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By NASA
Flight Engineer Joe Acaba works in the U.S. Destiny laboratory module on the International Space Station, setting up hardware for the Zero Boil-Off Tank (ZBOT) experiment. Joe Acaba Space missions rely on cryogenic fluids — extremely cold liquids like liquid hydrogen and oxygen — for both propulsion and life support systems. These fuels must be kept at ultra-low cryogenic temperatures to remain in liquid form; however, solar heating and other sources of heat increase the rate of evaporation of the liquid and cause the pressure in the storage tank to increase. Current storage methods require venting the cryogenic propellant to space to control the pressure in fuel tanks.
NASA’s Zero Boil-Off Tank Noncondensables (ZBOT-NC) experiment is the continuation of Zero Boil-Off studies gathering crucial data to optimize fuel storage systems for space missions. The experiment will launch aboard Northrop Grumman’s 23rd resupply mission to the International Space Station.
When Cold Fuel Gets Too Warm
Even with multilayer insulation, heat unavoidably seeps into cryogenic fuel tanks from surrounding structures and the space environment, causing an increase in the liquid temperature and an associated increase in the evaporation rate. In turn, the pressure inside the tank increases. This process is called “boil-off” and the increase in tank pressure is referred to as “self-pressurization.”
Venting excess gas to the environment or space when this process occurs is highly undesirable and becomes mission-critical on extended journeys. If crew members used current fuel storage methods for a years-long Mars expedition, all propellant might be lost to boil-off before the trip ends.
NASA’s ZBOT experiments are investigating active pressure control methods to eliminate wasteful fuel venting. Specifically, active control through the use of jet mixing and other techniques are being evaluated and tested in the ZBOT series of experiments.
The Pressure Control Problem
ZBOT-NC further studies how noncondensable gases (NCGs) affect fuel tank behavior when present in spacecraft systems. NCGs don’t turn into liquid under the tank’s operating conditions and can affect tank pressure.
The investigation, which is led out of Glenn Research Center, will operate inside the Microgravity Science Glovebox aboard the space station to gather data on how NCGs affect volatile liquid behavior in microgravity. It’s part of an effort to advance cryogenic fluid management technologies and help NASA better understand low-gravity fluid behavior.
Researchers will measure pressure and temperature as they study how these gases change evaporation and condensation rates. Previous studies indicate the gases create barriers that could reduce a tank’s ability to maintain proper pressure control — a potentially serious issue for extended space missions.
How this benefits space exploration
The research directly supports Mars missions and other long-duration space travel by helping engineers design more efficient fuel storage systems and future space depots. The findings may also benefit scientific instruments on space telescopes and probes that rely on cryogenic fluids to maintain the extremely low temperatures needed for operation.
How this benefits humanity
The investigation could improve tank design models for medical, industrial, and energy production applications that depend on long-term cryogenic storage on Earth.
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Biological & Physical Sciences Division
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.
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By NASA
NASA science and American industry have worked hand-in-hand for more than 60 years, transforming novel technologies created with NASA research into commercial products like cochlear implants, memory-foam mattresses, and more. Now, a NASA-funded device for probing the interior of storm systems has been made a key component of commercial weather satellites.
The novel atmospheric sounder was originally developed for NASA’s TROPICS (short for Time-Resolved Observations of Precipitation structure and storm Intensity with a Constellation of SmallSats), which launched in 2023. Boston-based weather technology company Tomorrow.io integrated the same instrument design into some of its satellites.
NASA’s TROPICS instrument. TROPICS pioneered a novel, compact atmospheric sound now flying aboard a fleet of commercial small satellites created by the weather technology company Tomorrow.io.Credit: Blue Canyon Technologies Atmospheric sounders allow researchers to gather data describing humidity, temperature, and wind speed — important factors for weather forecasting and atmospheric analysis. From low-Earth orbit, these devices help make air travel safer, shipping more efficient, and severe weather warnings more reliable.
Novel tools for Observing Storm Systems
In the early 2000s, meteorologists and atmospheric chemists were eager to find a new science tool that could peer deep inside storm systems and do so multiple times a day. At the same time, CubeSat constellations (groupings of satellites each no larger than a shoebox) were emerging as promising, low-cost platforms for increasing the frequency with which individual sensors could pass over fast-changing storms, which improves the accuracy of weather models.
