The Space Moss OdysseyOn November 19, 1997, plant biology researcher, Fred Sack; his post-doc Volker Kern and undergraduate student Nathan White watched their research go up in a blaze of glory. Sack's experiment with the moss Ceratodon, officially known as SPM-A, was launched into space in a history-making scientific mission involving plant biologists in the United States and the Ukraine.
Ohio State is one of three universities in the United States participating in a set of plant experiments collectively known as the Cooperative US and Ukraine Experiment, or CUE, which grew out of a 1994 White House initiative to promote cooperation between the Ukraine and the United States. This mission has successfully fostered a close working relationship between the Ukrainian and American researchers at all steps along the way.
At Ohio State, Professor Fred Sack's
group spent two years fine-tuning their experiment, which since
its inception has been fondly and unofficially known as both "Rolling
Stone," and "Spam" (for space moss). The twinkle
in his eye and the prominently-displayed poster, "Gravity:
It's Not Just a Good Idea. It's the Law," give a very good
idea of the humor and affection with which Sack pursues his work.
A famous architect once said, 'God is in the details.' That is
certainly true in science and particularly true in this case.
As Sack points out, "Spaceflight experiments are very expensive
and much less flexible than ground-based work. They take a huge
amount of preparation and tremendous effort on the part of a lot
of people. The experiment has to be very precisely defined very
early and worked out in excruciating detail."
But they have high hopes that over time, all the hard work and preparation will pay off with some definitive answers to the role gravity plays in plant growth and development. Specifically, they are looking for more information about the mechanical forces that act on the starch particles inside the cell; this will tell them something about how all cells prevent particles from simply distributing according to their mass (density). "In other words," Sack explains, "It is likely that the system of fibers in cells (the cytoskeleton) evolved in part to control the placement of particles with respect to gravity."
Sack designed the experiment, but postdoctoral researcher Volker Kern keeps the daily nuts and bolts work moving along, with help from Nathan White, an undergraduate plant biology major. The three form a well-oiled scientific machine, assisting and complementing each other's efforts.
During the 16-day space flight, Sack's experiment and those
of the other researchers aboard the shuttle were performed by
Ukrainian cosmonaut Leonid Kadenyuk, who came to the United States
early in January of 1997 to learn first-hand how to do the work
in space from the participating universities' researchers. 
The mission proved a learning experience for everyone, including NASA. Sack and Kern needed what proved to be a nonexistent piece of equipment both to house the moss safely and allow convenient access to perform the designated treatments in space. With the researchers' input, NASA designed and built a prototype for a new piece of hardware that looks like a simple box, but is a more sophisticated version of the old BRIC (Biological Research in a Canister) hardware. Called BRIC-LED, the block-shaped container has racks to hold a forest of moss in petri dishes and align them with illumination; allowing external control of both illumination and fixation. It turned out to be such a nifty piece of equipment that NASA plans to use it for future experiments.
Why send moss into space? Gravity affects the growth and development of both small and large plants, but imagine a field of corn or a tree being shot into space! Moss provides a neat, tidy package in which to carry out experiments that will help determine how much effect gravity has on plant growth. And Ceratodon is ideal for space flight experiment because one little petri dish contains hundreds of different cells, offering unique opportunities to address important questions in cell growth and development.
"But,
it's important to remember that while this is a fantastic opportunity,
it is just one type of experiment among many that you do to probe
basic biological questions," Sack says. The fact that Sack
has spent many long years doing the ground work, literally, gives
his spaceflight research a special context.
As a cell biologist, Sack is concerned with how cells evolved and the role of gravity in that evolution. Having spent most of his career studying gravitropism in plants, Sack says that how plants know which way is up is still a puzzle. "For that matter, how do our own cells know which way is up? Well—they don't." But, he explains, our vestibular apparatus senses the direction of gravity and feeds this information to cells in the body that "need" to know.
