Four Caltech Physics Students Take the Ride of Their Lives

Kids often dream of being astronauts, rocketing into space and returning as heroes. Most kids outgrow this fantasy by the time they start junior high school. Not so for a team of physics students at California Institute of Technology.

The students--ages 20 to 22--got one step closer to their goal by boarding NASA’s infamous “vomit comet” at the Johnson Space Center in Houston over the Labor Day weekend. The KC-135 Stratotanker plane earned its ominous nickname by the way it flies--a pattern of steep arcs that allows passengers to experience micro-gravity, or weightlessness. It’s a ride that leaves many nauseated.

That experience may not be for everyone, but teams from across the country go to Houston to ride the plane and conduct experiments that require weightless conditions.

For the Caltech students, the micro-gravity ride was a chance to examine a new fiber-optic material called ZBLAN. NASA and telecommunications researchers hope ZBLAN may eventually be used to make fiber-optic lines that could transmit information far more efficiently than current cables. The students are interested in that, but in something else, too--their experiment with ZBLAN is a way of advancing the dream of a career in space.

For the four Caltech undergraduates--Dirk Englund, Serena Eley and John Ferguson, seniors majoring in physics, and Joseph Jewell, a sophomore majoring in aeronautics--the experience comes as part of NASA’s Reduced Gravity Student Flight Opportunities Program.

The NASA program provides a real-life research experience from start to finish. The students had to write a detailed research proposal, raise their own funds and conduct research. They will also speak to high school students about their experiences. A panel of NASA scientists selected student teams for the program based on the soundness of the science in their proposals and the extent of their outreach plans.

Writing Proposal Was Toughest Part

As many career scientists can attest, writing the proposal is the hardest part. The proposal was “really tough,” said Englund, “because we had finals going on at the same time, and classes for physics juniors are just hell anyway.”

“We had to do a lot of all-nighters to get it done,” added Eley.

Once the writing was done, the students had to raise thousands of dollars to pay for the special ZBLAN glass they would need for their experiment, as well as to cover their travel expenses and buy various supplies.

“We’re just a group of four undergrads,” Englund said. “We say, ‘We’re going to build this. We’re going to take it on the [NASA] plane, so give us $10,000, please.’ Then the challenge becomes convincing the donors that we’re worth their money.”

Convince them they did. Lute Maleki, senior research scientist at the Jet Propulsion Lab in Pasadena, agreed to advise the team and to supply the optical glass to the tune of $5,000.

“I told them they had to be very serious about this,” he said. The students’ proposal, he added, demonstrates that “they’ve shown a strong commitment; this isn’t just some flight of fancy.”

Tom Tombrello, chair of the division of physics, mathematics and astronomy at Caltech, put up an additional $5,000.

“When you have faith in somebody, you put up the money,” he said. He encourages students at the university to seek out creative and innovative projects and looks for ways to reward them when they do.

The purpose of the students’ work is to find a way to improve the way fiber-optic cables send information--in the form of pulses of light--over great distances. Light travels down the fiber of an optical cable much the way water travels through a hose.

But silica glass made from sand or quartz, which is now used in fiber optics, has limitations in its ability to transmit light. Glass made of ZBLAN, an acronym for the chemical symbols of the elements that make it up--zirconium, barium, lanthanum, aluminum and sodium--potentially could transmit light about 100 times farther than silica glass.

The problem comes in the manufacture of ZBLAN fiber. To make fiber-optic lines, glass must be heated and drawn out like saltwater taffy. When ZBLAN is heated and cooled under the influence of gravity, the glass crystallizes quickly, making it cloudy and useless for communications. But under micro-gravity conditions, ZBLAN remains perfectly clear during heating and cooling.

Weightlessness Aids Project

Exactly how gravity affects the glass during heating is unknown, but Englund explains one theory:

Picture a box full of marbles, he says. All of the marbles are about the same size, but some are heavier than others. When the box is shaken, the heaviest marbles accumulate at the bottom of the box. Without gravity, however, the marbles would mix evenly during the shaking.

The molecules in the ZBLAN glass are like the marbles in the box, this theory holds. When the glass is melted on the ground, the individual molecules become segregated during the melting, sorting themselves out by weight and creating little clusters of zirconium, little clusters of barium, and so on. Those clusters allow crystals to form when the glass cools, leading to tiny impurities in the glass.

Aboard NASA’s micro-gravity plane, the students fit ZBLAN fibers into a machine that heated them to make “microspheres”--a tiny glass lollipop that forms at the tip of a fiber when it becomes very hot.

A Step Toward Careers in Space

Back on the ground, the students plan to spend many hours in the lab analyzing the properties of the ZBLAN glass. The microspheres will give clues as to how the material will perform when turned into long cables.

Dennis Tucker of NASA’s Marshall Space Flight Center in Huntsville, Ala., has been studying the effects of gravity on ZBLAN glass for seven years. He is excited about the students’ project. “Anything we can do to get to the bottom of this [effect] is wonderful,” he said.

As for the students, they hope the experience will help get them closer to careers in outer space.

Jewell says he would be happy to work for NASA, even on the ground. But, he adds, “I’d be happier in space.”