A \u27SMAD\u27 Tool for Nano and Micro Satellites

Most of the Space Mission Analysis and Design (SMAD) tools available in the industry are geared towards small and large satellites. The relationships for satellite mass, power, volume, pointing accuracy, design life versus cost available in the literature are primarily from satellite platforms 100 kg and higher, built for 3+ years mission life. Nano and microsatellites use a very different design philosophy leveraging Commercial-Off-The-Shelf (COTS) components, minimal redundancy, higher risk, have rapid development times and shorter mission durations. Here, we present a nano and microsatellite mission design tool built on a database containing about 140 earth-orbiting satellites. The database contains different subsystem component parameters based on a survey of commercially available nano and microsatellite products and a catalogue of space heritage components. Analyzed estimates of relationships between parameters such as satellite mass, volume, power, sensor, and actuator type, pointing accuracy, transmit power, data rate and cost are provided. These parameters can all be plotted against a choice variable such as cost or satellite mass. This python-based tool facilitates easy scaling of a parameter to estimate first-order calculations of satellite mass, size, power, data rate, pointing accuracy, etc., which can be used for mission concept design and systems engineering process. The visualization capability helps to create results that are clear and easy to understand. Our SMAD tool for nano/micro satellites can accelerate the design process and allows end-users to choose components based on their requirements with reduced complexity and better performance

Regional Ionosphere Mapping and Autonomous Uplink (RIMAU) Satellite Constellation for Space Weather monitoring and nowcasting over Singapore

The Regional Ionosphere Mapping and Autonomous Uplink (RIMAU) mission is a constellation of six CubeSats in an equatorial orbit, making Radio Occultation (RO) measurements of the atmosphere and in-situ Ionospheric measurements to characterize the ionosphere over equatorial South-East Asia in near real time. RIMAU builds on the success of the VELOX-CI mission developed and operated at the Satellite Research Centre (SaRC) at Nanyang Technological University, which carried a commercial-off-the-shelf GPS receiver and have been operating successfully since December 2015. RIMAU will carry GPS receivers for RO and an Ionospheric payload, the Compact Ionosphere Probe (CIP) developed by National Central University of Taiwan, consisting of a planar Langmuir probe, retarding potential analyser and Ion trap/drift meter. RIMAU-1 is scheduled to be in operation by 2021 with the full constellation scheduled for flight by 2023. A secondary objective of RIMAU is to provide a Low Earth Orbiting nanosatellite platform for communication with remote sensors in the region. RIMAU-1 will demonstrate communication with remote water sensors monitoring water pollutants and uplink from ground based GPS sensors to adjust the sampling rate for the Ionospheric probe during periods of high scintillation. Understanding the occurrence and impact of Ionospheric irregularities is critically needed for equatorial countries like Singapore. In this paper, we present a novel idea to combine ground based and space based Ionospheric observations to monitor in near-real time the Ionosphere over the Singapore region to characterize Ionospheric disturbances and their impact on communication and navigation systems. The main data products from these measurements will be vertical profiles of the Total Electron Content (TEC) in the ionosphere, atmospheric temperature and humidity profiles in the troposphere. RIMAU TEC measurements will be combined with ground based TEC measurements from ~ 60 GPS receivers in the SE Asia region, operated by the Earth Observatory of Singapore to produce 3D maps of the Ionosphere

Regional Ionosphere Mapping and Autonomous Uplink (RIMAU) Satellite Constellation for Space Weather monitoring and nowcasting over Singapore

