On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs." --San Antonio Express-News
By culling together data from Voyager 1 and the Galileo orbiter, scientists have created a radiation map of the surface of Europa.
Using data from Galileo’s flybys of Europa two decades ago and electron measurements from NASA’s Voyager 1 spacecraft, Nordheim and his team looked closely at the electrons blasting the moon’s surface. They found that the radiation doses vary by location. The harshest radiation is concentrated in zones around the equator, and the radiation lessens closer to the poles.
Mapped out, the harsh radiation zones appear as oval-shaped regions, connected at the narrow ends, that cover more than half of the moon.
…In his new paper, Nordheim didn’t stop with a two-dimensional map. He went deeper, gauging how far below the surface the radiation penetrates, and building 3D models of the most intense radiation on Europa. The results tell us how deep scientists need to dig or drill, during a potential future Europa lander mission, to find any biosignatures that might be preserved.
The answer varies, from 4 to 8 inches (10 to 20 centimeters) in the highest-radiation zones – down to less than 0.4 inches (1 centimeter) deep in regions of Europa at middle- and high-latitudes, toward the moon’s poles.
This model, which by the way probably has large margins of error, will be used as a guide by the Europa Clipper scientists now planning that orbiter’s mission.
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