Papers by Giuseppe Cataldo
Space robotics has enabled tremendous discoveries in planetary sciences and has emerged as an inc... more Space robotics has enabled tremendous discoveries in planetary sciences and has emerged as an incubator of technologies with major impacts on the quality of life for the Earth's growing population and with important commercial potential. The purpose of this research is to develop new paradigms for space robotics, such as quick construction, less expensive components that can be used for different types of robots, and improved user operability, and to determine how robots and humans can best interact in order to add value to human-robotics space missions. The mission-oriented approach adopted in this context consists of the investigation of several lunar exploration scenarios with the purpose of analyzing the appropriate task distribution among humans and robots. Presented in this work is a mission concept study of a lunar far-side radio observatory optimized to observe the neutral 21-cm emission from the intergalactic medium during the dark ages of cosmic structure formation and the early stages of cosmic reionization. The Self-Tending Array Node and Communication Element (STANCE) model is the concept being investigated, which combines four helices into a single interferometer element (stance) with more than 5000 stances deployed in a relatively flat area at least 10 km across on the far side of the Moon. The discussion will illustrate the scientific requirements as well as the technical requirements which they drive. Details will be provided about the elements under study, such as array configuration, deployment, site selection, power systems and thermal management, data transport and transmission to Earth. Finally, the role of astronauts and robots in the implementation of this observatory and its operations will be shown to have an impact on the design of such a complex mission, and it will be seen how this interaction poses further constraints to the different subsystems in terms of mass, power, size, and cost.
Acta Astronautica, 2015
The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view... more The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Micro-Spec (µ-Spec), a high-efficiency direct-detection spectrometer concept working in the 450-1000-µm wavelength range, will enable a wide range of spaceflight missions that would otherwise be challenging due to the large size of current instruments and the required spectral resolution and sensitivity. This paper focuses on the µ-Spec two-dimensional multimode region, where the light of different wavelengths diffracts and converges onto a set of detectors.
Review of Scientific Instruments, 2015
A method is proposed and experimentally explored for in-situ calibration of complex transmission ... more A method is proposed and experimentally explored for in-situ calibration of complex transmission data for superconducting microwave resonators. This cryogenic calibration method accounts for the instrumental transmission response between the vector network analyzer reference plane and the device calibration plane. Once calibrated, the observed resonator response is analyzed in detail by two approaches. The first, a phenomenological model based on physically realizable rational functions, enables the extraction of multiple resonance frequencies and widths for coupled resonators without explicit specification of the circuit network. In the second, an ABCD-matrix representation for the distributed transmission line circuit is used to model the observed response from the characteristic impedance and propagation constant. When used in conjunction with electromagnetic simulations, the kinetic inductance fraction can be determined with this method with an accuracy of 2%. Datasets for superconducting microstrip and coplanar-waveguide resonator devices were investigated and a recovery within 1% of the observed complex transmission amplitude was achieved with both analysis approaches. The experimental configuration used in microwave characterization of the devices and self-consistent constraints for the electromagnetic constitutive relations for parameter extraction are also presented.
Micro-Spec (µ-Spec) is a high-sensitivity direct-detection spectrometer operating in the farinfra... more Micro-Spec (µ-Spec) is a high-sensitivity direct-detection spectrometer operating in the farinfrared and submillimeter regime. When combined with a cryogenic telescope, it provides an enabling technology for studying the epoch of reionization and initial galaxy formation. As a direct-detection spectrometer, µ-Spec can provide high sensitivity under the low background conditions provided by cryogenic telescopes such as the space infrared telescope for cosmology and astrophysics SPICA. The µ-Spec modules use low-loss superconducting microstrip transmission lines implemented on a single 4-inch-diameter wafer. Such a dramatic size reduction is enabled by the use of silicon, a material with an index of refraction about three times that of vacuum, which thus allows the microstrip lines to be one third their vacuum length. Using a large number of modules as well as reducing the negative effects of stray light also contributes positively to the enhanced sensitivity of such an instrument. µ-Spec can be compared to a grating spectrometer, in which the phase retardation generated by the reflection from the grating grooves is instead produced by propagation through transmission lines of different length. The µ-Spec optical design is based on the stigmatization and minimization of the light path function in a two-dimensional diffractive region. The power collected through a broadband antenna is progressively divided by binary microstrip power dividers. The position of the radiators is selected to provide zero phase errors at two stigmatic points, and a third stigmatic point is generated by introducing a differential phase shift in each radiator. To optimize the overall efficiency of the instrument, the emitters are directed to the center of the focal surface. A point design was developed for initial demonstration. Because of losses to other diffraction orders, the efficiency of the design presented is about 30%. Design variations on this implementation are illustrated which can lead to near-unit efficiency and will be the basis of future instruments. Measurements are being conducted to validate the designs.