The Regional Ionosphere Mapping and Autonomous Uplink (RIMAU) mission is a constellation of six CubeSats in an equatorial orbit, making Radio Occultation (RO) measurements of the atmosphere and in-situ Ionospheric measurements to characterize the ionosphere over equatorial South-East Asia in near real time. RIMAU builds on the success of the VELOX-CI mission developed and operated at the Satellite Research Centre (SaRC) at Nanyang Technological University, which carried a commercial-off-the-shelf GPS receiver and have been operating successfully since December 2015. RIMAU will carry GPS receivers for RO and an Ionospheric payload, the Compact Ionosphere Probe (CIP) developed by National Central University of Taiwan, consisting of a planar Langmuir probe, retarding potential analyser and Ion trap/drift meter. RIMAU-1 is scheduled to be in operation by 2021 with the full constellation scheduled for flight by 2023. A secondary objective of RIMAU is to provide a Low Earth Orbiting nanosatellite platform for communication with remote sensors in the region. RIMAU-1 will demonstrate communication with remote water sensors monitoring water pollutants and uplink from ground based GPS sensors to adjust the sampling rate for the Ionospheric probe during periods of high scintillation. Understanding the occurrence and impact of Ionospheric irregularities is critically needed for equatorial countries like Singapore. In this paper, we present a novel idea to combine ground based and space based Ionospheric observations to monitor in near-real time the Ionosphere over the Singapore region to characterize Ionospheric disturbances and their impact on communication and navigation systems. The main data products from these measurements will be vertical profiles of the Total Electron Content (TEC) in the ionosphere, atmospheric temperature and humidity profiles in the troposphere. RIMAU TEC measurements will be combined with ground based TEC measurements from ~ 60 GPS receivers in the SE Asia region, operated by the Earth Observatory of Singapore to produce 3D maps of the Ionosphere

Design and Development of a PS4-OP Payload for Solar Spectral Irradiance Measurements and Technology Demonstration of Small-Satellite Subsystems

This article describes the design and development of INSPIRE-0, a payload on the spent stage of the ISROs PSLV. Recently, the Indian Space Research Organisation (ISRO) released an announcement of opportunity inviting proposals to develop payloads that can be tested on the PS4-Orbital Platform (PS4-OP). This platform is a novel idea formulated by ISRO to use the spent fourth/final stage of the Polar Satellite Launch Vehicle (PSLV), called the PS4, to conduct in-orbit scientific experiments and technology demonstration of small-satellite subsystems. INSPIRE-0 is a PS4-OP payload, jointly developed by the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado Boulder, the Indian Institute of Space Science and Technology (IIST), and the Nanyang Technological University (NTU) in Singapore. This payload has two main objectives. Firstly, the scientific objective is to characterize the solar spectrum using a novel sensor, developed by NTU, that has a wide frequency range from visible to near the infra-red region. The specific objective of the INSPIRE-0 payload is to demonstrate that accurate Solar Spectral Irradiance (SSI) continuous measurements are possible using new compact and robust disruptive technologies. A successful demonstration will pave the way for a future constellation of CubeSats that will provide a very cost-effective way to monitor the Total Solar Irradiance and SSI of the sun in the various spectral bands. Secondly, the INSPIRE-0 payload aims to flight qualify the in-house developed subsystems for the INSPIRESat-1 small satellite mission, namely, the Command and Data Handling (C&DH) Subsystem and the Electrical Power Subsystem (EPS). The article first describes the systems architecture of the payload which has a size of 15cm x 10cm x 7.5 cm, a mass of 1kg, and power consumption of 1.75 W. This is followed by the details of the science instrument and an overview of the different subsystems, namely the C&DH, the EPS, and the PS4-OP interface board. The article concludes with the details of the testing, including comprehensive performance tests and environmental tests, performed to prepare the payload for a planned launch on the PS4-OP in the third quarter of 2021

Development of a Power-Efficient, Low Cost, and Flash FPGA Based On-Board Computer for Small-Satellites

