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NASA NTRS1986

The SIRTF mission

This paper describes the scientific and technical background and prospects for the Space Infrared Telescope Facility (SIRTF). SIRTF is a cryogenically-cooled, one meter-class space telescope which will be operated by NASA as an observatory for infrared astronomy, in the mid-1990's. SIRTF will provide detailed studies of even the faintest IRAS sources, important new capabilities for the study of known astrophysical phenomena, and the potential to make new and unexpected discoveries about the nature of the universe. The long-life SIRTF mission has undergone intensive review by the SIRTF Science Working Group, which was selected in mid-1984. This paper presents the outcome of that review process and describes the SIRTF program as it is now envisioned. Particular emphasis will be placed on the choice of orbit for SIRTF, the SIRTF scientific performance requirements, and the baseline design concept for the SIRTF facility and mission.

Werner, Michael W.↗
NASA NTRS1998

Solar System Studies with the Space Infrared Telescope Facility (SIRTF)

SIRTF (Space Infrared Telescope Facility) is the final element in NASA's 'Great Observatories' program. It consists of an 85-cm cryogenically-cooled observatory for infrared astronomy from space. SIRTF is scheduled for launch in late 2001 or early 2002 on a Delta rocket into a heliocentric orbit trailing the Earth. Data from SIRTF will be processed and disseminated to the community through the SIRTF Science Center (SSC) located at the Infrared Processing and Analysis Center (IPAC) at Caltech. Some 80/% of the total observing time (estimated at a minimum of 7500 hours of integration time per year for the mission lifetime of about 4 years) will be available to the scientific community at large through a system of refereed proposals. Three basic instruments are located in the SIRTF focal plane. The Multiband Imaging Photometer (MIPS), the Infrared Array Camera (IRAC), and the Infrared Spectrometer (IRS), taken together, provide imaging and spectroscopy from 3.5 to 160 microns. Among the solar system studies suited to SIRTF are the following: 1) spectroscopy and radiometry of small bodies from the asteroid main belt, through the Trojan clouds, to the Kuiper Disk; 2) dust distribution in the zodiacal cloud and the Earth's heliocentric dust ring; 3) spectroscopy and radiometry of comets; and 4) spectroscopy and radiometry of planets and their satellites. Searches for, and studies of dust disks around other stars, brown dwarfs, and superplanets will also be conducted with SIRTF. The SORTIE web site (http://ssc.ipac.caltech.edu/sirtf) contains important details and documentation on the project, the spacecraft, the telescope, instruments, and observing procedures. A community-wide workshop for solar system studies with SIRTF is in the planning stages by the author and Martha S. Hanner for the summer of 1999.

Cruikshank, Dale P.↗
NASA NTRS2003

Solar System Observing with the Space Infrared Telescope Facility (SIRTF)

SIRTF is NASA's Space Infrared Telescope Facility. Currently planned for launch on 15 Apr 2003, it is the final element in NASA's Great Observatories Program. SIRTF has an 85 cm diameter f/12 lightweight beryllium telescope, cooled to lekss than 5.5K. It is diffraction-limited at 6.5 microns, and has wavelengthcoverage from 3-180 microns. Its estimated lifetime (limited by cryogen) is 2.5 years at minimum, with a goal of 5+ years. SIRTF has three instruments, IRAC, IRS, and MIPS. IRAC (InfraRed Array Camera) provides simultaneous images at wavelengths of 3.6, 4.5, 5.8, and 8.0 microns. IRS (InfraRed Spectrograph) has 4 modules providing low-resolution (R=60-120) spectra from 5.3 to 40 microns, high-resolution (R=600) spectra from 10 to 37 microns, and an autonomous target acquisition system (PeakUp) which includes small-field imaging at 15 microns. MIPS (Multiband Imaging Photometer for SIRTF)} does imaging photometry at 24, 70, and 160 m and low-resolution (R=15-25) spectroscopy (SED) between 55 and 96 microns. The SIRTF Guaranteed Time Observers (GTOs) are planning to observe Outer Solar System satellites and planets, extinct comets and low-albedo asteroids, Centaurs and Kuiper Belt Objects, cometary dust trails, and a few active short-period comets. The GTO programs are listed in detail in the SIRTF Reserved Observations Catalog (ROC). We would like to emphasize that there remain many interesting subjects for the General Observers (GO). Proposal success for the planetary observer community in the first SIRTF GO proposal cycle (GO-1) determines expectations for future GO calls and Solar System use of SIRTF, so we would like promote a strong set of planetary GO-1 proposals. Towards that end, we present this poster, and we will convene a Solar System GO workshop 3.5 months after launch.

