Astronomy

Ancient Stardust Sheds Light on the First Stars

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This research was presented in a paper entitled “Dust in the Reionization Era: ALMA Observations of a z =8.38 Gravitationally-Lensed Galaxy”
by Laporte et al., to appear in 
The Astrophysical Journal Letters.

 
This artist’s impression shows what the very distant young galaxy A2744_YD4 might look like. Observations using ALMA have shown that this galaxy, seen when the Universe was just 4% of its current age, is rich in dust. Such dust was produced by an earlier generation of stars and these observations provide insights into the birth and explosive deaths of the very first stars in the Universe. Credit: ESO/M. Kornmesser
 
Astronomers have used ALMA to detect a huge mass of glowing stardust in a galaxy seen when the Universe was only four percent of its present age. This galaxy was observed shortly after its formation and is the most distant galaxy in which dust has been detected. This observation is also the most distant detection of oxygen in the Universe. These new results provide brand-new insights into the birth and explosive deaths of the very first stars.

An international team of astronomers, led by Nicolas Laporte of University College London, have used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe A2744_YD4, the youngest and most remote galaxy ever seen by ALMA. They were surprised to find that this youthful galaxy contained an abundance of interstellar dust — dust formed by the deaths of an earlier generation of stars.

Follow-up observations using the X-shooter instrument on ESO’s Very Large Telescope confirmed the enormous distance to A2744_YD4. The galaxy appears to us as it was when the Universe was only 600 million years old, during the period when the first stars and galaxies were forming [1].

 

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‘Heartbeat Stars’ Unlocked in New Study

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Written by Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
October 21, 2016 

Heart_Beat_Stars.jpg This artist’s concept depicts ”heartbeat stars,” which have been detected by NASA’s Kepler Space Telescope and others. Image credit: NASA/JPL-Caltech

  

Matters of the heart can be puzzling and mysterious – so too with unusual astronomical objects called heartbeat stars.

Heartbeat stars, discovered in large numbers by NASA’s Kepler space telescope, are binary stars (systems of two stars orbiting each other) that got their name because if you were to map out their brightness over time, the result would look like an electrocardiogram, a graph of the electrical activity of the heart. Scientists are interested in them because they are binary systems in elongated elliptical orbits. This makes them natural laboratories for studying the gravitational effects of stars on each other.

In a heartbeat star system, the distance between the two stars varies drastically as they orbit each other. Heartbeat stars can get as close as a few stellar radii to each other, and as far as 10 times that distance during the course of one orbit.
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NASA, Citizen Scientists Discover Potential New Hunting Ground for Exoplanets

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Artist’s concept of the newly discovered disk. Credits: Jonathan Holden

 

Via a NASA-led citizen science project, eight people with no formal training in astrophysics helped discover what could be a fruitful new place to search for planets outside our solar system – a large disk of gas and dust encircling a star known as a circumstellar disk.

paper, published in The Astrophysical Journal Letters and coauthored by eight citizen scientists involved in the discovery, describes a newly identified red dwarf star, AWI0005x3s, and its warm circumstellar disk, the kind associated with young planetary systems. Most of the exoplanets, which are planets outside our solar system, that have been imaged to date dwell in disks similar to the one around AWI0005x3s.

The disk and its star are located in what is dubbed the Carina association – a large, loose grouping of similar stars in the Carina Nebula approximately 212 light years from our sun. Its relative proximity to Earth will make it easier to conduct follow-on studies.

