# Presentation: 124380

## V. System Technology for Large Space Telescopes

**Session Chair:**
**Juan A. Roman**

## Outline

**Executive Summary**
**Large Telescope Capabilities to be Validated by ST9**
**Overview and Introduction**
**Ultimate Capabilities**
**Science Mission Capabilities Time Line**
**Goal of Splinter Sessions**

## Executive Summary

**Workshop Addresses Following Technology Areas**
**Issues of large (10-25m), cryogenic (4K), low mass telescope systems.**
**Sessions Topics**
**Future space science mission needs**
**Desired workshop products**
**Technology splinter session discussions**
**Needs/potential capabilities assessments**
**Splinter Session Topics**
**Large Telescope System Simulation and Modeling**
**Materials, Structures, Actuators, and Controls for Fabrication, Packaging and Deployment of Large Telescope Systems**
**Optical Correction and Active Figure Control for Large Aperture Telescopes**
**Thermal Control at Cryogenic Temperatures for Large Aperture Telescopes**
**Structure and Control Dynamics of Large Telescope Systems**

## Executive Summary (continued)

**Key Observations and Recommendations**
**ST-9 can accelerate development of needed technology before they are mature enough to be applied in a strategic scientific mission.**
**Recommendations for ST-9 Flight Experiment**
** ****Applicable to a Far-Infrared (20 - 600********m) mission with 10 – 25m telescope at 4 K**
**ST-9 can validate several of the following critical technologies**
- Deployable low areal density aperture scalable to diameter >10m
- Passive cooling (with sunshields / radiators) to ~20 K
- Active cooling of large structures from ~20 K to ~4 K
- Integrated system modeling of end-to-end performance
- Pointing stability consistent with telescope design
- Wavefront sensing and control
**Orbit traceable to target mission (e.g., L2), however:**
- Will tolerate thermal and dynamical differences necessitated by other orbits (e.g., LEO, GTO)
- Will tolerate contamination and radiation differences

## Large Telescope Capabilities to be Validated by ST9

- * These required capabilities are a critical subset; other important capabilities may not be listed here.

## Large Space Telescopes

- A key element of the SSE mission series is a large space telescope, 10-meter diameter, cryogenically cooled to 4 K and optimized for wavelengths between 40 μm and 1 mm.
- The combination of aperture diameter and telescope temperature will provide a raw sensitivity improvement of more than a factor of 1000 over presently-planned missions,therefore, capable of conducting groundbreaking research.
- In consideration of its enormous scientific potential, such a mission was recommended by the National Academy of Sciences Astronomy Decadal Committee as "the next step in exploring this important part of the spectrum."
**State of the Art**
- The JWST is consider to be the departing point for future missions.

**Enabling Capabilities**
- Very lightweight mirrors
- High dynamic wavefront sensing and control
- Active and passive cooling below 10 K
- Validation of end-to-end models in relevant environment

**Large Space Telescopes**

**    ****Concept based on JWST technology**

**    ****Concept based on large stretched membranes**

**    ****L2, sun-synch, etc., provide stable thermal environments **

## Overview and IntroductionST-9

**Critical stepping stone toward making possible future Large Space Telescopes.**
**Will enable the next breakthrough in technology capabilities that requires in-space system validation. **
**Development of needed technology capabilities can easily take a decade or more before they are mature enough to be applied in a strategic scientific mission.**
**ST-9 can accelerate this process**
**The focus is on system "validation" to address the gaining of understandings that are useable beyond the confines of the specific hardware, e.g., scaling based on correlations with analytical models.**

## “Ultimate Capabilities”

**Some of these capabilities are:**
**Building of deployable large, low areal density mirrors and their associated structural components for operation at ambient and cryogenic temperatures.**
**Wavefront control with active control of optical elements and micro-dynamic and thermal structural effects to surpass diffraction-limited performance.**
**Providing active and passive cooling for full-aperture, all-optics cooling to ~4K and other technologies for achieving a similar reduction in thermal system noise for infrared space telescope systems. **
**Robust end-to-end modeling of telescope system and validation of system model.**

## Science Mission Capabilities Time Line

**Time**

**Technological Capability**

- ~2010

- ~2020

- ~2030

**SSE**
**Desired**
**Capabilities**

**2003**

**New Technology Demands**

**2020**

**2008**

**Areal Density Figure of Merit**

**Areal Density = Mass per unit area (****Kg/ m****2****).  It includes mirror, actuators, cables and backing structure of optical system.**

## Goal of Splinter Sessions

**Identify and refine the capabilities needed for future Large Space Telescopes missions under consideration by the Space Science Enterprise.**
**Define validation requirements for each of the technology capabilities in a quantitative manner and at a realizable level of technology maturity to support a 2008 launch date. **
**Opportunity to obtain inputs from the broadest possible base – industry, academia, government.**

## Acronyms

**ST – Space Technology**
**EELV – ****Evolved Expendable Launch Vehicle **
**L2 – Libration Point 2**
**LEO – Low Earth Orbit**
**GTO – ****Geostationary Transfer Orbit **
**JWST – James Webb Space Telescope**
**TPF – Terrestrial Planet Finder**
**SAFIR – Single Aperture Far IR telescope “sapphire”**
**SSE - Space Science Enterprise**
**SUVO – Space Ultraviolet Observatory**
**AMSD – Advanced Mirror System Demonstrator**