Cleve, J. Van↗
NASA NTRS1984

Infrared emission associated with chemical reactions on Shuttle and SIRTF surfaces

The infrared intensities which would be observed by the Shuttle Infrared Telescope Facility (SIRTF), and which are produced by surface chemistry following atmospheric impact on SIRTF and the shuttle are estimated. Three possible sources of reactants are analyzed: (1) direct atmospheric and scattered contaminant fluxes onto the shuttle's surface; (2) direct atmospheric and scattered contaminant fluxes onto the SIRTF sunshade; and (3) scattered fluxes onto the cold SIRTF mirror. The chemical reactions are primarily initiated by the dominent flux of reactive atomic oxygen on the surfaces. Using observations of the optical glow to constrain theoretical parameters, it is estimated for source (1) that the infrared glow on the SIRTF mirror will be comparable to the zodiacal background between 1 and 10 micron wavelengths. It is speculated that oxygen reacts with the atoms and the radicals bound in the organic molecules that reside on the shuttle and the Explorer surfaces. It is concluded that for source (2) that with suitable construction, a warm sunshade will produce insignificant infrared glow. It is noted that the atomic oxygen flux on the cold SIRTF mirror (3) is insufficient to produce significant infrared glow. Infrared absorption by the ice buildup on the mirror is also small.

Hollenbach, D. J.↗
NASA NTRS1990

SIRTF: Probing the dark corners of the galaxy

The Space Infrared Telescope Facility (SIRTF) is planned for launch by NASA in the mid-1990's. It will be a cryogenically-cooled observatory for infrared astronomy and will carry several focal plane instruments which will provide a wide range of imaging, photometric, and spectroscopic capabilities. SIRTF will build on the scientific and technical progress of the successful IRAS mission and take the next step in the exploration of the Universe at infrared wavelengths. Most of the observing time during the five-to-ten year SIRTF mission will be available to General Investigators, so there will be ample opportunities for the pursuit of problems originating from within the Space Life Sciences community. Here, a review is given of the capabilities of SIRTF for this style of investigation, using the study of carbon in the Galaxy as a specific example. The very high sensitivity of SIRTF's spectrometers to diffuse emission will allow studies of carbon in both the gaseous and solid phase in the interstellar medium and should be of particular importance for the identification of the carbon-bearing macromolecules believed to be responsible for the emission features identified in the near infrared. SIRTF will also carry out studies of a wide variety of evolved stars which are returning gas and solid phase carbon to the interstellar medium and contribute to our understanding of the carbon budget in the Galaxy. These studies in the area of galactic astronomy will be complemented by detailed investigations of carbon-bearing compounds in solar system objects, including the surfaces of distant asteroids and cometary nuclei which are too faint to be studied in any other way.

Werner, Michael W.↗
NASA NTRS1989

Advantages of High vs. Low Earth Orbit for SIRTF

While the subject of this workshop, which we will refer to as ET (for Enlightenment Telescope), is a dazzling successor to the Hubble Space Telescope, its location is unlikely to be the Low Earth Orbit (LEO) used by HST. Locations suggested for ET include High Earth Orbit (HEO) and the moon. The first space telescope to occupy HEO will be the liquid helium cooled Space Infrared Telescope Facility (SIRTF). The selection of HEO for SIRTF was the outcome of a recent study led by the Ames Research Center which showed significant advantages for SIRTF in HEO vs. LEO. This article summarizes the main results of that study. We begin with a review of SIRTF's rationale and requirements, in part because the IR capabilities and low temperature proposed for ET make it something of a successor to SIRTF as well as to HST. We conclude with some comments about another possible location for both SIRTF and ET, the Earth-Sun L2 Lagrangian point.