The challenge was to create an instrument small enough to fit aboard a satellite the size of a toaster, yet powerful enough to observe the innermost mechanisms of storm development. Preparing these technologies required years of careful development that was primarily supported by NASA’s Earth Science Division.
William Blackwell and his team at MIT Lincoln Laboratory in Cambridge, Massachusetts, accepted this challenge and set out to miniaturize vital components of atmospheric sounders. “These were instruments the size of a washing machine, flying on platforms the size of a school bus,” said Blackwell, the principal investigator for TROPICS. “How in the world could we shrink them down to the size of a coffee mug?”
With a 2010 award from NASA’s Earth Science Technology Office (ESTO), Blackwell’s team created an ultra-compact microwave receiver, a component that can sense the microwave radiation within the interior of storms.
The Lincoln Lab receiver weighed about a pound and took up less space than a hockey puck. This innovation paved the way for a complete atmospheric sounder instrument small enough to fly aboard a CubeSat. “The hardest part was figuring out how to make a compact back-end to this radiometer,” Blackwell said. “So without ESTO, this would not have happened. That initial grant was critical.”
In 2023, that atmospheric sounder was sent into space aboard four TROPICS CubeSats, which have been collecting torrents of data on the interior of severe storms around the world.
Transition to Industry
By the time TROPICS launched, Tomorrow.io developers knew they wanted Blackwell’s microwave receiver technology aboard their own fleet of commercial weather satellites. “We looked at two or three different options, and TROPICS was the most capable instrument of those we looked at,” said Joe Munchak, a senior atmospheric data scientist at Tomorrow.io.
In 2022, the company worked with Blackwell to adapt his team’s design into a CubeSat platform about twice the size of the one used for TROPICS. A bigger platform, Blackwell explained, meant they could bolster the sensor’s capabilities.
“When we first started conceptualizing this, the 3-unit CubeSat was the only game in town. Now we’re using a 6-unit CubeSat, so we have room for onboard calibration,” which improves the accuracy and reliability of gathered data, Blackwell said.
Tomorrow.io’s first atmospheric sounders, Tomorrow-S1 and Tomorrow-S2, launched in 2024. By the end of 2025, the company plans to have a full constellation of atmospheric sounders in orbit. The company also has two radar instruments that were launched in 2023 and were influenced by NASA’s RainCube instrument — the first CubeSat equipped with an active precipitation radar.
More CubeSats leads to more accurate weather data because there are more opportunities each day — revisits — to collect data. “With a fleet size of 18, we can easily get our revisit rate down to under an hour, maybe even 40 to 45 minutes in most places. It has a huge impact on short-term forecasts,” Munchak said.
Having access to an atmospheric sounder that had already flown in space and had more than 10 years of testing was extremely useful as Tomorrow.io planned its fleet. “It would not have been possible to do this nearly as quickly or nearly as affordably had NASA not paved the way,” said Jennifer Splaingard, Tomorrow.io’s senior vice president for space and sensors.
A Cycle of Innovation
The relationship between NASA and industry is symbiotic. NASA and its grantees can drive innovation and test new tools, equipping American businesses with novel technologies they may otherwise be unable to develop on their own. In exchange, NASA gains access to low-cost data sets that can supplement information gathered through its larger science missions.
Tomorrow.io was among eight companies selected by NASA’s Commercial SmallSat Data Acquisition (CSDA) program in September 2024 to equip NASA with data that will help improve weather forecasting models. “It really is a success story of technology transfer. It’s that sweet spot, where the government partners with tech companies to really take an idea, a proven concept, and run with it,” Splaingard said.
By Gage Taylor
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Sep 02, 2025 Related Terms
Earth Hurricanes & Typhoons TROPICS (Time-Resolved Observations of Precipitation Structure and Storm Intensity with a Constellation of Smallsats) View the full article
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Dwarf planet Ceres is shown in these enhanced-color renderings that use images from NASA’s Dawn mission. New thermal and chemicals models that rely on the mission’s data indicate Ceres may have long ago had conditions suitable for life.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA The dwarf planet is cold now, but new research paints a picture of Ceres hosting a deep, long-lived energy source that may have maintained habitable conditions in the past.
