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Views Of The Moon - Lunar Images Taken From Orbit by Nasa Lunar Reconnaissance Orbiter (LRO)
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Hubble Space Telescope Home NASA’s Hubble Finds… Hubble Space Telescope Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts E-books Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More Online Activities 5 Min Read NASA’s Hubble Finds Sizzling Details About Young Star FU Orionis
An artist’s concept of the early stages of the young star FU Orionis (FU Ori) outburst, surrounded by a disk of material. Credits:
NASA-JPL, Caltech In 1936, astronomers saw a puzzling event in the constellation Orion: the young star FU Orionis (FU Ori) became a hundred times brighter in a matter of months. At its peak, FU Ori was intrinsically 100 times brighter than our Sun. Unlike an exploding star though, it has declined in luminosity only languidly since then.
Now, a team of astronomers has wielded NASA’s Hubble Space Telescope‘s ultraviolet capabilities to learn more about the interaction between FU Ori’s stellar surface and the accretion disk that has been dumping gas onto the growing star for nearly 90 years. They find that the inner disk touching the star is extraordinarily hot — which challenges conventional wisdom.
The observations were made with the telescope’s COS (Cosmic Origins Spectrograph) and STIS (Space Telescope Imaging Spectrograph) instruments. The data includes the first far-ultraviolet and new near-ultraviolet spectra of FU Ori.
“We were hoping to validate the hottest part of the accretion disk model, to determine its maximum temperature, by measuring closer to the inner edge of the accretion disk than ever before,” said Lynne Hillenbrand of Caltech in Pasadena, California, and a co-author of the paper. “I think there was some hope that we would see something extra, like the interface between the star and its disk, but we were certainly not expecting it. The fact we saw so much extra — it was much brighter in the ultraviolet than we predicted — that was the big surprise.”
A Better Understanding of Stellar Accretion
Originally deemed to be a unique case among stars, FU Ori exemplifies a class of young, eruptive stars that undergo dramatic changes in brightness. These objects are a subset of classical T Tauri stars, which are newly forming stars that are building up by accreting material from their disk and the surrounding nebula. In classical T Tauri stars, the disk does not touch the star directly because it is restricted by the outward pressure of the star’s magnetic field.
The accretion disks around FU Ori objects, however, are susceptible to instabilities due to their enormous mass relative to the central star, interactions with a binary companion, or infalling material. Such instability means the mass accretion rate can change dramatically. The increased pace disrupts the delicate balance between the stellar magnetic field and the inner edge of the disk, leading to material moving closer in and eventually touching the star’s surface.
This is an artist’s concept of the early stages of the young star FU Orionis (FU Ori) outburst, surrounded by a disk of material. A team of astronomers has used the Hubble Space Telescope’s ultraviolet capabilities to learn more about the interaction between FU Ori’s stellar surface and the accretion disk that has been dumping gas onto the growing star for nearly 90 years. They found that the inner disk, touching the star, is much hotter than expected—16,000 kelvins—nearly three times our Sun’s surface temperature. That sizzling temperature is nearly twice as hot as previously believed. NASA-JPL, Caltech
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The enhanced infall rate and proximity of the accretion disk to the star make FU Ori objects much brighter than a typical T Tauri star. In fact, during an outburst, the star itself is outshined by the disk. Furthermore, the disk material is orbiting rapidly as it approaches the star, much faster than the rotation rate of the stellar surface. This means that there should be a region where the disk impacts the star and the material slows down and heats up significantly.
“The Hubble data indicates a much hotter impact region than models have previously predicted,” said Adolfo Carvalho of Caltech and lead author of the study. “In FU Ori, the temperature is 16,000 kelvins [nearly three times our Sun’s surface temperature]. That sizzling temperature is almost twice the amount prior models have calculated. It challenges and encourages us to think of how such a jump in temperature can be explained.”
To address the significant difference in temperature between past models and the recent Hubble observations, the team offers a revised interpretation of the geometry within FU Ori’s inner region: The accretion disk’s material approaches the star and once it reaches the stellar surface, a hot shock is produced, which emits a lot of ultraviolet light.
