In the 50 years since the launch of Sputnik, the 'traveling companion's' legacy has been far-reaching. Sputnik ignited a dangerous game of one-upmanship between the world's two superpowers, spurred the development of technology capable of placing humans on the moon, and it heralded a new age of discovery that would take humans, or at least their robotic emissaries, to the farthest reaches of the solar system. The follow-on effects Sputnik has had on science are as follows:

Van Allen Belt

Shortly after Sputnik's launch, American scientists led by James Van Allen discovered a ring of high energy particles encircling Earth. The finding was arguably the first major scientific discovery of the space age and confirmed Earth had a magnetic field shielding it from the solar wind. Scientists now know there are actually two radiation belts, both of which can be hazardous to satellites and astronauts.

Humans in space

By launching into space and returning back safely, Yuri "Cedar" Gagarin proved that humans could survive in space. Scientists had previously speculated the human body could not function properly in a zero-G environment or survive bombardment by cosmic particles. Since Gagarin, 462 other lucky people have flown in space.

To the Moon

Not to be outdone by the Russians, President Kennedy promised in 1961 that the United States would have a man on the moon before the decade was through. Neil Armstrong made good on that boast when in 1969 he set foot on the lunar surface and took "one small step for man, one giant leap for mankind."

Instant communication

If our world seems smaller today than it did a few generations ago, it is largely due to advances in communication and information technology made possible by orbiting satellites. Humans can now know exactly where they are; communicate with each other across continents and oceans; and control robots on distant worlds.

Robotic scouts

Sputnik would be proud. Whereas it could only orbit Earth, its robotic descendents have explored nearly all the major worlds and moons of our solar system. They've flown through the tails of comets, performed kamikaze crashes into asteroids, and some are on their way to leave our solar system altogether.

Our strange universe

Exploding stars, colliding galaxies, shrinking planets, ravenous black holes, and much more have been vividly revealed to human eyes only since space-based imaging became possible. Documenting the cosmos in X-rays, visible light and other wavelengths of the electromagnetic spectrum as can only be done best from above Earth's atmosphere, Space Age technology has revealed our universe to be a much stranger place than scientists had ever imagined.

Answering age-old questions

Humans had studied the heavens for centuries before Sputnik, but astronomy didn't become a precision science until the space age. COBE provided the first accurate measurement of the cosmic microwave background and established the Big Bang Model as the premier theory for how our universe began. Its successor, WMAP, dated our universe to 13.7 billion years old - ending a decades-long guessing game - and found evidence for totally mysterious dark matter and dark energy, opening new cans of worms for future space-based observatories to look into.

ICBMs

Sputnik's legacy isn't all rosy. It also heralded an age of paranoia, when people lived in fear that they could be targets of missiles hurled from across the world. The same technology that launched a satellite into space could also be used to chuck nuclear warheads at your enemies from a continent away.

Blue marble

The space age marked the first time humanity had ever glimpsed its world in full. Images of Earth suspended in space like a "blue marble" conveyed our planet's fragility and mankind's oneness in ways that words could not. One such image, taken by the crew of Apollo 17 in 1972, is one of the most widely distributed images in history.

The Phoenix spacecraft exposed bright white crumbs at the bottom of a trench while digging near Mars' North Pole earlier last week. The bits disappeared in new photos sent back on Thursday, June 19 convincing scientists that the magic act was evidence of ice that vaporised after being exposed to the sun.

"The fact that there's ice doesn't tell you anything about whether it's habitable," chief scientist Peter Smith of the University of Arizona said during a teleconference from Tuscon. To judge whether the Martian polar environment could be hospitable, scientists are using the spacecraft's instruments to study minerals in the soil and ice for hints of carbonates and sulfates, which are formed by the action of liquid water.

Preliminary results from an experiment that baked a soil sample in one of Phoenix's test ovens failed to yield evidence of water. Mars today is arid and dusty, constantly bombarded by radiation and with no apparent trace of water on its surface. But carvings of channels and gullies on the Martian surface suggest a wetter past. Some scientists speculate that water may have evaporated into the atmosphere and the rest trapped beneath the surface in the form of ice.

