Last week the crew performed some setup and preliminary checkout activities of the Space Automated Bioproduct Laboratory (SABL) facility. SABL is a facility that can support a wide range of investigations across life sciences, physical sciences, and materials sciences, with a main focus on research that enables biological systems and processes. Developed by Bioserve, it will replace the existing two Commercial Generic Bioprocessing Apparatus (CGBA) that has been serving a major incubator function on ISS since 2001.
The SABL will have interchangeable inserts that will allow it to support a wide range of fundamental and applied research ranging from microorganisms through small organisms, cell and tissue culture, and small plants. An important feature on the SABL is the USB ports that support any modern scientific tool with USB connectivity to work with SABL, allowing for many future analytical tools to be used on the orbiting laboratory as science technology evolves.
SABL has a front door for the crew to easily access their experiments, and a set of cameras that allow the crew and scientists on the ground to watch experiments as they happen. This is a bonus for the crew, as they’ve often told us that they really enjoy the experiments where they can actually see what’s going on inside the box!
Lastly, a feature that’s important to the science logistics on the space station is the capability for the SABL to efficiently recharge NASA’s Cold Bricks, which is critical for carrying samples to/from ISS at 4 degrees Celsius. Many thanks to the CGBA for keeping so many life sciences and educational experiments running for 15 years! Now let’s get ready to settle into the latest technology that will welcome Earth’s scientific community to research in low-Earth orbit.
You may have heard the “caffeine buzz” around the Internet about the ISSpresso machine that recently launched to the International Space Station. It would be out of this world indeed to have a cup to go along with it. So we designed, fabricated, tested, and flight qualified one. In fact six such cups are now on the space station and ready for action. With real science backing the design, our microgravity coffee cup will do more than lift espresso to astronauts’ lips — it will also provide data on the passive movement of complex fluids as part of the Capillary Beverage investigation. The results will confirm and direct math models that help engineers exploit capillary fluid physics (capillary fluidics) to control how liquids move by designing containers specific to the task at hand. Whether getting the last drop of fuel for a rocket engine or delivering the perfect dose of medication to a patient, there are real Earth benefits behind the brew.
On Earth, gravity is responsible for making bubbles rise and liquids fall. Such mechanisms vanish in the weightless environment of orbiting spacecraft. In fact, in microgravity there is no concept notion of floating or sinking, or up or down. Other forces such as surface tension that are normally overwhelmed by gravity on Earth rise to dominate liquid behavior.
In a spacecraft, if the effects of surface tension are not understood, liquids (e.g., water, fuel) can be just about anywhere in the container that holds them. Similarly, the gas (e.g., oxygen, nitrogen) in such containers can freely range, too. You’re in for a challenge if you want to find where these fluids are and use them. Even if you just want to drink them. This is why in space you’ll only see astronauts drinking from bags with straws so that they can completely collapse the bag to assure the liquids come out. From a practical safety perspective, the bags also provide a level of containment.
When my laboratory heard of ESA astronaut Samantha Cristoforetti and the Italian Space Agency’s espresso machine investigation (ISSpresso) going to space, it got us thinking about that beautifully complex drink and how it would behave differently — especially whether the coffee would develop a crema or not. Currently, we don’t believe so because the bubbles that form during the espresso brew process won’t naturally rise to the surface due to absence of buoyancy in the microgravity environment. Other weaker forces often masked by gravity are present and will likely play an unearthly role in what happens, making the espresso fun to observe. It will be a different kind of fun altogether to get real science out of the process at the same time.
In a normal cup of espresso, carbon dioxide bubbles release and collect to form a crema. Some of the bubbles adhere to the walls of the cup, while the remainder rise and stratify due to their size in layers we refer to as foam. Steam rises above the surface of the crema in part condensing in an advancing front on the inside surfaces of the cup. The cup cools by natural convection and the aromatics waft at rates determined by buoyancy. These processes are completely induced by gravity!
When the influence of gravity is greatly reduced, as it is aboard orbiting spacecraft, not much of this stuff is going to happen. This will be unusual for the astronauts. Even the smell of the coffee diffusing through the crema is driven by natural convection currents in the air, which are absent in the microgravity environment. So the simple, every day fluid physics taking place in your daily coffee are highly dependent on gravity. From taste to smell, we anticipate what may even be a disappointing cup of coffee in space. But only the astronauts will know, and we will have to take their word for it in the hopes of one day trying this for ourselves.
You can imagine how many variables are at play for the drinking experience from a human factors perspective, but gravity influences many of these, too. Sinus drainage, saliva migration, time aloft, and others are reasonable microgravity-related parameters affecting one’s response to the drinking experience in space. We designed the Space Cup with the central objective of delivering the liquid passively to the lip of the cup. To do this we exploit surface tension, wetting conditions, and the special geometry of the cup itself. We have yet to learn the human-cup interaction in microgravity. The cup design forces the drinker’s nose directly over the fluid contents. But since the aromatics do not rise, one might expect a rather concentrated dose upon the first whiff. Maybe this won’t be a big deal since astronauts report a reduced sense of smell while in space, due to somewhat clogged sinuses. This is presumably due to the headward fluid redistribution that occurs in spaceflight.
We were highly motivated to make the cup transparent so we could observe all of the fluid physics going on in the process. It may sound nerdy, but that’s what we do—we study microgravity fluid physics in hopes of designing more reliable fluid systems for future spacecraft, and more effective fluid systems for applications on Earth.
Touching your lips to the rim of the cup establishes a capillary connection, almost like the wicking of water through a paper towel, allowing the drinker access to the entire contents. My colleagues and I have been doing research aboard station for more than 10 years. During the course of hundreds and hundreds of experiments, we’ve been developing the mathematical predictive tools and computational tools for such passive capillary fluidic processes. Now we are in a place to develop designs for systems in space — systems with promises of high reliability because they perform their function passively, without moving parts. Examples include things like urine treatment and processing, and systems to close the water cycle helping to enable truly long duration crewed space exploration. These same tools also help us with fuel systems, cooling systems, water processing equipment for plant and animal habitats, and much more.
Perfecting these systems can also help us prevent disasters in orbit or on long-duration missions such as the journey to Mars. For example, the primary oxygen supply systems on many spacecraft use electrolysis. If the system gets a single air bubble lodged within its tubing, it can shut down until the bubble is found and removed. To get a sense of working with these types of systems in space, you need an understanding of capillary phenomena from studies, believe it or not, like Capillary Beverage.
