KazSTSAT (Kazak Science and Technology Satellite)
SSTL (Surrey Satellite Technology Ltd.) of Guildford, UK and Ghalam LLP of Astana, Kazakhstan have agreed that SSTL's new X50 platform design will deliver KazSTSAT, a small collaborative satellite mission announced under a contract signed in July 2013.
Ghalam LLP is a joint venture between JSC "National Company Kazakhstan Garysh Sapary" (KGS) and EADS Astrium. Under the contract, SSTL and the Ghalam team will jointly develop the "SSTL-X50" platform using heritage SSTL platform design and payload equipment including an SSTL EarthMapper payload designed for global commercial wide-area imaging, as well as flying a number of jointly-developed equipments and payloads, a novel imaging instrument, and a new on-board computer. The new platform will be designed to provide over 50 W orbit average power to a 50 kg payload mission and it is intended that the platform and some of the new technologies will be used on future Kazak missions. 1) 2) 3)
Under a joint development program, 14 Kazakh engineers will work alongside SSTL engineers to design and build the KazSTSAT spacecraft. In addition to the SLIM-6 imager, KazSTSAT will fly a number of Ghalam LLP developed payloads, and will join the Disaster Monitoring Constellation (DMC), which provides daily images for applications including global disaster monitoring. Environmental testing will take place at a new Ghalam LLP test facility being established in Astana, Kazakhstan.
The KazSTSAT mission is a collaboration between Ghalam LLP of Kazakhstan, SSTL, and UK based DMCii, an image processing company. In April 2015, the UKSA (UK Space Agency) announced some funding support through the IPSP ( International Partnerships Space Program) to aid in the development of an autonomous and collaborative Mission Operations system in partnership with Ghalam LLP to handle the high volume of Earth observation data that will be downloaded from the spacecraft's SSTL SLIM6 Imager, enabling the full research and commercial data provision of the mission to be realized. 4)
Some background: 5)
Over the last three decades, SSTL have delivered over 40 small satellites for a range of applications including Earth Observation, Communications, Navigation, Science and Technology Demonstration. Schedule, price and reliability are very important factors for all customers, and increasingly commercial spacecraft operators are considering groups of satellites working as part of a constellation. SSTL has been involved with a number of such constellations in various capacities, including DMC (Disaster Monitoring Constellation), RapidEye, Kanopus, FormoSat-7/COSMIC2 at spacecraft level, and at payload / subsystem level in ORBCOMM-SG, CYGNUS and the 22 Galileo FOC payloads. The production philosophy typically adopted for such batches of satellites to consider the closest existing product, modify this to the specific mission needs, build a proto flight unit, and then carry out a limited batch production run. As a result, the cost savings that can be achieved in batch production are often limited, as the base design was never optimized for such a batch production.
For individual spacecraft, the cost of the spacecraft production can also be prohibitive for science and technology demonstration missions, or restrict the feasibility of new business ideas in space. Increasingly, the labor costs involved in spacecraft production are dominating. SSTL has developed a concept for spacecraft manufacture which has so far not been used elsewhere in the space industry, which removes some of these limitations and cost drivers. This is targeted at improving production cost, speeding up mission delivery, and maintaining and improving reliability.
Figure 1 shows the SSTL missions and their respective launch dates. Because many of the same subsystems are used on several different spacecraft busses and mission, there is regular and significant opportunity in SSTL to batch build spacecraft equipments and so make economy of scale cost savings - even across different spacecraft for different customers, providing they are produced at roughly the same time. There are then also some cost savings in sharing staff and facilities. For instance, in the AIT/EVT (Assembly, Integration and Test/Environmental Test) phase, spacecraft can be processed at around the same time using the same test setup, for instance sharing a Thermal Vacuum chamber. For most missions, SSTL already gains these benefits. Nevertheless there is a fundamental limit on the amount of savings that can be achieved without a significant investment in building equipment for stock and permanent test setups, due to the fact that the avionics were designed considering conventional 20th century space industry practices, namely handcrafted production, human inspection, one-off and bespoke setup and test, and manual harness integration.
