mercredi 8 février 2017

NASA Receives Science Report on Europa Lander Concept











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Feb. 8, 2017

A report on the potential science value of a lander on the surface of Jupiter’s icy moon Europa has been delivered to NASA, and the agency is now engaging the broader science community to open a discussion about its findings.   


Image above: This artist's rendering illustrates a conceptual design for a potential future mission to land a robotic probe on the surface of Jupiter's moon Europa. The lander is shown with a sampling arm extended, having previously excavated a small area on the surface. The circular dish on top is a dual-purpose high-gain antenna and camera mast, with stereo imaging cameras mounted on the back of the antenna. Three vertical shapes located around the top center of the lander are attachment points for cables that would lower the rover from a sky crane, which is envisioned as the landing system for this mission concept. Image Credits: NASA/JPL-Caltech.

In early 2016, in response to a congressional directive, NASA’s Planetary Science Division began a pre-Phase A study to assess the science value and engineering design of a future Europa lander mission. NASA routinely conducts such studies -- known as Science Definition Team (SDT) reports -- long before the beginning of any mission to gain an understanding of the challenges, feasibility and science value of the potential mission. In June 2016, NASA convened a 21-member team of scientists for the SDT. Since then, the team has deliberated to define a workable and worthy set of science objectives and measurements for the mission concept, submitting a report to NASA on Feb. 7.

The report lists three science goals for the mission. The primary goal is to search for evidence of life on Europa. The other goals are to assess the habitability of Europa by directly analyzing material from the surface, and to characterize the surface and subsurface to support future robotic exploration of Europa and its ocean. The report also describes some of the notional instruments that could be expected to perform measurements in support of these goals.

Europa Mission Spacecraft - Artist's Rendering

Image above: This artist's rendering shows NASA's Europa mission spacecraft, the mission would place a spacecraft in orbit around Jupiter in order to perform a detailed investigation of the giant planet's moon Europa -- a world that shows strong evidence for an ocean of liquid water beneath its icy crust and which could host conditions favorable for life. The highly capable, radiation-tolerant spacecraft would enter into a long, looping orbit around Jupiter to perform repeated close flybys of Europa. Image credit: NASA/JPL-Caltech.

Scientists agree that the evidence is quite strong that Europa, which is slightly smaller than Earth’s moon, has a global saltwater ocean beneath its icy crust. This ocean has at least twice as much water as Earth’s oceans. While recent discoveries have shown that many bodies in the solar system either have subsurface oceans now, or may have in the past, Europa is one of only two places where the ocean is understood to be in contact with a rocky seafloor (the other being Saturn's moon Enceladus). This rare circumstance makes Europa one of the highest priority targets in the search for present-day life beyond Earth.

The SDT was tasked with developing a life-detection strategy, a first for a NASA mission since the Mars Viking mission era more than four decades ago. The report makes recommendations on the number and type of science instruments that would be required to confirm if signs of life are present in samples collected from the icy moon's surface.

The team also worked closely with engineers to design a system capable of landing on a surface about which very little is known. Given that Europa has no atmosphere, the team developed a concept that could deliver its science payload to the icy surface without the benefit of technologies like a heat shield or parachutes.


Images above: This mosaic of images includes the most detailed view of the surface of Jupiter's moon Europa obtained by NASA's Galileo mission. The topmost footprint is the highest resolution image taken by Galileo at Europa. It was obtained at an original image scale of 19 feet (6 meters) per pixel. The other seven images in this observation were obtained at a resolution of 38 feet (12 meters) per pixel, thus the mosaic, including the top image, has been projected at the higher image scale. The top image is also provided at its original resolution, as a separate image file. It includes a vertical black line that resulted from missing data that was not transmitted by Galileo. This is the highest resolution view of Europa available until a future mission visits the icy moon. The right side of the image was previously published as PIA01180. Although this data has been publicly available in NASA's Planetary Data System archive for many years, NASA scientists have not previously combined these images into a mosaic for public release. This observation was taken with the sun relatively high in the sky, so most of the brightness variations visible here are due to color differences in the surface material rather than shadows. Bright ridge tops are paired with darker valleys, perhaps due to a process in which small temperature variations allow bright frost to accumulate in slightly colder, higher-elevation locations. Images Credits: NASA/JPL-Caltech.

The concept lander is separate from the solar-powered Europa multiple flyby mission, now in development for launch in the early 2020s. The spacecraft will arrive at Jupiter after a multi-year journey, orbiting the gas giant every two weeks for a series of 45 close flybys of Europa. The multiple flyby mission will investigate Europa’s habitability by mapping its composition, determining the characteristics of the ocean and ice shell, and increasing our understanding of its geology. The mission also will lay the foundation for a future landing by performing detailed reconnaissance using its powerful cameras.

NASA has announced two upcoming town hall meetings to discuss the Science Definition Team report and receive feedback from the science community. The first will be on March 19, in conjunction with the 2017 Lunar and Planetary Science Conference (LPSC) at The Woodlands, Texas. The second event will be on April 23 at the Astrobiology Science Conference (AbSciCon) in Mesa, Arizona.

To read the complete report visit: http://solarsystem.nasa.gov/europa/technical.cfm

Related links:

Mars Viking mission: http://mars.nasa.gov/programmissions/missions/past/viking/

Europa multiple flyby mission: https://www.nasa.gov/press-release/all-systems-go-for-nasas-mission-to-jupiter-moon-europa

2017 Lunar and Planetary Science Conference (LPSC): http://www.hou.usra.edu/meetings/lpsc2017/

Astrobiology Science Conference (AbSciCon): http://www.hou.usra.edu/meetings/abscicon2017/

Europa (Moon): https://www.nasa.gov/subject/3148/europa-moon

Europa Mission: http://www.nasa.gov/europa

Images (mentioned), Text, Credits: NASA/Tricia Talbert.

Greetings, Orbiter.ch

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