Feature

Earth’s Early Heat Found Higher than Now

Nature Note

New Ideas and Gadgets

Doctors Are Reading

Front Matter

U.S. Advances in Space

Gauge Measures Very High Altitudes

Saturn’s Camera System Most Elaborate Ever

Flares Menace Astronauts

Avoid Lethal Protons for Best Protection

More Armor Suggested for Moon Spacesuits

Mars ‘Air’ Found Thinner