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The Committee on Space Research (COSPAR) in 2020 established a new Task Group to develop an "actionable" plan for an international constellation of small satellites. COSPAR will play the role of an honest broker in assembling an international consortium that will develop, launch, and acquire data from a constellation of small satellites contributed from voluntary participants. The COSPAR team, known formally as the Task Group on establishing a Constellation of Small Satellites (TGCSS), identified space weather monitoring from a constellation of LEO small satellites as one of its primary objectives from the constellation. TGCSS will facilitate development of mission concepts, constellation architecture, coordinate launch opportunities, as well as reference payloads and supporting ground facilities. The preliminary scientific objectives focus on measuring plasma conditions in the ionosphere, and atmospheric drag with sufficient measurement density to substantially improve space weather forecasts. In this presentation, we will report on the presently defined mission objectives and constellation design, as well as plans on implementation. It is hoped that through collaboration with the scientific community, the COSPAR constellation will help to address pertinent scientific objectives, while also serving as a platform for capacity building and international collaboration.

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.

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.

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.

The Ionospheric Dynamics and Attitude Subsystem Satellite (IDEASSat) is a 3U CubeSat carrying a Compact Ionospheric Probe (CIP) to detect ionospheric irregularities that can impact the usability and accuracy of global satellite navigation systems (GNSS), as well as satellite and terrestrial over the horizon communications. The spacecraft was developed by National Central University (NCU) in Taiwan, with additional development and operational support from partners in the International Satellite Program in Science and Education (INSPIRE) consortium. The spacecraft system needed to accommodate these mission objectives required three axis attitude control, dual band communications capable of supporting both tracking, telemetry and command (TT&C) and science data downlink, as well as flight software and ground systems capable of supporting the autonomous operation and short contact times inherent to a low Earth orbit mission developed on a limited university budget with funding agency-imposed constraints. As the first spacecraft developed at NCU, lessons learned during the development, integration, and operation of IDEASSat have proven to be crucial to the objective of developing a sustainable small satellite program. IDEASSat was launched successfully on January 24, 2021 aboard the SpaceX Falcon 9 Transporter 1 flight. and successfully began operations, demonstrating power, thermal, and structural margins, as well as validation of uplink and downlink communications functionality, and autonomous operation. A serious anomaly occurred after 22 days on orbit when communication with the spacecraft were abruptly lost. Communication was re-established after 1.5 months for sufficient time to downlink stored flight data, which allowed the cause of the blackout to be identified to a high level of confidence and precision. In this paper, we will report on experiences and anomalies encountered during the final flight model integration and delivery, commissioning, and operations. The agile support from the international amateur radio community and INSPIRE partners were extremely helpful in this process, especially during the initial commissioning phase following launch. It is hoped that the lessons learned reported here will be helpful for other university teams working to develop spaceflight capacity.

The Satellite Research Centre at Nanyang Technological University is currently developing the Atmospheric Coupling and Dynamics Explorer (ARCADE) Mission, which is flying a hall effect thruster to progressively lower the altitude from an initial 500 km to 250 km. ARCADE is also the fourth satellite in the INSPIRE (International Satellite Program in Research and Education) satellite series with joint development from IIST, India and NCU, Taiwan. ARCADE is a 27U spacecraft carrying an ionospheric plasma payload which will make ion temperature, velocity, density and electron temperature measurements. The satellite will be launched along with six other Singaporean satellites on a Singapore dedicated PSLV in 2020 into a near equatorial orbit. Since the final altitude is expected to be 250 km, the ARCADE/INSPIRESat-4 mission provides an excellent opportunity to study the equatorial ionosphere at low altitudes where the ion and electron density are much higher. The mission is expected to provide new information on plasma irregularities along the magnetic equator. The mission is also a technology demonstration of a hall effect thruster developed by French Startup 'Thrust Me'. Another addition to the mission is a Spatial Heterodyne Interferometer Infra-Red Imager for imaging the Mesosphere and Lower thermosphere region between 60-120 km. The SHI instrument will provide temperature information and help for understanding the dynamics of the equatorial MLT region. The presentation will cover the teams approaches to dealing with Very Low Earth Orbit (VLEO) and the challenges it poses in terms of thermal and atomic oxygen effects.