Figure 1: SSTL historical parallel spacecraft production (image credit: SSTL)
In order to provide further significant improvements in price and schedule for constellations of spacecraft, as well as on individual satellites, it is necessary to consider alternative approaches. An SSTL internal R&D program was started in 2011, with its main objective to improve performance to cost ratios even further, by exploiting new commercially developed technologies, protocols and processes in order to offer improved performance of current SSTL small satellite platforms at a similar or lower mass, but with significantly reduced schedule and price. This internal development program heavily leverages the investment made in other industries in batch manufacture of highly reliable products, and has resulted in the "X-Series" spacecraft.
The SSTL-X50 series of spacecraft are the first mission products. The series were released in 2013, and the first spacecraft using this class bus is already under contract and in production. Initially implemented on a high performance 50 kg class platform, the SSTL X50, the X-series core architecture and avionics will be implemented in all SSTL's small platforms over the next three to five years, thereby lowering the cost and improving delivery times for all X-series platforms.
SSTL has developed the new SSTL-X50 satellite platform to provide a smaller, lighter, flexible spacecraft with enhanced systems capabilities and quality. With a mass range of 50 -100 kg, the compact, highly integrated design baselines flight-proven heritage with next-generation "Fireworks" avionics to incorporate fully dual redundant subsystems and scaled core platform services such as power, structure, data processing, communications and high-precision attitude control. 6)
Figure 2: Two views of the KazSTSAT microsatellite with the EarthMapper payload (image credit: SSTL)
A block diagram of the SSTL-X50 ‘EarthMapper' configuration is shown in Figure 3, compared with a block diagram for a more complex X-series spacecraft configuration. The 'Card Frame' based architecture at the heart of all of the X-Series platforms has been developed with maximum flexibility and modularity in mind. A number of standard building block "cards" deliver the main platform functions such as power conditioning, TT&C, on-board processing and storage. The card-frame can be configured in an expandable arrangement to deliver the platform performance required by different payloads and associated mission classes. The ADCS (Attitude Determination and Control Subsystem) provides arcsecond attitude knowledge from star cameras, data storage of a minimum of 256 GB (Ref. 5).
Figure 3: System block diagrams (configurable common building blocks) for simple SSTL-X50 microsatellites (left) and more complex X-series spacecraft (right) like the SSTL-X300-S1 minisatellite series (image credit: SSTL)
Figure 4: Enlarged block diagram of the KazSTSAT-X50 platform (image credit: SSTL) 7)
The new platform design allows SSTL to take advantage of automated batch avionics manufacturing and test processes, and aids rapid assembly and integration of the spacecraft, bringing customers the benefit of shorter order to orbit timescales and reduced fixed-price costs.
The expected advantages of the new platform compared to similar heritage platforms include:
• Larger on-board payload data storage capacity
• Several orders of magnitude more powerful OBC that may potentially be used for heavy on-board processing of the payload data, as well as for some advanced star tracker and GPS functionalities
• Higher supported payload mass
• Higher orbit average power available to the payload.
Different size platforms can employ the new avionics mostly through duplication of modules to increase storage, computer and power capability. The first of these to be realized is KazSTSAT for Ghalam LLP, which is an "SSTL-X50" - 50 kg class platform.
KazSTSAT will be based on the SSTL-X50 EarthMapper variant and will carry an SSTL SLIM-6 imager, providing 17.5 m resolution multispectral imagery on a swath width of ~600 km for global wide-area imaging.
RF communications: The S-band is used for TT&C transmissions. X-band downlink for payload data transmission at 80 Mbit/s, onboard data storage capacity of 256 GB. Data compression ratio: Lossless up to 2.5:1, lossy 4:1 or higher. S-band is used for TT&C.
