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Arctic Weather Satellite lifts off to set the stage for better forecasts
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By NASA
NASA Goddard MODIS Rapid Response Team During the morning of March 20, 2015, a total solar eclipse was visible from parts of Europe, and a partial solar eclipse from northern Africa and northern Asia. NASA’s Terra satellite passed over the Arctic Ocean on March 20 at 10:45 UTC (6:45 a.m. EDT) and captured the eclipse’s shadow over the clouds in the Arctic Ocean.
Terra launched 25 years ago on Dec. 18, 1999. Approximately the size of a small school bus, the Terra satellite carries five instruments that take coincident measurements of the Earth system: Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Clouds and Earth’s Radiant Energy System (CERES), Multi-angle Imaging Spectroradiometer (MISR), Measurements of Pollution in the Troposphere (MOPITT), and Moderate Resolution Imaging Spectroradiometer (MODIS).
On Nov. 28, 2024, one of Terra’s power-transmitting shunt units failed. A response team reviewed Terra’s status and discussed potential impacts and options. Consequently, the team placed ASTER into Safe Mode. As a result, ASTER data are not currently being collected. All other instruments continue uninterrupted.
Image Credit: NASA Goddard MODIS Rapid Response Team
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By NASA
NASA has taken a big step forward in how engineers will assemble and stack future SLS (Space Launch System) rockets for Artemis Moon missions inside the Vehicle Assembly Building (VAB) at the agency’s Kennedy Space Center in Florida.
The VAB’s High Bay 2 has been outfitted with new tooling to facilitate the vertical integration of the SLS core stage. That progress was on full display in mid-December when teams suspended the fully assembled core stage 225 feet in the air inside the high bay to complete vertical work before it is stacked on mobile launcher 1, allowing teams to continue solid rocket booster stacking simultaneously inside High Bay 3 for Artemis II.
The fully assembled SLS (Space Launch System) core stage for the Artemis II test flight is suspended 225 feet in the air inside the newly renovated High Bay 2 at Kennedy’s Vehicle Assembly Building. The core stage was lifted to enable engineers to complete work before it is stacked on mobile launcher 1 with other rocket elements. With the move to High Bay 2, technicians now have 360-degree tip to tail access to the core stage, both internally and externally.NASA With the move to High Bay 2, technicians with NASA and Boeing now have 360-degree tip to tail access to the core stage, both internally and externally. Michigan-based supplier Futuramic Tool and Engineering led the design and build of the Core Stage Vertical Integration Center tool that will hold the core stage in a vertical position.
“High Bay 2 tooling was originally scheduled to be complete for Artemis III. We had an opportunity to get it done earlier and that will put us in a good posture to complete work earlier than planned prior to moving the core stage for Artemis II into the full integrated stack over into in High Bay 3,” said Chad Bryant, deputy manager of the NASA SLS Stages Office. “This gives us an opportunity to go in and learn how to rotate, lift, and move the core stage into the high bay.”
This move also doubles the footprint of useable space within the VAB, giving engineers access to both High Bay 2 and High Bay 3 simultaneously, while also freeing up space at NASA’s Michoud Assembly Facility in New Orleans to continue work on the individual elements for future SLS core stages.
High Bay 2 has a long history of supporting NASA exploration programs: during Apollo, High Bay 2, one of four high bays inside the VAB, was used to stack the Saturn V rocket. During the Space Shuttle Program, the high bay was used for external tank checkout and storage and as an extra storage area for the shuttle.
Under the new assembly model beginning with Artemis III, all the major structures for the SLS core stage will continue to be fully produced and manufactured at NASA Michoud. Upon completion of manufacturing and thermal protection system application, the engine section will be shipped to Kennedy for final outfitting.
The 212-foot-tall SLS (Space Launch System) core stage for NASA Artemis II is seen being moved from a horizontal position to a vertical position in High Bay 2 at the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida. With the move to High Bay 2, NASA and Boeing technicians now have 360-degree access to the core stage both internally and externally. (NASA) “Core stage 3 marks a significant change in the way we build core stages,” said Steve Wofford, manager of the SLS Stages Office. “The vertical capability in High Bay 2 allows us to perform parallel processing from the top to bottom of the stage. It’s a much more efficient way to build core stages. This new capability will streamline final production efforts, allowing our team to have 360-degree access to the stage, both internally and externally.”
The fully assembled core stage for Artemis II arrived July 23, 2024, at Kennedy, where it remained horizontal inside the VAB transfer aisle until its recent lift into the newly outfitted high bay.
