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Mars Express celebrates 25 000 orbits
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By NASA
NASA/JPL-Caltech/University of Arizona This Oct. 29, 2018, image from the HiRISE camera on NASA’s Mars Reconnaissance Orbiter captures geysers of gas and dust that occur in springtime in the South Polar region of Mars. As the Sun rises higher in the sky, the thick coating of carbon dioxide ice that accumulated over the winter begins to warm and then turn to vapor. Sunlight penetrates through the transparent ice and is absorbed at the base of the ice layer. The gas that forms because of the warming escapes through weaknesses in the ice and erupts in the form of geysers.
HiRISE, or the High Resolution Imaging Science Experiment, is a powerful camera that takes pictures covering vast areas of Martian terrain while being able to see features as small as a kitchen table.
Image credit: NASA/JPL-Caltech/University of Arizona
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By NASA
4 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A test rover with shape memory alloy spring tires traverses rocky, Martian-simulated terrain.Credit: NASA The mystique of Mars has been studied for centuries. The fourth planet from the Sun is reminiscent of a rich, red desert and features a rugged surface challenging to traverse. While several robotic missions have landed on Mars, NASA has only explored 1% of its surface. Ahead of future human and robotic missions to the Red Planet, NASA recently completed rigorous rover testing on Martian-simulated terrain, featuring revolutionary shape memory alloy spring tire technology developed at the agency’s Glenn Research Center in Cleveland in partnership with Goodyear Tire & Rubber.
Rovers — mobile robots that explore lunar or planetary surfaces — must be equipped with adequate tires for the environments they’re exploring. As Mars has an uneven, rocky surface, durable tires are essential for mobility. Shape memory alloy (SMA) spring tires help make that possible.
Shape memory alloys are metals that can return to their original shape after being bent, stretched, heated, and cooled. NASA has used them for decades, but applying this technology to tires is a fairly new concept.
“We at Glenn are one of the world leaders in bringing the science and understanding of how you change the alloy compositions, how you change the processing of the material, and how you model these systems in a way that we can control and stabilize the behaviors so that they can actually be utilized in real applications,” said Dr. Santo Padula II, materials research engineer at NASA Glenn.
Researchers from NASA’s Glenn Research Center and Airbus Defence & Space pose with a test rover on Martian-simulated terrain.Credit: NASA Padula and his team have tested several applications for SMAs, but his epiphany of the possibilities for tires came about because of a chance encounter.
While leaving a meeting, Padula encountered Colin Creager, a mechanical engineer at NASA Glenn whom he hadn’t seen in years. Creager used the opportunity to tell him about the work he was doing in the NASA Glenn Simulated Lunar Operations (SLOPE) Laboratory, which can simulate the surfaces of the Moon and Mars to help scientists test rover performance. He brought Padula to the lab, where Padula immediately took note of the spring tires. At the time, they were made of steel.
Padula remarked, “The minute I saw the tire, I said, aren’t you having problems with those plasticizing?” Plasticizing refers to a metal undergoing deformation that isn’t reversible and can lead to damage or failure of the component.
“Colin told me, ‘That’s the only problem we can’t solve.’” Padula continued, “I said, I have your solution. I’m developing a new alloy that will solve that. And that’s how SMA tires started.”
From there, Padula, Creager, and their teams joined forces to improve NASA’s existing spring tires with a game-changing material: nickel-titanium SMAs. The metal can accommodate deformation despite extreme stress, permitting the tires to return to their original shape even with rigorous impact, which is not possible for spring tires made with conventional metal.
Credit: NASA Since then, research has been abundant, and in the fall of 2024, teams from NASA Glenn traveled to Airbus Defence and Space in Stevenage, United Kingdom, to test NASA’s innovative SMA spring tires. Testing took place at the Airbus Mars Yard — an enclosed facility created to simulate the harsh conditions of Martian terrain.
“We went out there with the team, we brought our motion tracking system and did different tests uphill and back downhill,” Creager said. “We conducted a lot of cross slope tests over rocks and sand where the focus was on understanding stability because this was something we had never tested before.”