While fun, this study has plenty of design research behind it. Many of the aspects of our fluid physics research in microgravity are present in this simple cup demonstration — the effects of wetting, the effects of geometry, and the effects of fluid properties, especially surface tension. The results could provide information useful to engineers who design fuel tanks for commercial satellites, for instance. If you can find all your fuel, you can save costs and maximize the mission duration.
With this cup we can also study complex fluids that we have not previously addressed. For example, just adding sugar or milk to tea is expected to radically change the performance of the process of how the fluids move. We’ll approach this systematically aboard the space station. We’re starting off with water, then clear juice, then tea, tea with sugar, etc., including complex drinks like cocoa, a chocolate breakfast drink, and even a peach-mango smoothie. Undissolved solids, dissolved gasses, foams, free bubbles, surfactants, varying viscosities, temperature effects and more — all in little transparent 3D printed cups used by astronauts to drink on the space station. This progression from simple to complex beverages will give us a wealth of data — data which we aim to apply not just in space, but on Earth, too.
The astronaut(s) will set up the experiment near the galley, position the cup, camera, and lighting for orthogonal views (views at right angles), and a variety of experiments will be performed using the HD video as our quantitative data source. For example, when the astronaut fills the cup, the filing process is research. When the astronaut drains the cup, the draining is research. The static and dynamic interface shapes tell us everything we need to know, from wetting conditions to stability, to visco-capillary interaction. This is the exciting part for us! We see the profile of the interface, we watch particles and bubbles as flow tracers, we get velocities and volumetric drain rates, and all as functions of what the astronaut is doing — enjoying a cup of coffee! Astronaut Kjell Lindgren is planning to take up plenty of his own espresso during Expeditions 44/45. We have plenty to look forward to.
With this cup, most everything is taken care of passively by the shape of the cup. There isn’t a straight line in it. There are no moving parts. Wouldn’t it be nice if all the fluid systems on spacecraft worked like that? We know it would result in less worry on the ground. The simpler things are, the more robust their function and the less time is needed for maintenance.
Check out this video about our first version of a zero-g coffee cup.
What we are learning here is not just for space. All the design tools we are developing are applicable to small fluidic systems on Earth, too. For example, portable point-of-care medical diagnostic devices exploit capillary flow to passively move a very small sample of blood to any variety of regions on a testing chip. That makes it possible to diagnose infectious diseases in places where there is no power or where power is unreliable. It also reduces the time between sample collection and diagnosis and, therefore, initiation of treatment. We will report more on this connection in the future.
The next time you brew a cup of your favorite coffee, imagine what it might be like to take a sip from the Capillary Beverage cup aboard the International Space Station while watching the Earth go by. Then consider the fluids research off the Earth, that can make a difference right here on the Earth.
Mark Weislogel, Ph.D., is senior scientist and vice president of IRPI LLC and professor Mechanical Engineering at Portland State University. He was founded in microgravity fluid physics while employed at NASA’s Glenn Research Center. Whether in the private sector or academia, Weislogel has since continued to make extensive use of NASA ground-based low-gravity facilities and has completed investigations aboard space shuttles, the Russian Mir Space Station, and the International Space Station. He led the design of the Dryden Drop Tower, which has conducted over 4,000 drop tests and continue at a rate of over 1,000/year. Current efforts are directed to research, development, and delivery of advanced fluid systems for spacecraft.
In today’s A Lab Aloft, Dr. Larry DeLucas, a primary investigator for International Space Station studies on protein crystal growth in microgravity, explains the importance of such investigations and how they can lead to human health benefits.
We have many proteins in our body, but nobody knows just how many. Consider that the human genome project is more than 20,000 protein-coding genes, and many of these genes or portions of those genes combine with others to create new proteins. The human body could have anywhere from a half million to as many as two million proteins—we’re not sure. What we do know, is that these proteins control aspects of human health and understanding them is an important beginning step in developing and improving treatments for diseases and much more.
A protein crystal is a specific protein repeated over and over a hundred thousand times or more in a perfect lattice. Like a row of bricks on a wall, but in three dimensions. The more perfectly aligned that row of bricks or the protein in the crystal, the more we can learn of its nature. Today there are more than 50,000 proteins that have been crystallized and the structures of the three-dimensional proteins comprising these crystals have been determined. Unfortunately many important proteins that we would like to know the three-dimensional structures for have either resisted crystallization or have yielded crystals of such inferior quality that their structures cannot be determined.
Once we have a usable protein crystal—one that is large and perfect enough to examine—the primary technique we use to determine the protein molecular structures is x-ray crystallography. When we expose protein crystals to an x-ray beam, we get what’s called constructive interference. This is where the diffracted x-rays coming from the electrons around each atom and each protein come together, providing a more intense diffraction spot. We collect hundreds of thousands, sometimes millions of diffraction spots for a protein. The more perfectly ordered the individual protein molecules are within the crystals, the more intense these spots. The higher signal to noise ratio in these strong spots creates an improved resolution of the structure, allowing us to map the crystal in detail.
Using computers, we take those diffraction spots and mathematically determine the structure of where every atom is in the protein. For example, in most protein structures we can’t even see the hydrogen atoms. We guess where they are because we know the length of a hydrogen bond. So if we see a nitrogen atom from an amino acid that we know has a hydrogen linked to it, and then at a hydrogen-bonding distance away we see an oxygen atom, then we can make an educated guess that the hydrogen is pointed towards that oxygen atom, so we position it there.
While we can grow high-resolution crystals both in space and on the ground, those grown in space are often more perfectly formed. That’s the main advantage and reason we’ve gone to space for these studies. In many cases where we could not see hydrogen crystals on the ground, we then flew that protein crystal in space and let them grow in microgravity. Because of the resulting improved order of the molecules laying down in the crystal lattice, we were able to actually see the hydrogen atoms. Usually to see the hydrogen atoms, you are talking about getting down to a resolution of one angstrom, which is not easy to do—it would take 10 million angstroms to equal one millimeter!
We also can look at bacteria and virus protein structures to identify how to target those proteins with drugs. Having this information is very important to pharmaceutical companies and universities. That structure provides a road map that is critical for the understanding of the life cycle of the bacteria or virus.
