Orbiter-Forum  

Go Back   Orbiter-Forum > Far Side of the Moon > Spaceflight News
Register Blogs Orbinauts List Social Groups FAQ Projects Mark Forums Read

Spaceflight News Share news, stories, or discussions about government and private spaceflight programs; including ESA, ISS, NASA, Russian Space Program, Virgin Galactic, & more!

Reply
 
Thread Tools
  #1  
Old
Notebook's Avatar
Notebook Notebook is offline
Donator


Default MESSENGER Mission News
by Notebook 03-20-2008, 06:07 AM

MESSENGER Mission News
March 19, 2008
http://messenger.jhuapl.edu

Critical Deep-Space Maneuver Targets MESSENGER for Its Second Mercury Encounter

The MESSENGER spacecraft delivered a critical deep-space maneuver today – 64 million miles (103 million kilometers) from Earth – successfully firing its large bi-propellant engine to change the probe’s trajectory and target it for its second flyby of Mercury on October 6, 2008. This was the first trajectory-correction maneuver (TCM) t
o test the continuous slow rotation of the spacecraft throughout the burn, essential for the March 18, 2011, Mercury orbit-insertion (MOI) maneuver.

“Every propulsive event in this complex mission is an important step toward our ultimate goal – placing the first spacecraft into orbit about the innermost planet,” offers MESSENGER Principal Investigator Sean Solomon, of the Carnegie Institution of Washington. “Today’s deep-space maneuver is a crucial milestone that points us cleanly toward our next close look at Mercury in October.”

The 149-second maneuver began at 3:30 p.m. EDT. Mission controllers at The Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., verified the start of the maneuver about 5 minutes 42 seconds later, when the first signals indicating spacecraft thruster activity reached NASA’s Deep Space Network tracking station outside Goldstone, California.
The continuous rotation of the spacecraft occurred during the 90-second firing of the large bi-propellant engine, the main part of the 149-second TCM, and was less than 4° – about 11% of the turn required for the mission-critical MOI. The total change in velocity of 72.2 meters per second (161.5 miles per hour) achieved during the maneuver will increase the spacecraft’s speed relative to the Sun.
This was the third of five deep-space maneuvers that will help the spacecraft reach Mercury orbit. The first, on December 12, 2005, positioned the probe for its October 2006 flyby of Venus; the second, on October 17, 2007, targeted MESSENGER for its first flyby of Mercury this January.

DSM-4 on December 6, 2008, will position MESSENGER for Mercury flyby 3, scheduled for September 30, 2009. And the final deep-space maneuver on November 29, 2009, will target the probe for Mercury orbit insertion.

The next maneuver, TCM-24, is currently scheduled for April 24 and will be used to further fine-tune the trajectory for the second Mercury encounter. “There are also several instrument and subsystem calibrations this spring and summer, and even an instrument flight software load in July,” says MESSENGER Mission Operations Manager Andy Calloway of APL. “The MESSENGER team will also continue to focus on the Mercury Flyby 2 sequence planning and testing, as well as orbital operations planning in parallel with the ongoing flight operations.”



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.

Reply With Quote
Views 124984 Comments 290
Total Comments 290

Comments

Old 05-30-2008, 02:15 PM   #2
Notebook
Donator
 
Notebook's Avatar


Default

May 30, 2008
http://messenger.jhuapl.edu


The Mastermind behind MESSENGER’s Trajectory Honored for Efforts

Jim McAdams, the MESSENGER mission design lead engineer, was named the 2008 Engineer of the Year by the Baltimore Section, American Institute of Aeronautics and Astronautics (AIAA). Each spring, this chapter of AIAA honors those in the aerospace community who have made significant contributions during the previous year.

McAdams of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., “optimized the trajectory and maneuver schedule, designing one of the most challenging planetary missions in history,” said APL’s Tom Strikwerda, who on May 28 presented the award: a plaque and a 24-inch-high trophy that McAdams will keep until passing it on to the next winner a year from now.

Because Mercury lies deep within the Sun’s gravity well, travel to the planet requires an extremely large velocity change. A spacecraft travelling to Mercury speeds up as it falls toward the Sun; so MESSENGER’s trajectory had to be designed to most effectively utilize the gravitational pull of Venus and Mercury to achieve most of the required velocity change.

To make the trip possible, the trajectory uses six gravity-assist flybys: one by Earth, two by Venus, and three by Mercury. These gravity-assists, along with five large course-correction maneuvers, reduce the energy (and thus fuel) requirements but greatly prolong the trip. These maneuvers will also slow the spacecraft’s speed just enough relative to Mercury to enable its thruster to place the probe into orbit around Mercury.

Upon arrival at Mercury in March of 2011 the spacecraft will enter an elliptical orbit that passes as close as 200 kilometers to Mercury’s far northern surface every 12 hours. Such an orbit will allow MESSENGER to measure solar wind and magnetic fields at a variety of distances from the planet yet still obtain close-up measurements and images of the surface.

“The implementation of this complex mission plan has been a significant challenge,” says McAdams, who also worked on the Near Earth Asteroid Rendezvous mission. “It’s a privilege to join two other MESSENGER team engineers as recipients of this award,” he adds, referring to Robin Vaughan and Adrian Hill, two other engineers from the team who received the award in 2004 and 2006, respectively.

McAdams, who holds an M.S. in Aeronautical and Astronautical Engineering from Purdue University, also created and led the development of MESSENGER education and outreach products, as well as trajectory data distribution to the science community. Last summer, he played a critical role in the creation of the Mercury Flyby Visualization Tool, which provides simulated views of Mercury from MESSENGER’s perspective, during approach, flyby, and departure, or in real time (as the observations actually occur).

Members of MESSENGER’s Geology Discipline Group used the tool both before and after the probe’s first flyby of Mercury in January to gain information about imaging sites on Mercury. The tool will be updated for upcoming Mercury encounters.