During the tests, researchers monitored rovers as the wheels went over rocks, paying close attention to how much the crowns of the tires shifted, any damage, and downhill sliding. The team expected sliding and shifting, but it was very minimal, and testing met all expectations. Researchers also gathered insights about the tires’ stability, maneuverability, and rock traversal capabilities.
As NASA continues to advance systems for deep space exploration, the agency’s Extravehicular Activity and Human Surface Mobility program enlisted Padula to research additional ways to improve the properties of SMAs for future rover tires and other potential uses, including lunar environments.
“My goal is to extend the operating temperature capability of SMAs for applications like tires, and to look at applying these materials for habitat protection,” Padula said. “We need new materials for extreme environments that can provide energy absorption for micrometeorite strikes that happen on the Moon to enable things like habitat structures for large numbers of astronauts and scientists to do work on the Moon and Mars.”
Researchers say shape memory alloy spring tires are just the beginning.
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By NASA
Hubble Space TelescopeHubble Home OverviewAbout Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & BenefitsHubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts ScienceHubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky ObservatoryHubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb TeamHubble Team Career Aspirations Hubble Astronauts NewsHubble News Hubble News Archive Social Media Media Resources MultimediaMultimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More35th Anniversary 7 Min Read NASA Celebrates Edwin Hubble’s Discovery of a New Universe
The Cepheid variable star, called V1, in the neighboring Andromeda galaxy. Credits: NASA, ESA, Hubble Heritage Team (STScI/AURA); Acknowledgement: R. Gendler For humans, the most important star in the universe is our Sun. The second-most important star is nestled inside the Andromeda galaxy. Don’t go looking for it — the flickering star is 2.2 million light-years away, and is 1/100,000th the brightness of the faintest star visible to the human eye.
Yet, a century ago, its discovery by Edwin Hubble, then an astronomer at Carnegie Observatories, opened humanity’s eyes as to how large the universe really is, and revealed that our Milky Way galaxy is just one of hundreds of billions of galaxies in the universe ushered in the coming-of-age for humans as a curious species that could scientifically ponder our own creation through the message of starlight. Carnegie Science and NASA are celebrating this centennial at the 245th meeting of the American Astronomical Society in Washington, D.C.
The seemingly inauspicious star, simply named V1, flung open a Pandora’s box full of mysteries about time and space that are still challenging astronomers today. Using the largest telescope in the world at that time, the Carnegie-funded 100-inch Hooker Telescope at Mount Wilson Observatory in California, Hubble discovered the demure star in 1923. This rare type of pulsating star, called a Cepheid variable, is used as milepost markers for distant celestial objects. There are no tape-measures in space, but by the early 20th century Henrietta Swan Leavitt had discovered that the pulsation period of Cepheid variables is directly tied to their luminosity.
Many astronomers long believed that the edge of the Milky Way marked the edge of the entire universe. But Hubble determined that V1, located inside the Andromeda “nebula,” was at a distance that far exceeded anything in our own Milky Way galaxy. This led Hubble to the jaw-dropping realization that the universe extends far beyond our own galaxy.
In fact Hubble had suspected there was a larger universe out there, but here was the proof in the pudding. He was so amazed he scribbled an exclamation mark on the photographic plate of Andromeda that pinpointed the variable star.
In commemoration of Edwin Hubble’s discovery of a Cepheid variable class star, called V1, in the neighboring Andromeda galaxy 100 years ago, astronomers partnered with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, producing a plot, or light curve, of the rhythmic rise and fall of the star’s light. Based on this data, the Hubble Space Telescope was scheduled to capture the star at its dimmest and brightest light. Edwin Hubble’s observations of V1 became the critical first step in uncovering a larger, grander universe than some astronomers imagined at the time. Once dismissed as a nearby “spiral nebula” measurements of Andromeda with its embedded Cepheid star served as a stellar milepost marker. It definitively showed that Andromeda was far outside of our Milky Way. Edwin Hubble went on to measure the distances to many galaxies beyond the Milky Way by finding Cepheid variables within those levels. The velocities of those galaxies, in turn, allowed him to determine that the universe is expanding.NASA, ESA, Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Gendler As a result, the science of cosmology exploded almost overnight. Hubble’s contemporary, the distinguished Harvard astronomer Harlow Shapley, upon Hubble notifying him of the discovery, was devastated. “Here is the letter that destroyed my universe,” he lamented to fellow astronomer Cecilia Payne-Gaposchkin, who was in his office when he opened Hubble’s message.
