If one were to judge by recent headlines, science did not approach the end of the millennium on a stellar note. Hopes of new revelations about the Red Planet were dashed when three probes--Mars Climate Orbiter, Deep Space2 and the Mars Polar Lander mysteriously went silent. And the Hubble Space Telescope had to shutter its eye on the distant cosmos when a gyroscope failed, pending a repair mission by the Space Shuttle.

But those events, as saddening as they were, are only part of the picture. Looking back over the final year of the 20th century, it is clear that 1999 was far from a bust. Nearly all fields had their smattering of breakthroughs, underscored by the steady accumulation of knowledge.


Despite the setbacks, spacecraft continue to probe the solar system and plumb the cosmos. And there was no shortage of speculation on ways to go to space, from air-breathing engines and space balloons to ultralight sails. Scientists continued the debate as to whether robots or humans should explore space in the first place, and considered how humanity might make money among the stars. Here on Earth, Scientific American compiled a Web guide to exploring other worlds.

To that end, colonizing Mars remained a distant goal. The Mars Global Surveyor, launched in 1996, at last completed the first detailed maps of the Martian surface this year. They reveal an exotic and extreme landscape that makes our home planet look pretty bland by comparison. The spectacular Martian scenery includes a six-mile-deep crater that could swallow half the U.S. and a dead volcano that towers to 17 miles.

The spacecraft also sends back daily weather reports which indicate that Mars is far from being a dead world. Its camera captured huge dust devils--much like our tornadoes--and provided evidence that the sand dunes on Mars are still being shaped by winds. Pictures of the Northern polar regions revealed watery stormclouds that mark the arrival of fall. And recently, researchers analyzing the planet's topography reported convincing evidence that a flat plain does, indeed, mark the site of an ancient sea.

After having its mission extended for two years to observe Jupiter's moons, the intrepid Galileo spacecraft successfully completed a risky flyby of Jupiter's turbulent moon, Io. Sailing just 380 miles above the surface, it returned some of the sharpest images yet of the most volcanically active body in the solar system. The new pictures, which were released by NASA on November 19, revealed a fiery landscape swept with colossal lava flows, vast lava lakes, towering and collapsing mountains and more than 100 active volcanoes.

Charting individual planets aside, other astronomers continued their efforts at mapping the entire universe, hoping to answer the question of whether space is finite.

This past year was also a prime time for space historians. July 20 marked the 30thth anniversary of the first manned Apollo landing on the Moon, when Neil Armstrong, his voice crackling from the speakers at NASA's Mission Control in Houston, said simply, "The Eagle has landed." And the ill-fated and controversial space capsule Liberty Bell 7 was raised from its watery grave almost exactly 40 years after it sank in the Atlantic Ocean, having carried the first astronaut, Gus Grissom, in a historic first orbit of the earth.

For its part, the Hubble Space Telescope continued to send back a stream of spectacular images for much of the year. Among its more intriguing findings was that the universe is apparently rife with "gravitational lenses," which were predicted by Albert Einstein in 1936. These distortions, created by massive objects in space (galaxies and black holes), create mirages of even more distant objects in the cosmos.

In addition, Hubble got some company in orbit with the perfect launch in July of Chandra. This NASA "Great Observatory" sees the turbulent cosmos in the x-ray wavelengths. Less than a month after reaching its final orbit, Chandra began sending back stunning images of gigantic stellar explosions and powerful x-ray jets blasting 200,000 light years into intergalactic space from distant quasars. In mid-December the orbiting telescope captured a rare glimpse of x-radiation from the early phases of a supernova, one of the most violent events in nature. Although more than a thousand supernovae have been observed by optical astronomers, the early x-ray glow from the explosions has been detected in less than a dozen cases.


Another orbiting eye on the cosmos, the Compton Gamma-Ray Observatory, which was launched in 1991, recorded the transient afterglow of a mysterious gamma ray burst. GRB 990123, was one of the most energetic and the most closely observed gamma bursts ever--emitting in less than a few tens of seconds a blast energy that might correspond to ten thousand times the energy released by our sun over the past five billion years. Like the flashbulbs of paparazzi, gamma ray bursts pop off all the time in the universe; about one a day but their origin remains elusive.

