Lunar rocks help build new theory of moon's origin
It's one of the oldest astronomical puzzles - whence came the moon? Is it a fragment split off from the early Earth? Did it wander in from outer space to be captured? Or did Earth and moon form together from the primordial solar nebula as a kind of twin planet system?
Scientists still lack a definitive answer. But continued study of moon rocks and other space-age lunar data suggests to some scientists that Earth and moon had a common origin.
In fact, as interpreted by British geophysicist S. Keith Runcorn, magnetism in moon rocks suggests the moon itself once was circled by its own system of moonlets. Crashing into the moon some 4.2 to 3.8 billion years ago, these satellites may have created the great dark areas of the lunar ''seas.'' The impacts may also have tilted the moon and started a process of crustal drift that shifted the ancient moon's north and south poles by up to 90 degrees.
This is the current conclusion of a theory that Runcorn - who heads the Institute of Lunar and Planetary Sciences at Newcastle University - has been developing and promoting for over a decade. It began as a minor scientific heresy.
Unlike Earth, the moon was believed never to have had a general magnetic field. Indeed, it was thought never to have had a liquid-iron core, as does Earth, which generates a magnetic field as it spins with the planet. Yet the moon rocks brought back by Apollo astronauts had residual magnetism. In contrast to many other lunar scientists, Runcorn and his colleagues took this fact at face value as evidence that the moon once had a respectable magnetic field. When the rocks formed, they ''froze'' in a record of that field which can be read today.
This has led to the far-reaching conclusions Runcorn outlined in a recent issue of Nature.
To begin with, the rocks indicate that, about 4 billion years ago, the moon had a magnetic field about twice that of Earth. This lunar magnetism has since decayed substantially. This is consistent with the theory of an originally liquid-iron core that later froze. It's hard to know what heated the core initially. Runcorn says it might have been radioactivity. But he notes that this still is a puzzle.
The way the rocks are magnetized also suggests to Runcorn that the moon's magnetic north pole and rotation axis have shifted substantially, perhaps several times, in the remote past. This he attributes to the impact of debris that had been orbiting the moon. Runcorn notes that this is suggested by lines of impact scars - especially the big lunar mare basins - along what would have been the moon's equator nearly 4 billion years ago.
Thus, Runcorn concludes that the moon once had its own system of moonlets. This, in turn, implies that Earth and moon formed together out of the same primordial material with the moonlets forming from leftover debris.
The moon rocks' residual magnetism was, as Runcorn notes, ''the first, and perhaps the most unexpected,'' of the major discoveries of Project Apollo. The conclusions he has drawn from this discovery are speculative. But whether or not they all turn out to be right, they illustrate the kind of new insight scientists have gained by having a piece of the moon in hand rather than having to study that body from afar. Beaver landscape 'architects'
Archaeologists know that much of Northern Europe's rich forest cover was destroyed some 5,000 years ago as neolithic people took up farming. But trees were destroyed in some parts of Europe before farming began. Archaeologists John Coles of Britain's Cambridge University and Bryonysp? Orme of the University of Exeter say it probably was the work of beavers.
Indeed, they say that in reshaping Europe's prehistoric landscape the beaver was ''second only or equal to man.''
Beavers feed on wood and bark. They fell trees for food and to build dams. The dams create artificial lakes where beavers can live. Eventually, the beavers move on as the trees run out. The lakes drain as the dams decay. Then they turn into meadows.
As reported in New Scientist, Coles and Orme point out that such beaver-created meadows would be ideal for Stone Age people. They would offer sites with lots of dead wood for fires or construction. Deer and elk could be hunted there. The land would also be fertile and easy to till.
The two archaeologists are joint directors of the Somerset Levels Project. They began to suspect the role of beavers when they recognized that logs found at Stone Age wetland sites had been felled by chewing. The ancient people had merely reused what beavers had supplied. Archaeologists, it seems, need to consider the beaver as well as man in assessing ancient landscape changes. Captive flavors
In some dairy products, such as cheese, it's molds and other microbes that provide the flavor. They also limit shelf life, while processing cheese to improve storage kills the flavormaking organisms. Norman F. Olson and colleagues at the University of Wisconsin are developing a method to preserve flavor and extend shelf life, too.
They are extracting the enzymes and other flavormaking materials from the microbes and encapsulating them in globules of butterfat. These globules, only about a hundredth of a millimeter across, can be added to cheese after processing. This leads to better flavor control than is possible when the enzymes are added directly.
Olson told a recent meeting of the American Chemical Society that, with this system, it looks as though ''flavors can be produced at controlled rates to specified stable levels.''