View Full Version : SELENE has a new name: Kaguya
The Planetary Society Weblog (http://planetary.org/blog/article/00000996/)
By Emily Lakdawalla
SELENE has a new name: Kaguya
Jun. 6, 2007 | 10:28 PDT | 17:28 UTC
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Japan's space agency, JAXA, announced today that the official name of their lunar mission, to be launched in August, is Kaguya. Formerly known as SELENE, Kaguya consists of three spacecraft, a main orbiter and two much smaller one known as the Relay and VRAD satellites. The three-satellite design will allow Kaguya to make a highly detailed map of the gravity field of the Moon, giving key information to the Moon's interior.
I searched around the Internet for some references to the origin of the name Kaguya. Most of my initial searches with words including "moon" and "japan" and "princess" hit upon articles about the "Sailor Moon" cartoon, but eventually I found a couple of versions of the story of the Moon princess Kaguya Hime, also known as the tale of the bamboo cutter, which appears to date back at least to the 10th century, here and here. There's a pretty multimedia version of the story for kids here (which unfortunately loads rather slowly). The basic outline of the story is that an elderly bamboo cutter discovers a beautiful baby in a grove of bamboo, and he and his wife raise the girl as their own. The beautiful girl is courted by many suitors including the Emperor, but declines all offers of marriage, seeming increasingly sad. Finally she admits to her adopted parents that she is not human but rather was sent from the Moon, and that she must soon return to the Moon. Indeed, emissaries from the Moon come and return her to her homeland. It's a lovely name for Japan's first lunar mission. I wasn't aware of the story before, but it appears to be one that all Japanese would know. I'll have to buy a story book version to read to my daughter.
There's also an asteroid named 7991 Kaguyahime. I didn't find that either "Kaguya" or "Kaguyahime" has been used to name a feature on the surface of another planet or moon.
Japan has a tradition of referring to spacecraft by rather boring code names and then renaming them shortly before or after their launch. There was Muses-A, which became Hiten; Planet-A, which became Suisei; Planet-B, which became Nozomi; Muses-B, which became Haruka (but which is also apparently referred to by acronyms HALCA and VSOP); Solar-A, now Yohkoh; Muses-C, now Hayabusa; Solar-B, now Hinode; and now SELENE has become Kaguya. Other Japanese missions yet to be renamed include Planet-C, also known as the Venus Climate Orbiter or VCO -- this one will wind up with at least four different designations before it even launches! There's a Lunar-B lander in development, and apparently there is a MUSES-D under development as well.
Click to enlarge > (http://planetary.org/image/P-044-13121.jpg)http://planetary.org/image/P-044-13121_lg.jpg
Kaguya (SELENE)
Credit: JAXA
These late name changes do create a bit of hassle, becuase of course the "SELENE" name has been used in all our URLs relating to the mission. I've run around the website making the name change in all the places I can think of -- hopefully I didn't miss anything! " :eek:
Moon Princess: Kaguya Hime.
Kaguya (SELENE) mission page. (http://planetary.org/explore/topics/kaguya/)
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The reasons I love the sea,
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I cannot explain; it's physical.
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When you dive you begin to feel like an angel.
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It's a liberation of your weight.
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Monday June 11, 2007 Crystalinks Quotations (http://www.crystalinks.com/ezine.html)
The Water of Life
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July 05, 2007
The Theia Hypothesis: New Evidence Emerges that Earth and Moon Were Once the Same
http://www.dailygalaxy.com/my_weblog/images/2007/07/05/birth_of_moon_3.jpgAccording to the giant impact hypothesis, there was once a Mars-sized body referred to as Theia orbiting in our solar system. The planet was named after the Greek Titan who gave birth to the Moon goddess Selene—a fitting name considering that the planet Theia is thought to be responsible for the birth of our moon.
Theia would have formed in about the same orbit as Earth, but about 60° ahead or behind. When the protoplanet had grown to be about the size of Mars, its size made it too heavy for its orbit to remain stable. As a result, its angular distance from Earth varied increasingly, until it finally it crashed into the Earth.
The collision would have occurred circa 4.533 billion years ago when Theia would have hit the Earth at an oblique angle, and destroyed herself in the process. Theia's mantle and a significant portion of the Earth's silicate mantle were thrust into space. The left over materials from Theia mixed with the materials from the Earth and eventually formed the Moon.
New research is validating this hypothesis, showing that the Earth’s core and the Moon’s core contain the same silicon isotopic material, which would support that the two were once a single body until a large impact separated them.
Scientists from Oxford University, University of California, and Swiss Federal Institute of Technology compared silicon isotopes from Earth rocks, as well as other materials from our solar system such as rocky materials from meteorites.
Up to about 2,900 kilometers (1,800 miles) into the Earth (not quite half way to the center), is what we know as the mantle and crust. They are predominantly formed of silicate, a compound mad of silicon, oxygen, and other elements. Past the halfway mark is a dense metallic iron material that makes up the Earth’s core.
The multinational team found that the heavier isotopes from silicate samples taken from the Earth consisted of increased amounts of the heavier isotopes of silicon. They found that Mars, the asteroid Vesta, and various chrondites (primitive meteorites that never produced ainner cores) do not contain such an arrangement, even though they have an iron core. is much smaller than the Earth (about one-eighth the size), so did not have enough mass to generate the pressure necessary to form the same core as found in the Earth.
On the other hand, the researchers found that the Moon did show a similar composition of the silicon isotopic composition as the Earth. However, it, too, is much smaller than the Earth—about one-fiftieth as large as the Earth and about one percent of the Earth’s mass—making it even less likely to have been able to generate enough pressure to form an Earth-like iron core.