Jim McAdams has been a critical member of the MESSENGER team,” offers MESSENGER Principal Investigator Sean Solomon. “Jim is usually several steps ahead of the rest of us with respect to planning for mission-critical events, and we can always count on his results to high precision. The journey to orbiting Mercury is long and complex, but we have a terrific guide.”

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.
Notebook is offline   Reply With Quote
Old 07-02-2008, 04:06 PM   #3
Notebook
Donator
 
Notebook's Avatar


Default

J. D. Harrington
NASA Headquarters, Washington
1-202-358-5241
[email protected]

Paulette Campbell
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
1-240-228-6792
[email protected]

MEDIA ADVISORY: M08-128

NASA TO REVEAL NEW DISCOVERIES FROM MERCURY

WASHINGTON -- NASA will host a media teleconference Thursday, July 3, at 2 p.m. EDT, to discuss analysis of data from the Mercury Surface, Space Environment, Geochemistry and Ranging (MESSENGER) spacecraft's flyby of Mercury earlier this year.

The spacecraft is the first designed to orbit the planet closest to the sun. It flew past Mercury on Jan. 14, 2008, and made the first up-close measurements since Mariner 10's final flyby in 1975.

Analyses of the data show volcanoes were involved in the formation of plains. The data also suggest the planet's magnetic field is actively produced in its core. In addition, the mission has provided the first look at the chemical composition of Mercury's surface. The results will be reported in a series of 11 papers published July 4 in a special section of Science magazine.

The teleconference participants are:
- Marilyn Lindstrom, program scientist, NASA Headquarters
- Sean Solomon, principal investigator, Carnegie Institution of Washington
- James W. Head III, professor of geological sciences, Brown University, Providence, R.I.
- William McClintock, senior research associate, Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder
- Thomas H. Zurbuchen, associate professor, Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor

Reporters may access the embargoed science press package materials by registering with EurekAlert! at www.eurekalert.org and e-mailing [email protected] to expedite their registration. Once registered, they may log in directly at: http://www.eurekalert.org/jrnls/sci/.

To participate in the teleconference, reporters in the United States should call 1-888-455-3616 and use the passcode "messenger." International reporters should call 1-517-623-4705. Audio of the teleconference will be streamed live at: http://www.nasa.gov/newsaudio.

When the briefing begins, related images will be available at: http://messenger.jhuapl.edu/news_room/telecon4.html.

July 3, 2008


Media Contacts:

Tina McDowell
Carnegie Institution of Washington
(202) 939-1120

[email protected]


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

Edit:------------------------------------------------------------------------------------------------------------------

