Content uploaded by Massimiliano Pastena
Author content
All content in this area was uploaded by Massimiliano Pastena on Sep 02, 2020
Content may be subject to copyright.
A Compact Multispectral Imager
for the MANTIS Mission 12U CubeSat
Rafael Guzmán*a, Ricardo Lópeza, Eider Ocerina, Stuart Davisa, Juan Tomás Hernania,
Rob Brennan-Craddockb, Nick Kellemanc, Massimiliano Pastenad, Nicola Melegae & Flavio
Marianif.
aSatlantis Microsats SL, Edif. SEDE, Parque Científico, Campus UPV Bizkaia, 14 D - 2ª planta 48940
Leioa, Spain; bOpen Cosmos Ltd., Electron Building, Fermi Avenue, Harwell, OX11 0QR, United
Kingdom; cTerrabotics Ltd., 52 Horseferry Rd., Westminster, London, SW1P 2AF, United Kingdom;
dESA/ESTEC, Keplerlaan 1, PO Box 299, 2200AG Noordwijk, The Netherlands; eAurora Technology
B.V., Zwartweg 39, 2201 AA Noordwijk, The Netherlands, for ESA; fHE Space Operations B.V,
Huygensstraat 44, 2201 DK Nordwijk, The Netherlands, for ESA.
ABSTRACT
The requirements of the natural resources sector for remote sensing products are generally very demanding both in terms
of data quality and coverage/revisit time. The MANTIS mission (Mission and Agile Nanosatellite for Terrestrial Imagery
Services) is being developed to specifically fulfil those requirements using a compact and agile 12U Cubesat system.
MANTIS will embark the iSIM90-12U (integrated Standard Imager for Microsatellites) an innovative high-resolution
optical payload for Earth Observation missions developed by Satlantis Microsats SL. The payload consists of a compact
binocular telescope specifically designed to fit within a volume of 8U, and thus ideal for 12U CubeSat standard platforms.
The design relies on iSIM technology, comprised by the integration of four key technologies: a binocular diffraction-
limited optical system working at visible and near-infrared wavelength; a high precision, robust and light structure; a set
of innovative COTS detectors with 2D CMOS sensors; and a high-performance and reconfigurable on-board processing
unit with super-resolution algorithms implemented. Open Cosmos Ltd. as Prime is responsible for the end-to-end space
mission service, including the provision of a new generation 12U spacecraft platform, while Terrabotics Ltd. will analyse
and provide data to the end users. The mission is funded by the European Space Agency’s InCubed (Investing in Industrial
Innovation) program supporting innovative activities related to Earth Observation enabling European industry to compete
commercially in the global marketplace. An overview of the development status of the mission will be presented focusing
on the consolidation of the payload design and the mission end products.
Keywords: High-Resolution, Optical Payload, Earth Observation, 12U CubeSat, Oil and Gas, InCubed.
1. INTRODUCTION
InCubed (Investing in Industrial Innovation) is an element of the European Space Agency (ESA) Earth Watch, the
operational service driven program ESA implements with external partners and that includes, among others, the
exploitation of the meteorological satellites and the Copernicus program. InCubed’s main objective is to improve European
industry competitiveness in the Earth Observation (EO) global market, supporting -through a co-funding scheme- the
realization of high-risk/high-potential industry-led product developments. In particular, InCubed supports developments
of EO space and ground systems as well as data products and end-to-end solutions. Flight items developments include
payload, platforms, and entire satellites as stand-alone missions or as in-orbit demonstration of constellations [1]. In this
context, the “Mission and Agile Nanosatellite for Terrestrial Imagery Services” (MANTIS) project was selected in 2019
for full implementation, starting from phase B (Preliminary Definition) up to E2 (Flight Readiness and Operations).
*guzman@satlantis.com; phone +34 944 344 780 (Spain), +1 352 283 4845 (USA); www.satlantis.com
CubeSats and SmallSats for Remote Sensing IV, edited by Thomas S. Pagano, Charles D. Norton,
Sachidananda R. Babu, Proc. of SPIE Vol. 11505, 1150507 · © 2020 SPIE
CCC code: 0277-786X/20/$21 · doi: 10.1117/12.2568080
Proc. of SPIE Vol. 11505 1150507-1
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
MANTIS is a demonstration mission to develop, build, launch and operate an innovative nanosatellite, and provide low-
latency and targeted imagery tailored to the data needs of the oil and gas sector. Oil and gas resources are found in remote,
hostile, and hazardous regions around the world, with energy companies increasingly taking on more complex and
expensive projects to locate and produce these resources. Resources are often difficult to access politically, economically
and physically. As a result, there is an increasing need to access affordable market data and analysis tools. The globally
disperse location and number of global oil and gas assets make it difficult for ongoing monitoring and mapping of oil and
gas supply through independent sources. Additionally, the global oil and gas supply chain is not accurately or frequently
monitored to provide data to other stakeholders in the energy market including regulators, financial services, and
economists to name a few. The current space imagery market offering is not tailored to specific industry use cases within
the oil and gas sector, and instead are typically sized and tailored to serve the requirements of other sectors such as Military
and Defense.