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NASA’s Juno to Soar Closest to Jupiter This Saturday

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This dual view of Jupiter was taken on August 23, when NASA’s Juno spacecraft was 2.8 million miles (4.4 million kilometers) from the gas giant planet on the inbound leg of its initial 53.5-day capture orbit. Image credit: NASA/JPL-Caltech/SwRI/MSSS


This Saturday at 5:51 a.m. PDT, (8:51 a.m. EDT, 12:51 UTC) NASA’s Juno spacecraft will get closer to the cloud tops of Jupiter than at any other time during its prime mission. At the moment of closest approach, Juno will be about 2,600 miles (4,200 kilometers) above Jupiter’s swirling clouds and traveling at 130,000 mph (208,000 kilometers per hour) with respect to the planet. There are 35 more close flybys of Jupiter scheduled during its prime mission (scheduled to end in February of 2018). The Aug. 27 flyby will be the first time Juno will have its entire suite of science instruments activated and looking at the giant planet as the spacecraft zooms past.

“This is the first time we will be close to Jupiter since we entered orbit on July 4,” said Scott Bolton, principal investigator of Juno from the Southwest Research Institute in San Antonio. “Back then we turned all our instruments off to focus on the rocket burn to get Juno into orbit around Jupiter. Since then, we have checked Juno from stem to stern and back again. We still have more testing to do, but we are confident that everything is working great, so for this upcoming flyby Juno’s eyes and ears, our science instruments, will all be open.”

“This is our first opportunity to really take a close-up look at the king of our solar system and begin to figure out how he works,” Bolton said.

While the science data from the pass should be downlinked to Earth within days, interpretation and first results are not expected for some time.

“No other spacecraft has ever orbited Jupiter this closely, or over the poles in this fashion,” said Steve Levin, Juno project scientist from NASA’s Jet Propulsion Laboratory in Pasadena, California. “This is our first opportunity and there are bound to be surprises. We need to take our time to make sure our conclusions are correct.”

Not only will Juno’s suite of eight science instruments be on, the spacecraft’s visible light imager — JunoCam will also be snapping some closeups. A handful of JunoCam images, including the highest resolution imagery of the Jovian atmosphere and the first glimpse of Jupiter’s north and south poles, are expected to be released during the later part of next week.

The Juno spacecraft launched on Aug. 5, 2011, from Cape Canaveral, Florida. JPL manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for NASA’s Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. Caltech, in Pasadena, California, manages JPL for NASA.

More information on the Juno mission is available at: http://www.nasa.gov/juno

Follow the mission on Facebook and Twitter at: http://www.facebook.com/NASAJuno or http://www.twitter.com/NASAJuno

Gluttonous Star May Hold Clues to Planet Formation

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The brightness of outbursting star FU Orionis has been slowly fading since its initial flare-up in 1936. Researchers found that it has dimmed by about 13 percent in short infrared wavelengths from 2004 (left) to 2016 (right). Credit: NASA/JPL-Caltech

 

In 1936, the young star FU Orionis began gobbling material from its surrounding disk of gas and dust with a sudden voraciousness. During a three-month binge, as matter turned into energy, the star became 100 times brighter, heating the disk around it to temperatures of up to 12,000 degrees Fahrenheit (7,000 Kelvin). FU Orionis is still devouring gas to this day, although not as quickly. 

This brightening is the most extreme event of its kind that has been confirmed around a star the size of the sun, and may have implications for how stars and planets form. The intense baking of the star’s surrounding disk likely changed its chemistry, permanently altering material that could one day turn into planets.  

“By studying FU Orionis, we’re seeing the absolute baby years of a solar system,” said Joel Green, a project scientist at the Space Telescope Science Institute, Baltimore, Maryland. “Our own sun may have gone through a similar brightening, which would have been a crucial step in the formation of Earth and other planets in our solar system.”

Visible light observations of FU Orionis, which is about 1,500 light-years away from Earth in the constellation Orion, have shown astronomers that the star’s extreme brightness began slowly fading after its initial 1936 burst. But Green and colleagues wanted to know more about the relationship between the star and surrounding disk. Is the star still gorging on it? Is its composition changing? When will the star’s brightness return to pre-outburst levels?  

To answer these questions, scientists needed to observe the star’s brightness at infrared wavelengths, which are longer than the human eye can see and provide temperature measurements.  

