NASA'S MESSENGER Spacecraft Begins Historic Orbit Around Mercury

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NASA'S MESSENGER Spacecraft Begins Historic Orbit Around Mercury
UNITED STATES - 17 MARCH 2011

WASHINGTON -- NASA's MESSENGER spacecraft successfully achieved orbit around Mercury at approximately 9 p.m. EDT Thursday. This marks the first time a spacecraft has accomplished this engineering and scientific milestone at our solar system's innermost planet.

"This mission will continue to revolutionize our understanding of Mercury during the coming year," said NASA Administrator Charles Bolden, who was at MESSENGER mission control at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., as engineers received telemetry data confirming orbit insertion. "NASA science is rewriting text books. MESSENGER is a great example of how our scientists are innovating to push the envelope of human knowledge."

At 9:10 p.m. EDT, engineers Operations Center, received the anticipated radiometric signals confirming nominal burn shutdown and successful insertion of the MESSENGER probe into orbit around the planet Mercury. NASA's MErcury Surface, Space ENvironment, Geochemistry, and Ranging, or MESSENGER, rotated back to the Earth by 9:45 p.m. EDT, and started transmitting data. Upon review of the data, the engineering and operations teams confirmed the burn executed nominally with all subsystems reporting a clean burn and no logged errors.

MESSENGER's main thruster fired for approximately 15 minutes at 8:45 p.m., slowing the spacecraft by 1,929 miles per hour and easing it into the planned orbit about Mercury. The rendezvous took place about 96 million miles from Earth.

"Achieving Mercury orbit was by far the biggest milestone since MESSENGER was launched more than six and a half years ago," said Peter Bedini, MESSENGER project manager of the Applied Physics Laboratory (APL). "This accomplishment is the fruit of a tremendous amount of labor on the part of the navigation, guidance-and-control, and mission operations teams, who shepherded the spacecraft through its 4.9-billion-mile journey."

For the next several weeks, APL engineers will be focused on ensuring the spacecraft's systems are all working well in Mercury's harsh thermal environment. Starting on March 23, the instruments will be turned on and checked out, and on April 4 the mission's primary science phase will begin.

"Despite its proximity to Earth, the planet Mercury has for decades been comparatively unexplored," said Sean Solomon, MESSENGER principal investigator of the Carnegie Institution of Washington. "For the first time in history, a scientific observatory is in orbit about our solar system's innermost planet. Mercury's secrets, and the implications they hold for the formation and evolution of Earth-like planets, are about to be revealed."

APL designed and built the spacecraft. The lab manages and operates the mission for NASA's Science Mission Directorate in Washington.


Source: NASA

 

[Someoneforyou]

 

[Someoneforyou]

Astronomers are interested in Mercury, the closest planet to the sun, because it is a terrestrial like Earth, not gassy like Jupiter. It is also an extremely difficult place for scientists to explore due to the planet's surface temperature, which would melt lead. There are many such rocky orbs around stars outside our solar system, which means Mercury could offer clues to other worlds as well, NASA said.

Flyby: On October 6, 2008, the Messenger probe successfully completed its second flyby of Mercury, sending reams of data back to Earth

An artist's impression of Messenger orbiting Mercury. Astronomers are interested in Mercury, the closest planet to the sun, because it is a terrestrial like Earth, not gassy like Jupiter

 

[Someoneforyou]

NASA releases historic pictures of Mercury from Messenger craft
UNITED STATES - 30 MARCH 2011

NASA has released the first picture taken of Mercury's surface by the US space agency's orbiting Messenger craft.

"Early this morning... Messenger captured this historic image of Mercury," NASA said. 'This image is the first ever obtained from a spacecraft in orbit about the solar system's innermost planet."

The spacecraft snapped 363 images over the next six hours, and more were expected to be released today in conjunction with an expert press conference to discuss the findings.

The upper part of the image shows an unusual, dark-rayed crater called Debussy, while the lower part reveals a portion of Mercury near its south pole that has never before been witnessed by spacecraft, NASA said.

NASA's Messenger craft - which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging - became the first vehicle to orbit Mercury on March 17.

Messenger was launched more than six years ago, travelling through the inner solar system and embarking on flybys of Earth, Venus and Mercury.

The first NASA craft to study Mercury since the Mariner mission more than three decades ago, Messenger has already been able to return a partial map of the planet's crater-filled surface after just a handful of flybys.

Source: AFP

 

[Someoneforyou]

Northrop Grumman Solar Array Capabilities Enable MESSENGER Probe to Operate in Extreme Temperatures Orbiting Mercury
UNITED STATES - 8 JUNE 2011

Redondo Beach, Calif. - Key technologies and hardware developed by Northrop Grumman Corporation (NYSE:NOC) gave the first spacecraft to orbit Mercury a power system that works to its maximum even in the searing heat that surrounds the planet closest to the sun.

The solar array on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft features advanced triple-junction gallium arsenide solar cells and an electrical harness developed and qualified for this mission by Northrop Grumman Aerospace Systems. The company also perfected a fully robotic welding process to assemble the photovoltaic cells before they were bonded to the solar array panel. The work was done under the pressure of meeting a launch window that was so tight that missing it would have meant a year-long wait until the next launch opportunity.

"When it launched in 2004, MESSENGER was the first Northrop Grumman program to use these advanced solar cells, electrical designs and welding processes that now are the baseline for all our major programs, including the James Webb Space Telescope and the Defense Weather Satellite System," said Tim Frei, vice president, system enhancements and product applications for Northrop Grumman Aerospace Systems. "Our depth of talent and the processes we developed enabled us to perfect the technology needed for spacecraft to perform under very harsh conditions."