On-Board Computers (OBCs) for Small-satellite missions are typically required to be designed using industrial grade Commercial-of-the-shelf (COTS) components due to budget constraints and short mission duration. The OBC must provide a variety of interfaces due to the diverse nature of COTS subsystems having different interface definitions. Traditional OBC designs with standard microcontrollers have fixed interfaces that require modification of the motherboard circuit/layout when the external interfaces require changes. Thus, a possible solution is to have an FPGA in-addition to the micro-controller thereby providing a configurable interface capability. System-on-Chip (SoC) devices that integrate a microcontroller with FPGA fabric provide an ideal solution for reducing the development time. Additionally, the limited availability of power in small satellite missions makes it essential to use power-efficient devices. Furthermore, single event upsets (SEUs) and single event latch-up (SELs) are a major problem for OBCs designed for Low Earth Orbit (LEO) small-satellite missions. Flash memory-based FPGAs provide the benefit of low power consumption and they are more also fault-tolerant due to their intrinsic robustness against induced single event upsets compared to SRAM-based FPGAs. This article describes the OBC developed using the flash-based Microsemi SmartFusion2 SoC FPGA as its key component, for the INSPIRESat-1 and INSPIRESat-2 small-satellite missions. The OBC is designed in two form factors one with 13cm x 10cm dimensions for INSPIRESat-1 and the other with 10cm x 10cm dimensions for INSPIRESat-2. The OBC uses a COTS System-on-Module (SoM) developed by Emcraft containing the SmartFusion2 SoC, which is mounted on a custom-designed motherboard containing other peripherals including flash memory, SD Cards, and an external watchdog timer. The OBC has a total power consumption of approximately 1 W, in the final flight configuration. The article here describes the architecture of the OBC in detail, the key features of which include multiple on-board memories, a multi-level reset methodology, and reconfigurable input/output interfaces. The article concludes with the details of comprehensive performance tests conducted on the INSPIRESat-1 OBC, which has qualified TRL-8 (technology readiness level) status after completing required environmental tests such as the Thermal Vacuum Test (TVAC) and vibration test as a part of the integrated satellite. INSPIRESat-2 was launched in January 2021 and due to the successful working of the OBC in fight it has achieved TRL-9 status through this mission. The OBC developed for INSPIRESat-1 is planned to achieve TRL-9 status after its launch in the third quarter of 2021

MEDDB: A medicinal plant database developed with the information gathered from tribal people in and around Madurai, Tamil Nadu

Tribal peoples are endowed with enriched traditional wisdom to use available nature resources around them. They are well versed in the usage of plant for treating various diseases. They have used powder or extract or paste form of the plant parts such as root, shoot, whole plant, fruits and leaves etc. The recipe known by the tribal people was passed on only to their family members and community through mouth to mouth practice. Hence, the knowledge is confined to particular people alone. It is always expedient to store information in the database, so that it will be accessible by everyone from everywhere. To achieve this, MEDDB has been developed, which stores the details of 110 plant species that are commonly used by tribes for fever, asthma, cold, cough, diabetes, diarrhea, dysentery, eye infections, stomach ache, wounds and snake bite. The details of each plant were collected from the literature and through web search to give comprehensive and exhaustive information. Each plant entry is compiled under the subheadings viz., common name, classification, physical characteristics, medicinal uses, active constituents, and references

Southern Hemisphere Summer Mesopause Responses to El Niño-Southern Oscillation

In the Southern Hemisphere (SH) polar region, satellite observations reveal a significant upper-mesosphere cooling and a lower-thermosphere warming during warm ENSO events in December. An opposite pattern is observed in the tropical mesopause region. The observed upper-mesosphere cooling agrees with a climate model simulation. Analysis of the simulation suggests that enhanced planetary wave (PW) dissipation in the Northern Hemisphere (NH) high-latitude stratosphere during El Nino strengthens the Brewer-Dobson circulation and cools the equatorial stratosphere. This increases the magnitude of the SH stratosphere meridional temperature gradient and thus causes the anomalous stratospheric easterly zonal wind and early breakdown of the SH stratospheric polar vortex. The resulting perturbation to gravity wave (GW) filtering causes anomalous SH mesospheric eastward GW forcing and polar upwelling and cooling. In addition, constructive inference of ENSO and quasi-biennial oscillation (QBO) could lead to stronger stratospheric easterly zonal wind anomalies at the SH high latitudes in November and December and early breakdown of the SH stratospheric polar vortex during warm ENSO events in the easterly QBO phase (defined by the equatorial zonal wind at similar to 25 hPa). This would in turn cause much more SH mesospheric eastward GW forcing and much colder polar temperatures, and hence it would induce an early onset time of SH summer polar mesospheric clouds (PMCs). The opposite mechanism occurs during cold ENSO events in the westerly QBO phase. This implies that ENSO together with QBO could significantly modulate the breakdown time of SH stratospheric polar vortex and the onset time of SH PMC

