Preserving the Laetoli Footprints
The discovery of hominid footprints in East Africa reshaped the study of human origins. Now conservators have protected the fragile tracks from destruction
Volume 279, Issue 3
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Features
Weightlessness and the Human Body
The effects of space travel on the body resemble some of the conditions of aging. Studying astronauts' health may improve medical care both in orbit and on the ground
Making New Elements
Three new elements--110, 111 and 112--have been produced over the past several years. Scientists are now struggling to create 113 and 114. How many elements can they add to the periodic table?
The Evolution of the Periodic System
From its origins some 200 years ago, the periodic table has become a vital tool for modern chemists
The Oort Cloud
On the outskirts of the solar system swarms a vast cloud of comets, influenced almost as much by other stars as by our sun. The dynamics of this cloud may help explain such matters as mass extinctions on Earth
Thermophotovoltaics
Semiconductors that convert radiant heat to electricity may prove suitable for lighting remote villages or powering automobiles