Blogarchiv
Raumfahrt - Merkur-Sonde MESSENGER-Update

.12.12.2013

1000 Earth Days in Orbit around Mercury

Later today, the MESSENGER spacecraft will have completed 1,000 Earth days of flight operations in orbit around Mercury. "This milestone is a testament to the outstanding work of those who designed, tested, and operated this spacecraft," says Jim McAdams of the Johns Hopkins University Applied Physics Laboratory (APL) and the lead engineer for MESSENGER's mission design team.

"MESSENGER was designed to function for eight years following launch and to withstand the harsh environmental conditions of the inner solar system and solar heating up to 11 times greater than experienced by spacecraft near Earth," McAdams says. "The probe not only has continued to function, it has thrived, with very little loss of planned observations for more than nine years and four months since launch."
"To date, the spacecraft has returned 198,166 images from orbit about Mercury, far exceeding the mission's original plans," says APL's Rob Gold, MESSENGER's Science Payload Manager. "In the original mission concept we were planning to use half of the telemetry for images and the rest for the other instruments, and that plan would have returned about 1,000 images of the surface of Mercury. That we are now approaching 200,000 images is the result of major technological improvements made during construction of MESSENGER."
"Some of the improvements were in the hardware," he noted, "including the development of an electrically steered phased-array antenna. Others were in operational techniques, such as the use of the CCSDS (Consultative Committee for Space Data Systems) File Delivery Protocol," a highly specialized protocol designed to overcome space operations communications challenges.
The orbital phase of the MESSENGER mission, which was originally designed to last one Earth year, is now nine months into a second extended mission that is scheduled to conclude early in 2015. The lowest point of MESSENGER's orbit is now 325 kilometers (201 miles) above Mercury's surface. This minimum altitude will continue to decrease until the first maneuver of the mission's low-altitude campaign in mid-June 2014. 
"MESSENGER has not merely survived life in a tough neighborhood, it has produced a string of major scientific discoveries that have transformed our understanding of the innermost planet and how the inner solar system was formed," adds MESSENGER Principal Investigator Sean Solomon of Columbia University. "And we expect those discoveries to continue as MESSENGER begins to pass progressively closer to Mercury's surface than ever before."