We’ve only done a fraction of the more important complex protein structures–I’m referring to membrane proteins and protein-protein complexes. Protein complexes are often composed of two, three or more proteins that interact together to form new macromolecular complexes that are often important in terms of disease and drug development. Membrane proteins are the targets for about 55 percent of the drugs on the market today. Scientists have determined the three-dimensional structures for less than 300 membrane protein structures thus far. However, there remain thousands more for which the structures would help scientists understand their important roles in chronic and infectious diseases.
When we see a specific region in a protein and we know exactly where every atom is, chemists can design drugs that will interact in those regions. We can take some of the drugs they design that work, but maybe not as well as we would like. We then grow new crystals of the protein with the drug attached to the protein to see exactly how it’s bound to the protein. That lets other scientists—modelers—determine very clearly how the drug interacts with the protein, information that enables them to design new, more effective compounds. This whole process is called structure-based drug design.
The International Space Station provides a unique environment where we can improve the quality of protein crystals. During the days of protein crystallization studies on the space shuttle, one of the most frustrating aspects of the microgravity experiments was the length of time it took to produce a usable crystal. This is actually part of why space-developed crystals are better—they grow much more slowly. On the shuttle you only had 10-12 days for a study, but aboard the space station you have as long as you need.
As an astronaut and scientist, I personally flew a record 14-day flight in 1992 where we studied 31 proteins. I was looking at results and planning to set up new experiments, changing the chemical conditions to optimize the crystallization. The rule for my sample selection was that the proteins had to nucleate—that means to begin to grow a crystal—and grow to full size in three days. Once I got up there, however, by the third day nothing had nucleated. I was worried, but then on the fourth day I could see little sparkles where crystals had started to grow in about half of the proteins. By mission end I was really only able to optimize the crystal growth for six of the proteins. How much longer it takes a crystal to nucleate and grow to full size was a dramatic discovery.
With constant access to a microgravity lab, such as the space station, I am confident that we can improve the quality of any crystal. With protein crystals it is important to note that just because we get a better structure with higher resolution, it doesn’t at all mean it’s going to lead to a drug.
The ability to grow good crystals typically involves a great deal of preparation on the ground where we first express and purify and grow the initial crystals. But if space can give you higher resolution, there’s no drug discovery program that’s going to take a lower resolution option. From the time you determine that structure and chemists work with it, the typical time frame to develop a drug is 15 to 20 years and the cost is around a billion dollars. Identifying the structure of the protein crystal is only the first step. Many times even with the structure a project goes nowhere because the drugs they develop end up being unusable. There are so many aspects to drug discovery beyond the opening act of structure mapping.
If crystals and the structure of a target protein are available, pharmaceutical and biotech companies certainly prefer to use that structure to help guide the drug discovery. After the first 18 months they’ve developed the drug candidates, they may not need to use the crystal structure again for say 10 years. During that time they are doing clinical trials and pharmacology. The majority of the money it takes to get a drug approved by the FDA is after the initial phase. If you break down what they say is about a billion dollars to develop a drug, the portion needed to get the structure up front will range from half to two million dollars—a small fraction of the whole process.
For the upcoming Comprehensive Evaluation of Microgravity Protein Crystallization investigation we focused on two things. First, we selected proteins that are of high value based on their biology. Having this information of their structure can lead to new information about structural biology—how proteins work in our body. The other major requirement for the candidates for selection was that the proteins had to have already been crystallized on Earth, but the Earth-grown crystals were not of good quality.
We are flying 100 proteins to the space station on SpaceX-3, currently scheduled for March 2014. Twenty-two of these are membrane proteins, 12 are protein complexes, and the rest are aqueous proteins important for the biology we will learn from their structures. The associated disease was the last thing we considered, as we were looking at the bigger picture of the biology. That being said, for the upcoming proteins flying you can almost name a disease: cystic fibrosis, diabetes; several types of cancer, including colon and prostate; many antibacterial proteins; antifungals; etc. There are even some involved with understanding how cells produce energy, which I suspect could lead to a better understanding of molecular energy.
Not long ago a Nobel Prize was awarded for the mapping of the ribosomes complex protein structure. This key cellular structure will also fly for study aboard the space station, because the resolution was not all that great using the ground-grown crystals. We now have the chance to learn more about how the ribosomes actually makes proteins and clarify the whole process. This is just one of the exciting projects flying in relation to protein crystal growth.
This space station experimentation is a double blind study. This means that all the experiment chambers are bar coded for anonymity. We also will have exact controls done with the exact same batch of proteins prepared at the same time. The crystals will grow for the same length of time, as they are activated simultaneously in space and on the ground. When the samples come down, we will perform the entire analysis not knowing which are samples grown in space versus Earth. Only one engineer will have the key to the bar codes. When we’re completely done with the analysis, then he will let us know which were from space or ground. This will allow our study to provide definitive data on the value of space crystallization.
We also wanted to ensure that our analysis looked at a sufficient number of samples, statistically speaking, to provide conclusive data. How many data sets we collect per crystal sample will depend on the quality of that crystal. Statistically the study will be relevant in terms of how many proteins we fly, as well as how many crystals we evaluate from space and ground to make the comparison.
The microgravity environment is so beneficial because it allows the crystals to grow freely. Without the gravitational force obscuring the crystal molecules, as seen on Earth, the crystals can reveal their full form. We are giving all of these protein crystals the chance to grow to their full size in a quiescent environment. This is a very important investigation, not only because of the high number of proteins we are flying, but the statistical way we will evaluate them. Based on the results of the study, we will know if PCG in space is worth continuing.
Once the crystals come back to Earth, it will take at least one year to complete the full analysis. However, we will likely know that we’ve got some exciting results within the first three months. To publish something, it will be at least a year to complete the analysis, as we will have about 1,400 data sets to analyze. These results will determine the future of microgravity protein crystallization.
Larry DeLucas, O.D., Ph.D. is Director for the Center of Structural Biology and a professor at the University of Alabama at Birmingham. Dr. DeLucas flew as a payload specialist on the United States Microgravity Laboratory-1 flight, Mission STS-50, in June1992. His work is currently funded through NASA and the National Institutes of Health.
In today’s A Lab Aloft, International Space Station Chief Scientist Julie Robinson, Ph.D. speaks with NASA experts in microgravity research disciplines. Together they take the opportunity of the 15 year anniversary of the station to reflect on accomplishments and discuss what’s next aboard the orbiting laboratory.