The MANTIS mission aims to provide a vertically integrated remote sensing solution built specifically to address these
specific needs of the oil and gas sector. MANTIS brings together the expertise of three space companies (see Figure 1):
• Open Cosmos Ltd (Harwell, UK) will be providing a new generation 12U spacecraft platform. As Prime, Open
Cosmos is responsible for the end-to-end space mission service (covering the Space, Launch, Ground and User
segments of the mission). In order to enable the delivery of services across these segments, Open Cosmos will
be leveraging its strategic partnerships with key players in the industry. A data processing chain managed by
Open Cosmos on-ground will enable processing the raw satellite imagery up to Level 1C.
• Satlantis Microsats SL (Bilbao, Spain) will provide a high-resolution imaging payload (iSIM90-12U). The
payload consists of a compact binocular telescope specifically designed to fit within a volume of 8U. The design
relies on iSIM technology, comprised by the integration of four key technologies: a binocular diffraction-limited
optical system working at visible and near-infrared wavelength; a high precision, robust and light structure; a set
of innovative COTS detectors with 2D CMOS sensors; and a high-performance and reconfigurable on-board
processing unit with super-resolution algorithms implemented. It will provide a fully processed image data set up
to Level 1B.
• Terrabotics (London, UK), a satellite data analytics company in the natural resources sector with a specific focus
on the oil & gas industry, will be the primary client of the MANTIS mission. It derived the information
requirements necessary for the MANTIS mission to address specific use cases in the oil & gas sector. After
receiving the Level 1C data from Open Cosmos, Terrabotics will apply their proprietary change detection and
object recognition algorithms to this imagery in order to carry out further processing and analysis of data to create
added-value products (Level 2+) that will feed their PADS™ Premium service. As part of this process, Terrabotics
will be consolidating the MANTIS data with lower resolution data available from third party data sets (e.g. from
ESA’s Copernicus program).
Figure 1: MANTIS Mission Value Chain
Proc. of SPIE Vol. 11505 1150507-2
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Differentiating attributes of the MANTIS mission will be an acquisition plan designed specifically around oil and gas
provinces, a new economic model to increase affordability, and a greatly simplified End User License Agreement (EULA)
to encourage use. While sensor data will be available to purchase from MANTIS, the primary product will be an
information service provided by Terrabotics, which will provide decision-ready insights to end-users, greatly reducing the
processing and analysis overhead associated with Earth Observation. Through the use of the satellite imagery provided by
the MANTIS mission, Terrabotics is seeking to offer a “Premium Tier” of their existing analytical solutions and value-add
products, in order to market this product to existing and future customers. In this way Terrabotics is seeking to build on
their flagship PADS™ product and further address specific use cases demanded by end-users in the oil & gas sector.
The MANTIS mission is composed of the Space, Ground, User and Launch segments. The mission architecture is depicted
in Figure 2, including the individual elements that comprise each segment. The 12U spacecraft platform contained within
the Space Segment is described in further detail in Section 2. The Ground Segment is responsible for receiving and
processing the satellite imagery up to Level 1C, while the User Segment is responsible for the creation and distribution of
added-value products (Level 2+). OpenApp, Open Cosmos’s proprietary mission control software, is currently undergoing
qualification in support of another Open Cosmos mission and will complete qualification in 2020.
Regarding the selection of the satellite orbit, the primary constraint is maximising the potential image quality that can be
provided by the payload. This lies within achieving the required spatial resolution, and the trade-off between maximising
Signal-To-Noise of an imaged scene, and minimising the risk of non-uniform illumination (eg. sun-glinting). Secondary
constraints include maximising fraction of global coverage and reducing the required design complexity. The selected orbit
is sun-synchronous, at an altitude of 500km, and a Local Time of Descending Node at 10:30. The launch date for the
mission is yet to be announced.
The Areas of Interest (AOIs) targeted by the mission have been defined considering the regions of highest activity in the
natural resources sector. Short term variations in market demands are also satisfied by autonomous tasking based on inputs
from the end user on new Points of Interest (POIs). End users will be able to submit requests for tasking the satellite by
submitting these to Open Cosmos’s Mission Operations Centre. These requests will inform the definition of the image
acquisition plan.
Figure 2: MANTIS Mission Architecture. Blue elements are provided by members of the MANTIS consortium.
