Rignot used radar data taken between 1992 and 1996 by two European satellites, ERS-1 and ERS-2, to generate interference patterns that are sensitive to small vertical movements. These patterns provide information on the velocity of the ice – how fast it is creeping towards the bay – and the hinge point – the position on the glacier at which ice moves from resting on the bay bed to ice floating on the water. Recent measurements have suggested that the Pine Island glacier is melting at a much faster rate than other large ice shelves in the Antarctic. Researchers believed this was being caused by an influx of warm water from the Southern Pacific Ocean. Rignot’s latest work concludes that 76 ± 2 km3 of ice is being discharged into the bay each year, while only 71 ± 7 km3 is replenished from the Antarctic interior – which indicates that the glacier is shrinking at a startling rate. If this data does herald the start of collapse for the Antarctic ice sheet, water levels could rise by more than 5 m within a couple of centuries.
‘Idle’ machines look for ET
In the past similar approaches have been used to crack encryption codes or calculate the largest prime number, but this is the first time such a scheme has been used for analysing raw scientific data.
The system works by fooling the computer into running a screen-saver package called SETI@home every time the machine is idle. As soon as user returns to work, the program shuts down. As most computers are only used 8 hours a day, this gives the project 16 hours a day of computer time. The large number of machines used in the project will help SETI watchers to analyze smaller parts of the frequency spectrum more thoroughly than current SETI projects. The approach will also be ten times more sensitive than previous experiments.
So far the researchers have released Windows and UNIX prototypes of the software, and a Mac version is planned. Within the next six months the team hope to finish a more polished package that will also provide three different types of visualization of the experiment: science mode will describe the analysis taking place on the local machine and the significance of any results; sky progress mode will show what parts of the sky are being covered by the entire experiment, and summarize all the potentially interesting results found so far; and Earth progress mode will focus on the people participating in the experiment, with a view of the earth showing all the individuals and organizations currently participating. Once up and running, the experiment is expected to run for at least two years.
The shape of sonoluminescence
Sonoluminescence occurs because sound waves cause a bubble to expand and then collapse in a liquid. The bubble first expands to almost 10 times its original dimensions, and then collapses at supersonic velocities to a minimum diameter that depends on atomic forces in the bubble. At this point the implosion produces a flash of light and pulse of sound. The bubble then re-expands to its normal diameter.
Bruno Gompf and co-workers from the University of Stuttgart in Germany have successfully used a streak camera to study these rapid light pulses (Phys. Rev. Lett . 81 717). The trick was to take advantage of the predictable nature of single-bubble sonoluminescence (SBSL). As the bubble emits light at regular time intervals, the researchers could use a photomultiplier tube to activate the streak camera a fixed time after the previous light pulse. Based on the measurements of thousands of flashes, the average duration of a pulse was found to be 208 ps (±21 ps). This duration also appeared to be independent of temperature at fixed pressure and gas concentrations.
Gompf and co-workers also discovered that although the rise time of a SBSL pulse remains constant when the pressure is increased, the fall time increases. The team speculates that the fall time depends on the re-expansion rate of the bubble. Since the bubble takes longer to expand at higher pressures, more energy is converted to light, and hence the fall time of the pulse increases.
The myth of high-tech job creation
The report suggests that governments should move more university researchers onto short-term contracts to encourage mobility between academia and industry. It also recommends that scientists should rely on specific research grants rather than general research funding provided by institutions. Such a system already operates in the UK, US and Australia and has been very successful in transferring technology from academia to industry. An ageing scientific work force and a shortage of students choosing science are other problems, according to the report.
The report also highlights the recent decline in R&D funding, and the switch to more short-term and market-oriented research by industry. Any further fall in R&D investment – caused either by slow economic growth or decreases in government support for basic science – could create “adverse long-term consequences if current trends continues”, the report states. To combat declining industrial investment, the OECD recommends tax breaks for firms carrying out R&D and tax incentives for individuals undertaking training.
First American in space dies
Shepard was born in East Derry, New Hampshire, on November 18, 1923, and received a Bachelor of Science degree from the US Naval Academy in 1944. Before joining NASA, he flew as a Navy pilot. Shepard features in one of the most memorable images from the US space programme – he was the first golfer to play with a lunar handicap. Unfortunately the images of an astronaut playing golf on the Moon increased pressure on NASA to cut back the Apollo programme. Shepard later headed NASA’s astronaut office before retiring in 1974. Afterwards he became president of the Mercury Seven Foundation, a charity that awards science and engineering scholarships.
