posted February 13, 2004 04:54 PM               

I've also been a long time fan of the Mission Manager. He was responsible for cooking up the first mission to a comet (Giacobini-Zinner). He recycled a spacecraft and cranked it up to speed by repeated flybys of the earth and the moon.

My hero, Dr. Robert W. Farquhar.

He gave a talk at a public lecture I arranged a few years ago. His one demand was that he pick the restaurant for the dinner before the talk.

posted September 02, 2005 09:20 AM               

While this clip is pretty cool in its own right, in the context of the MESSENGER flyby of Earth, it just drives home how spectacular our homeworld really is.

posted January 08, 2008 12:33 AM               

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MESSENGER Only One Week from Mercury

MESSENGER's mid-December trajectory correction maneuver (TCM) went so well that the mission's design and navigation teams have decided that a TCM scheduled for January 10 will not be needed.

"Cancellation of this maneuver is a demonstration of the near-perfect execution of TCM-19 just prior to the start of the holiday season," says Mission Systems Engineer Eric Finnegan of the Johns Hopkins University Applied Physics Laboratory in Laurel, Md.

On January 9, MESSENGER's Mercury Dual Imaging System cameras will begin gathering pictures of Mercury as the probe zeros in on the planet. "With just one week to go before the flyby, the spacecraft is on target to encounter the planet at an altitude of 202 kilometers," Finnegan says. "All subsystems and instruments are operating nominally and configured for the start of the flyby sequence, except for the Mercury Laser Altimeter and part of the Gamma-Ray Spectrometer, which we'll turn on just before the flyby."

Over the next week, the team will make final flyby preparations and upload the final command sequences for the encounter.

"We are about to visit Mercury for the first time in more than 30 years, and we can't wait," says MESSENGER Principal Investigator Sean Solomon of the Carnegie Institution of Washington. "In addition to providing the critical gravity assist that will move MESSENGER along its path toward Mercury orbit insertion in March 2011, this flyby will let us see parts of Mercury never before viewed by spacecraft. We'll be making close-in observations of the composition of Mercury's surface and atmosphere, and we'll be probing deeper into the planet's magnetosphere than we've ever been. We expect many surprises."

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posted January 10, 2008 12:47 PM               

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NASA Spacecraft to Make Historic Flyby of Mercury

On Monday, Jan. 14, a pioneering NASA spacecraft will be the first to visit Mercury in almost 33 years when it soars over the planet to explore and snap close-up images of never-before-seen terrain. These findings could open new theories and answer old questions in the study of the solar system.

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, called MESSENGER, is the first mission sent to orbit the planet closest to our sun. Before that orbit begins in 2011, the probe will make three flights past the small planet, skimming as close as 124 miles above Mercury's cratered, rocky surface. MESSENGER's cameras and other sophisticated, high-technology instruments will collect more than 1,200 images and make other observations during this approach, encounter and departure. It will make the first up-close measurements since Mariner 10 spacecraft's third and final flyby on March 16, 1975. When Mariner 10 flew by Mercury in the mid-1970s, it surveyed only one hemisphere.

"This is raw scientific exploration and the suspense is building by the day," said Alan Stern, associate administrator for NASA's Science Mission Directorate, Washington. "What will MESSENGER see? Monday will tell the tale."

This encounter will provide a critical gravity assist needed to keep the spacecraft on track for its March 2011 orbit insertion, beginning an unprecedented yearlong study of Mercury. The flyby also will gather essential data for mission planning.

"During this flyby we will begin to image the hemisphere that has never been seen by a spacecraft and Mercury at resolutions better than those acquired by Mariner 10," said Sean C. Solomon, MESSENGER principal investigator, Carnegie Institution of Washington. "Images will be in a number of different color filters so that we can start to get an idea of the composition of the surface."

One site of great interest is the Caloris basin, an impact crater about 800 miles in diameter, which is one of the largest impact basins in the solar system.

"Caloris is huge, about a quarter of the diameter of Mercury, with rings of mountains within it that are up to two miles high," said Louise Prockter, the instrument scientist for the Mercury Dual Imaging System at the Johns Hopkins University Applied Physics Laboratory in Laurel. "Mariner 10 saw a little less than half of the basin. During this first flyby, we will image the other side."

MESSENGER's instruments will provide the first spacecraft measurements of the mineralogical and chemical composition of Mercury's surface. It also will study the global magnetic field and improve our knowledge of the gravity field from the Mariner 10 flyby. The long-wavelength components of the gravity field provide key information about the planet's internal structure, particularly the size of Mercury's core.

The flyby will provide an opportunity to examine Mercury's environment in unique ways, not possible once the spacecraft begins orbiting the planet. The flyby also will map Mercury's tenuous atmosphere with ultraviolet observations and document the energetic particle and plasma of Mercury's magnetosphere. In addition, the flyby trajectory will enable unique particle and plasma measurements of the magnetic tail that sweeps behind Mercury.

Launched Aug. 3, 2004, MESSENGER is slightly more than halfway through its 4.9-billion mile journey. It already has flown past Earth once and Venus twice. The spacecraft will use the pull of Mercury's gravity during this month's pass and others in October 2008 and September 2009 to guide it progressively closer to the planet's orbit. Insertion will be accomplished with a fourth Mercury encounter in 2011.

The MESSENGER project is the seventh in NASA's Discovery Program of low-cost, scientifically focused space missions. The Applied Physics Laboratory designed, built and operates the spacecraft and manages the mission for NASA.

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posted January 10, 2008 01:22 PM               

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On January 9, 2008, the MESSENGER spacecraft snapped one of its first images of Mercury at a distance of about 2.7 million kilometers (1.7 million miles) from the planet.