New NASA research has found that Ceres may have had a lasting source of chemical energy: the right types of molecules needed to fuel some microbial metabolisms. Although there is no evidence that microorganisms ever existed on Ceres, the finding supports theories that this intriguing dwarf planet, which is the largest body in the main asteroid belt between Mars and Jupiter, may have once had conditions suitable to support single-celled lifeforms.
Science data from NASA’s Dawn mission, which ended in 2018, previously showed that the bright, reflective regions on Ceres’ surface are mostly made of salts left over from liquid that percolated up from underground. Later analysis in 2020 found that the source of this liquid was an enormous reservoir of brine, or salty water, below the surface. In other research, the Dawn mission also revealed evidence that Ceres has organic material in the form of carbon molecules — essential, though not sufficient on its own, to support microbial cells.
The presence of water and carbon molecules are two critical pieces of the habitability puzzle on Ceres. The new findings offer the third: a long-lasting source of chemical energy in Ceres’ ancient past that could have made it possible for microorganisms to survive. This result does not mean that Ceres had life, but rather, that there likely was “food” available should life have ever arisen on Ceres.
This illustration depicts the interior of dwarf planet Ceres, including the transfer of water and gases from the rocky core to a reservoir of salty water. Carbon dioxide and methane are among the molecules carrying chemical energy beneath Ceres’ surface.NASA/JPL-Caltech In the study, published in Science Advances on Aug. 20, the authors built thermal and chemical models mimicking the temperature and composition of Ceres’ interior over time. They found that 2.5 billion years or so ago, Ceres’ subsurface ocean may have had a steady supply of hot water containing dissolved gases traveling up from metamorphosed rocks in the rocky core. The heat came from the decay of radioactive elements within the dwarf planet’s rocky interior that occurred when Ceres was young — an internal process thought to be common in our solar system.
“On Earth, when hot water from deep underground mixes with the ocean, the result is often a buffet for microbes — a feast of chemical energy. So it could have big implications if we could determine whether Ceres’ ocean had an influx of hydrothermal fluid in the past,” said Sam Courville, lead author of the study. Now based at Arizona State University in Tempe, he led the research while working as an intern at NASA’s Jet Propulsion Laboratory in Southern California, which also managed the Dawn mission.
Catching Chill
The Ceres we know today is unlikely to be habitable. It is cooler, with more ice and less water than in the past. There is currently insufficient heat from radioactive decay within Ceres to keep the water from freezing, and what liquid remains has become a concentrated brine.
The period when Ceres would most likely have been habitable was between a half-billion and 2 billion years after it formed (or about 2.5 billion to 4 billion years ago), when its rocky core reached its peak temperature. That’s when warm fluids would have been introduced into Ceres’ underground water.
The dwarf planet also doesn’t have the benefit of present-day internal heating generated by the push and pull of orbiting a large planet, like Saturn’s moon Enceladus and Jupiter’s moon Europa do. So Ceres’ greatest potential for habitability-fueling energy was in the past.
This result has implications for water-rich objects throughout the outer solar system, too. Many of the other icy moons and dwarf planets that are of similar size to Ceres (about 585 miles, or 940 kilometers, in diameter) and don’t have significant internal heating from the gravitational pull of planets could have also had a period of habitability in their past.
More About Dawn
A division of Caltech in Pasadena, JPL managed Dawn’s mission for NASA’s Science Mission Directorate in Washington. Dawn was a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. JPL was responsible for overall Dawn mission science. Northrop Grumman in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute were international partners on the mission team.
For a complete list of mission participants, visit:
https://solarsystem.nasa.gov/missions/dawn/overview/
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Gretchen McCartney
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Last Updated Aug 20, 2025 Related Terms
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Cloud cover can keep optical instruments on satellites from clearly capturing Earth’s surface. Still in testing, JPL’s Dynamic Targeting uses AI to avoid imaging clouds, yielding a higher proportion of usable data, and to focus on phenomena like this 2015 volcanic eruption in Indonesia Landsat 8 captured.NASA/USGS A technology called Dynamic Targeting could enable spacecraft to decide, autonomously and within seconds, where to best make science observations from orbit.
In a recent test, NASA showed how artificial intelligence-based technology could help orbiting spacecraft provide more targeted and valuable science data. The technology enabled an Earth-observing satellite for the first time to look ahead along its orbital path, rapidly process and analyze imagery with onboard AI, and determine where to point an instrument. The whole process took less than 90 seconds, without any human involvement.
