The current NASA astronomy science centers provide a wide variety of services and functions, which are detailed below and in Appendix A. Overall, these functions center on the dual goals of (1) achieving optimal quality and broad dissemination of data at a reasonable cost through an effective interface between scientists, engineers, and data managers and (2) promoting public awareness of the specific mission. The centers can enable the achievement of these goals by serving specific functions.
A NASA astronomy science center serves as the link between a spacecraft and scientists on the ground. The spacecraft can be operated either by the NASA astronomy science center itself or by another entity such as a NASA field center. The NASA astronomy science center, in coordination with a distinct operations center if there is one, integrates the tasks supporting the functionality of the satellite, for example, maneuvers of the satellite in space and operation of the instruments on board, with the observations specified by the astronomer to obtain the needed scientific result. The tasks include planning and optimizing the observing schedules; transmitting the commands to the spacecraft instruments; maintaining the correct pointing of the satellite; guiding on the target; ensuring the successful transmission of data from the instruments to the ground and ultimately to the scientist; and managing target-of-opportunity programs that attempt to observe unforeseen but important transient astronomical events such as supernovae.
One essential function of a NASA astronomy science center is ensuring the optimum scientific performance and utilization of all instruments onboard a spacecraft and the transmission of the current state of the instrument performance to the observer. The instrument support includes (1) documenting the instrument’s performance; (2) providing support for users to plan their observations; and (3) providing information on the calibration of each instrument to ensure that it is functioning properly and that the
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Portals to The Universe: The NASA Astronomy Science Centers 2 Functions of Current Science Centers The current NASA astronomy science centers provide a wide variety of services and functions, which are detailed below and in Appendix A. Overall, these functions center on the dual goals of (1) achieving optimal quality and broad dissemination of data at a reasonable cost through an effective interface between scientists, engineers, and data managers and (2) promoting public awareness of the specific mission. The centers can enable the achievement of these goals by serving specific functions. SUPPORT OF FLIGHT OPERATIONS A NASA astronomy science center serves as the link between a spacecraft and scientists on the ground. The spacecraft can be operated either by the NASA astronomy science center itself or by another entity such as a NASA field center. The NASA astronomy science center, in coordination with a distinct operations center if there is one, integrates the tasks supporting the functionality of the satellite, for example, maneuvers of the satellite in space and operation of the instruments on board, with the observations specified by the astronomer to obtain the needed scientific result. The tasks include planning and optimizing the observing schedules; transmitting the commands to the spacecraft instruments; maintaining the correct pointing of the satellite; guiding on the target; ensuring the successful transmission of data from the instruments to the ground and ultimately to the scientist; and managing target-of-opportunity programs that attempt to observe unforeseen but important transient astronomical events such as supernovae. INSTRUMENT SUPPORT AND CALIBRATION One essential function of a NASA astronomy science center is ensuring the optimum scientific performance and utilization of all instruments onboard a spacecraft and the transmission of the current state of the instrument performance to the observer. The instrument support includes (1) documenting the instrument’s performance; (2) providing support for users to plan their observations; and (3) providing information on the calibration of each instrument to ensure that it is functioning properly and that the
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Portals to The Universe: The NASA Astronomy Science Centers data are trustworthy. For imaging devices, this calibration provides information on both angular resolution and the noise levels and sensitivity of the detectors that make up the device. For spectrographs, the wavelength accuracy and sensitivity at different wavelengths must be calibrated to enable comparison with previous space and ground observations. Besides the initial calibrations from the ground and space, calibration must continue throughout the mission lifetime to follow any degradation of the instrument. The instrument support tasks are often conducted by teams of engineers and scientists. The engineers on the team provide in-depth knowledge of the instrument’s technical capabilities and devise and implement solutions to technical problems that arise. The scientists on the team reflect the viewpoint of the user community and ensure that solutions to problems will suit the users’ needs. The committee heard repeatedly in discussions with the center staff that close interaction between scientists and engineers, such as in supporting instruments and calibration, is essential to success in the development and operation of the center. Finding: Space astronomy missions are most effective when there is close interaction between scientists and engineers in the development and operation of the hardware and software to support the missions. This is especially critical for off-site principal investigator teams. NASA astronomy science centers can facilitate scientist-engineer interactions. DATA ANALYSIS (LEVEL 1 PROCESSING) For data to be useful to the community, a