Proc. of SPIE Vol. 11505 1150507-3
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
2. THE 12U CUBESAT PLATFORM
2.1 Overall Description of the 12U CubeSat Platform
The Open Cosmos satellite is a modular platform that can meet the requirements of a variety of missions. This modularity
is achieved by standardization of interfaces between subsystems and within them as well. This enables Open Cosmos to
have different options to cater for the mission needs. Interface boards allow the addition of third-party subsystems that do
not follow the Open Cosmos interfaces enabling the increase in capabilities of the platform or tailoring to specific missions.
The platform has been designed for Low Earth Orbit (LEO) and for any inclination, and is compatible with a wide variety
of commercial launches. The key characteristics of the MANTIS 12U platform are summarized in the table below, with a
visualization of the platform shown in Figure 3.
Table 1: 12U Platform characteristics
Payload mass capacity
10 kg
Payload volume capacity
8U
Payload orbit average power
15 W
RF Comms
S-Band: 1 Mbps
X-Band: 150 Mbps
Battery capacity
90 W hr
Pointing accuracy (APE)
60 arcsec
Pointing stability (RPE)
15 arcsec/s
Figure 3: MANTIS 12U Platform Concept
Proc. of SPIE Vol. 11505 1150507-4
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Mechanical
The thermal and mechanical subsystems are very coupled using the primary structure as main conductive link within the
platform and closure panels as main passive thermal management system with the space environment. The mechanical
system consists of:
• Primary structure: modular structure that can be tailored from 3U to 12U. Other options are possible with
minimal redesign.
• Secondary structure: internal structures such as trays, boxes for subsystems, brackets, etc.
• Closure panels: can contain solar cells and different optical properties to tailor to the thermal environment of the
mission.
The 12U structure is based upon the 6U CubeSat standard [2] and complies with the requirements imposed by COTS
deployers for 12U CubeSats.
Electrical Power System (EPS)
The EPS has a wide variety of power distribution channels that can be configured to suit the mission needs. The EPS is
divided into two subsystems. EPSA1 providing the interface to the solar arrays, battery charging, and power distribution.
While EPSA2 contains the batteries and battery cell management.
Switchable rails are provided at 3.3V, 5V and at battery voltage.
Communications (COMMS)
The COMMS subsystem is composed of an S-band transceiver acting as primary TT&C and a high data rate X-Band sub-
system. The S-Band antenna system creates a quasi-omni-directional pattern ensuring access to ground stations
independent of the satellite state. The X-Band system meanwhile is a DVBS2 compatible X-band transmitter system
consisting of an active antenna and SDR-based modem, and will provide downlink rates of at least 150 Mbps. The satellite
agility is utilised during ground station passes, to maximise the link margin and quantity of payload data downloaded.
Attitude and Orbit Control System (AOCS)
The AOCS is a subsystem highly tailored to the mission requirements and configuration. It is for this that different options
are available to cater for a wide range of missions. The AOCS consists of the following modules:
• ADCS subsystem
o Low performance ADCS, small platforms (3U-6U)
o High performance ADCS, big platforms (6U-12U)
• GNSS receiver
• Propulsion
The MANTIS ADCS includes 3 Reaction Wheels, 3 Magnetorquers, and 1 Star tracker.
Backplane
The backplane acts as the central connection hub, routing data and power lines from the Open Cosmos modules to the
rest of the satellite (except the 3rd party modules that might use other interfaces). The backplane mechanically mounts
onto the Open Cosmos modules that in turn mechanically connect to the primary structure. The electronic connections
are made via board-to-board connectors between subsystem and backplane. The backplane hosts the connectors for the
satellite to payload interface.
The backplane also provides electrical interfaces to the solar panels, deployables and pusher switches for activation. The
backplane contains the umbilical interface for ground use (power and data) and the remove before flight (RBF) to inhibit
deployment and activation of the satellite during ground use.
The platform consists of the following subsystems:
2.2 Key Sub-systems and/or Innovations of the 12U CubeSat Platform
Proc. of SPIE Vol. 11505 1150507-5
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Mechanical) have undergone qualification testing, while externally procured subsystems are required to have a minimum
Technology Readiness Level (TRL) 8 at the start of Phase D.
The development philosophy of the MANTIS platform is centered upon the re-use of qualified core avionics, both as
internal developments and procured items, qualified at system-level through a dedicated Engineering/Qualification Model
(EQM) campaign, before manufacture and acceptance of a Flight Model (FM).
The EQM will verify the mechanical, electrical and software interfaces of platform subsystems, before integrating the
payload QM. The EQM campaign is also expected to provide a deeper understanding of system-level effects leading to
degradation of the final image quality. Once the EQM is stable, it will undergo end-to-end qualification tests to qualify the
subsystems and the system and rehearse the processes towards FM. The EQM and its subsystems also act as back up for
the FM.
