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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A ship plows through rough seas in the Bering Sea in the aftermath of Typhoon Tip, one of the largest hurricanes on record. The Sentinel-6B satellite will provide data crucial to forecasting sea states, information that can help ships avoid danger. CC BY 2.0 NOAA/Commander Richard Behn Sea surface height data from the Sentinel-6B satellite, led by NASA and ESA, will help with the development of marine weather forecasts, alerting ships to possible dangers.
Because most global trade travels by ship, accurate, timely ocean forecasts are essential. These forecasts provide crucial information about storms, high winds, and rough water, and they depend on measurements provided by instruments in the ocean and by satellites including Sentinel-6B, a joint mission led by NASA and ESA (European Space Agency) that will provide essential sea level and other ocean data after it launches this November.
The satellite will eventually take over from its twin, Sentinel-6 Michael Freilich, which launched in 2020. Both satellites have an altimeter instrument that measures sea levels, wind speeds, and wave heights, among other characteristics, which meteorologists feed into models that produce marine weather forecasts. Those forecasts provide information on the state of the ocean as well as the changing locations of large currents like the Gulf Stream. Dangerous conditions can result when waves interact with such currents, putting ships at risk.
“Building on NASA’s long legacy of satellite altimetry data and its real-world impact on shipping operations, Sentinel-6B will soon take on the vital task of improving ocean and weather forecasts to help keep ships, their crews, and cargo safe”, said Nadya Vinogradova Shiffer, lead program scientist at NASA Headquarters in Washington.
Sentinel-6 Michael Freilich and Sentinel-6B are part of the Sentinel-6/Jason-CS (Continuity of Service) mission, the latest in a series of ocean-observing radar altimetry missions that have monitored Earth’s changing seas since the early 1990s. Sentinel-6/Jason-CS is a collaboration between NASA, ESA, the European Union, EUMETSAT (European Organisation for the Exploitation of Meteorological Satellites), and NOAA (U.S. National Oceanic and Atmospheric Administration). The European Commission provided funding support, and the French space agency CNES (Centre National d’Études Spatiales) contributed technical support.
Keeping current
“The ocean is getting busier, but it’s also getting more dangerous,” said Avichal Mehra, deputy director of the Ocean Prediction Center at the National Weather Service in College Park, Maryland. He and his colleagues produce marine weather forecasts using data from ocean-based instruments as well as complementary measurements from five satellites, including Sentinel-6 Michael Freilich. Among those measurements: sea level, wave height, and wind speed. The forecasters derive the location of large currents from changes in sea level.
One of the planet’s major currents, the Gulf Stream is located off the southeastern coast of the United States, but its exact position varies. “Ships will actually change course depending on where the Gulf Stream is and the direction of the waves,” said Mehra. “There have been instances where, in calm conditions, waves interacting with the Gulf Stream have caused damage or the loss of cargo containers on ships.”
Large, warm currents like the Gulf Stream can have relatively sharp boundaries since they are generally higher than their surroundings. Water expands as it warms, so warm seawater is taller than cooler water. If waves interact with these currents in a certain way, seas can become extremely rough, presenting a hazard to even the largest ships.
“Satellite altimeters are the only reliable measurement we have of where these big currents can be,” said Deirdre Byrne, sea surface height team lead at NOAA in College Park.
There are hundreds of floating sensors scattered about the ocean that could pick up parts of where such currents are located, but these instruments are widely dispersed and limited in the area they measure at any one time. Satellites like Sentinel-6B offer greater spatial coverage, measuring areas that aren’t regularly monitored and providing essential information for the forecasts that ships need.
Consistency is key
Sentinel-6B won’t just help marine weather forecasts through its near-real-time data, though. It will also extend a long-term dataset featuring more than 30 years of sea level measurements, just as Sentinel-6 Michael Freilich does today.
“Since 1992, we have launched a series of satellites that have provided consistent sea level observations from the same orbit in space. This continuity allows each new mission to be calibrated against its predecessors, providing measurements with centimeter-level accuracy that don’t drift over time,” said Severine Fournier, Sentinel-6B deputy project scientist at NASA’s Jet Propulsion Laboratory in Southern California.
This long-running, repeated measurement has turned this dataset into the gold standard sea level measurement from space — a reference against which data from other sea level satellites is checked. It also serves as a baseline, giving forecasters a way to tell what ocean conditions have looked like over time and how they are changing now. “This kind of data can’t be easily replaced,” said Mehra.