Called Dynamic Targeting, the concept has been in development for more than a decade at NASA’s Jet Propulsion Laboratory in Southern California. The first of a series of flight tests occurred aboard a commercial satellite in mid-July. The goal: to show the potential of Dynamic Targeting to enable orbiters to improve ground imaging by avoiding clouds and also to autonomously hunt for specific, short-lived phenomena like wildfires, volcanic eruptions, and rare storms.
This graphic shows how JPL’s Dynamic Targeting uses a lookahead sensor to see what’s on a satellite’s upcoming path. Onboard algorithms process the sensor’s data, identifying clouds to avoid and targets of interest for closer observation as the satellite passes overhead.NASA/JPL-Caltech “The idea is to make the spacecraft act more like a human: Instead of just seeing data, it’s thinking about what the data shows and how to respond,” says Steve Chien, a technical fellow in AI at JPL and principal investigator for the Dynamic Targeting project. “When a human sees a picture of trees burning, they understand it may indicate a forest fire, not just a collection of red and orange pixels. We’re trying to make the spacecraft have the ability to say, ‘That’s a fire,’ and then focus its sensors on the fire.”
Avoiding Clouds for Better Science
This first flight test for Dynamic Targeting wasn’t hunting specific phenomena like fires — that will come later. Instead, the point was avoiding an omnipresent phenomenon: clouds.
Most science instruments on orbiting spacecraft look down at whatever is beneath them. However, for Earth-observing satellites with optical sensors, clouds can get in the way as much as two-thirds of the time, blocking views of the surface. To overcome this, Dynamic Targeting looks 300 miles (500 kilometers) ahead and has the ability to distinguish between clouds and clear sky. If the scene is clear, the spacecraft images the surface when passing overhead. If it’s cloudy, the spacecraft cancels the imaging activity to save data storage for another target.
“If you can be smart about what you’re taking pictures of, then you only image the ground and skip the clouds. That way, you’re not storing, processing, and downloading all this imagery researchers really can’t use,” said Ben Smith of JPL, an associate with NASA’s Earth Science Technology Office, which funds the Dynamic Targeting work. “This technology will help scientists get a much higher proportion of usable data.”
How Dynamic Targeting Works
The testing is taking place on CogniSAT-6, a briefcase-size CubeSat that launched in March 2024. The satellite — designed, built, and operated by Open Cosmos — hosts a payload designed and developed by Ubotica featuring a commercially available AI processor. While working with Ubotica in 2022, Chien’s team conducted tests aboard the International Space Station running algorithms similar to those in Dynamic Targeting on the same type of processor. The results showed the combination could work for space-based remote sensing.
Since CogniSAT-6 lacks an imager dedicated to looking ahead, the spacecraft tilts forward 40 to 50 degrees to point its optical sensor, a camera that sees both visible and near-infrared light. Once look-ahead imagery has been acquired, Dynamic Targeting’s advanced algorithm, trained to identify clouds, analyzes it. Based on that analysis, the Dynamic Targeting planning software determines where to point the sensor for cloud-free views. Meanwhile, the satellite tilts back toward nadir (looking directly below the spacecraft) and snaps the planned imagery, capturing only the ground.
This all takes place in 60 to 90 seconds, depending on the original look-ahead angle, as the spacecraft speeds in low Earth orbit at nearly 17,000 mph (7.5 kilometers per second).
What’s Next
With the cloud-avoidance capability now proven, the next test will be hunting for storms and severe weather — essentially targeting clouds instead of avoiding them. Another test will be to search for thermal anomalies like wildfires and volcanic eruptions. The JPL team developed unique algorithms for each application.
“This initial deployment of Dynamic Targeting is a hugely important step,” Chien said. “The end goal is operational use on a science mission, making for a very agile instrument taking novel measurements.”
There are multiple visions for how that could happen — possibly even on spacecraft exploring the solar system. In fact, Chien and his JPL colleagues drew some inspiration for their Dynamic Targeting work from another project they had also worked on: using data from ESA’s (the European Space Agency’s) Rosetta orbiter to demonstrate the feasibility of autonomously detecting and imaging plumes emitted by comet 67P/Churyumov-Gerasimenko.
