Samstag, 18. Juli 2015 - 21:30 Uhr

Raumfahrt - NASA-Raumsonde Dawn im Orbit von Zwergplaneten Ceres - Update-5



Twinkle, Twinkle, Little Ceres: Dwarf Planet's White Spots Shine in New Pic

The clearest photos yet of dwarf planet Ceres have been sent back by NASA's Dawn spacecraft, and the mysterious white spots are as bright as ever and more defined than before. But that doesn't mean scientists know what they are."Reflection from ice is the leading candidate in my mind," Chris Russell, principal investigator for the Dawn mission, said in a NASA statement. "But the team continues to consider alternate possibilities, such as salt. With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon."
Craters stud the northern hemisphere of Ceres. NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
The new shots were taken from about 2,700 miles away on June 6, during the probe's second mapping orbit. Dawn will make a few more passes at this distance (each orbit takes about three Earth days), then advance (or descend, depending on your frame of reference) to 900 miles from Ceres sometime in August. The improved resolution of photos, temperature and geographic data will hopefully give scientists the boost they need to solve the mystery of the white spots and make further theories about this ancient object residing in our solar system.
Quelle: NBC-News

Latest close-up of Ceres' bright spots

New images from NASA's Dawn spacecraft show the surface of the dwarf planet Ceres in sharper detail than ever before, yet certain features continue to puzzle scientists. Some of the first images, taken during Dawn's second mapping orbit at an altitude of 4,400 km (2,700 miles), are of the mysterious bright spots that lie in a crater about 90 km (55 miles) across. Scientists are still unsure about the nature of the cluster of spots which appear to be of various sizes. Chris Russell, principal investigator for the Dawn mission based at the University of California, said in a statement: "The bright spots in this configuration make Ceres unique from anything we've seen before in the Solar System. The science team is working to understand their source. Reflection from ice is the leading candidate in my mind, but the team continues to consider alternate possibilities, such as salt. With closer views from the new orbit and multiple view angles, we soon will be better able to determine the nature of this enigmatic phenomenon." Other images from Dawn's visible and infrared mapping spectrometer (VIR) show a region of Ceres' cratered northern hemisphere and include a true-colour view and a temperature image taken in the infrared light range. It is hoped that VIR will help finally to solve the puzzle of the bright spots. Dawn will continue to observe Ceres in its current orbits of about three days each, until June 28, before moving to its next orbit at an altitude of only 1,450 km (900 miles) in early August.
Images from Dawn's visible and infrared mapping spectrometer (VIR) show a portion of Ceres' cratered northern hemisphere. From top to bottom: a black-and-white image; a true-colour view and a temperature image. Image credit: NASA/JPL-Caltech/UCLA/ASI/INAF 
Quelle: SEN
Update: 17.06.2015

NASA's Dawn Probe Focuses on a Different Mystery Spot on Ceres

This image, taken by NASA's Dawn spacecraft, shows dwarf planet Ceres from an altitude of 2,700 miles (4,400 kilometers). The June 6 image has a resolution of 1,400 feet (410 meters) per pixel. NASA / JPL-Caltech / UCLA / MPS / DLR / IDA
Now here's a spot of a different color: The latest picture released by the science team for NASA's Dawn mission shows a bright patch on the dwarf planet Ceres that's distinct from the eerie "alien headlights" seen in other imagery.
The best-known collection of bright spots on Ceres is known as "Spot 5," and the best guess is that those spots are made of ice deposits — although scientists haven't completely ruled out the possibility that they're made of salt or some other light-colored material.
Quelle: NBC-News
Update: 20.45 MESZ

