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NASA NTRS2002

Large Format Si:As IBC Array Performance for NGST and Future IR Space Telescope Applications

A mid-IR (5-30micrometer) instrument aboard a cryogenic space telescope can have an enormous impact in resolving key questions in astronomy and cosmology. A space platform's greatly reduced thermal backgrounds (compared to airborne or ground-based platforms), allow for more sensitive observations of dusty young galaxies at high redshifts, star formation of solar-type stars in the local universe, and formation and evolution of planetary disks and systems. The previous generation's largest, in sensitive IR detectors at these wavelengths are 256x256 pixel Si:As Impurity Band Conduction (IBC) devices built by Raytheon Infrared Operations (RIO) for the Space Infrared Telescope Facility/Infrared Array Camera (SIRTF)/(IRAC) instrument. RIO has successfully enhanced these devices, increasing the pixel count by a factor of 16 while matching or exceeding SIRTF/IRAC device performance. NASA-ARC in collaboration with RIO has tested the first high performance large format (1024x 1024) Si:As IBC arrays for low background applications, such as for the middle instrument on Next Generation Space Telescope (NGST) and future IR Explorer missions. These hybrid devices consist of radiation hard SIRTF/IRAC-type Si:As IBC material mated to a readout multiplexer that has been specially processed for operation at low cryogenic temperatures (below 10K), yielding high device sensitivity over a wavelength range of 5-28 micrometers. We present laboratory testing results from these benchmark, devices. Continued development in this technology is essential for conducting large-area surveys of the local and early universe through observation and for complementing future missions such as NGST, Terrestrial Planet Finder (TPF), and Focal Plane Instruments and Requirement Science Team (FIRST).

Ennico, Kimberly↗

NASA NTRS2001

Gamma Ray Large Area Space Telescope (GLAST) Balloon Flight Engineering Model: Overview

The Gamma Ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) is a pair-production high-energy (greater than 20 MeV) gamma-ray telescope being built by an international partnership of astrophysicists and particle physicists for a satellite launch in 2006, designed to study a wide variety of high-energy astrophysical phenomena. As part of the development effort, the collaboration has built a Balloon Flight Engineering Model (BFEM) for flight on a high-altitude scientific balloon. The BFEM is approximately the size of one of the 16 GLAST-LAT towers and contains all the components of the full instrument: plastic scintillator anticoincidence system (ACD), high-Z foil/Si strip pair-conversion tracker (TKR), CsI hodoscopic calorimeter (CAL), triggering and data acquisition electronics (DAQ), commanding system, power distribution, telemetry, real-time data display, and ground data processing system. The principal goal of the balloon flight was to demonstrate the performance of this instrument configuration under conditions similar to those expected in orbit. Results from a balloon flight from Palestine, Texas, on August 4, 2001, show that the BFEM successfully obtained gamma-ray data in this high-background environment.

Thompson, D. J.↗

NASA NTRS2002

Reducing the Requirements and Cost of Astronomical Telescopes

Limits on astronomical telescope apertures are being rapidly approached. These limits result from logistics, increasing complexity, and finally budgetary constraints. In an historical perspective, great strides have been made in the area of aperture, adaptive optics, wavefront sensors, detectors, stellar interferometers and image reconstruction. What will be the next advances? Emerging data analysis techniques based on communication theory holds the promise of yielding more information from observational data based on significant computer post-processing. This paper explores some of the current telescope limitations and ponders the possibilities increasing the yield of scientific data based on the migration computer post-processing techniques to higher dimensions. Some of these processes hold the promise of reducing the requirements on the basic telescope hardware making the next generation of instruments more affordable.

Smith, W. Scott↗

NASA NTRS2003

Life Cycle Testing of Viscoelastic Material for Hubble Space Telescope Solar Array 3 Damper

During the March 2002 Servicing Mission by Space Shuttle (STS 109), the Hubble Space Telescope (HST) was refurbished with two new solar arrays that now provide all of its power. These arrays were built with viscoelastic/titanium dampers, integral to the supporting masts, which reduce the interaction of the wing bending modes with the Telescope. Damping of over 3% of critical was achieved. To assess the damper s ability to maintain nominal performance over the 10-year on-orbit design goal, material specimens were subjected to an accelerated life test. The test matrix consisted of scheduled events to expose the specimens to pre-determined combinations of temperatures, frequencies, displacement levels, and numbers of cycles. These exposure events were designed to replicate the life environment of the damper from fabrication through testing to launch and life on-orbit. To determine whether material degradation occurred during the exposure sequence, material performance was evaluated before and after the accelerated aging with complex stiffness measurements. Based on comparison of pre- and post-life-cycle measurements, the material is expected to maintain nominal performance through end of life on-orbit. Recent telemetry from the Telescope indicates that the dampers are performing nominally.

