Ocean temperature changes trigger glacial melt
    A radar scientist tracking the rapid recession of a West Antarctic glacier says that the glacier’s position on the continent provides solid evidence that changes in ocean temperatures can trigger the collapse of an ice sheet. Eric Rignot of the Jet Propulsion Laboratory in Pasadena, Calif., published work in the July 24 Science tracking the changing hinge line of the Pine Island Glacier over nearly four years. Using radar interferometry data taken by the European Space Agency’s Earth Remote Sensing Satellites (ERS-1 and 2), he found that the Pine Island Glacier — an ice stream of the West Antarctic Ice Sheet — retreated inland at about one kilometer a year between 1992 and 1996.
    All glaciers experience basal melting, but Rignot says the glacier’s fast retreat in this case is evidence of excess basal melting. The excess melting, he found, caused the glacier to retreat 1.2 ± 0.3 kilometers per year from its hinge line — the transition between grounded ice and floating ice — at Pine Island Bay, which flows into the Amundsen Sea on the southwest side of the continent. Overall, the glacier thinned 3.5 ± 0.9 meters per year and retreated five kilometers in 3.8 years.
    Citing work published in 1996 by Stanley Jacobs, Hartmut Hellmer, and Adrian Jenkins, Rignot says an influx of relatively warm ocean waters from the southern Pacific apparently fuels high basal melting of the Pine Island Glacier. Work by Jacobs and colleagues, as well as by Terence Hughes of the University of Maine, suggests that basal melting is sensitive to changes in ocean conditions and that the Pine Island Glacier, located far south on the continent, is particularly sensitive to warmer waters. Rignot says his inferred rate of ice thinning could be evidence of excess basal melting caused by an increase of only 0.1º Celsius in ocean temperature. The glaciers are tremendously sensitive to ocean temperature, he says. “The large melt rates recorded near the hinge line imply that Pine Island Glacier is even more sensitive to ice-ocean interactions than was inferred from the 1994 survey [by Jacobs and colleagues] of ice-front conditions.”

A history of collapse
    A team of researchers led by Reed P. Scherer of Uppsala University in Sweden reported in the July 3 Science that, based on glacial sediment samples recovered from beneath the West Antarctic Ice Sheet, the massive ice sheet had collapsed in the late Pleistocene. At least two ice shelves on the continent have retreated recently — the Wordie Ice Shelf and the Larsen Ice Shelf on the Antarctic Peninsula at the northwest end of Antarctica. The retreat of the Pine Island Glacier provides evidence in the south of the melting of the ice sheet, Rignot says. Also, the Pine Island Glacier sits in the main part of Antarctica. And unlike the Larsen Ice Shelf, warm air temperature does not factor into the melting of the Pine Island Glacier. “Something must be changing in the ocean,” he says. “We’ve always thought about ice-sheet collapse through mechanical instabilities or
drastic changes in precipitation or surface temperature. The case of Pine Island Glacier raises the issue that changes in ocean waters — for instance, changes in ocean currents could [alter] the temperature of the ocean waters surrounding the glacier — are a far easier way to trigger collapse of an ice sheet. That’s big news.”
    Previous research shows the glacier is vulnerable to climate change. Rignot attributes the glacier’s retreat to basal melting by warm southern Pacific Ocean waters. If excess melting, brought on by warmer temperatures in the southern Pacific Ocean, continues at the rate he calculates, the West Antarctic Ice Sheet could eventually collapse. Such a disintegration would raise sea level by several meters. “The retreat of Pine Island Glacier is so large that it is hard to imagine a clearer signal sent to us by the glacier for signaling [the ice sheet’s] imminent collapse,” he says. — K.B.
 

Retreat of the redwoods
    It takes a lot to down a redwood. These hearty giants of the forest have existed for millions of years. But the species hasn’t always been confined, as it is today, to the forests of China and North America. Once, redwoods dominated the landscape across North America, Europe, and Asia. Then they were brought down — “conquered,” apparently, by the pines they had peacefully co-existed with for 100 million years.
    “It’s one of the most dramatic transitions in paleobotany, and I wanted to know why it happened,” says Ben LePage, a geologist at the University of Pennsylvania. A description of LePage’s research and his explanation for the near-extinction of the redwoods were published in early July in New Scientist. LePage tells New Scientist, “The redwood design worked well for over 60 million years. What changed?”
    LePage focused his studies on Axel Heiberg Island in the Canadian Arctic. The island contains abundant evidence that 45 million years ago, its hills were covered in a lush temperate woodland, quite different from the arctic tundra of today. In some regions of the world, it’s easy to ascribe environmental and ecological transformations to plate tectonics. But here, the usual explanations for major climate change don’t apply so neatly. LePage took advantage of Axel Heiberg Island’s geography and unique environment to put together a picture of how the redwoods’ landscape was transformed. It’s a story of how geologic and oceanographic changes, along with some deep-rooted ecological associations, forced the mighty redwoods into submission.