Table 1: Specification of the KazSTSAT microsatellite
Status of the KazSTSAT development:
• The payload data system was delivered for the KazSTSAT mission in November 2015. Spacemetric (Spacemetric Ltd., Farnborough, UK, a subsidiary of Spacemetric AB, Sollentuna, Sweden) has delivered a Keystone System for the KazSTSAT mission being developed jointly by SSTL and Ghalam LLC of Kazakhstan. The SSTL SLIM6 sensor has been modified for the KazSTSAT mission to specifications defined by DMC International Imaging Ltd (DMCii), the commercial distributor of imagery from the DMC satellites. This medium-resolution imager now provides Coastal Blue, Blue and Red-Edge channels in addition to the Red, Green and NIR (Near Infrared) channels of the previous DMC missions. Spacemetric is responsible for physical sensor modelling of the new instrument and has incorporated this capability into the Keystone software. After launch, the sensor parameters will be refined through an in-orbit calibration. 8)
• Start of AIT in August 2015.
• CDR (Critical Design Review) in May 2015.
• The end of Phase C in April 2015.
Launch: The KazSTSAT microsatellite was part of the SSO-A rideshare mission of Spaceflight (total of 64 satellites) launched on 3 December 2018 (18:34:05 GMT) on a SpaceX Falcon-9 Block 5 vehicle from VAFB (Vandenberg Air Force Base) in California. 9) 10) 11) 12)
SpaceX statement: On Monday, December 3rd at 10:34 a.m. PST (18:34 GMT), SpaceX successfully launched Spaceflight SSO-A: SmallSat Express to a low Earth orbit from Space Launch Complex 4E (SLC-4E) at Vandenberg Air Force Base, California. Carrying 64 payloads, this mission represented the largest single rideshare mission from a U.S.-based launch vehicle to date. A series of six deployments occurred approximately 13 to 43 minutes after liftoff, after which Spaceflight began to command its own deployment sequences. Spaceflight's deployments are expected to occur over a period of six hours. 13)
This mission also served as the first time SpaceX launched the same booster a third time. Falcon 9's first stage for the Spaceflight SSO-A: SmallSat Express mission previously supported the Bangabandhu Satellite-1 mission in May 2018 and the Merah Putih mission in August 2018. Following stage separation, SpaceX landed Falcon 9's first stage on the "Just Read the Instructions" droneship, which was stationed in the Pacific Ocean.
Orbit: Sun-synchronous circular orbit with an altitude of 575 km, inclination of ~98º, LTDN (Local Time of Descending Node) of 10:30 hours.
Figure 5: KazSTSAT with Ghalam-SSTL launch team (image credit Spaceflight Industries)
List of payloads on the Spaceflight SSO-A rideshare mission
The layout of the list follows the alphabetical order of missions as presented on the Wikipedia page "2018 in spaceflight" https://en.wikipedia.org/wiki/2018_in_spaceflight#November — as well as with the help of Gunter Krebs's short descriptions at https://space.skyrocket.de/doc_lau_det/falcon-9_v1-2.htm / https://space.skyrocket.de/doc_sdat/skysat-3.htm
Note: this payload list has to be revised.
• AISTechSat, a 6U CubeSat for Earth observation of AISTech (Access to Intelligent Space Technologies), Barcelona, Spain.
• Al Farabi-2, a CubeSat technology demonstration mission of the Al-Farabi Kazakh National University, Kazakhstan.
• Astrocast, a 3U CubeSat technology demonstration mission of Astrocast, Switzerland, dedicated to the Internet of Things (IoT)
• Audacy Zero, a 3U CubeSat technology demonstration mission of Audacy, Mountain View, CA
• BeeSat-5 to -8 (Berlin Experimental and Educational Satellite) of TU Berlin, a picosatellite mission consisting of four 0.25 CubeSats.
• BlackSky-2, a microsatellite (55 kg) of BlackSky Global which will provide 1 m resolution imagery with improved geolocation accuracy.
• BRIO, a 3U CubeSat of SpaceQuest Ltd. of Fairfax, VA to test a novel communications protocol that uses SDR (Software Defined Radio).
• Capella-1, a microsatellite (37 kg) of Capella Space, San Francisco, CA featuring a X-band SAR (Synthetic Aperture) payload.
• Centauri-2, a 3U CubeSat of Fleet Space Technologies, Adelaide, South Australia. Demonstration of IoT technologies.
• COPPER (Close Orbiting Propellant Plume and Elemental Recognition) CubeSat of Saint Luis University, Saint Louis, MO, USA.
