November 11, 1999
"We are designing mirrors that will be very, very small, move independently and be able to withstand the very cold temperatures and extreme conditions of space," says Ernie Garcia, the Sandia engineer leading the mirror development effort.
The mirrors, each slightly larger than a cross section of a human hair, will be sensitive to infrared radiation and, as a result, will be able to detect faint signals from the first billion years after the Big Bang. This will help scientists better understand the origins of the universe.
Aware of Sandia's advancements in microelectromechanical systems (MEMS) technology, NASA approached the Labs last year about developing prototype MEMS mirrors that could be part of the NGST, tentatively scheduled for launch in 2008. The one-year contract began in January, and nine months later Garcia had functioning mirrors to show the agency.
The fast turnaround at Sandia's Microelectronics Development Laboratory (MDL), which fabricated the mirrors, made it possible for Garcia to provide NASA with a working device quickly.
In September Garcia demonstrated to NASA/Goddard Space Flight Center in Greenbelt, Md., an array of working mirrors, each 100 microns by 100 microns with 1-micron gaps between adjacent mirrors, lined up in rows of three. Each row tilted 10 degrees in unison -- a large angle for this design. (One hundred microns is slightly larger than the diameter of a human hair.)
"Getting these miniaturized mirrors to rotate to such a large angle was a real milestone in the research," Garcia says. "It's something that NASA wanted, and we did it."
The goal is to have four million of these independently moving mirrors in the NGST. Each mirror could be tilted in different directions to redirect optical signals to an infrared detector.
In light of the success of getting the mirrors to rotate at large angles, Garcia is hopeful that NASA will extend the contract to continue the research.
NASA is pursuing the NGST as the successor to the Hubble Space Telescope in an effort to observe the "Dark Zone," a period 100 million to one billion years after the Big Bang when primordial seeds began to evolve into the galaxies and stars known today. It would also see formations in the present day universe. The Hubble has provided data about more recent formations, but has been unable to detect the earlier stars that fall in the infrared range because it was designed as an optical telescope.
The NGST, on the other hand, will be extremely sensitive to infrared radiation, and with its large light-gathering mirror and superb resolution, will be capable of detecting the earlier signals. The new telescope will be placed in orbit well beyond the Earth's moon to reduce stray light and achieve the cold temperatures needed to observe in the infrared.
Currently three entities -- Lockheed Martin, Goddard Space Flight Center, and TRW -- are studying different design approaches for the NGST. Each approach includes adjustable thin mirrors, deep space orbits, fast- steering mirrors for fine guidance, and infrequent contact with the ground. They differ in the areas of mirror construction, materials and deployment, detector types, sunshield types, vibration control and launch vehicles. Eventually NASA will select one design from the three for the final NGST.
The mirrors Garcia is designing could go into any one of the three NGST approaches as part of the Integrated Science Instrument Module that will also include cameras, spectrographs, and infrared detectors. The micromirrors will work in conjunction with a very large mirror -- possibly eight meters in diameter -- that will collect light from a broad area in space. When an object is encountered that appears interesting, the smaller micromirrors would be tilted to reflect the image from only that area, beaming the information to an infrared detector.
Garcia says he still faces several challenges in developing moving mirrors for the NGST.
One is making the mirrors able to function in extremely cold temperatures.
"Instrument operating temperatures in space can be 30 degrees K [-405 degrees F] or lower," Garcia says. "That means we have to build these mirrors a special way so that they won't break at such extremes."
The mirrors are built by depositing thin films of polycrystalline silicon on a silicon wafer. The first layer, called poly0, contains connection wires. The others, poly1, poly2, and poly3, are mechanical layers that allow the MEMS device to move. Garcia plans to soon add on top of the poly3 a final thin layer of gold to reflect infrared light.
Therein lies the problem in cold temperatures, Garcia says.
"Different materials shrink at different rates when subjected to temperature changes," Garcia says. "As the temperature is reduced, the gold layer will shrink faster than the polysilicon. This will cause stress. If the stress levels get too high, the mirror could break or deform or the gold could peel away. We have to come up with the smallest thickness of gold so that it doesn't cause excessive stress, but yet be thick enough to reflect the infrareds."