As depicted in Figure 4 below, the EQM campaign also ensures qualification of the Ground and User segments, specifically
focusing on the interfaces between each segment, i.e. between Platform & Ground Station, and between the Image
Processing Centre & Information Platform.
Figure 4: MANTIS AIT Program
Critical technologies of the mission which have been prioritized for early de-risking include:
• Payload data transmission via X-Band
The “Early campaign” includes early integration and assembly of the on-board data handling system to demonstrate
adequate performance of the platform with respect to the large amounts of data generated by the payload.
• Pointing stability during image acquisition (eg. Microvibrations)
The Microvibration Derisking Campaign (MDC) will conduct free-free testing of a quasi-structural model of the satellite,
in order to ensure accurate correlation of the Finite Element Model.
The Design Configuration Baseline of the platform has been frozen as of successful completion of the mission’s
Preliminary Design Review in Q2 2020, and preparations for these test campaigns are underway.
Open Cosmos tackles heritage at component and satellite architectural level, and all technology is based on off-the-shelf
components which have -or are shortly due to be- launched into space. The core subsystems (including the OBDH, EPS,
2.3 Status of the Platform Development
Proc. of SPIE Vol. 11505 1150507-6
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
3. THE “ISIM” CONCEPT: AN INNOVATIVE IMAGING PAYLOAD FOR EO
3.1 Overall Description of iSIM90-12U
The “integrated Standard Imager for Microsatellites” (iSIM) is a state-of-the-art, high-resolution, multi-spectral, agile
optical imager developed by Satlantis for the new generation of EO microsatellites constellations. The iSIM design
combines class leading performance, via the utilization of cutting-edge technologies, standardized manufacturing
procedures, significantly reduced build times and a new level of affordability. This combination approach will provide
industries and government agencies with the ability to acquire and access unparalleled high-resolution data in real-time.
Satlantis has currently developed two versions of this camera: iSIM170, designed for the 50-100 kg microsatellite
platforms, and iSIM90 for the 12U-16U CubeSat platforms.
iSIM90-12U uses a modified Maksutov-Cassegrain optical design with a focal length of 775 mm and an effective aperture
diameter of 77.5 mm. The imager is designed to provide diffraction-limited images between 450 and 1000nm over the
entire 1.8o FOV in RGB+NIR spectral bands, with a spatial resolution of ~2 m in RGB and ~2.5 m in NIR, and a 13 km
swath (at 500 km altitude). The system relies on the technological integration of four key elements:
• A diffraction-limited optical design of a binocular telescope, each consisting of just three optical elements with
all spherical surfaces (Figure 5).
• A high precision, quasi-athermal, robust and light alloy structure supplemented with carbon fiber rods (Figure 6).
• A set of COTS 2D CMOS detector units, rugged to withstand vibration, thermal and radiation effects (Figure 7).
• A very high-performance, reconfigurable, on-board image processor (Figure 8).
Figure 5: iSIM90 optical design.
The iSIM90-12U utilizes the certified core technologies already validated in space for iSIM170, through developmental
evolution and mission specific tailoring of these technologies. The following enhanced elements have been incorporated
into this new generation of high-resolution imager:
• 12U CubeSat-optimized mechanical structure.
• Improved thermomechanical design.
• Enhanced optical design and performance.
• Multispectral capability.
• New generation of Electronic and Control Systems.
• Implementation of platform communications protocol.
Proc. of SPIE Vol. 11505 1150507-7
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Figure 6: Opto-mechanical structure of the binocular iSIM90-12U payload.
Figure 7: COTS detector units housing the CMOS CMV1200 before the ruggedization procedure.
Figure 8: New “SPoCK” electronic board (green) of the Electronic Control System (in charge of image acquisition and on-board
image processing), and “Smart Heater” electronic board (blue) of the Thermal Control System (in charge of thermal stabilization).
Proc. of SPIE Vol. 11505 1150507-8
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Finally, the fully integrated camera opto-mechanics and electronics are depicted in Figure 9. The technical characteristics
of the iSIM90-12U camera are summarized in Table 2.
Figure 9: Fully integrated design of the opto-mechanics and electronics of iSIM90-12U.
