January 12, 2000
The spacecraft has nearly completed its shakedown phase, and its first results are already providing a wealth of new information to astronomers about the material that becomes stars, planets and ourselves.
The new findings confirming the nature of the Milky Way halo are being presented today in Atlanta at the 195 meeting of the American Astronomical Society (AAS).
The roughly football-shaped hot gas halo which surrounds our galaxy extends about 5,000 -10,000 light years above and below the galactic plane and thins with distance. One light year is almost six trillion miles.
"The hot gas halo has been known for some time, but we weren't sure how it got there or stayed hot," said FUSE co- investigator Dr. Blair Savage of the University of Wisconsin in Madison. "The new FUSE observations reveal an extensive amount of oxygen VI (oxygen atoms that have had five of their eight surrounding electrons stripped away) in the halo. Some scientists thought that ultraviolet radiation from hot stars could produce the halo, but the only way to make the observed amount of oxygen VI is through collision with the blast waves from exploding stars, called supernovae."
"Stars destined to explode don't live long, compared to stars like our Sun, so star explosions are actually a record of star formation," said Dr. George Sonneborn, FUSE project scientist at NASA's Goddard Space Flight Center, Greenbelt, MD. "By comparing supernova generated halos among galaxies, we may be able to compare their star formation histories."
"FUSE measures the pulse of the lifeblood of our galaxy, the thin gas between stars," said Dr. Warren Moos, FUSE principal investigator at Johns Hopkins University in Baltimore. "This interstellar gas courses through our veins, because dense clouds of it collapsed to form new stars and planets, including our solar system."
The FUSE observatory is now "open for business," Moos said. "After an extended on-orbit checkout and debugging period, common for complex space observatories, we are now performing observations on a routine basis for both members of the principal investigator team and the 62 guest investigators from around the world selected by NASA for the first year of operations.
"We are continuing to tune the instrument," Moos added. "In the spring we expect to begin a comprehensive study of the abundance of deuterium, a fossil atom left over from the Big Bang. As our team becomes more practiced, we need less time to optimize the instrument, and the amount of time we can spend on scientific observations will go up. This means higher scientific productivity."
FUSE is able to detect interstellar gas and determine its composition, velocity and distance by viewing bright celestial objects further away. The intervening gas selectively absorbs the light from these objects in a unique pattern of colors, depending on the composition of the gas. The spectrograph on FUSE separates the light into its component colors, similar to the way a prism separates white light into a rainbow. The resulting patterns identify the gas like optical fingerprints. When the patterns shift to different colors, velocity and distance measurements can be inferred.
The FUSE spectrograph is at least 100 times more powerful than previous instruments, helping it reveal a large number of new atomic and molecular features in interstellar gas that could only be guessed at before. The ultraviolet light analyzed by FUSE is invisible to the human eye.
FUSE scientists are also reporting early results at the AAS meeting about investigations into two other components of the galactic "circulatory system": cold clouds of molecular hydrogen where new stars are born, presented by Dr. Michael Shull of the University of Colorado, and hot gas "winds" from stars so bright they nearly blow themselves apart, presented by Dr. John Hutchings of the National Research Council of Canada.
New images related to this science, and more information about FUSE, can be found on the internet at:
University of Colorado-Boulder
Boulder, Colorado 80309-0009
Jan 12, 2000
As the most abundant element in the universe, hydrogen takes the form of molecular hydrogen, or H2, as it condenses into dark, star-forming clouds in interstellar space, said CU-Boulder Professor Michael Shull, chair of the astrophysical and planetary sciences department. Molecular hydrogen largely was hidden from view before the June 1999 launch of NASA's Far Ultraviolet Spectroscopic Explorer satellite, or FUSE, which probes the far UV radiation portion of the light spectrum invisible to the Hubble Space Telescope.