Green and his team compared infrared data obtained in 2016 using the Stratospheric Observatory for Infrared Astronomy, SOFIA, to observations made with NASA’s Spitzer Space Telescope in 2004. SOFIA, the world’s largest airborne observatory, is jointly operated by NASA and the German Aerospace Center and provides observations at wavelengths no longer attainable by Spitzer. The SOFIA data were taken using the FORCAST instrument (Faint Object infrared Camera for the SOFIA Telescope). 

“By combining data from the two telescopes collected over a 12-year interval, we were able to gain a unique perspective on the star’s behavior over time,” Green said. He presented the results at the American Astronomical Society meeting in San Diego, this week. 

Using these infrared observations and other historical data, researchers found that FU Orionis had continued its ravenous snacking after the initial brightening event: The star has eaten the equivalent of 18 Jupiters in the last 80 years.

The recent measurements provided by SOFIA inform researchers that the total amount of visible and infrared light energy coming out of the FU Orionis system decreased by about 13 percent over the 12 years since the Spitzer observations. Researchers determined that this decrease is caused by dimming of the star at short infrared wavelengths, but not at longer wavelengths. That means up to 13 percent of the hottest material of the disk has disappeared, while colder material has stayed intact.    

“A decrease in the hottest gas means that the star is eating the innermost part of the disk, but the rest of the disk has essentially not changed in the last 12 years,” Green said. “This result is consistent with computer models, but for the first time we are able to confirm the theory with observations.” 

Astronomers predict, partly based on the new results, that FU Orionis will run out of hot material to nosh on within the next few hundred years. At that point, the star will return to the state it was in before the dramatic 1936 brightening event. Scientists are unsure what the star was like before or what set off the feeding frenzy.

“The material falling into the star is like water from a hose that’s slowly being pinched off,” Green said. “Eventually the water will stop.” 

If our sun had a brightening event like FU Orionis did in 1936, this could explain why certain elements are more abundant on Mars than on Earth. A sudden 100-fold brightening would have altered the chemical composition of material close to the star, but not as much farther from it. Because Mars formed farther from the sun, its component material would not have been heated up as much as Earth’s was. 

At a few hundred thousand years old, FU Orionis is a toddler in the typical lifespan of a star. The 80 years of brightening and fading since 1936 represent only a tiny fraction of the star’s life so far, but these changes happened to occur at a time when astronomers could observe. 

“It’s amazing that an entire protoplanetary disk can change on such a short timescale, within a human lifetime,” said Luisa Rebull, study co-author and research scientist at the Infrared Processing and Analysis Center (IPAC), based at Caltech, Pasadena, California.   

Green plans to gain more insight into the FU Orionis feeding phenomenon with NASA’s James Webb Space Telescope, which will launch in 2018. SOFIA has mid-infrared high-resolution spectrometers and far-infrared science instrumentation that complement Webb’s planned near- and mid-infrared capabilities. Spitzer is expected to continue exploring the universe in infrared light, and enabling groundbreaking scientific investigations, into early 2019. 

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA. Science operations are conducted at the Spitzer Science Center at Caltech. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA. 

SOFIA is a joint project of NASA and the German Aerospace Center (DLR). The aircraft is based at NASA Armstrong Flight Research Center’s facility in Palmdale, California. NASA’s Ames Research Center in Moffett Field, California, manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA) headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. 

For more information about Spitzer, visit: http://www.nasa.gov/ or http://spitzer.caltech.edu

For more information about SOFIA, visit: http://www.nasa.gov/sofia or http://www.dlr.de/en/sofia

NASA Extends Hubble Space Telescope Science Operations Contract

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Image of the Hubble Space Telescope in orbit taking photos of deep space objects. Credit NASA 

Hubble_Space_Telescope_Schematics.jpg
Components making up the Hubble Space Telescope. Credit NASA

This action will extend the period of performance from July 1 through June 30, 2021. The contract value will increase by approximately $196.3 million for a total contract value of $2.03 billion. 

