Posted on 08/23/2006 10:24:06 AM PDT by Boxen
The mystery of how Earth got its Moon is one step closer to being solved.
The European Space Agency's lunar-orbiting craft called SMART-1 has completed the first detailed chemical mapping of the lunar surface. The detected chemicals, such as calcium and magnesium, give a boost to the longstanding theory that the Moon formed from the debris flung into space after a collision between early Earth and a Mars-size planet.
Calcium, in particular, is found deep inside Earth. So if the Moon has a lot of calcium, then perhaps it is made of material that was once inside our planet.
Armed with miniaturized instruments—including an ultra-compact electronic camera, an X-ray telescope the size of a toaster for mapping chemical composition, and high-tech communication gadgets—SMART-1 had lofty goals. It was to pin down out how the Moon came to exist, search for water locked up as ice in the depths of Sun-deprived craters, and map the mineral composition of the Moon's crust.
Apollo science
Prior to the Apollo missions, there was no consensus among planetary scientists regarding the Moon's formation. One theory claimed that the Earth and the Moon formed at the same time from the same disk of swirling dust and gas, while another purported that the Moon is a scoop of Earth that split off in the early stages of our solar system.
Besides sending home awe-inspiring photos, the Apollo missions delivered 842 pounds (382 kilograms) of lunar rocks and soil—the first pieces of chemical evidence to help explain the Moon's formation.
The favored theory now describes a violent collision between the Earth and a planet-size object, which hurled molten rocks and dust from both contenders into space. Over time, the debris congealed into the Moon.
With most Moon know-how coming from Apollo’s six landing sites, scientists saw lots of room for error. To solve the lunar-forming puzzle, a global investigation of the entire surface was needed.
Smart science
Enter SMART-1 (Small Missions for Advanced Research and Technology), a spacecraft equipped with seven high-tech instruments that would give a detailed map of both chemical make-up and topography over the Moon’s entire surface.
One of the most important devices, D-CIXS (pronounced dee-kicks) recorded hours of X-ray data. When the Sun’s rays hit the Moon, the X-rays caused atoms to fluoresce and emit their own X-rays. The D-CIXS (Demonstration Compact Imaging X-ray Spectrometer) telescope translated the amount of energy released into the type and abundance of different elements.
D-CIXS detected the major components of rocks: aluminum, silicon, magnesium, and calcium. However, elements like calcium are not homogenously mixed throughout the Moon. To paint a three-dimensional picture of the chemical composition, planetary scientists needed both surface and “bulk” data.
Cosmic Coincidence
What the project team is calling a cosmic coincidence helped to land that information. On January 2005, a massive solar flare flooded the Moon with X-rays. Meanwhile, the craft was peering over a region called Mare Crisium—the same location in which Russian Landers had collected soil samples in the 1970s. There, the spectrometer detected calcium in similar amounts to the data collected by the landers.
Plus, calcium showed up in broad areas across the entire lunar surface. This rock-building element lends support to the impact theory.
"From SMART-1 observations of previous landing sites we can compare orbital observations to the ground truth and expand from the local to global views of the Moon," says Bernard Foing, Project Scientist for SMART-1.
More work remains to sort out just how significant the calcium findings are.
"We have good maps of iron across the lunar surface. Now we can look forward to making maps of the other elements," said Manuel Grande of the University of Wales and D-CIXS' Principal Investigator.
The findings will be detailed in the Planetary and Space Science journal.
Dark side
Since the Moon’s rotation around its axis is equal to its orbital period, or the time it takes the Moon to travel around Earth, the same side always faces Earth. While scientists have studied samples from the Moon’s near side, the far side and its polar regions have remained in the dark.
For instance, the lunar south pole sits in the solar system’s largest crater, called the South Pole-Aitken Basin, which is 1,616 miles (2,600 kilometers) across and 7.5 miles (12 kilometers) deep. SMART-1 snapped loads of photos of the crater, while gathering chemical data. With such depths, the scientists hope to get a peek at the Moon’s mantle layer, just beneath the crust. Since the Moon accreted material over time, the deeper you go the further back in time you go.
This September, the craft’s nearly three-year mission will come to an end with a fiery crash.
As the craft nears shut-eye, its instruments will keep all eyes on the Lake of Excellence, a volcanic plain area surrounded by highlands in the mid-southern latitudes. Such close capture should give scientists insights into the formation of this region.
It doest have a near circular orbit. Also the earth's orbit is on a slightly different plane of most of the other planets. I think Pluto is the only other planet with a tilted orbit plane. Thank public schools for the dumbed down science books for thinking the orbit is circular.
The fact that the moon always faces the earth on one side and faces away on the other, should have been enough proof that it came from the earth, weather spit out from some huge explosion or a collision with a very large object.
It doest have a near circular orbit. Also the earth's orbit is on a slightly different plane of most of the other planets. I think Pluto is the only other planet with a tilted orbit plane. Thank public schools for the dumbed down science books for thinking the orbit is circular.
The fact that the moon always faces the earth on one side and faces away on the other, should have been enough proof that it came from the earth, weather spit out from some huge explosion or a collision with a very large object.
Dammit, Jim! I'm a doctor, not a moon shuttle conductor!
If you look around the universe you will see various examples of rotating bodies. They are all aggregations of matter. They are in pretty well defined structures. Consider the rings of Saturn. As they aggregate and take on more mass they will become spherical and the unequal distribution causes wobbling that eventually stabaiizes as rotation.
The moon was once a ring of particulates flung out by the collision. Time and gravity collected the particles.
Nope. The Earth orbit plane is defined by convention as at 0.00. All other planets are tilted, Mercury and Pluto being the most extreme.
It's not a strong confirmation, but just a slight encouragement. The moon very likely came from the earth, but it was not a massive interplanetary collision--that is impossible.
Not quite. The reason the Moon's rotation equals its period is something called tidal lock. Eventually (in about 50 billion years) the Earth would keep the same face to the Moon as well. However, solar physics dictates that the Sun will consume both prior to this event.
The moon has five masscons, that is five regions of excess gravity where the density of the material is higher than the rest. That is about as lumpy as it can be since its gravity will otherwise make the body spheroidal. The earth also has masscons and is nearly spheroidal.
Actually, the collision was massive (with an object that was about the size of Mars).
So the place was inhabited by evil white Europeans?
Impossible. The simple answer is that the planet exploded. Eventually planets explode just like stars go nova. It's a phase change and happens in minutes. Earth may be good for yet another explosion although it is kind of small now for that kind of activity.
apparently you've never been kept in the dark about anything. :P
I have to disagree. Exploding planets just does not make sense. Our planetary heat equilibrium is accomplished thru tectonic plate motion.
Info.
Here's something to consider: how is it that the recent particle recovery mission Stardust has captured particles that can be formed inside a planet at extreme heat and temperature but not by drifting dust? how can an asteroid that is too small to have any gravity differentiating show layers of material of definite composition?
Well doesn't that mean that all planets are in the same plane except Mecury, Earth, and Pluto? The same except those extremes.
Total BS. Once in motion it will not stop. Look up Newton.
Pick a coordinate system and stick to it. Since we are on earth most of the time, we pick earth's orbit as the zero-zero. If we were on Mars we would pick Mars' orbit as zero-zero. Or, we could pick the plane of the sun's equator, which until recently was not known as precisely as earth's orbit. Pick one.
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