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NASA NTRS1998

Design of Large Lightweight Space Telescope Optical Systems for the Next Generation Space Telescope

The Next Generation Space Telescope (NGST) is currently in a Pre Phase A study effort to prove feasibility of design and to show that the design can be implemented within cost constraint guidelines and meet the requirements of the science community. In an effort to achieve the science communities goals as outlined in "HST and Beyond" the NGST team has developed a government "yardstick" design of an eight meter diameter segmented telescope which would be launched in an Atlas IIAS launch vehicle to a L2 (Lagrange Point) orbit. This paper will discuss the design of the Optical Telescope Assembly (OTA) and the various issues and complications of designing lightweight optics to be placed in the environment that the NGST will encounter both during launch and during its operational mission at L2. The OTA must be lightweight but structurally must withstand the launch environment and transfer to its final L2 orbit. The OTA must be stable at L2 to provide high quality science at the cryogenic temperatures it will experience. The OTA segmented petal concept is to develop lightweight optics which can either be manipulated to achieve and maintain a desired figure or be rigid enough so that change in shape is only necessary for phasing and alignment. The secondary mirror structural mast must also be rigid with frequency responses which are not coupled to spacecraft modes in order to maintain and decenter and despace requirements.

Jacobson, Dave↗

NASA NTRS2000

Finite Element Modeling of a Semi-Rigid Hybrid Mirror and a Highly Actuated Membrane Mirror as Candidates for the Next Generation Space Telescope

Advanced space telescopes, which will eventually replace the Hubble Space Telescope (HTS), will have apertures of 8 - 20 n. Primary mirrors of these dimensions will have to be foldable to fit into the space launcher. By necessity these mirrors will be extremely light weight and flexible and the historical approaches to mirror designs, where the mirror is made as rigid as possible to maintain figure and to serve as the anchor for the entire telescope, cannot be applied any longer. New design concepts and verifications will depend entirely on analytical methods to predict optical performance. Finite element modeling of the structural and thermal behavior of such mirrors is becoming the tool for advanced space mirror designs. This paper discusses some of the preliminary tasks and study results, which are currently the basis for the design studies of the Next Generation Space Telescope.

Craig, Larry↗

NASA NTRS1982

Wide Field and Planetary Camera for Space Telescope

The Space Telescope's Wide Field and Planetary Camera instrument, presently under construction, will be used to map the observable universe and to study the outer planets. It will be able to see 1000 times farther than any previously employed instrument. The Wide Field system will be located in a radial bay, receiving its signals via a pick-off mirror centered on the optical axis of the telescope assembly. The external thermal radiator employed by the instrument for cooling will be part of the exterior surface of the Space Telescope. In addition to having a larger (1200-12,000 A) wavelength range than any of the other Space Telescope instruments, its data rate, at 1 Mb/sec, exceeds that of the other instruments. Attention is given to the operating modes and projected performance levels of the Wide Field Camera and Planetary Camera.

Lockhart, R. F.↗

NASA NTRS2011

Eyes on the Universe: The Legacy of the Hubble Space Telescope and Looking to the Future with the James Webb Space Telescope

Over the past 20 years the Hubble Space Telescope has revolutionized our understanding of the Universe. Most recently, the complete refurbishment of Hubble in 2009 has given new life to the telescope and the new science instruments have already produced groundbreaking science results, revealing some of the most distant galaxy candidates ever discovered. Despite the remarkable advances in astrophysics that Hubble has provided, the new questions that have arisen demand a new space telescope with new technologies and capabilities. I will present the exciting new technology development and science goals of NASA's James Webb Space Telescope, which is currently being built and tested and will be launched this decade.

Straughn, Amber↗

NASA NTRS2011

Eyes on the Universe: The Legacy of the Hubble Space Telescope and Looking to the Future with the James Webb Space Telescope

Straughn, Amber↗

NASA NTRS1982

Space telescope

The Space Telescope is discussed. The spacecraft, science instruments, deployment, the Space Telescope Science Institute, and astronomy are discussed.

Mcroberts, J. J.↗

NASA NTRS1982

Uranus science with space telescope

The Space Telescope Observatory, scheduled for launch in 1985, is described. The advantages of the space environment and the consequent features of ST performance are given, with Uranus observations as examples. The first generation instruments, including two cameras, two spectrographs and a high speed photometer, are discussed. The Space Telescope Science Institute, which will manage the Observatory, is discussed briefly. The potential scientific interaction with the Voyager 2 encounter of Uranus is also considered.