What is unique about this humble moss cell is that it both senses and responds to gravity. It is one of the few known cells in all of biology that both senses gravity and has its growth oriented by gravity. While everyone can see that plants grow toward light, and there is evidence that gravity plays a part in that orientation, it is harder to pin down precisely how strong that effect is, or how the forces of gravity and light interact. No one has yet figured out how to "turn off" gravity here on the ground the way we can turn off the lights.
Sack believes that gravity pulls tiny starch particles in the growing plant tip to the bottom, forcing the cell to grow in the opposite direction. Moss is ideal to test this idea since all its growth is initiated from a single cell. Sack sent two kinds of moss spinning around the earth, a normal variety wild-type that grows upwards even in the dark on earth, and a mutant variety that grows downward. How it would act without gravity could only be guessed at until now, although Sack surmised that without gravity to help plants find the light, those plants kept in the dark would grow in all directions. (Hold that thought.)
While Sack theorized, Kern had his mind on the logistics of the experiment. Together they knew they had to work out the little problems that could become major problems if not solved before lift off. To say they have it down to a science is more than a pun. Kern and Sack have a protocol for everything.
Because the hardware was brand-new, they had to do even more rigorous testing than usual. Simulating the whole 16-day flight each time, the researchers performed the experiment at Kennedy Space Center on four separate occasions, in September of 1996, and February, May, and August of 1997. This allowed them to find and fix anything that was not working properly. Among their many concerns were to keep everything totally sterile and to work out a precise timetable for the necessary steps in regulating the treatment procedures in space.
As one might imagine, this called for a well-rehearsed scenario to be firmly in place well before the launch date. Kadenyuk would be working on a very defined schedule in space. During the flight, the moss were to be put through 16 different treatments, with three petri dishes in each treatment. Treatments consisted of varying the duration and amounts of light the moss were given; some were grown only in darkness. Each of the 16 treatments ended with fixation at different times according to the schedule.
The experiments were "fixed" in space to preserve them in their state of pure micro gravity. Sack's was the first experiment on board to be initiated, starting just two hours after launch, when light was switched on for some of the plants, and was the last to be shut down before landing.
Kern's work on the moss experiment
began in July 1995, but he has been studying gravitational biology
since 1989. Two prior space experiments, part of his graduate
research in Germany, gave him valuable insight for this mission.
In February 1991, to prepare for his first space experiment, Kern went to Houston to test the hardware on the "vomit comet," the jet the astronauts train in and referred to in the movie, "Apollo 13." During this two-hour flight the pilot performs 30 parabolas, stomach-churning maneuvers that simulate both a 25 second period of micro gravity—or weightlessness, and 25 seconds of 2 G. The first flight left Kern shaken and vowing never to do it again, but at eight o'clock the next morning he found himself strapped in for ride number two, which now, as a seasoned pro, he found, "Wonderful. You feel that you can fly, finally."
Nathan White has been working in Sack's lab since January 1996. White transferred from Miami University because he wanted the opportunities a big research university can offer to undergraduates. He certainly came to the right place! During his first quarter he took a plant biology course from Sack, who at any given time has five or six undergraduates working in his lab and is always trying to recruit more. For the time being, White, who someday hopes to go to medical school, allowed himself to fall for gravity research in a big way!
A lot of White's work is tedious, measuring growth angles, for instance. But that doesn't bother him, "It's just part of doing science," he says. Also, part of doing science is trying to figure out better ways of doing things, something at which White has proved quite adept. In fact, Kern says, "Nathan invented the technique for measuring angles. It's amazing how many inputs came from him, techniques to make it better, and make things easier for me; I don't have time to do everything."
For his part in all of this, White is grateful, "Hats off to both Volker and Fred for the opportunities they have given me. The amount that Volker does let me contribute allows me to get involved intellectually much more than I ever expected."