Geologic factors
Axel Heiberg Island has moved barely two degrees in tens of millions of years, tectonically speaking. Oceanographically, however, there have been enormous changes. Between 70 and 45 million years ago, ocean circulation patterns of the proto-Gulf Stream kept temperatures in the north Atlantic much higher than they are today. “Because the land masses had a different shape then,” New Scientist reports, “ocean circulation pushed tropical waters much further north.” But rifting in the sea floor between 55 and 33 million years ago created deep channels, linking the waters of the Arctic and Atlantic Oceans, which
had been separated by the Greenland-Fennoscandian Ridge. These channels “allowed cold, dense water from deep in the Arctic Ocean basin to drain into the North Atlantic.” It took less than a million years for this transition to occur. Ocean circulation patterns changed, and the climate rapidly cooled. Says LePage, “For the forests on Axel Heiberg, the effects would have been catastrophic. The entire ecosystem probably collapsed in a short space of time.”
    Other geological changes that would force the redwoods to retreat were also occurring — the rise of the Rockies damaged the species in North America, while the subsequent rise of the Himalayas adversely affected the populations of redwoods in Asia. LePage explained to New Scientist that the redwoods were effectively trapped, “unable to colonize or survive at the new mountains’ higher altitudes. … Tracks of redwood forest would simply have shriveled away.”
    The Himalayan growth caused worldwide climate change as well, cooling the globe over a period of 55 million years. This, too, would have sped up the redwoods’ demise. LePage says that these explanations for the contraction of the redwoods’ range are acceptable. But they don’t answer all of his questions. Since the redwoods were able to co-exist with the pine species for 100 million years — evident from the fossil plant records on Axel Heiberg Island — LePage couldn’t understand why the pines eventually replaced redwoods as the dominant trees in the north. “There had to be some kind of Achilles heel that no one else had thought of,” he says. He looked to the roots for the answer.

Deep-rooted associations
    For 12 years, LePage and his colleagues worked on Axel Heiberg Island, excavating a remarkable deposit of leaves, roots, and tree stumps — not fossilized, but mummified, incredibly preserved by burial. The deposit has helped the scientists reconstruct the island’s ecology, and has led LePage to the key to the redwoods’ fall. Pines and redwoods, like most plants, have mycorrhizal roots. “That is,” LePage explains, “their roots possess a symbiotic fungal association [that] is critical when getting nutrients out of the soil.” But, as he realized, these two species actually have different types of mycorrhizae.
    The fungal strands of redwoods are associated with root tissues, and are specially equipped to extract nutrients from the soil in warm, rainy environments. But when the climate is dry or cold, these endomycorrhizal fungi can’t do their job. Pines, on the other hand, have mycorrhizae near the root’s surface. When the climate becomes cold or dry, as happened on Axel Heiberg, “the pines come into their own, because their ectomycorrhizae excel at obtaining nitrogen.” The redwoods couldn’t break their bond with their fungi, so the pines started to take over until, eventually, they dominated the northern forests. They had effectively pushed the redwoods into confinement.
    Axel Heiberg Island’s unique geology and the incredible deposit of preserved flora provided important insight into how a species can go into decline. Says Lisa Boucher, a paleobotanist at the University of Nebraska, “It’s an elegant multidisciplinary synthesis. This work has shown how key ‘choices’ in symbiotic relationships can strongly influence a group’s evolutionary and ecological success.” — D.W.
 

Hot moons
    Two planetary moons are generating considerable scientific speculation — and lots of heat. According to recent observations, Neptune’s moon, Triton, is experiencing significant global warming, while Io, one of Jupiter’s moons, now records the highest surface temperatures of any planetary body in the solar system.