It’s hard to believe that the International Space Station has already celebrated 15 years in orbit with the anniversary of the first module, Zarya. That decade and a half included nail-biting spacewalks, and an assembly of parts designed and built around the world that was a miraculous engineering and international achievement. Our research ramped up after assembly was completed in 2011, and we are nowhere near done. In fact, with NASA Administrator Charlie Bolden’s recent announcement that the space station will continue operations till 2024, this is a time of opportunity. With full utilization already at hand, an ever-growing research community is enthusiastic about what’s next in discoveries and benefits for humanity.
I want to share with you the thoughts from some of my colleagues who have worked to enable these key achievements leading up to this milestone year for the various space station disciplines. I also asked them to share what they look forward to as we continue. With space station planned for the next decade and likely beyond, this is no time to rest, but to ramp up and make full use of this amazing laboratory.
The most important development on the space station is the emergence of a public-private partnership enabled by congress in designating the station as a National Laboratory. Managed by the Center for the Advancement of Science in Space (CASIS), this National Laboratory provides funding avenues for universal access for users, in addition to NASA-funded research. “Through the creation of CASIS, our organization is able to leverage partnerships with commercial companies, other government agencies and academic institutions to generate a variety of research capable of benefitting life on Earth,” said Gregory H. Johnson, President and Chief Executive Officer of CASIS. “The foundation of NASA-funded research discoveries on the space station helps us work with new users interested in applied research. Each year this user base is expanding due to the past success and the future promise of life sciences, materials science and Earth remote sensing.”
From a technology perspective, the design and assembly of the space station is a major international collaborative achievement in and of itself. Beyond this, the station is a unique technology test bed for everything from remote Earth sensing instruments to life support for distant destinations, such as an asteroid or Mars. As NASA’s International Space Station Technology Demonstration Manager George Nelson noted, “In these first 15 years of the space station we have managed to launch, activate, and use the state-of-the-art spaceflight systems that enable long-duration human missions. We continue to evaluate their performance and, using what we learn, we are taking steps to mature those systems in ways that better allow us to explore our solar system.”
When it comes to remote Earth sensing, the space station is not only a test bed, but an orbital platform capable of providing a constant watch on our planet, as well as our universe. William Stefanov, Ph.D., senior remote sensing specialist with NASA’s International Space Station Program Science Office, provides an overview of the station’s orbital perspective on our planet.
“During the past 15 years, the space station has become recognized as a valid and useful platform for Earth remote sensing,” said Stefanov. “Handheld camera imagery collected by astronauts from the earliest days of the station have demonstrated its usefulness as both a compliment to more traditional free-flyer sensor systems and as a vantage point in its own right, providing unique opportunities to collect both day and night imagery of the Earth system due to its inclined equatorial orbit.”
“The space station is now viewed by NASA and its international partners as an attractive platform to test and deploy advanced multispectral and hyperspectral passive sensor systems for land, oceanic/coastal, and atmospheric remote sensing,” said Stefanov. “We also can support humanitarian efforts related to disaster response through collection of remotely sensed information for disaster-stricken areas. The capacity to host active sensor systems, such as lidar, is also being explored. The space station is well on its way to expand its role as a test bed and become an integral part of the NASA fleet of Earth remote sensing satellites.”
While the various sensors aboard station take quite a bit of physics into account, it’s important to note that there’s plenty of physics going on inside, too. The space station also is a laboratory for fundamental physics microgravity research. I spoke with International Space Station Fundamental Physics Senior Program Executive Mark Lee, Ph.D., about station contributions in this discipline.
“In the past 15 years I think we have done a couple of really important investigations on the space shuttle before the space station came into use,” said Lee. “Specifically the Lambda Point Experiment (LPE) and the Confined Helium Experiment (CHEX) investigations. These two look at the quantum effect in a very low temperature also coupled with the dimensionality in a bulk three dimension, versus a confined limit to a two dimensional space, to see how the quantum physics behaved. These studies were provided by Mother Natureof which we cannot change, but from now on we can design our own quantum systems.”
According to Lee, quantum physics is mysterious and still barley understood, making future investigations fertile grounds for progress. “Though humanity has known of quantum physics for just a about 100 years, before the 1990s, however, we had to rely on nature to provide us with a quantum system. For instance, superconductivity, superfluid in liquid helium, even a neutron star anda black hole are gigantic star quantum systems. In the next decade on the space station we are developing the Cold Atom Laboratory (CAL)as a ‘designer’s quantum system’ apparatus.”
A multi-user facility, CAL’s design will enable the study of ultra-cold quantum gases in microgravity from aboard the space station. The primary goal is to explore extremely low temperatures, previously inaccessible, for quantum phenomena.
Lee continued, “The ability to study Bose Einstein condensates (BEC) and extremely cold atoms in space is a totally new dimension. With the kind of manipulation we will have in CAL, we can create different atom interactions and novel quantumconfigurations in such a way by manipulating individual atoms to look deeply into the quantum effect. Even Einstein’s Equivalence Principle (EEP) can be tested in space for the first time using this quantum system vs. that of previous classical ones.This is a very exciting area. This excitement, of course, is reflected in the Nobel Prize awards for related areas of study in 1997, 2001 and 2005. I can’t wait to see what happens when researchers can superbly cool and control a quantum system on the space station.”
Another exciting area of study in microgravity is that of physical science. Natural elements such as fluids and fire react quite differently and are some particularly interesting and useful areas of study in this environment. Program Executive for Physical Sciences, International Space Station Research Project Fran Chiaramonte, Ph.D., also weighed in on where we’ve been and where we are going.
When asked about the discipline of physical science in microgravity thus far, Chiaramonte responded, “I think the top achievement was the cool flames discovery. This was made when flames were detected at a temperature significantly below the known ignition temperature for the liquid droplet fuels we were studying in space. This came out of what we call the Flame Extinguishment Experiment (FLEX) where we were looking at droplet combustion in the Combustion Integrated Rack (CIR). The finding was unexpected from that research. Follow-on investigations will continue the quest to understand these flames and better define their characteristics. This has applications in the automotive industry—the findings would hand off via research publications and would be of value to them.”