science center must be able to deliver useful data—that is, data that are partially processed—promptly (usually within 24 hours) to the scientist. Experts at the center must design and operate a software pipeline that starts with the raw data coming from the instrument on the satellite, corrects for the satellite movements and instrument calibrations, and produces data files, as images or tables, that the scientist can use to quickly evaluate the quality of the observation. These quick-look products can be used to detect any problems with the observation, such as instrument failure or abnormal background levels, that would require a reobservation of the target. In addition, these files are often the first step of the detailed analysis by the scientist. It is important for this data analysis functionality to be in place by the time the first information arrives from a space astronomy mission. ARCHIVING AND DISTRIBUTION TO THE COMMUNITY The NASA astronomy science center is responsible for creating the final calibrated dataset and sending it to an archive, as detailed in the specific NASA requirements for the mission. Generally, this archive must be durable, support diverse users, and allow international access. The archive adopts community-recognized and NASA-approved standards for data and services, as outlined for each mission; maintains metrics on data used and users; provides high-quality, reliable data in a timely fashion; and maintains storage devices, software, access modes, and distribution media that can evolve with the advance of technology. It supports mechanisms such as user advisory groups to receive community input and guidance and provides user services for the expert and novice. The archive typically preserves Level 0 (raw measurements), Level 1 (calibrated science data), Level 2 (data with coordinates, other information), and Level 3 (products). The final products typically include object catalogs, spectra, and images. The major archive centers currently exist at the Space Telescope Science Institute (STScI) (Multimission Archive at the Space Telescope Science Institute (MAST), for ultraviolet and optical data); at Goddard (High Energy Astrophysics Science Archive Research Center, HEASARC, for x-ray data); and at the Infrared Processing and Analysis Center (IPAC) (Infrared Science Archive, IRSA, for infrared data).
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Portals to The Universe: The NASA Astronomy Science Centers SOFTWARE DEVELOPMENT AND DOCUMENTATION FOR SCIENCE ANALYSIS Most users rely on the science center to provide the basic software programs that enable detailed analysis of their observations and those in the archive. This software development effort incorporates the expertise of the instrument developers and produces a software package that is easy to learn and that can be run on a variety of computer systems by a diverse group of users. The center provides documentation complete with worked, relevant examples of each use, taking the user from the data provided by the satellite or archive to the finished product. The software and documentation are updated as the system changes. Often these software packages perform similar functions. However, because the packages are developed by different groups for different missions, they can at times include widely divergent processes for performing similar actions. In these situations, users must spend considerable time and effort on retraining themselves. In testimony to the committee, users stressed the desirability of common software packages. Finding: The most efficient way of minimizing the effort and time spent by scientists to learn new programs is using common software across missions. HELP DESK AND OTHER USER SUPPORT Centers provide help desks to provide prompt replies to e-mail queries and, possibly, telephone support, generally during business hours on weekdays. They generally provide other online help such as tutorials and frequently asked questions so that information is available 24 hours a day, 7 days a week, especially when the help desk is closed. Researchers can also obtain user support from each other by accessing wikis1 and online discussion groups. However, for complex questions or problems dealing with software, reduction, proposal input, and observation and scheduling that are not solved elsewhere, the help desk provides the best and most up-to-date expertise. In most cases, this support eliminates the need for a user to travel to the center and enables reduction of data at the user’s institution. All NASA astronomy science centers currently maintain help desks, but the committee heard from users that the response time depends on the size of the center and the number of people at the help desk. The days leading up to a proposal deadline appear to be especially stressful for users and center staff alike. Finding: Adequate help desk staffing and online support are critical functions of centers, especially for small centers that do not have much other user support. USER WORKSHOPS AND SYMPOSIA Each new mission creates software for accessing and working with the resultant data. User workshops allow new users to learn the software system and the peculiarities of a data reduction package before working on their own at their own institutions. These workshops also provide a forum for scientists to share their experience with the software, to provide advice to the software developers, and, for those with complicated problems, to have their questions addressed in detail. Scientific symposia bring together researchers using the data, researchers thinking of applying for mission time, and the scientists at the center. These gatherings promote healthy exchanges of ideas, bring out problems and needs of the community, and identify directions for future missions. Often, they produce publications that are 1 A wiki is software that allows users to edit or change Web-based content and the organization of that content.