Triton heats up
    Researchers from the Lowell Observatory, the Massachusetts Institute of Technology (MIT), and Williams College report in the June 25 issue of Nature that Triton, Neptune’s largest moon, has heated up noticeably over the past 10 years. Recent observations from the Hubble Space Telescope show that Triton’s atmosphere has doubled since the Voyager space probe visited the moon in 1989. The increase in Triton’s atmospheric pressure — strongly correlated to its surface temperature — implies a potential increase from about 37 Kelvin (about -392ºF) to 39 Kelvin — the equivalent of a jump of 22 degrees Fahrenheit on Earth.
    “Since 1989, at least, Triton has been undergoing a period of global warming. Percentage-wise, it’s a very large increase,” says James L. Elliot, an astronomer at MIT. “For a northern summer on Earth, it would be like the sun being directly overhead at noon, north of Lake Superior.” The most likely theory is that Triton is approaching an extreme southern summer, a season that occurs every few hundred years, Elliot explains.
    During this season, more direct sunlight hits Triton’s southern hemisphere, heating the polar ice caps. As a result, the nitrogen ice vaporizes. That gas joins the atmosphere, forcing the increase in pressure. Elliot and his colleagues were able to measure the pressure using one of Hubble’s Fine Guidance Sensors. When Triton passed in front of “Tr180,” a star in the constellation Sagittarius, the sensor measured the star’s gradual decrease in brightness. The starlight became fainter as it traveled through Triton’s thicker atmosphere.
    Other explanations for Triton’s warmer weather are also possible, the researchers say. Because the frost pattern on Triton’s surface may have changed over the years, the moon may be absorbing more of the sun’s warmth. Or, changes in the reflectivity of Triton’s ice may have caused the moon to absorb more heat. Whatever the reasons, the temperature change is significant; similar changes on Earth could drastically affect its climate. Elliot and the other astronomers hope to gain insight into Earth’s complicated environment by studying the changes on Triton. Although Triton is a very different planet (at -390ºF, it’s a bit colder), this factor actually helps the scientists. “With Triton, we can more easily study environmental changes because of its simple, thin atmosphere,” Elliot says. The atmosphere is gradually thickening, which could affect science as much as it affects Triton. But, as Elliot says, “When you’re so cold, global warming is a welcome trend.”

Io sizzles
    Neptune isn’t the only planet with a “hot moon.” Volcanoes on Jupiter’s satellite, Io, are erupting at temperatures between 2,000 and 3,000ºF, higher than any surface temperatures ever recorded on a planetary body. Planetary geologists at eight institutions, including Brown University, the University of Arizona (UA), Lowell Observatory, and the Jet Propulsion Laboratory, report in the July 3 issue of Science that high-temperature hot spots are more common on Io than previously estimated.
    Using Earth-based equipment and the Galileo spacecraft, the researchers identified at least 30 locations at temperatures greater than 700 Kelvin (800ºF). At least 12 different vents on Io spew lava at temperatures greater than 2,200ºF, and one vent may be as hot as 3,100ºF (2000 Kelvin). That’s three times hotter than the hottest sunlit surface of Mercury and a drastic change in temperature from the rest of Io’s surface, which, except for the hot spots, averages a chilly -243ºF.
    “The very hot lavas erupting on Io are hotter than anything that has erupted on Earth for billions of years,” says Alfred McEwen, director of UA’s Planetary Image Research Lab and lead author of the Science paper. “They are the highest surface temperatures in the solar system other than the sun itself.” The high temperatures are more than double the highest temperatures recorded by the Voyager spacecraft in 1979 and also exceed more recent measurements made by telescopes.
    McEwen and his colleagues calculated the temperatures using two instruments on Galileo that read the infrared signatures of the vents. From the 1979 measurements, scientists had inferred that Io’s volcanism was dominated by sulfur-rich lavas, but the new infrared wavelength observations indicated that the lavas are ultramafic silicates, specifically magnesium-rich pyroxenes. The lavas probably have a high melting temperature, the scientists explain, and could be produced by large degrees of partial melting. If this is the case, the mantle has undergone little differentiation, retaining its primitive composition. This “suggests that Io’s interior is similar to that of early Earth,” the authors write in Science.
    Another explanation is that “volcanic activity has strongly differentiated Io,” separating the mantle into layers of differing density and composition. Extreme differentiation is expected, given Io’s intense volcanism, says McEwen. “The evidence suggests we’re seeing heavy magma erupt to the surface,” he adds. But it’s harder for dense material to rise through a low-density crust. McEwen says that there could be some process that mixes the crust back into Io’s interior, but the scientists still aren’t sure how to explain what’s happening.
    They do know that Io is heated because of its elliptical orbit. Io passes close to Jupiter and then swings farther away; molded by Jupiter’s massive gravitational forces at the different distances, Io actually changes shape. This could cause Io to heat up. Co-author James Head, professor of geological sciences at Brown University, explains, “It’s almost as if Io is being kneaded by the tidal interactions between Jupiter and the other moons.” — D.W.
 