"The holy grail is to find water near the surface of Mars," said astrobiologist Mitch Sogin of the Marine Biological Lab in Woods Hole, Mass., who is not part of the mission. Phoenix's latest discovery is not a total surprise. In 2002, the orbiting Mars Odyssey spacecraft spied evidence of a reservoir of frozen water near the planet's poles. Phoenix, which landed on May 25, is the first robotic craft to reach out and touch it.

Scientists not involved in the mission said the Phoenix team makes a compelling case for the presence of ice. "It's not unexpected, but finding it is different than predicting it," said Bruce Jakosky, an astrobiologist at the University of Colorado at Boulder. "Everybody expected the ice to be there. That's why Phoenix went there in the first place." The bright chunks seen in the Martian soil vanished in images taken on Thursday, May 19 of a trench where they were seen four days earlier. Scientists had debated whether the chunks were salt or ice, but settled on frozen water since salt would not disappear.

"We have found the proof that we've been seeking," Smith said. Smith said the ice, which appeared to be pure, was found two inches deep in the trench. Digging in another trench, Phoenix hit a hard surface believed to be an icy layer, which will also be tested. The big question is whether the ice ever melted and remained stable long enough as a liquid. "If so, one of the requirements is satisfied for life as we know it," said Kenneth Nealson, a geobiologist at the University of Southern California, who had no role in the mission.

Scientists must start dumping carbon dioxide into the deep ocean to see whether it provides a safe way of tackling global warming, a leading expert on climate change has said.

Wallace Broecker, of the Lamont-Doherty Earth Observatory at New York's Columbia University, says experiments must be carried out 'promptly' and has called on environmental campaigners to drop their opposition to such schemes. Experts have said carbon dioxide stripped from the exhaust gases of power stations and dumped in deep water would stay there for hundreds of years, but there is concern about the impact on marine life. Broecker says: "While we know enough to say with confidence that deep ocean disposal of CO2 is certainly feasible, unless small-scale pilot experiments are conducted, information necessary to assess the impact [on sea life] will remain obscure. It is my view that a series of experiments involving one-tonne quantities of CO2 should be conducted."

He says such injections of the gas could be made from deep-sea drill ships, and monitored to see how it dispersed and affected marine life. Otherwise, he warns, the gas could be dumped in future with no idea of the consequences. "If marine disposal proves to be economically favourable and if push comes to shove, forces ... will likely intervene and deep-sea disposal will commence without adequate testing and evaluation." Unlike most carbon capture and storage schemes, which aim to trap the gas and pump it into underground saltwater reservoirs or empty oil and gas fields, deep-sea storage would release the carbon dioxide directly into the water. Only very deep water would be suitable as great pressures are needed to stop the gas simply leaking back to the surface. At depths greater than 3,500m, scientists think the gas would be compressed into a slush that would settle on the sea bed. That rules out shallow seas such as the North Sea, but makes the Pacific Ocean a prime candidate -- particularly as underground reservoir storage sites for carbon dioxide in the Pacific region could be vulnerable to earthquakes.

Broecker says 480bn tonnes of carbon dioxide could be safely dumped directly into the waters of the deep Pacific, equivalent to the carbon pollution from about 16 years of the world's current fossil fuel use. Worms and other organisms on the sea bed directly beneath the storage site would be killed, Broecker admits, but he says the impact would be "trivial" compared to that of the fishing industry. Other experts have said the injected carbon dioxide could damage larger marine life including fish because the gas will dissolve in the seawater and make it more acidic.

Small amounts of CO2 have been injected into deep water off the California coast but there have been no large-scale experiments to test the concept. A planned pilot scheme off Hawaii was scrapped in the late 1990s after protests from local people and environmental groups. Greenpeace remains implacably against such experiments. Broecker says: "I am in full sympathy with those who claim that the benthic world [the lowest level of a body of water] is likely a fragile one. Hence, before we poke it with CO2, we should do our homework. Therefore, I challenge Greenpeace to relax its stand and allow pilot CO2 injections to proceed." But Bill Hare of Greenpeace said: "The urgency of reducing emissions of CO2 has never been greater. But just as with an emergency in a heavy passenger jet, the crew should never rush in to hasty actions that will ultimately make a very bad situation a lot worse. Ocean disposal of CO2 is one such option. The position of Greenpeace and of other groups opposed to this option was based on research into the effects of ocean disposal of CO2."