"FUSE has provided us the eyes to see molecular hydrogen with a sensitivity thousands of times greater than its predecessor satellite, Copernicus, that flew in the 1970s," said Shull, a co-investigator on the FUSE project. "We also used FUSE to detect molecular hydrogen in other galaxies like the Large and Small Magellanic Clouds, suggesting star formation proceeds in similar fashion in much different space environments."
Shull presented the new FUSE results at a press briefing held at the American Astronomical Society's 195th national meeting in Atlanta Jan. 11 to Jan. 15. Other CU-Boulder researchers involved in the molecular hydrogen study were Professor Ted Snow, doctoral student Jason Tumlinson and postdoctoral researchers Mark Giroux and Brian Rachford.
Dark molecular clouds are extremely cold, dipping below minus 300 degrees Fahrenheit, said Shull. The interstellar clouds pull together individual hydrogen atoms to form H2 molecules and soon collapse under their own gravity to begin the star formation process.
"The clouds are the star nurseries from which new stars and planetary systems form," said Shull. Stars forming in clusters in the densest portion of the interstellar clouds are undoubtedly accompanied by newly forming planets, although scientists do not yet understand the details of the process and how often planets are formed, he said.
Stars form most rapidly in the dense cores of interstellar clouds, said Shull. The young, massive stars then blow away remaining material with strong stellar winds and seed the galaxy with new star-forming material.
Giant, exploding stars known as supernovae likely created the halo of violently heated hydrogen gas enshrouding the Milky Way, said Shull. But how the hot gas is assembled into dark molecular clouds, completing the stellar life cycle, is still a mystery.
"FUSE has provided astronomers with a key means of probing the life cycles of stars, Shull said. "Understanding star formation in the Milky Way and nearby galaxies gives astronomers clues about how the first stars formed 10 to 12 billion years ago."
FUSE detects gases and determines their composition, distance and velocity by pointing at distant, bright targets such as quasars. The light absorbed by the gas clouds in between provides "optical fingerprints" that reveal the contents of the gas.
Four FUSE telescopes collect and funnel UV light into a $9 million spectrograph designed and built by CU-Boulder that breaks down the light like sunbeams passing through a prism, Shull said. The international mission involves 19 science team members from the United States, France and Canada, including five from CU-Boulder.
FUSE is a powerful telescope used to study far UV light emanating from distant stars, galaxies, quasars and interstellar gas and dust. The telescope can view light from sources up to 10 billion light-years away, while the Copernicus satellite could view only the nearest 1,000 light-years. One light-year is about six trillion miles.
Mission scientists also are using FUSE to learn more about the evolution of the early universe, including determining the amounts of primordial gases in the vast space between galaxies to understand the origin and evolution of our own galaxy, he said.
By measuring the ratio of hydrogen to deuterium -- a heavy form of hydrogen thought to have been manufactured only during the Big Bang -- FUSE scientists hope to better understand star evolution and infer primordial conditions in the universe during its first few billion years of existence, Shull said.
The FUSE spectrograph is a progenitor of the Cosmic Origins Spectrograph, a $40 million instrument selected in August 1997 by NASA for insertion on the Hubble Space Telescope. It is being designed by CU-Boulder's Center for Astrophysics and Space Astronomy and built jointly by CU and Ball Aerospace Systems Group of Boulder. The spectrograph is slated for installation on Hubble in 2003.
The FUSE spectrograph was assembled at CASA's Astrophysics Research Laboratory in the CU Research Park under the direction of Professor James Green. The FUSE effort has involved 32 CU-Boulder students, faculty and engineers, including eight undergraduates.
FUSE was developed and is operated for NASA by the Johns Hopkins University in collaboration with the University of Colorado, the University of California at Berkeley, and the space agencies of Canada and France.
For more information, please visit:
Images supporting this release are available at http://fuse.pha.jhu.edu/pubinfo/AAS195/pressinfo.html, under the section "Cold Gas".