Teams at NASA Michoud are outfitting the remaining core stage elements for Artemis III and preparing to horizontally join them. The four RS-25 engines for the Artemis III mission are complete at NASA’s Stennis Space Center in Bay St. Louis, Mississippi, and will be transported to NASA Kennedy in 2025. Major core stage and exploration upper stage structures are in work at NASA Michoud for Artemis IV and beyond.
NASA is working to land the first woman, first person of color, and its first international partner astronaut on the Moon under Artemis. SLS is part of NASA’s backbone for deep space exploration, along with the Orion spacecraft, supporting ground systems, advanced spacesuits and rovers, the Gateway in orbit around the Moon, and commercial human landing systems. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single launch.
News Media Contact
Jonathan Deal
Marshall Space Flight Center
Huntsville, Ala.
256-544-0034
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Data from the SWOT satellite was used to calculate average water levels for lakes and reservoirs in the Ohio River Basin from July 2023 to November 2024. Yellow indicates values greater than 1,600 feet (500 meters) above sea level; dark purple represents water levels less than 330 feet (100 meters). Data from the U.S.-European Surface Water and Ocean Topography mission gives researchers a detailed look at lakes and reservoirs in a U.S. watershed.
The Ohio River Basin stretches from Pennsylvania to Illinois and contains a system of reservoirs, lakes, and rivers that drains an area almost as large as France. Researchers with the SWOT (Surface Water and Ocean Topography) mission, a collaboration between NASA and the French space agency CNES (Centre National d’Études Spatiales), now have a new tool for measuring water levels not only in this area, which is home to more than 25 million people, but in other watersheds around the world as well.
Since early 2023, SWOT has been measuring the height of nearly all water on Earth’s surface — including oceans, lakes, reservoirs, and rivers — covering nearly the entire globe at least once every 21 days. The SWOT satellite also measures the horizontal extent of water in freshwater bodies. Earlier this year, the mission started making validated data publicly available.
“Having these two perspectives — water extent and levels — at the same time, along with detailed, frequent coverage over large areas, is unprecedented,” said Jida Wang, a hydrologist at the University of Illinois Urbana-Champaign and a member of the SWOT science team. “This is a groundbreaking, exciting aspect of SWOT.”
Researchers can use the mission’s data on water level and extent to calculate how the amount of water stored in a lake or reservoir changes over time. This, in turn, can give hydrologists a more precise picture of river discharge — how much water moves through a particular stretch of river.
The visualization above uses SWOT data from July 2023 to November 2024 to show the average water level above sea level in lakes and reservoirs in the Ohio River Basin, which drains into the Mississippi River. Yellow indicates values greater than 1,600 feet (500 meters), and dark purple represents water levels less than 330 feet (100 meters). Comparing how such levels change can help hydrologists measure water availability over time in a local area or across a watershed.
Complementing a Patchwork of Data
Historically, estimating freshwater availability for communities within a river basin has been challenging. Researchers gather information from gauges installed at certain lakes and reservoirs, from airborne surveys, and from other satellites that look at either water level or extent. But for ground-based and airborne instruments, the coverage can be limited in space and time. Hydrologists can piece together some of what they need from different satellites, but the data may or may not have been taken at the same time, or the researchers might still need to augment the information with measurements from ground-based sensors.
Even then, calculating freshwater availability can be complicated. Much of the work relies on computer models. “Traditional water models often don’t work very well in highly regulated basins like the Ohio because they have trouble representing the unpredictable behavior of dam operations,” said George Allen, a freshwater researcher at Virginia Tech in Blacksburg and a member of the SWOT science team.
Many river basins in the United States include dams and reservoirs managed by a patchwork of entities. While the people who manage a reservoir may know how their section of water behaves, planning for water availability down the entire length of a river can be a challenge. Since SWOT looks at both rivers and lakes, its data can help provide a more unified view.
“The data lets water managers really know what other people in these freshwater systems are doing,” said SWOT science team member Colin Gleason, a hydrologist at the University of Massachusetts Amherst.
While SWOT researchers are excited about the possibilities that the data is opening up, there is still much to be done. The satellite’s high-resolution view of water levels and extent means there is a vast ocean of data that researchers must wade through, and it will take some time to process and analyze the measurements.
More About SWOT
The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA’s Jet Propulsion Laboratory, managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES. The KaRIn high-power transmitter assembly was provided by CSA.