Black hole alert for astronomers
When a star explodes as a supernova, the remnants of the explosion can fall inwards to form a neutron star or a black hole. Neutron stars are easy to detect because they emit powerful radio waves. Black holes, on the other hand, are difficult to detect because they do not emit any radiation. They can only be observed by their effects on material outside the black hole. However, material falling into a black hole emits radiation before it is swallowed up by the black hole. Zampieri and co-workers have calculated the effect that the expanding cloud of hot hydrogen gas formed in the explosion has on this radiation. Initially the gas is dense and optically ‘thick’ at many wavelengths, which prevents light escaping. As the gas expands and cools, however, it becomes optically ‘thin’ and transparent at many wavelengths. This will lead to a characteristic bump in the light curve. Many astronomers think that supernova 1987A contains a black hole, especially since there is no evidence that it formed a neutron star. However, there is no evidence for the tell-tale bump in the light curve either. It is now thought that SN1987A is simply to bright for this effect to be observed ( http://xxx.lanl.gov/abs/astro-ph/9804122). That is why attention has turned to SN 1997D, which is the dimmest Type II supernovae observed to date. According to calculations, the bump should become visible to space and ground-based telescopes in the year 2000.
Falling objects: new twists on an old problem
Andrew Belmonte of the University of Pittsburgh, and Hagai Eisenberg and Elisha Moses of the Weizmann Institute of Science in Israel dropped thin strips of plastic, brass and steel in various liquids and filmed their motion with a high-speed video camera. The liquids used by the team included water, petroleum ether and a 40:60 mixture of glycerol and water.
Two distinct types of motion were observed: fluttering from side to side and tumbling. The transition between these two types of motion was governed by the Froude number of the system – the ratio of the time taken for the strip to fall its own length to the time taken for it to move from side to side. Froude numbers date back to 1874 when they were used in the study of ships.
Belmonte and co-workers noticed that the strips tended to flutter for Froude numbers below 0.67 (± 0.05), and to tumble for higher values, sometimes changing the direction in which they tumble. For higher still Froude numbers the strips tumbled in one direction only. The team were able to show that the drag experienced by the strips, rather than the viscosity of the liquid, was the key factor in determining the Froude number and hence the motion of the strips. The next challenge is to study how the flow of the fluid around the strip and the vortices created by the movement of the strip influence the drag and therefore the motion.
Satellite email on the cheap
Satellites have been used to provide email access in isolated regions of the world for at least eight years. Until now, however, all such systems have relied on bulky equipment costing tens of thousands of pounds, or on commercial satellites with high usage fees. For example, the British Antarctic Survey uses IMARSAT-B, a commercial satellite, to keep in contact its researchers working in the Antarctic.
LLMS now offers a much cheaper alternative. “We expect the terminals to cost 1000 ECUs, ” says Erik Ceuppens of SAIT Systems. The LLMS service is currently undergoing system checks and SAIT hopes to have it up and running by the end of the year. If it proves successful there are plans to launch a more powerful LLMS platform on a dedicated satellite in mid-2000. ESA researchers, meanwhile, have plans to use LLMS technology in remote sensing applications such as environmental monitoring.
The service is likely to face competition from the new range of cheap satellite telephones from Iridium (which starts on the 23 September), SkyBridge (2001) and Teledesic (2002).
Big boost for British science
The government is to give the UK’s research councils an extra £400 million for new projects and £300 million to improve the infrastructure in Britain’s universities. The Wellcome Trust, a medical research charity, is provide a further £300 million for universities. The trust will also contribute £100 million towards the construction of a third-generation synchrotron radiation source in the UK.
According to the government, the extra £400 million for the research councils will be “for priority areas like life sciences”, while at least half of the infrastructure funds will be used to support research in the biomedical sciences. The rest will go on “other high priority areas, including the underpinning disciplines of chemistry, engineering, mathematics and physics.”
Under existing plans the UK science budget was earmarked to remain at £1349 million from this year through to 2001/2. The new government money will increase the science budget to £1474 million in 1999/2000, £1588 million the year after, and £1659 million in 2001/2. The Wellcome Trust already spends some £250 million on research every year.
The pressure group Save British Science said: “This has been a good day for British science.”
Astronomers catch ‘planet-mania’
Greaves and colleagues used the SCUBA instrument on the James Clerk Maxwell Telescope in Hawaii to look at the dust around Epsilon Eridani. SCUBA operates at submillimetre wavelengths, where the glare from the central star is weak. The same instrument detected dust around three nearby stars in April. “If an astronomer could have measured what our solar system looked like four billion years ago, it would look very much like Epsilon Eridani looks today, ” said Benjamin Zuckerman, one of the team. “What we see looks just like the comet belt on the outskirts of our planetary system, only younger, ” said Greaves. “It’s the first time we’ve seen anything like this around a star similar to our Sun. In addition, we were amazed to see a bright spot in the ring, which may be dust trapped in orbit around a planet.” If the image really is cometary debris, the number of comets orbiting the star must be 1000 times larger than in the solar system. Kalas, however, argues that there is only “weak support” for some of the previous claims by astronomers that dust clouds and central cavities indicate planetary formation. Our experience and theories of planetary formation are limited to solar-type stars, says Kalas, not to massive and more luminous stars such as those reported by some groups. “We cannot uniquely identify the cause of the dust blobs and dust cavities, ” he concludes Kalas reserves his most stringent criticism for the group which claims to have
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