The MDL will soon begin fabricating an improved mirror design, which will be cold-tested by NASA next year in a cryogenic chamber where the conditions of deep space will be simulated.
Another challenge Garcia is concurrently striving to resolve is that of making each of the mirrors move independently. The new design, which will soon be fabricated at the MDL, has each row tilting in unison and one mirror in the middle tilting and moving independently. But doing this for each of the four million mirrors is a major hurdle.
Find out more about the Next Generation Space Telescope at the Web site.
Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major research and development responsibilities in national security, energy and environmental technologies, and economic competitiveness.
POSSIBLE SPACE EXPLORATION -- Sandia researchers Ernie Garcia (standing) and Ed Vernon examine a micromirror that may one day be part of the Next Generation Space Telescope. (Photo by Randy Montoya) [Image 2]
MIRROR IN MOTION -- A micromirror developed by Sandia engineer Ernie Garcia is pictured in the tilted position. Each mirror has a diameter slightly larger than a human hair.
ESA Science News
17 Sep 1999
More than 400 people participated in a four-day conference, 13-16 September, in Hyannis, Massachussets USA. The topic of the meeting was the Next Generation Space Telescope (NGST). The participants included scientists, representatives from the space industry and representatives from three space agencies: NASA (National Aeronautics and Space Agency), ESA (European Space Agency) and CSA (Canadian Space Agency).
The original idea that started NGST was a wish "to visit the time when galaxies were young". Or in other words to continue where Hubble Space Telescope (HST) leaves off. HST has observed galaxies back to when the Universe was only a tenth of its present age, but it was discovered that though these galaxies were in their childhood, they were in no way in their infancy. What is really behind galaxy birth and evolution remains a mystery, and as more facts are unveiled, the story of galaxy formation becomes more and more complex. To probe even deeper into the Universe, it is necessary to see to higher redshift (all objects in the Universe look redder the farther away they are) -- and this is where NGST comes in.
In many ways NGST can be seen as a continuation, or a complement, to the spaceborne observatories which exist today or are under development. NGST's need to see the redshifted galaxies calls for measurements in infrared light. ESA's ISO (Infrared Space Observatory) has been very successful in making observations in infrared light, and in many respects NGST will continue and expand on this work.
The plans for NGST have now matured to such a degree that numerous fairly detailed suggestions for the different parts of NGST were presented. The basic ideas were generally agreed upon: NGST will be a very large telescope -- 8 metres in diameter -- with the capacity to record extremely faint light in the infrared (also known as heat radiation). Due to current limitations in the size of rockets, its mirror will have to be segmented and unfolded after launch.
The scientists all agree that the natural arena for the next decade of astronomical discoveries will be the infrared domain. As the Dutch astronomer from Leiden Observatory, Ewine van Dishoeck elegantly puts it: "The last few years of discoveries have shown us that there are enormous amounts of dust both in the local and in the distant Universe. In the infrared NGST will enable us to probe deep within the dusty clouds and find the true origin of the galaxies, the stars and the planets". The increase in sensitivity over existing telescopes will be from a factor of more than a 100 to infinity, since some of the wavelengths hitherto have been hidden completely from our view from the ground. She continues: "We will be able to see organic molecules and planetary systems forming around newborn stars".
Canadian astronomer Simon Lilly talked with passion of the perspectives of taking very deep images each lasting hundreds of hours: "NGST will literally enable us to see the first light in the Universe! We will be able to see the first stars and galaxies form."
Incredible technological challenges are to be faced during the development of NGST. To mention a few:
Current plans for financing NGST foresee a possible ESA participation at the 15% level -- as with the HST. The Canadian CSA plans to participate at the 5% level.
With regard to the future collaboration a so-called "partnership concept document" has been signed by ESA and NASA which outlines the framework for ESA's extension of the current HST participation and possible involvement in NGST. Although this document is not yet a formal agreement, it clearly demonstrates ESA's strong wish to participate in this very important project. The final confirmation will await decisions to be made in the 2001/2002 timeframe.
Images supporting this release are available.
