EChO Payload electronics architecture and SW design

EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer, covering the wavelength range from 0.55 $\mu$m, to 11.0 $\mu$m. The baseline design includes the goal wavelength extension to 0.4 $\mu$m while an optional LWIR module extends the range to the goal wavelength of 16.0 $\mu$m. An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem interfacing the spacecraft and collecting data from all the payload spectrometers modules. ICU is in charge of two main tasks: the overall payload control (Instrument Control Function) and the housekeepings and scientific data digital processing (Data Processing Function), including the lossless compression prior to store the science data to the Solid State Mass Memory of the Spacecraft. These two main tasks are accomplished thanks to the Payload On Board Software (P-OBSW) running on the ICU CPUs.Comment: Experimental Astronomy - EChO Special Issue 201

Adaptability of a Catalog Spacecraft Bus to Diverse Science Missions

Over the past decade, the concept of using “offthe- shelf” Spacecraft (SC) buses for space science and earth science missions has become widespread. A “common bus” design approach has been used for Geosynchronous (GEO) communications satellites since the early 1970’s. The success of using common bus designs for the manufacture of GEO communications satellites is due to the commonality of mission requirements and orbit geometry. Science missions, on the other hand, each have unique mission and instrument payload requirements that can vary widely, encompassing orbit geometry, instrument type and configuration, science target, SC attitude, operations concept, and launch scenario. One of the most visible and successful implementations of “off-the-shelf” SC for science applications is the NASA Goddard Space Flight Center (GSFC) Rapid Spacecraft Development Office (RSDO) catalog, first released in 1997. In the current catalog (Rapid II), there are twenty-three different SC buses manufactured by eight aerospace companies. This paper provides a case study describing the adaptation of Spectrum Astro’s SA-200HP (High Performance) RSDO catalog SC bus to two very different Low Earth Orbiting (LEO) science missions, Coriolis and Swift, which were both procured via the RSDO. Coriolis is a Department-of-Defense-sponsored sunsynchronous earth observation satellite whose primary instrument, WindSat, is designed to precisely measure the ocean surface wind vector. Swift is a low inclination NASA Medium Explorer (MIDEX) mission to detect and characterize Gamma Ray Bursts (GRBs). The Swift Observatory carries three separate telescopes. In addition to describing how the catalog SC bus was applied to these missions, this paper discusses the unique features and benefits of the catalog bus approach to both the procuring agency and the industry bus provider. Misconceptions associated with the use of the catalog bus approach are also discussed

AXTAR: Mission Design Concept

The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling, and an ability to respond promptly to time-critical targets of opportunity. It is optimized for submillisecond timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star surfaces and black hole event horizons, thus probing the physics of ultradense matter, strongly curved spacetimes, and intense magnetic fields. AXTAR's main instrument, the Large Area Timing Array (LATA) is a collimated instrument with 2-50 keV coverage and over 3 square meters effective area. The LATA is made up of an array of supermodules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for AXTAR and present results from a preliminary mission design study.Comment: 19 pages, 10 figures, to be published in Space Telescopes and Instrumentation 2010: Ultraviolet to Gamma Ray, Proceedings of SPIE Volume 773

Titan Explorer: The Next Step in the Exploration of a Mysterious World

The Titan Explorer Mission outlined in this report is a proposed next step in the exploration of Titan, following the highly successful Huygens Titan probe of 2005. The proposed Titan Explorer Mission consists of an Orbiter and an Airship that traverses the atmosphere of Titan and can land on its surface. The Titan Explorer Mission is science driven and addresses some of the fundamental questions about the atmosphere, surface and evolution of Titan, which will add to our understanding of the origin and evolution of life on Earth and assess the likelihood of life elsewhere in the Solar System

WITTEX: A Constellation of Three Small Satellite Radar Altimeters

WITTEX, named in honor of E. Witte, who in 1878 first discovered the geostrophic current equation, is an acronym for Water Inclination Topography and Technology Experiment. WITTEX consists of three co-planar small satellite radar altimeters launched on the same vehicle into a GEOSAT -class orbit. The proposed satellite constellation would support measurement for the first time of both orthogonal components of the ocean\u27s surface slope, rather than the single component seen by conventional instruments. The satellites are spaced by several kilometers along their orbit; Earth rotation causes their sub-satellite tracks to be laterally separated. Track separation can be readily adjusted by selection and autonomous control of inter-satellite spacing. If the satellite spacing were about 900 km, then the sub-satellite orbit tracks would fall approximately uniformly 53 km apart at the equator. This spacing is nearly optimal for observing oceanic eddy fields and surface energy transport. The enabling conceptual innovation is the delay-Doppler radar altimeter (DDA). Studies have shown that this technique yields more precise measurements than a conventional radar altimeter, yet it requires much less transmitted power. The notional instrument has two frequencies and an onboard water vapor radiometer, similar to TOPEX. The DDA approach, combined with recent advances in spacecraft technology, leads to substantial miniaturization; the goal is to use Pegasus as the launch vehicle. The enabling technologies include the Integrated Electronics Module (IEM), chip-on-board (COB), and the Command and Data Handling In-YourPalm (CDHIYP), all developed at The Johns Hopkins University Applied Physics Laboratory (JHU/APL). The WITTEX concept is a flexible, capable, unique, and cost-effective approach that will significantly advance the state of the art in both technical and scientific arenas

Cryogenic Propellant Storage and Transfer Technology Demonstration: Prephase A Government Point-of-Departure Concept Study

The primary purpose of this study was to define a point-of-departure prephase A mission concept for the cryogenic propellant storage and transfer technology demonstration mission to be conducted by the NASA Office of the Chief Technologist (OCT). The mission concept includes identification of the cryogenic propellant management technologies to be demonstrated, definition of a representative mission timeline, and definition of a viable flight system design concept. The resulting mission concept will serve as a point of departure for evaluating alternative mission concepts and synthesizing the results of industry- defined mission concepts developed under the OCT contracted studie

EChO payload electronics architecture and SW design

EChO is a three-modules (VNIR, SWIR, MWIR), highly integrated spectrometer, covering the wavelength range from 0.55 μ m to 11.0 μ m. The baseline design includes the goal wavelength extension to 0.4 μ m while an optional LWIR module extends the range to the goal wavelength of 16.0 μ m. An Instrument Control Unit (ICU) is foreseen as the main electronic subsystem interfacing the spacecraft and collecting data from all the payload spectrometers modules. ICU is in charge of two main tasks: the overall payload control ( Instrument Control Function) and the housekeepings and scientific data digital processing ( Data Processing Function), including the lossless compression prior to store the science data to the Solid State Mass Memory of the Spacecraft. These two main tasks are accomplished thanks to the Payload On Board Software (P-OBSW) running on the ICU CPUs. <P /