More about Sentinel-6B
Sentinel-6/Jason-CS was jointly developed by ESA, EUMETSAT, NASA, and NOAA, with funding support from the European Commission and technical support from CNES.
A division of Caltech in Pasadena, JPL contributed three science instruments for each Sentinel-6 satellite: the Advanced Microwave Radiometer, the Global Navigation Satellite System – Radio Occultation, and the Laser Retroreflector Array. NASA is also contributing launch services, ground systems supporting operation of the NASA science instruments, the science data processors for two of these instruments, and support for the U.S. members of the international Ocean Surface Topography and Sentinel-6 science teams.
For more about Sentinel-6/Jason-CS, visit:
https://sealevel.jpl.nasa.gov/missions/jason-cs-sentinel-6
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Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
626-491-1943 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
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Last Updated Sep 11, 2025 Related Terms
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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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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
Explore Webb Science James Webb Space Telescope (JWST) NASA’s Webb Observes Immense… Webb News Latest News Latest Images Webb’s Blog Awards X (offsite – login reqd) Instagram (offsite – login reqd) Facebook (offsite- login reqd) Youtube (offsite) Overview About Who is James Webb? Fact Sheet Impacts+Benefits FAQ Webb Timeline Science Overview and Goals Early Universe Galaxies Over Time Star Lifecycle Other Worlds Science Explainers Observatory Overview Launch Deployment Orbit Mirrors Sunshield Instrument: NIRCam Instrument: MIRI Instrument: NIRSpec Instrument: FGS/NIRISS Optical Telescope Element Backplane Spacecraft Bus Instrument Module Multimedia About Webb Images Images Videos What is Webb Observing? 3d Webb in 3d Solar System Podcasts Webb Image Sonifications Webb’s First Images Team International Team People Of Webb More For the Media For Scientists For Educators For Fun/Learning 6 Min Read NASA’s Webb Observes Immense Stellar Jet on Outskirts of Our Milky Way
Webb’s image of the enormous stellar jet in Sh2-284 provides evidence that protostellar jets scale with the mass of their parent stars—the more massive the stellar engine driving the plasma, the larger the resulting jet. Full image shown below. Credits:
Image: NASA, ESA, CSA, STScI, Yu Cheng (NAOJ); Image Processing: Joseph DePasquale (STScI) A blowtorch of seething gasses erupting from a volcanically growing monster star has been captured by NASA’s James Webb Space Telescope. Stretching across 8 light-years, the length of the stellar eruption is approximately twice the distance between our Sun and the next nearest stars, the Alpha Centauri system. The size and strength of this particular stellar jet, located in a nebula known as Sharpless 2-284 (Sh2-284 for short), qualifies it as rare, say researchers.
Streaking across space at hundreds of thousands of miles per hour, the outflow resembles a double-bladed dueling lightsaber from the Star Wars films. The central protostar, weighing as much as ten of our Suns, is located 15,000 light-years away in the outer reaches of our galaxy.
The Webb discovery was serendipitous. “We didn’t really know there was a massive star with this kind of super-jet out there before the observation. Such a spectacular outflow of molecular hydrogen from a massive star is rare in other regions of our galaxy,” said lead author Yu Cheng of the National Astronomical Observatory of Japan.
Image A: Stellar Jet in Sh2-284 (NIRCam Image)
Webb’s image of the enormous stellar jet in Sh2-284 provides evidence that protostellar jets scale with the mass of their parent stars—the more massive the stellar engine driving the plasma, the larger the resulting jet. Image: NASA, ESA, CSA, STScI, Yu Cheng (NAOJ); Image Processing: Joseph DePasquale (STScI) This unique class of stellar fireworks are highly collimated jets of plasma shooting out from newly forming stars. Such jetted outflows are a star’s spectacular “birth announcement” to the universe. Some of the infalling gas building up around the central star is blasted along the star’s spin axis, likely under the influence of magnetic fields.
Today, while hundreds of protostellar jets have been observed, these are mainly from low-mass stars. These spindle-like jets offer clues into the nature of newly forming stars. The energetics, narrowness, and evolutionary time scales of protostellar jets all serve to constrain models of the environment and physical properties of the young star powering the outflow.
“I was really surprised at the order, symmetry, and size of the jet when we first looked at it,” said co-author Jonathan Tan of the University of Virginia in Charlottesville and Chalmers University of Technology in Gothenburg, Sweden.