MESSENGER Settles old Debates and Makes new Discoveries at Mercury
Scientists have argued about the origins of Mercury’s smooth plains and the source of its magnetic field for over 30 years. Now, analyses of data from the January 2008 flyby of the planet by the MESSENGER spacecraft have shown that volcanoes were involved in plains formation and suggest that its magnetic field is actively produced in the planet’s core and is not a frozen relic. Scientists additionally took their first look at the chemical composition the planet’s surface material. The tiny craft probed the composition of Mercury’s thin atmosphere, sampled charged particles (ions) near the planet, and demonstrated new links between both sets of observations and materials on Mercury’s surface. The results are reported in a series of 11 papers published in a special section of the July 4 issue of Science magazine.
The controversy over the origin of Mercury’s smooth plains began with the 1972 Apollo 16 Moon mission, which suggested that some lunar plains came from material that was ejected by large impacts and then formed smooth ‘ponds.’ When Mariner 10 imaged similar formations on Mercury in 1975, some scientists believed that the same processes were at work. Others thought that Mercury’s plains material came from erupted lavas, but the absence of volcanic vents or other volcanic features in images from that mission prevented a consensus.
Six of the papers in Science report on analyses of the planet’s surface through its reflectance and color variation, surface chemistry, high-resolution imaging at different wavelengths, and altitude measurements. The researchers found evidence of volcanic ventsalong the margins of the Caloris basin, one of the Solar System’s largest and youngest impact basins. They also found that Caloris has a much more complicated geologic history than previously believed.
“By combining Mariner 10 and MESSENGER data, the science team was able to reconstruct a comprehensive geologic history of the entire basin interior,” explained James Head of Brown University, the lead author of one of the Science reports. “The Caloris basin was formed from an impact by an asteroid or comet during the heavy bombardment period in the first billion years of Solar System history. As with the lunar maria, a period of volcanic activity produced lava flows that filled the basin interior. This volcanism produced the comparatively light, red material of the interior plains intermingled with impact crater deposits. Subsidence caused the surface of the Caloris floor to shorten, producing what we call wrinkle-ridges. The large troughs, or graben, then formed as a result of later uplift, and more recent impacts yielded newer craters.”
The first altitude measurements from any spacecraft at Mercury also found that craters on that planet are about a factor of two shallower than those on the Moon and they, too, show a complex geologic history.
Mariner 10 discovered Mercury’s magnetic field. Earth is the only other terrestrial planet with a global magnetic field. In both cases the field produces a protective bubble called a magnetosphere, which generally shields the planet surface from the charged particles of the solar wind. Earth’s magnetic field is generated by the churning, hot, liquid-iron core via a mechanism called a magnetic dynamo. Researchers have been puzzled by Mercury’s field since its iron core should have cooled long ago and stopped generating magnetism. Some researchers have thought that the field may have been a relic of the past, frozen in the outer crust.
“MESSENGER’s measurements did indicate that, like the Earth, Mercury’s magnetic field is mostly dipolar, which means it has a north and south magnetic poles,” stated lead author Brian Anderson of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md. “The fact that it’s dipolar, and that we did not find the ‘signature’ shorter-wavelength anomalies that would signify patches of magnetized crust, supports the view that we’re seeing a modern dynamo.We are eager for the October flyby and the year in orbit to see if this is the case elsewhere on the planet and confirm that the field comes from the core.”
The flyby made the first-ever observations of the ionized particles in Mercury’s unique exosphere. The exosphere is an ultrathin atmosphere where the molecules are so far apart they are more likely to collide with the surface than with each other. The planet’s highly elliptical orbit, its slow rotation, and particle interactions with the magnetosphere, interplanetary medium, and solar wind result in strong seasonal and day-night differences in the way particles behave.
“MESSENGER was able to observe Mercury’s exosphere in three areas—the dayside, the day/night line, or terminator, and its 25,000 mile-long (40,000 km) sodium tail,” explained lead author Bill McClintock of the University of Colorado. “Atoms of hydrogen, helium, sodium, potassium, and calcium have been seen in the exosphere, and many other elements almost certainly exist there. When species escape from the surface they are accelerated by solar-radiation pressure and form a long tail of atoms flowing away from the Sun. But their abundances differ depending on whether it’s day or night, effects from the magnetic field and solar wind, and possibly the latitude. Mercury’s exosphere is remarkably active.”
“Since Mariner 10’s discovery of Mercury’s magnetosphere, there’s been speculation about its dynamics, ion composition, and how the solar wind interacts with the surface and exosphere,” commented lead author Thomas Zurbuchen of the University of Michigan. “The planet’s surface is the most space-weathered of any terrestrial planet, and the interaction of solar wind and micrometeoroid flux with the surface can inject both neutral and charged particles into the exosphere and space. The ion composition was not measured by Mariner 10 and MESSENGER once again provided a significant scientific surprise. The magnetosphere is full of many ionic species, both atomic and molecular and in a variety of charge states. What is in some sense a ‘Mercury plasma nebula’ is far richer in complexity and makeup than the Io plasma torus in the Jupiter system. The abundances of silicon, sodium, and sulfur relative to oxygen in the solar wind are too low, and their charge states — ionization — are too high to account for the abundances we measured, so there is no doubt that this material came from the planet’s surface. This observation means that this flyby got the first-ever look at surface composition.”
Mercury’s core makes up 60% of its mass, which is at least twice as large as any other planet. The flyby revealed that the magnetic field, originating in the outer core and powered by core cooling, drives very dynamic and complex interactions among the planet’s interior, surface, exosphere, and magnetosphere.
Remarking on the importance of the core to surface geological structures, MESSENGER Principal Investigator Sean Solomon, at the Carnegie Institution of Washington, said: “The dominant tectonic landforms on Mercury, including areas imaged for the first time by MESSENGER, are features called lobate scarps, huge cliffs that mark the tops of crustal faults that formed during the contraction of the surrounding area. They tell us how important the cooling core has been to the evolution of the surface. After the end of the period of heavy bombardment, cooling of the planet’s core not only fuels the magnetic dynamo, it also led to contraction of the entire planet. And the data from the flyby indicate that the total contraction is a least one third greater than we previously thought.”
“When you look at the planet in the sky, it looks like a simple point of light,” remarked MESSENGER Project Scientist Ralph McNutt, of APL. “But when you experience Mercury close-up through all of MESSENGER’s ‘senses’ seeing it at different wavelengths, feeling its magnetic properties, and touching its surface features and energetic particles, you perceive a complex system and not just a ball of rock and metal. We are all surprised by how active that planet is and at the dynamic interrelationships among its core, surface, exosphere, and magnetosphere.”
“It’s remarkable that this rich lode of data came from two days of imaging, just 30 minutes of sampling the planet’s magnetosphere and exosphere, and less than ten minutes carrying out altimetry and collecting other data near the time of its closest approach 125 miles (200 kilometers) to the surface,” offered Solomon. “MESSENGER’s first flyby was a huge success, both in keeping us on target for the rest of our journey and in advancing our progress toward answering the science questions that have motivated this mission.”
Additional information is available online at http://messenger.jhuapl.edu/mer_flyby1.html. For copies of the papers contact AAAS SciPak at 202-326-6440 or [email protected]
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, 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.

Last edited by Notebook; 07-03-2008 at 09:52 PM. Reason: Update of. content
Notebook is offline   Reply With Quote
Old 08-04-2008, 08:39 PM   #4
Notebook
Donator
 
Notebook's Avatar


Default

Sharing the Wealth: MESSENGER Team Delivers Mercury Flyby 1 Data to Planetary Data System

Data from MESSENGER’s first flyby of Mercury have been released to the public by the Planetary Data System (PDS), an organization that archives and distributes all of NASA’s planetary mission data.

“This delivery, while not the first for the MESSENGER mission, represents a significant milestone,” says MESSENGER Mission Archive Coordinator Alan Mick, of the Johns Hopkins University Applied Physics Laboratory. “We had delivered data from MESSENGER to the PDS before, but not Mercury data,” he says. “This delivery was particularly significant the first MESSENGER flyby of Mercury was mankind’s return to this planet after an absence of over three decades. In this one flyby we imaged previously unseen areas of Mercury’s surface, greatly improved the resolution in areas already covered, and made observations of a kind that had never been made before.”

Calibrated data from three of the probe’s science instruments — the Magnetometer (MAG), the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), and the Mercury Dual Imaging System (MDIS) — are included in this release. “The science results from these instruments have already shed light on questions about Mercury that have lingered for more than three decades,” says MESSENGER Project Scientist Ralph McNutt of APL.

For instance, analyses of data from MDIS have shown that volcanoes were involved in plains formation, and MAG results confirm that the planet’s magnetic field is actively produced in the planet’s core and is not a frozen relic. The MASCS instrument has provided new insights into the extent and complexity of the planet’s tenuous exosphere. “The availability of these data via PDS will allow scientists around the world to study the data and begin making even more connections and discoveries,” McNutt adds.

Since the mid-1990s, NASA has required all of its planetary missions to archive data in the PDS, an active archive that makes available well-documented, peer-reviewed data to the research community. “An essential element of the implementation of NASA missions is the dissemination of collected data to the science community at large,” explains Marilyn Lindstrom, NASAProgram Scientist for MESSENGER. “It’s critical to maintain a planetary data archive that will withstand the test of time so that future generations of scientists can access, understand, and use pre-existing planetary data.”