Chiaramonte cited that in looking to the future, it is the early space station investigations that provide the basis for what’s next. Especially when talking about fluid physics. “In complex fluids, it started with a series of very simple experiments on phase separation between a host liquid and polymer particles. In a weightless environment, these particles will remain suspended in the solution almost indefinitely. On Earth they would settle to the bottom of the container and the experiment would be over before any meaningful science could be done. Over time the particles clumped together and separated out of the solution.”
“These precursor experiments led up to the next series of tests, called the Advanced Colloids Experiment (ACE) series,” continued Chiaramonte. “Now scientists study similar types of solutions under a microscope with a range of magnification and we are looking for a more strategic outcome. For instance, Paul Chaikin, Ph.D., is studying the self-assembly of particles, which has been a plaguing challenge for the future of advanced optical materials. In that work, they have successfully arranged one-dimensional line of particles, and have now successfully arranged a two-dimensional line of particles. This has important industrial applications.”
“It will take many researchers beyond Chaikin’s work,” said Chiaramonte, “but by using the space station for that kind of study, we can anticipate a major contribution in this area of three-dimensional ordering of particles and optical computing.”
From questions looking at the microscopic scale of physical phenomena, we now move on to the important minutia within our own bodies with the study of life sciences in microgravity. In speaking with Space Biosciences Division ChiefSid Sun, the research that stands out to him from the space station’s tenure involves the importance of where we’re heading next.
“In life sciences what we’ve been able to do over the last 15 years is answer at a first level the various questions that are associated with life in space,” said Sun. “Essentially how the unique environment of space, such as the microgravity and different radiation levels affect living organisms. As is typical with science, every time you answer one question, a whole other set of questions pop up, so that’s where the future of the research will take us. In particular, we’ll be studying more of the changes in the genomics of living systems.”
“Something that the advances in biotechnology are allowing us to do now is better understand what is happening in the basic genetic code within organisms and how that code is being expressed or not expressed in space compared to Earth,” Sun continued. “The space station allows studies of record length for a wide variety of organisms. On the space shuttle scientists were limited to from 10 to 14 days every five years. Now with the continued orbit of the space station we are able to do experiments in microgravity for months, maybe heading into half a year to a year in length, and we continuously have scientists study a wide variety of organisms. That is going to be especially critical as we look to study humans in space for multiyear missions.”
These findings flow to future areas of study, where model animals will play an important role. “Being able to study other organisms, especially rodents, will shed a lot of insights into how spaceflight will be affecting people for long periods of time. In particular, during space station assembly, pharma demonstrated that space biomedical research could enable both drug discovery on Earth and biomedical research important for astronauts. With the new Rodent Research Facility we’re developing for the space station we’re going to take that research to the next level, again taking that research into longer experiments and having more animals up there. It will be high speed compared to the experiments of the past.”
While model animal studies are key to human health developments, our crew also serves as test subjects for a variety of important investigations. From the beginning, our astronauts collected samples, kept journals and participated in experiments to help increase the understanding of what life in space meant for the human body.
“The first 15 years of the space station provided us with a much deeper understanding of how humans respond to six months of space flight and how to deal with those changes,” said Craig Kundrot, Deputy Chief Scientist, Human Research Program. “We have learned how to prevent or limit problems like bone loss, muscle loss, or aerobic fitness. We have discovered new changes that were not as clear in the one to two week long shuttle missions: changes in the immune system and visual impairment, for example. We have pushed technology to new limits, like the use of ultrasound for the detection of bone fractures and kidney stones.”
“In the ensuing years, we seek to overcome the remaining challenges like visual impairment,” Kundrot continued. “We also plan to progress from overcoming the challenges one at a time to overcoming the challenges with an integrated suite of countermeasures and technologies that keep the astronauts healthy and productive in future exploration missions.” These findings and the development of countermeasures and treatments are not limited to space explores, but have real world applications. From strengthening bones for those suffering from osteoporosis to boosting the immune systems of the elderly and immunosuppressed, there is much to gain from human research in microgravity.
With so much to be proud of in our 15 years of assembly and operations, it’s not surprising we have plenty to look forward to. From my perspective, I am particularly excited to see what space station researchers will discover next. Now is the time for microgravity studies to come into their own. While these future endeavors are fascinating, I am especially touched by the ways such findings return for expanded use on the ground. Whether addressing health concerns, advancing engineering designs, or inspiring the next generation, the space station may have already secured its place in history, but we are far from mission end. If anything, we have only just begun!
Julie A. Robinson, Ph.D.
International Space Station Chief Scientist
Julie A. Robinson, Ph.D., is NASA’s International Space Station Chief Scientist, representing all space station research and scientific disciplines. Robinson provides recommendations regarding research on the space station to NASA Headquarters. Her background is interdisciplinary in the physical and biological sciences. Robinson’s professional experience includes research activities in a variety of fields, such as virology, analytical chemistry, genetics, statistics, field biology, and remote sensing. She has authored more than 50 scientific publications and earned a Bachelor of Science in Chemistry and a Bachelor of Science in Biology from Utah State University, as well as a Doctor of Philosophy in Ecology, Evolution and Conservation Biology from the University of Nevada Reno.
In today’s A Lab Aloft, Mike Hicks, project scientist at NASA’s Glenn Research Center in Cleveland, blogs about discovering the “cool” world of combustion aboard the International Space Station.
In a recent posting on this blog one of our International Space Station combustion researchers, Sandra Olson, noted that when it comes to combustion experiments in microgravity one should expect surprises. This has certainly proven to be true with one of our liquid fuel combustion investigations currently operating aboard the space station.
The Flammability and Extinction (FLEX) study burns liquid fuels dispensed in the form of small, single droplets. The goal is to answer two key questions: the first is how difficult it is to keep a flame burning in microgravity? We call this flammability mapping. The second is how effective is gaseous carbon dioxide (CO2) (or other diluents) in extinguishing spacecraft fires? Gaseous CO2 is particularly important because this is the current fire suppressant used in the U.S. module of the space station.
To answer these and other “burning questions” the FLEX team of scientists studies small droplets of fuel. This approach allows a large number of tests to take place under a wide range of conditions. The flame that results from igniting these fuel droplets (ranging in size from 1.0 mm to 6.0 mm in diameter) achieves a shape that can only happen in a reduced gravity environment—that is, they become little glowing balls of fire.