The International Satellite Program in Research and Education’s (INSPIRE) first satellite is an Ionosphere and Solar X-ray observing microsat slated for launch in November of 2019 onboard an ISRO Polar Satellite Launch Vehicle. The microsat has a mission specific structure fitting on a PSLV ring deployer. There are two payloads aboard with two different science objectives. The Compact Ionosphere Probe (CIP) will take in-situ measurements of ion density, composition, temperature, velocity, and electron temperature. The CIP is a smaller version of the Advanced Ionosphere Probe (AIP, both developed in Taiwan) currently operating onboard the FORMOSat-5. This instrument is capable of sampling the ionosphere at 1 and 8 Hz. The second payload is the Dual Aperture X-ray Solar spectrometer (DAXSS). DAXSS is a modified Amptek X123 that will observe Solar X-rays, specifically soft X-rays. Hot plasma in the sun’s corona is best measured in the soft X-rays. Many emission lines for important elements (Fe, Si, Mg, S, etc) are in the soft X-ray range. Soft X-rays are always present in the sun but 100 times brighter during flares, these observations will also lend to understanding the temperature difference between the sun’s corona and photosphere. The solar soft x-rays are also important for the Earth’s Ionosphere, adding to the ionosphere observations made by CIP. The DAXSS instrument has heritage from a NASA calibration rocket experiment and two cubesats, MINXSS 1 and 2. The newer model Amptek X123 has much improved energy resolution for the X-ray spectrum. The primary science objectives of the INSPIRESat-1 are twofold. First, enabling the characterization of the temporal and spatial distributions of small-scale plasma irregularities like plasma bubbles and the Midnight Temperature Maximum (MTM) in season, location, and time by CIP. Second, giving a greater understanding of why the Sun’s corona is orders of magnitude hotter than the photosphere, why there is an abundance of elements change during different solar events, and how these events (observed with greater soft x-ray fidelity) effect the earth’s ionosphere. In this paper, we present science expectations for the INSPIRESat-1 and a concept for coordinated Ionospheric measurements covering several altitudes and local times using three satellite platforms carrying the same CIP instrument (INSPIRESat-1, IDEASat/INSPIRESat-2, INSPIRESat-4, FORMOSat-5). We describe the development of DAXSS and how the dual aperture prevents the need for two X123 to get the similar data. We also highlight the unique development of the INSPIRESat-1 microsat being developed by international collaboration across three different universities.

CubeSats are becoming an increasingly important and viable platform for space physics observations, in addition to their longstanding role in education and technology demonstration. With proper mission formulation, design, and testing, CubeSats have the potential to extend the capability of observations from large satellite missions. The Ionosphere Dynamics Explorer and Attitude Subsystem Satellite (IDEASSat / INSPIRESat-2) is a 3U CubeSat mission funded in part by the Taiwan National Space Organization (NSPO) and executed by Taiwan National Central University (NCU) in conjunction with international partners as part of the International Satellite Program in Research and Education (INSPIRE) consortium. The science payload is the Compact Ionospheric Probe (CIP): an all in one insitu plasma sensor combining retarding potential analyzer, ion trap, ion drift meter, and planar Langmuir probe modes in a time-sharing manner, providing measurements of ion density, temperature, composition, and drift velocity, as well as electron temperature. CIP traces its heritage to the Advanced Ionospheric Probe (AIP) launched and currently operational onboard the FORMOSAT-5 satellite since August 2017. With both spacecraft operational in high inclination Sun synchronous orbits following the expected IDEASSat launch in 2020, comprehensive in-situ measurements of ionospheric variability and irregularities can be obtained to understand their effects on radio communications and satellite navigation signals.

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.