.
Date acquired: November 12, 2013

Image Mission Elapsed Time (MET): 26543953
Image ID: 5181050
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 7 (748 nanometers)
Center Latitude: 80.04°
Center Longitude: 86.24° E
Resolution: 230 meters/pixel
Scale: Scene is 125 km (78 miles) from top to bottom
Incidence Angle: 90.7°
Emission Angle: 49.8°
Phase Angle: 140.6°
Of Interest: Mercury's surface has been extensively modified by tectonic activity. Giant thrust faults are thought to be the result of global cooling and contraction of the planet, and Mercury's smooth plains in particular are folded and wrinkled. With the Sun very low in the sky, the complexity of tectonic features in the northern volcanic plains is especially apparent. The wrinkle-ridge ring (also known as a "ghost crater") on the eastern edge of the scene was also captured here at more moderate illumination angles. 
This image was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map was acquired with an average resolution of 200 meters/pixel.
.
Date acquired: November 07, 2013
Image Mission Elapsed Time (MET): 26111757
Image ID: 5150263
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filter: 2 (700 nanometers)
Center Latitude: 80.79°
Center Longitude: 101.1° E
Resolution: 92 meters/pixel
Scale: Yoshikawa crater is approximately 30 km (19 miles) in diameter
Incidence Angle: 88.2°
Emission Angle: 39.2°
Phase Angle: 127.5°
Of Interest: Yoshikawa crater, named for Japanese novelist Eiji Yoshikawa, dominates the scene in today's featured image. This crater may host ice-rich deposits within its floor. Though in total shadow when it was imaged here on November 7, 2013, only a portion of the floor is permanently shadowed from the Sun's rays. The crisp rim and well-preserved field of secondary craters surrounding Yoshikawa mean that it is a relatively young crater, and any ice deposits within it must also be relatively young.
This image was acquired as part of MDIS's campaign to image within regions of permanent shadow in ice-bearing polar craters. Imaging with the WAC broadband clear filter, which has a bandwidth of 600 nanometers and is used for calibration imaging of stars, has the potential to reveal details of shadowed surfaces that are weakly illuminated by scattered sunlight. NAC images obtained with long exposure times are also acquired to seek details within shadowed regions. A variety of image exposure times and viewing conditions are employed to maximize the opportunity to resolve surface features of areas in permanent shadow.
.
Date acquired: June 17, 2012
Image Mission Elapsed Time (MET): 248431526, 248431518, 248431522
Image ID: 2033219, 2033217, 2033218
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
WAC filters: 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue
Center Latitude: 12.6°
Center Longitude: 187.0° E
Resolution: 660 meters/pixel
Scale: Nureyev crater is about 16 km (10 mi.) in diameter
Incidence Angle: 26.0°
Emission Angle: 54.1°
Phase Angle: 28.0°
Of Interest: The bright, rayed crater Nureyev is at center stage in this dramatic view toward Mercury's eastern limb. The crater's namesake is the Soviet/British ballet dancer Rudolf Nureyev, who died in 1993. This set of color images was obtained at a relatively small phase angle and consequently is dominated by variations in the inherent reflectance and color of the surface. The shape of the crater can be better perceived in an image with a larger phase angle, allowing shadows and shading to reveal the topography of the surface.
This image was acquired as part of MDIS's high-resolution 3-color imaging campaign. The map produced from this campaign complements the 8-color base map (at an average resolution of 1 km/pixel) acquired during MESSENGER's primary mission by imaging Mercury's surface in a subset of the color filters at the highest resolution possible. The three narrow-band color filters are centered at wavelengths of 430 nm, 750 nm, and 1000 nm, and image resolutions generally range from 100 to 400 meters/pixel in the northern hemisphere.
.
Date acquired: May 19, 2012
Image Mission Elapsed Time (MET): 245904903
Image ID: 1853014
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: -47.3°
Center Longitude: 177.3° E
Resolution: 179 meters/pixel
Scale: The scene is about 184 km (114 mi.) across
Incidence Angle: 47.7°
Emission Angle: 24.2°
Phase Angle: 71.9°
Of Interest: In the center of this image is a high-reflectance area that seems to be confined to a region of lower elevation that is bounded by linear scarp (cliff) segments. Such diffuse bright areas are sometimes related to the deposition of small secondary craters and ray segments by a relatively recent impact crater, but looking at regional images (for example, using QuickMap), there are no rayed craters in the immediate vicinity (though Han Kan might be a candidate). Therefore, a compositional difference may account for the difference in the albedo (brightness) of the material in the low-lying area. Are the scarps tectonic in nature (the result of vertical movement along faults), or were they formed by secondary crater chains? Also of interest in the scene are hollows on the central peak of the crater at the upper left, and the smooth impact melt on the floor of the terrace-walled crater just below center. Scientists will be at work for many years to solve the puzzle of Mercury's complicated geological history!
This image was acquired as part of the NAC ride-along imaging campaign. When data volume is available and MDIS is not acquiring images for its other campaigns, high-resolution NAC images are obtained of the surface. These images are designed not to interfere with other instrument observations but take full advantage of periods during the mission when extra data volume is available.
.
Date acquired: 22:56 UTC on November 17, 2013
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Of Interest: MESSENGER image of comet 2P/Encke during its closest approach to Mercury. At that time, Encke was approximately 2.3 million miles (3.7 million kilometers) from MESSENGER and 32.7 million miles (52.6 million kilometers) from the Sun. The image is 7° by 4.7° in size and has been slightly smoothed to enhance the faint tail of the comet. The tail was oriented nearly side on to MESSENGER in this image and is seen to stretch several degrees from the comet’s bright coma in the direction away from the Sun.
.
Date acquired: 01:54:30 UTC on November 20, 2013
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Of Interest: MESSENGER image of comet C/2012 S1 (ISON) during its closest approach to Mercury. At that time, ISON was approximately 22.5 million miles (36.2 million kilometers) from MESSENGER and 42.1 million miles (67.8 million kilometers) from the Sun. The image is 7° by 4.7° in size and has been slightly magnified and smoothed to enhance the faint tail of the comet. The tail was oriented at an angle to MESSENGER at the time and is foreshortened in this image; however, some faint structure can still be seen.
.
Quelle: NASA
.
Update: 20.12.2013
.
Beatles Legend John Lennon Among Those Honored with Mercury Craters
.
Mercury's Lennon crater, named for Beatle John Lennon, as seen from NASA's MESSENGER spacecraft.
Image Credit: 
NASA/Johns Hopkins Applied Physics Lab/Carnegie Institution
.

