Omni goes into Earth orbit on a mission to test a promising new space material

THE LIGHT STUFF

The spaceship Columbia zoomed silently through space. Deep in its cargo bay,
among rows of identical aluminum containers, sat Payload GAS. With a flick of a
switch, battery power turned the inside red hot--at 500 degrees Celsius, hot
enough to melt the unlikely mix of metals it contained and to produce a foaming
gas. The resulting metal foam then expanded into an I-shaped nozzel, like
meringue forced through a pastry bag. As it cooled, it formed a foamed metal I
beam.

Now only a small step in a shuttle mission dedicated to space medicine, the
zero-gravity metal-foam experiment may eventually represent a giant leap for
rivetheads in space. Someday construction workers may use this technology and
the alloys it produces to fashion high-strength, lightweight structures, such as
the controversial space station, in zero g or to form shields to protect massive
solar-powered satellites.

While the experiment took only 24 hours during Columbia 's nine-day journey last
June, the moment of truth fot Duke University engineering professor Franklin H.
Cocks was nine years in the making. His own journey began with Omni's Get Away
Special Contest of 1982. The NASA Get Away Special program makes use of leftover
space in the shuttl's cargo bay for civilian experiments. Omni offered to pick
up the $3,000 Get Away tab as well as all the construction expenses.

A few hundred readers responded, proposing experiments testing everything from
the embryonic growth of sea urchins to psychic spoon bending in space. Omni's
judges, including physicist Robert W. Bussard, inventor of the interstellar
ramjet, narrowed their choices to one: Cocks's novel scheme to create ultralight
metal compounds of magnesium, aluminum, and lithium in zero gravity. The judges
deemed his concept the likeliest to advance the cause of space development.

If such structures as an elaborate space station are ever to get off the ground,
they will have special requirements: Primarily they must be strong but weigh
little, since all building materials must be shipped from Earth.

Alloys of those ultralight metallic elements, Cocks theorized, just might fit
the bill. Such metals are rarely used on Earth because they react with the
atmosphere, corroding when exposed to oxygen and humidity.

In previous research Cocks, a 1963 MIT graduate and professor of materials
science at Duke University's School of Engineering, had noticed a fortuitous
relationship between metal density and reactivity: It appears to be a natural
law that the density of materials goes down as their chemical reactivity
increases.

"What this means is if you want to have extreme lightness in metals, then those
metals will turn out to be chemically reactive," Cocks says.

For example, metals like platinum and lead are dense but not reactive. Iron is
less dense and more reactive. Lithium is lighter still and extremely reactive.
(Reactivity is not an issue in space, which is free from the earth's corroding
atmosphere.)

If light metals could satisfy the weight requirement of space construction, what
about the prescription for strength? Cocks believed the answer lay in foam. Some
30 years ago Wernher von Braun suggested that lightweight, rigid structural
materials could be created in space by injecting bubbles into molten metal. "A
beam made of foamed metal is much stiffer than a solid beam of the same weight,"
Cocks says, "because the bubbles expand the material to a much greater
cross-sectional area, away from the natural bending axis."

Foaming the metal in a microgravity environment prevents the bubbles from
escaping from the heavier metal. Foaming should also save precious space on
shuttle missions. "For building small satellites, it's not worth the trouble,"
Cocks says. "But if you build something that has many thousands of tons of
material and you can lower the tonnage by a factor of two, saving maybe twenty
shuttle flights, then it becomes worth it."

The favorable strength-to-weight ratio could lend other space ventures a hand.
Cocks envisions using the foamed metals as a resilient satellite armor, the need
for which will grow along with the burgeoning volume of space debris. "'We're
talking about the chance of satellites being hit at velocities unachievable on
Earth-thirty-five thousand miles per hour," he says. "When you consider the
prospect of manned satellites, the need for shielding becomes obvious."

The ultralight metals also boast one intriguing environmental benefit. If a
satellite equipped with these reactive materials reentered the atmosphere, it
would burn up quickly rather than hazardously scatter its debris on Earth, as
Skylab did in 1979.

Developing such promising concepts was one thing. It was still a long way from
dreaming up an experiment to actually having one in the can. Cocks put to work a
group of eager young undergraduate engineering students who'd signed up for a
new course, space engineering. Unlike in the standard collegiate fare, the
class would actually see a tangible outcome: hardware that would fly in space.
The group's universe consisted of an aluminum canister, less than 20 inches
across and 15 inches high, that could withstand sound levels as high as 145
decibels and temperatures ranging from 110 degrees F to -296 degrees F. It
would weigh no more than 60 pounds, about the same as a fully loaded backpack.

The class faced a daunting set of testing criteria. Get Away rules mandated
that the experiment could not rely on the ship's power supply or personnel; the
astronauts aboard the shuttle would only activate the battery-operated
experiment and turn it off again with a single switch.

In the first year or so the student teams filled up as many as four labs in the
engineering school building. "We were under pressure a couple of times because
there were launch opportunities we could have taken but in fact we missed,"
Cocks says. "I felt if we rushed we'd fail the safety checks."