Table 2: Summary of iSIM90-12U tailored for MANTIS mission
CHARACTERISTICS
PERFORMANCE SPECIFICATION
Spectral bands
4 (RGB, NIR)
GSD at 500 km (raw image)
≤ 3.5m
GSD at 500 km (post-processed image
including degradation due to platform
and orbital effects)
RGB: 2.5m
NIR: 3.0m
Swath width
13.0 km
Signal-to-noise-ratio (SNR)
SNR=55 per resolution element for targets such as:
Vegetation, with minimum solar elevation angle of 55o
Sand, with minimum solar elevation angle of 34o
Volume of optomechanical subsystem
6U (including shared volume between secondary structures)
Volume of ECS subsystem
2U
Peak power (Acquiring & Heating)
40.6 W
*Operational temperatures
Opto-Mechanics: +19.5 to +26.5°C
ECS: -30 to +70°C
Detectors: -5 to +40°C
Non-operational temperatures:
Opto-Mechanics: -20 to +40°C
ECS: -40 to +85°C
Detectors: -30 to +70°C
Proc. of SPIE Vol. 11505 1150507-9
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
*The operational temperature range allows the optics to perform in optimal level. However, iSIM90-12U has a broader operational
range thanks to the TCS. This operational range is dependent on the systems configuration. The configuration of the TCS is linked to
environmental factors, interface and power, and its design and configuration shall be optimized together with the platform developer.
iSIM90-12U offers the same spectral bands specified by ESA Sentinel EO satellites, as shown in the following table.
Table 3: Filter bands in iSIM90-12U
Spectral Band
Spectral Range (nm)
Band 1 (Blue)
459 - 525
Band 2 (Green)
541 - 577
Band 3 (Red)
650 - 680
Band 4 (Infra-red)
780 - 886
3.2 The Three Key Innovations of the iSIM Concept
1.- Super-resolution: The iSIM camera, whether iSIM170 or iSIM90, is designed to be diffraction-limited. As such, its
spatial resolution is limited by the size of the optics, instead of by the detector pixel size. Together with our observation
strategy, this design allows for super-resolution techniques that can improve the native resolution of the imager by a factor
of 2-3. The iSIM camera works as a staring imager, that is, it produces a two-dimensional field of view at once thanks to
the use of 2D CMOS sensor arrays. During acquisition, images are taken at a high frame rate and at short exposure times
with respect to the satellite motion to ensure (1) no blurring during movement along the orbit, and (2) a sequence of images
with a common area of overlap that are combined to create high signal-to-noise, super-resolved images. This technique
has been tested successfully in panchromatic mode during the In-Orbit-Demonstration (IOD) of the iSIM170 payload,
launched to the International Space Station (ISS) in May 2020 (see Figure 10).
Figure 10: Panchromatic images taken with iSIM170 during the IOD from the ISS. Left: airport in Provence (France). Right: town in
Huelva (Spain). In both cases, the red and blue cutouts show zoomed-in areas to illustrate the changes “before” and “after” our super-
resolution technique.
iSIM170 was installed in June 2020 on the i-SEEP platform of the Japanese Kibo module of the ISS. The goal of this IOD
mission consists of commissioning the payload and characterizing the overall instrument’s capabilities, specially its ability
to provide a factor around 2-3 improvement in spatial resolution below its diffraction limit design in panchromatic spectral
band, using Satlantis super-resolution algorithms. The payload will be operating till September 2020 to achieve TRL-8
qualification performing uplink and downlink activities managed by JAXA.
Proc. of SPIE Vol. 11505 1150507-10
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
As shown in Figure 10, these preliminary results have already demonstrated the success of this IOD mission. For instance,
the distance between the stripes of the airport runway is around 1m, while the helicopter blades clearly seen in another part
of the same image have a width of 80cm. This is about 2.5 times better than the nominal spatial resolution of the diffraction-
limited iSIM170 camera before the super-resolution technique is applied.
2.- Multi-spectrality without loss of resolution: Since the optical channels of the iSIM camera are parallel to each other,
they will observe the same area on ground. Thus, each channel can be used to acquire images of the same area on ground
but at different spectral ranges, adding the multispectral capability to the imager. Multispectral imaging is achieved with
filters placed over the detector, such that each filter covers multiple rows of the sensor. The filters are oriented
perpendicular to the along-track direction to ensure that all filters scan the desired area as the satellite moves along its
orbit. This is illustrated in Figure 11. Note that, contrary to the traditional multi-spectral EO camaras where the spatial
resolution is degraded proportionally to the number of bands, in the SIM technology, spatial resolution is independent of
the number of color bands from VIS to NIR.
Figure 11: Sketch illustrating the implementation of our multispectral capability without loss of spatial resolution.
3.- Agility: Since iSIM works by taking images at a very high frame rate and with very short exposure times with respect
to the satellite motion, iSIM is the only camera in the market able to take images while the satellite moves along and across
its orbit. As a result, iSIM is specifically designed to monitor linear irregular structures on Earth (e.g., coastlines, pipelines
or borders; see Figure 12).