Eisenhardt, Peter↗
NASA NTRS1999

SIRTF Science Operations System Design

SIRTF Science Operations System Design William B. Green Manager, SIRTF Science Center California Institute of Technology M/S 310-6 1200 E. California Blvd., Pasadena CA 91125 (626) 395 8572 Fax (626) 568 0673 bgreen@ipac.caltech.edu. The Space Infrared Telescope Facility (SIRTF) will be launched in December 2001, and perform an extended series of science observations at wavelengths ranging from 20 to 160 microns for five years or more. The California Institute of Technology has been selected as the home for the SIRTF Science Center (SSC). The SSC will be responsible for evaluating and selecting observation proposals, providing technical support to the science community, performing mission planning and science observation scheduling activities, instrument calibration during operations and instrument health monitoring, production of archival quality data products, and management of science research grants. The science payload consists of three instruments delivered by instrument Principal Investigators located at University of Arizona, Cornell, and Harvard Smithsonian Astrophysical Observatory. The SSC is responsible for design, development, and operation of the Science Operations System (SOS) which will support the functions assigned to the SSC by NASA. The SIRTF spacecraft, mission profile, and science instrument design have undergone almost ten years of refinement. SIRTF development and operations activities are highly cost constrained. The cost constraints have impacted the design of the SOS in several ways. The Science Operations System has been designed to incorporate a set of efficient, easy to use tools which will make it possible for scientists to propose observation sequences in a rapid and automated manner. The use of highly automated tools for requesting observations will simplify the long range observatory scheduling process, and the short term scheduling of science observations. Pipeline data processing will be highly automated and data-driven, utilizing a variety of tools developed at JPL, the instrument development teams, and Space Telescope Science Institute to automate processing. An incremental ground data system development approach has been adopted, featuring periodic deliveries that are validated with the flight hardware throughout the various phases of system level development and testing. This approach minimizes development time and decreases operations risk. This paper will describe the top level architecture of the SOS and the basic design concepts. A summary of the incremental development approach will be presented. Examples of the unique science user tools now under final development prior to the first proposal call scheduled for mid-2000 will be shown.

Green, William↗
NASA NTRS1987

Using SIRTF to study extragalactic star formation

SIRTF, the Space Infrared Telescope Facility, is a NASA mission to provide a long lifetime, sensitive and flexible infrared observatory in space. SIRTF will be able to study selected objects with a sensitivity over 5,000 time better than the IRAS survey limits, and will provide photometric and low to medium resolution spectroscopic data over almost nine octaves from 1.8 to 700 micron wavelength. The baseline SIRTF design has an 85 cm telescope with optics and control system designed for diffraction limited operation at 4 micron and longer wavelengths. SIRTF will be able to measure important cooling lines from neutral regions, such as the 157 micron line, and lines from H II regions such as the 88 micron line. SIRTF will also be able to survey small areas of the sky to the confusion limit in the 3 to 700 micron region.

Wright, Edward L.↗
NASA NTRS1987

Servicing operations for the SIRTF Observatory at the Space Station

This paper describes the servicing requirements, plans, and proposed Space Station-based servicing operations for the Space Infrared Telescope Facility (SIRTF) Observatory. SIRTF is a cryogenically-cooled, long-life, one meter class space telescope which will be operated by NASA as a free-flying observatory for infrared astronomy, in the mid-1990's. To achieve its 5-year lifetime requirement (10 year goal), SIRTF must be replenished periodically with cryogenic helium and have its life-limited modular subsystems replaced; capability for contingency repair of warm components will also be provided in the Observatory design. A general description of the SIRTF Observatory is given, including options for the support systems (spacecraft). The overall servicing philosophy and plans are addressed with scheduling and needed support elements described. A proposed Space Station-based servicing scenario is described, including orbital transfer, servicing and checkout operations. A detailed description and timeline for liquid helium replenishment operations is provided, including a conceptual design and technology development program for the cryogenic helium transfer dewar (tanker). Finally, a preliminary SIRTF spares/logistics philosophy is outlined, including tradeoffs to be considered.

