Preparations for Next Moonwalk Simulations Underway (and Underwater)
How do we do research in zero gravity?
Actually when astronauts do experiments on the International Space Station, for instance, to environment on organisms, that environment is actually technically called microgravity. That is, things feel weightless, but we’re still under the influence of Earth’s gravity.
Now, the very microgravity that we’re trying to study up there can make experiments actually really kind of difficult for a bunch of different reasons.
First of all, stuff floats. So losing things in the ISS is a very real possibility. For example,
there was a set of tomatoes that was harvested in 2022 put it in a bag and it floated away and we couldn’t find it for eight months.
So to prevent this kind of thing from happening, we use a lot of different methods, such as using enclosed experiment spaces like glove boxes and glove bags. We use a lot of Velcro to stick stuff to.
Another issue is bubbles in liquids. So, on Earth, bubbles float up, in space they don’t float up, they’ll interfere with optical measurements or stop up your microfluidics. So space experiment equipment often includes contraptions for stopping or blocking or trapping bubbles.
A third issue is convection. So on Earth, gravity drives a process of gas mixing called convection and that helps circulate air. But without that in microgravity we worry about some of our experimental organisms and whether they’re going to get the fresh air that they need. So we might do things like adding a fan to their habitat, or if we can’t, we’ll take their habitat and put it somewhere where there might already be a fan on the ISS or in a corridor where we think they are going to be a lot of astronauts moving around and circulating the air.
Yet another issue is the fact that a lot of the laboratory instruments we use on Earth are not designed for microgravity. So to ensure that gravity doesn’t play a factor in how they work, we might do experiments on the ground where we turn them on their side or upside down, or rotate them on a rotisserie to make sure that they keep working.
So, as you can tell, for every experiment that we do on the International Space Station, there’s a whole team of scientists on the ground that has spent years developing the experiment design. And so I guess the answer to how we do research in microgravity is with a lot of practice and preparation.
When it comes to experiments in space, astronauts on the International Space Station face challenges you won’t find on Earth: bubbles don’t rise, things floa...
Unearthly Plumbing Required for Plant Watering in Space
NASA is demonstrating new microgravity fluids technologies to enable advanced “no-moving-parts” plant-watering methods aboard spacecraft.
NASA Astronauts Sunita Williams and Butch Wilmore during operations of Plant Water Management-6 (PWM-6) aboard the International Space Station.
Image: NASA
Crop production in microgravity will be important to provide whole food nutrition, dietary variety, and psychological benefits to astronauts exploring deep space. Unfortunately, even the simplest terrestrial plant watering methods face significant challenges when applied aboard spacecraft due to rogue bubbles, ingested gases, ejected droplets, and myriad unstable liquid jets, rivulets, and interface configurations that arise in microgravity environments.
In the weightlessness of space, bubbles do not rise, and droplets do not fall, resulting in a plethora of unearthly fluid flow challenges. To tackle such complex dynamics, NASA initiated a series of Plant Water Management (PWM) experiments to test capillary hydroponics aboard the International Space Station in 2021. The series of experiments continue to this day, opening the door not only to supporting our astronauts in space with the possibility of fresh vegetables, but also to address a host of challenges in space, such as liquid fuel management, Heating, Ventilation, and Air Conditioning (HVAC); and even urine collection.
The latest PWM hardware (PWM-5 and -6) involves three test units, each consisting of a variable-speed pump, tubing harness, assorted valves and syringes, and either one serial or two parallel hydroponic channels. This latest setup enables a wider range of parameters to be tested—e.g., gas and liquid flow rates, fill levels, inlet/outlet configurations, new bubble separation methods, serial and parallel flows, and new plant root types, numbers, and orders.
Most of the PWM equipment shipped to the space station consists of 3-D printed, flight-certified materials. The crew assembles the various system configurations on a workbench in the open cabin of the station and then executes the experiments, including routine communication with the PWM research team on the ground. All the quantitative data is collected via a single high-definition video camera.
The PWM hardware and procedures are designed to incrementally test the system’s capabilities for hydroponic and ebb and flow, and to repeatedly demonstrate priming, draining, serial/parallel channel operation, passive bubble management, limits of operation, stability during perturbations, start-up, shut-down, and myriad clean plant-insertion, saturation, stable flow, and plant-removal steps.
