lundi 3 octobre 2016

NASA’S MAVEN Spacecraft Celebrates One Mars Year of Science












NASA - Mars Atmosphere and Volatile Evolution (MAVEN) patch.

Oct. 3, 2016

Today, NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission completed one Mars year of science observations. One Mars year is just under two Earth years.

Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. Image Credit: NASA

MAVEN launched on Nov. 18, 2013, and went into orbit around Mars on Sept. 21, 2014. During its time at Mars, MAVEN has answered many questions about the Red Planet.

The spacecraft has made the following discoveries and science results:

- Most complete determination of the rate of loss of gas from the atmosphere to space and of how it is controlled by the sun, both during quiet times and during solar-storm events. - NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere:
http://orbiterchspacenews.blogspot.ch/2015/11/nasa-mission-reveals-speed-of-solar.html

- Most thorough and accurate determination of the rate of escape of atmospheric gas to space in present time. - NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere:
http://orbiterchspacenews.blogspot.ch/2015/11/nasa-mission-reveals-speed-of-solar.html

- Most thorough determination of how the sun controls the structure, composition, and variability of the Mars upper atmosphere, leading to escape of gas from the top of the atmosphere to space. - NASA Mission Reveals Speed of Solar Wind Stripping Martian Atmosphere:
http://orbiterchspacenews.blogspot.ch/2015/11/nasa-mission-reveals-speed-of-solar.html

- Discovery of a cloud of dust surrounding Mars that likely is interplanetary dust (debris from comets) that is falling in toward Mars. - NASA Spacecraft Detects Aurora and Mysterious Dust Cloud around Mars: http://orbiterchspacenews.blogspot.ch/2015/03/nasa-spacecraft-detects-aurora-and.html

- Discovery of a layer of metal ions in the ionosphere that comes from the falling in of interplanetary dust. - Close Comet Flyby Threw Mars’ Magnetic Field Into Chaos: http://orbiterchspacenews.blogspot.ch/2016/03/close-comet-flyby-threw-mars-magnetic.html

- Discovery of diffuse aurorae that are widespread over the planet and that do not depend on the presence of a global or local magnetic field to focus the particles from the sun that drive them. - http://www.nasa.gov/image-feature/goddard/maven-captures-aurora-on-mars

- Detection of a “polar plume” of ions escaping to space that had not previously been seen. - https://www.nasa.gov/feature/goddard/rock-star-mars

- A sharpened ultraviolet view of Mars was acquired when the Imaging Ultraviolet Spectrograph team took advantage of the higher data rates possible during the recent close passage between Earth and Mars to collect its highest resolution data:


Image above: MAVEN's Imaging UltraViolet Spectrograph obtained this image of Mars on July 13, 2016, when the planet appeared nearly full when viewed from the highest altitudes in the MAVEN orbit. The ultraviolet colors of the planet have been rendered in false color, to show what we would see with ultraviolet-sensitive eyes. The ultraviolet (UV) view gives several new perspectives on Mars. Valles Marineris, a two-thousand-mile canyon system, appears prominently across the middle of the image as a blue gash. The deep canyon appears blue due to the scattering of ultraviolet light by the atmosphere, so strong that we cannot make out the bottom of the canyon. The greenish cast of the planet as a whole is a combination of the reflection of the surface plus the atmospheric scattering. The three tall Tharsis volcanoes appear near the left edge, dotted by white clouds forming as the winds flow over them. Bright white polar caps appear at both poles, typical for this season, in which there is a transition from southern-hemisphere winter to summer. The magenta-colored region visible at the south pole shows where ozone is absorbing ultraviolet light — the same property of ozone that protects life on Earth from harmful UV radiation. While ozone tends to be destroyed by chemical processes in the winter on Earth, different atmospheric chemistry at Mars caused it to build up in the winter there. A hint of ozone is also visible near the north pole; more will accumulate there as winter is coming. IUVS obtains images of Mars every orbit when the sunlit portion of the planet is visible from high altitude. Image Credits: NASA/Goddard/University of Colorado/LASP.

“Taken together, the MAVEN results tell us that loss of gas from the atmosphere to space has been the major force behind the climate having changed from a warm, wet environment to the cold, dry one that we see today,” said Bruce Jakosky, MAVEN principal investigator, from the University of Colorado in Boulder.

NASA recently declared that MAVEN had achieved mission success during its primary mission.  Mission success means that the spacecraft operated as intended, made the expected science measurements, and achieved its proposed science objectives.

MAVEN has been approved for an additional two-year extended mission that will run through the end of September 2018.

All spacecraft systems and science instruments continue to operate as expected.  Data is being collected and measurements are extending to a second Mars year and to a different phase in the eleven-year cycle of solar activity. The science team is implementing additional ways of operating the instruments to expand on the science achieved during the primary mission.

MAVEN’s principal investigator is based at the University of Colorado’s Laboratory for Atmospheric and Space Physics, Boulder. The university provided two science instruments and leads science operations, as well as education and public outreach, for the mission. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the MAVEN project and provided two science instruments for the mission. Lockheed Martin built the spacecraft and is responsible for mission operations. The University of California at Berkeley’s Space Sciences Laboratory also provided four science instruments for the mission. NASA’s Jet Propulsion Laboratory in Pasadena, California, provides navigation and Deep Space Network support, as well as the Electra telecommunications relay hardware and operations.

For more information about Mars Atmosphere and Volatile Evolution (MAVEN), visit: https://www.nasa.gov/mission_pages/maven/main/index.html

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Nancy Neal Jones/Karl Hille.


Greetings, Orbiter.ch

Aucun commentaire:

Enregistrer un commentaire