Wiltsee, Christopher B.↗
NASA NTRS1992

Telescience Testbed Program: A study of software for SIRTF instrument control

As a continued element in the Telescience Testbed Program (TTP), the University of Arizona Steward Observatory and the Electrical and Computer Engineering Department (ECE) jointly developed a testbed to evaluate the Operations and Science Instrument System (OASIS) software package for remote control of an instrument for the Space Infrared Telescope Facility (SIRTF). SIRTF is a cryogenically-cooled telescope with three focal plane instruments that will be the infrared element of NASA's Great Observatory series. The anticipated launch date for SIRTF is currently 2001. Because of the complexity of the SIRTF mission, it was not expected that the OASIS package would be suitable for instrument control in the flight situation, however, its possible use as a common interface during the early development and ground test phases of the project was considered. The OASIS package, developed at the University of Colorado for control of the Solar Mesosphere Explorer (SME) satellite, serves as an interface between the operator and the remote instrument which is connected via a network. OASIS provides a rudimentary windowing system as well as support for standard spacecraft communications protocols. The experiment performed all of the functions required of the MIPS simulation program. Remote control of the instrument was demonstrated but found to be inappropriate for SIRTF at this time for the following reasons: (1) programming interface is too difficult; (2) significant computer resources were required to run OASIS; (3) the communications interface is too complicated; (4) response time was slow; and (5) quicklook of image data was not possible.

Young, Erick T.↗
NASA NTRS1994

Arrays: The heart and soul of SIRTF

This pape describes the status of NASA's Space Infrared Telescope Facility (SIRTF) program. SIRTF will be a cryogenically cooled observatory for infrared astronomy from space and is planned for launch early in the next decade. It will be the first cryogenic space observatory to make extensive use of the powerful infrared detector array technology discussed at this conference. We summarize a newly developed SIRTF mission concept and show how the availability of detector arrays has shaped the scientific rationale for SIRTF, and how the arrays themselves have become part of the definition of the SIRTF mission.

Werner, Michael W.↗
NASA NTRS1982

SIRTF - The Shuttle Infrared Telescope Facility

The Shuttle Infrared Telescope (SIRTF) is a 1-m class cryogenically cooled telescope to be operated from the shuttle as a facility for infrared astronomy. By exploiting the very low infrared background of space, SIRTF will achieve 100 to 1000 times the sensitivity currently attainable at infrared wavelengths between 2 and 200 microns. The scientific requirements of SIRTF, the current design concept, and the scientific capabilities of the systems are reviewed. We also review recent experimental results showing that mirrors made of glassy materials may be suitable for use in large cryogenic telescopes such as SIRTF.

Werner, M. W.↗
NASA NTRS1982

SIRTF - The Shuttle Infrared Telescope Facility

The Shuttle Infrared Telescope (SIRTF) is a 1-m class cryogenically cooled telescope to be operated from the Shuttle as a facility for infrared astronomy. By exploiting the very low infrared background of space, SIRTF will achieve 100 to 1000 times the sensitivity currently attainable at infrared wavelengths between 2 and 200 microns. The scientific requirements of SIRTF, the current design concept, and the scientific capabilities of the systems are reviewed. Recent experimental results are also reviewed showing that mirrors made of glassy materials may be suitable for use in large cryogenic telescopes such as SIRTF. Previously announced in STAR as N82-32207