But the work of ground-based astronomers was not overshadowed by the images beamed from orbit. In June, astronomers unveiled the first images from the new Gemini North Observatory near the summit of Mauna Kea in Hawaii. They are some of the sharpest infrared pictures ever produced, thanks to the 8-meter wide telescope's immense resolving power, which at times tops that of the Hubble Space Telescope. Meanwhile, astronomers at the Wide Field Imager, a 67-million pixel digital camera at Europe's La Silla Observatory in the Chilean Andes released some stunning shots of two distant nebulae. And the Keck Telescope, also on Mauna Kea, recorded images of a curious star, known as Wolf-Rayet 104, which spews out a jet of superheated gas like a cosmic lawnsprinkler.

In addition, our place in the cosmos began to look a little less lonely as astronomers continued to spot telltale wobbles in distant stars that indicate the presence of planets, including the discovery that a nearby star known as Upsilon Andromedae, quite like our Sol, sports a trio of planets. In December, a team of astronomers searching the galaxy with the Keck Telescope in Hawaii reported the identification of six new planets orbiting nearby stars, bringing the total found to 28. All the extrasolar planets have been found within the last five years. And these newcomers probably share a trait of our own nine neighbors: migration

Earthbound astronomers--amateur and professional alike--got a rare treat when a total solar eclipse swept across Europe in August. In November, the Leonid meteor shower produced a spectacular fireworks display for sky watchers.

Researchers turned up some tantalizing clues to the origin of life. At the American Physical Society meeting in March scientists reported that our makeup of complex molecules based on carbon and hydrogen is no fluke and that precursors to terrestrial life's distinctive chemistry apparently abound in distant space. Indeed, many organic molecules churn in far off clouds of dust and gas in our cosmos.


Then, of course, there is water, which accounts for more than 70 percent of the weight of living organisms and exhibits an array of unique properties that make it the stabilizing influence on global climate and the key to life itself. The key, it seems, lies in the interaction between the bonds that hold the atoms in the water molecule together and the much weaker bonds, known as hydrogen bonds, that are the glue holding groups of water molecules together.

Another mystery--when oxygen made its debut as a leading gas in Earth's life support system--was pushed back from 1.2 billion years ago, the time when the earliest land-based life appears in the fossil record. Researchers from the Astrobiology Research Center at Pennsylvania State University presented evidence that there was an abundance of oxygen on Earth as long as 2.3 billion years ago.

And some of our ideas about evolution underwent revisions in 1999. A remarkably well preserved hominid skeleton, some 15 million years old, was unearthed in Africa in 1993. Now, analysis of the bones of KNM-TH 28860 is helping paleontologists prune out the hairy Miocene apes from those from which we are descended. And there is more evidence that Neanderthals were not a separate species from modern man but probably close cousins who weren't so very different after all.

Evidence from a cave in Vindija, Croatia indicates that Neanderthals and modern man must have coexisted in central Europe for at least six millennia. Skulls unearthed there are between 28,000 and 29,000 years old, compared with the most recent findings of 33,000 to 34,000 years for Neanderthal remains found in Spain. More intriguing, rather than being blood enemies the two groups apparently traded with each other--and may even have interbred.

It also appears that humans were writing words with the modern alphabet much earlier than previously thought. A recently discovered inscription on a rock in a desert valley of what is now southern Egypt indicates that the first alphabet -- from which all modern alphabets have evolved -- was probably invented in Egypt, not, as previously thought, in the Levant Region, what is now Syria, Lebanon and Israel. Until now, scholars believed that the forefather of written Hebrew, Arabic, Greek -- virtually all alphabets, including ours -- was invented in the 1700s B.C. The inscriptions in Egypt now point towards an origin in the 1900s B.C.