The PDS includes eight university/research center science teams, called discipline nodes, each of which specializes in specific areas of planetary data. The contributions from these nodes provide a data-rich source for scientists, researchers, and developers. Steven Joy of the University of California, Los Angeles, is MESSENGER’s PDS liaison. His challenge was to coordinate the efforts of the nodes responsible for validating the various datasets before they could be released. “The PDS validation process needs to be comprehensive and unforgiving to ensure that only high-quality, well-documented data are released for use by the science community,” Joy says. “The data archives do not need to be perfect, but they do need to be documented well enough that future users, unfamiliar with how the data were acquired, can understand the data and apply them to new problems.”

The “formal” public release makes mission data available for several applications, including the MESSENGER Mercury flyby visualization tool, available online at http://messenger.jhuapl.edu/encountersactual/. “The tool now includes actual, unprocessed images from the narrow-angle and wide-angle cameras, taken during the January flyby,” says APL’s James McAdams, who designed MESSENGER’s trajectory. “Viewers will see the same images that told the team that the cameras were not only on target, but were revealing Mercury as it had never been seen before.”

In addition, the “Science on a Sphere” exhibit at NASA’s Goddard Space Flight Center’s Visitor Center has now incorporated MESSENGER images into its collection of Solar System displays. This exhibit utilizes four video projectors to display three-dimensional data onto the surface of a six-foot, suspended sphere. “It’s a unique opportunity to project high-resolution NASA data for educational purposes,” notes MESSENGER Education and Public Outreach Project Manager Stephanie Stockman.

MESSENGER Principal Investigator Sean Solomon says it took high level of dedication for the team to pull this off. “Many members of the MESSENGER team devoted long hours and weekends to ensure that the project met the goal of releasing all of our Mercury data six months after the flyby. We are delighted to share these historic data with the scientific community and the public, and we hope that their availability will foster interest everywhere in the mysteries of the Sun’s closest planetary neighbor.”



Happy Anniversary MESSENGER!


It’s been four years since MESSENGER was launched atop a Delta II rocket on August 3, 2004, and they have been busy years. Since it began its odyssey, the spacecraft has travelled 4.33 billion kilometers (2.69 billion miles) relative to the Sun. It has executed four planetary flybys (one of Earth on August 2, 2005; two of Venus, on October 24, 2006, and June 5, 2007; and one of Mercury, on January 14, 2008), three deep-space propulsive maneuvers, and 15 smaller trajectory-correction maneuvers. Up next are two more passes by Mercury (October 6, 2008, and September 29, 2009) and then on March 18, 2011, MESSENGER will become the first spacecraft to enter into orbit around 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.
Notebook is offline   Reply With Quote
Old 09-06-2008, 08:26 AM   #5
Notebook
Donator
 
Notebook's Avatar


Default


MESSENGER Mission News
September 5, 2008
http://messenger.jhuapl.edu


MESSENGER Sails on Sun’s Fire for Second Flyby of Mercury

On September 4, the MESSENGER team announced that it would not need to implement a scheduled maneuver to adjust the probe’s trajectory. This is the fourth time this year that such a maneuver has been called off. The reason? A recently implemented navigational technique that makes use of solar-radiation pressure (SRP) to guide the probe has been extremely successful at maintaining MESSENGER on a trajectory that will carry it over the cratered surface of Mercury for a second time on October 6.


SRP is small and decreases by the square of the distance away from the Sun. But, unlike rockets, so-called solar sailing requires no fuel. And although SRP’s thrust is small, it will continue as long as the Sun is shining and the “sail” is deployed, providing a continuous acceleration source for the probe.

MESSENGER’s mission designers and its guidance and control team at the Applied Physics Laboratory in Laurel, Md., along with the navigation team, at KinetX, Inc., in Simi Valley, Calif., once viewed SRP as something of a challenge to overcome, particularly for the critical gravity-assist flybys – one of Earth, two of Venus, and three of Mercury – that the spacecraft would be executing to position it for Mercury orbit insertion in 2011.

“Because of the changing proximity to the Sun during MESSENGER’s cruise phase, the SRP varies from one to 11 times the value experienced at Earth,” explains APL’s Daniel J. O’Shaughnessy, MESSENGER’s Guidance and Control Lead Engineer. This variation in magnitude, as well as the attitude-dependent direction of the resulting disturbance force and torque, presents a significant challenge to mission designers and the guidance and control team, he says.

“The Mercury flybys are designed to take the probe within approximately 200 kilometers of the planet, so precision targeting is absolutely critical,” O’Shaughnessy says. Fly too low and the probe could crash into the planet. Fly too far away and MESSENGER might have to use its reserve fuel to correct for the acceleration loss. Either way, getting off target could jeopardize the mission.

SRP was seen as an impediment to precise targeting, until the first Mercury flyby in January 2008. About 26 days before that historic event, MESSENGER fired its thrusters to fine-tune its trajectory and aim for the 200-kilometer-altitude flyby point. Prior to the maneuver, the probe was on a course to miss the flyby aim point by more than 2,000 kilometers.

After the maneuver, the probe was still about 9.5 kilometers off from its target. “We still had one more opportunity for another trajectory-correction maneuver four days before the flyby, but we were able to skip it by solar sailing the spacecraft closer to the intended aim point,” explains APL’s Jim McAdams, who designed MESSENGER's trajectory.

Three days earlier than originally planned, the team tilted MESSENGER’s solar panels an extra 20 degrees away from the Sun. The resulting change in solar-array orientation moved the flyby altitude very close to the target aim point. Ultimately, MESSENGER missed its target altitude by only 1.4 kilometers. This targeting was “spectacular,” McAdams says.