Maly, Joseph R.↗

NASA NTRS2003

JSC Particle Telescope

This paper presents a detailed description of the Johnson Space Center's Particle Telescope. Schematic diagrams of the telescope geometry and an electronic block diagram of the detector telescopes' components are also described.

Badhwar, G. D.↗

NASA NTRS2003

The James Webb Space Telescope

The James Webb Space Telescope (JWST) will extend the discoveries of the Hubble Space Telescope by deploying a large cooled infrared telescope at the Sun-Earth Lagrange point L2. With a 6 m aperture and three instruments covering the wavelength range from 0.6 to 28 pm, it will provide sensitivities orders of magnitude better than any other facilities. It is intended to observe the light from the first galaxies and the first supernovae, the assembly of galaxies, and the formation and evolution of stars and planetary systems. In this talk I will review the scientific objectives, the hardware concepts and technology, and the predicted system performance.

Mather, John C.↗

NASA NTRS2003

The James Webb Space Telescope

The James Webb Space Telescope (JWST) will be a large (6m) cold (50K) telescope launched to the second Earth-Sun Lagrange point. It is the successor to the Hubble Space Telescope, and is a partnership of NASA, ESA and CSA. It's science goals are to detect and identify the first galaxies to form in the universe, to trace their assembly into the Hubble Sequence, and to study stellar and planetary system formation. JWST will have three instruments: The Near InfiaRed Camera (NIRCam) and the Near InfraRed multiobject Spectrometer (NIRSpec) will cover the wavelength range 0.6 to 5 microns, and the Mid InfraRed Instrument (MIRI) will do both imaging and spectroscopy from 5 to 28 microns.

Gardner, Jonathan P.↗

NASA NTRS2004

Telescoping Mechanics: A New Paradigm for Composite Behavior Simulation

This report reviews the application of telescoping mechanics to composites using recursive laminate theory. The elemental scale is the fiber-matrix slice, the behavior of which propagates to laminate. The results from using applications for typical, hybrid, and smart composites and composite-enhanced reinforced concrete structures illustrate the versatility and generality of telescoping scale mechanics. Comparisons with approximate, single-cell, and two- and three-dimensional finite-element methods demonstrate the accuracy and computational effectiveness of telescoping scale mechanics for predicting complex composite behavior.

Chamis, C. C.↗

NASA NTRS2004

Finding our Origins with the Hubble and James Webb Space Telescopes

NASA s Origins program is a series of space telescopes designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, I will concentrate on the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with the Hubble Space Telescope through to the present day. I will introduce several of the tools that astronomers use to measure distances, measure velocities, and look backwards in time. I will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope, which is designed to find the first galaxies that formed in the distant past. I will finish with a short discussion of other missions in the Origins theme, including the Terrestrial Planet Finder.

Gardner, Jonathan P.↗

NASA NTRS2004

Ground-Based Telescope Parametric Cost Model

A parametric cost model for ground-based telescopes is developed using multi-variable statistical analysis, The model includes both engineering and performance parameters. While diameter continues to be the dominant cost driver, other significant factors include primary mirror radius of curvature and diffraction limited wavelength. The model includes an explicit factor for primary mirror segmentation and/or duplication (i.e.. multi-telescope phased-array systems). Additionally, single variable models based on aperture diameter are derived. This analysis indicates that recent mirror technology advances have indeed reduced the historical telescope cost curve.

Stahl, H. Philip↗

NASA NTRS2004

On-Orbit Performance of the Spitzer Space Telescope

The Spitzer Space Telescope (formally known as SIRTF) was successfully launched on August 25, 2003, and has completed its initial in-orbit checkout and science validation and calibration period. The measured performance of the observatory has met or exceeded all of its high-level requirements, it has entered normal operations, and is beginning to return high-quality science data. A superfluid-helium cooled 85 cm diameter telescope provides extremely low infrared backgrounds and feeds three science instruments covering wavelengths ranging from 3.2 to 180 microns. The telescope optical quality is excellent, providing diffraction-limited performance down to wavelengths below 6.5 microns. Based on the first helium mass and boil-off rate measurements, a cryogenic lifetime in excess of 5 years is expected. This presentation will provide a summary of the overall performance of the observatory, with an emphasis on those performance parameters that have the greatest impact on its ultimate science return.