More efforts to boost funding
    As the 105th Congress draws to a close, many in the
scientific community wish the session would last a little longer. This Congress has raised the visibility of science in a number of bills, but none have passed and only a handful of days remain. The most recent bill, S. 2217, the Federal Research Investment Act, passed the Senate Commerce Committee in July. Even if it does not make it into law in this Congress, it may serve as a template in the next.

Previous efforts
    Efforts to increase funding for research and development (R&D) began back in January 1997 with the introduction of S. 124, the National Research Investment Act of 1997, by Senator Phil Gramm (R-Texas). Stating that “the United States simply does not spend enough on basic research,” Gramm introduced a bill to authorize a doubling of nondefense R&D over 10 years. The bill provides specific increases for the National Institutes of Health (NIH) and broadly calls for a doubling in funding for several agencies, including the National Science Foundation, National Aeronautics and Space Administration, National Oceanic and Atmospheric Administration, Department of Energy (nondefense research), Department of Education, and Environmental Protection Agency. As with all authorizing legislation, Gramm’s bill would not guarantee an increase in funding; the actual appropriations occur through a number of separate appropriations bills each year. But the bill would put Congress on record as supporting increases in R&D. The bill gained four sponsors and was referred to the Senate Committee on Labor and Human Resources because of its provisions on NIH.
    In October 1997, Sen. Joe Lieberman (D-Conn.), Sen. Jeff Bingaman (D-N.M.), and Sen. Pete Domenici (R-N.M.) joined Gramm to unveil a new, but similar bill: S. 1305, the National Research Investment Act of 1998. The bill differs principally from S. 124 in its start date (fiscal year 1999 instead of FY 1998) and bipartisan support rather than only Republican co-sponsors. The bill was also referred to the Labor Committee, where it, too, was ignored.

Federal Research Investment Act
    Building upon these earlier efforts, Senate Science, Technology, and Space Subcommittee Chair Bill Frist (R-Tenn.), Ranking Member John Rockefeller (D-W.Va.), and
S. 1305 co-sponsors worked to craft legislation that would fall under the jurisdiction of Frist’s subcommittee. Along with Sen. Conrad Burns (R-Mont.) and Sen. John Breaux (D-La.), the group unveiled S. 2217, the Federal Research Investment Act, on June 25, 1998. The latest bill differs from the earlier ones in several ways. It doubles R&D funding over 12 years, rather than 10. It also adds the Interior and Transportation departments to the list of agencies whose research will be doubled. The omission of the Department of the Interior, home of the U.S. Geological Survey, in earlier bills had drawn concern from geoscientists, who advocated for its inclusion in the later bill.
    Perhaps the most significant distinction between S. 2217 and previous bills is that it includes accountability provisions. The bill recommends that the White House Office of Science and Technology Policy should commission the National Academy of Sciences (NAS) to develop methods to evaluate federally funded R&D. The bill also instructs the administration to provide — in conjunction with the budget request — a detailed summary of the amount of R&D in the budget and a strategy for achieving the doubling by 2010. These provisions are aimed at strength-ening the evaluation of research and development. They follow the intent of the Govern-ment Performance and Results Act, which instructs agencies to develop goals and methods to achieve their goals, and to assess the success of their programs. The NAS study is intended to improve the account-ability of agencies conducting R&D because R&D outcomes are often difficult to predict and do not follow standard performance measures. The bill calls for the termination of programs that are determined to be below the acceptable level of success for two fiscal years in a row, with certain exceptions.
    Framers of S. 2217 slightly altered the wording so that the bill could slip past the Labor and Human Resources Committee, where similar bills had seen no action. Because it does not specify figures for NIH, the bill was sent instead to the Commerce Committee, where Frist’s subcommittee could act on it. The bill passed the subcommittee and later passed the full Commerce Committee by a unanimous vote. The bill may pass the full Senate in the final days of this Congress, but faces stiff competition for attention as legislators wrap up the session and head home to blaze the campaign trails for a fresh start in January.
—Kasey Shewey, AGI Government Affairs Program
 