This contract extension covers the work necessary to continue the science program of the Hubble mission by the Space Telescope Science Institute. The support includes the products and services required to execute science system engineering, science ground system development, science operations, science research, grants management and public outreach support for Hubble and data archive support for missions in the Mikulski Archive for Space Telescopes. 

James_Webb_Space_Telescope.jpg
To replace the Hubble in 2018, the James Webb Space Telescope is to be the premier telescope. Credit NASA

After the final space shuttle servicing mission to the telescope in 2009, Hubble is better than ever. Hubble is expected to continue to provide valuable data into the 2020’s, securing its place in history as an outstanding general purpose observatory in areas ranging from our solar system to the distant universe. 

In 2018, NASA’s James Webb Space Telescope will be launched into space as the premier observatory of the next decade, serving astronomers worldwide to build on Hubble’s legacy of discoveries and help unlock some of the biggest mysteries of the universe.

For information about NASA and agency programs, visit: http://www.nasa.gov

Clues About How Giant Black Holes Formed So Quickly

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This illustration depicts a possible “seed” for the formation of a supermassive black hole. The inset boxes at right contain Chandra (top) and Hubble (bottom) images of one of two candidate seeds, where the properties in the data matched those predicted by sophisticated models. Illustration Credit: NASA/CXC/M. Weiss

 

Using data from NASA’s Great Observatories, astronomers have found the best evidence yet for cosmic seeds in the early universe that should grow into supermassive black holes.

Researchers combined data from NASA’s Chandra X-ray Observatory, Hubble Space Telescope, and Spitzer Space Telescope to identify these possible black hole seeds. They discuss their findings in a paper that will appear in an upcoming issue of the Monthly Notices of the Royal Astronomical Society.

“Our discovery, if confirmed, explains how these monster black holes were born,” said Fabio Pacucci of Scuola Normale Superiore (SNS) in Pisa, Italy, who led the study. “We found evidence that supermassive black hole seeds can form directly from the collapse of a giant gas cloud, skipping any intermediate steps.”

Scientists believe a supermassive black hole lies in the center of nearly all large galaxies, including our own Milky Way. They have found that some of these supermassive black holes, which contain millions or even billions of times the mass of the sun, formed less than a billion years after the start of the universe in the Big Bang.

One theory suggests black hole seeds were built up by pulling in gas from their surroundings and by mergers of smaller black holes, a process that should take much longer than found for these quickly forming black holes.

These new findings suggest instead that some of the first black holes formed directly when a cloud of gas collapsed, bypassing any other intermediate phases, such as the formation and subsequent destruction of a massive star.

“There is a lot of controversy over which path these black holes take,” said co-author Andrea Ferrara, also of SNS. “Our work suggests we are narrowing in on an answer, where the black holes start big and grow at the normal rate, rather than starting small and growing at a very fast rate.”

The researchers used computer models of black hole seeds combined with a new method to select candidates for these objects from long-exposure images from Chandra, Hubble and Spitzer.

The team found two strong candidates for black hole seeds. Both of these matched the theoretical profile in the infrared data, including being very red objects, and they also emit X-rays detected with Chandra. Estimates of their distance suggest they may have been formed when the universe was less than a billion years old 

“Black hole seeds are extremely hard to find and confirming their detection is very difficult,” said Andrea Grazian, a co-author from the National Institute for Astrophysics in Italy. “However, we think our research has uncovered the two best candidates to date.”

The team plans to obtain further observations in X-rays and infrared to check whether these objects have more of the properties expected for black hole seeds. Upcoming observatories, such as NASA’s James Webb Space Telescope and the European Extremely Large Telescope, will aid in future studies by detecting the light from more distant and smaller black holes. Scientists currently are building the theoretical framework needed to interpret the upcoming data, with the aim of finding the first black holes in the universe.