• CSIM-FD (Compact Spectral Irradiance Monitor-Flight Demonstration), a 6U CubeSat of LASP (Laboratory for Atmospheric and Space Physics) at the University of Boulder, CO, USA. The goal is to measure solar spectral irradiance to understand how solar variability impacts the Earth's climate and to validate climate model sensitivity to spectrally varying solar forcing.
• Eaglet-1, the first 3U CubeSat of OHB Italia SpA for Earth Observation.
• Elysium Star-2, a 1U CubeSat of Elysium Space providing space burial services.
• ESEO (European Student Earth Orbiter) sponsored by ESA, a microsatellite of ~40 kg with 6 instruments aboard.
• Eu:CROPIS (Euglena and Combined Regenerative Organic-Food Production in Space), a minisatellite (230 kg) of DLR, Germany. The objective is to study food production in space in support of future long-duration manned space missions (life sciences). The main payloads are two greenhouses, each maintained as a pressurized closed loop system, simulating the environmental conditions of the Moon or of Mars.
• eXCITe (eXperiment for Cellular Integration Technology), a DARPA (Defense Advanced Research Projects Agency) mission to demonstrate the 'satlets' technology. Satlets are a new low-cost, modular satellite architecture that can scale almost infinitely. Satlets are small modules that incorporate multiple essential satellite functions and share data, power and thermal management capabilities. Satlets physically aggregate in different combinations that would provide capabilities to accomplish diverse missions.
• ExseedSat-1, a 1U CubeSat mission by the Indian company Exseed Space. The goal is to provide a multifunction UHF/VHF NBFM (Narrow Band Frequency Modulation) amateur communication satellite.
• FalconSat-6, a minisatellite (181 kg) of the USAFA (U.S. Air Force Academy) and sponsored by AFRL. FalconSat-6 hosts a suite of five payloads to address key AFSPC (Air Force Space Command) needs: SSA (Space Situational Awareness) and the need to mature pervasive technologies such as propulsion, solar arrays, and low power communications.
• Flock-3, three 3U CubeSats of Planet Labs to provide Earth observation.
• Fox-1C, a radio amateur and technology research 1U CubeSat developed by AMSAT and hosting several university developed payloads.
• Hawk, a formation-flying cluster of three microsatellites (13.4 kg each) of HawkEye 360, Herndon, VA, USA. The goal is to demonstrate high-precision RFI (Radio Frequency Interference) geolocation technology monitoring.
• Hiber-2 is 6U CubeSat pathfinder mission of Hiber Global, Noordwijk, The Netherlands, for Hiber Global's planned (IoT) communications CubeSat constellation.
• ICE-Cap (Integrated Communications Extension Capability), a 3U CubeSat of the US Navy. The objectives are to demonstrate a cross-link from LEO (Low Earth Orbit) to MUOS (Mobile User Objective System) WCDMA (Wideband Code Division Multiple Access) in GEO (Geosynchronous Orbit). The objective is to send to users on secure networks.
• ICEYE-X2, a X-band SAR (Synthetic Aperture Radar) microsatellite (<100 kg) of Iceye Ltd, a commercial satellite startup company of Espoo, Finland.
• ITASAT-1 (Instituto Tecnológico de Aeronáutica Satellite), a Brazilian 6U Cubesat (~8kg) built by the Instituto Tecnológico de Aeronáutica (ITA). A former rescoped microsatellite mission.
• JY1-Sat, a 1U CubeSat of Jordan developed by students of various universities. The satellite will carry a UHF/VHF amateur radio.
• KazSTSAT (Kazakh Science and Technology Satellite), a microsatellite (105 kg) of Ghalam LLP, Astana, Kazakhstan. Developed by SSTL on a SSTL-50 platform including an SSTL EarthMapper payload designed for global commercial wide-area imaging with a resolution of 18.7 m on a swath of 275 km.
• KNACKSAT (KMUTNB Academic Challenge of Knowledge SATellite) of Thailand, a 1U technology demonstration CubeSat, the first entirely Thai-built satellite, developed by students of King Mongkut's University of Technology North Bangkok (KMUTNB). Use of an amateur radio for communication.