Just three years earlier, Shapley had presented his observational interpretation of a much smaller universe in a debate one evening at the Smithsonian Museum of Natural History in Washington. He maintained that the Milky Way galaxy was so huge, it must encompass the entirety of the universe. Shapley insisted that the mysteriously fuzzy “spiral nebulae,” such as Andromeda, were simply stars forming on the periphery of our Milky Way, and inconsequential.
Little could Hubble have imagined that 70 years later, an extraordinary telescope named after him, lofted hundreds of miles above the Earth, would continue his legacy. The marvelous telescope made “Hubble” a household word, synonymous with wonderous astronomy.
Today, NASA’s Hubble Space Telescope pushes the frontiers of knowledge over 10 times farther than Edwin Hubble could ever see. The space telescope has lifted the curtain on a compulsive universe full of active stars, colliding galaxies, and runaway black holes, among the celestial fireworks of the interplay between matter and energy.
Edwin Hubble was the first astronomer to take the initial steps that would ultimately lead to the Hubble Space Telescope, revealing a seemingly infinite ocean of galaxies. He thought that, despite their abundance, galaxies came in just a few specific shapes: pinwheel spirals, football-shaped ellipticals, and oddball irregular galaxies. He thought these might be clues to galaxy evolution – but the answer had to wait for the Hubble Space Telescope’s legendary Hubble Deep Field in 1994.
The most impactful finding that Edwin Hubble’s analysis showed was that the farther the galaxy is, the faster it appears to be receding from Earth. The universe looked like it was expanding like a balloon. This was based on Hubble tying galaxy distances to the reddening of light — the redshift – that proportionally increased the father away the galaxies are.
The redshift data were first collected by Lowell Observatory astronomer Vesto Slipher, who spectroscopically studied the “spiral nebulae” a decade before Hubble. Slipher did not know they were extragalactic, but Hubble made the connection. Slipher first interpreted his redshift data an example of the Doppler effect. This phenomenon is caused by light being stretched to longer, redder wavelengths if a source is moving away from us. To Slipher, it was curious that all the spiral nebulae appeared to be moving away from Earth.
Two years prior to Hubble publishing his findings, the Belgian physicist and Jesuit priest Georges Lemaître analyzed the Hubble and Slifer observations and first came to the conclusion of an expanding universe. This proportionality between galaxies’ distances and redshifts is today termed Hubble–Lemaître’s law.
Because the universe appeared to be uniformly expanding, Lemaître further realized that the expansion rate could be run back into time – like rewinding a movie – until the universe was unimaginably small, hot, and dense. It wasn’t until 1949 that the term “big bang” came into fashion.
This was a relief to Edwin Hubble’s contemporary, Albert Einstein, who deduced the universe could not remain stationary without imploding under gravity’s pull. The rate of cosmic expansion is now known as the Hubble Constant.
Ironically, Hubble himself never fully accepted the runaway universe as an interpretation of the redshift data. He suspected that some unknown physics phenomenon was giving the illusion that the galaxies were flying away from each other. He was partly right in that Einstein’s theory of special relativity explained redshift as an effect of time-dilation that is proportional to the stretching of expanding space. The galaxies only appear to be zooming through the universe. Space is expanding instead.
Compass and scale image titled “Cepheid Variable Star V1 in M31 HST WFC3/UVIS.” Four boxes each showing a bright white star in the center surrounded by other stars. Each box has a correlating date at the bottom: Dec. 17, 2020, Dec. 21, 2010, Dec. 30, 2019, and Jan. 26, 2011. The center star in the boxes appears brighter with each passing date.NASA, ESA, Hubble Heritage Project (STScI, AURA) After decades of precise measurements, the Hubble telescope came along to nail down the expansion rate precisely, giving the universe an age of 13.8 billion years. This required establishing the first rung of what astronomers call the “cosmic distance ladder” needed to build a yardstick to far-flung galaxies. They are cousins to V1, Cepheid variable stars that the Hubble telescope can detect out to over 100 times farther from Earth than the star Edwin Hubble first found.
