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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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Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Exploring the Birth of Stars
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Hubble Focus: The Lives of Stars
This e-book highlights the mission’s recent discoveries and observations related to the birth, evolution, and death of stars.
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By NASA
Curiosity Navigation Curiosity Home Mission Overview Where is Curiosity? Mission Updates Science Overview Instruments Highlights Exploration Goals News and Features Multimedia Curiosity Raw Images Images Videos Audio Mosaics More Resources Mars Missions Mars Sample Return Mars Perseverance Rover Mars Curiosity Rover MAVEN Mars Reconnaissance Orbiter Mars Odyssey More Mars Missions The Solar System The Sun Mercury Venus Earth The Moon Mars Jupiter Saturn Uranus Neptune Pluto & Dwarf Planets Asteroids, Comets & Meteors The Kuiper Belt The Oort Cloud 3 min read
Sols 4368-4369: The Colors of Fall – and Mars
This image shows all the textures — no color in ChemCam remote-imager images, though — that the Martian terrain has to offer. This image was taken by Chemistry & Camera (ChemCam) aboard NASA’s Mars rover Curiosity on Nov. 18, 2024 — sol 4367, or Martian day 4,367 of the Mars Science Laboratory mission — at 02:55:09 UTC. NASA/JPL-Caltech/LANL Earth planning date: Monday, Nov. 18, 2024
I am in the U.K., where we are approaching the time when trees are just branches and twigs. One tree that still has its full foliage is my little quince tree in my front garden. Its leaves have turned reddish-brown with a hint of orange, fairly dark by now, and when I passed it this afternoon on my way to my Mars operations shift, I thought that these leaves have exactly the colors of Mars! And sure enough, today’s workspace is full of bedrock blocks in the beautiful reddish-brown that we love from Mars. But like that tree, it’s not just one color, but many different versions and patterns, all of many reddish-brown and yellowish-brown colors.
The tree theme continues into the naming of our targets today, with ChemCam observing the target “Big Oak Flat,” which is a flat piece of bedrock with a slightly more gray hue to it. “Calaveras,” in contrast, looks a lot more like my little tree, as it is more reddish and less gray. It’s also a bedrock target, and APXS and MAHLI are observing this target, too. APXS has another bedrock target, called “Murphys” on one of the many bedrock pieces around. MAHLI is of course documenting Murphys, too. Let’s just hope that this target name doesn’t get any additions to it but instead returns perfect data from Mars!
ChemCam is taking several long-distance remote micro-imager images — one on the Gediz Vallis Ridge, and one on target “Mono Lake,” which is also looking at the many, many different textures and stones in our surroundings. The more rocks, the more excited a team of geologists gets! So, we are surely using every opportunity to take images here!
Talking about images… Mastcam is taking documentation images on the Big Oak Flat and Calaveras targets, and a target simply called “trough.” In addition, there are mosaics on “Basket Dome” and “Chilkoot,” amounting to quite a few images of this diverse and interesting terrain! More images will be taken by the navigation cameras for the next drive — and also our Hazcam. We rarely talk about the Hazcams, but they are vital to our mission! They look out from just under the rover belly, forward and backward, and have the important task to keep our rover safe. The forward-looking one is also great for planning purposes, to know where the arm can reach with APXS, MAHLI, and the drill. To me, it’s also one of the most striking perspectives, and shows the grandeur of the landscape so well. If you want to see what I am talking about, have a look at “A Day on Mars” from January of this year.
Of course, we have atmospheric measurements in the plan, too. The REMS sensor is measuring temperature and wind throughout the plan, and Curiosity will be taking observations to search for dust devils, and look at the opacity of the atmosphere. Add DAN to the plan, and it is once again a busy day for Curiosity on the beautifully red and brown Mars. And — hot off the press — all about another color on Mars: yellowish-white!
Written by Susanne Schwenzer, Planetary Geologist at The Open University
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Last Updated Nov 20, 2024 Related Terms
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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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By Space Force
The Department of the Air Force recorded significant audit achievements in Fiscal Year 2024, securing remediation's for all three of its audit roadmap targets, including two material weaknesses and one significant deficiency.
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
A prototype of a robot designed to explore subsurface oceans of icy moons is reflected in the water’s surface during a pool test at Caltech in September. Conducted by NASA’s Jet Propulsion Laboratory, the testing showed the feasibility of a mission concept for a swarm of mini swimming robots.NASA/JPL-Caltech In a competition swimming pool, engineers tested prototypes for a futuristic mission concept: a swarm of underwater robots that could look for signs of life on ocean worlds.
When NASA’s Europa Clipper reaches its destination in 2030, the spacecraft will prepare to aim an array of powerful science instruments toward Jupiter’s moon Europa during 49 flybys, looking for signs that the ocean beneath the moon’s icy crust could sustain life. While the spacecraft, which launched Oct. 14, carries the most advanced science hardware NASA has ever sent to the outer solar system, teams are already developing the next generation of robotic concepts that could potentially plunge into the watery depths of Europa and other ocean worlds, taking the science even further.