It’s unlikely that Mercury’s surface is populated with tangerine trees and marmalade skies, but the famous British musician who coined that phrase now has a physical presence on the planet closest to the Sun. The International Astronomical Union (IAU) has named an impact crater on the planet after John Lennon, the British pop music sensation who helped make The Beatles the most popular group of their generation.

Lennon is one of ten newly named craters on the planet, joining 114 other craters named since NASA’s MESSENGER spacecraft's first Mercury flyby in January 2008.

“The MESSENGER team is delighted that the IAU has named an additional 10 impact craters on Mercury,” said MESSENGER Principal Investigator Sean Solomon of Columbia University, who suggested Lennon. “We are particularly pleased that eight of the 10 individuals honored made all or many of their artistic contributions in the Twentieth Century, the same century in which the MESSENGER mission was conceived, proposed, and approved for flight. Imagine.”

The IAU has been the arbiter of planetary and satellite nomenclature since its inception in 1919.  In keeping with the established naming theme for craters on Mercury, all of the newly designated features are named after “deceased artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field and have been recognized as art historically significant figures for more than 50 years.”

While the notoriety and fame of the namesakes is fun, David Blewett, a MESSENGER participating scientist, says there is a practical reason for naming craters. “After a while, identifying craters by their latitude and longitude becomes laborious,” Blewett says. “Assigning names to the craters makes it easier for scientists to communicate about them, share notes and observations.”

In addition to Lennon, the newly named craters are:
 

