For some of the 200,000 people each year who suffer pain severe enough to require lower-back surgery, a new solution has arrived. The Charit Artificial Disc is expected to receive FDA approval for degenerative disc disease by the end of 2004, making it the only artificial spinal disc available in the U.S. “This is the first major breakthrough in back surgery since the 1940s,” says orthopedic surgeon Richard Guyer of the Texas Back Institute in Plano.

$150 billion Amount the U.S. spent on HIV/AIDS between 1982 and 2004


$100 billion Cost to date of the International Space Station


$120 billion Estimated amount the U.S. has spent on the war in Iraq


850,000 Estimated number of people infected with HIV in the U.S.


25 Estimated percentage that are unaware of their infection


7 Percentage of female AIDS patients in the U.S. in 1986


26 Percentage of female AIDS patients in the U.S. in 2002

An ingenious new device could lead to an eye implant that restores sight to the blind.
This summer, physicist Mark Peterman and his Stanford University colleagues reported that they had constructed an artificial stand-in for photoreceptors, eye cells that register incoming light and dispatch chemical signals to relay that information to the brain. Their prototype is a one-square-

Dept.: You Built What?!
Tech: Homemade jet power
Cost: $10,000
Time: 10 days
Practical | | | | | Popcorn

By 1948 the bridge-and-skyscraper-style Erector Set had been around for 30 years. But the newest of the construction kits came with crank-powered motors and wheels, enabling kids to fashion walking robots like the one we featured on our cover. And somewhere in the ancestry of the Roombatoday's roaming, saucer-shaped robo-vacwas the Electrocar, which reversed direction when its spring-loaded bumper struck a wall. A child-size vacuum cleaner was also on our 1948 gift list.

At press time, no new launch date had been set, but if you’re following Swift closely or have an insatiable love for exotic astrophysical phenomena, you might enjoy a little tune written and performed by an a cappella group known as the Chromatics. Here’s an excerpt from the aptly titled “Swift Song,” concerning the function of the observatory:


Swift is the satellite that swings/
Onto those brightly bursting
things/
To grab the multi-wavelength
answer to what makes them glow.

The average wristwatch gains or loses about one second every few days, and undoubtedly, few of us notice the difference. But marking time accurately is crucial to some modern technologies. Atomic clocks—which base their ticks on the oscillations between the nucleus of an atom and its surrounding electrons—enable GPS navigation and ensure the proper timing of space probe launches and landings.

He still lacks a lower set of teeth, but a German man who had his jaw removed during a painful battle with mouth cancer just received a replacement. What makes his story unusual, however, is how his jaw was created. The risk of infection and the patient’s medication prevented doctors from taking the standard approach—constructing a substitute out of bone material grafted from other parts of his body. Instead surgeons at the University of Kiel in Germany grew a new jaw in the man’s back. Here is the simplified recipe.

American astronomer Fred Whipple, known to friends as Dr. Comet, died in August at the age of 97. Whipple is best known for positing in 1950 that comets are not loose clouds of dust and particles, as was widely believed, but hunks of ice embedded with rocky debris. The so-called dirty-snowball theory remained controversial until 1986, when a European spacecraft photographed the icy core of Halley’s comet and vindicated Whipple.

Now it’s really serious: Global warming could endanger champagne. French physicist Grard Liger-Belair, author of the forthcoming book Uncorked: The Science of Champagne, says that changes in the climate of the Champagne region of France could affect the local grapes. Warmer weather would boost photosynthesis in the leaves of the vine, producing added sugars, which migrate into the grape. This would reduce the acidity in the grapes and, as a result, disturb champagne’s delicate taste.