Within fractions of a second following ignition, the reaction front—visualized as a flame—quickly wraps around the fuel droplet and assumes a spherical shape. This remains mostly motionless until the droplet of fuel is consumed or until the conditions are such that the flame can no longer exist. You can watch the Strange Flames on the International Space Station video to see these microgravity flames in action.
The overarching goal of FLEX is to better understand the complicated physical processes behind determining whether or not a flame can exist in a given environment for a given fuel type. The environment varies based on the amount of oxygen in the combustion chamber along with other gases that balance out the test atmosphere.
Since combustion processes are rich in physics and chemistry, there are many parameters that play a role in flame survival. The FLEX experiments allow scientists a way to study these competing physical processes—such as the rate of fuel consumption, fuel characteristics, the controlling energy and mass transfer processes, and the physical properties of the gases that make up the test environment. By understanding and modeling these processes, we hope to better predict fire behavior in space. This also leads to Earth technology advances, such as more fuel efficient engine designs.
FLEX recently led us to a “cool” discovery, igniting the imaginations of many combustion researchers. During one of their many late night test sessions, the FLEX operations team noticed a very peculiar orange afterglow about 20 seconds after the flame had extinguished. It was so intense that the team first thought something else other than the fuel droplet was burning.
After a few repeated tests, the team concluded that this bright afterglow resulted from tiny droplets of re-condensed fuel vapor. The idea was that these tiny droplets formed a fog, scattering the yellow-orange backlight that is used to project the droplet’s shadow onto one of the diagnostic cameras. The afterglow was initially dismissed as an artifact of the test configuration—or so we thought.
A few days later we recovered the data from the space station and processed the images for accurate measurements. As we looked closely at the droplet shadow images we realized this glow was actually a clue to something new.
Typically when a flame extinguishes, the evaporation of the fuel droplet will nearly stop, and the droplet stops shrinking, which makes entirely good sense—no flame, well then, no fuel consumption. We discovered with FLEX that under certain conditions when the flame disappeared, the droplet of fuel continued to evaporate at almost the same rate as when the flame was visible. In many cases this “apparent” fuel consumption without a flame lasted longer than with the flame.
Even more startling, we saw that when the pressure of the chamber was slightly increased, the flame momentarily reappeared in a brief flash before quickly going out again. In some cases this phenomena repeated until the fuel was consumed. This finding has a number of interesting ramifications, both from a purely scientific perspective as well as from a fire safety perspective. It provides the first direct observation of a long held concern—the possibility that microgravity conditions were conducive to re-ignition of flammable mixtures.
At first glance, it seemed irrational that the fuel droplet continued to evaporate with no visible flame. Some of the science team argued, myself included, that this could be explained by characteristics of the test chamber environment. It was suggested that once the visible flame extinguished, that there was still a sufficient amount of energy remaining in the surrounding gases to continue the rate of the droplet’s evaporation.
Since buoyant forces are absent in microgravity flames, the hot gases simply remain stationary around the droplet—so we theorized that as these gases cooled, heat transferred back into the droplet. We quickly realized, however, that this would have resulted in a gradual slowing of the droplet’s evaporation rate, which was not the case. During the “dark burning periods” when no flame was visible, the evaporation rates were essentially constant, similar to what is seen with a visible flame. Interestingly, these evaporation rates suddenly stopped when the afterglow of the scattered light began to appear.
In 65 years of previous droplet experiments, and employing a staggering breadth of microgravity test configurations—from converted mine shafts in Japan to experiments performed on the recently retired space shuttles—this phenomena had never been observed. The prior universal observation was that when the flame went out, the rapid evaporation of the droplet stopped. However, with these tests we now had a fuel droplet that continued to be consumed at a rapid rate without an apparent flame.
So what exactly is a cool flame and why is it important? The discovery of cool flames is often attributed to Sir Humphry Davy in 1812. While investigating flames for the purpose of designing safety lamps for coal miners, Davy observed that he could generate flames in the lab that were so weak that they could would not even ignite a match. This finding was followed by W.H. Perkins, who published in 1882 the first investigation of cool flames. Perkins observed that vapors of organic fuels produced what he characterized as “blue lambent flames.” Generally speaking, cool flames are the visible light of oxidation reactions occurring at low temperatures, sometimes nearly 10 times less than normal flame temperatures.
Cool flame temperatures depend on fuel type and atmosphere. For n-heptane—the alkane fuel used in the FLEX experiments—cool flames appear at temperatures just above 600 degrees Fahrenheit. This is about 176 degrees Fahrenheit warmer than the temperature for baking bread and considerably less, by about 1,300 degrees Fahrenheit, than the flame one might roast a marshmallow over. Hence the name “cool flame.”
Despite the name, these flames’ temperatures are still sufficiently high to sustain chemical reactions. Understanding exactly what kind of chemical reactions are taking place, as well as the conditions necessary to propel the chemistry into the high temperature realm of hot flames, are key research areas in the study of cool flames.
Prior to the FLEX discovery, it was thought cool flames were primarily pre-ignition phenomena generally limited to pre-mixed gases. If you’ve ever taken your car in for engine knocking, you’ve experienced an example of this. Pockets of gas in the cylinder undergo low temperature reactions (i.e., cool flames) that result in poorly timed pressure peaks. These deviations from the optimal peak pressure timing that should occur shortly after spark ignition result in the noise often associated with engine knock.
The FLEX study, however, showed a post-ignition cool flame. This occurred in a controlled system where reactants are initially separated, requiring time to travel to the reaction zone, which we see as the flame. This appears as a relatively steady phenomenon, suggesting a delicate balance between heat generated by the reaction and heat losses to the surrounding—to date, only achievable in space.
The microgravity cool flame discovery is significant for a number of reasons. Low temperature combustion in internal combustion engines, for instance, offers a number of advantages: reduced emissions, less wear on engine parts and increased fuel efficiencies. A better understanding of these low temperature burning regimes may help address challenges facing new internal combustion technologies, such as the Homogenous Charge Compression Ignition (HCCI) and Reactivity Charge Compression Ignition (RCCI) engines. Since these technologies lack a spark for localized ignition, knowledge of cool flames may help with precise timing of the combustion event—based, in this case, on a reactant mixture that may only be partially pre-mixed.
Microgravity cool flames are exciting in their own right, because of the potential for refining our understanding of a very complicated combustion phenomena. This is true of all serendipitous discoveries, giving one more example of how the space station provides an opportunity for discoveries that would otherwise never get made.