Its detection offers evidence that protostellar jets must scale up with the mass of the star powering them. The more massive the stellar engine propelling the plasma, the larger the gusher’s size.
The jet’s detailed filamentary structure, captured by Webb’s crisp resolution in infrared light, is evidence the jet is plowing into interstellar dust and gas. This creates separate knots, bow shocks, and linear chains.
The tips of the jet, lying in opposite directions, encapsulate the history of the star’s formation. “Originally the material was close into the star, but over 100,000 years the tips were propagating out, and then the stuff behind is a younger outflow,” said Tan.
Outlier
At nearly twice the distance from the galactic center as our Sun, the host proto-cluster that’s home to the voracious jet is on the periphery of our Milky Way galaxy.
Within the cluster, a few hundred stars are still forming. Being in the galactic hinterlands means the stars are deficient in heavier elements beyond hydrogen and helium. This is measured as metallicity, which gradually increases over cosmic time as each passing stellar generation expels end products of nuclear fusion through winds and supernovae. The low metallicity of Sh2-284 is a reflection of its relatively pristine nature, making it a local analog for the environments in the early universe that were also deficient in heavier elements.
“Massive stars, like the one found inside this cluster, have very important influences on the evolution of galaxies. Our discovery is shedding light on the formation mechanism of massive stars in low metallicity environments, so we can use this massive star as a laboratory to study what was going on in earlier cosmic history,” said Cheng.
Unrolling Stellar Tapestry
Stellar jets, which are powered by the gravitational energy released as a star grows in mass, encode the formation history of the protostar.
“Webb’s new images are telling us that the formation of massive stars in such environments could proceed via a relatively stable disk around the star that is expected in theoretical models of star formation known as core accretion,” said Tan. “Once we found a massive star launching these jets, we realized we could use the Webb observations to test theories of massive star formation. We developed new theoretical core accretion models that were fit to the data, to basically tell us what kind of star is in the center. These models imply that the star is about 10 times the mass of the Sun and is still growing and has been powering this outflow.”
For more than 30 years, astronomers have disagreed about how massive stars form. Some think a massive star requires a very chaotic process, called competitive accretion.
In the competitive accretion model, material falls in from many different directions so that the orientation of the disk changes over time. The outflow is launched perpendicularly, above and below the disk, and so would also appear to twist and turn in different directions.
“However, what we’ve seen here, because we’ve got the whole history – a tapestry of the story – is that the opposite sides of the jets are nearly 180 degrees apart from each other. That tells us that this central disk is held steady and validates a prediction of the core accretion theory,” said Tan.
Where there’s one massive star, there could be others in this outer frontier of the Milky Way. Other massive stars may not yet have reached the point of firing off Roman-candle-style outflows. Data from the Atacama Large Millimeter Array in Chile, also presented in this study, has found another dense stellar core that could be in an earlier stage of construction.
The paper has been accepted for publication in The Astrophysical Journal.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
To learn more about Webb, visit:
https://science.nasa.gov/webb
Related Information
View more: Webb images of other protostar outflows – HH 49/50, L483, HH 46/47, and HH 211
View more: Data visualization of protostar outflows – HH 49/50
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Explore the jets emitted by young stars in multiple wavelengths: ViewSpace Interactive
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Related Images & Videos
Stellar Jet in Sh2-284 (NIRCam Image)
Webb’s image of the enormous stellar jet in Sh2-284 provides evidence that protostellar jets scale with the mass of their parent stars–the more massive the stellar engine driving the plasma, the larger the resulting jet.
Stellar Jet in Sh2-284 (NIRCam Compass Image)
This image of the stellar jet in Sh2-284, captured by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera), shows compass arrows, scale bar, and color key for reference.
Immense Stellar Jet in Sh2-284
This video shows the relative size of two different protostellar jets imaged by NASA’s James Webb Space Telescope. The first image shown is an extremely large protostellar jet located in Sh2-284, 15,000 light-years away from Earth. The outflows from the massive central prot…
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Last Updated Sep 10, 2025 Location NASA Goddard Space Flight Center Contact Media Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov
Ray Villard
Space Telescope Science Institute
Baltimore, Maryland
Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland
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By NASA
NASA’s Perseverance Mars rover took this selfie on September 10, 2021, the 198th Martian day, or sol of its mission.Credit: NASA/JPL-Caltech NASA will host a news conference at 11 a.m. EDT Wednesday, to discuss the analysis of a rock sampled by the agency’s Perseverance Mars rover last year, which is the subject of a forthcoming science paper. The agency previously announced this event as a teleconference.