Astrophysics was turned on its head again in 1998 when the Hubble telescope and other observatories discovered that the universe was expanding at an ever-faster rate, through a phenomenon dubbed “dark energy.” Einstein first toyed with this idea of a repulsive form of gravity in space, calling it the cosmological constant.
Even more mysteriously, the current expansion rate appears to be different than what modern cosmological models of the developing universe would predict, further confounding theoreticians. Today astronomers are wrestling with the idea that whatever is accelerating the universe may be changing over time. NASA’s Roman Space Telescope, with the ability to do large cosmic surveys, should lead to new insights into the behavior of dark matter and dark energy. Roman will likely measure the Hubble constant via lensed supernovae.
This grand century-long adventure, plumbing depths of the unknown, began with Hubble photographing a large smudge of light, the Andromeda galaxy, at the Mount Wilson Observatory high above Los Angeles.
In short, Edwin Hubble is the man who wiped away the ancient universe and discovered a new universe that would shrink humanity’s self-perception into being an insignificant speck in the cosmos.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Edwin Hubble Hubble Views the Star That Changed the Universe The History of Hubble Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Ray Villard
Space Telescope Science Institute, Baltimore, MD
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Last Updated Jan 15, 2025 EditorAndrea GianopoulosLocationNASA Goddard Space Flight Center Related Terms
Andromeda Galaxy Astrophysics Astrophysics Division Goddard Space Flight Center Hubble Space Telescope Stars The Universe Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Discovering a Runaway Universe
Our cosmos is growing, and that expansion rate is accelerating.
The History of Hubble
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of the Thermo-Photo-Catalysis of Water for Crewed Mars Transit Spacecraft Oxygen Supply concept.NASA/Saurabh Vilekar Saurabh Vilekar
Precision Combustion
Precision Combustion, Inc. (PCI) proposes to develop a uniquely compact, lightweight, low-power, and durable Microlith® Thermo-Photo-Catalytic (TPC) Reactor for crewed Mars transit spacecraft O2 supply. As crewed space exploration mission destinations move from low Earth orbit to sustained lunar surface habitation toward Mars exploration, the need becomes more intense to supplant heritage physico-chemical unit operations employed for crewed spacecraft cabin CO2 removal, CO2 reduction, and O2 supply. The primary approach to date has been toward incremental improvement of the heritage, energy intensive process technologies used aboard the International Space Station (ISS), particularly for water electrolysis-based O2 generation. A major breakthrough is necessary to depose these energy intensive process technologies either partly or completely. This is achievable by considering the recent advances in photocatalysis. Applications are emerging for converting CO2 to useful commodity products and generating H2 from atmospheric water vapor. Considering these developments, a low power thermo-photo-catalytic process to replace the heritage high-power water electrolysis process is proposed for application to a Mars transit vehicle life support system (LSS) functional architecture. A key component in realizing this breakthrough is utilizing a catalyst substrate such as Microlith that affords high surface area and promotes mass transport to the catalyst surface. The proposed TPC oxygenator is expected to operate passively to continually renew the O2 content of the cabin atmosphere. The targeted mission for the proposed TPC oxygenator technology deployment is a 2039 Long Stay, Earth-Mars-Earth mission opportunity. This mission as defined by the Moon to Mars (M2M) 2024 review consists of 337.9 days outbound, 348.5 days in Mars vicinity, and 295.8 days return for a total 982.2-day mission. The proposed Microlith oxygenator technology, if successful, is envisioned to replace the OGA technology in the LSS process architecture with significant weight and power savings. In Phase I, we will demonstrate technical feasibility of Microlith TPC for O2 generation, interface requirements, and integration trade space and a clear path towards a prototype demonstration in Phase II will also be described in the final report.