Mike Hicks, project scientist at NASA’s Glenn Research Center in Cleveland, has been with NASA for 22 years and is currently probing the mysteries of droplet combustion as a co-investigator on the Flammability and Extinction (FLEX) study. He is also the principal investigator on the Supercritical Water Mixture (SCWM) International Space Station flight investigation, which is designed to study precipitation phenomena in near-critical water. Hicks spends much of his free time as a doctoral candidate at Case Western Reserve University putting the finishing touches on a dissertation he plans to complete in the fall of 2013.
In today’s A Lab Aloft, guest blogger Fred Kohl, Ph.D., International Space Station Physical Sciences Research project manager at NASA’s Glenn Research Center in Cleveland, talks about some of the physical science investigations that take place in microgravity aboard the space station.
Extremes are part of exploration, whether you’re talking about space travel or probing new areas of discovery to expand knowledge in a given science. So it is appropriate that the extreme environment of the International Space Station provides an ideal location to study physical sciences, from flames to fluids.
Removing gravity from the equation aboard this Earth-orbiting laboratory reveals the fundamental aspects of physics hidden by force-dependent phenomena where a fluid phase (i.e., a liquid or gas) is present. Such experiments, which investigate the disciplines of fluid physics, complex fluids, materials science, combustion science, biophysics and fundamental physics, use the station’s specialized experiment hardware to conduct studies that could not be performed on the ground.
The main feature differentiating the space station laboratory from those on Earth is the microgravity acceleration environment that is stable for long periods of time. Conducted in the nearly weightless environment, experiments in these disciplines reveal how physical systems respond to the near absence of buoyancy-driven convection, sedimentation, or sagging. They also reveal how other forces, which are small compared to gravity, can dominate the system behavior in space. For example, capillary forces can enable the flow of fluids in relatively wide channels without the use of a pump.
These findings may improve the understanding of material properties, potentially revolutionizing development of new and improved products for use in everything from automotives to airplanes to spacecraft. With so much to learn in the area of physical science and so many investigations, I would like to highlight several studies ongoing, upcoming or recently looked at aboard the space station.
Studying mixed fluids in microgravity for CVB-2 provides data to further optimize the performance of wickless heat pipes. These pipes weigh less and have reduced complexity as compared to the more common construction with a wick. The CVB-2 study examines the overall stability, fluid flow characteristics, average heat transfer coefficient in the evaporator, and heat conductance of a constrained vapor bubble under microgravity conditions as a function of vapor volume and heat flow rate.
Findings from this research may lead to more efficient ways to cool electronics and equipment in space, while also applying to advances in Earth technologies such as air conditioning and refrigeration systems. Laptop computers also use this type of heat pipe technology to cool their electronics in order to prevent overheating.
ACE studies colloidal particles in space for use in modeling atomic systems and engineering new systems. These particles are big enough—in comparison to atoms—to be seen and recorded with a camera for evaluation. Conducting this study aboard the space station removes gravitational jamming and sedimentation so that it is possible to observe how order rises out of disorder, allowing researchers to learn to control this process. This could lead to greater stability and longer shelf life for products on Earth, such as paints, pharmaceuticals and other products based on colloids. Recently we launched additional hardware, consisting of a magnetic mixer and a drill kit, to use in mixing the samples for future ACE experiments.
The CFE investigation is a suite of fluid physics flight experiments designed to study large-length scale capillary flows and phenomena in low gravity. Testing will probe dynamic effects associated with a moving contact boundary condition, capillary-driven flows in interior corner networks, and critical wetting phenomena in complex geometries. The sample fluids flow in specific directions influenced by the shape of unique cylindrical containers called Interior Corner Flow (ICF) vessels.
For CFE-2 there are 11 units of fluids for astronauts to test. This research and the resulting math models based on the data findings helps with the design of more efficient fuel systems for spacecraft. This is because the engineers will be able to design the shape of the tank to take advantage of the way fluids move in microgravity. On Earth these findings may contribute to models to predict fluid flow for things like ground water transport, as well as the afore mentioned cooling technology advances for electronics.
The objective of this investigation is to observe and characterize evaporation and burning of renewable-type fuel droplets in high-pressure conditions. Test runs for this study recently took place in the Combustion Integrated Rack (CIR) aboard station. Research conducted in the CIR facility includes the study of combustion of liquid, gaseous and solid fuels. The CIR is made up of an optics bench, combustion chamber, fuel and oxidizer control, and five different cameras for performing combustion experiments in microgravity.
Researchers can use the results of these experiments to develop and validate thermo-chemical and chemical kinetics computer models of renewable liquid fuels for combustion simulation in engines. This helps with the design of the next generation of fuels and advanced engines. The computer models may reduce costs to industries and benefit the general public by accelerating the adoption of renewable fuels that are environmentally friendly.
The SCWM investigation will help researchers look at phase change, solute precipitation, and precipitate transport at near-critical and supercritical conditions of a dilute salt/water mixture. When water is taken into its supercritical phase—a temperature higher than 705 degrees Fahrenheit and a pressure higher than 3,200 psia—it becomes highly compressible and begins to behave much like a dense gas. In its supercritical phase water will experience some rather dramatic changes in its physical properties, such as the sudden precipitation of inorganic salts that are normally highly soluble in water at ambient conditions.
The primary science objectives of the SCWM investigation are to determine the shift in critical point of the liquid-gas phase transition in the presence of the salt, determine the onset and degree of salt precipitation in the supercritical phase as a function of temperature, and to identify the predominant transport processes of the precipitate in the presence of temperature and/or salinity gradients.
On Earth water reclamation from high-salinity aquifers, waste handling for cities and farms, power plants, and numerous commercial processes may benefit from the SCWM findings. A good understanding about the behavior of salt in near-critical and supercritical conditions also would assist designers of the next generation of reactors. With the knowledge gleaned from SCWM, they could possibly design systems that would operate without incurring large maintenance problems.
With the still relatively new frontier of microgravity research, there are many questions to pose and angles to consider. The scientists that pursue the answers using the laboratory we have available 200 miles above us are embarking on a journey of discovery that I dare say will yield some amazing findings. As Albert Einstein said, “To raise new questions, new possibilities, to regard old problems from a new angle, requires creative imagination and marks real advance in science.”
