The formation control testbed

SPIE Proceedings, 2004

The Coronagraph version of the Terrestrial Planet Finder (TPF) mission relies on a large-optics, space-born observatory, which requires extreme stability of the optics in the presence of thermal and dynamic disturbances. The structural design requires balancing of stringent constraints on launch packaging with unusually tight response requirements for thermal and dynamic environments. The minimum-mission structural model (pre-phase A, point design) includes a deployable, pre-tensioned membrane, sun-shield and solar-sail, a 1Om long deployable secondary support structure, and a light-weighted 6m diameter monolithic glass primary mirror. We performed thermal distortion and dynamic response analyses in order to demonstrate feasibility, quantify critical sensitivities, and to identify potential problems that might need to be addressed early on.

Modeling and Systems Engineering for Astronomy, 2004

The Kepler mission will launch in 2007 and determine the distribution of earth-size planets (0.5 to 10 earth masses) in the habitable zones (HZs) of solar-like stars. The mission will monitor > 100,000 dwarf stars simultaneously for at least 4 years. Precision differential photometry will be used to detect the periodic signals of transiting planets. Kepler will also support asteroseismology by measuring the pressure-mode (p-mode) oscillations of selected stars. Key mission elements include a spacecraft bus and 0.95meter, wide-field, CCD-based photometer injected into an earth-trailing heliocentric orbit by a 3-stage Delta I1 launch vehicle as well as a distributed Ground Segment and Follow-up Observing Program. The project is currently preparing for Preliminary Design Review (October 2004) and is proceeding with detailed design and procurement of long-lead components. In order to meet the unprecedented photometric precision requirement and to ensure a statistically significant result, the Kepler mission involves technical challenges in the areas of photometric noise and systematic error reduction, stability, and false-positive rejection. Programmatic and logistical challenges include the collaborative design, modeling, integration, test, and operation of a geographic/all d functionally distributed project. A very rigorous systems engineering program has evolved to address these chall+geS his paper provides an overview of the ----requirements synthesis, validation & verification, system robustness design, and end-to-end performance modeling.

Publications of the Astronomical Society of the Pacific, 2010

We present a framework for the analysis of direct detection planet finding missions using space telescopes. This framework generates simulations of complete missions, with varying populations of planets, to produce ensembles of mission simulations, which are used to calculate distributions of mission science yields. We describe the components of a mission simulation, including the complete description of an arbitrary planetary system, the description of a planet finding instrument, and the modeling of a target system observation. These components are coupled with a decision modeling algorithm, which allows us to automatically generate mission timelines with simple mission rules that lead to an optimized science yield. Along with the details of our implementation of this algorithm, we discuss validation techniques and possible future refinements. We apply this analysis technique to four mission concepts whose common element is a 4m diameter telescope aperture: an internal pupil mapping coronagraph with two different inner working angles, an external occulter, and the THEIA XPC multiple distance occulter. The focus of this study is to determine the ability of each of these designs to achieve one of their most difficult mission goals -the detection and characterization of Earth-like planets in the habitable zone. We find that all four designs are capable of detecting on the order of 5 Earth-like planets within a 5 year mission, even if we assume that only 1 out of every 10 stars has such a planet. The designs do differ significantly in their ability to characterize the planets they find. Along with science yield, we also analyze fuel usage for the two occulter designs, and discuss the strengths and weaknesses of each of the mission concepts.

2004

Abstract: The Terrestrial Planet Finder formation flying Interferometer (TPF-I) will be a five-spacecraft, precision formation operating near a Sun-Earth Lagrange point. As part of technology development for TPF-I, a formation and attitude control system (FACS) is being ...

Techniques and Instrumentation for Detection of Exoplanets IV, 2009

We use our automated Design Reference Mission construction framework to evaluate the performance of multiple direct exoplanet imager mission concepts on a variety of metrics including: total number of planetary detections, number of unique planets found, number of target stars observed and number of successful spectral characterizations. We evaluate designs of self-contained coronagraphs and co-orbiting occulters. Performance is evaluated on simulated universes with differing frequencies of planets and varying expected occurrence rates of different planet types. Use: http://spiedl.org/terms † The same size starshade is required for both the 1 and 4m telescopes because the smaller telescope aperture spreads the point spread function, requiring a relatively larger level of suppression to produce the required contrast at the same IWA.