Caldwell, J.↗

NASA NTRS2009

Astronomy from Space: The Hubble, Herschel and James Webb Space Telescopes

Space-based astronomy is going through a renaissance, with three Great Observatories currently flying: Hubble in the visible and ultraviolet, Spitzer in the infrared and Chandra in X-rays. The future looks equally bright. The final servicing mission to Hubble will take place in February 2009 and promises to make the observatory more capable than ever with two new cameras, and refurbishment that will allow it to last at least five years. The upcoming launch of the Herschel Space Telescope will open the far-infrared to explore the cool and dusty Universe. Finally, we look forward to the launch of the James Webb Space Telescope in 2013, which wil provide a successor to both Hubble and Spitzer. In this talk, the author discusses some of the highlights of scientific discovery in the last 10 years and reveals the promise to the next 10 years.

Gardner, Jonathan P.↗

NASA NTRS2025

Navigation of the Roman Space Telescope and the Space Weather Follow-On Missions – Strategies and Pre-Mission Analyses

NASA Goddard Space Flight Center (GSFC) is supporting two large-scale Lagrange-Point Orbiting missions set to launch in the next two years; Space Weather Follow On (SWFO-L1) in 2025 and Roman Space Telescope (RST) in 2026. SWFO-L1 will operate in a Sun-Earth L1 Lissajous orbit and RST will operate in a Sun-Earth L2 quasi-halo orbit. As with many NASA missions, the engineering challenges are as unique as the scientific objectives. The navigation systems for these missions must meet the specific, demanding, and evolving needs of both spacecraft.

Navigation↗

NASA NTRS1982

Spectroscopic equipment for the Space Telescope

The Space Telescope will provide views of the Universe of remarkable clarity. Central to its capabilities is an f/24 Ritchey-Chretien telescope with 40,000 sq cm unobscured collecting area, which will provide point-source images less than 0.1 sec in radius at wavelengths below 633 nm. It will operate over the range 110 nm to 1 mm. The initial flight instrumentation includes two spectrographs, the Faint Object Spectrograph (F.O.S.) and the High-Resolution Spectrograph (H.R.S.). The F.O.S. is sensitive from 115 to 800 nm. It will provide data at resolving powers 1000-100 on extremely faint sources. The H.R.S. operates at the wavelengths 107-320 nm. It will achieve high photometric accuracy at resolving powers 100,000, in the echelle mode, or 10,000-1000 in first order, on brighter targets. The two cameras on board the Space Telescope will provide ancillary spectroscopic capabilities.

Leckrone, D. S.↗

NASA NTRS2006

Concept for a Large Scalable Space Telescope: In-Space Assembly

We present a conceptual design for a scalable (10-50 meter segmented filled-aperture) space observatory operating at UV-optical-near infrared wavelengths. This telescope is designed for assembly in space by robots, astronauts or a combination of the two, as envisioned in NASA s Vision for Space Exploration. Our operations concept for this-space telescope provides for assembly and check-out in an Earth Moon L2 (EML2) orbit, and transport to a Sun-Earth L2 (SEL2) orbit for science operations and routine servicing, with return to EML2 for major servicing. We have developed and analyzed initial designs for the optical, structural, thermal and attitude control systems for a 30-m aperture space telescope. We further describe how the separate components are packaged for launch by heavy lift vehicle(s) and the approach for the robot assembly of the telescope from these components.

Oegerle, W. R.↗

NASA NTRS2018

Breaking the Cost Curve: Applying Lessons Learned from the James Webb Space Telescope Development to Build More Cost-Effective Large Space Telescopes in the Future

This paper looks at the key programmatic and technical drivers of the James Webb Space Telescope and assesses ways to building more cost-effective telescopes in the future. The paper evaluates the top level programmatics for JWST along with the key technical drivers from design through integration and testing. Actual data and metrics from JWST are studied to identify what ultimately drove cost on JWST. Finally, the paper assesses areas where applying lessons learned can reduce costs on future observatories and will provide better insights into critical areas to optimize for cost.