Micro-Spec (µ-Spec) is a high-performance spectrometer working in the 250-700-µm wavelength range... more Micro-Spec (µ-Spec) is a high-performance spectrometer working in the 250-700-µm wavelength range, whose modules use low-loss superconducting microstrip transmission lines on a single 4-inch-diameter silicon wafer. Creating the required phase delays in transmission lines rather than free space allows such an instrument to have, in principle, the performance of a meter-scale grating spectrometer. Such a dramatic size reduction enables classes of instruments for space that would be impossible with conventional technologies. This technology can dramatically enhance the long-wavelength capability of the space infrared telescope for cosmology and astrophysics SPICA. µ-Spec is analogous to a grating spectrometer. The phase retardation generated by the reflection from the grating grooves is instead produced by propagation through a transmission line. The power received by a broadband antenna is progressively divided by binary microstrip power dividers, and the required phase delays are generated by different lengths of microstrip transmission lines. By arranging these outputs along a circular focal surface, the analog of a Rowland spectrometer can be created. The procedure to optimize the Micro-Spec design is based on the stigmatization and minimization of the light path function in a two-dimensional bounded region, which results in an optimized geometry arrangement with three stigmatic points. In addition, in order to optimize the overall efficiency of the instrument, the emitters are directed to the center of the focal surface. The electric field amplitude and phase as well as the power transmitted and absorbed throughout the region are analyzed. Measurements are planned in late summer to validate the designs.
Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, 2014
The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view... more The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Our ability to fully explore this rich spectral region has been limited, however, by the size and cost of the cryogenic spectrometers required to carry out such measurements. Micro-Spec (µ-Spec) is a high-sensitivity, direct-detection spectrometer concept working in the 450-1000 µm wavelength range which will enable a wide range of flight missions that would otherwise be challenging due to the large size of current instruments with the required spectral resolution and sensitivity. The spectrometer design utilizes two internal antenna arrays, one for transmitting and one for receiving, superconducting microstrip transmission lines for power division and phase delay, and an array of microwave kinetic inductance detectors (MKIDs) to achieve these goals. The instrument will be integrated on a ∼ 10 cm 2 silicon chip and can therefore become an important capability under the low background conditions accessible via space and high-altitude borne platforms. In this paper, an optical design methodology for µ-Spec is presented, with particular attention given to its two-dimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the maximization of the instrument resolving power and minimization of the RMS phase error on the instrument focal plane. This two-step optimization can generate geometrical configurations given specific requirements on spectrometer size, operating spectral range and performance. Two point designs with resolving power of 260 and 520 and an RMS phase error less than ∼ 0.004 radians were developed for initial demonstration and will be the basis of future instruments with resolving power up to about 1200.
The Astrophysical Journal, 2013
The Optical Properties of Astronomical Silicates with Infrared Techniques program utilizes multip... more The Optical Properties of Astronomical Silicates with Infrared Techniques program utilizes multiple instruments to provide spectral data over a wide range of temperatures and wavelengths. Experimental methods include Vector Network Analyzer and Fourier transform spectroscopy transmission, and reflection/scattering measurements. From this data, we can determine the optical parameters for the index of refraction, n, and the absorption coefficient, k. The analysis of the laboratory transmittance data for each sample type is based upon different mathematical models, which are applied to each data set according to their degree of coherence. Presented here are results from iron silicate dust grain analogs, in several sample preparations and at temperatures ranging from 5 to 300 K, across the infrared and millimeter portion of the spectrum (from 2.5 to 10,000 µm or 4000 to 1 cm −1 ).
