environment, Geochemistry, and Ranging spacecraft known as MESSENGER.

On Sept. 29, the spacecraft will swing less than 142 miles above the planet's rocky surface for a final gravity assist that will enable it to enter orbit around Mercury in March 2011. With more than 90 percent of the planet's surface imaged after the spacecraft's second flyby, the team will focus instruments on questions raised by the earlier flybys to advance our understanding of the planet closest to the sun.

The briefing participants are:
- Anthony Carro, MESSENGER program executive, NASA Headquarters in Washington
- Eric J. Finnegan, mission systems engineer, Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
- Noam R. Izenberg, Mercury Atmospheric and Surface Composition Spectrometer instrument scientist, Johns Hopkins University Applied Physics Laboratory
- Sean C. Solomon, principal investigator, Carnegie Institution of Washington

To participate in the teleconference, reporters should e-mail Dwayne Brown at [email protected] for dial-in and passcode information.

Audio of the teleconference will be streamed live at:




At the beginning of the briefing, related images will be available at:


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Old 09-24-2009, 06:54 PM   #45
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For Immediate Release
September 23, 2009


Media Contact: Paulette Campbell
(240) 228-6792
[email protected]

MESSENGER Prepares for Final Pass by Mercury
On September 29, 2009, the MESSENGER spacecraft will fly by Mercury for the third and final time, passing 141.7 miles above the planet’s rocky surface for a final gravity assist that will enable it to enter orbit about Mercury in 2011. With more than 90 percent of the planet’s surface already imaged, the team will turn its instruments during this flyby to specific features to uncover more information about the planet closest to the Sun.
“The first two flybys of Mercury revealed nearly half of the planet in detail for the first time,” notes MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “During this third encounter, the MESSENGER camera will again image areas never before seen at close range, and we will obtain color images of other regions at resolutions superior to those of previous observations. Our other instruments will target interesting areas of the surface, atmosphere, and magnetosphere for detailed measurements designed to address questions raised by observations made during the earlier flybys.”
Depending on the activity of the Sun, Solomon adds, MESSENGER might also view yet another distinct snapshot of how the planet interacts with conditions in interplanetary space driven by the behavior of our nearest star.
Peering through Mercury’s Exosphere
The first two flybys provided an unprecedented glimpse into the structure of the planet’s tenuous exosphere and the processes behind it. During this encounter, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) will again make high-spectral- and high-spatial-resolution measurements of Mercury’s exosphere.
“Targeted scans of the planet’s comet-like tail by the MASCS Ultraviolet and Visible Spectrometer will permit a search for temporal variability in both the sodium and calcium components,” notes MASCS Instrument Scientist Noam Izenberg of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md. “In addition, we will target the north- and south-polar regions for detailed observations of those species, and we will look for several new exospheric species.”
A Few New Pictures
The Mercury Dual Imaging System (MDIS) will capture 1,559 pictures of the planet. “Using all 11 filters of the wide-angle camera, we are going to collect high-resolution, color images of scientifically interesting targets that we identified from the second flyby, and at the same time MASCS will observe those same targets,” explains APL’s Ralph McNutt, MESSENGER Project Scientist.
As MESSENGER approaches Mercury, MDIS’s narrow-angle camera (NAC) will capture images of previously unseen terrain. Later, as the spacecraft departs, the NAC will take high-resolution images of the southern hemisphere that will be used to create a mosaic to complement the high-resolution, northern-hemisphere mosaic obtained during the second Mercury flyby.
Images captured eight days before and 21 days after the probe’s closest approach to Mercury will allow MESSENGER scientists to create detailed phase curves of Mercury at multiple wavelengths, and searches will be conducted for possible satellites of Mercury as small as 100 meters in diameter.
Combing the Surface
Determining the composition of Mercury's surface is a major goal of the orbital phase of the mission, and during this flyby the instruments focused on compositional measurements will have a third opportunity to observe Mercury.
The MASCS sensors – both UVVS and the Visible and Infrared Spectrograph – will spend about 30 seconds on each of 11 targets, two at locations also targeted for photometry, focusing on end-member compositional characteristics identified during the second flyby. The X-Ray Spectrometer will once again look for X-ray fluorescence from surface elements, depending on the level of solar activity, and the Gamma-Ray Spectrometer will acquire more counting data from approximately the same region that it surveyed during the second flyby.
The Neutron Spectrometer will use two spacecraft maneuvers to provide better Doppler filtering of encountered neutron fluxes, including a 180° spacecraft roll on the night side (inbound) and a 45° roll on the dayside (outbound). The nightside maneuver will provide more information on the composition on the side of the planet away from that sampled during the first flyby, and the combination of dayside and night-side measurements will enable a test of the influence of planetary surface temperature on the thermal neutron fluxes, data important for properly interpreting the neutron fluxes to be measured during the orbital phase of the mission.
MESSENGER’s third Mercury flyby will provide more data on the correlation between high-resolution topography and high-resolution images of Mercury. The Mercury Laser Altimeter (MLA) will range to Mercury's surface and make a topographic profile along the instrument ground track. A shift in the longitude of closest approach by 17° to the west and 3° north from the position of closest approach for the second flyby will allow the data from the third flyby to augment and complement those from the second flyby. In addition, the slower flyby speed (approximately 1.5 kilometers per second slower relative to the center of Mercury) will keep the trajectory closer to the planet longer.
“The data we gather will provide additional topography of surface features on Mercury for our ongoing studies of the morphology of craters and tectonic structures, such as thrust faults,” says MLA Instrument Scientist Olivier Barnouin-Jha of APL. “It will also extend our equatorial view of Mercury’s global shape and allow us to confirm the discovery made during the first and second flyby of MESSENGER that Mercury’s equatorial region possesses a slightly elliptical shape.”
Surprises about Mercury’s Magnetic Field
The third Mercury encounter could reveal surprises about the planet’s magnetic field, says MESSENGER Deputy Project Scientist Brian Anderson, of APL. “The first two flybys took the spacecraft over opposite sides of the planet – over the eastern hemisphere in January 2008 and the western side in October 2008,” Anderson notes. “The third flyby will take it again over the planet’s western hemisphere, and the observations will be used to refine the estimate of the planet’s internal magnetic field.”
Anderson says this flyby is the last opportunity to survey the magnetotail and magnetopause regions in the equatorial plane. “The contrast in the system’s structure under different solar wind conditions already observed make it likely that the third flyby will yield new insights and perhaps more surprises regarding the dynamics of this smallest and most highly variable of the solar system’s planetary magnetospheres,” he adds.
As with the previous two flybys, the Magnetometer will record the magnetic field at the highest available observation rate of 20 vector magnetic field samples per second for a period of twelve hours centered on the time of closest approach. “This observing plan guarantees the highest possible science return from the encounter and will provide key observations to guide the magnetic field investigation plan for the prime orbital phase of the mission,” Anderson says.
”This flyby will not only be our last close look at the equatorial regions of Mercury, it is our final planetary gravity assist, and it will be important for the entire encounter to be executed as planned,” summarizes Solomon. “As enticing as these flybys have been for discovering some of Mercury’s secrets, they are the hors d’oeurves to the mission’s main course, observing Mercury from orbit for an entire year.”



MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.




---------- Post added at 19:54 ---------- Previous post was at 07:04 ----------

September 24, 2009

Media Contact: Paulette Campbell
240-228-6792
[email protected]

Media Invited to Join MESSENGER Team for Mercury Closest Approach

At 5:55 p.m. on September 29, MESSENGER will fly 142 miles above the cratered surface of Mercury for the third and final time. The goal of the flyby is to adjust MESSENGER’s orbit so that it more closely matches that of Mercury, which will allow the spacecraft to be inserted into orbit about the innermost planet on March 18, 2011. During this encounter MESSENGER will have nearly the same view of Mercury as it did during its second flyby on October 6, 2008, so the team is planning targeted observations that build on the discoveries of the first two flybys.

Reporters are invited to the MESSENGER Situation Room at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., 5:00 p.m. – 7:00 p.m. on Tuesday, September 29, 2009, to watch operators maneuver the spacecraft through closest approach. Members of the MESSENGER operations and science teams will be available to discuss the mission and Mercury flyby activities.

Space is limited, and registration is required. Reporters interested in attending should contact Paulette Campbell at (240) 778-6792 or [email protected] by September 28, 2009.

MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as principal investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA. Visit http://messenger.jhuapl.edu/ for the latest images from Jupiter and mission status reports.



The Applied Physics Laboratory, a division of The Johns Hopkins University, meets critical national challenges through the innovative application of science and technology. For more information, visit www.jhuapl.edu.
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