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Portals to The Universe: The NASA Astronomy Science Centers available to the entire community. Only the major centers generally have the resources and manpower to sponsor workshops and symposia. PROPOSAL SUBMISSION AND REVIEW All science centers provide processes for proposal input and review. To be effective, each system must contain efficient documentation on the satellite, the instrumentation, and the submission process. However, the complexity of the proposal process varies substantially from mission to mission. While past missions used the simplest formats of text and e-mail entry, most current missions now rely on form pages and uploads of PDF or postscript files. For the first-time proposer to a mission, the simplest system is often Web-based software with electronic uploads of proposal text: It works on different computer platforms, requires minimal expertise, and allows electronic submission. The most efficient use of scientists’ time is a proposal process that takes place in two phases: Phase I involves, largely, a scientific review. It is followed by a technical Phase II, which allows inputting all the details of approved observations but is required only for successful proposers. Problems can arise when software must be downloaded from a center, because many proposers do not have access to software support at their institutions if the programs do not interface easily with existing computers or security systems. Problems typically arise when the proposal software package is large, complex to use, and requires all information to be provided in only one proposal input phase. In these cases, researchers often spend months preparing a working version of the software and learning the idiosyncrasies of the satellite observations. These demands on researcher time are considerable, especially in light of proposal oversubscription rates of 5- to 10-fold on some space astronomy missions and the low rates of success for proposers. In addition, most space astronomy missions use different proposal processes, compounding the time that must be spent on any individual proposal. Examples of these different processes are the Remote Proposal System (RPS) created by HEASARC (and modified for individual missions), the Astronomer’s Proposal Tool (APT) system of STScI, and the Spitzer Planning Observation Tool (SPOT) system for Spitzer (see Box 2.1). Of these examples, RPS is the most straightforward for Phase I input; APT is used for both Phase I and Phase II, with Phase II requiring increasingly complex input; and SPOT is the most complex and time-consuming because it requires a full set of information for Phase I. Finding: A proposal entry that requires minimal technical details for the initial science proposal selection makes the fewest demands on users. The review process generally consists of several panels of experts who read and evaluate the proposals, then come to the center for face-to-face meetings to discuss and rank them. The center identifies and recruits the reviewers, coordinates the meeting, and provides expertise on any technical questions raised during the review. Since some of the best science involves multiwavelength observations crossing several missions, the efficiency of both writing and evaluating proposals is increased if proposal deadlines, formats, and reviews are coordinated. Many missions now set aside some portion of their observing time for proposals requiring coordination with other space- or ground-based facilities. GRANT ADMINISTRATION Typically, all researchers whose proposals are successful in the review process receive some funding for their research. The model that associates research funding with the allocation of observing time ensures the scientific return on a mission. Today, the science centers are responsible for reviewing and
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Portals to The Universe: The NASA Astronomy Science Centers BOX 2.1 Software for Online Proposal Submission and Review Remote Proposal System (RPS) is a Web-based multimission tool used by scientists to submit proposals for NASA missions. After information is entered, RPS generates a hard copy and the scientist verifies that the proposal information is complete prior to submission. Further information can be found at http://heasarc.gsfc.nasa.gov/rps. The Astronomer’s Proposal Tool (APT) system consists of software that is downloaded (different versions of the software exist for different types of computers) to provide tools for filling out proposal forms and calculating the orbits needed for Hubble Space Telescope data. A relatively simple version is used to input the Phase Iinitial science proposal, and an in-depth version is used to provide more details for Phase II of an accepted proposal. Further information can be found at