Optics Letters, 2012
Silicon nitride thin films play an important role in the realization of sensors, filters, and hig... more Silicon nitride thin films play an important role in the realization of sensors, filters, and high-performance circuits. Estimates of the dielectric function in the far-and mid-infrared regime are derived from the observed transmittance spectra for a commonly employed low-stress silicon nitride formulation. The experimental, modeling, and numerical methods used to extract the dielectric parameters with an accuracy of approximately 4% are presented.
Applied Optics, 2011
Dust is found throughout the universe and plays an important role for a wide range of astrophysic... more Dust is found throughout the universe and plays an important role for a wide range of astrophysical phenomena. In recent years, new IR facilities have provided powerful new data for understanding these phenomena. However, interpretation of these data is often complicated by a lack of complementary information about the optical properties of astronomically relevant materials. The Optical Properties of Astronomical Silicates with Infrared Techniques (OPASI-T) program at NASA's Goddard Space Flight Center is designed to provide new high-quality laboratory data from which we can derive the optical properties of astrophysical dust analogues. This program makes use of multiple instruments, including new equipment designed and built specifically for this purpose. The suite of instruments allows us to derive optical properties over a wide wavelength range, from the near-IR through the millimeter, also providing the capability for exploring how these properties depend upon the temperature of the sample. In this paper, we discuss the overall structure of the research program, describe the new instruments that have been developed to meet the science goals, and demonstrate the efficacy of these tools.
Applied Optics, 2014
High-performance, integrated spectrometers operating in the far-infrared and sub-millimeter promi... more High-performance, integrated spectrometers operating in the far-infrared and sub-millimeter promise to be powerful tools for the exploration of the epochs of reionization and initial galaxy formation. These devices, using high-efficiency superconducting transmission lines, can achieve the performance of a meter-scale grating spectrometer in an instrument implemented on a four-inch silicon wafer. Such a device, when combined with a cryogenic telescope in space, provides an enabling capability for studies of the early universe. Here, the optical design process for Micro-Spec (µ-Spec) is presented, with particular attention given to its two-dimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the stigmatization and minimization of the light path function in this bounded region, which results in an optimized geometrical configuration. A point design with an efficiency of ∼ 90% has been developed for initial demonstration, and can serve as the basis for future instruments. Design variations on this implementation are also discussed, which can lead to lower efficiencies due to diffractive losses in the multimode region.
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation For Astronomy V, 2010
ABSTRACT Astronomical dust is observed in a variety of astrophysical environments and plays an im... more ABSTRACT Astronomical dust is observed in a variety of astrophysical environments and plays an important role in radiative processes and chemical evolution in the galaxy. Depending upon the environment, dust can be either carbon-rich or oxygen-rich (silicate grains). Both astronomical observations and ground-based data show that the optical properties of silicates can change dramatically with the crystallinity of the material, and recent laboratory research provides evidence that the optical properties of silicate dust vary as a function of temperature as well. Therefore, correct interpretation of a vast array of astronomical data relies on the understanding of the properties of silicate dust as functions of wavelength, temperature, and crystallinity. The OPASI-T (Optical Properties of Astronomical Silicates with Infrared Techniques) project addresses the need for high quality optical characterization of metal-enriched silicate condensates using a variety of techniques. A combination of both new and established experiments are used to measure the extinction, reflection, and emission properties of amorphous silicates across the infrared (near infrared to millimeter wavelengths), providing a comprehensive data set characterizing the optical parameters of dust samples. We present room temperature measurements and the experimental apparatus to be used to investigate and characterize additional metal-silicate materials.
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Papers by Giuseppe Cataldo