“As scientists, we cannot say at this point that our model is ‘the one’,” said Pacucci. “What we really believe is that our model is able to reproduce the observations without requiring unreasonable assumptions.”

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program while the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations. 

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy in Washington.

NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission, whose science operations are conducted at the Spitzer Science Center. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado.

For more on NASA’s Chandra X-ray Observatory, visit: http://www.nasa.gov/chandra

For more on NASA’s Hubble Space Telescope, visit: http://www.nasa.gov/hubble

For more on NASA’s Spitzer Space Telescope, visit: http://www.nasa.gov/spitzer

Spitzer Telescope Maps Super Earth’s Climate

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The varying brightness of an exoplanet called 55 Cancri e is shown in this plot of infrared data captured by NASA’s Spitzer Space Telescope. Credits: NASA/JPL-Caltech/University of Cambridge

 

Observations from NASA’s Spitzer Space Telescope have led to the first temperature map of a super-Earth planet — a rocky planet nearly two times as big as ours. The map reveals extreme temperature swings from one side of the planet to the other, and hints that a possible reason for this is the presence of lava flows. 

 
 
 
 This animated illustration shows one possible scenario for the rocky exoplanet 55 Cancri e, nearly two times the size of Earth. New Spitzer data show that one side of the planet is much hotter than the other – which could be explained by a possible presence of lava pools.

Credits: NASA/JPL-Caltech

“Our view of this planet keeps evolving,” said Brice Olivier Demory of the University of Cambridge, England, lead author of a new report appearing in the March 30 issue of the journal Nature. “The latest findings tell us the planet has hot nights and significantly hotter days. This indicates the planet inefficiently transports heat around the planet. We propose this could be explained by an atmosphere that would exist only on the day side of the planet, or by lava flows at the planet surface.” 

The toasty super-Earth 55 Cancri e is relatively close to Earth at 40 light-years away. It orbits very close to its star, whipping around it every 18 hours. Because of the planet’s proximity to the star, it is tidally locked by gravity just as our moon is to Earth. That means one side of 55 Cancri, referred to as the day side, is always cooking under the intense heat of its star, while the night side remains in the dark and is much cooler. 

“Spitzer observed the phases of 55 Cancri e, similar to the phases of the moon as seen from the Earth. We were able to observe the first, last quarters, new and full phases of this small exoplanet,” said Demory. “In return, these observations helped us build a map of the planet. This map informs us which regions are hot on the planet.”

Spitzer stared at the planet with its infrared vision for a total of 80 hours, watching it orbit all the way around its star multiple times. These data allowed scientists to map temperature changes across the entire planet. To their surprise, they found a dramatic temperature difference of 2,340 degrees Fahrenheit (1,300 Kelvin) from one side of the planet to the other. The hottest side is nearly 4,400 degrees Fahrenheit (2,700 Kelvin), and the coolest is 2,060 degrees Fahrenheit (1,400 Kelvin). 

The fact Spitzer found the night side to be significantly colder than the day side means heat is not being distributed around the planet very well. The data argues against the notion that a thick atmosphere and winds are moving heat around the planet as previously thought. Instead, the findings suggest a planet devoid of a massive atmosphere, and possibly hint at a lava world where the lava would become hardened on the night side and unable to transport heat.

“The day side could possibly have rivers of lava and big pools of extremely hot magma, but we think the night side would have solidified lava flows like those found in Hawaii,” said Michael Gillon, University of Liège, Belgium. 

The Spitzer data also revealed the hottest spot on the planet has shifted over a bit from where it was expected to be: directly under the blazing star. This shift either indicates some degree of heat recirculation confined to the day side, or points to surface features with extremely high temperatures, such as lava flows. 

Additional observations, including from NASA’s upcoming James Webb Space Telescope, will help to confirm the true nature of 55 Cancrie. 