However, such a core does exist at the center of the Moon, but no one can explain how it got there.
The researchers contend that the Moon indeed must have been created during a giant impact by a planet-size object (Theia) that hit during the early development of Earth. The impact was large enough that the materials, which eventually formed the Moon, mixed with the materials from the Earth, which already had a heavy silicon isotopic composition.
They state within their paper in the journal Nature: “The similar isotopic composition of the bulk silicate Earth and the Moon is consistent with the recent proposal that there was large-scale isotopic equilibration during the giant impact.”
This research is the first of its kind using isotopes in this manner and offers intriguing insights into the creation of Mars, the Earth, and the Moon. It may also help explain how life evolved on the Earth and whether or not it might have existed at some time on Mars.
Posted by Casey Kazan
Related Galaxy Posts: http://www.dailygalaxy.com/my_weblog/
July 11, 2008
H20 Detected from an Unlikely Source: Moon Volcanoes
http://www.dailygalaxy.com/my_weblog/images/2008/07/11/moon_gal.jpg As if recent reports of Mercurian rock-water weren't exciting enough, H20 has been detected from an unlikely source even closer to home: Moon Volcanoes. Yes, that's water from Moon Volcanoes, and anybody who says science is boring doesn't know what the hell they're talking about.
For years the scientific opinion of satellite matched what you'd expect from the moon mission images - a barren, dusty plain that makes the Sahara look like the sixth great lake. The moon was believed to be utterly dehydrated, constantly baked to hundreds of degrees by direct solar radiation and with gravity too weak to hold any atmosphere. Any moisture would have to be delivered by cometary impact and then hidden in shadowed craters.
Recent results from a collaboration of American universities have changed all that. All previous studies on moon samples had a minimum moisture sensitivity of fifty parts per million; it turns out the precious water was hiding down at the forty-six per million mark. Analysing samples of volcanic glass beads with the new technique of Secondary Ion Mass Spectrometry (SIMS) the bashful water was finally detected.
The distribution of H20 in the samples is consistent with the original material being relatively rich in water, about as much as the Earth's upper mantle, but the volcanic processes causing 95% of it to be lost. While most would have escaped into space, some is thought to have collected at the lunar poles in shadowed regions. Ready-made ice-banks just waiting to be tapped by future lunarnauts.
Posted by Luke McKinney.
Related Galaxy posts:
The Theia Hypothesis: New Evidence Emerges that Earth and Moon Were Once the Same
http://www.dailygalaxy.com/my_weblog/2008/07/h20-detected-fr.html
Source: Lunar Water http://www.eurekalert.org/pub_releases/2008-07/ci-mwd070708.php
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Space
____________ First gravity map of Moon's far side unveiled
00:00 16 February 2009 by Rachel Courtland
For similar stories, visit the Solar System Topic Guide (http://www.newscientist.com/article/dn16606-first-gravity-map-of-moons-far-side-unveiled.html)
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The Japanese probe Kaguya has created the first map of gravity differences on the far side of the Moon, which always points away from Earth. The gravity signatures of some craters suggests the far side might have been stiffer and cooler than expected (Illustration: Namiki et al/AAAS)
The first detailed map of the gravity fields on the Moon's far side shows that craters there are different than those on the near side. The results could reveal more about the Moon as it was billions of years ago, when magma flowed across its surface.
The new gravity map was collected by the Japanese lunar satellite Kaguya, which released two small probes into orbit around the Moon in 2007.
The motions of the three spacecraft, which are sensitive to variations in the Moon's gravity field, were measured by tracking their radio signals.
Crucially, while the main Kaguya spacecraft was on the far side of the Moon and therefore out of direct contact with Earth, one of the small probes relayed its signals to Earth.
The resulting map - the first detailed one completed of the Moon's far side - shows that craters on the far side have a markedly different gravity signature from those on the side that always faces Earth.
'Fabulous data'
That suggests that billions of years ago, there might have been large differences in the temperature or thickness of the Moon's two halves.
"It's fabulous new data," says Walter Kiefer, a planetary geophysicist with the Lunar and Planetary Institute in Houston, Texas, who was not part of the study. "We haven't been able to get a good look at the far side until now."
Most of the large craters on the Moon formed more than 3.8 billion years ago. These were partly filled in by magma that flowed on the surface before the Moon cooled and its geological activity died down.
But a number of craters also seem to have been filled in from below. Researchers believe material from the mantle also rose up in craters, since these are sites where impacts had thinned the Moon's crust.
The new Kaguya measurements reveal some craters on the far side that seem to have been filled only with mantle. These craters have higher-than-normal gravity at the centre, surrounded by a thick ring of low gravity that closely matches the original low elevation of the crater.
Opposite conclusions
It is not yet clear what these new crater measurements suggest about the early Moon. In order for these structures to survive, the lunar far side must have been too cool and stiff to allow the mantle at the craters' centres to smooth out much over time, says team leader Noriyuki Namiki, of Japan's Kyushu University. "The surface had to be very rigid to support these structures," Namiki says.
But Keifer says the low gravity rings could argue for the opposite scenario. The structures in the centres of the craters might be narrow because the top layer of the Moon's far side was too thin and warm to be able to hold up anything larger. Comparing the Kaguya observations with models could help settle the question, Kiefer says.
The Moon's two halves also show other striking differences. NASA's Lunar Prospector, which operated in the late 1990s, found that radioactive elements seem to be concentrated on the near side. The far side also shows less evidence of past volcanic activity.
Journal reference: Science (vol 323, p 900)
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