Paris, 17 June 1998
Prof. Roger Bonnet said it was important for Europe to make an informed decision in the next few years on whether to support NASA's proposed New Generation Space Telescope (NGST), a follow-on programme to the Hubble Space Telescope.
NGST's observing capabilities will far extend the reach of existing ground or space-based telescopes, providing the opportunity for the first time to look back through eons of time to the very first stars and galaxies in the Universe.
With an aperture greater than four metres, NGST could also provide European astronomers with a crucial complement to some of ESA's planned future space projects, like FIRST (the Far InfraRed Submillimetre Telescope) and Planck (a mission to study the cosmic background radiation field).
NASA and ESA are already involved in preliminary NGST studies but Europe has yet to make a commitment to support the programme. NASA wants to start formal development in 2003, with a launch currently planned for 2007. This week's conference at Liege in Belgium was the first opportunity for many astronomers to exchange ideas and compare technological notes on a Next Generation Space Telescope. It also provided a forum for representatives of Europe's space industry to discuss the technological challenges presented by such a project.
Prof. Bonnet said: "From recent experience it is clear that the best scientific results in astronomy and astrophysics are obtained by coordinated observations in different wavelength ranges.
"The joint effort of the European space programme and of the various large European ground observatories currently allows European astronomers to be on the front-line of astrophysics research."He said that ESA - if supported programmatically and financially by its member states - is willing to discuss with NASA a mutually fruitful form of NGST participation.
But Prof. Bonnet stressed that for this type of collaboration to be approved it remained crucial that the European share contained both scientific and technological "qualifying activities".
One possibility is to use one of ESA's "flexi-missions" foreseen in Horizon 2000+, the agency's long term science plan. The Horizon 2000+ report recommends that ESA consider the development of infrared detectors and perform technological studies on lightweight, passively cooled, high optical-quality mirrors for use in the 2-100 micron part of the spectrum.
European scientists and astronomers are enthusiastic users of the Hubble Space Telescope, currently occupying some 20 percent of its total observing time.
Activities are managed through the European Coordinating Facility (ECF), which was set by ESA at Garching near Munich, Germany, alongside the base of the European Southern Observatory (ESO).
In return for a share of Hubble observing time for European astronomers, ESA provided a number of the telescope's key features, including the faint object camera and the solar panels.
Information and images of NGST can be found on:
NASA Headquarters, Washington, DC
Goddard Space Flight Center, Greenbelt, MD
Space Telescope Science Institute, Baltimore, MD
June 8, 1998
The Space Telescope Science Institute, located at the Johns Hopkins University, has been operating the science program for the Hubble Space Telescope since 1983.
"We looked through a microscope to decide who would operate the Next Generation Space Telescope," said NASA Administrator Daniel S. Goldin. "NASA and the scientific community had to determine who had the right facilities, who had the right experience, who was the best. The clear choice was Baltimore's Space Telescope Science Institute."
"The Space Telescope Science institute has greatly served the interests of the global astronomical community, while producing a steady stream of impressive new discoveries," added Dr. Wesley T. Huntress, Jr., Associate Administrator for NASA's Office of Space Science, Washington, DC. "With its selection as the Next Generation Space Telescope Science Institute, we can now count on at least a seven-year continuation of their outstanding efforts, rather than closing the doors to the facility after the Hubble mission ends in 2010."
The NGST is one of the cornerstone missions of the Astronomical Search for Origins and Planetary Systems, one of the major thrusts of NASA's Space Science program. The NGST will provide a critical follow-on to the Hubble Space Telescope, and continue to deliver world-class optical and infrared science well into the second decade of the new millennium.
A goal of the Next Generation Space Telescope is to observe the first stars and galaxies in the Universe to further our understanding of how it formed following the Big Bang. NGST will have capabilities currently unavailable in existing ground-based or space telescopes.
NGST studies are underway and NASA plans to start formal development of the NGST in 2003, with a projected launch in 2007. NGST has a planned operational lifetime of ten years, and NASA expects that the operations cost for NGST will be in a range from $15 million to $25 million per year. The Association of Universities for Research in Astronomy (AURA) currently operates the Space Telescope Science Institute under contract to NASA. Possible adjustments to the existing contract, and the means by which selection and award will be made for NGST work, are under review.
