Scientists Hope Satellite Uncovers Mysteries Of Big Bang's Immediate Aftermath
After nearly a decade of planning and assembly, the Far Ultraviolet Spectroscopic Explorer satellite has taken the penultimate step toward its scheduled Feb. 18, 1999, launch.
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. of 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.
Faster, Better, Cheaper
FUSE began as a NASA-managed project in the mid-1980s. But when the budget ballooned to more than $300 million, the space agency sought a way to restructure the project. In 1995, The Johns Hopkins University proposed to NASA a way to build the satellite faster, cheaper and better than previously conceived. Hopkins assured NASA it could bring FUSE to the launchpad for about $100 million and two years earlier than originally planned. And it has.
"[Hopkins professor and FUSE principal investigator] Warren Moos 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.
Studying the Origins of the Universe
FUSE was designed to study the origin and evolution of hydrogen and deuterium, the universe's lightest elements, which were created shortly after the Big Bang, and the forces and processes involved in the evolution of galaxies, stars and planetary systems.
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.
FUSE and Ultraviolet Spectroscopy
Other satellites and instruments have been used to observe ultraviolet light. The first to view the same wavelength range as FUSE was the Copernicus spacecraft, during the 1970s. But that pioneering spacecraft's view was limited to a small portion of the Milky Way galaxy -- to a region in Earth's general neighborhood -- which astronomers suspect is not representative of the galaxy as a whole. FUSE is at least 10,000 times more sensitive than Copernicus was.
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.
How FUSE Works
FUSE will be placed in low-earth orbit, at an altitude of about 775 km (480 miles). The 18-foot-long satellite is made up of a spacecraft and an instrument. The spacecraft contains the solar panels and power supply, the controls for pointing the satellite, the communications and computer hardware and other essential equipment.
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.
Fueling the Maryland Economy
One substantial way Hopkins has been able to restructure FUSE to meet NASA's directive for making exploration missions "faster, better, cheaper" has been to rely upon the expertise of Maryland's vibrant aerospace industry.
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., the Columbia, Md., subsidiary of industry giant Lockheed Martin, 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.
Other Scientific Partners
- University of California, Berkeley, which designed the ultraviolet instrument with Hopkins and University of Colorado; also designed and built the ultraviolet detectors, which are essential components of the scientific instrument.
- University of Colorado, which designed the ultraviolet instrument with Hopkins and University of California and aligned and worked on spectrograph.
- The Canadian Space Agency, which provided the fine-error sensor, which is essential for keeping the telescope locked onto its targets. The sensor is a camera that constantly informs a computer what the telescope is looking at. It was designed and built by ComDev, a Canadian aerospace company located in Cambridge, Ontario. CSA also provided the main computer -- the Instrument Data System -- which also was designed by ComDev. The computer essentially is the brains of the instrument. Among other tasks, it relays all data from the fine-error sensor to the spacecraft, which then maneuvers the satellite so that the telescope is pointed more precisely at its target.
- The French Space Agency, CNS, provided the diffraction gratings, which perform the critical task of breaking the far-ultraviolet light into its component wavelengths for analysis.
Johns Hopkins -- A Legacy in Astrophysics Research
Johns Hopkins has been involved in astrophysics research for more than a century, since the university's first physics professor, Henry A. Rowland, perfected machines in the late 19th century that enabled him to etch very closely spaced lines onto metal or glass surfaces. During the 1950s, Hopkins instrument designer William Fastie developed a spectrometer that become a key component in numerous rocket-borne and space-borne telescopes.
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.