Through an innovative public-private partnership, a new generation of high-fidelity imaging spectrometers has been designed for the detection and measurement of methane (CH4) and carbon dioxide (CO2) plumes from super-emitters to help improve accounting and enable reduction of greenhouse gases in the Earth’s atmosphere. Two identical instruments, built concurrently at NASA Jet Propulsion Laboratory (referred to by JPL as the Carbon Plume Mapper project “CPM”) and Planet Labs as part of the Carbon Mapper Coalition, will measure the spectral range of 400 – 2500 nm with a spectral sampling of 5.0 nm. The identical optical design comprises a three-mirror anastigmat (TMA) telescope and Dyson form spectrometer which reduces volume and mass for a fast (F/1.8) optical system. The instruments will be integrated into Planet-built Tanager satellites and launched into low-Earth orbit (LEO). This work describes the assembly and alignment of the two identical instruments. At the subsystem level, both instruments follow the same procedure. For telescope alignment, the mirrors are first coarsely aligned with a coordinate measuring machine (CMM) and then finely aligned in a double-pass interferometer setup. The spectrometer subsystem is aligned onaxis using a commercial lens alignment instrument for precise, non-contact measurements. The telescope and spectrometer alignment results and performance are presented and compared. At the system level, the procedures deviate due to the separate and unique optical ground support equipment (OGSE) configurations utilized by JPL and Planet to implement the same instrument design. Both end-to-end optical alignment configurations are discussed, and the final CPM performance is shown with a focus on the five key and driving imaging spectrometer performance requirements.
Through an innovative public-private partnership, a new generation of high-fidelity hyperspectral imaging spectrometers has been designed to pinpoint, quantify, and track methane (CH4) and carbon dioxide (CO2) point-source emissions from super-emitters to help enable reduction of greenhouse gases in the Earth’s atmosphere. Two identical instruments, built concurrently at NASA Jet Propulsion Laboratory (referred to by JPL as the Carbon Plume Mapper project, CPM) and Planet Labs as part of the Carbon Mapper Coalition, feature an identical design which comprises a glass-ceramic, three-mirror anastigmat (TMA) telescope, held in place via a composite metering structure, and Dyson form spectrometer which reduces volume and mass for a fast (F/1.8) optical system. The telescope has a focal length and cross-track field of view (FOV) of 400 mm and 2.6 deg, respectively. Operating in the 400 – 2500 nm spectral range with 5.0 nm sampling, this spectrometer design has the sensitivity and resolution required to meet the demanding needs of space-based detection and quantification of CO2 and CH4 emissions. This work describes the instruments’ optomechanical configuration.
The Carbon Plume Mapper (CPM) instrument is a high-fidelity imaging spectrometer developed to pinpoint, quantify, and track methane (CH4) and carbon dioxide (CO2) point source emissions to help enable reduction of greenhouse gases in the Earth’s atmosphere. CPM will operate over the spectral range of 400 – 2500 nm with a spectral sampling of 5.0 nm. CPM will be integrated into an industry partner spacecraft bus and launched into low-Earth orbit (LEO). The optical design comprises a three-mirror anastigmat (TMA) telescope and Dyson form spectrometer which reduces volume and mass for a fast (F/1.8) optical system. An overview of the CPM optical design, development, and current status is discussed.
Starting in 2023, the Carbon Mapper public-private partnership will launch two imaging spectrometers into low earth orbit as the first demonstration satellites for a larger, emerging constellation. This mission is a critical collaboration between several partners including Planet, Carbon Mapper, Arizona State University, NASA’s Jet Propulsion Laboratory, the University of Arizona, the High Tide Foundation, California Air Resources Board, and the Rocky Mountain Institute. This hyperspectral constellation will complement Planet’s existing high-spatial and high-temporal mission lines and increase the ability to measure and monitor the impacts of climate change on our planet and tackle dynamic, wide-ranging and complex challenges such as sustainability. Each satellite is equipped with a 400 - 2500 nm hyperspectral imaging system capable of addressing a wide range of applications. The core mission for the Carbon Mapper Mission is to monitor climate risks (methane, CO2) but it has capacity to collect data for other sectors such as Defense, Intelligence, Agriculture, Mining, and others. The Carbon Mapper Mission is a tasked system and is designed to be responsive to dynamic events where analysis in a matter of days or hours may be important. In this paper, we provide an overview of the anticipated technical capabilities of the system and discuss applications for the Defense and Intelligence communities. We will also outline how the Carbon Mapper Mission can work in conjunction with the rest of the Planet constellations to enable unique fusion products.