To learn more about SWOT, visit:
https://swot.jpl.nasa.gov
News Media Contacts
Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov
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Last Updated Dec 17, 2024 Related Terms
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By NASA
X-rays are radiated by matter hotter than one million Kelvin, and high-resolution X-ray spectroscopy can tell us about the composition of the matter and how fast and in what direction it is moving. Quantum calorimeters are opening this new window on the Universe. First promised four decades ago, the quantum-calorimeter era of X-ray astronomy has finally dawned.
Photo of the XRISM/Resolve quantum-calorimeter array in its storage container prior to integration into the instrument. The 6×6 array, 5 mm on a side, consists of independent detectors – each one a thermally isolated silicon thermistor with a HgTe absorber. The spectrometer consisting of this detector and other essential technologies separates astrophysical X-ray spectra into about 2400 resolution elements, which can be thought of as X-ray colors.NASA GSFC A quantum calorimeter is a device that makes precise measurements of energy quanta by measuring the temperature change that occurs when a quantum of energy is deposited in an absorber with low heat capacity. The absorber is attached to a thermometer that is somewhat decoupled from a heat sink so that the sensor can heat up and then cool back down again. To reduce thermodynamic noise and the heat capacity of the sensor, operation at temperatures less than 0.1 K is required.
The idea for thermal measurement of small amounts of energy occurred in several places in the world independently when scientists observed pulses in the readout of low-temperature thermometers and infrared detectors. They attributed these spurious signals to passing cosmic-ray particles, and considered optimizing detectors for sensitive measurement of the energy of particles and photons.
The idea to develop such sensors for X-ray astronomy was conceived at Goddard Space Flight Center in 1982 when X-ray astronomers were considering instruments to propose for NASA’s planned Advanced X-ray Astrophysics Facility (AXAF). In a fateful conversation, infrared astronomer Harvey Moseley suggested thermal detection could offer substantial improvement over existing solid-state detectors. Using Goddard internal research and development funding, development advanced sufficiently to justify, just two years later, proposing a quantum-calorimeter X-ray Spectrometer (XRS) for inclusion on AXAF. Despite its technical immaturity at the time, the revolutionary potential of the XRS was acknowledged, and the proposal was accepted.
The AXAF design evolved over the subsequent years, however, and the XRS was eliminated from its complement of instruments. After discussions between NASA and the Japanese Institute of Space and Astronautical Science (ISAS), a new XRS was included in the instrument suite of the Japanese Astro-E X-ray observatory. Astro-E launched in 2000 but did not reach orbit due to an anomaly in the first stage of the rocket. Astro-E2, a rebuild of Astro-E, was successfully placed in orbit in 2005 and renamed Suzaku, but the XRS instrument ceased operation before observations started due to loss of the liquid helium, an essential part of the detector cooling system, caused by a faulty storage system.
A redesigned mission, Astro-H, that included a quantum-calorimeter instrument with a redundant cooling system was successfully launched in 2016 and renamed Hitomi. Hitomi’s Soft X-ray Spectrometer (SXS) obtained high resolution spectra of the Perseus cluster of galaxies and a few other sources before a problem with the attitude control system caused the mission to be lost roughly one month after launch. Even so, Hitomi was the first orbiting observatory to obtain a scientific result using X-ray quantum calorimeters. The spectacular Perseus spectrum generated by the SXS motivated yet another attempt to implement a spaceborne quantum-calorimeter spectrometer.
The X-ray Imaging and Spectroscopy Mission (XRISM) was launched in September 2023, with the spectrometer aboard renamed Resolve to represent not only its function but also the resolve of the U.S./Japan collaboration to study the Universe through the window of this new capability. XRISM has been operating well in orbit for over a year.
Development of the Sensor Technology
Development of the sensor technology employed in Resolve began four decades ago. Note that an X-ray quantum-calorimeter spectrometer requires more than the sensor technology. Other technologies, such as the coolers that provide a
The sensors used from XRS through Resolve were all based on silicon-thermistor thermometers and mercury telluride (HgTe) X-ray absorbers. They used arrays consisting of 32 to 36 pixels, each of which was an independent quantum calorimeter. Between Astro-E and Astro-E2, a new method of making the thermistor was developed that significantly reduced its low-frequency noise. Other fabrication advances made it possible to make reproducible connections between absorbers and thermistors and to fit each thermistor and its thermal isolation under its X-ray absorber, making square arrays feasible.
Through a Small Business Innovation Research (SBIR) contract executed after the Astro-E2 mission, EPIR Technologies Inc. reduced the specific heat of the HgTe absorbers. Additional improvements made to the cooler of the detector heat sink allowed operation at a lower temperature, which further reduced the specific heat. Together, these changes enabled the pixel width to be increased from 0.64 mm to 0.83 mm while still achieving a lower heat capacity, and thus improving the energy resolution. From Astro-E through Astro-H, the energy resolution for X-rays of energy around 6000 eV improved from 11 eV, to 5.5 eV, to 4 eV. No changes to the array design were made between Astro-H and XRISM.
