(0.02 to 0.08 inch inside diameter). Wound fiber is sealed with a pot­ting compound at the ends. It is sliced radially on one end to form a "tube sheet" conformation of from 100 to 200 open-ended spiral tubes, each 2 to 4 feet long.

Murch says the pore diameter of the materials is controllable between 0.06 and 1 /um. Pore volume of a unit varies from 25 to 50%. The spe­cific surface area of a typical unit is 250 sq ft. For water, liquid flux rate varies from 10 to 20 gal per sq ft per day per psi. Gas flow through the material has been measured at 0.2 standard cu ft per minute per sq ft per psi for nitrogen.

The units are resistant to thermal and mechanical shock. They can be operated at temperatures up to 1300 °C, depending on the potting ma­terial used, and they can be repeat­edly autoclaved. They have been successfully tested for long-term serviceability at 1200 psig.

Jack B. Wielar, manager of liquid separations in Du Pont's separation systems division, says the PRD-86 is still considered more of a filtra­tion device rather than a membrane per se. The uses he foresees are most­ly in the microfiltration area, in­cluding biotechnology, and in the filtration of liquid streams contain­ing hazardous materials or precious metals. Further extensions of this technology under consideration are organic and inorganic coatings to reduce pore size for ultrafiltration and/or gas separation, and coatings

Du Pont's PRD-86 ceramic filter, wound to form cylindrical unit

to modify surface reactivity to pro­vide simultaneous catalysis and sep­aration. A further use would be in the production of affinity mem­branes for bioseparations.

Du Pont has recently acquired Carre Inc., Seneca, S.C., which spe­cialized in the manufacture of powder-metal membranes, primari­ly stainless steel. None of these has yet been commercialized by Du Pont, according to Wielar. However, the present development program envisions major applications in the pulp and paper industry and in the processing of foods. Other applica­tions include chemicals manufac­ture, nuclear processing (enriched uranium recovery and low-level ra­dioactive waste concentration), the

What was Apollo about? Was the project to land men on the moon a dead end, as some critics charge, leading the U.S. space program no­where? Was it a pr ime case of misplaced national priorities, just a tremendously costly salvo in Cold War competition with the Soviets? Or is it having a lasting and benefi­cial impact on the U.S. and the world?

Such issues were debated recent­ly as the U.S. celebrated the 20th anniversary of the first manned moon landing—on July 20, 1969, by the Apollo 11 mission. Two sympo­sia on July 19 in Washington, D.C., for example, probed the historical significance of the lunar landing, and the past, present, and future of space exploration. One, held in the framework of the 28th International Geological Congress (IGC), brought together U.S. and Soviet experts. The other was sponsored by the Space Policy Institute at George Washing­ton University.

"Was Apollo a success?" asks John M. Logsdon, director of the GWU institute. The project's multiple goals mean there is no simple answer.

President Kennedy's pledge in 1961 to land men on the moon by the end of the decade was primari­ly a "politically motivated, symbol­ic" move to demonstrate U.S. tech­nological and organizational vitali­ty, part of the global struggle for

space program (water recycle), syn­thetic fuels (coal gasification), waste­water treatment, oil shale water pretreatment, and textile manufac­ture (dye recovery and closed-cycle operation). Wielar also notes that there is an immediate interest in the dewatering of municipal sludge and the treatment of hazardous wastes.

Carre had developed a composite membrane made from the porous tube in which special solutions are circulated to form in-situ membranes that adhere to the stainless steel. These form single-pass systems that can tolerate severe environments. Membranes so formed can be re­placed by recirculating the appro­priate solutions through the system.

Joseph Haggin

influence, Logsdon notes. Apollo was "one of the final acts of the Cold War." It was a response to the first orbital manned flight by Yuri Gagarin in April 1961. And this had been preceded in 1957 by what Wal­ter A. McDougall, a Pulitzer Prize-winning historian at the University of Pennsylvania, calls "a technolog­ical Pearl Harbor"—Soviet launch­ing of the first Sputnik satellite, which showed Soviet capacity to de­liver nuclear bombs to U.S. shores.