• Landmapper-BC (Corvus BC 4), a 6U CubeSat (11 kg) of Astro Digital (formerly Aquila Space), Santa Clara, CA, USA. The satellite features a broad coverage multispectral (Red, Green, NIR) imaging system with a resolution of 22 m.
• MinXSS-2 (Miniature X-ray Solar Spectrometer-2), a 3U CubeSat(4 kg) of LASP (Laboratory for Atmospheric and Space Physics) at the University of Colorado at Boulder,CO, USA. The objective is to study the energy distribution of solar flare SXR (Soft X-ray) emissions and its impact on the Earth's ITM (Ionosphere, Thermosphere, and Mesosphere) layers.MinXSS-2 is a copy of the MinXSS-1 but with some improvements. — MinXSS-1 was launched on 06 December 2015 onboard of Cygnus CRS-4 to the ISS, were it was deployed into orbit on 16 May 2016. It reentered Earth's atmosphere on 6 May 2017.
• NEXTSat-1, a multi-purpose microsatellite (~100 kg) of Korea designed and developed at SaTReC (Satellite Technology Research Center) of KAIST (Korea Advanced Institute of Science and Technology). The goal is to conduct scientific missions such as star formation and space storm measurements and also technology demonstration in space. Instruments: ISSS (Instrument for the Study of Space Storms) developed at KAIST to detect plasma densities and particle fluxes of 10 MeV energy range near the Earth. NISS (NIR Imaging Spectrometer for Star formation history), developed at KASI (Korean Astronomy and Space Science Institute).
• Orbital Reflector, a 3U CubeSat project (4 kg) of the Nevada Museum of Art and artist Trevor Paylon. The Orbital Reflector is a 30 m sculpture constructed of a lightweight material similar to Mylar. On deployment, the sculpture self-inflates like a balloon. Sunlight reflects onto the sculpture making it visible from Earth with the naked eye — like a slowly moving artificial star as bright as a star in the Big Dipper.
• ORS-7 (Operationally Responsive Space 7), two 6U CubeSats (-7A and -7B) of the USCG (US Coast Guard) in cooperation with DHS (Department of Homeland Security), the ORS (Operationally Responsive Space Office) of DoD, and NOAA. The objective is to detect transmissions from EPIRBs (Emergency Position Indicating Radio Beacons), which are carried on board vessels to broadcast their position if in distress.
• PW-Sat 2 (Politechnika Warszawska Satellite 2), a 2U CubeSat of the Institute of Radioelectronics at the Warsaw University of Technology, Warsaw, Poland. The objective is to demonstrate a deorbitation system - a drag parachute opened behind the satellite - which allows faster removal of satellites from their orbit after it completes its mission.
• RAAF-M1 (Royal Australian Air Force-M1), an Australian 3U CubeSat (~4 kg) designed and built by UNSW (University of New South Wales) for the Australian Defence Force Academy, Royal Australian Air Force. RAAF-M1 is a technology demonstration featuring an AIS receiver, and ADS-B receiver, an SDR (Software Defined Radio).
• RANGE-A and -B (Ranging And Nanosatellite Guidance Experiment), two 1.5 CubeSats of Georgia Tech (Georgia Institute of Technology), Atlanta, GA, USA, flying in a leader-follower formation with the goal of improving the relative and absolute positioning capabilities of nanosatellites.
• ROSE-1, a 6U CubeSat of Phase Four Inc., El Segundo, CA, USA. ROSE-1 is an experimental spacecraft designed to provide an orbital test-bed for the Phase Four RFT (Radio Frequency Thruster), the first plasma propulsion system to fly on a nanosatellite.
• SeaHawk, two 3U CubeSats of UNCW (University of North Carolina, Wilmington), NC. The goal is to measure the ocean color in project SOCON (Sustained Ocean Observation from Nanosatellites). They are considered prototypes for a larger constellation. The SOCON project is a collaboration between Clyde Space Ltd (spacecraft bus), the University of North Carolina Wilmington, Cloudland Instruments, and NASA/GSFC (Goddard Space Flight Center).