The image was acquired with the Narrow Angle Camera, one half of MESSENGER's Mercury Dual Imaging System (MDIS) instrument. Mercury is about 4880 kilometers (3030 miles) in diameter, and this image has a resolution of about 70 kilometers/pixel (43 miles/pixel).

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posted January 14, 2008 07:30 PM               

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Tomorrow [Tuesday] at noon EST, the spacecraft will turn back towards the Earth to start down-linking the on-board stored data. Measurements of this Doppler signal from the spacecraft will allow improve knowledge of Mercury’s gravity field.

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posted January 15, 2008 10:23 PM               

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MESSENGER's First Look at Mercury’s Previously Unseen Side

When Mariner 10 flew past Mercury three times in 1974 and 1975, the same hemisphere was in sunlight during each encounter. As a consequence, Mariner 10 was able to image less than half the planet. Planetary scientists have wondered for more than 30 years about what spacecraft images might reveal about the hemisphere of Mercury that Mariner 10 never viewed.

On January 14, 2008, the MESSENGER spacecraft observed about half of the hemisphere missed by Mariner 10. This image was snapped by the Wide Angle Camera, part of the Mercury Dual Imaging System (MDIS) instrument, about 80 minutes after MESSENGER's closest approach to Mercury (2:04 pm EST), when the spacecraft was at a distance of about 27,000 kilometers (about 17,000 miles). The image shows features as small as 10 kilometers (6 miles) in size. This image was taken through a filter sensitive to light near the red end of the visible spectrum (750 nm), one of a sequence of images taken through each of MDIS’s 11 filters.

Like the previously mapped portion of Mercury, this hemisphere appears heavily cratered. It also reveals some unique and distinctive features. On the upper right is the giant Caloris basin, including its western portions never before seen by spacecraft. Formed by the impact of a large asteroid or comet, Caloris is one of the largest, and perhaps one of the youngest, basins in the Solar System. The new image shows the complete basin interior and reveals that it is brighter than the surrounding regions and may therefore have a different composition. Darker smooth plains completely surround Caloris, and many unusual dark-rimmed craters are observed inside the basin. Several other multi-ringed basins are seen in this image for the first time. Prominent fault scarps (large ridges) lace the newly viewed region.

Other images obtained during the flyby will reveal surface features in color and in much more detail. Collectively, these images and measurements made by other MESSENGER instruments will soon provide a detailed global view of the surface of Mercury, yielding key information for understanding the formation and geologic history of the innermost planet.

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posted January 16, 2008 01:30 PM               

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As MESSENGER approached Mercury on January 14, 2008, the spacecraft’s Narrow-Angle Camera on the Mercury Dual Imaging System (MDIS) instrument captured this view of the planet’s rugged, cratered landscape illuminated obliquely by the Sun. The large, shadow-filled, double ringed crater to the upper right was glimpsed by Mariner 10 more than three decades ago and named Vivaldi, after the Italian composer. Its outer ring has a diameter of about 200 kilometers (about 125 miles). MESSENGER’s modern camera has revealed detail that was not well seen by Mariner 10, including the broad ancient depression overlapped by the lower-left part of the Vivaldi crater. The MESSENGER science team is in the process of evaluating later images snapped from even closer range showing features on the side of Mercury never seen by Mariner 10. It is already clear that MESSENGER’s superior camera will tell us much that could not be resolved even on the side of Mercury viewed by Mariner’s vidicon camera in the mid-1970s.

This MESSENGER image was taken from a distance of about 18,000 kilometers (11,000 miles), about 56 minutes before the spacecraft's closest encounter with Mercury. It shows a region roughly 500 kilometers (300 miles) across, and craters as small as 1 kilometer (0.6 mile) can be seen in this image.

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posted January 18, 2008 09:53 AM               

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Bob Strom had begun to lose hope.

A veteran of NASA's Mariner 10 mission to Mercury in the 1970s, he was bursting with questions that the Mariner flybys had raised about the little planet but couldn't answer.

"I've been hoping for another Mercury mission for 30 years, practically," said Strom, an expert on impact craters. But for decades, NASA seemed unable to make it happen.

"I really thought... I'd never live to see Mercury again," he said.

But he did.

This week, NASA's Messenger spacecraft whizzed past Mercury and sent back more than 1,200 photos and measurements from the sun's nearest neighbor, and Strom was in the thick of it.

At 74, he is the only member of the old Mariner 10 team serving on the Messenger science team. He has been holed up in the mission's Science Operations Center, at the Johns Hopkins University's Applied Physics Lab near Laurel, marveling over the new data from Mercury.

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posted July 04, 2008 09:51 AM               

NASA Reveals New Discoveries From Mercury

Scientists have argued about the origins of Mercury's smooth plains and the source of its magnetic field for more than 30 years. Now, analyses of data from the January 2008 flyby of the planet by the Mercury Surface, Space Environment, Geochemistry and Ranging (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.

Scientists additionally took their first look at the chemical composition of the planet's surface. 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 Science magazine July 4.

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 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 vents along the margins of the Caloris basin, one of the solar system's youngest impact basins. They also found that Caloris has a much more complicated geologic history than previously believed.

The first altitude measurements from any spacecraft at Mercury also found that craters on the planet are about a factor of two shallower than those on Earth's moon. The measurements also show a complex geologic history for Mercury.

Mercury's core makes up at least 60 percent of its mass, a figure twice as large as any other known terrestrial 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, 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 fueled 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."

The flyby also made the first-ever observations of the ionized particles in Mercury's unique exosphere. The exosphere is an ultrathin atmosphere in which 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.