PWM-5 Hydroponic channel flow on the International Space Station with: (1) packed synthetic plant root model in passive bubble separating hydroponic channel, (2) passive aerator, (3) passive fluid reservoirs for water and nutrient solution balance, (4) passive bubble separator, (5) passive water trap, and (6) passive gas/bubble diverter. The flow is left to right across the channel and the aerated oxygenating bubbly flow is fully separated (no bubbles) by the bubble separator returning only liquid to the ‘root zone.’ The water trap, bubble diverter, root bundle and hydroponic channel dramatically increase the reliability of the plumbing by providing redundant passive bubble separating functions.
Image: J. Moghbeli/NASA
PWM-5 and -6 Root Models R1 – R4 from smallest to largest: perfectly wetting polymeric strands modelling Asian Mizuna.
Image: IRPI LLC
The recent results of the PWM-5 and -6 technology demonstrations aboard the space station have significantly advanced the technology used for passive plant watering in space. These quantitative demonstrations established hydroponic and ebb and flow watering processes as functions of serial and parallel channel fill levels, various types of engineered plant root models, and pump flow rates—including single-phase liquid flows and gas-liquid two-phase flows.
Critical PWM plumbing elements perform the role of passive gas-liquid separation (i.e., the elimination of bubbles from liquid and vice versa), which routinely occurs on Earth due to gravitational effects. The PWM-5 and -6 hardware in effect replaces the passive role of gravity with the passive roles of surface tension, wetting, and system geometry. In doing so, highly reliable “no-moving-parts” plumbing devices act to restore the illusive sense of up and down in space. For example,
hundreds of thousands of oxygenating bubbles generated by a passive aerator are 100% separated by the PWM bubble separator providing single-phase liquid flow to the hydroponic channel,
100% of the inadvertent liquid carry-over is captured in the passive water trap, and
all of the bubbles reaching the bubble diverter are directed to the upper inlet of the hydroponic channel where they are driven ever-upward by the channel geometry, confined by the first plant root, and coalesce leaving the liquid flow as a third, redundant, 100% passive phase-separating mechanism.
The demonstrated successes of PWM-5 and -6 offer a variety of ready plug-and-play solutions for effective plant watering in low- and variable-gravity environments, despite the challenging wetting properties of the water-based nutrient solutions used to water plants. Though a variety of root models are demonstrated by PWM-5 and -6, the remaining unknown is the role that real growing plants will play in such systems. Acquiring such knowledge may only be a matter of time.
100% Passive bubbly flow separations in microgravity demonstrated for PWM ‘devices’: a. bubble separator, b. bubble diverter, c. hydroponic channel and root model, and d. water trap. Liquid flows denoted by red arrows, air flows denoted by white arrows.
A Lysozyme crystal grown in microgravity, viewed under a microscope using X-ray crystallography.
NASA
Did you know that NASA conducts ground-breaking research in space on materials like metals, foams, and crystals? This research could lead to next-generation technology that both enables deep-space exploration and benefits humanity.
Here are six studies scientists have conducted on the International Space Station that could have profound implications for future space travel and also improve products widely used on Earth:
01
Advancing construction and repairing techniques with liquid metals
Researchers are looking at the effects of microgravity on the liquid metals formed during brazing, a technology used to bond materials at temperatures above 450 degrees Celsius. The Brazing of Aluminum alloys In Space (BRAINS)experiment aboard the International Space Station studies how alloys join with a range of other materials, such as ceramics or other metals.
In space, brazing could be used to construct vehicles, habitats, and other systems needed for space missions, and repair them if damaged. Advanced brazing technologies discovered in space may also be used in the construction and repair of structures on Earth.
02
Improving materials used for high-powered lasers
Another study on the space station is looking at the growth of semiconductor crystals based on Zinc selenide (ZnSe) in microgravity. ZnSe is an important semiconductor used on Earth for optical devices and infrared lasers.
Researchers are investigating the impact of microgravity on the growth of these crystals and comparing the results to those grown on Earth. A better understanding of the impact of microgravity on crystal growth could open the door to expanded commercial use of space.
03
Researching ways to make stronger metal
Metal alloys, which are created by combining two or more metallic elements, are used in everything from hardware to kitchen appliances, automobiles, and even the space station itself. Alloys are created by cooling a liquid metal until it hardens into a solid.
Researchers on the space station are investigating how metal alloys melt and take shape in a controlled microgravity environment. While brazing aims to repair or bond two separate materials, this experiment looks at casting or molding things from liquid metals. In metal castings, the solid grows by forming millions of snowflake-like crystals called dendrites. The shape of the dendrites affects the strength of the metal alloys.