Planet Survival Around FU Ori
Understanding the mechanisms of FU Ori’s rapid accretion process relates more broadly to ideas of planet formation and survival.
“Our revised model based on the Hubble data is not strictly bad news for planet evolution, it’s sort of a mixed bag,” explained Carvalho. “If the planet is far out in the disk as it’s forming, outbursts from an FU Ori object should influence what kind of chemicals the planet will ultimately inherit. But if a forming planet is very close to the star, then it’s a slightly different story. Within a couple outbursts, any planets that are forming very close to the star can rapidly move inward and eventually merge with it. You could lose, or at least completely fry, rocky planets forming close to such a star.”
Additional work with the Hubble UV observations is in progress. The team is carefully analyzing the various spectral emission lines from multiple elements present in the COS spectrum. This should provide further clues on FU Ori’s environment, such as the kinematics of inflowing and outflowing gas within the inner region.
“A lot of these young stars are spectroscopically very rich at far ultraviolet wavelengths,” reflected Hillenbrand. “A combination of Hubble, its size and wavelength coverage, as well as FU Ori’s fortunate circumstances, let us see further down into the engine of this fascinating star-type than ever before.”
These findings have been published in The Astrophysical Journal Letters.
The observations were taken as part of General Observer program 17176.
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.
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contacts:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Abigail Major, Ray Villard
Space Telescope Science Institute, Baltimore, MD
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Last Updated Nov 21, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
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Internal defects are always formed in laser welding process due to the keyhole instability, molten pool collapse, and rapid solidification. The extreme lunar environment complicates the reliable implementation of welding, thereby enhancing the welding defects formation. The welding defects are critical material barriers preventing the metal components from Moon exploration. Professor Wei Li’s team will establish an integrated computational materials modelling framework to study the process-structure-property linkage of laser welding under the lunar conditions. The research is emphasized on modelling the internal defects (void, lack of fusion) formed in the lunar laser welding by fully considering the reduced gravity, large temperature change, and extreme vacuum on the Moon surface, and predicting the influence of internal defects on the material and mechanical properties of welding joint.
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Lunar dust may seem unimposing, but it presents a significant challenge for space missions. Its abrasive and jagged particles can damage equipment, clog devices, and even pose health risks to astronauts. This project addresses such issues by developing advanced coatings composed of crumpled nano-balls made from atomically thin 2D materials such as MoS₂, graphene, and MXenes. By crumpling these nanosheets—much like crumpling a piece of paper—we create compression and aggregation resistant particles that can be dispersed in sprayable solutions. As a thin film coating, these crumpled nano-balls form corrugated structures that passively reduce dust adhesion and surface wear. The deformable crumpled nano-ball (DCN) coating works by minimizing the contact area between lunar dust and surfaces, thanks to its unique nano-engineered design. The 2D materials exhibit exceptional durability, withstanding extreme thermal and vacuum environments, as well as resisting radiation damage. Additionally, the flexoelectric and electrostatically dissipative properties of MoS₂, graphene, and MXenes allow the coating to neutralize and dissipate electrical charges, making them highly responsive to the charged lunar dust environment. The project will be executed in three phases, each designed to bring the technology closer to real-world space applications. First, we will synthesize the crumpled nano-balls and investigate their adhesion properties using advanced microscopy techniques. The second phase will focus on fundamental testing in simulated lunar environments, where the coating will be exposed to extreme temperatures, vacuum, radiation, and abrasion. Finally, the third phase will involve applying the coating to space-heritage materials and conducting comprehensive testing in a simulated lunar environment, targeting up to 90% dust clearance and verifying durability over repeated cycles of dust exposure. This research aligns with NASA’s goals for safer, more sustainable lunar missions by reducing maintenance requirements and extending equipment lifespan. Moreover, the potential applications extend beyond space exploration, with the technology offering promising advances in terrestrial industries such as aerospace and electronics by providing ultra-durable, wear-resistant surfaces. Ultimately, the project contributes to advancing materials science and paving the way for NASA’s long-term vision of sustainable space exploration.