This is where an ocean-exploration mission concept called SWIM comes in. Short for Sensing With Independent Micro-swimmers, the project envisions a swarm of dozens of self-propelled, cellphone-size swimming robots that, once delivered to a subsurface ocean by an ice-melting cryobot, would zoom off, looking for chemical and temperature signals that could indicate life.
Dive into underwater robotics testing with NASA’s futuristic SWIM (Sensing With Independent Micro-swimmers) concept for a swarm of miniature robots to explore subsurface oceans on icy worlds, and see a JPL team testing a prototype at a pool at Caltech in Pasadena, California, in September 2024. NASA/JPL-Caltech “People might ask, why is NASA developing an underwater robot for space exploration? It’s because there are places we want to go in the solar system to look for life, and we think life needs water. So we need robots that can explore those environments — autonomously, hundreds of millions of miles from home,” said Ethan Schaler, principal investigator for SWIM at NASA’s Jet Propulsion Laboratory in Southern California.
Under development at JPL, a series of prototypes for the SWIM concept recently braved the waters of a 25-yard (23-meter) competition swimming pool at Caltech in Pasadena for testing. The results were encouraging.
SWIM Practice
The SWIM team’s latest iteration is a 3D-printed plastic prototype that relies on low-cost, commercially made motors and electronics. Pushed along by two propellers, with four flaps for steering, the prototype demonstrated controlled maneuvering, the ability to stay on and correct its course, and a back-and-forth “lawnmower” exploration pattern. It managed all of this autonomously, without the team’s direct intervention. The robot even spelled out “J-P-L.”
Just in case the robot needed rescuing, it was attached to a fishing line, and an engineer toting a fishing rod trotted alongside the pool during each test. Nearby, a colleague reviewed the robot’s actions and sensor data on a laptop. The team completed more than 20 rounds of testing various prototypes at the pool and in a pair of tanks at JPL.
“It’s awesome to build a robot from scratch and see it successfully operate in a relevant environment,” Schaler said. “Underwater robots in general are very hard, and this is just the first in a series of designs we’d have to work through to prepare for a trip to an ocean world. But it’s proof that we can build these robots with the necessary capabilities and begin to understand what challenges they would face on a subsurface mission.”
Swarm Science
A model of the final envisioned SWIM robot, right, sits beside a capsule holding an ocean-composition sensor. The sensor was tested on an Alaskan glacier in July 2023 through a JPL-led project called ORCAA (Ocean Worlds Reconnaissance and Characterization of Astrobiological Analogs). The wedge-shaped prototype used in most of the pool tests was about 16.5 inches (42 centimeters) long, weighing 5 pounds (2.3 kilograms). As conceived for spaceflight, the robots would have dimensions about three times smaller — tiny compared to existing remotely operated and autonomous underwater scientific vehicles. The palm-size swimmers would feature miniaturized, purpose-built parts and employ a novel wireless underwater acoustic communication system for transmitting data and triangulating their positions.
Digital versions of these little robots got their own test, not in a pool but in a computer simulation. In an environment with the same pressure and gravity they would likely encounter on Europa, a virtual swarm of 5-inch-long (12-centimeter-long) robots repeatedly went looking for potential signs of life. The computer simulations helped determine the limits of the robots’ abilities to collect science data in an unknown environment, and they led to the development of algorithms that would enable the swarm to explore more efficiently.
The simulations also helped the team better understand how to maximize science return while accounting for tradeoffs between battery life (up to two hours), the volume of water the swimmers could explore (about 3 million cubic feet, or 86,000 cubic meters), and the number of robots in a single swarm (a dozen, sent in four to five waves).
In addition, a team of collaborators at Georgia Tech in Atlanta fabricated and tested an ocean composition sensor that would enable each robot to simultaneously measure temperature, pressure, acidity or alkalinity, conductivity, and chemical makeup. Just a few millimeters square, the chip is the first to combine all those sensors in one tiny package.
Of course, such an advanced concept would require several more years of work, among other things, to be ready for a possible future flight mission to an icy moon. In the meantime, Schaler imagines SWIM robots potentially being further developed to do science work right here at home: supporting oceanographic research or taking critical measurements underneath polar ice.
More About SWIM
Caltech manages JPL for NASA. JPL’s SWIM project was supported by Phase I and II funding from NASA’s Innovative Advanced Concepts (NIAC) program under the agency’s Space Technology Mission Directorate. The program nurtures visionary ideas for space exploration and aerospace by funding early-stage studies to evaluate technologies that could transform future NASA missions. Researchers across U.S. government, industry, and academia can submit proposals.
How the SWIM concept was developed Learn about underwater robots for Antarctic climate science See NASA’s network of ready-to-roll mini-Moon rovers News Media Contact
Melissa Pamer
Jet Propulsion Laboratory, Pasadena, Calif.
626-314-4928
melissa.pamer@jpl.nasa.gov
2024-162
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Last Updated Nov 20, 2024 Related Terms
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