Canadian Space Agency
St. Hubert, Quebec
A number of papers on FUSE results were presented at the conference with Canadian scientists as authors and coauthors. FUSE is a NASA Explorer Mission, funded in cooperation with the Canadian Space Agency and the Centre National d'Etudes Spatiales of France. FUSE was developed and is being operated for NASA by Johns Hopkins University (JHU) in collaboration with the University of California, Berkeley and the University of Colorado.
Canadian involvement in the FUSE program includes the provision by the Canadian Space Agency of two Fine-Error Sensors (FES). The FES instruments guide the FUSE to enable it to point in precisely the right direction to make its exacting scientific observations; they also aid in the navigation of the satellite. The Canadian Space Agency also provided support through the funding of two Canadian mission support astronomers, Dr. Alex Fullerton and Dr. Pierre Chayer, stationed at Johns Hopkins University, and partial funding of Dr. Hutchings in his capacity as Canadian Project Scientist for FUSE.
The FES instruments were built by COM DEV International of Cambridge, Ontario, under contract to the Canadian Space Agency. COM DEV also developed the Instrument Data System, the computer system that controls the FUSE telescope, under a separate contract with JHU.
The Canadian Space Agency is committed to leading the development and application of space knowledge for the benefit of Canadians and humanity. It manages and co-ordinates all of Canada's space activities and promotes the Canadian space industry among international partners.
For more detailed information on Canadian FUSE results, please consult the NRC press release.
For more information on the Canadian Space Agency involvement in the FUSE
program, please visit:
Images supporting this release are available.
National Research Council Canada
FUSE is a unique new tool for studying stellar winds as it enables us to see how different parts of the wind are moving off the star. These particular spectral lines are found only at FUSE far-UV wavelengths.
The most massive stars are so bright that they are blowing themselves apart. Such stars are more than a million times brighter than the sun, but live only one thousandth as long. A phenomenon, known as a stellar wind, blows away a large fraction of the star's initial mass during its brief 10 million year lifetime.
Stellar winds have been known since the 1960s, when the outflowing material was detected moving away at up to 3000 km/s (some 11 million km/h). Stellar winds not only affect the fate of these massive stars, but they set the upper limit to their brightness before they blow themselves apart. They are also a major way in which new elements created by the nuclear reactions that power the stars, are cycled back into space, enriching the gas that will form later generations of stars.
This drawing illustrates a stellar wind. The intense starlight pushes matter away from the star's surface. The matter accelerates and cools as it rises, until it leaves the star at high velocity. The hot matter moves slowly and cooler matter moves faster.
It has also been found more recently that stellar winds blow more slowly off the hot stars in our two small neighbouring galaxies, the Magellanic Clouds [LMC: Large Magellanic Cloud; SMC: Small Magellanic Cloud], than in our own Galaxy. This indicates that there are global differences between galaxies and the way that their stars work, which we don't understand.
This sketch illustrates how we view a stellar wind. Our telescope is off to the right. Between us and the star's surface, we see matter moving towards us that absorbs the starlight and leaves telltale dips in the spectrum of the light from the star's surface. At the same time, matter in the wind moving in other directions emits light which appears to be added to the basic starlight. Just where the dips and extra light are seen, tells us the wind's speed and structure, and where the material is.
The result appears in the FUSE data as the sketched traces show. The horizontal line is the basic starlight level. On the left we see slow moving material as a sharp dip and extra peak. We measure outflow speed as a shift to the left. The fast-moving wind parts show up as dips further to the left, and a broader speed range in the extra light.
This shows the first observations, which reveal conspicuous differences, never seen before, in the way material is blown off identical stars in the two galaxies. We see very different outflow velocities in the same material in the two stars. (The sharp dips arise in material not associated with the star so that the wind signal is sketched above them.) (1 million miles corresponds to about 1.6 million kilometers).
Astronomers have started calculating how these differences can be explained, using many such pairs of features in the FUSE data. Thus, we are on our way to understanding why stars behave differently in different galaxies. This in turn tells us how the first stars in primeval galaxies began the process of enriching their galaxies, and affecting later generations of stars we see today.