The International Satellite Program in Research and Education’s (INSPIRE) first satellite is an ionosphere exploring microsat slated for launch in November of 2019 onboard an ISRO Polar Satellite Launch Vehicle. The microsat is a custom designed structure fitting on a PSLV ring deployer. The payload is the Compact Ionosphere Probe (CIP) which will take in-situ measurements of ion density, composition, temperature, velocity, and electron temperature. The CIP is a smaller version of the Advanced Ionosphere Probe (both developed in Taiwan) currently operating onboard the FORMOSAT-5. These instruments take measurements in four modes sampling the ionosphere at 1 or 8 Hz. The primary science objectives of the INSPIRESat-1 are twofold. First, enabling a greater understanding of the temporal and spatial distributions of small-scale plasma irregularities like plasma bubbles and second a characterization of the Midnight Temperature Maximum (MTM) in season, location, and time. In this paper, we present science expectations for the INSPIRESat-1 and consider the potential for coordinated measurements between three platforms carrying the same instrument (INSPIRESat-1, IDEASat/INSPIRESat-2, FORMOSAT-5). We also highlight the program management strategy used by the INSPIRE program in developing an internationally developed microsat.

Five concentric atmospheric gravity wave (AGW) events have been identified in Polar Mesospheric Cloud (PMC) images of the summer mesopause region (~82–84 km) made by the Cloud Imaging and Particle Size (CIPS) instrument on board the Aeronomy of Ice in the Mesosphere satellite during the Northern Hemisphere 2007 and 2009 PMC seasons. The AGWs modulate the PMC albedo, ice water content, and particle size, creating concentric ring patterns. On only one occasion (13 July 2007), the concentric AGWs in PMCs were aligned with AGWs with similar shapes observed in 4.3 µm radiance in the lower stratosphere, as measured by Atmospheric Infrared Sounder (AIRS). Coincident AIRS and Infrared Atmospheric Sounding Interferometer nadir measurements of 8.1 µm radiance reveal a region of deep convection in the troposphere close to the estimated centers of the AGWs in the stratosphere, strongly suggesting that convection is the wave source. The AGWs in CIPS on 13 July 2007 were ~1000 km away from the observed deep convection. Three other concentric AGWs in PMCs were 500–1000 km away from deep convection in the troposphere, while no convection was observed related to the wave on 29 July 2009. We perform a 2-D ray tracing study for the AGW event on 13 July 2007. The calculated propagation distance is much shorter than the distance between the AGWs in PMCs and the observed convection. The 2-D ray tracing study indicates that the AGWs in PMCs and in the stratosphere are probably excited by different tropospheric convective systems.

Major stratospheric sudden warmings (SSW) occurring during Northern Hemisphere winter were identified in four runs of the Whole Atmosphere Community Climate Model (WACCM). Their characteristics are compared to those found by other authors using reanalysis data. The comparison shows that the frequency of occurrence of major SSW in the model is very similar to that found in reanalysis data, as is the occurrence of vortex splitting and displacement events. The main difference with respect to observations is that the modeled SSW are relatively longer lasting. WACCM simulates quite accurately some dynamical features associated with major SSW, despite the presence of outlier cases; however, the recently reported relationship between regional blocking and the type of SSW is only partially reproduced by WACCM. In general, the observed climatological and dynamical signatures of displacement SSW tend to be better reproduced by the model than those associated with splitting SSW. We also find that SSW in the model are often associated with an elevated polar cap stratopause, in agreement with recent observations. However, the simulations also show that there is not in general a close correspondence between major SSW and elevated polar cap stratopause events.

Major stratospheric sudden warmings (SSW) occurring during Northern Hemisphere winter were identified in four runs of the Whole Atmosphere Community Climate Model (WACCM). Their characteristics are compared to those found by other authors using reanalysis data. The comparison shows that the frequency of occurrence of major SSW in the model is very similar to that found in reanalysis data, as is the occurrence of vortex splitting and displacement events. The main difference with respect to observations is that the modeled SSW are relatively longer lasting. WACCM simulates quite accurately some dynamical features associated with major SSW, despite the presence of outlier cases; however, the recently reported relationship between regional blocking and the type of SSW is only partially reproduced by WACCM. In general, the observed climatological and dynamical signatures of displacement SSW tend to be better reproduced by the model than those associated with splitting SSW. We also find that SSW in the model are often associated with an elevated polar cap stratopause, in agreement with recent observations. However, the simulations also show that there is not in general a close correspondence between major SSW and elevated polar cap stratopause events.