Resolve detector scientist Caroline Kilbourne installing the flight Resolve quantum-calorimeter array into the assembly that provides its electrical, thermal, and mechanical interfaces.NASA GSFC Over the same period, other approaches to quantum-calorimeter arrays optimized for the needs of future missions were developed. The use of superconducting transition-edge sensors (TES) instead of silicon (Si) thermistors led to improved energy resolution, more pixels per array, and multiplexing (a technique that allows multiple signals to be carried on a single wire). Quantum-calorimeter arrays with thousands of pixels are now standard, such as in the NASA contribution to the future European New Advanced Telescope for High-ENergy Astrophysics (newAthena) mission. And quantum calorimeters using paramagnetic thermometers — which unlike TES and Si thermistors require no dissipation of heat in the thermometer for it to be read out — combined with high-density wiring are a promising route for realizing even larger arrays. (See Astrophysics Technology Highlight on these latest developments.)
The Resolve instrument aboard XRISM (X-ray Imaging and Spectroscopy Mission) captured data from the center of galaxy NGC 4151, where a supermassive black hole is slowly consuming material from the surrounding accretion disk. The resulting spectrum reveals the presence of iron in the peak around 6.5 keV and the dips around 7 keV, light thousands of times more energetic that what our eyes can see. Background: An image of NGC 4151 constructed from a combination of X-ray, optical, and radio light.Spectrum: JAXA/NASA/XRISM Resolve. Background: X-rays, NASA/CXC/CfA/J.Wang et al.; optical, Isaac Newton Group of Telescopes, La Palma/Jacobus Kapteyn Telescope; radio, NSF/NRAO/VLA Results from Resolve
So, what is Resolve revealing about the Universe? Through spectroscopy alone, Resolve allows us to construct images of complex environments where collections of gas and dust with various attributes exist, emitting and absorbing X-rays at energies characteristic of their various compositions, velocities, and temperatures. For example, in the middle of the galaxy known as NCG 4151 (see figure above), matter spiraling into the central massive black hole forms a circular structure that is flat near the black hole, more donut-shaped further out, and, according to the Resolve data, a bit lumpy. Matter near the black hole is heated up to X-ray-emitting temperatures and irradiates the matter in the circular structure. The Resolve spectrum has a bright narrow emission line (peak) from neutral iron atoms that must be coming from colder matter in the circular structure, because hotter material would be ionized, and would have a different emission signature. Nonetheless, the shape of the iron line needs three components to describe it, each coming from a different lump in the circular structure. The presence of absorption lines (dips) in the spectrum provides further detail about the structure of the infalling matter.
A second example is the detection of X-ray emission by Resolve from the debris of stars that have exploded, such as N132D (see figure below), that will improve our understanding of the explosion mechanism and how the elements produced in stars get distributed, and allow us to infer the type of star each was before ending in a supernova. Elements are identified by their characteristic emission lines, and shifts of those lines via the Doppler effect tell us how fast the material is moving.
XRISM’s Resolve instrument captured data from supernova remnant N132D in the Large Magellanic Cloud to create the most detailed X-ray spectrum of the object ever made. The spectrum reveals peaks associated with silicon, sulfur, argon, calcium, and iron. Inset at right is an image of N132D captured by XRISM’s Xtend instrument.JAXA/NASA/XRISM Resolve and Xtend These results are just the beginning. The rich Resolve data sets are identifying complex velocity structures, rare elements, and multiple temperature components in a diverse ensemble of cosmic objects. Welcome to the quantum calorimeter era! Stay tuned for more revelations!
Project Leads: Dr. Caroline Kilbourne, NASA Goddard Space Flight Center (GSFC), for silicon-thermistor quantum calorimeter development from Astro-E2 through XRISM and early TES development. Foundational and other essential leadership provided by Dr. Harvey Moseley, Dr. John Mather, Dr. Richard Kelley, Dr. Andrew Szymkowiak, Mr. Brent Mott, Dr. F. Scott Porter, Ms. Christine Jhabvala, Dr. James Chervenak (GSFC at the time of the work) and Dr. Dan McCammon (U. Wisconsin).
Sponsoring Organizations and Programs: The NASA Headquarters Astrophysics Division sponsored the projects, missions, and other efforts that culminated in the development of the Resolve instrument.
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