Findings are expected to significantly impact our ability to produce metals with greater strength, for both space and on Earth applications.
04
Exploring stability and mechanics of foams and bubbly liquids
Studying how foams and bubbly liquids evolve in microgravity over time is another important NASA investigation. These experiments will provide guidance for how to control the flow and separation of bubbly liquids. This knowledge is crucial for developing a water recovery and recycling device for future space exploration to Mars.
On Earth, foams are found in everything from food and cosmetics to paper and petroleum. A better understanding of their stability and mechanics is important for creating sustainable, more efficient processes and improved materials.
05
Improving performance and lowering cost of “superglass”
Scientists are conducting experiments on supercooled metal oxides (space soil and rock) to better understand how molten materials can be processed in microgravity. Manufacturing new products in space is critical to long-term efforts to develop habitats in space and on other planets. It will require the use of available resources in space, including soil and rocks.
Data from the research also has far-reaching implications on Earth. It could help improve the performance and lower the cost of materials that are used in the production of cell phone displays, lasers, and glass for automobiles.
06
Advancing 3D printing and manufacturing through “soft matter” research
Space exploration to Mars and beyond will require astronauts to have the ability to build new equipment and materials in space. To make that a reality, space station researchers conducted a number of experiments looking at the behavior of colloids, or “soft matter,” in a microgravity environment.
This research could have a variety of applications on Earth, including the development of chemical energy, improvements to communications technologies, and enhancements to photonic materials used to control and manipulate light.
NASA’s Biological and Physical Sciences Division pioneers scientific discovery and enables exploration by using space environments to conduct investigations not possible on Earth. Studying biological and physical phenomenon under extreme conditions allows researchers to advance the fundamental scientific knowledge required to go farther and stay longer in space, while also benefitting life on Earth.
On Dec. 19, 2024, NASA released two amendments to the NASA Research Announcement Research Opportunities in Space and Earth Sciences (ROSES) 2024 (NNH24ZDA001N) to announce the E.9 Space Biology: Research Studies and E.12 Physical Sciences Research Studies program elements.
For Precision Health-focused studies, investigators may propose to use any non-primate animal model system and any appropriate cell/tissue culture/microphysiological system/organoid or microbial models that are supported by the chosen platform.
For Space Crop-focused studies, applicants may propose to use any plant, relevant microbe, and/or plant and microbe model system(s) that is (are) supported by the chosen platform.
The E.9 Space Biology: Research Studies opportunity includes five different Project Types: Research Investigations, Early Career Research Investigations, New NASA Investigators, OSDR Analytical Investigations, and Tissue Sharing Investigations. Specific requirements for each of these Project Types are described in the program element text. Questions concerning E.9 Space Biology: Research Studies may be directed to Lynn Harrison (for Precision Health) and Elison Blancaflor (for Space Crops) at nasa-spacebiology@mail.nasa.gov.
Physical Sciences Proposals
E.12 Physical Sciences: Research Studies solicits proposals to investigate physical phenomena in the absence of gravity and fundamental laws that describe the universe, and applied research that contributes to the basic understanding of processes underlying space exploration technologies.
The Physical Sciences program is divided into two key goals: Foundations and Quantum Leaps. Foundations focuses on understanding the behavior of fluids, combustion, soft matter, and materials in the spaceflight environment. Quantum Leaps aims to probe the very nature of the universe using exquisitely precise space-based quantum sensors to test the Einstein equivalence principle, dark sector physics, and the nature of fundamental physical constants.
The E.12 Physical Sciences: Research Studies opportunity will include four different Project Types: Research Investigations, New NASA Investigators, Physical Sciences Informatics, and Fundamental Physics Investigations. Specific requirements for each of these Project Types are described in detail in the program element text. Questions concerning E.12 Physical Sciences Research Studies may be directed to Brad Carpenter (regarding Foundations and PSI) or Mike Robinson (regarding Quantum Leaps) by writing to BPS-PhysicalSciences@nasaprs.com.
Town Hall
A pre-proposer’s townhall for applicants interested in submitting a proposal to these program elements will be held virtually on Jan. 22, 2025, at 3 p.m. Eastern Time. Meeting information will be posted on the NSPIRES page for each of the program elements under “Other Documents.”
Proposals to these program elements shall be submitted via a two-step process
Step-1 proposals must be submitted by Feb. 4, 2025
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