KEYWORDS: Planets, Stars, Signal to noise ratio, Planetary systems, Signal detection, Exoplanets, Space operations, Systems modeling, Charge-coupled devices, Observatories
The Kepler mission was a National Aeronautics and Space Agency (NASA) Discovery-class mission designed to continuously monitor the brightness of at least 100,000 stars to determine the frequency of Earth-size and larger planets orbiting other stars. Once the Kepler proposal was chosen for a flight opportunity, it was necessary to optimize the design to accomplish the ambitious goals specified in the proposal and still stay within the available resources. To maximize the science return from the mission, a merit function (MF) was constructed that relates the science value (as determined by the PI and the Science Team) to the chosen mission characteristics and to models of the planetary and stellar systems. This MF served several purposes; predicting possible science results of the proposed mission, evaluating the effects of varying the values of the mission parameters to increase the science return or to reduce the mission costs, and supporting quantitative risk assessments. The MF was also valuable for the purposes of advocating the mission by illustrating its expected capability. During later stages of implementation, it was used to keep management informed of the changing mission capability and support rapid design tradeoffs when mission down-sizing was necessary. The MF consisted of models of the stellar environment, assumed exoplanet characteristics and distributions, detection sensitivity to key design parameters, and equations that related the science value to the predicted number and distributions of detected exoplanet. A description of the MF model and representative results are presented. Examples of sensitivity analyses that supported design decisions and risk assessments are provided to illustrate the potential broader utility of this approach to other complex science-driven space missions.
KEYWORDS: Stars, Planets, Space operations, Photometry, Charge-coupled devices, Data centers, System on a chip, Aerospace engineering, Space telescopes, Signal to noise ratio
The Kepler Mission is a search for terrestrial planets specifically designed to detect Earth-size planets in the habitable zones of solar-like stars. In addition, the mission has a broad detection capability for a wide range of planetary sizes, planetary orbits and spectral types of stars. The mission is in the midst of the developmental phase with good progress leading to the preliminary design review later this year. Long lead procurements are well under way. An overview in all areas is presented including both the flight system (photometer and spacecraft) and the ground system. Launch is on target for 2007 on a Delta II.
KEYWORDS: Systems engineering, Stars, Performance modeling, Space operations, Photometry, Signal to noise ratio, Data modeling, Data acquisition, Planets, Error analysis
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 II 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 geographically and functionally distributed project. A very rigorous systems engineering program has evolved to address these challenge. This paper provides an overview of the Kepler systems engineering program, including some examples of our processes and techniques in areas such as requirements synthesis, validation & verification, system robustness design, and end-to-end performance modeling.
The StarLight flight project was designed to demonstrate the key technologies of spaceborne long-baseline stellar interferometry and precision formation flying for potential use on the Terrestrial Planet Finder (TPF) and other future astrophysics missions. Interferometer performance validation could be achieved over a 6-12 month period by obtaining several hundred fringe visibility amplitude measurements for stars in the band 600-1000 nm for a variety of stellar visibilities, magnitudes, and baselines. Interferometery could be performed both in a 1 meter fixed-baseline combiner-only mode and in a two-spacecraft formation mode. In formation mode, the combiner spacecraft would remain at the focus of a virtual parabola, while the collector spacecraft assumed various positions along the parabola such that the two arms of the interferometer remained equal over a variety of separations and bearing angles. Challenges to be encountered in flight include high-bandwidth inter-spacecraft stellar and metrology pointing control, alingment and shear correction, delay and delay-rate estimation, visibility calibration, and robust fringe trackign in the presence of local and inter-spacecraft dynamics. This paper is based on the StarLight project design-capture of March 2002 and will describe the StarLight Interferometer System architecture and selected operational concepts.
The StarLight mission is designed to validate the technologies of formation flying and stellar interferometry in space. The mission consists of two spacecraft in an earth-trailing orbit that formation-fly over relative ranges of 40 to 600m to an accuracy of 10 cm. The relative range and bearing of the spacecraft is sensed by a novel RF sensor, the Autonomous Formation Flyer sensor, which provides 2cm and 1mrad range and bearing knowledge between the spacecraft. The spacecraft each host instrument payloads for a Michelson interferometer that exploit the moving spacecraft to generate variable observing baselines between 30 and 125m. The StarLight preliminary design has shown that a formation-flying interferometer involves significant coupling between the major system elements - spacecraft, formation-flying control, formation-flying sensor, and the interferometer instrument. Mission requirements drive innovative approaches for long-range heterodyne metrology, optical design, glint suppression, formation estimation and control, spacecraft design, and mission operation. Experimental results are described for new technology development areas.
The Shuttle Radar Topography Mission (SRTM), scheduled for an 11 day Space Shuttle flight in 1999, will use an Interferometric Synthetic Aperture Radar instrument to produce a near-global digital elevation map of the earth's land surface with 16 m absolute vertical height accuracy at 30 meter postings. SRTM will achieve the required interferometric baseline by extending a receive-only radar antenna on a 60 meter deployable mast from the shuttle payload bay. Continuous measurement of the interferometric baseline length, attitude, and position is required at the 2 mm, 9 arcsec, and 1 m levels, respectively, in order to obtain the desired height accuracy. The attitude and orbit determination avionics (AODA) subsystem will provide these functions for SRTM. The AODA flight sensor complement includes electro-optical metrology sensor, a star tracker, an inertial reference unit, GPS receivers, plus supporting electronics and computers. AODA ground processing computers will support SRTM system performance evaluation during the mission and baseline reconstruction after the mission. The final AODA data products will be combined with the radar data to reconstruct the height information necessary for topographic map generation. A description of the AODA system architecture, error budgets, and the major issues involved with measuring large space structures are presented.
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