Dinosaurs, too, underwent a little rethinking. In the past few years, a number of paleontologists have reported skeletonal evidence that saurians were warm blooded, nurturing, and the probable ancestors of modern birds. But that cuddly theory may not fly. With a few bones of his own, vertebrate paleobiologist John A. Ruben of Oregon State University contends that dinosaurs are more akin to komodo dragons than cockatiels.

A puzzle of flight--what keeps bumble bees aloft--was solved by Michael Dickinson, an assistant professor of integrative biology at the University of California at Berkeley. He built a scaled up set of robot wings that duplicated insect flight in a bath of mineral oil and measured the forces they generated. But the most impressive flight of the year was clearly the around-the-world balloon saga of Bertrand Piccard and Brian Jones. During/ the midmorning of March 21, they soared into the history books when their balloon, Breitling Orbiter 3, sped at 130 miles an hour at an altitude of 36,000 feet over an invisible finish line at 9 degrees 27 minutes west longitude in Mauritania. The next challenge? Maybe circumnavigation aboard modern zeppelins.

Biotechnology continued to be controversial. Rumors were rife that cloned humans were imminent. In a special issue of Scientific American, several scientists pondered just out how near a bionic future--one filled with head transplants, muscle-building vaccines, machine-enhanced minds and cloned people--really is. Sounds too fantastic? Consider that scientists at Princeton this year created of a strain of super smart mice by manipulating a single gene.

More immediate issues over bio-engineering included the ongoing debate over genetically modified crops. Increasingly vociferous opponents began to challenge the wisdom of altering food crops with pesticide-producing genes in Europe and the United States.

Advanced imaging and modeling techniques gave scientists their clearest look yet at important biological and chemical processes. Researchers at Arizona State University published the first true images of atomic orbitals in a crystal called cuprite. Said lead author J.M. Zuo: "It's direct, experimental proof of the quantum model." And close up pictures of ribosomes are helping explain how these tiny organelles, like highly efficient factories, manufacture all of the proteins for sustaining life from simple genetic templates. Another puzzle--how proteins fold into elaborate shapes that influence their function is being tackled by a supercomputer running a mathematical algorithm developed by Jonathan King of Massachusetts Institute of Technology and Sorin Istrail of Sandia National Laboratories. So too, advanced imaging is enabling researchers to better visualize human embryos.

Other researchers are trying to harnass the machinery of cells to produce a new generation of tiny machines that could do useful work in the body. Indeed, atomic engineering has come a long way of late. Scientists at Cornell University patterned a molecular scale engine after those in cells that wave bacterial cilia or transport energy across membranes. The scientists found their molecular stator and rotor in the form of an ubiquitous molecule, the enzyme ATPase.

In electronics and computing, too, miniaturization of components continues to drive the information and communications revolutions. Using the new methods of micromachining, which borrow technology for making computer chips to carve out and build up microscopic structures on silicon wafers, Peter Gammel and his colleagues at Bell Labs/Lucent Technologies reduced three of the critical devices of a cell phone to Lilliputian size that will allow all the components of a phone to be constructed on a single chip. And other Bell Labs researchers recently produced some of the smallest and fastest transistors ever, proving that for now , at least, Moore's Law marches on.

All the while, the race to bring high speed data to the home-- be it by cable, twisted pair, optical fiber, satellites or wireless technology--continued. And soon, whichever modes win out will give us all better home access to the second-generation web, XML pages and improved search engines.

So, the torrent of new and exciting data continues to stream from the laboratory. Indeed, so much so that some scientists are worried about their ability to sort through and make sense of all the new information. For example, each year the detectors at the CERN particle collider in Switzerland record 1 petabyte of data--more than 1,000 times all the words in the Library of Congress. But others are already hard at work preparing for the new millennium. They are creating huge scalable databases, housed on computers around the world and connected by the Internet. Any researcher with access to the World Wide Web will be able to query these servers with specific searches and have the graphical data appear on their computer screens in seconds.

So stay tuned. If our pages are any indication, the best of science is yet to come. Renowned physicist Steven Weinberg had predicted the unification of physics by 2050, and we can be certain of learning a great deal of unexpected science in the century to come.