Extraordinary checks at that: NASA required that Cocks identify the source and
the use of every experiment component. A safety data package that covered all
safety aspects of the experiment had to be submitted in three phases, each phase
more detailed than the last one.

Finally a satisfactory design emerged. In quartz vials, a mixture of the various
light metals-magnesium, lithium, and aluminum-and titanium hydride would sit
inside a chamber capped with an "extrusion channel" in the shape of an I beam.
It would work like this: Beyond the inexorable pull of the planet, battery power
would melt the alloy and release hydrogen gas from the hydride. The gas would
bubble through the molten alloy, foaming it and forcing it through the channel,
thus molding a miniature I beam.

With the hardware now approved, the Omni-Duke payload was assigned to a flight
onboard the shuttle Discovery. Unfortunately, timing was everything: The flight
was to follow the illfated Challenger mission of January 1986, which killed all
of the seven astronauts aboard.

Get Away Special experimenters now faced new roadblocks. "After Challenger all
the rules changed," Cocks says. "No combustible materials of any type whatever
would be allowed on. We had to do the whole thing over again." Cocks's student
crew was forced to replace 147 pieces of a combustible heat shrink tubing with
Teflon tubing. They also threw out the hydrogen foaming agent, substituting a
magnesium substance. This in turn meant remixing the various metal alloys to
allow for temperature differences.

Other safety standards proved even more vexing. The foaming chambers of Cocks's
experiment hardware had to be vacuum sealed. Yet in order to pass inspection at
the time of launch, Cocks was forced to prepare twice the number of chambers
necessary for the payload, the idea being that three chambers, selected at
random by NASA safety engineers, would be opened to test the vacuum seals prior
to liftoff; if the seals held, the three remaining chambers would fly.

Then Cocks left the six chambers under an active vacuum pump system he'd
installed in a Duke basement lab. "That was the only way I could guarantee that
over a period of years the possibility of their slowly leaking would not lead to
the experiment being bumped off the flight," Cocks says. "The only way I knew
to do that was to maintain them under vacuum--which I did continuously for six
years."

In the spring of 1990 Omni finally got the thumbs-up from NASA to fly the
payload on a mission scheduled to lift off the following August. Cocks was
understandably nervous about those vacuum seals. Yet each of the three test
chambers passed the final safety check.

Further delays eventually pushed the launch back another nine months, to
May of 1991. Finally, with a sigh of relief, Cocks gave over the canister
and saw it lifted into the cargo bay of the shuttle Columbia.

The next time he saw it, several anxious weeks after the ship's return to
Earth, he was looking at three small I beams made of the reactive alloys and
yearning to get them back into the lab to test them for their resiliency and
strength. The miniature I beams were each composed of different metal
combinations: magnesium-aluminum, magnesium-lithium, and
aluminum-magnesium-zinc.

NASA has also offered to evaluate the material's ability to withstand
high-velocity impacts. Then Cocks will have some idea of how well his funny
foamed metal will fare against those particles whipping about in space.

The Duke University team joins an elite group-the small percentage of Get Away
Special experimenters whose projects actually work after they've met the
program's extraordinary requirements. "For the first time we have foamed light
reactive metals under zero gravity," says Cocks. "That has never been done
before."

He is the first to applaud the students whose efforts and enthusiasm over the
years kept the project alive. "One of the unsung benefits of the space program
is encouraging students to go into science and engineering," he says. "Our
experience certainly bears that out." Several of the course's students, he says,
have gone on to pursue careers in the space industry.

NASA has encouraged Cocks to retest his light stuff on a future shuttle mission,
possible if Cocks is able to secure another Get Away slot. Yet the professor
may first take a brief break from space to catch his breath. "NASA's system
does work," he admits, "but it works slowly."

Still, shuttle launches have a way of making up for a lot of grief. Early in
the morning on June 5 it was raining hard at Kennedy Space Center, and the
prospects for launching looked pretty grim.

In all, the engineering professor had made three trips to Kennedy during the
shuttle's final preparation. The first was that tense critical check of the
vacuums. The second time was a scheduled launch when engineers discovered a
flaw in the hardware responsible for guiding the spacecraft back into the
atmosphere and delayed liftoff for four days. That time they came within 40
minutes of launching. Cocks had had no choice but to pack up his car and his
wife and twin sixteen-year-old sons and drive the 12 hours back to North
Carolina, only to return three days later.

Now Cocks stood with his family and 200 or so other visitors on the viewing
stand peering anxiously out at the launch site and at the nearby monitors. NASA
will not launch in rain or through more than 4,500 feet of cloud cover, and
there was plenty of that.

"But there was this large patch of blue sky" Cocks recalls, "and it was drifting
our way. Then, my gosh, the blue patch drifted right over and they launched
through it."

A collective whoop went through the small crowd as the sound wave from
Columbia's mighty engines rolled over them. Fate, Cocks remembers thinking. "In
spite of all that technology, we still depended on that tiny patch of blue sky
drifting over us."