The MESSENGER team has planned a more extensive use of this technique for the second Mercury flyby. “We’ve developed a process to use the SRP force as a control for the trajectory,” explains O’Shaughnessy. Using the knowledge developed from the first flyby, the team has developed a carefully planned sequence of probe-body attitude and solar-array orientations that, if all goes according to plan, should reduce the number of trajectory correction maneuvers needed in the future.

According to NASA, the only other visitor to Mercury used solar sailing. In 1974, when the Mariner 10 spacecraft ran low on attitude-control gas, its engineers angled the spacecraft’s solar arrays into the Sun and used solar radiation pressure for attitude control, and it worked. But MESSENGER’s use of the technique represents the first time that a spacecraft has successfully used solar sailing as a propulsion-free trajectory control method for the targeting of planetary flybys.


MESSENGER Team Member Highlight

While the scientists on the MESSENGER team decided what features to image, and the guidance and control team calculated the pointing of the instrument, Nori Laslo – at 29 one of the youngest members on the team – pieced together the commands to tell the camera precisely what to do. Read more about Laslo in the latest MESSENGER Team Highlight, available online at http://messenger.jhuapl.edu/who_we_are/member_focus.html.


Mercury Does a Sunset Tango with Mars and Venus in September

Sky watchers using binoculars and scanning the horizon about 15 to 30 minutes after sunset on September 7 will see a Venus-Mercury-Mars grouping that looks like an isosceles triangle, with the Mars-Mercury and Mars-Venus sides measuring about 2.5 degrees in length and the Mercury-Venus side about 4 degrees. About 10 degrees to the upper left of the triangle will be Spica, the brightest star of the constellation Virgo.

On September 18, Venus, Mercury, and Mars will form an equilateral triangle, whose sides are 4 degrees in length. And Spica will become a part of this arrangement, sitting a few degrees to the left of the triangle. Mercury will remain in the evening sky until October 6, and then reappear on November 25.



One Month to Go until Second Flyby of Mercury!

With just 30 days until MESSENGER’s second encounter with Mercury, the spacecraft remains safe and healthy, with all systems operating nominally. All instruments are on except for the Mercury Laser Altimeter (MLA), which will be powered on September 25 and configured for the encounter. “The final command load for the upcoming flyby is now complete, has been reviewed by the team, and is being tested on the hardware simulator,” says APL’s Peter Bedini, MESSENGER’s project manager. “A successful simulation will represent the passing of the last major milestone in the encounter preparations.”

MESSENGER is about 55.95 million miles (90.04 million kilometers) from the Sun and 87.55 million miles (140.9 million kilometers) from Earth. At that distance, a signal from Earth reaches the spacecraft in 7.8 minutes. The spacecraft is moving around the Sun at 77.5 million miles (124.7 kilometers) per hour.


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.


Notebook is offline   Reply With Quote
Old 09-06-2008, 08:41 AM   #6
FordPrefect
Donator
 
FordPrefect's Avatar

Default

Quote:
Originally Posted by Notebook View Post
 
...
The spacecraft is moving around the Sun at 77.5 million miles (124.7 kilometers) per hour.

...uhhmm, this doesn't sound right. Seems like they mixed up the numbers there greatly!

Thanks Notebook for the heads-up!
FordPrefect is offline   Reply With Quote
Old 09-06-2008, 09:06 AM   #7
Notebook
Donator
 
Notebook's Avatar


Default

Just had a look at

http://messenger.jhuapl.edu/whereis/index.php

and the current range to Earth is given as 87.918 Million Miles. So that agrees with the distance in the article. Can't find any info about the velocity though.

N.
Notebook is offline   Reply With Quote
Old 09-12-2008, 08:20 PM   #8
Notebook
Donator
 
Notebook's Avatar


Default

MESSENGER Mission News
September 12, 2008
http://messenger.jhuapl.edu



MESSENGER Finalizes Plans for Its Second Look at Mercury

It is now only slightly more than three weeks before the MESSENGER spacecraft flies by Mercury for the second time. At 4:40 a.m. ET on October 6, the craft will speed by the planet, passing within 125 miles (200 kilometers) and gaining a gravity assist that will tighten its orbit and keep it on its course to pass the planet one last time next year before becoming the first spacecraft ever to orbit Mercury, beginning in 2011.

A comprehensive set of observations of Mercury and its environment has been designed for this upcoming encounter – deploying all seven of the science payload instruments, in addition to the telecommunications system – to continue the investigations begun during the first encounter with Mercury last January.

Over the last six months, engineers have been building the software commands needed to implement these observations into one single sequence that will be loaded to the spacecraft to run automatically during the encounter. The development of this sequence included several levels of review and testing as it matured. Today, engineers successfully completed the final testing of the commands on the hardware simulator, and on September 29, engineers will send MESSENGER instructions on what observations to perform at each point along the flyby trajectory.

As MESSENGER flew by Mercury on January 14, its instruments imaged 20% of Mercury’s surface not previously seen by spacecraft. The spacecraft made measurements of the planet’s magnetic field, exosphere and sodium tail, surface color and composition, and gravitational field. On its second visit, MESSENGER will image an additional 30% of the surface never before seen by spacecraft.

“MESSENGER’s first flyby of Mercury produced many surprises,” offered MESSENGER Principal Investigator Sean Solomon. “The second flyby will bring us close to the opposite side of the planet from the one we visited in January, and the surface we will view at close range for the first time is larger in area than South America. The only safe prediction at this stage of exploring the innermost planet is that we will make new discoveries.”


Mercury – in 3D!

This graphic shows a portion of the fault scarp Beagle Rupes cutting through the highly elliptical crater Sveinsdóttir in a three-dimensional (3D) representation. Standard 3D glasses (which can be assembled at home), with a red filter in front of the left eye and a blue filter in front of the right one, can be used to view this picture. By combining information from multiple images of the same portion of Mercury's surface taken under different viewing angles, the topography of the surface was determined. A high-resolution image was then overlaid on the topography map, resulting in this 3D image.