The new Spitzer observations of 55 Cancri are more detailed thanks to the telescope’s increased sensitivity to exoplanets. Over the past several years, scientists and engineers have figured out new ways to enhance Spitzer’s ability to measure changes in the brightness of exoplanet systems. One method involves precisely characterizing Spitzer’s detectors, specifically measuring “the sweet spot” — a single pixel on the detector — which was determined to be optimal for exoplanet studies. 

“By understanding the characteristics of the instrument — and using novel calibration techniques of a small region of a single pixel — we are attempting to eke out every bit of science possible from a detector that was not designed for this type of high-precision observation,” said Jessica Krick of NASA’s Spitzer Space Science Center, at the California Institute of Technology in Pasadena.

NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA.

 For more information about Spitzer, visit: http://www.nasa.gov/spitzer

Media Invited to See NASA’s Orion Crew Module for its Journey to Mars

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January 20, 2016
MEDIA ADVISORY M16-005

*** NOTE: Press release are usually published under that page “Media Releases (Information for Journalist).” These press releases are usually meetings or presentation of studies. The public will most of the time have access to view or listen to most of these, but only credentialed media can ask question.

Also, before the meeting documentation may be made available, sometimes weeks before the meeting. If the documents are embargoed, we in the press know that means the information cannot be published before the embargo date and time. We use the time to pre-write our stories and prepare questions, but the embargo must be honored by all.

–  George McGinn, Examining Life (And Things of Interest), Daily Defense News and Cosmology and Space Exploration news websites.


Orion’s pressure vessel was completed Jan. 13, 2016 at NASA’s Michoud Assembly Facility in New Orleans. The pressure vessel is the spacecraft’s underlying structure on which all of the spacecraft’s systems and subsystems are built and integrated. (Credit: NASA)

 

NASA’s Orion crew module will be available to media at two NASA locations Jan. 26th and in early February, as engineers continue to prepare the spacecraft to send astronauts deeper into space than ever before, including to an asteroid placed in lunar orbit and on the journey to Mars.

At 10:30 a.m. EST on Tuesday, Jan. 26, the agency’s Michoud Assembly Facility in New Orleans will host a media viewing and facility tour of the spacecraft’s recently completed pressure vessel, the underlying structure of the crew module, before it ships to NASA’s Kennedy Space Center in Florida.

To attend the event at Michoud, reporters must contact Chip Howat at 504-257-0478 or carl.j.howat@nasa.gov by 3 p.m. Monday, Jan. 25. International media accreditation for this event is closed.

The Orion pressure vessel provides a sealed environment for astronaut life support in future human-rated crew modules. Technicians at Michoud began welding together the seven large aluminum pieces of Orion’s primary structure in precise detail last September. At Kennedy, Orion will be outfitted with the spacecraft’s systems and subsystems, processed and integrated with NASA’s Space Launch System (SLS) ahead of their first joint exploration mission, or EM-1.

Michoud also is where the massive core stage of SLS is being manufactured. Reporters will be able to view tooling and newly manufactured hardware for SLS, and hear about mission progress from personnel across NASA.

Individuals available for interviews during the tour include:

  • Bill Hill, deputy associate administrator for Exploration Systems Development at NASA Headquarters in Washington
  • Mike Sarafin, EM-1 mission manager at NASA Headquarters
  • Mark Kirasich, Orion program manager at NASA’s Johnson Space Center in Houston
  • Scott Wilson, Orion production manager at Kennedy
  • John Honeycutt, SLS program manager at the agency’s Marshall Space Flight Center in Huntsville, Alabama
  • Steve Doering, SLS core stage manager at Marshall
  • Mike Bolger, Ground Systems Development and Operations program manager at Kennedy
  • NASA astronaut Rick Mastracchio
  • Mike Hawes, Orion program manager for Lockheed Martin
  • Jim Bray, crew module director for Lockheed Martin 

Orion will depart Michoud on or about Feb. 1 and travel to Kennedy aboard NASA’s Super Guppy airplane. Additional details for Orion’s arrival at Kennedy, including media accreditation, are forthcoming.