Hot spots and low velocities
    The origin of hot spots is still up for debate, but work published in the July 24 Science suggests that hot spots originate in a 5- to 40-kilometer thick region at the base of the mantle. This region, known as the ultra low velocity zone (ULVZ), stands out for the unusual behavior demonstrated by compressional and shear waves passing through it. The velocities of P waves in this region are depressed by as much as 10 percent from the overlying mantle. Some scientists in the small group of researchers studying the ULVZ say this velocity reduction could indicate the presence of partial melt. These researchers have also theorized that hot-spot volcanism, such as in Hawaii and Iceland, could result from upwelling thermal plumes originating from the core-mantle boundary, where ULVZs have been observed. Recent seismological studies suggest that the core-mantle boundary is a structurally complex thermal boundary layer that could play a large role in core and mantle dynamics. “The discovery of patches of very low velocity, probably partially molten material, at the base of the mantle is probably one of the most exciting discoveries in the deep-Earth sciences in the past 10 years,” says seismologist Thorne Lay, chair of the Earth Sciences Department at the University of California-Santa Cruz.
    Mineral physicist Quentin Williams and seismologist Justin Revenaugh of UC-Santa Cruz and seismologist Ed Garnero of the University of California-Berkeley determined that, sta-tistically, the correlation be-tween the locations of known ultra low velocity zones and the locations of known hot spots has a 1-percent chance of occurring randomly. “It basically gives us a smoking gun for hot-spot genesis in the lower mantle,” Williams says. “Correlation is not causation, but in our view it’s the next best thing.” Williams says the work provides support for a long-standing idea that hot spots originate in the lowermost mantle.
    Williams and Garnero had also published work in the Sept. 13, 1996, issue of Science stating that the velocity reductions observed in the ULVZ most likely result from the presence of partial melt. That idea gained more ground this year with work published in the Feb. 12 Nature by John Vidale of the University of Southern California and Michael Hedlin of the University of California-San Diego. They observed the scattering of seismic waves in a 60-kilometer-thick layer near the core-mantle boundary beneath Tonga in the South Pacific Ocean. The scattering they observed suggests the presence of partial melt and small-scale convection at the core-mantle boundary, they write. (May Geotimes, p.10)
    Williams and colleagues analyzed the known distribution of hot spots and existing seismic studies showing ULVZs in six distinct regions (beneath the northern and central Atlantic Ocean, beneath Africa, south of Australia, and beneath the southwestern and northern Pacific Ocean). Their first analysis was an algorithm determining the probability that a given number of hot spots lying above the ULVZs could arise through random processes. The second analysis calculated the probability that random rotations of hot-spot distribution produced improved correlations with the structure of the lowermost mantle relative to the actual hot-spot distribution. “The reason we think the statistics are valid is we did the correlation in a number of ways to eliminate biases in hot-spot distribution or ultra low velocity zone sampling,” Williams says. “The correlation remains robust even when we did everything we could to eliminate biases in the datasets.” The team also conducted the analyses using tomographic models for the same 44 percent of the planet mapped for the ultra low velocity zones. “The ULVZs produced a better correlation with both hot-spot distribution and flux than either of the best correlated contours of the tomographic models,” the researchers write. Williams adds that the correlations between hot spots and mantle velocity anomalies decrease farther up the mantle. "You really have to go to the deep part of the mantle for a correlation."
    One obstacle the researchers faced was that only a few ULVZs have been observed. Williams says previous work spanned about 33 percent of the core-mantle boundary for presence or absence of the low velocity zones (much of that work has been conducted in just the past three years by a relatively small number of researchers, including Garnero and Revenaugh). The team conducted extra seismic studies to bring that percentage to 44, focusing on the region below Asia.
    The incomplete mapping of ULVZs still bothers Lay, who published an article with Williams and Garnero in the April 2 Nature that reviewed current knowledge of the core-mantle boundary. "Recent work has shown that the very strong waveform anomalies that indicate the presence of the ULVZ may be generated by quite localized structures," Lay says, The heterogeneity of wave velocities could represent localized pockets rather than a uniform layer, he and his colleagues wrote. "Thus, the correlation [by WIlliams and colleagues] may be an artifact of the gross extrapolation of area with ULVZ attributed to it. Further work and mapping of the structure will be needed to assess this." Further mapping of the zone, he adds, could negate the correlations made by the team.
    At the same time, Lay agrees with Williams and other ULVZ enthusiasts that an understanding of the ultra low velocity zone can lead to an understanding of the dynamics of the mantle and its heat transport. Williams feels confident that further research will support the idea that hot spots and ULVZs are directly connected. As a mineral physicist, he says, he wants to find out why partial melt in the zone would upwell to the surface only at hot spots. He also wants to know if the melted zones are stable over geologic time or are continuously regenerated, But like other researchers, he mainly wants to understand what is causing the observed ultra low velocity zone in seismic studies. "It's a very difficult problem at this stage and it's a really important problem for understanding Earth's dynamics. If we don't understand the ultra low velocity zone, we may not understand mantle convection. — K.B.