More than 80 MESSENGER images were used to create this 3D view of Mercury’s surface. As the MESSENGER mission continues, many more images will be acquired, and these additional images will provide views of Mercury's surface from a variety of illumination conditions and viewing geometries. These myriad views, anchored by topographic profiles to be acquired by MESSENGER’s laser altimeter, will enable large portions of the surface of Mercury to be studied in 3D.



Stat Corner

MESSENGER is about 51.8 million miles (83.4 million kilometers) from the Sun and 81.5
million miles (131.2 million kilometers) from Earth. At that distance, a signal from Earth reaches the spacecraft in 7.3 minutes. The spacecraft is moving around the Sun at 84,744.7 miles (136,383.4 kilometers) per hour.



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.


To Ford Prefect above, looks like you are correct, and they got the velocity out by a 10^3.

N.
Notebook is offline   Reply With Quote
Old 09-30-2008, 06:01 AM   #9
Notebook
Donator
 
Notebook's Avatar


Default


MESSENGER Mission News
September 29, 2008
http://messenger.jhuapl.edu




MLA Ready to Range to Mercury’s Surface

One week from today, the MESSENGER spacecraft will fly by Mercury for the second time this year. As part of the final preparations for this encounter, the Mercury Laser Altimeter (MLA) has been powered on after having been off since shortly after the first flyby at the beginning of the year. The entire MESSENGER science payload is now powered and configured to collect data during next week’s encounter.

“Right after the January flyby, the MLA completed passive observations of Mercury, without the laser firing, as a calibration,” explained MLA Instrument Scientist Olivier Barnouin-Jha of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.
“At that point it was switched off, and it has remained off since that time,”

During MESSENGER’s first Mercury encounter, the MLA provided the first direct measurements of the topography of Mercury from spacecraft. The results provide evidence for a complex geologic history and indicate that Mercury’s craters are shallower than those on the Moon at a given crater diameter, as expected because of the higher surface gravity.

“Unlike the topographic data obtained during the first flyby, which were of terrain for which we have no space-based imaging, some of the area to which MLA will range during this second encounter was imaged by the Mercury Dual Imaging System (MDIS) during the first Mercury flyby,” Barnouin-Jha said. Moreover, terrain sampled by MLA during the first flyby will in turn be imaged by MDIS during this visit.

“So this second flyby will allow the first inter-comparison between the topographic observations and high-resolution spacecraft images,” he added.




Imaging Plans for MESSENGER’s Second Mercury Flyby

Mariner 10, the only spacecraft to visit Mercury prior to the MESSENGER mission, imaged about 45% of the planet’s surface. In January, MESSENGER’s Mercury Dual Imaging System (MDIS) captured an additional 21% of Mercury’s surface. During its upcoming encounter with Mercury, the 1,287 planned MDIS images will cover much of the remaining portion of Mercury’s surface not yet seen by spacecraft. A map of Mercury’s surface with images from Mariner 10 overlaid by mosaics by the MDIS narrow-angle camera (NAC) acquired during MESSENGER’s first Mercury flyby is available online at http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=205.

MESSENGER’s first flyby of Mercury covered two general areas of Mercury surface: the crescent view of Mercury seen as the spacecraft approached the planet and the fuller view of Mercury acquired as the spacecraft departed. Similarly, Mercury will appear as a thin crescent during the inbound portion of MESSENGER’s second Mercury flyby and as a nearly full disk during the outbound portion of the encounter. The areas of the surface that will be imaged by the NAC are shaded in purple in the figure. One week from today, as may be seen from the figure, spacecraft imaging of Mercury’s surface will be nearly global in coverage for the first time.




Experience MESSENGER’s Second Mercury Flyby Virtually

See Mercury through the “eyes” of MESSENGER’s imagers with the Mercury Flyby Visualization Tool, now available at http://messenger.jhuapl.edu/encountersm2/. This updated Web feature offers a unique opportunity to see simulated views of Mercury from MESSENGER’s perspective, during approach, flyby, and departure, or in real-time (as the observations actually occur).

This tool combines the best available image map of Mercury’s surface with observation sequences for the Mercury Dual Imaging System (MDIS), Mercury Atmospheric and Surface Composition Spectrometer (MASCS), and Mercury Laser Altimeter (MLA). The map of Mercury’s surface combines Earth-based low-resolution radar images from the Arecibo Observatory in Puerto Rico, high-resolution image mosaics from the Mariner 10 spacecraft flybys of Mercury in 1974 and 1975, and images from MESSENGER's first flyby of Mercury on January 14, 2008.

There are many helpful tips available on the pages of this visualization tool. Pointing and clicking on any color bar will display the projection of each completed image mosaic on Mercury or show the end of the active MLA or MASCS observation. Information accompanying each simulated image includes the latitude and longitude of the point at the center of each image, the resolution in meters (or kilometers when farther from the planet) per pixel (picture element) at the image center, the altitude (how far the spacecraft is above Mercury's surface), and the time relative to closest approach.





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.



Notebook is offline   Reply With Quote
Old 10-03-2008, 07:11 PM   #10
Notebook
Donator
 
Notebook's Avatar


Default


MESSENGER Mission News
October 3, 2008
http://messenger.jhuapl.edu


MESSENGER Beams Back First Approach Images of Mercury

MESSENGER mission operators at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., have received the first optical navigation images from the spacecraft. “We will be taking seven additional sets over the next three days as the spacecraft approaches the planet,” said APL’s Eric Finnegan, the Mission Systems Engineer.

Optical navigation is commonly used to tie the position of a spacecraft to the position of a target body to ensure a safe and well-positioned flyby, particularly when the position of the target body is uncertain or if the navigation process has not been validated in flight. “During the first encounter with Mercury, both of these issues were of concern to mission planners,” Finnegan explained. “However, following the highly accurate flyby in January, the necessity of these images for critical trajectory planning was removed.”