Politically, Logsdon notes, Apol­lo was a strong success. The Na­tional Aeronautics & Space Admin­istration, industry, and academia were mobilized. The high-profile project stimulated study of science and engineering. Successive achieve­ments on the way to the moon en­hanced national pride and interna­tional respect.

However, McDougall points out, Apollo took on a deeper meaning. "The U.S. government was steeped in the idea that government could apply a technological fix to remedy any problem." This "hubris" envi­sioned technology ending heart dis­ease, cancer, poverty, ignorance, and numerous other problems. This gave birth not just to Apollo, he adds, but to the Vietnam war, race riots, disillusionment with basic U.S. val­ues, and other crises.

Moreover, Logsdon and McDoug­all say, Apollo harmed subsequent

Impact of Apollo 11 moon landing probed

July 31, 1989 C&EN 35

Dow Corning Presents

he Abridged CPI Guide to Silicones Silicone sealants. Silicone lubricants. Is that all there is? For your plant and process, there's a whole lot more in silicones developed by Dow Corning. And our wide-ranging technol­ogy is continuously adding to the list of applications. Read on and find out how our silicones can help your process plant in ways you never imagined.

A maker of snack foods had a problem. Washing raw potatoes created a thick, gel-like starchy foam that attracted dirt, reduced production rates, and required constant clean-up. Organic antifoams failed —they clogged pipes. Dow Corning food grade antifoam zapped the foam. And made possible recovery of the starch for sale to a paper mill, which covers the cost of the antifoam.

CIRCLE 5 ON READER SERVICE CARD

Gunning down fire and fumes. Dow Corning® Fire Stop Sealant is a ready-to-use silicone elastomer you "gun" like caulk into simple electrical and plumbing penetrations. It goes in smoothly and tools easily. It's low-slump, so there's usually no need for damming.

For effective permanent seals of com­plex penetrations, such as multiple cables or cable tray pass-throughs, choose Dow Corning Fire Stop Foam. Its a two-part elastomer suited for automatic mixing and dispensing. CIRCLE 6 ON READER SERVICE CARD

Higher temperatures and a better environment. A pilot plant gets both with

Syltherm® 800 silicone heat transfer fluid.

!&* Unlike organic fluids which

^ ^ > can give off fr noxious vapors,

> Syltherm800 is odorless and presents no environmental hazard. Its working temperature is 750°F, so the plant can han­dle new kinds of experiments. CIRCLE 7 ON READER SERVICE CARD

Patch work for tankers. Case in point: Chemical tankers that suffer hairline cracks from expan­sion and contraction. To weld the cracks would take the tankers out of service. Epoxy patches are too brittle. But Dow Corning 730 RTV sealant was the tem­porary solution. It's a flexible seal that resists chemicals. The tankers can stay in service until there is time for proper repair. CIRCLE 8 ON READER SERVICE CARD

The 500,000 mile radiator hose. "I can't remember any instance where we broke or lost a radiator hose;' says a maintenance supervisor at a large transport company. The hoses are Dow Corning silicone rubber. After half-a-million miles of service, they look—and work—as good as new.

CIRCLE 9 ON READER SERVICE CARD

A world of silicones worldwide. Dow Coming's world of solutions with its products is unsurpassed among silicone suppliers —as is our global reach. Thirteen of our 24 manufacturing facilities are outside the United States. More than half our sales are over­seas, proving our ability to deliver technical support, people,

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DOW CORNING"

Dow Corning and Syltherm are registered trademarks of Dow Corning Corporation. © 1988 Dow Corning Corporation

Silicones, that's how. Dow Corning, that's who.

36 July 31. 1989 C&EN

No starch, please. No cost either.

Science/Technology

development of the U.S. space pro­gram. The dash to reach the moon by 1969 did not allow time or re­sources to develop across-the-board space capabilities. At the peak of its acclaim and capabilities, Apollo be­came "a dead-end project." After six Apollo flights to the moon, the last two missions—slated to be the most scientifically productive—were canceled by the Nixon Administra­tion to save money. The Apollo team was scattered, and the technology-spacecraft, lunar module, and Sat­urn 5 booster—"quickly became mu­seum pieces, rather than the foun­dation on which future U.S. space achievements would be bu i l t , " Logsdon notes.