INSPIRESat-1: A Year of On-Orbit Operations

INSPIRESat-1 (IS-1) was the first mission under the INternational Satellite Program In Research and Education (INSPIRE) program, a consortium of universities coming together to space science missions. IS-1 launched on February 14, 2022 at 00:30 UTC to a sun synchronous dawn-dusk orbit onboard the Indian Space Research Organization\u27s PSLV C52 mission. The IS-1 spacecraft was primarily developed at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado with significant contributions from the Indian Institute of Space Science and Technology (IIST), NCU of Taiwan and Nanyang Technological University (NTU) in Singapore. The IS-1 carries two scientific instruments: The Compact Ionospheric Probe (CIP) developed at National Central University (NCU) for studying Earth\u27s dynamic ionosphere and the NASA funded Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) developed at LASP for studying the highly-variable solar X-ray radiation. DAXSS is a follow on from the highly successful MinXSS 1 &2 missions. First contact was established with the spacecraft 45 minutes after launch. The first science instruments were turned on by February 27th. DAXSS has now observed multiple solar flares in the current increasing phase of solar cycle 25 for a period of 16 months. In this paper we will present details on spacecraft performance in a unique dawn dusk orbit which presents thermal challenges not encountered frequently by nano-satellite platforms. We also present preliminary science results from CIP and DAXSS instruments from a year of on-orbit operations. Operations of the Spacecraft has also been unique with multiple universities commanding and downlinking science data

The AEPEX Mission: Imaging Energetic Particle Precipitation Into Earth’s Upper Atmosphere

Radiation belt electron fluxes can be enhanced during geomagnetic storms by two orders of magnitude; subsequently, these fluxes decay back to nominal levels in a few days. Precipitation into the upper atmosphere is a primary loss mechanism for these electrons, particularly during the decay phase. Upon impacting the upper atmosphere, these electrons create new ionization, leading to a chemical response that increases NOx and HOx and destroys ozone. Quantifying both radiation belt loss and the impact on the atmosphere requires an accurate estimate of the flux, energy spectrum, and spatial and temporal scales of precipitation. The NASA-funded Atmospheric Effects of Precipitation through Energetic X-rays (AEPEX) Cube-Sat mission is designed to quantify these parameters of radiation belt precipitation by measuring the bremsstrahlung X-rays created during the precipitation process, using a new instrument called the Atmospheric X-ray Imaging Spectrometer (AXIS). Hard X-rays (50-300 keV) emitted by Earth’s atmosphere have previously been measured from high-altitude balloons and satellites, but have never been imaged from space. The AXIS instrument will image the X-ray fluxes produced by the atmosphere, providing measurements of spatial scales, along with the X-ray flux and spectrum, using off-the-shelf pixelated detector modules and coded aperture optics. A solid-state energetic particle detector, with heritage from the FIREBIRD Cube Sat mission, will measure the precipitating electron energy spectrum, which is used to constrain the inversion from X-ray fluxes to electron fluxes. The AEPEX spacecraft is a 6U CubeSat, currently being built by the University of Colorado Boulder. It includes a custom-designed structure and a custom spacecraft bus consisting of an electrical power system, command and data handling, flight software, and instrument interface electronics designed by the Laboratory for Atmospheric and Space Physics (LASP) at CU Boulder. The system also includes custom-designed doubly-deployable solar panels. The mission will be launched into ahigh-inclination orbit to ensure coverage of high latitudes; launch is scheduled for early 2024