News Briefs

Energy in brief
Consumption: Energy consumption in April 1998 in the United States totaled 7.198x10¹⁵ British thermal units (Btu). According to the Energy Department’s Energy Information Administration, petroleum accounted for 2.991x10¹⁵ Btu (41.55 percent); natural gas, 1.822x10¹⁵ Btu (25.31 percent); coal, 1.559x10¹⁵ Btu (21.66 percent); hydroelectric power, 0.313x10¹⁵ Btu (4.35 percent); and nuclear power, 0.505x10¹⁵ Btu (7.02 percent).

Production: Domestic field production of petroleum
in April 1998 was estimated at 8,656 thousand barrels a day (crude oil — 6,484; natural gas plant liquids — 1,859), according to the Energy Information Administration. Domestic natural gas (dry) production in April 1998 was estimated at 1,566 billion cubic feet; domestic coal production in April 1998 was estimated at 91,935 thousand short tons.

Oil and petroleum imports: U.S. imports of crude oil and petroleum products in June 1998 averaged an estimated 10,725 thousand barrels a day, a decrease of 0.1 percent from June 1997. The American Petroleum Institute, Washington, D.C., reports imports met 52.76 percent of U.S. supply. In June 1997, imports averaged 10,736 thousand barrels a day, and met 53.60 percent of U.S. supply. Supply in June 1998 was 1.5 percent higher than in June 1997.
 

Earth Science Week is here
    This month marks the first annual Earth Science Week, a celebration of the geosciences and their contributions to society. Initiated by the American Geological Institute (AGI), Earth Science Week takes place October 11-17. Seventeen state governors have proclaimed Earth Science Week, and Oregon Sen. Ron Wyden entered the Earth Science Week Proclamation (written by the Association of American State Geologists) into the Congressional Record on July 15. AGI Program Manager Julie Jackson says AGI has mailed more than 7,500 Earth Science Week information packets in response to a wave of requests.
    Throughout the country, schools, universities, state geological surveys, museums, and geoscience societies are hosting special events during the second week of October to highlight the work of earth scientists and the contributions they make to our understanding of Earth. The philosophy behind Earth Science Week is that the earth sciences are fundamental to society and to our quality of life, Jackson says. The earth sciences are crucial for addressing environmental and ecological issues, and provide the basis for preparing for and mitigating natural hazards.
    A few activities planned for the week include:

•  In Washington, D.C., AGI will start Earth Science Week at Taste of D.C., an annual outdoor event that attracts more than 1 million people.
• Also in Washington, the IRIS Consortium (Incorporated Research Institutions for Seismology) hosts a celebration on Oct. 14 to honor seismologist Adam Dziewonski and geophysicist Don Anderson. The scientists won the Crafoord Prize from the Royal Swedish Academy of Science earlier this year.

What’s in the moon’s atmosphere?
    An intensive effort is underway to determine the composition of the moon’s tenuous atmosphere. Although conventional wisdom says the moon is devoid of atmosphere, and in layman’s terms this may be close enough to the truth, the space just above the lunar surface is not a total vacuum. Using the Suprathermal Ion Spectrometer (STICS) aboard the WIND spacecraft, a team of scientists headed by Urs A. Mall and Erhard Kirsch of the Max Planck Institute for Aeronomy in Germany have identified the elements of several ions, including small amounts of oxygen, silicon, and aluminum, in the lunar atmosphere. They will publish their findings in an upcoming issue of Geophysical Research Letters.
    Scientists believe the moon’s regolith, or surface layer, is a significant source of atmospheric sodium. They want to learn what other atoms the regolith releases and if those atoms form part of the moon’s atmosphere.
    The Apollo space program had identified helium and argon atoms in the atmosphere, while Earth-based observations made in 1988 found sodium and potassium ions. Researchers hope to find more ions when WIND spends an extended period of time near the moon in November. The WIND spacecraft was launched in 1994 as the first mission of the Global Geospace Science initiative, part of the International Solar-Terrestrial Physics (ISTP) program. The program aims to understand the physics of the Sun-Earth relationship. The spacecraft passes the moon periodically.