In the 1970s, McDougall observes, "manned space flight survived only by clinging to the thin reed of an underfunded space shuttle project— which turned into the political and technological disaster of the 1980s, even before Challenge/' exploded. "NASA entered a two-decade iden­tity crisis from which it still has not completely emerged," Logsdon adds. It has "spent the past 20 years hop­ing for another Apollo-like goal around which to mobilize, rather than adjusting to the reality of low­er priority" in national affairs. And NASA "became a stagnant bureau­cracy with a fortress mentality, un­willing to share information or to admit problems."

Scientific research and long-term exploration of space were minor mo­tives in launching the Apollo pro­gram. However, participants in the IGC symposium emphasize, Apollo greatly advanced knowledge of the moon and facilitated subsequent un­manned probes of planets.

Another key impact of Apollo was cited at GWU by Frank White, an author and consultant, and at IGC by astronaut Kathryn Sullivan, a ge­ologist. For the first time, humans saw the indelible vision on a piece of film of Earth as a whole, as a fragile sphere suspended in space, arousing what White calls "the over­view effect." This sense of Planet Earth's finiteness and interconnect-edness is stimulating movements to nurture and protect it and its envi­ronment, White notes. "We're trying to create a global civilization, grop­ing to find a way of marshalling

the resources of the entire human community" to deal with global problems, and to create "a whole new value system."

"We now have the scientific tools and computer capability to organize the data, to see whole global sys­tems and how they interrelate and interact," Sullivan adds. NASA has very ambitious plans for such a "Mission to Planet Earth."

Thus, ironically, White notes, "Apollo was born out of competi­tion, but showed the limits of com­petition." Indeed, at IGC, promi­nent Soviet space scientist Valery Barsukov, director of the Vernadsky Institute of Geochemistry & Ana­lytical Chemistry in Moscow, urged U.S. and Soviet space scientists to "go from competition to real coop­eration. We should make our mis­sions complementary and plan joint missions," to speed research and cut costs. "I believe our scientific inter­ests and goals coincide."

Hardest to evaluate, Logsdon adds, is Apollo's significance in the vast history of human exploration and expansion. "How does one put a value, after only two decades, on the initial steps toward homo sapi­ens' becoming a multiplanet spe­cies? Like other initial ventures into unknown territory, Apollo may not have followed the best route, nor have been motivated by the same concerns that will drive those who follow," he says. "But without some-

Logsdon: hard to evaluate initial steps

one having been first, there can be no followers. The Apollo astronauts were true pioneers in the outward movement of humanity."

McDougall compares Apollo 11 to Ferdinand Magellan's first cross­ing of the Pacific Ocean in the ear­ly 16th century. Both journeys pio­neered a new empire and pushed known technology to its absolute limits, at great expense. And nei­ther was followed up for decades. "In 1539, we'd have considered Magellan's voyage a dead end, like Apollo seems now," he says. But in the long run, Apollo is "not a dead end—but awaits the development of new technology"—perhaps, for example, a new, cheaper propulsion method, "instead of sitting on top of Roman candles."

Richard Seltzer

Big new lab built at University of Michigan When visitors arrive in a couple of weeks for the dedication symposium at the University of Michigan's new Willard H. Dow Laboratory, they will find what Michigan chemistry de­partment chairman M. David Curtis believes is the largest chemistry building constructed by any Amer­ican academic institution, at least in the past decade. The building, with a total floor space of about 270,000 sq ft, cost $46 million to build.

Palm trees decorate the atrium, a functional feature that allows day­light to reach the building's below-ground level, which is devoted to laboratories for first- and second-year courses. Each of 14 labs is equipped with hoods for about 25 students. The ground floor has a 500-seat lecture auditorium, a 120-seat classroom, and five smaller classrooms. The second and third floors are devoted to synthetic chem­istry, with each floor having 23 four-person labs, each equipped with four or five hoods, and between every two an instrument room. The fourth floor has 36 600-sq-ft "open" labs that can be outfitted for special-purpose use.

Each floor contains special-pur­pose rooms, such as a cold chroma­tography room for biological sam-

July31, 1989 C&EN 37