“For successful optical navigation, we need to see the target body in the same image sequence as the background star field,” said MESSENGER’s Navigation Team Chief Ken Williams of KinetX, Inc. “Stars are far away, so to us, it appears that their positions are fixed in space. By comparing where Mercury is in the field-of-view with the stars visible behind it, and by controlling where the camera is pointing, we can estimate the position of the spacecraft.”

The Mercury Dual Imaging System (MDIS) instrument consists of two imagers, a wide-angle camera (WAC) with a 10.5º field of view, and a narrow-angle camera (NAC), with a 1.5º field of view. These imagers are always pointed at the same place, and the NAC footprint falls in the center of the WAC footprint. The WAC has a filter specially designed for imaging stars, most of which are so faint that long (up to 10-second) exposures are required.

The MESSENGER team employs both cameras for optical navigation, taking a star image with the WAC, and then quickly switching to the NAC for an image of the planet limb. Because the images are taken within seconds of each other, they can be used to see where the planet is compared with the star field.


The navigation images snapped during this flyby will also help the team plot MESSENGER’s yearlong orbital survey of Mercury, which begins in March 2011. MESSENGER will fly very close to the surface of Mercury—within 200 kilometers (124 miles)—during the October 6 flyby, as it did in January. However, during this encounter, the navigation team will rely only on radiometric tracking data during closest approach.


As the flyby continues toward closest approach, additional information and features will be available online at http://messenger.jhuapl.edu/mer_flyby2.html, so check back frequently. Following the flyby, be sure to check back to see the latest released images and science results!


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.

Notebook is offline   Reply With Quote
Old 10-04-2008, 08:10 PM   #11
Notebook
Donator
 
Notebook's Avatar


Default

MESSENGER Mission News
October 4, 2008
http://messenger.jhuapl.edu


Closing in on Mercury

If you look at our “Where Is MESSENGER?” page, which displays the spacecraft's trajectory status, you'll see that we're right on Mercury's doorstep. MESSENGER's mission design and navigation teams met today at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., to discuss the spacecraft's current trajectory to determine if a last-minute trajectory-correction maneuver would be needed.

Early this morning, the navigation team delivered the final ephemeris update for the spacecraft prior to the flyby,” said APL’s Eric Finnegan, the MESSENGER Mission Systems Engineer. “The data indicate that the last solar sailing attitude alternation implemented between Tuesday and Wednesday was a complete success. The current position estimate places the spacecraft within approximately 800 meters of the target! This is a phenomenal achievement for both the navigation and guidance and control teams.”

“The operations team has confirmed that the core Mercury command load sequence was onboard the spacecraft, and all subsystems and instruments are operating nominally,” Finnegan said. With less than two days to the flyby, MESSENGER is on target to encounter Mercury at an altitude of 200 kilometers (124 miles) on Monday, October 6, at approximately 4:41 a.m. EDT.

Over the next two days, the spacecraft will continue to gather optical navigation images approximately every eight hours, while the operations team monitors the spacecraft. You can view the latest one online at http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=207.

The entire operations and engineering teams will gather in the operations center at APL on Sunday to make one last assessment of the spacecraft before the core encounter sequence begins, rotating the probe away from the Earth to view once again the closest planet to the Sun, revealing terrain never before seen by spacecraft!



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.
Notebook is offline   Reply With Quote
Old 10-06-2008, 04:35 AM   #12
Notebook
Donator
 
Notebook's Avatar


Default

MESSENGER Mission News
October 5, 2008
http://messenger.jhuapl.edu


MESSENGER Instruments Take Aim

MESSENGER’s engineering and operations teams convened at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., this afternoon to confirm the health and readiness of the spacecraft. “All spacecraft sub-systems and instruments reported nominal operations indicating that MESSENGER is ready for its second encounter with Mercury,” said MESSENGER Systems Engineer Eric Finnegan of APL.

At 6:05 p.m. EDT the last bits of data from the spacecraft were received as it transitioned from high-gain downlink to beacon-only operations, and the spacecraft reoriented itself to begin science operations. Before turning away, however, the spacecraft returned a set of optical navigation images (available online at http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=212) of the terrain not yet seen up-close by any spacecraft to whet our appetite regarding the discoveries to come.

For the next 10 hours or so, the spacecraft will take repetitive scans through Mercury’s comet-like anti-sunward tail, pausing now and then to take a color image and a high-resolution mosaic of Mercury with the Mercury Dual Imaging System instrument.

“The operations team is now preparing for the period of time about an hour prior to closest approach [at 4:40:21 a.m. EDT], when we will be transitioning our support from the Canberra ground station to the Madrid ground station that will capture the flyby,” Finnegan said. “High-gain communications with the spacecraft will be re-establishedon Tuesday at 1:14 a.m. EDT at approximately 52 kilobits per second, and playback of the data stored in the solid-state recorder will start approximately 30 minutes later.”

“MESSENGER is now on its own. The MESSENGER team is confident that our probe will carry out the full flyby command sequence, which was developed and thoroughly tested by the many dedicated engineers and scientists on the MESSENGER flight team,” said MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. “We all look forward with excitement to the flyby data set that we will start to glimpse Tuesday morning. We’ll be seeing at close range, for the first time, a region of Mercury larger in area than South America. Discoveries are just hours away.”


As the flyby continues toward closest approach, additional information and features will be available online at http://messenger.jhuapl.edu/mer_flyby2.html, so check back frequently. Following the flyby, be sure to check back to see the latest released images and science results!



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.

Notebook is offline   Reply With Quote
Old 10-06-2008, 08:17 AM   #13
SiberianTiger
News Sifter
 
SiberianTiger's Avatar

Default

The Messenger has swung by Mercury for the second time!