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Last Updated Jan 10, 2025 EditorLoura Hall Related Terms
NIAC Studies NASA Innovative Advanced Concepts (NIAC) Program Keep Exploring Discover More NIAC Topics
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By NASA
Modular Assembled Radiators for Nuclear Electric Propulsion Vehicles, or MARVL, aims to take a critical element of nuclear electric propulsion, its heat dissipation system, and divide it into smaller components that can be assembled robotically and autonomously in space. This is an artist’s rendering of what the fully assembled system might look like.NASA The trip to Mars and back is not one for the faint of heart. We’re not talking days, weeks, or months. But there are technologies that could help transport a crew on that round-trip journey in a relatively quick two years.
One option NASA is exploring is nuclear electric propulsion, which employs a nuclear reactor to generate electricity that ionizes, or positively charges, and electrically accelerates gaseous propellants to provide thrust to a spacecraft.
Researchers at NASA’s Langley Research Center in Hampton, Virginia, are working on a system that could help bring nuclear electric propulsion one significant, technology-defining step closer to reality.
Modular Assembled Radiators for Nuclear Electric Propulsion Vehicles, or MARVL, aims to take a critical element of nuclear electric propulsion, its heat dissipation system, and divide it into smaller components that can be assembled robotically and autonomously in space.
“By doing that, we eliminate trying to fit the whole system into one rocket fairing,” said Amanda Stark, a heat transfer engineer at NASA Langley and the principal investigator for MARVL. “In turn, that allows us to loosen up the design a little bit and really optimize it.”
Loosening up the design is key, because as Stark mentioned, previous ideas called for fitting the entire nuclear electric radiator system under a rocket fairing, or nose cone, which covers and protects a payload. Fully deployed, the heat dissipating radiator array would be roughly the size of a football field. You can imagine the challenge engineers would face in getting such a massive system folded up neatly inside the tip of a rocket.
The MARVL technology opens a world of possibilities. Rather than cram the whole system into an existing rocket, this would allow researchers the flexibility to send pieces of the system to space in whatever way would make the most sense, then have it all assembled off the planet.
Once in space, robots would connect the nuclear electric propulsion system’s radiator panels, through which a liquid metal coolant, such as a sodium-potassium alloy, would flow.
While this is still an engineering challenge, it is exactly the kind of engineering challenge in-space-assembly experts at NASA Langley have been working on for decades. The MARVL technology could mark a significant first milestone. Rather than being an add-on to an existing technology, the in-space assembly component will benefit and influence the design of the very spacecraft it would serve.
“Existing vehicles have not previously considered in-space assembly during the design process, so we have the opportunity here to say, ‘We’re going to build this vehicle in space. How do we do it? And what does the vehicle look like if we do that?’ I think it’s going to expand what we think of when it comes to nuclear propulsion,” said Julia Cline, a mentor for the project in NASA Langley’s Research Directorate, who led the center’s participation in the Nuclear Electric Propulsion tech maturation plan development as a precursor to MARVL. That tech maturation plan was run out of the agency’s Space Nuclear Propulsion project at Marshall Space Flight Center in Huntsville, Alabama.
NASA’s Space Technology Mission Directorate awarded the MARVL project through the Early Career Initiative, giving the team two years to advance the concept. Stark and her teammates are working with an external partner, Boyd Lancaster, Inc., to develop the thermal management system. The team also includes radiator design engineers from NASA’s Glenn Research Center in Cleveland and fluid engineers from NASA’s Kennedy Space Center in Florida. After two years, the team hopes to move the MARVL design to a small-scale ground demonstration.
The idea of robotically building a nuclear propulsion system in space is sparking imaginations.
“One of our mentors remarked, ‘This is why I wanted to work at NASA, for projects like this,’” said Stark, “which is awesome because I am so happy to be involved with it, and I feel the same way.”
Additional support for MARVL comes from the agency’s Space Nuclear Propulsion project. The project’s ongoing effort is maturing technologies for operations around the Moon and near-Earth exploration, deep space science missions, and human exploration using nuclear electric propulsion and nuclear thermal propulsion.
An artist’s rendering that shows the different components of a fully assembled nuclear electric propulsion system.NASAView the full article
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