Solar array performance is critical - if it fails, so does the mission. Two single-sided solar panels are MESSENGER's main source of electrical power. They are two-thirds mirrors and one-third solar cells. The mirrors reflect the sun's energy and keep the panels cooler. The panels also rotate away from the sun to get the required power and maintain an operating temperature of about 300 F.

Since its launch, MESSENGER has completed one swing past Earth, two Venus flybys and three Mercury flybys. By using the gravity of each planet to gain speed and alter its trajectory, MESSENGER was able to conserve the fuel it will need during its mission orbiting a planet that is only 29 million miles from the sun, about two thirds closer to the sun than Earth. At Mercury's equator, surface temperatures become hot enough to melt lead. The spacecraft's fast, elliptical orbit allows it to approach Mercury, gather data and swing out far into space to cool down.

MESSENGER is a NASA Discovery program spacecraft designed and built by the Johns Hopkins University Applied Physics Laboratory, Laurel, Md. The probe completed a six-and-a-half-year journey prior to its March 17 insertion into orbit around the planet closest to our sun. MESSENGER will orbit 730 times around Mercury for a year.


Source: Northrop Grumman Corporation

 

[Godless-Kafir]

Why does Mercury look a lot like moon!! Is that the moon or mercury?

 

[Someoneforyou]

MESSENGER Provides New Data about Mercury
UNITED STATES - 16 JUNE 2011

After nearly three months in orbit about Mercury, MESSENGER's payload is providing a wealth of new information about the planet closest to the Sun, as well as a few surprises.

The spacecraft entered orbit around Mercury on March 18, 2011 UTC, becoming the first spacecraft ever to do so. Tens of thousands of images of major features on the planet - previously seen only at comparatively low resolution - are now available in sharp focus. Measurements of the chemical composition of Mercury's surface are providing important clues to the origin of the planet and its geological history. Maps of the planet's topography and magnetic field are revealing new clues to Mercury's interior dynamical processes. And scientists now know that bursts of energetic particles in Mercury's magnetosphere are a continuing product of the interaction of Mercury's magnetic field with the solar wind.

This week, MESSENGER completed is first perihelion passage from orbit, its first superior solar conjunction from orbit, and its first orbit-correction maneuver. "Those milestones provide important context to the continuing feast of new observations that MESSENGER has been sending home on nearly a daily basis," offers MESSENGER Principal investigator Sean Solomon of the Carnegie Institution of Washington.

A Surface Revealed in Unprecedented Detail

Among the fascinating features seen in MESSENGER flyby images of Mercury were bright, patchy deposits on some crater floors. Without high-resolution images to obtain a closer look, these features remained a curiosity. New targeted Mercury Dual Imaging System images at up to 10 meters per pixel reveal these patchy deposits to be clusters of rimless, irregular pits varying in size from hundreds of meters to several kilometers. These pits are often surrounded by diffuse halos of higher-reflectance material, and they are found associated with central peaks, peak rings, and rims of craters.

"The etched appearance of these landforms is unlike anything we've seen before on Mercury or the Moon," says Brett Denevi, a staff scientist at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Md., and a member of the MESSENGER imaging team. "We are still debating their origin, but they appear to have a relatively young age and may suggest a more abundant than expected volatile component in Mercury's crust."

Mercury's Surface Composition

The X-ray Spectrometer (XRS) - one of two instruments on MESSENGER designed to measure the abundances of many key elements on Mercury - has made several important discoveries since the orbital mission began. The magnesium/silicon, aluminum/silicon, and calcium/silicon ratios averaged over large areas of the planet's surface show that, unlike the surface of the Moon, Mercury's surface is not dominated by feldspar-rich rocks.

XRS observations have also revealed substantial amounts of sulfur at Mercury's surface, lending support to prior suggestions from ground-based telescopic spectral observations that sulfide minerals are present. This discovery suggests that the original building blocks from which Mercury was assembled may have been less oxidized than those that formed the other terrestrial planets, and it has potentially important implications for understanding the nature of volcanism on Mercury.

Mapping of Mercury's Topography and Magnetic Field

MESSENGER's Mercury Laser Altimeter has been systematically mapping the topography of Mercury's northern hemisphere. After more than two million laser-ranging observations, the planet's large-scale shape and profiles of geological features are both being revealed in high detail. The north polar region of Mercury, for instance, is a broad area of low elevations. The overall range in topographic heights seen to date exceeds 9 kilometers.

Two decades ago, Earth-based radar images showed that around both Mercury's north and south poles are deposits characterized by high radar backscatter. These polar deposits are thought to consist of water ice and perhaps other ices preserved on the cold, permanently shadowed floors of high-latitude impact craters. MESSENGER's altimeter is testing this idea by measuring the floor depths of craters near Mercury's north pole. To date, the depths of craters hosting polar deposits are consistent with the idea that those deposits occupy areas in permanent shadow.

Energetic Particle Events at Mercury

One of the major discoveries made by Mariner 10 during the first of its three flybys of Mercury in 1974 were bursts of energetic particles in Mercury's Earth-like magnetosphere. Four bursts of particles were observed on that flyby, so it was puzzling that no such strong events were detected by MESSENGER during any of its three flybys of the planet in 2008 and 2009. With MESSENGER now in near-polar orbit about Mercury, energetic events are being seen almost like clockwork.

"We are assembling a global overview of the nature and workings of Mercury for the first time," adds Solomon, "and many of our earlier ideas are being cast aside as new observations lead to new insights. Our primary mission has another three Mercury years to run, and we can expect more surprises as our solar system's innermost planet reveals its long-held secrets."

Major-element composition of Mercury surface materials

Locations of energetic electron events relative to Mercury's magnetic field

Source: NASA