These first results show that the wavelengths unique to the FUSE instrument do indeed provide key information on Stellar Winds: large differences are seen between stars of the same mass in two different galaxies. We are a big step nearer understanding one of the major energy sources that moulded our galaxy. We have waited many years for FUSE to open up this new window on stellar evolution.
The stellar winds under investigation were independently discovered by Don Morton and John Hutchings in the 1960s. FUSE thus serves long-standing research interests of NRC scientists. In addition to the science team research, Canadian scientific proposals are guaranteed at least 10% of guest investgator time on FUSE, and many Canadians have approved programs that will be carried out this year.
The FES were designed by a team at NRC's HIA in Victoria (optical design by Chris Morbey, detector development and software design by Rick Murowinski and Tim Hardy). The detailed design and flight hardware were completed by COM DEV International of Cambridge, Ontario, under contract to the Canadian Space Agency. The NRC team has worked closely with CSA and COM DEV at all stages of the project.
FUSE is a NASA Explorer Mission, funded in cooperation with the Canadian Space Agency and the Centre National d'Etudes Spatiales of France. FUSE was developed and is being operated for NASA by the Johns Hopkins University in collaboration with the University of California, Berkeley and the University of Colorado. For more on the FES camera onboard FUSE, click on the NRC Press Release September 1998.
. NRC has the mandate to operate and administer astronomical observatories established by the Government of Canada. NRC exercises this mandate through HIA, which provides astronomical facilities, research and infrastructure to university scientists and their students. HIA has fostered many international partnerships and is renowned worldwide for its development of leading-edge instruments and software.
24 June 1999
The Far Ultraviolet Spectroscopic Explorer (FUSE) spacecraft aboard a Boeing Delta II rocket, lifted off at 11:44 a.m. EDT from Cape Canaveral Air Station, Fla. Approximately 76 minutes after launch, the spacecraft separated from the Delta II second stage.
"We're off to a great start," said David Mengers, FUSE mission manager at NASA's Goddard Space Flight Center, Greenbelt, Md. "The satellite is now in orbit, the solar arrays have deployed and all data indicates we have a healthy satellite.
At the satellite control center at Johns Hopkins in Baltimore the satellite was monitored with communications through ground stations at Hawaii, Puerto Rico, the Deep Space Network, and Tracking and Data Relay Satellites at launch.
"Over the next couple weeks The Johns Hopkins University FUSE team will checkout the spacecraft, perform calibration activities and conduct a detailed checkout of the scientific instrument," said Dennis McCarthy, FUSE project manager at The Johns Hopkins University (JHU) in Baltimore. Johns Hopkins developed FUSE for NASA.
The 3,000 pound (1,360 kilograms) satellite is currently in a circular orbit 477 miles (768 kilometers) above the Earth and will orbit about every 100 minutes.
The satellite must operate on its own most of the time, moving from target to target, identifying star fields, centering objects in the spectrograph apertures and performing the observations. A ground station located in Mayaguez, Puerto Rico will be in sight of the satellite about seven times a day for 10 minutes at a time. A commercial ground station in Hawaii also will be used to downlink data. The data is then transferred to the Johns Hopkins University in Baltimore. The FUSE mission and science control centers are located on the Johns Hopkins Homewood campus in Baltimore.
FUSE is a telescope designed for very specialized and unique tasks that are complementary to other NASA missions. The spacecraft will look at light in the far ultraviolet portion of the electromagnetic spectrum with much greater sensitivity and resolution than previous instruments. No other current telescopes can observe this important spectral region.
The FUSE satellite consists of two sections: the spacecraft platform and the science instrument. The spacecraft developed by Orbital Sciences Corporation, contains all the elements necessary for powering and controlling the satellite including the attitude control system, command and data handling, solar panels, batteries, and communications electronics and antennas.