  • Barney, for Natalie Clifford Barney (1876-1972), an American-French playwright, poet, and novelist.
  • Berlioz, for Hector Berlioz (1803-1869), a French Romantic composer best known for his compositions Symphonie fantastique and Grande messe des morts
  • Calder, for Alexander Calder (1898-1976), an American sculptor best known as the originator of the mobile, a type of kinetic sculpture made with delicately balanced or suspended components that move in response to motor power or air currents. 
  • Capote, for Truman Capote (1924-1984), an American author whose short stories, novels, plays, and nonfiction include the novella Breakfast at Tiffany's and the true-crime novel In Cold Blood
  • Caruso, for Enrico Caruso (1873-1921), an Italian tenor who sang to great acclaim at the major opera houses of Europe and the Americas and appeared in a wide variety of roles from the Italian and French repertoires that ranged from the lyric to the dramatic. 
  • Ensor, for James Sidney Ensor (1860-1949), a Belgian painter and printmaker, considered an important influence on expressionism and surrealism.
  • Giambologna, for Jean Boulogne Giambologna (1529-1608), a Dutch sculptor known for his marble and bronze statuary in a late Renaissance or Mannerist style.
  • Remarque, for Erich Maria Remarque (1898-1970), a German author best known for his novel All Quiet on the Western Front, which depicted the horrors of war from the viewpoint of young German soldiers.
  • Vieira da Silva, for Maria Elena Vieira da Silva (1908-1992), a Portuguese-born French painter of intricate, semiabstract compositions.
Quelle: NASA
.
Update: 10.02.2014
.
MESSENGER Surpasses 200,000 Orbital Images of Mercury
.
MESSENGER has now returned more than 200,000 images acquired from orbit about Mercury. The 1996 proposal for the mission promised a return of at least 1,000 images says Robert Gold, MESSENGER's Science Payload Manager. "We expected then that we would have some data compression that would probably raise the image total to somewhere near 2,000 images," says Gold, of the Johns Hopkins University Applied Physics Laboratory (APL), but scientists did not imagine then the degree to which MESSENGER would surpass that goal.
"Returning over 200,000 images from orbit about Mercury is an impressive accomplishment for the mission, and one I've been personally counting down for the last few months," says APL's Nancy Chabot, the Instrument Scientist for the Mercury Dual Imaging System (MDIS). "However, I'm really more excited about the many thousands of images that are still in MESSENGER's future, especially those that we plan to acquire at low altitudes and will provide the highest resolution views yet of Mercury's surface."
During MESSENGER's second extended mission, the spacecraft is making a progressively closer approach to Mercury's surface with each successive orbit. In about two months, each closest approach will be at a lower altitude than at any previous point in the mission, enabling the acquisition of unprecedentedly high-spatial-resolution data. For spacecraft altitudes below 350 kilometers, Narrow Angle Camera (NAC) images will be acquired with pixel scales ranging from 20 meters to as little as 2 meters. 
To commemorate the milestone, image scientists released this four-image mosaic one of the first from the MDIS low-altitude imaging campaign -- that reveals, among other features, hollows that appear to have formed in one layer in the wall of this 15-kilometer-diameter crater. 
.
Date acquired: December 05, 2013
Image Mission Elapsed Time (MET): 28560063, 65, 67, 69
Image ID: 5324381-84
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Center Latitude: 72.4°
Center Longitude: 124.9° E
Resolution: 16 meters/pixel
Scale: The height and width of each image is 8.5 kilometers (5.3 miles)
Incidence Angle: 73.4°
Emission Angle: 10.8°
Phase Angle: 81.9°
Of Interest: MESSENGER has now surpassed 200,000 images acquired from orbit about Mercury! And there are still many more to come. In particular, acquiring NAC images when the spacecraft is closest to the planet is a priority for the remainder of the mission; such images will allow the highest resolution views of Mercury's surface to be captured. The four-image mosaic shown here is one of the first from the MDIS low-altitude imaging campaign. Among the details revealed are hollows that appear to have formed in one layer in the wall of this 15-kilometer-diameter crater.
This image was acquired as part of the MDIS low-altitude imaging campaign. During MESSENGER's second extended mission, the spacecraft makes a progressively closer approach to Mercury's surface than at any previous point in the mission, enabling the acquisition of high-spatial-resolution data. For spacecraft altitudes below 350 kilometers, NAC images are acquired with pixel scales ranging from 20 meters to as little as 2 meters.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
.
The mission marks three additional milestones today: the spacecraft concludes its 12th Mercury year in orbit, its 18th Mercury sidereal day in orbit, and its 6th Mercury solar day in orbit.
"We have come an incredible way since the first mission proposal was submitted to NASA just over 17 years ago," notes MESSENGER Project Scientist Ralph McNutt of APL. "Getting to launch and then to Mercury, flyby by flyby, and into orbital operations were incredible accomplishments -- against all sorts of odds -- and yet we are now, almost routinely, noting these statistics about the mission that has literally revealed an entirely new world to humanity."
When MESSENGER was launched in August 2004, he continues, "none of the team in their wildest imagination could have foreseen the successes that we now celebrate with new data coming back week by week from the innermost planet. And we are not done. With a little more than a year left to go, before gravity brings the end to operations, we will view the planet and its environment from altitudes lower than were ever envisioned only a few short years ago -- and, as with any planetary mission providing closer and closer looks at a planetary neighbor, all we can guess is that we have not wrung all of Mercury's surprises and discoveries just yet."
Quelle: NASA

 
3425 Views
Raumfahrt+Astronomie-Blog von CENAP