Luckily all the hours White put in growing the moss, photographing it, and measuring growth angles became second-nature, because at Kennedy Space Center, his days were long, calling for both patience and stamina; planting samples, ensuring their sterility, double-checking for contamination. Twelve hours before the handover deadline, which is 17 hours before launch, they begin to plant moss and load it into the hardware. Sitting in a large sterile hood, White, Kern and the NASA payload engineers form a space-age assembly line.
To guard against the moss developing
any possible preorientation, since they want all the growth to
occur in space in micro gravity, they plant and load the moss
almost immediately. They know that moss won't grow too much during
the first 24 hours because it needs time to readapt after the
shock of planting. Even so, Kern says, "If we could, we would
plant an hour before launch and hand them to the astronaut when
he enters the shuttle!"
And even though they carefully time their work for hand over at a specific launch time, they are never sure that the launch will occur at the scheduled time. So even before the shuttle launches, they sit down and prepare the next batch of moss.
There is little time for rest. They know they must have these samples ready to go on the ground to serve as reference for those flying in the orbiter. These ground-control samples are grown in a big chamber that simulates the same temperature and humidity conditions as those in the shuttle and the researchers perform exactly the same things Kadenyuk is doing in space.
While the pre-launch work has been intense and sometimes seemed endless, the post-launch work will be just as time and energy-consuming. The work will be done in stages, first at the Plant Space Biology Research Lab at Kennedy Space Center where about three hours after landing, the scientists can finally get their hands on their samples.
Ukrainian scientist Dr. Christina Chaban will be joining them in the lab at Ohio State as they begin the next phase of work.
A gorgeous sunrise in Florida finds Sack, Kern, and White watching the sky anxiously. It is 7:30 a.m., December 14, and the shuttle is passing over Texas; within seconds they hear the sonic boom that announces its imminent approach; now they see it, floating effortlessly down; suddenly, it is there, huge, bigger than they remember. Now to get their hands on the moss!
The next two days pass in a highly-focused
frenzy of nonstop work, Sack and Kern taking pictures of all the
cultures, in both color and black and white, on all kinds of microscopes,
White processing the film. They didn't want to embed the samples
in plastic before they had the chance to capture them in their
pristine state. Before they could sleep, 70 rolls of film had
been shot and processed, and they had a new name for themselves:
Wombats (well-oiled machines).
Two days later, they had to do it all over again with the ground controls. "It was like doing six months of research in two days," Sack says.
Sack is relieved, "The hardware worked astoundingly well
and Leonid did excellent work in space." And while it is
far too early to talk about those definitive answers, there were
clear-cut, and unexpected, results. "We expected the orientation
in space to be random, but it was not. We found a clockwise rotation,
which is even apparent with the naked eye—big arcs, all clockwise."
Sack relates that this may be the first time that a system that uses gravity for orientation has turned out to have non-random growth in micro gravity. What Sack thinks this means is that there is some kind of internal cue that normally gravity would suppress.
"So we have two very clear results, non-random distribution of growth and the starch particles close to the cell tip, not randomly distributed."
This obviously opens up more questions and more room for exploration.
White has had a great undergraduate research experience. He has learned among many other things, that science is not for the impatient, the weak, or the fainthearted. And he has learned a myriad of skills that will stand him in good stead no matter what he decides to do in life.
While the maiden voyage of our moss travelers is over, the research is not. Because moss is such a great model system, it is sure to be orbiting the earth again. To paraphrase Sack, "It's not over till it's over," and you can be sure that whatever else might happen, the moss will keep rolling along.
Also, it should be noted that representing Ohio State at Kennedy Space Center were Dean Alan Goodridge and Ann Goodridge, Board of Trustees members Alex Shumate (chair) and son, Vice-Chair Ted Celeste and daughter and Tammy Longaberger and children.
We had hoped to have pictures of our heroes with Ohio's own space pioneer Senator John Glenn but those pictures apparently were lost somewhere between Florida and Ohio.