• See Me (Space Enabled Effects for Military Engagements), a prototype microsatellite (~22 kg) built by Raytheon for DARPA to obtain on-demand satellite imagery in a timely and persistent manner for pre-mission planning.
• SkySat-14 and -15. Planet of San Francisco has 13 SkySats in orbit. The commercial EO satellites were built by Terra Bella of Mountain View, CA, which Planet acquired from Google last year. At the time of the purchase, there were 7 SkySats in orbit. On 31 October 2017, Planet launched an additional six on a Minotaur-C rocket. The 100 kg SkySats are capable of sub-meter resolution – making them the most powerful in the constellation. Customers can request to have these high-resolution satellites target their locations of interest.
• SNUGLITE, a 2U CubeSat designed by the SNU (Seoul National University) for technology demonstrations and amateur radio communication.
• SpaceBEE, four picosatellites of Swarm Technologies (a US start-up), built to the 0.25U form factor to make up a 1U CubeSat.
• STPSat-5 is a science technology minisatellite of the US DoD STP (Space Test Program), managed by the SMC of the USAF. STPSat-5 will carry a total of five technological or scientific payloads to LEO (Low Earth Orbit) in order to further the DoD's understanding of the space environment. The satellite was built by SNC (Sierra Nevada Corporation) on the modular SN-50 bus with a payload capacity of 50-100 kg and compatible with ESPA-class secondary launch adaptors.
• THEA, a 3U CubeSat built by SpaceQuest, Ltd. of Fairfax, VA to demonstrate a spectrum survey payload developed by Aurora Insight, Washington DC. The objective is to qualify Aurora's payload, consisting of a proprietary spectrometer and components, and demonstrate the generation of relevant measurements of the spectral environment (UHF, VHF, S-band). The results of the experiment will inform future development of advanced instrumentation by Aurora and component development by SpaceQuest.
• VESTA is a 3U CubeSat (4 kg) developed at SSTL in Guildford, UK. VESTA is a technology demonstration mission that will test a new two-way VHF Data Exchange System (VDES) payload for the exactEarth advanced maritime satellite constellation. Honeywell Aerospace is providing the payload. VESTA is a flagship project of the National Space Technology Program, funded by the UK Space Agency and managed by the Center for EO Instrumentation and Space Technology (CEOI-ST).
• VisionCube-1, a 2U CubeSat designed by the Korea Aerospace University (KAU) to perform research on Transient Luminous Events in the upper atmosphere. The image processing payload consists of a multi-anode photon multiplier tube(MaPMT), a camera, and a real-time image processing engine built by using SoC (System-on-Chip) FPGA technologies.
• ZACube-2 (South African CubeSat-2), a 3U CubeSat of F'SATI (French South African Institute of Technology) at CPUT (Cape Peninsula University of Technology), Cape Town, South Africa (in collaboration with SANSA and Stellenbosch University).The payloads include a medium resolution matrix imager and a number of communication subsystems. The prime objective of ZACUBE-2 is to demonstrate AIS (Automatic Identification System) message reception using its SDR-based payload. The launch of ZACube was planned for 2018 on an Indian PSLV rocket but has been moved to a Falcon-9 v1.2 vehicle from VAFB.
Spaceflight has contracted with 64 spacecraft from 34 different organizations for the mission to a Sun-Synchronous Low Earth Orbit. It includes 15 microsatellites and 49 CubeSats from both commercial and government entities, of which more than 25 are from international organizations from 17 countries, including United States, Australia, Italy, Netherlands, Finland, South Korea, Spain, Switzerland, UK, Germany, Jordan, Kazakhstan, Thailand, Poland, Canada, Brazil, and India. 14)
Figure 6: This infographic released by Spaceflight illustrates the types of payloads booked on the SSO-A mission (image crdit: Spaceflight)
Sensor complement (EarthMapper, RadMon)
The Ghalam LLP developed instrument RadMon will be added when descriptions are available.
EarthMapper is a global imaging system providing full coverage of the Earth's land area in 5 days. The EarthMapper instrument is of SLIM6 (Surrey Linear Imager Multispectral 6 channels - but 3 spectral bands) heritage, flown on the Deimos-1 and UK-DMC-2 missions (launch July 29, 2009). The instrument consists of two bore‐sighted instrument banks. The design provides for a nadir-viewing, three-band multispectral scanning camera capable of providing mid-resolution image information of the Earth's surface.