Watch the news conference on NASA’s YouTube channel and the agency’s website. Learn how to watch NASA content through a variety of platforms, including social media.
Participants include:
Acting NASA Administrator Sean Duffy NASA Associate Administrator Amit Kshatriya Nicky Fox, associate administrator, Science Mission Directorate, NASA Headquarters in Washington Lindsay Hays, senior scientist for Mars Exploration, Planetary Science Division, NASA Headquarters Katie Stack Morgan, Perseverance project scientist, NASA’s Jet Propulsion Laboratory in Southern California Joel Hurowitz, planetary scientist, Stony Brook University, New York To ask questions by phone, members of the media must RSVP no later than one hour before the start of the event to: rexana.v.vizza@jpl.nasa.gov. Media who registered for the earlier teleconference-only version of this event do not need to re-register. NASA’s media accreditation policy is available online.
The sample, called “Sapphire Canyon,” was collected in July 2024 from a set of rocky outcrops on the edges of Neretva Vallis, a river valley carved by water rushing into Jezero Crater long ago.
Since landing in the Red Planet’s Jezero Crater in February 2021, Perseverance has collected 30 samples. The rover still has six empty sample tubes to fill, and it continues to collect detailed information about geologic targets that it hasn’t sampled by using its abrasion tool. Among the rover’s science instruments is a weather station that provides environmental information for future human missions, as well as swatches of spacesuit material so that NASA can study how it fares on Mars.
Managed for NASA by Caltech, JPL built and manages operations of the Perseverance rover on behalf of the agency’s Science Mission Directorate as part of NASA’s Mars Exploration Program portfolio.
To learn more about Perseverance visit:
https://www.nasa.gov/perseverance
-end-
Bethany Stevens / Karen Fox
Headquarters, Washington
202-358-1600
bethany.c.stevens@nasa.gov / karen.c.fox@nasa.gov
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov
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Last Updated Sep 10, 2025 LocationNASA Headquarters Related Terms
Perseverance (Rover) Mars 2020 Planetary Science Division Science Mission Directorate
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By NASA
NASA’s Perseverance Mars rover took this selfie on September 10, 2021, the 198th Martian day, or sol of its mission. Credit: NASA/JPL-Caltech NASA will host a media teleconference at 11 a.m. EDT Wednesday, Sept. 10, to discuss the analysis of a rock sampled by the agency’s Perseverance Mars rover last year, which is the subject of a forthcoming science paper.
The sample, called “Sapphire Canyon,” was collected in July 2024 from a set of rocky outcrops on the edges of Neretva Vallis, a river valley carved by water rushing into Jezero Crater long ago.
Audio and visuals of the call will stream on the agency’s website at:
https://www.nasa.gov/live
Participants in the teleconference include:
Acting NASA Administrator Sean Duffy Nicky Fox, associate administrator, Science Mission Directorate, NASA Headquarters in Washington Lindsay Hays, Senior Scientist for Mars Exploration, Planetary Science Division, NASA Headquarters Katie Stack Morgan, Perseverance Project Scientist, NASA’s Jet Propulsion Laboratory in Southern California Joel Hurowitz, planetary scientist, Stony Brook University, New York To ask questions by phone, members of the media must RSVP no later than two hours before the start of the event to: rexana.v.vizza@jpl.nasa.gov. NASA’s media accreditation policy is available online.
Since landing in the Red Planet’s Jezero Crater in February 2021, Perseverance has collected 30 samples. The rover still has six empty sample tubes to fill, and it continues to collect detailed information about geologic targets that it hasn’t sampled by using its abrasion tool. Among the rover’s science instruments is a weather station that provides environmental information for future human missions, as well as swatches of spacesuit material so that NASA can study how it fares on Mars.
Managed for NASA by Caltech, JPL built and manages operations of the Perseverance rover on behalf of the agency’s Science Mission Directorate as part of NASA’s Mars Exploration Program portfolio.
To learn more about Perseverance visit:
https://www.nasa.gov/perseverance
-end-
Bethany Stevens / Karen Fox
Headquarters, Washington
202-358-1600
bethany.c.stevens@nasa.gov / karen.c.fox@nasa.gov
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov
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Last Updated Sep 08, 2025 LocationNASA Headquarters Related Terms
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