Figure 12: Illustration of iSIM’s agility: (a) traditional EO cameras operate at a fixed scanning angle; (b) iSIM can take images while
the satellite moves along and across its orbit; (c) actual iSIM images taken from an airplane demonstrating its agility capability.
Proc. of SPIE Vol. 11505 1150507-11
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
As shown above, the first of these three innovative aspects of the iSIM camera concept (super-resolution) has already been
demonstrated with the iSIM170 IOD at the ISS. The other two key innovations (multi-spectrality without loss of resolution
and agility) will be demonstrated in 2021 with a second IOD flight to the ISS. This time, Satlantis will be launching the
iSIM90 camera model as part of the CASPR mission, sponsored by the Space Test Program Houston-7 of the USA DoD,
in collaboration with SHREC/University of Pittsburgh and the University of Florida.
Finally, the iSIM camera concept developed by Satlantis also includes the Smart Image Processing Algorithm (SIPA). This
algorithm takes advantage of the payload’s design, imaging configuration and observation modes. The concept of SIPA
resides in combining a set of consecutive 2D images that share a common overlapping area. This combination can improve
the signal-to-noise (SNR), contrast (MTF) and spatial resolution (GSD) of the final processed image. Note that the three
parameters cannot be maximized simultaneously. Therefore, a trade-off based on the end-use of the image and the
requirements of the specific mission application must be done. As such, SIPA is designed to offer three processing modes
of the same images, depending on data applications: (1) bright mode, which gives priority to the SNR, (2) constrast mode,
which gives priority to the contrast and (3) precision mode, which gives priority to the spatial resolution (Figure 13).
Figure 13: SIPA different modes (from left to right): Bright mode, Contrast mode and Precision mode.
3.3 Status of the iSIM90-12U Camara
The iSIM90-12U camera is based on the same iSIM90 camera that will be launched to the ISS in 2021 as part of the
CASPR mission mentioned above. The Flight Model (FM) of iSIM90 will be ready in September 2020. The figures below
show some relevant aspects of this development for the MANTIS mission.
Figure 14: Interferogram showing intensity and wavefront error of the iSIM90-12U optics. The quality of the assembled optics is
excellent (rms= 0.045 lambda at 632.8nm), fully consistent with the theoretical diffraction-limited value.
Proc. of SPIE Vol. 11505 1150507-12
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Figure 15: One of the two primary mirrors for iSIM90 (left) and its optic quality validation (right) for the CASPR mission.
Figure 16: CMOS Sensor for iSIM90 with the Green and Blue filters (left), Red and NIR filters installed (middle) and installed on the
iSIM-90 opto-mechanical structure of the Flight Model for the CASPR mission (right).
Figure 17: Opto-Mechanical subsystem of iSIM90 in the difference phases of the assembly for the CASPR mission: structure (left),
structure with external and internal baffles (middle) and structure with the internal MLI (right).
Proc. of SPIE Vol. 11505 1150507-13
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Figure 18: SPoCK electronics render with the location of the main components of the board, currently being manufactured.
iSIM90-12U is designed to be integrated in the 12U CubeSat platform provided by Open Cosmos (Figure19).
Figure 19: Sketch of iSIM90-12U inside the 12U CubeSat platform designed by Open Cosmos.
For the iSIM90-12U qualification campaign four models are going to be built and tested (see also Table 4):
• Engineering Model (EM) in order to validate the functionalities, interfaces and performances of electrical and
software interfaces.
• Qualification Model Minus (QM-) to represent the Flight Model’s primary structure. The size, mass properties
and dynamic behavior and mechanical interfaces are similar to the FM.
• Qualification Model Plus (QM+) in order to qualify all aspects (environmental, functional, interface and
performance) of the iSIM90-12U payload. The QM+ optomechanical structure is constructed to a full flight
specification. The electronic system and control software will be a beta version.
• Flight Model (FM) will be the definitive version of the camera and will undergo an acceptance level process,
including environmental tests.
Proc. of SPIE Vol. 11505 1150507-14
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Table 4: Tests to be performed to the iSIM90-12U four models during the qualification campaign
Test Group
Test
EM
QM-
QM+
FM
Physical Test
Dimensional
-
x
x
x
Mass properties
-
x
x
x
Mechanical
Environment
Resonance Search
-
-
x
x
Sine Burst
-
-
x
-
Random Vibration
-
-
x
-
Workmanship verification (random)
-
-
-
x
Thermal Environment
Thermal vacuum cycling
-
-
x
x
Electrical
Grounding & Bonding
-
-
x
x
Power
x
-
x
x
Payload Optical
Optical performance (Test 1)
-
-
x
x
Optical performance (Test 2)
-
-
x
x
Communications
Communications and Operations
x
-
x
x
4. SIMULATIONS OF MANTIS COMMERCIAL APPLICATIONS
Terrabotics’ commercial oil and gas information services are powered by satellite imagery data. The role of MANTIS is
to provide an up-to-date stream of high-resolution optical imagery to detect and measure change occurring at oil and gas
infrastructure around the world. To meet this requirement, MANTIS must be able to detect a range of infrastructure targets
not detectable by medium resolution systems such as Sentinel-2 or Landsat-8. To assess the future capabilities of MANTIS,
iSIM90-12U imagery was simulated by Satlantis and the simulated imagery were passed to Terrabotics’ detection and
classification workflow. The resultant detections were assessed against detections from the control imagery.