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
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Lunar dust, with its highly abrasive and electrostatic properties, poses serious threats to the longevity and functionality of spacecraft, habitats, and equipment operating on the Moon. This project aims to develop advanced bioinspired surface textures that effectively repel lunar dust, targeting critical surfaces such as habitat exteriors, doors, and windows. By designing and fabricating innovative micro-/nano-hierarchical core-shell textures, we aim to significantly reduce dust adhesion, ultimately enhancing the performance and durability of lunar infrastructure. Using cutting-edge fabrication methods like two-photon lithography and atomic layer deposition, our team will create resilient, dust-repelling textures inspired by natural surfaces. We will also conduct in-situ testing with a scanning electron microscope to analyze individual particle adhesion and triboelectric effects, gaining critical insights into lunar dust behavior on engineered surfaces. These findings will guide the development of durable surfaces for long-lasting, low-maintenance lunar equipment, with broader applications for other dust-prone environments.
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By NASA
An artist’s concept of SpaceX’s Starship Human Landing System (HLS) on the Moon. NASA is working with SpaceX to develop the Starship HLS to carry astronauts from lunar orbit to the Moon’s surface and back for Artemis III and Artemis IV. Starship HLS is roughly 50 meters tall, or about the length of an Olympic swimming pool. SpaceX This artist’s concept depicts a SpaceX Starship tanker (bottom) transferring propellant to a Starship depot (top) in low Earth orbit. Before astronauts launch in Orion atop the agency’s SLS (Space Launch System) rocket, SpaceX will launch a storage depot to Earth orbit. For the Artemis III and Artemis IV missions, SpaceX plans to complete propellant loading operations in Earth orbit to send a fully fueled Starship Human Landing System (HLS) to the Moon. SpaceX An artist’s concept shows how a crewed Orion spacecraft will dock to SpaceX’s Starship Human Landing System (HLS) in lunar orbit for Artemis III. Starship HLS will dock directly to Orion so that two astronauts can transfer to the lander to descend to the Moon’s surface, while two others remain in Orion. Beginning with Artemis IV, NASA’s Gateway lunar space station will serve as the crew transfer point. SpaceX The artist’s concept shows two Artemis III astronauts preparing to step off the elevator at the bottom of SpaceX’s Starship HLS to the Moon’s surface. At about 164 feet (50 m), Starship HLS will be about the same height as a 15-story building. (SpaceX)The elevator will be used to transport crew and cargo between the lander and the surface. SpaceX NASA is working with U.S. industry to develop the human landing systems that will safely carry astronauts from lunar orbit to the surface of the Moon and back throughout the agency’s Artemis campaign.
For Artemis III, the first crewed return to the lunar surface in over 50 years, NASA is working with SpaceX to develop the company’s Starship Human Landing System (HLS). Newly updated artist’s conceptual renders show how Starship HLS will dock with NASA’s Orion spacecraft in lunar orbit, then two Artemis crew members will transfer from Orion to Starship and descend to the surface. There, astronauts will collect samples, perform science experiments, and observe the Moon’s environment before returning in Starship to Orion waiting in lunar orbit. Prior to the crewed Artemis III mission, SpaceX will perform an uncrewed landing demonstration mission on the Moon.
NASA is also working with SpaceX to further develop the company’s Starship lander to meet an extended set of requirements for Artemis IV. These requirements include landing more mass on the Moon and docking with the agency’s Gateway lunar space station for crew transfer.
The artist’s concept portrays SpaceX’s Starship HLS with two Raptor engines lit performing a braking burn prior to its Moon landing. The burn will occur after Starship HLS departs low lunar orbit to reduce the lander’s velocity prior to final descent to the lunar surface. SpaceX With Artemis, NASA will explore more of the Moon than ever before, learn how to live and work away from home, and prepare for future human exploration of Mars. NASA’s SLS (Space Launch System) rocket, exploration ground systems, and Orion spacecraft, along with the human landing system, next-generation spacesuits, Gateway lunar space station, and future rovers are NASA’s foundation for deep space exploration.
For more on HLS, visit:
https://www.nasa.gov/humans-in-space/human-landing-system
News Media Contact
Corinne Beckinger
Marshall Space Flight Center, Huntsville, Ala.
256.544.0034
corinne.m.beckinger@nasa.gov
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