Roellig, Thomas↗

NASA NTRS2004

An Overview of the James Webb Space Telescope (JWST) Project

The JWST project at the GSFC is responsible for the development, launch, operations and science data processing for the James Webb Space Telescope. The JWST project is currently in phase B with its launch scheduled for August 2011. The project is a partnership between NASA, ESA and CSA. The U.S. JWST team is now fully in place with the recent selection of Northrop Grumman Space Technology (NGST) as the prime contractor for the telescope and the Space Telescope Science Institute (STScI) as the mission operations and science data processing lead. This paper will provide an overview of the current JWST architecture and mission status including technology developments and risks.

Sabelhaus, Phillip A.↗

NASA NTRS2004

Optical Metrology for the Segmented Optics on the Constellation-X Spectroscopy X-Ray Telescope

We present the metrology requirements and metrology implementation necessary to prove out the reflector technology for the Constellation X(C-X) spectroscopy X-ray telescope (SXT). This segmented, 1.6m diameter highly nested Wolter-1 telescope presents many metrology and alignment challenges. In particular, these mirrors have a stringent imaging error budget as compared to their intrinsic stiffness; This is required for Constellation-X to have sufficient effective area with the weight requirement. This has implications for the metrology that can be used. A variety of contract and noncontact optical profiling and interferometric methods are combined to test the formed glass substrates before replication and the replicated reflector segments.The reflectors are tested both stand-alone and in-situ in an alignment tower.Some of these methods have not been used on prior X-ray telescopes and some are feasible only because of the segmented approach used on the SXT. Methods discussed include high precision coordinate measurement machines using very low force or optical probe axial interferometric profiling azimuthal circularity profiling and use of advanced null optics such as conical computer generated hologram (CGHs).

Content, David↗

NASA NTRS2003

Finding Our Origins with the Hubble and James Webb Space Telescopes

NASA's Origins program is a series of space telescopes designed to study the origins of galaxies, stars, planets and life in the universe. In this talk, I will concentrate on the origin and evolution of galaxies, beginning with the Big Bang and tracing what we have learned with the Hubble Space Telescope through to the present day. I will introduce several of the tools that astronomers use to measure distances, measure velocities, and look backwards in time. I will show that results from studies with Hubble have led to plans for its successor, the James Webb Space Telescope, which is designed to find the first galaxies that formed in the distant past. I will finish with a short discussion of other missions in the Origins theme, including the Terrestrial Planet Finder.

Gardner, Jonathan P.↗

NASA NTRS2004

An Overview of the James Webb Space Telescope Project

The JWST project at the GSFC is responsible for the development, launch, operations and science data processing for the James Webb Space Telescope. The JWST project is currently in phase B with its launch scheduled for August 2011. The project is a partnership between NASA, ESA and CSA. The U.S. JWST team is in place with the selection of Northrop Grumman Space Technology (NGST) as the prime contractor for the telescope and the Space Telescope Science Institute (STScI) as the mission operations and science data processing lead. This paper will provide an overview of the current JWST architecture and mission status including technology developments and risks.

Sabelhaus, Phillip A.↗

NASA NTRS2003

The James Webb Space Telescope

Mather, John↗

NASA NTRS2004

Science with the James Webb Telescope

The James Webb Space Telescope (JWST) will be a large (6.5m) cold (50K) telescope launched to the second Earth-Sun Lagrange point in 2011. It is the successor to the Hubble Space Telescope, and is a partnership of NASA, ESA and CSA. Its science goals are to detect and identify the first galaxies to form in the universe, to trace the assembly of galaxies, and to study stellar and planetary system formation. JWST will have three instruments: The Near Infrared Camera and the Near Infrared multiobject Spectrometer will cover the wavelength range 0.6 to 5 microns, and the Mid Infrared Instrument will do both imaging and spectroscopy from 5 to 27 microns. In this special session, we review the status and capabilities of the observatory and instruments in the context of these major goals.

Gardner, Jonathan↗

NASA NTRS2001

A Ten-Meter Ground-Station Telescope for Deep-Space Optical Communications: A Preliminary Design

This article describes a telescope design for a 10-m optical ground station for deep-space communications. The design for a direct-detection optical communications telescope differs dramatically from a telescope for imaging applications. In general, the requirements for optical manufacturing and tracking performance are much less stringent for direct detection of optical signals. The technical challenge is providing a design that will operate in the daytime/nighttime conditions required for a Deep Space Network tracking application. The design presented addresses these requirements. The design will provide higher performance at lower cost than existing designs.

Britcliffe, M.↗