- The picture included shows what the Moon looks like with a topological gravitational map. Two satellites orbiting the Moon measured the gravitational force of the surface below as they passed 34 miles overhead. The color shows areas that have more mass, the mountains, and other areas that have less mass, the craters.
-
- The same type of map was created for the Earth. The Earth satellite project was called GRACE, Gravity /recovery and Climate Experiment, launched in 2002.
-
- The Moon satellites are called project GRAIL, Gravity Recovery ad Interior Laboratory , launched in 2011. GRAIL has measured the Moon’s internal structure and composition in unprecedented detail. The map reveals such features as tectonic structures, volcanic land forms, basin rings, crater central peaks, crater bowls. The data has revealed long, linear gravity anomalies crisscrossing the surface for hundreds of miles. These appear to be dikes of long, thin vertical bodies of solidified magna in the subsurface.
-
- The measurements were accomplished by 2 washing machine-sized satellites that were in tandem orbits, near circular orbits, 34 miles above the surface. A laser beam precisely measured the distance between the two satellites. Named “Ebb” and “Flow” as the lead satellite passed over a surface of more mass it speeds up ever so slightly due the increase pull of gravity. The distance between the satellites lengthen. Later, as the tandem satellite passes over the same spot it speeds up shortening the distance between them again and confirming the gravity measurement.
-
- These changes in the gravity field were transmitted to Earth where astronomers synced up the changes with the surface topography features.
-
- The gravity field has preserved the record of the Moon’s impact bombardments. The data found the bulk density of the Moon’s highland crust is substantially lower than expected. But, it matches the local samples returned by the Apollo astronauts. In total the Apollo missions brought back 800 pounds of rocks.
-
- The average thickness of the Moon’s crust is between 21 and 27 miles. The bulk composition of the crust is similar to that of Earth supporting the theory that the Moon was created from a giant impact splash by an asteroid the size of Mars. Mars is 11% the mass of the Earth.
-
- You can see a different Moon today thanks to the Ebb and Flow mission. Google the GRAIL project for videos and pictures of the Moon’s gravity map. An announcement will be made shortly, stay tuned.
-
-------------------------- ------------------------------------------------------------------
RSVP, please reply with a number to rate this review: #1- learned something new. #2 - Didn’t read it. #3- very interesting. #4- Send another review #___ from the index. #5- Keep em coming. #6- I forwarded copies to some friends. #7- Don‘t send me these anymore! #8- I am forwarding you some questions? Index is available with email and with requested reviews at http://jdetrick.blogspot.com/ Please send feedback, corrections, or recommended improvements to: jamesdetrick@comcast.net.
or, use: “Jim Detrick” www.facebook.com, or , www.twitter.com.
707-536-3272, Sunday, December 9, 2012
No comments:
Post a Comment