Simulations were performed using a MAXAR WorldView-3 image acquired over the Permian geologic basin in the United
States on 20th January 2015 at 17:25 UTC [3]. The image was also used as the control for assessing detection and
classification accuracy. The WorldView-3 image was acquired 14º off-nadir with a solar elevation angle of 33.8º and
covered an area of 10km by 10km. The imaging area included a range of oil and gas infrastructure items representative of
the targets MANTIS will be required to image once operational. MAXAR’s WorldView-3 satellite captures multispectral
imagery in the red, green, blue and near-infrared of the spectrum coincident with MANTIS. At a multispectral spatial
resolution of 1.24m nadir, and with a bit depth of 11 bits, WorldView-3’s multispectral spatial and radiometric resolution
meet and exceed Terrabotics’ requirements for automatic oil and gas infrastructure detection and classification, making
the imagery suitable for simulating iSIM90-12U imagery.
Proc. of SPIE Vol. 11505 1150507-15
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
Figure 20: An overview of the WorldView-3 image used for the simulation and assessment of iSIM90-12U images.
Oil and gas infrastructures can be seen across the image with well pads visible as light rectangles (see Figure 20). A water
pit is also visible to the center left of the image. At finer detail (inset to the right), different equipments can be seen at each
of the pads, indicative of different processes in a well pad’s lifecycle and critical to Terrabotics’ information products.
Terrabotics calibrated the WorldView-3 imagery to top-of-atmosphere spectral radiance (Wµm-1m-2sr-1). To aid the
assessment of the change detection algorithms, Terrabotics generated a simulated event in the calibrated WorldView-3
image. The two calibrated images were then provided to Satlantis to simulate iSIM90-12U imagery. Satlantis used these
series of radiometrically calibrated high-resolution input images to simulate iSIM90-12U observations in the
panchromatic, RGB and NIR bands. Different noise scenarios were simulated, using a range of realistic solar elevation
angle as well as different off-nadir satellite pointing.
The simulated scenarios were: (1) panchromatic images at various noise levels, (2) RGB and NIR and (3) RGB and NIR
modified images at various noise levels and off-nadir pointing of the satellite. For each scenario, a series of raw images as
well as super resolved images with superior spatial SNR compared with the raw images were generated.
Three solar elevation angles were used for the simulation of noise scenarios: 60, 33.8 and 10 degrees. Photon shot noise
was added to the image, with Poisson distribution form with a mean of N and a standard deviation of the square root of N,
where N is the number of counts in pixel.
The off-nadir pointing simulations are particular due to two effects, (1) an effective change in the orbital height of the
satellite which in turn increases both the GRD's and GSD of the observations, and (2) a foreshortening effect due to the
curvature of the Earth's surface causing an additional increase in GRD and GSD. Three off-nadir pointing angles of 10,
30, and 50 degrees were modelled.
The change in effective orbital height was calculated using the trigonometric sine rule and the foreshortening was modelled
by multiplying the image's x-axis by the cosine of the off-nadir angle. This assumes that the Earth takes the shape of a
cylinder and that the detector y-axis is orientated in parallel to the Earth's limb. Noiseless images were only modelled with
a solar elevation of 33.8 degrees, since the impact of noise was already modelled more thoroughly by varying the solar
elevation. The off nadir pointing simulations were only carried out for the RGB and NIR and RGB and NIR modified
images.
The following table summarizes the simulated images.
Table 5: Summary of the simulated iSIM90-12U images used for the assessment of the MANTIS commercial applications.
Pointing
Solar elevation
Noise
PAN
RGB+NIR
RGB+NIR modified
nadir
33.8
no
yes
yes
yes
nadir
33.8, 10, 60
yes
yes
yes
yes
Off nadir 10,30,50 deg
33.8
no
no
yes
yes
Proc. of SPIE Vol. 11505 1150507-16
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
The steps outlined above inevitably lead to an image that is degraded with respect to the input image but provides an
accurate model of an actual iSIM90-12U image sequence as obtained in the observational strategy implemented by
Satlantis in its iSIM camera concept. The resulting set of images was then run through Satlantis image post-processing
algorithm aimed to, both, recuperate lost spatial information and reduce noise in the so-called super-resolution process.
