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GRAIL Probes Set to Begin Lunar Orbit Saturday, Sunday |
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Saturday, 31 December 2011U.S. space agency NASA says its twin lunar spacecraft that are on a mission to study the Moon’s gravitational field and internal structure are set to begin orbiting Earth’s satellite on Saturday and Sunday.
NASA launched the two unmanned Gravity Recovery and Interior Laboratory, or GRAIL, probes in September. It says the first probe, GRAIL A, is scheduled to be placed into its lunar orbit on Saturday, beginning at 2121 Universal time [4:21 p.m. EST Saturday). The second probe, GRAIL B, will start its orbit placement on Sunday at 2205 Universal time [5:05 p.m. EST Sunday].
The orbiting GRAIL spacecraft are scheduled to spend about 90 days gathering data to create the first complete high-resolution map of the Moon’s curiously uneven gravitational field. Scientists say they will use the new gravity data to find out what goes on beneath the lunar surface, “from crust to core.”
Mission principal researcher, Maria Zuber of the Massachusetts Institute of Technology, said the GRAIL project will “rewrite the textbooks on the evolution of the Moon.”
NASA says it expects insights from the GRAIL mission to lead to a better understanding of how the Earth and the three other rocky planets [Mercury, Venus and Mars] in the inner solar system developed into the diverse worlds seen today.
The GRAIL A and GRAIL B orbital maneuvers on Saturday, December 31 and on Sunday, January 1 happen to coincide with New Year’s Eve 2011 and New Year’s Day 2012.
NASA anticipates that GRAIL’s comprehensive map of the Moon’s gravitational field also will provide an important navigational tool for future lunar spacecraft. The space agency says it plans to plunge both GRAIL spacecraft into the lunar surface several weeks after the orbital mapping mission is complete.
The Moon orbits the Earth from an average distance of about 385,000 kilometers. It has a diameter of nearly 3,500 kilometers. By contrast, the Earth’s is 12,756 kilometers wide. Because the Moon is smaller and has less mass, the force of gravity on the lunar surface is only 17 percent of that on the Earth. That means the same object that weighs 100 kilograms here on Earth will weigh only 17 kilograms on the Moon.
Astronomers believe the Moon formed only 30 to 50 million years after the rest of our solar system first coalesced from left over stellar dust and gas some 4.6 billion years ago. The dominant theory proposes that the Moon is made of debris that circled the still-molten Earth in the wake of a cataclysmic collision with a smaller Mars-sized protoplanet.
Just a day after ending an official period of mourning, North Korea wasted no time bluntly telling the world not to expect any policy changes from Pyongyang.
The National Defense Commission issued a statement. It admonishes what it called "foolish politicians around the world" - especially those in South Korea - not to expect any change from the North.
The statement was broadcast for 11 minutes at noon Friday on North Korean television. It reverted to a very tough tone about South Korea and its leader. President Lee Myung-bak is termed the head of a traitor group whose "evil misdeeds" have climaxed by failing to allow Koreans in the South to pay their final respects to Kim Jong Il.
The announcer, reading the statement, calls South Korea's president "clueless" when it comes to policy regarding the North. She says North Korea will shun his administration forever.
Georgetown University professor Balbina Hwang, a former State Department adviser on Korean policy, notes this is tough rhetoric, even by North Korean standards.
"The tenor, the sheer vitriol in the language that is used and in the tone of which, this sort of raging, specifically about South Korea and President Lee Myung-bak, it is a bit unusual," said Hwang.
Hwang says she views this as reflecting a sense of insecurity in North Korea's powerful National Defense Commission.
"I don't think any institution that does feel secure in its own power would feel the necessity to come out with such strong language and in such an intense way," she said.
Although President Lee has taken a harder line with the North than his two predecessors, in recent months he had been signaling a more flexible approach toward Pyongyang.
Whether that will still be the case, with the Kim Jong Un era beginning in North Korea, will likely be revealed in Seoul on Monday.
That is when President Lee delivers his New Year's address. Officials at the presidential Blue House tell say that it will, in great part, be devoted to his outlook on the future of inter-Korean relations. |
Saturday, 31 December 2011
VOA News
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