Werner, M. W.↗
NASA NTRS1984

SIRTF: The next step

The scientific and technical background and prospects for the space infrared telescope facility (SIRTF) are described. This facility is a superfluid-helium-cooled, 0.85-meter infrared telescope to be placed in orbit in 1993. It is designed to carry out photometry over the wavelength range 2 to 700 micrometers, and diffraction-limited imagery in either broad or narrow spectral bands over the range 1.8 to 200 micrometers. It is proposed that SIRTF measure spectra in the range 2.5 to 200 micrometers with resolving power between 50 and 1000 and that the focal plane contain about 20,000 detector elements, both discrete and in arrays. The SIRTF observatory is designed to be a long-lived facility providing opportunities for general investigations by the entire scientific community. For following up the all-sky survey carried out by the Infrared Astronomical Satellite (IRAS), SIRTF is ideal. It can do a deep survey to flux levels 5000 times fainer than IRAS and can obtain spectra of even the faintest IRAS sources.

Gillett, F. C.↗
NASA NTRS1989

Straylight analysis of an aperture shade off-set from the SIRTF optical axis

Adoption of an aperture shade whose axis is offset from the optical axis of the SIRTF telescope has been proposed by Davis (1988). Moving the high side of the asymmetric (truncated) shade away from the optical axis can equalize the barrel baffle lengths illuminated by the aperture shade and reduce the dimensions of both the barrel baffle and aperture shade. The stray-light performance of this revised design is compared to that of the SIRTF baseline design, which uses a coaxial asymmetric aperture shade. Both designs incorporate a back focal distance of 100 cm and Davis's specifications for the primary and secondary cone baffles. Adoption of an offset aperture shade for SIRTF would slightly degrade its performance but would not violate any of the stray-light requirements. The SIRTF goal of natural-background-limited observations can be met with known blacks, Class 750 mirror contamination, and either aperture shade configuration.

Dinger, Ann St. Clair↗
NASA NTRS1990

SIRTF high earth orbit mission conceptual structural design and analysis

The Space Infrared Telescope Facility (SIRTF) is a cryogenically cooled, space based, one meter class telescope for infrared astronomy. A recent mission option study has moved SIRTF from a previous low earth orbit (900 km) shuttle launched design to a high earth orbit (100,000 km) Titan IV/Centaur launched design. The mission option study requirements and trades relating to the structural configuration and the chosen SIRTF design are described. Also discussed is a dynamic stress analysis of the new SIRTF baseline structural design which has been performed using finite element modeling and simulated launch interface loads.

Chang, LI↗
NASA NTRS1992

SIRTF - Space Infrared Telescope Facility

SIRTF (Space Infrared Telescope Facility), a one meter class cryogenically cooled observatory for infrared astronomy, is briefly discussed. The characteristics of the Infrared Array Camera, Infrared Spectrograph, and Multiband Imaging Photometer on SIRTF are summarized and the SIRTF characteristics are compared with those of IRAS. The key scientific aims and capabilities of SIRTF are outlined.

Erickson, E. F.↗
NASA NTRS1991

SIRTF focal plane technologies

The Space Infrared Telescope Facility (SIRTF) will have three science instruments, the Infrared Array Camera (IRAC) which will obtain multispectral images between 1.8 micron and 26 microns, the Infrared Spectrometer (IRS) which is a set of two dispersive spectrometers covering the wavelength range between 2.5 and 200 microns, and the Multiband Imaging Photometer for SIRTF (MIPS) which is a general-purpose photometric instrument which operates between 30 and 1,200 microns. Taken together, the full wavelength range of these instruments extends from 1.8 micron to 1,200 microns, equivalent to nearly a factor of 700 in photon energy and diffraction limited image size. In addition to supporting this unprecedented spectral and optical coupling requirement, the SIRTF detectors must operate at lower temperatures than previously demonstrated and be optimized for new levels of performance in order to achieve the goals of the science mission. Thus, development of the detector arrays for the SIRTF instruments is one of the most challenging aspects of the instrument development activities.

Capps, Richard W.↗