The observatory, one of NASA's Explorer satellites, was developed by the Johns Hopkins, in collaboration with the Canadian Space Agency, the French Space Agency (CNES), University of Colorado, University of California-Berkeley, Orbital Sciences Corp., Swales Aerospace, Applied Physics Laboratory, Interface and Controls Systems Inc. and AlliedSignal Technical Services Corp.
The Goddard Center manages FUSE, one of the first missions in NASA's Origins program, for NASA's Office of Space Science, Washington, D.C. FUSE is the first NASA mission of this scope that has been developed and operated entirely by a university.
Information on the FUSE mission and NASA's Origins program can be found at: http://fuse.pha.jhu.edu
John F. Kennedy Space Center
June 21, 1999
The prelaunch news conference has been rescheduled for Wednesday, June 23 at 2 p.m. and will be carried live on NASA Television. For photographers, remote camera placement at Pad 17-A has also been rescheduled for Wednesday with departure from the NASA News Center at 11 a.m.
National Aeronautics and Space Administration
John F. Kennedy Space Center
Goddard Space Flight Center
NASA's newest space telescope, FUSE is designed to scour the cosmos for the fossil record of the origins of the universe. Scientists will use FUSE to study the earliest relics of the Big Bang-hydrogen and deuterium-to unlock the secrets of how the primordial chemical elements of which all the stars, planets and life evolved, were created and distributed since the birth of the Universe.
The FUSE spacecraft has completed final checkout at Hangar AE and was mated to the Boeing Delta II rocket at the launch pad today. The Delta fairing is to be installed around the spacecraft on June 19.
NASA Television is available on GE-2, transponder 9C located at 85 degrees West longitude. Audio only of FUSE events will also be available on the "V" circuits which may be dialed directly at 407/867-1220, 1240, 1260, 7135, 4003, 4920.
A launch Webcast will also be available on the NASA-KSC Home Page.
Johns Hopkins University
Baltimore, Maryland 21218-3843
August 26, 1998
Planned, designed and built by Johns Hopkins University, it was shipped on Aug. 13 from the university's Applied Physics Laboratory, in Laurel, Md., to the Goddard Space Flight Center in Greenbelt, Md. Scientists there will subject the instrument to a series of environmental tests. If all goes as expected, the satellite will be shipped in December to Cape Canaveral, Fla., and be readied for launch in mid-February 1999.
"[Hopkins professor and FUSE principal investigator] Warren Moos (pictured at right) and his team are to be congratulated for their accomplishment," NASA's associate administrator for science, Wesley Huntress, said in 1995 when Hopkins took over the project. "This very difficult effort, which the team succeeded in doing in a very short period of time, involved bringing down the size, complexity and cost of the mission while preserving its essential ultraviolet science."
As a result, FUSE is the first large-scale space mission to be fully planned and operated by an academic department of a university. After designing and developing it with a global team of corporate and academic partners, Hopkins will take control of the scientific mission about 100 minutes after launch and manage it from a mission control center in the Center for Physics and Astronomy on the Hopkins Homewood campus throughout its expected three-year journey.
It is the first satellite capable of viewing galaxies and faint stars at high resolution in a portion of the spectrum astronomers refer to as far- ultraviolet wavelengths. Those wavelengths are particularly revealing about the characteristics of objects and processes in space. FUSE complements other NASA missions, such as the Hubble Space Telescope, by detecting these far- ultraviolet wavelengths that are invisible to other telescopes, including Hubble. The far ultraviolet region of the spectrum can only be observed from outside the Earth's atmosphere. FUSE will enable astronomers to learn more about the secrets of galaxy evolution and star formation by analyzing clouds of gases between stars in the Milky Way and nearby galaxies.
"FUSE will investigate a fossil nucleus of the universe, deuterium, which was created three minutes after the big bang " Moos said. "Others have investigated this, but these explorations have been like attacking an enemy in a straight line. FUSE will swarm the target from all angles and provide information never before possible.
"It'll be like uncovering a really big piece in a complex jigsaw puzzle," Moos said.