UCLA-led NASA mission provides closest ever look at dwarf planet Ceres

First images from Dawn spacecraft produce 3D model of the ‘mysterious’ terrain

A NASA mission led by UCLA professor Christopher Russell has released new images of the dwarf planet Ceres, the largest asteroid between Mars and Jupiter.
The photos were produced by the spacecraft Dawn, which is now observing Ceres from 2,700 miles above its surface; NASA has also produced a one-minute video animation that sheds new light on this mysterious and heavily cratered world.
“Everything we learn from Ceres will be absolutely new,” said Christopher Russell, a UCLA professor of space physics and planetary science, and the Dawn mission’s principal investigator. “We approach it in awe and almost total ignorance.”
Dawn’s visit to Ceres, which is scheduled to last more than a year, began on March 6. From July 2011 to September 2012, it observed Vesta, a “minor planet” that is the second most massive body in the asteroid belt between Mars and Jupiter.
Over the years, scientists have learned about the conditions at the beginning of the solar system by studying meteorites from Vesta that have fallen to Earth. There have been no such meteorites produced by Ceres, an indication that the two bodies are likely very different. For example, Dawn found little evidence to indicate there is water on Vesta. But Russell said Ceres could have a substantial amount of water or ice beneath its rocky crust.
The presence of water, he said, could “affect the time for relaxation of craters and mountains on Ceres and reduce the height of the topography compared to Vesta, and will affect minerals on the surface.” Russell also said Ceres, unlike Vesta, might have a weak atmosphere and perhaps even life.
Dawn, which launched from Cape Canaveral, Florida, in 2007, is the first NASA spacecraft to visit a dwarf planet and the first to orbit two celestial bodies beyond the moon.
Scientists expect the mission to provide insights about Ceres’ shape, size, composition, internal structure, and tectonic and thermal evolution. The findings also should provide new understanding about the conditions under which Ceres and Vesta were formed.
Dawn is powered by an advanced NASA technology known as ion propulsion that enables it to use fuel more than 10 times more efficiently than standard rockets. It is outfitted with two high-resolution cameras (including one backup), a visible and near-infrared mapping spectrometer to identify minerals on the surface, and a gamma ray and neutron spectrometer, which will be used to reveal the presence of elements such as iron and hydrogen in the soil.
NASA has reported that Dawn’s price tag — including the construction and launch of the space craft and 10 years of operations — is $472 million. Russell said the Dawn mission is actually very cost-efficient compared with other means of space exploration. Separate missions to Ceres and Vesta would likely have cost more than double that amount.
Russell and his team are in charge of Dawn’s scientific research — with the lead role in analyzing and interpreting data from the space craft — and public outreach. In 2014, they received the Trophy for Current Achievement, the National Air and Space Museum’s highest honor in the fields of aerospace science and technology.
“The Dawn flight team and the Dawn science team are high achievers, but the spacecraft itself is the highest achiever,” Russell said.
The Dawn mission is managed by NASA’s Jet Propulsion Laboratory, a division of Caltech, for the agency’s Science Mission Directorate. Team members include scientists from JPL, the NASA Goddard Space Flight Center, the Planetary Science Institute, the Massachusetts Institute of Technology and other institutions. The mission’s international partners include the Max Planck Institute for Solar System Research in Gottingen, Germany, the DLR Institute for Planetary Research in Berlin, the Freie Universitaet of Berlin, the Italian National Institute for Astrophysics in Rome, and the Italian Space Agency. 

Quelle: UCLA
Update: 22.06.2015

Viele helle Flecken und ein pyramidenförmiger Berg auf Ceres

Zurzeit kreist die Raumsonde Dawn in einem Beobachtungsorbit um Zwergplanet Ceres und blickt aus 4400 Kilometern Höhe auf seine Oberfläche: Aufnahmen mit der Kamera an Bord zeigen nun nicht nur weitere rätselhafte hellen Flecken, sondern auch einen pyramidenförmigen Berg, der in einem ebenen Gelände nach Schätzung der Wissenschaftler rund fünf Kilometer in die Höhe ragt. "Die doch beachtliche Anzahl an hellen Ablagerungen lassen vermuten, dass auf Ceres frisches Material an die Oberfläche gelangt. Auch der sehr steile Berg ist ein Beleg für besondere Aktivitäten in der Kruste", sagt Prof. Ralf Jaumann, Planetenforscher am Deutschen Zentrum für Luft- und Raumfahrt (DLR) und Wissenschaftler der amerikanischen Dawn-Mission.
Helle Flecken im Detail
Schon bei der Annäherung an Ceres, den die Dawn-Sonde am 6. März 2015 erreichte, faszinierten rätselhafte helle Flecken die Planetenforscher. Die Spannung stieg mit jeder weiteren Aufnahme, die die Kamera zur Erde sendete. Eine Erklärung für diese stark reflektierenden Regionen auf der Oberfläche des Zwergplaneten konnte bisher noch nicht eindeutig gefunden werden - unter anderem Eis oder Salz könnten der Ursprung dieses Phänomens sein. Am 5. Juni 2015 erreichte Dawn den "Survey Orbit" in 4400 Kilometern Höhe und zumindest eines wird auf einer Aufnahme vom 9. Juni 2015 deutlich: Innerhalb eines Kraters mit etwa 90 Kilometern Durchmesser sind mindestens acht weitere helle Flecken zu erkennen. Sie befinden sich nahe eines besonders hellen Gebietes mit einem Durchmesser von rund neun Kilometern. Mit Spektralmessungen wollen die Wissenschaftler während der Mission herausfinden, aus welchem Material die hellen Flecken bestehen.
Berg in Pyramiden-Form
Neben den hellen Flecken zeigen die Kamerabilder aber auch erstmals deutlich einen steilen, pyramidenförmigen Berg, aufgenommen am 14. Juni 2015. Er ragt rund fünf Kilometer aus einem relativ flachen Gelände auf Ceres heraus. Auch zahlreiche Krater haben in ihrem Mittelpunkt einen Berg. Außerdem entdecken die Planetenforscher mehr und mehr Hinweise auf Aktivitäten an der Oberfläche des Zwergplaneten - dazu gehören fließförmige oder eingesunkene Strukturen sowie Hangrutschungen. Ceres scheint damit mehr Überbleibsel ehemaliger und vielleicht vor Kurzerm entstandene Aktivität zu zeigen als Vesta, der Asteroid, den die Dawn-Sonde von Juli 2011 bis August 2012 erkundete. "Ceres scheint durch viel komplexere geologische Prozesse geprägt worden zu sein als bisher vermutet", sagt DLR-Planetenforscher Prof. Ralf Jaumann.
Noch bis zum 30. Juni 2015 bleibt Dawn im Beobachtungsorbit und wird sich dann bis zum 4. August 2015 Ceres‘ Oberfläche bis auf 1450 Kilometer Entfernung nähern. Dann wird sich auch die Auflösung der Kamerabilder von bisher 410 Meter pro Bildpunkt auf 140 Meter pro Bildpunkt verbessern. Das DLR-Institut für Planetenforschung verfeinert mit diesen Daten das bereits erstellte dreidimensionale Höhenmodell des Zwergplaneten.
Die Mission
Die Mission DAWN wird vom Jet Propulsion Laboratory (JPL) der amerikanischen Weltraumbehörde NASA geleitet. JPL ist eine Abteilung des California Institute of Technology in Pasadena. Die University of California in Los Angeles ist für den wissenschaftlichen Teil der Mission verantwortlich. Das Kamerasystem an Bord der Raumsonde wurde unter Leitung des Max-Planck-Instituts für Sonnensystemforschung in Göttingen in Zusammenarbeit mit dem Institut für Planetenforschung des Deutschen Zentrums für Luft- und Raumfahrt (DLR) in Berlin und dem Institut für Datentechnik und Kommunikationsnetze in Braunschweig entwickelt und gebaut. Das Kamera-Projekt wird finanziell von der Max-Planck-Gesellschaft, dem DLR und NASA/JPL unterstützt.
Quelle: DLR
Update: 24.06.2015