SLIM6 employs the pushbroom imaging technology using two cameras per band (mounted in a double-barrel cross-track configuration - or in two banks) thus providing a dual (slightly overlapping) swath with a combined swath width of ~ 600 km with a spatial resolution 17.5 m GSD (Ground Sampling Distance) at nadir. 15)
The imager comprises six lens and sensor pairs, configured in two banks as part of an overall optical bench assembly. The banks are mounted angled away from nadir by approximately 13º, to double the swath width, but with a small overlap of approximately 5% to aid image stitching. The FOV (Field of View) from each bank is 26.6º.
Applications: Suitable for a wide variety of commercial, environmental and security applications. EarthMapper continuously images the sunlit land mass and is particularly suited to applications requiring a high temporal revisit rate. Typical examples include:
• Agricultural monitoring
• Flood monitoring
• Water quality
• Disaster management
• National and urban mapping.
Table 2: Parameters of the SLIM6 (SLIM6) instrument
The upgraded SLIM6 consists of two bore‐sighted instrument banks. The SLIM6 design provides for a nadir-viewing, three-band multispectral scanning camera capable of providing mid-resolution image information of the Earth's surface.
Figure 7: Schematic illustration of the SLIM6 configuration (image credit, SSTL)
The architecture of the KazSTSAT features a highly distributed nature with the main ground station, Spacecraft Operations Center, and main Mission Planning System located in three different geographical locations in Svalbard, Astana and Guildford. On top of that, there are provisions for backup ground station and MOC in Astana. Some of the customers are also expected to receive their imagery directly to their ground stations. All this have driven an innovative architecture and design of the components of the ground segment. 16)
The ground segment of the KazSTSAT mission is going to be based on a standard SOC (Spacecraft Operations Center) and MOC (Mission Operations Center) configurations.
The experimental part consists of the ground station based on SDR (Software Defined Radio). Connection to the remote ground stations will employ Ethernet over IP (Internet) that would be LAN transparent for both SOC and the SDR ground stations. The MOC (Mission Operations Center) will include new distributed Mission Planning System and image processing software.
S-band uplink and downlink chains:
Modern SDR technology is now mature enough to be used in commercial grade applications, including ground stations. The use of Ettus Research SDR's significantly reduces the cost of a GSN (by an order of magnitude) and visibly simplify the GSN (Ground System Network) architecture. Ettus Research B200 is considered as baseline, this model has sufficient bandwidth for the S-band uplink and downlink purposes (19.2 kbit/s CPFSK and 38.4 kbit/s BPSK/QPSK ½ k=7 respectively). Software composed of bespoke C++ and Python modules combined with the GNU-Radio environment is running on a medium level SDR host computer (Intel Core i5, 8 GB RAM, 250 GB SSD) running Ubuntu Linux which more than sufficient for the purpose.
As all the processing after a direct RF conversion stage is performed in in-house developed software, this configuration is easily modified for any uplink and downlink modulation, coding, randomization, and rate combinations.
The imagery is downloaded from the satellite using the Saratoga protocol which is IP-based and requires an uplink connection for sending negative acknowledgement and other types of IP packets. This requires full de-encapsulation of the X-band IP traffic in real time. For this mission a new configuration of a ViaSat-800 or Omnisat-G3LT X-band receiver interfaced via an Ethernet output port with a PC running a custom soft-ware suite is going to be employed. The X-band receivers are performing demodulation and FEC decoding, while an in-house software suite is dealing with the re-output receiver protocol, V.35 descrambling, HDLC de-encapsulation, and NRZ decoding. After de-encapsulation the IP packets are transferred to the standard IP-stack and either forwarded to the Ethernet interface, or consumed by the Saratoga-Win application, running locally on the same PC.
Figure 8: Top: Comparison between a typical standard S-band ground station architecture: Bottom: the KazSTSAT GSN based on the SDR technology (image credit: Gahlam LLP)
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (firstname.lastname@example.org).