The Hubble Space Telescope has higher resolution than FUSE, but FUSE can see smaller wavelengths of light, which reveal important information about the composition and characteristics of objects in space. HST can detect lower- temperature gases, and satellites sensitive to X-rays can detect higher- temperature gases, but no telescope has been able to explore the middle ground, which has remained a mystery. FUSE will bridge that gap.
The instrument, mounted on top of the spacecraft, contains all of the optics for FUSE's four aligned telescopes. Light passes into the instrument and is focused by four curved mirrors onto four spectrograph gratings. The gratings are roughly 1-foot-square pieces of glass that are etched with lines that separate the light into different bands, or wavelengths, like a prism splitting light into distinct colors. Each band reveals something about the composition or properties of objects in space. The band patterns of specific objects are recorded digitally for downlink to the ground and interpretation by scientists.
Because FUSE's orbit will straddle the equator, it is out of direct communication from Baltimore, so telephone lines link the control center to a satellite dish in Puerto Rico. Scientists will communicate with FUSE while it passes over the automated ground station at the University of Puerto Rico in Mayaguez. The automated station is linked to the control center at Johns Hopkins by an electronic connection called ISDN (Integrated Services Digital Network), which sends signals via telephone lines.
FUSE will orbit the Earth every 100 minutes, about 10 minutes of which it will be within communication range of Puerto Rico. But, because the Earth is rotating under the satellite, not all of FUSE's orbits will carry it over Puerto Rico. For many of its orbits, the satellite will never be in contact with the ground station. Consequently, satellite communications will be blacked out for about 12 hours each day, during those orbits that do not pass within range of the ground station.
That means computers on FUSE must perform important automated tasks, most importantly pointing the telescopes and making the observations.
The university decided to enter into partnerships with commercial industry to purchase existing hardware and software. In doing so, Hopkins has infused about $96 million into Maryland's economy. Maryland partners benefitting from the FUSE project include Orbital Sciences Corp., in Germantown, Md., Swales Aerospace, in Beltsville, Md., Interface Control Systems, in Columbia, Md., AlliedSignal Technical Services Corp., in Columbia, Md., The Johns Hopkins University's Applied Physics Laboratory, in Laurel, Md., NASA's Space Telescope Science Institute, located on Hopkins' Homewood campus, and NASA's Goddard Space Flight Center, in Greenbelt, Md.
In the late 1960s and 1970s, Hopkins astrophysicists -- including Moos, Paul Feldman and Arthur Davidsen -- utilized improved versions of this spectrometer on numerous successful sounding rocket flights and conducted pioneering work in ultraviolet astronomy.
In 1978, NASA selected the Hopkins Ultraviolet Telescope for development and multiple flight opportunities on space shuttles. In the late 1970s and early 1980s, Hopkins astronomers proposed successfully to have the Space Telescope Science Institute, the nerve center of the Hubble Space Telescope project, located on the Homewood campus. The university's growing reputation in astrophysics played no small role in that successful effort. This important development forever changed the face of astrophysics at Hopkins, placing it at the center of research in the field.
The 1990's have been an unparalleled decade for both astronomy and Hopkins astrophysics. The Hopkins Ultraviolet Telescope and the university's first astronaut, research scientist Samuel Durrance, flew on successful shuttle missions in 1990 and 1995. The launch of the Hubble Space Telescope in 1990 and the Hubble servicing missions in 1993 and 1997 all had substantial Hopkins involvement. Holland Ford led the team that built the COSTAR corrective optics package for Hubble. He then used the corrected telescope in 1994 to provide the most convincing evidence to date for massive black holes in the centers of some galaxies. Ford is now in charge of the Advanced Camera for Surveys, an instrument to be installed in Hubble during the third servicing mission in 2000.
The FUSE Spacecraft in a clean room at Orbital Sciences Corporation being prepared for delivery to the JHU Applied Physics Laboratory. (Photo from Mar. 1998.)