2009

The exploration of Earth-like exoplanets will be enabled at mid-infrared wavelengths through technology and engineering advances in nulling interferometry and precision formation flying. Nulling interferometry provides the dynamic range needed for the detection of biomarkers. Formation flying provides the angular resolution required in the mid-infrared to separately distinguish the spectra of planets in multi-planet systems. The flight performance requirements for nulling have been met and must now be validated in a flight-like environment. Formation-flying algorithms have been demonstrated in the lab and must now be validated in space. Our proposed technology program is described.

2000

Prior to discovery of extrasolar planets, the overwhelming majority of planetary research focused on explaining the properties of our own Solar System, sometimes in considerable detail. The discovery of extrasolar planetary systems revealed an unexpected diversity of planetary systems that has revolutionized planet formation theory. A strong program of theoretical research is essential to maximize both the discovery potential and the scientific returns of future observational programs, so as to achieve a deeper understanding of the formation and evolution of planetary systems. We outline three broad categories of theoretical research. Detailed studies of specific planetary systems can provide insights into the planet formation process ( §2.1). This approach is particularly effective for multiple planet systems with strong dynamical constraints (e.g., high precision radial velocity (RV) and/or astrometric measurements). Second, theorists can test planet formation models by comparing their predictions to the observed exoplanet population ( §2.2). This approach benefits greatly from wide planet surveys sensitive to a broad range of planets and stars. Finally, detailed modeling of specific physical processes is essential to understand planet formation and the origin of our solar system ( §2.3). Dynamical research plays an important role in analyzing observations for a wide range detection methods ( §3) and contributes to understanding the Earth's place in the universe and the potential for Earth-like life beyond our solar system ( §4). In this white paper, we suggest how to maximize the scientific return of future exoplanet observations ( §5).

SPIE Proceedings, 2016

The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to ∼ 100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.

Modeling and Systems Engineering for Astronomy, 2004

Because of the complexity of the Terrestrial Planet Finder (TPF) design concepts, the project will rely heavily on the use of engineering and science simulations to predict on-orbit performance. Furthermore, current understanding of these missions indicates that the 3m to 8m class optical systems need to be as stable as picometers in wavefront and sub-milli arcsec in pointing. These extremely small requirements impose on the models a level of predictive accuracy heretofore never achieved, especially in the area of microgravity effects, material property accuracy, thermal solution convergence, and all other second order modeling effects typically ignored. New modeling tools and analysis paradigms are developed which emphasize computational accuracy and %lly integrated analytical simulations. The process is demonstrated on sample problems using the TPF Coronagraph design concept. The TPF project is also planning a suite of testbeds through which various aspects of the models and simulations will be verified.

UV/Optical/IR Space Telescopes: Innovative Technologies and Concepts III, 2007

The concept of flying an occulting shade in formation with an orbiting space telescope to enable astronomical imaging of faint targets while blocking out background noise primarily from starlight near distant Earth-like planets has been studied in various forms over the past decade. Recent analysis has shown that this approach may offer comparable performance to that provided by a space-based coronagraph with reduced engineering and technological challenges as well as overall mission and development costs. This paper will present a design of the formation flying architecture (FFA) for such a collection system that has potential to meet the scientific requirements of the National Aeronautics and Space Administration's (NASA's) Terrestrial Planet Finder mission. The elements of the FFA include the relative navigation, intersatellite communication, formation control, and the spacecraft guidance, navigation, and control (GN&C) systems. The relative navigation system consists of the sensors and algorithms to provide necessary range, bearing or line-of-sight, and relative attitude between the telescope and occulter. Various sensor and filtering (estimation) approaches will be introduced. A formation control and GN&C approach will be defined that provides the proper alignment and range between the spacecraft, occulter, and target to meet scientific objectives. The state of technology will be defined and related to several formation flying and rendezvous spacecraft demonstration missions that have flown.