http://www.stsci.edu/hst/proposing/apt. The Spitzer Planning and Observation Tool (SPOT) is a complex, multiplatform software tool to plan and submit an observing proposal to the Spitzer Science Center. It also involves downloading software specific to a computer platform and includes online help. Further information can be found at http://ssc.spitzer.caltech.edu/documents/spot. allocating the funds for each project, supervising the allocation of funds to coinvestigators, and dealing with the interim and final reports that are a requirement of the grant award. This administrative effort ensures the optimum and proper use of available funding. SCIENTIFIC RESEARCH The success of a mission is judged by the scientific output of its community of users as well as of the center itself. Because experience has shown that working research scientists are essential to the successful operation of astronomical observatories, each science center employs Ph.D. scientists who conduct individual research and also do some of the major work of the center. These scientists must have opportunities to conduct their own research, yet they remain primarily facilitators for the research of the outside community. Scientific research by employees of the center is an integral part of testing software and analysis tools, documenting and fixing problems, and ensuring that the mission is advertised and accessible to the entire community. Center scientists need to have current research expertise to be able to anticipate the needs of users and to provide advice. At the same time, a center must give its researchers opportunities to do their science in order to attract and retain the talent it needs. The opportunities for scientific research depend on the size of the center. The large centers—e.g., STScI, the Chandra X-ray Center, and the Spitzer Science Center—generally provide the most research time for staff. They also have highly successful fellowship programs (see Table A.1) that draw the best postdoctoral young scientists to conduct research associated with the mission either at the center or at a university. These fellows usually gather at the center each year to exchange results and ideas. Besides producing scientific results, the fellowship programs impart vital mission expertise to the outside community because the fellows can transfer their acquired knowledge of working with mission data to their colleagues. Because small missions such as the X-ray Multimirror Mission–Newton (XMM–Newton) and the Far Ultraviolet Spectroscopic
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Portals to The Universe: The NASA Astronomy Science Centers Explorer offer insufficient support for fellows (Table A.1) and center staff have less of their own time for research, a minimal amount of research time must be guaranteed to ensure the mission expertise. Each mission center operates most effectively when it ensures a balance between mission support and individual research opportunities for the staff based on the size of the operation and the size of the user community. ADVOCACY AND STRATEGIC PLANNING As the largest astronomy science centers evolve to support their user communities, they naturally become focal points, allowing astronomers to develop strategies for the immediate and long-term future of the areas of astronomy they serve. When a center convenes an annual time allocation committee for reviewing proposals, it will already have a strategy for allocating observatory time and center resources to optimize the overall scientific return. Moreover, the centers host forums in which users and center scientists plan the evolution of the observatory and the center and discuss the scientific opportunities at possible future observatories and their design parameters. Naturally these discussions, and the documents resulting from them, become inputs to strategic decisions in the community and NASA regarding the future of the field. EDUCATION AND PUBLIC OUTREACH Due to the wide public appeal of astronomy and the need to improve science education, NASA requires that all science centers support some program of education and public outreach (EPO). These include Web sites (some for the public at large and some for teachers), press releases, teacher training workshops, and EPO grants. The Web sites provide not only images and graphics specific to a mission but also show interplay between scientists and the public through programs such as Ask an Astrophysicist at HEASARC. The level of support for EPO varies with the size of the center (see Appendix A), with large centers having some staff dedicated to EPO and small centers (XMM–Newton, Rossi X-ray Timing Explorer) often sharing resources and staff with their host institutions or umbrella archive centers. Chapter 5 provides a more extensive discussion of education and public outreach activities at the science centers.