The idea of an optical telescope on the moon gets astronomers understandably excited. With no atmosphere to blur incoming light, a lunar telescope could capture razor sharp images at magnifications that would not be possible with terrestrial 'scopes. But a major stumbling block - the cost of getting telescope construction materials to the moon - has derailed the idea in the past. Now, however, scientists at NASA may have stumbled upon a low-cost raw material to fabricate the telescope from - moon dust.

Peter Chen, at NASA's Goddard centre, says that to make a mirror that dwarfs anything on Earth, just take a little bit of carbon, throw in some epoxy, and add lots of lunar dust. "We could make huge telescopes on the moon relatively easily, and avoid the large expense of transporting a large mirror from Earth," explains Chen. "Since most of the materials are already there in the form of dust, you don't have to bring very much stuff with you, and that saves a ton of money." Chen and his co-researchers presented their mirror-making technique in a session at the 212th meeting of the American Astronomical Society in St. Louis.

Chen and his team stumbled upon the new dust-based material when they mixed carbon nanotubes and epoxies (glues) with crushed rock that had the same composition and grain size as lunar dust. They discovered to their surprise that they had created a very strong material with the consistency of concrete that can be used instead of glass to make mirrors of any size. They next applied additional layers of epoxy and spun the material at room temperature. The result was a 12-inch-wide mirror blank with the parabolic shape of a telescope mirror. All achieved with minimal effort and cost, according to Chen. "After that, all we needed to do was coat the mirror blank with a small amount of aluminum, and voilà, we had a highly reflective telescope mirror," said co-researcher Douglas Rabin.

"Our method could be scaled-up on the moon, using the ubiquitous lunar dust, to create giant telescope mirrors up to 50 meters in diameter." Such an observatory would dwarf the largest optical telescope currently operating, the 10.4-metre Gran Telescopio Canarias in the Canary Islands. Chen says that with a lunar-based 50-metre telescope, astronomers could record the spectra of extrasolar planets and detect atmospheric biomarkers such as ozone and methane. More tantalisingly, two or more such telescopes operating in tandem could take direct images of Earth-like planets around nearby stars and look for brightness variations that come from oceans and continents.

Building on earlier work that found evidence of human viruses in deceased chimpanzees, a new study by Virginia Tech researchers has confirmed that chimps in Tanzania's Mahale Mountains are becoming sick from a variant of a human paramyxovirus. While the findings, reported in the American Journal of Primatology, demonstrate that the respiratory disease can spread from humans to chimps, the researchers are cautious about identifying the exact transmission route. "Although evidence increasingly suggests that infectious diseases may be transmitted from research teams and eco-tourists to endangered great apes, we believe that this is still a bit of a leap and more research must be conducted in order to establish a comfortable level of proof," said Virginia Tech's Dr Taranjit Kaur.

"Exactly where this virus has come from and the specific route of transmission remains unclear at this time," said Kaur, but she admits that mounting evidence suggests a linkage between visiting scientists and tourists and the viruses that are threatening the endangered chimpanzee population.

Arocket carrying a U.S.-French ocean-monitoring satellite lifted off early Friday, June 20 from the central California coast.

The Delta 2 rocket blasted off at 12.46 am after what officials called a 'remarkably smooth' countdown. Video showed the satellite separating from the rocket moments after the launch. "We can see the spacecraft gently drifting away," said the project's telemetry manager, Mark Lavigne.

The satellite, called Ocean Surface Topography Mission-Jason 2, will use a radar altimeter to precisely measure the height of the ocean surface, which changes depending on temperature. The data will be used to monitor effects of climate change on sea level and to improve global weather, climate and ocean forecasts, NASA said. Such observations began in 1992 with a spacecraft dubbed TOPEX/Poseidon and have continued with the current Jason 1 satellite. The two Jasons will fly in tandem.