BTW, a very interesting fly-by mission chart by JPL here:

SiberianTiger is offline   Reply With Quote
Old 10-07-2008, 05:26 PM   #14
Notebook
Donator
 
Notebook's Avatar


Default


MESSENGER Mission News
October 6, 2008
http://messenger.jhuapl.edu


MESSENGER Flyby of Mercury

At a little after 4:40 a.m. EDT, MESSENGER skimmed 200 kilometers (124 miles) above the surface of Mercury in the second of three flybys of the planet. Initial indications from the radio signals indicate that the spacecraft continues to operate nominally. The spacecraft is now collecting images and other scientific measurements from the planet as it departs Mercury from the illuminated side, filling in the details of much of Mercury’s surface not previously viewed by spacecraft.

Tomorrow at 1:14 a.m. EDT, the spacecraft will turn its high-gain antenna back toward Earth to start down-linking the data stored onboard. The first pictures from the flyby will be released around 10:00 a.m. on October 7, 2008. Additional information and features from this encounter will be available online at http://messenger.jhuapl.edu/mer_flyby2.html. Be sure to check back frequently to see the latest released images and science results!

From Mariner 10 to MESSENGER

On Wednesday, October 8, 2008, MESSENGER Science Team member Mark Robinson, from Arizona State University, will talk about what we’ve learned about Mercury in the last three decades and release new pictures from MESSENGER’s second flyby of Mercury. The event, to be held at the Kossiakoff Center on the campus of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., will begin at 4 p.m. To RSVP, go online to http://messenger.jhuapl.edu/RSVP/.



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.



-----Posted Added-----



MESSENGER Mission News
October 7, 2008
http://messenger.jhuapl.edu


MESSENGER Reveals Mercury as Never Seen Before

When Mariner 10 flew past Mercury three times in 1974 and 1975, the probe imaged less than half the planet. In January, during MESSENGER’s first flyby, its cameras returned images of about 20 percent of the planet’s surface missed by Mariner 10. Yesterday, at 4:40 am EDT, MESSENGER successfully completed its second flyby of Mercury, and its cameras captured 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.

“The MESSENGER team is extremely pleased by the superb performance of the spacecraft and the payload,” said MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. “We are now on the correct trajectory for eventual insertion into orbit around Mercury, and all of our instruments returned data as planned from the side of the planet opposite to the one we viewed during our first flyby. When these data have been digested and compared, we will have a global perspective of Mercury for the first time.”

Today, at about 1:50 a.m. EDT, MESENGER turned to Earth and began transmitting data gathered during its second Mercury encounter. This spectacular image – one of the first to be returned – was snapped by the Wide Angle Camera (WAC), part of the Mercury Dual Imaging System (MDIS) instrument, about 90 minutes after MESSENGER's closest approach to Mercury, when the spacecraft was at a distance of about 27,000 kilometers (about 17,000 miles).

The bright crater just south of the center of the image is Kuiper, identified on images from the Mariner 10 mission in the 1970s. For most of the terrain east of Kuiper, toward the edge of the planet, the departing images are the first spacecraft views of that portion of Mercury’s surface. A striking characteristic of this newly imaged area is the large pattern of rays that extend from the northern region of Mercury to regions south of Kuiper.

This WAC image is one in a sequence of 55: a five-frame mosaic with each frame in the mosaic acquired in all 11 of the WAC filters. This portion of Mercury’s surface was previously imaged under different lighting conditions by Mariner 10, but this new MESSENGER image mosaic is the highest-resolution color imaging ever acquired of any portion of Mercury’s surface.

Additionally, some of the images in this mosaic overlap with flyby data acquired by the Mercury Atmospheric and Surface Composition Spectrometer and Mercury Laser Altimeter instruments, resulting in the first time that these three instruments have gathered data of the same area of Mercury. The combination of these three datasets will enable unprecedented studies of this region of Mercury’s surface.

This image, acquired about 89 minutes before the craft’s closest approach to Mercury, resembles the optical navigation images taken leading up to the flyby. The resolution of this image is somewhat better than that obtained by the final optical navigation image set, and the surface visible is newly imaged terrain that was not previously seen by either Mariner 10 or during MESSENGER’s first flyby.

However, the added resolution is not the main scientific advancement that will be provided by this image. This WAC image is one of 11 viewed through different narrow-band color filters, the set of which will enable detailed color studies of this newly imaged area. In addition, the Narrow Angle Camera (NAC) acquired a high-resolution mosaic of most of this thin crescent view of Mercury at a resolution better than 0.5 kilometers/pixel (0.3 miles/pixel) that will enable the MESSENGER team to explore this newly imaged region of Mercury’s surface in more detail.

About 58 minutes before MESSENGER’s closest approach to Mercury, the NAC captured this close-up image of a portion of Mercury’s surface imaged by spacecraft for the first time. It is one of 44 in a high-resolution NAC mosaic taken of the approaching crescent-shaped Mercury, as seen at lower resolution in the optical navigation images and the approach WAC color image set.

As the MESSENGER team is busy examining this newly obtained view, data from the flyby continue to stream down to Earth, including higher resolution close-up images of this previously unseen terrain.Collectively, these images and measurements made by other MESSENGER instruments will soon provide a broad range of information for understanding the formation and geologic history of the innermost planet.



Additional information and features from this encounter will be available online at http://messenger.jhuapl.edu/mer_flyby2.html, so check back frequently to see the latest released images and science results!

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.

Notebook is offline   Reply With Quote
Old 10-07-2008, 06:40 PM   #15
astrosammy
Dash!
 
astrosammy's Avatar

Default

A little question about the image:

Is it a true color image? Because all these MESSENGER images look much different to what I see in Orbiter and the old Mariner 10 images:
astrosammy is offline   Reply With Quote
Reply

  Orbiter-Forum > Far Side of the Moon > Spaceflight News


Thread Tools

Posting Rules
BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
Forum Jump


All times are GMT. The time now is 12:18 AM.

Quick Links Need Help?


About Us | Rules & Guidelines | TOS Policy | Privacy Policy

Orbiter-Forum is hosted at Orbithangar.com
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Copyright ©2007 - 2017, Orbiter-Forum.com. All rights reserved.