For more information about Orion, visit: http://www.nasa.gov/orion

-end- 

 

NASA’s LISA Pathfinder Thrusters Operated Successfully

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The LISA Pathfinder spacecraft will help pave the way for a mission to detect gravitational waves. NASA/JPL developed a thruster system onboard. (Credit: European Space Agency – ESA)

 

While some technologies were created to make spacecraft move billions of miles, the Disturbance Reduction System has the opposite goal: To keep a spacecraft as still as possible.

The thruster system, managed by NASA’s Jet Propulsion Laboratory, Pasadena, California, is part of the European Space Agency’s LISA Pathfinder spacecraft, which launched from Kourou, French Guiana on Dec. 3, 2015 GMT (Dec. 2 PST). LISA Pathfinder will test technologies that could one day allow detection of gravitational waves, whose effects are so miniscule that a spacecraft would need to remain extremely steady to detect them. Observing gravitational waves would be a huge step forward in our understanding of the evolution of the universe.

Now, LISA Pathfinder is on its way to Lagrange Point L1, about 930,000 miles (1.5 million kilometers) from Earth in the direction of the sun. L1 is a special point that a spacecraft can orbit while maintaining a nearly constant distance to Earth. This month, scientists and engineers have been switching on LISA Pathfinder’s instruments to test them in space. This has included the Disturbance Reduction System instrument computer and thrusters.

The system uses colloid micronewton thrusters, which operate by applying an electric charge to small droplets of liquid and accelerating them through an electric field, to precisely control the position of the spacecraft. Thrusters that work this way had never been successfully operated in space before LISA Pathfinder launched.

As of Jan. 10, all eight identical thrusters, developed by Busek Co., Natick, Massachusetts, with technical support from JPL, passed their functional tests. The thrusters achieved their maximum thrust of 30 micronewtons, equivalent to the weight of a mosquito. This level of precision is necessary to counteract small forces on the spacecraft such as the pressure of sunlight, with the result that the spacecraft and the instruments inside are in near-perfect free-fall. A mission to detect gravitational waves would need that level of stability.

“We reached a major milestone with this technology development,” said Phil Barela, Disturbance Reduction System project manager at JPL. “The DRS is helping point the way to a system that could be used to detect gravitational waves in the future.”

Gravitational waves are one of the last unverified predictions from the theory of General Relativity, which Albert Einstein published about a century ago. Einstein wrote that as massive bodies accelerate, such as black holes, they produce distortions in space-time. Scientists are interested in observing and characterizing these ripples in space-time so that they can learn more about the astrophysical systems that produce them, and about gravity itself. Proposed experiments to detect them from space, such as a future LISA mission, would need to measure how two freely-falling objects move ever so slightly, relative to each other, as a result of gravitational waves. In order to rule out any disturbances that could mask these waves, there must be a system to compensate for solar pressure and other factors. The Disturbance Reduction System on LISA Pathfinder will demonstrate this technology.

The Disturbance Reduction System could also lead to advanced thruster systems for other space applications. Space telescopes need to be very stable to detect distant planets in other solar systems, for example, and could use a similar system. A set of thrusters like the Disturbance Reduction System’s could also be used in small satellites to help synchronize flying patterns.

LISA Pathfinder will reach its final orbit on Jan. 22, and begin science operations on March 1. For the first phase of the mission’s science operations, a thruster technology system designed by the European Space Agency will be used. JPL’s Disturbance Reduction System will then take over in June or July, operating for 90 days. 

LISA Pathfinder is managed by the European Space Agency. The spacecraft was built by Airbus Defence and Space, Ltd., United Kingdom. Airbus Defence and Space, GmbH, Germany, is the payload architect for the LISA Technology Package. The DRS is managed by JPL. The California Institute of Technology manages JPL for NASA.