THE TOP SCIENCE OF 1997

1 OUR FAVORITE MARTIAN All eyes were on Mars this summer as NASA's Pathfinder lander and its Sojourner rover beamed home spectacular pictures of the Red Planet and introduced Earthlings to rocks with names like Casper and Scooby Doo. Sniffing out the chemistry of both the rocks and the soil, the rover helped confirm scientists' suspicion that Mars was once a warm, wet place, possibly able to support life. After four months of work, the lander and rover succumbed to Mars' punishing cold. Now and then, however, when the sun is high in the Martian sky, the rover may stir, toddling aimlessly as it waits for earthly signals that will never come.

2 Best-Known Clone Embryologist Ian Wilmut made a big splash in the gene pool when he announced that he had cloned a sheep named Dolly. Though animals had been duplicated before, Dolly was the first ever created from an adult cell rather than an embryonic one, raising the specter that a human will one day follow in her hoofsteps.

3 Bravest New Family Faith and a fertility drug delivered seven healthy babies to Bobbi and Kenny McCaughey of Carlisle, Iowa. Ranging from 2 lbs. 5 oz. to 3 lbs. 4 oz., the famous infants will remain in the hospital through January. Having survived the attendant media circus, Mom and Dad are recovering at home with first child Mikayla.

4 Deepest Freeze A Georgia woman bearing twins seems like small news in a year that produced septuplets. For the unidentified mother, however, the babies came with the help of once frozen eggs--the first such birth in the U.S. If the technology catches on, other women could bank their eggs, making older moms almost as common as older dads.

5 Most Troubled Craft The space station Mir, once the crown jewel of Russia's space program, fell on hard times this year as a string of mishaps threatened to shut the ship down for good. But Mir stayed aloft. And NASA, which has been sending U.S. astronauts to the station since 1995, plans to stand by its Russian partner.

6 Brightest Light The heavens were lighted last spring by the magnificent Comet Hale-Bopp, which whizzed within 120 million miles of Earth. Countless people turned out and craned up to see it--among them 39 members of the Heaven's Gate cult who took the comet as a sign that it was time to take their lives. That they did, leaving a dark blot on a brilliant event.

7 Most Dangerous Diet The fen/phen fad flamed out when doctors found that taking a mixture of the appetite suppressants fenfluramine and phentermine can cause permanent heart-valve damage. As the number of cases mounted, the FDA asked manufacturers to recall fenfluramine and the chemically related medication Redux.

8 Biggest About-Face In January the National Cancer Institute sparked a fire storm when it did not recommend that women in their 40s have annual mammograms. In March it reversed itself, endorsing the tests. With 1 out of 8 women likely to contract breast cancer, the turnabout looks medically and politically smart.

9 Tardiest Admission Thirty-three years after the Surgeon General first issued his warning, a cigarette company admitted that smoking causes cancer. As part of a legal settlement, the comparatively small Liggett Group also conceded that tobacco companies have aimed pitches at teenagers--a charge its bigger brethren still deny.

10 Damnedest Plague In 1996 it seemed unimaginable that HIV infected 8,000 people each day, as health officials calculated. But the true infection rate, new studies show, is nearly double that. According to United Nations figures, 1 in 100 sexually active adults between the ages of 15 and 49 is now living with HIV or AIDS.