Fred Kohl is the International Space Station Physical Sciences Research project manager at Glenn. Since the mid-1980s, he’s been involved in the advocacy, definition, development and conduct of more than 250 experiments in ground-based facilities and aboard the space shuttles, Mir space station and the International Space Station in the disciplines of fluid physics, complex fluids, combustion science, fundamental physics, materials science and acceleration environment characterization. Before joining the microgravity program, he conducted research in high-temperature materials chemistry and high-temperature materials corrosion related to aircraft engine applications. He holds a B.S. in chemistry from Case Institute of Technology and a Ph.D. in chemistry from Case Western Reserve University.
Whatever missions we look to tomorrow—including travel to an asteroid and Mars—they absolutely depend on the success of the space station. That is because the station was developed to return benefits and discoveries to us here on Earth. How we use the space station, both in our success as an industry and in returning benefits back to our nations and our economies, impacts everybody. If we don’t all take ownership to share this story, it makes our stakeholders look at our future ideas and say, “well yeah, that’s great for you, but what’s in it for the rest of the country.”
I was originally challenged to pick a set of top 10 research results by the organizers of an aerospace industry meeting, the International Astronautical Congress. Now I would like to challenge not only the members of the aerospace community, but all of those reading this blog who may one day benefit from this orbiting laboratory—that means you. Please take home one of these top ten research facts to share with your family, friends and colleagues. There are many more benefits and results than just those I highlighted, but it’s a good place to start.
Of the examples I gave you in this series, be ready to own the one that you choose. If you are talking with a government official, the press, your students, your family, that stranger sitting next you to on a plane, whomever you encounter, be prepared to share. The space station is our pinnacle of human spaceflight, it is our example of international cooperation and it is doing outstanding things in science yesterday, today and tomorrow. You don’t have to be a scientist to share the wonder and the value of the science we are doing there with others.
To make the difficult choice of a top 10 possible, there are a lot of things I didn’t include in the list. Sometimes, these were more technology spinoffs than research results. I also didn’t include the specific knowledge being gained for the purposes of future exploration—that could be another top 10 by itself. The use of space station ultrasound techniques in saving lives of women and their unborn children around the world, for instance. New remote ultrasound practices are being tested in developing nations, but this was a pure spinoff—no additional research needed—which is why it did not make my list. I also did not touch on the space station technology used today for air purification in daycares or the fresh water technology from station. Again, I did not select these primarily because they are pure spinoffs.
These examples are equally impactful and perhaps even more quickly connected to saving lives here on Earth. I encourage you to learn more by visiting our resources as we continue to share new developments, findings and benefits from space station research. Why limit this topic to so few as just ten; quite frankly, why limit the conversation to just the aerospace industry?
Amazingly enough, people you know have not heard about the space station, so we all need to take responsibility for sharing this message. There are some great resources we’ve put together as a partnership for you, so you won’t have to just remember the words you read here. You can look at the space station benefits for humanity website, which has been translated into multiple languages. You also can keep up on all the great things going on by following space station research on nasa.gov, revisiting this A Lab Aloft blog and by following our Twitter account: @ISS_Research.
I’d like to close by pointing out how sharing a view of the space station over your town can have a big impact on the people in your own orbit. My husband does not work in aerospace; he’s in the insurance industry. I remember one time there was going to be a great overpass of the space station in Houston, and I suggested to him that he go up on top of his building to see it. He sent an email around his office as an invitation and he ended up on the roof of the building with his colleagues and a senior executive. Together they watched this amazing space station pass. While looking up, the executive leaned over to my husband and said, “that was really neat! I had no idea we had people in space.”
The fact is that leaders in the world of business outside of aerospace are not paying attention to what we are doing. Science policy position and analysis can have scant information about what is really going on and what we are accomplishing. In the din of public policy debates, it is sometimes hard for us to get people hear about the good news. Two things that we really need to share with everyone are that the space station is up there with humans working on orbit, and that it is bringing back concrete benefits for use here on Earth. These returns make our economies stronger, make our individual lives better and save peoples’ lives. That really is the core of space exploration and why we do it.
Here, again, are my top ten space station research results in review.
In today’s A Lab Aloft entry, International Space Station Program Scientist Julie Robinson, Ph.D., continues the countdown of her top ten research results from the space station, recently presented at the International Astronautical Conference in Beijing, China. Be sure to check back for daily postings of the entire listing.
Number six on my countdown of the top ten International Space Station research results is an exciting finding for a new process of cool flame combustion. Cool flame combustion is an interesting term, because to a scientist a hot flame is in the range of thousands of degrees, while a cool flame is in the range of hundreds of degrees—600 to 800 degrees Celsius.
Aboard the space station, we use a facility called the Combustion Integrated Rack (CIR) for experiments where we burn droplets of fuel. In the image below you can see what that looks like in microgravity during the Flame Extinguishing Experiment (FLEX and FLEX 2) investigations. FLEX principal investigator Vedha Nayagam, Ph.D., National Center for Space Exploration Research/Case Western Reserve University, was honored with an award in recognition of this cool flame discovery at this year’s International Space Station Research and Development Conference.
On the left you see a droplet of heptane fuel burning. You can see it burns in a sphere and doesn’t look like a candle flame at all, because there is no density or buoyancy-driven convection on the space station. This means warm air does not rise in the same way as it would on Earth, so instead you get this blue, spherical flame. What’s really interesting is what happens after the combustion quenches.
At a certain point in time, the combustion products start suffocating the oxidation reaction—the flame goes out. What was discovered with FLEX was that after a period of time, researchers saw an unexpected afterglow. In the right hand picture above you can see that event enhanced photographically.
That afterglow, it turns out, is combustion continuing at a much lower temperature (600 degrees Celsius or 1,112 degrees Fahrenheit—still hot enough to burn you!); a “cool flame.” This was previously an unknown process, so it is too soon to say what the application of this finding will be over time. This first discovery was published in Combustion and Flame, but a lot of analysis and modeling will need to be done to include this new process in our understanding of combustion without gravity. I think it’s obvious to see, however, that if you can learn about a new property of combustion that was not in the models before, there should definitely be applications to help in the design of more efficient combustion in processes on the ground. It just may take a while before we see them come to fruition.
The amount of combustion research done aboard the space station far exceeds all the combustion studies done in space over the last 50 years. Having a 24/7/365 laboratory makes all the difference in making discoveries.
Julie A. Robinson, Ph.D.
International Space Station Program Scientist