Dawn Mission Reveals More Detail in Mysterious Ceres

From its orbital perch 2,700 miles above Ceres, NASA’s Dawn spacecraft returned new images of the dwarf planet showing more even more small bright spots inside a 55-mile crater.
At least eight bright areas now have been found next to a large white region glinting inside the crater. Scientists suspect they are seeing some kind of highly reflective material, such as ice or salt, but there are other options as well, like geysers, volcanoes or rock.
The new images, which were taken on June 9 and released today (June 22), also show that Ceres has a steep, three-mile high mountain rising from the surface in an area that is otherwise relatively smooth and flat.
On June 6, Dawn took a picture of what looks to be a pyramid-shaped mountain, upper right, rising about three miles from the surface. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Several craters, many with central peaks, have been discovered, along with landslides, flows and collapsed structures that are evidence of past surface activity.In August, Dawn is scheduled to make more observations of Ceres from a lower orbit just 900 miles above the surface.
Quelle: D-News
Update: 11.07.2015 

The weird white spots on Ceres might not be ice after all

Pluto may be the star of the dwarf planet scene for the next few days, but let's not forget about Ceres: We've been salivating over the mysterious white spots on its surface since NASA's Dawn orbiter sent its first photos home. But according to the mission's principal investigator, the crowd favorite theory -- that the spots are made of some kind of water or ice -- is probably about to be debunked.
According to Christopher Russell of the University of California at Los Angeles, the Dawn mission's principal investigator, the team is "shying away from there being ice on the surface."
"The general consensus on the team right now is that water is definitely a factor on Ceres, but that the spots themselves are more likely to be just highly reflective salt, rather than water," Russell told The Post.
The mystery is far from completely solved, Russell cautioned. The team failed to get the quality of measurements they wanted in examining the spots, and they'll have to try again at a closer orbit -- like the next planned mapping orbit, which will take them from 2,700 miles over the surface to just 900. The photos taken at that height will also have significantly better resolution, which should further help the team determine what the spots are made of.
But based on the spectral data the team did get, Russell said, the spots "really don't look like mounds of ice."
Quelle: The Washington Post
Update: 18.07.2015

Mission Status Report
NASA's Dawn spacecraft is using its ion propulsion system to descend to its third mapping orbit at Ceres, and all systems are operating well. The spiral maneuvering over the next five weeks will take the spacecraft to an altitude of about 900 miles (less than 1,500 kilometers) above the dwarf planet.
The spacecraft experienced a discrepancy in its expected orientation on June 30, triggering a safe mode. Engineers traced this anomaly to the mechanical gimbal system that swivels ion engine #3 to help control the spacecraft's orientation during ion-thrusting. Dawn has three ion engines and uses only one at a time.
Dawn's engineering team switched to ion engine #2, which is mounted on a different gimbal, and conducted tests with it from July 14 to 16. They have confirmed that the spacecraft is ready to continue with the exploration of Ceres.
By the end of the day on July 17, Dawn will have descended to an altitude of about 2,400 miles (3,900 kilometers). After arrival at its next mapping orbit -- called the High-Altitude Mapping Orbit, or HAMO -- in August, Dawn will begin taking images and other data at unprecedented resolution.
Quelle: NASA

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