ATLAST↗

NASA NTRS2016

Creating the Thermal Environment for Safely Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. The chamber was originally built to support testing of the Apollo Service and Command Module for lunar missions, but underwent major modifications to be able to test the James Webb Space Telescope in a simulated deep space environment. To date seven tests have been performed in preparation of testing the flight optics for the James Webb Space Telescope (JWST). Each test has had a uniquie thermal profile and set of thermal requirements for cooling down and warming up, controlling contamination, and releasing condensed air. These range from temperatures from 335K to 15K, with tight uniformity and controllability for maintining thermal stability and pressure control. One unique requirement for two test was structurally proof loading hardware by creating thermal gradients at specific temperatures. This paper will discuss the thermal requirements and goals of the tests, the original requirements of the chamber thermal systems for planned operation, and how the new requirements were met by the team using the hardware, system flexiblilty, and engineering creativity. It will also discuss the mistakes and successes to meet the unique goals, especially when meeting the thermal proof load.

Homan, Jonathan L.↗

NASA NTRS2006

The Road to Launch and Operations of the Spitzer Space Telescope

Spitzer Space Telescope, the fourth and final of NASA's Great Observatories, and the cornerstone to NASA's Origins Program, launched on 25 August 2003 into an Earth-trailing solar orbit to acquire infrared observations from space. Spitzer has an 85cm diameter beryllium telescope, which operates near absolute zero utilizing a liquid helium cryostat for cooling the telescope. The helium cryostat, though designed for a 2.5 year lifetime, through creative planning now has an expected lifetime of 5.5 years. Spitzer has completed its in-orbit checkout/science verification phases and the first two years of nominal operations, becoming the first mission to execute astronomical observations from a solar orbit. Spitzer was designed to probe and explore the universe in the infrared utilizing three state of the art detector arrays providing imaging, photometry, and spectroscopy over the 3-160 micron wavelength range...

infrared↗

NASA NTRS1976

TV system considerations for the Space Telescope

The Space Telescope, designed as a permanent observatory in space, will be launched into orbit, maintained, and refurbished by the Space Shuttle. One of the primary instruments to fly with the telescope is the f/24 Camera. The camera's mission requirements and their impact on the choice and design of a television system are discussed, along with the system engineering aspects of the TV system design and spacecraft design. An SEC type television camera tube was selected as the primary data acquisition sensor, because of its ability to accommodate exposure times of several hours with only modest cooling.

Lowrance, J. L.↗

NASA NTRS1976

A spectral identification technique for adaptive attitude control and pointing of the Space Telescope

The Space Telescope is a 2.4 m class aperture optical telescope having near-diffraction-limited performance. It will be placed into earth orbit by 1980 via the Space Shuttle. The problem considered is how to achieve negligible degradation of the astronomy imaging capability (to 0.005 arc second) due to smearing by pointing motions during observations. Initially, pointing instability sources were identified and a linear stability was used to assess the magnitude of elastic body modes and to design control system compensation regions necessary for subsequent adaptive control. A spectral identification technique for this adaptive attitude control and pointing has been investigated that will alleviate requirements for comprehensive dynamic ground testing. Typical all-digital simulation results describing motions of the telescope line of sight are presented.

Teuber, D. L.↗

NASA NTRS1977

The Space Telescope

The Space Telescope is a NASA program intended to launch a long-lived 2.4 meter astronomical observatory in 1983. It will contain optical and pointing systems producing a resolution of at least 0.1 arc seconds over periods of 10 hours. This capability will allow a new regime of imaging astronomical observations to be undertaken from below Lyman-alpha to the millimeter wavelength range. The optical, optical metering structure, pointing and guidance system, and control system will be described.

Odell, C. R.↗

NASA NTRS1985

Fracture analysis of radial scientific instrument module registration fittings of the space telescope

The space telescope contains various scientific instrument (SI) modules which are mounted to the Focal Plane Structure (FPS) in a statically determinate manner. This is accomplished by using three registration fittings per SI module, one resisting three translations, another resisting two and the third resisting only one. Due to thermal insulating requirements these fittings are complex devices composed of numerous pieces. The structural integrity of these fittings is of great importance to the safety of the orbiter transporting the telescope, so in addition to the stress analyses performed during the design of these components, fracture susceptibility also needs to be considered. The pieces of the registration fittings for the Radial SI Module containing the Wide Field Planetary Camera are examined to determine which would endanger the orbiter if they fractured and what is the likelihood of their fracture. The latter is stated in terms of maximum allowable initial flaw sizes in these pieces.

Springfield, C. W., Jr.↗