NASA learned from its development of the Hubble that it was important to involve scientists early in the major mission science and operations planning. "We felt it was imperative to identify an NGST Science and Operations Center as soon as possible," said Huntress. "Through our analysis and consultation with our advisory committees, it became apparent that the most cost-effective and scientifically sound way to proceed was to expand the Institute's responsibilities to include the management of NGST."
The Space Telescope Science Institute presently has a combined staff of approximately 470 people, including 143 Ph.D. astronomers and scientists from the U.S. and the European Space Agency Additional information about the NGST is available on the Internet at: http://www.ngst.nasa.gov.
A photo, caption and other information related to this release is available on the Internet.
Upper left: The Goddard Space Flight Center-led team developed this lightweight design for NGST. It incorporates many of the features found in the other designs: a deployable, 26-foot-wide (nearly 8 meters) primary mirror, a large deployable sunshade to shield the optics, and an orbit 930,000 miles (1.5 million kilometers) from Earth at the L2 Lagrangian point, a balancing point between the gravitational tug of the Earth and the Sun. The spacecraft has a deployable sunshade, an umbrella that will keep the telescope chilled -370 degrees Fahrenheit to -298 degrees Fahrenheit, which allows it to see the faint infrared glow of distant objects. With this design, the telescope can view about 40 percent of the sky at any time.
Upper right: This design by Ball Aerospace features four widely separated sunshields that are effective in reducing the temperature of the telescope optics and the science instrument compartment. The deployable primary mirror is mounted on three hinged slices of a 26-foot (8 meters) circular structure. By rolling the spacecraft so that the sunshade is always perpendicular to the Sun, the telescope can view half of the sky. The Ball model is designed for launch to L2 or similar orbits.
Lower left: This Lockheed-Martin design emphasizes simplicity and features a monolithic, 20-foot-wide (6 meters) primary mirror and rings of metal shields. The telescope would be launched into a highly elliptical orbit around the Sun. The elliptical orbit would take the telescope beyond Mars and almost to the inner portions of the asteroid belt. At this distance from the Sun, scattered sunlight and infrared light from dust in our solar system is 10 to 30 times dimmer than what is seen by orbiting spacecraft near Earth. The large deployable solar array is required to provide sufficient power for the spacecraft and communications when it is far from the Sun.
Lower right: Based on a proven technology for deploying large microwave antennae, the TRW design uses six hexagonal mirrors (10 feet or 3 meters between edges), which are stacked above a seventh central hexagonal mirror and are deployed and locked once the spacecraft reaches the L2 orbit. Like the Ball design, the TRW telescope can point to any target over more than half of the sky. The TRW sunshade design features many shields that are deployed with masts and wires.
After a National Academy of Sciences panel recommended establishment of a University-based institute to conduct science planning and operations for the Hubble Space Telescope, AURA chose JHU as a partner for its proposal to manage the institute for NASA. In 1981 NASA selected the AURA/JHU team from among several competing organizations and universities, and the STScI was established at Hopkins, initially in what is now Krieger Hall - then known as Rowland Hall and home to the JHU Department of Physics (now Physics and Astronomy). STScI moved into its present facility on San Martin Drive in 1983.
The scientific and technical staff of the Institute benefit from their immediate proximity to a University that is vitally involved in astronomy and space research, while faculty and students at JHU similarly benefit from their close interactions with the staff and visitors to the STScI. Over the years a number of scientists at the Institute have held joint appointments in JHU's Department of Physics and Astronomy, and both undergraduate and graduate students at Hopkins have done research at STScI. Johns Hopkins faculty members, students, and staff have contributed significantly to the design of several instruments used on Hubble, both past and future, and have participated vigorously in making observations and discoveries with the telescope.
STScI/JHU Connection information provided by Arthur Davidsen, professor in the department of Physics and Astronomy, The Johns Hopkins University
PHOTO NO.: STScI-PRC98-20
NASA SELECTS HOME FOR NEXT GENERATION SPACE TELESCOPE
A photo and caption are available via the Internet at