On Earth, adapting Dynamic Targeting for use with radar could allow scientists to study dangerous extreme winter weather events called deep convective ice storms, which are too rare and short-lived to closely observe with existing technologies. Specialized algorithms would identify these dense storm formations with a satellite’s look-ahead instrument. Then a powerful, focused radar would pivot to keep the ice clouds in view, “staring” at them as the spacecraft speeds by overhead and gathers a bounty of data over six to eight minutes.
Some ideas involve using Dynamic Targeting on multiple spacecraft: The results of onboard image analysis from a leading satellite could be rapidly communicated to a trailing satellite, which could be tasked with targeting specific phenomena. The data could even be fed to a constellation of dozens of orbiting spacecraft. Chien is leading a test of that concept, called Federated Autonomous MEasurement, beginning later this year.
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Last Updated Jul 24, 2025 Related Terms
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By NASA
NASA Glenn Research Center’s Thermal Energy Conversion Branch team and the University of Leicester’s Space Nuclear Power team pose for a photo at the center in Cleveland following a successful test in January 2025.Credit: NASA/Jef Janis To explore the unknown in deep space, millions of miles away from Earth, it’s crucial for spacecraft to have ample power. NASA’s radioisotope power systems (RPS) are a viable option for these missions and have been used for over 60 years, including for the agency’s Voyager spacecraft and Perseverance Mars rover. These nuclear batteries provide long-term electrical power for spacecraft and science instruments using heat produced by the natural radioactive decay of radioisotopes. Now, NASA is testing a new type of RPS heat source fuel that could become an additional option for future long-duration journeys to extreme environments.
Historically, the radioisotope plutonium-238 (plutonium oxide) has been NASA’s RPS heat source fuel of choice, but americium-241 has been a source of interest for the past two decades in Europe. In January, the Thermal Energy Conversion Branch at NASA’s Glenn Research Center in Cleveland and the University of Leicester, based in the United Kingdom, partnered through an agreement to put this new option to the test.
One method to generate electricity from radioisotope heat sources is the free-piston Stirling convertor. This is a heat engine that converts thermal energy into electrical energy. However, instead of a crankshaft to extract power, pistons float freely within the engine. It could operate for decades continuously without wear, as it does not have piston rings or rotating bearings that will eventually wear out. Thus, a Stirling convertor could generate more energy, allowing more time for exploration in deep space. Researchers from the University of Leicester — who have been leaders in the development of americium RPS and heater units for more than 15 years — and NASA worked to test the capabilities of a Stirling generator testbed powered by two electrically heated americium-241 heat source simulators.
“The concept started as just a design, and we took it all the way to the prototype level: something close to a flight version of the generator,” said Salvatore Oriti, mechanical engineer at Glenn. “The more impressive part is how quickly and inexpensively we got it done, only made possible by a great synergy between the NASA and University of Leicester teams. We were on the same wavelength and shared the same mindset.”
Salvatore Oriti, mechanical engineer in the Thermal Energy Conversion Branch at NASA’s Glenn Research Center in Cleveland, adjusts the Stirling testbed in preparation for testing at the center in January 2025.Credit: NASA/Jef Janis The university provided the heat source simulators and generator housing. The heat source simulator is the exact size and shape of their real americium-241 heat source, but it uses embedded electric heaters to create an equivalent amount of heat to simulate the decay of americium fuel and therefore drive generator operation. The Stirling Research Lab at Glenn provided the test station, Stirling convertor hardware, and support equipment.
“A particular highlight of this (testbed) design is that it is capable of withstanding a failed Stirling convertor without a loss of electrical power,” said Hannah Sargeant, research fellow at the University of Leicester. “This feature was demonstrated successfully in the test campaign and highlights the robustness and reliability of an Americium-Radioisotope Stirling Generator for potential future spaceflight missions, including long-duration missions that could operate for many decades.”
The test proved the viability of an americium-fueled Stirling RPS, and performance and efficiency targets were successfully met. As for what’s next, the Glenn team is pursuing the next version of the testbed that will be lower mass, higher fidelity, and undergo further environmental testing.
“I was very pleased with how smoothly everything went,” Oriti said of the test results. “Usually in my experience, you don’t accomplish everything you set out to, but we did that and more. We plan to continue that level of success in the future.”
For more information on NASA’s RPS programs, visit:
https://science.nasa.gov/rps
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