As explained before, this process relies upon a series of images observing a common scene but with relative spatial offsets
to each other. This was reproduced by taking a simulated iSIM90-12U image and dithering it by applying random sub-
pixel x/y shifts to the image. An example of such model images is shown in Figure 21.
Figure 21: A simulated iSIM90-12U image used for assessment of the MANTIS commercial applications.
Terrabotics assessed the detection and classification accuracy of a range of oil and gas target features in the simulated
iSIM90-12U images. The assessment used Terrabotics’ proprietary detection and classification workflows broadly based
on Convolution Neural Networks (CNNs). The effects of a decreasing signal-to-noise ratio and spatial resolution were
measured. Terrabotics determined that at a spatial resolution of 2.5m and below, and with an SNR of 55 or more, 80% of
all target features were detectable, as shown in Figure 22. Below these thresholds, larger features were still detected.
However, the detection rate of smaller features rapidly decreased.
Figure 22: Proportion of changed features detected by Terrabotics’ change detection algorithm, as a function of SNR and raw image
spatial resolution. The grey shaded region represents algorithm performance below the acceptable performance threshold. Vertical
dashed lines indicate the parameter values at which acceptable performance is reached. Note that SNR→∞ is the case with no added
noise.
Proc. of SPIE Vol. 11505 1150507-17
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
5. CONCLUSION AND FUTURE WORK
The paper presented has focused primarily on the iSIM90-12U optical payload and its constituent key innovations which
are developed by Satlantis in the context of the MANTIS mission. The technical discussion also presents an overview of
the mission aims and architecture, as well as the 12U platform developed by Open Cosmos. It also describes how
Terrabotics will carry out further processing and analysis of data to create added/value products (Level 2+) to serve existing
and future clients in the oil and gas sector.
MANTIS which is funded under the UK Space Agency contribution to the ESA’s InCubed program is a revolution, which
is designed to provide low-latency and targeted imagery tailored to the data needs of the oil and gas sector. This is achieved
through the implementation of an advanced very high resolution native multispectral imager developed by satlantis, which
is amalgamated to a new generation of CubeSat developed and operated by Open Cosmos.
The implementation of advanced technologies in the iSIM90-12U, in areas such mechanical, Optical, super resolution and
multi-specialty will provide an optical payload without precedent for the MANTIS mission.
By means of the 12U platform for the MANTIS mission, Open Cosmos is building upon the capabilities developed in the
design, manufacture, test and operation of its smaller 3U platform. As part of this mission Open Cosmos will further
enhance the capabilities of its mission control software
Through the use of the satellite imagery provided by the MANTIS mission, Terrabotics is seeking to build on their flagship
PADS™ product to further address specific use cases demanded by end-users. Through the Energy SCOUT project, part
of the Integrated Applications Programme co-sponsored by ESA [4], Terrabotics are currently developing the data
pipelines necessary to apply future MANTIS imagery to identified end-user needs.
It is envisioned that the MANTIS satellite will be the first of an aggregated constellation where customers will have access
to diverse types and volumes of information depending on the number of satellites contributed to the constellation. This
will enable organizations of all sizes and sectors to not only leverage their own space infrastructure but also benefit from
additional datasets and services from satellites that Open Cosmos manages and operates for others.
From the current state of the MANTIS mission to its completion, future steps will include but are not limited to, design
verification and optimization, manufacture, assembly, integration and test of the iSIM-90 12U at both qualification and
flight levels. Once iSIM90-12U FM has been coupled to the Flight 12U Platform, it is forecast the launch will be
undertaken in 2021.
REFERENCES
[1] Pastena M., Tossaint M., Regan A., Castorina M., Mathieu P., Rosello J., Gabriele A., Melega N. “Overview of
ESA’s Earth Observation upcoming small satellites missions” AIAA/USU Conference on Small Satellites,
Logan UT, August 2020
[2] The CubeSat Program, Cal Poly SLO, 6U CubeSat Design Specification Rev. 1.0, 2018/06/07 [Online available
at]:https://static1.squarespace.com/static/5418c831e4b0fa4ecac1bacd/t/5b75dfcd70a6adbee5908fd9/153445166
4215/6U_CDS_2018-06-07_rev_1.0.pdf
[3] Earth images, Product acquired by Worldview-3 (resolution 0.31m), [Online available at]:
https://earthimages.geocento.com/#product:products=2b60e8ae94459a75ad08129c0de5001a&observations=13
47367
[4] ARTES IAP Development Project, Energy SCOUT, 2020, [Online available at]:
https://business.esa.int/projects/energy-scout
Proc. of SPIE Vol. 11505 1150507-18
Downloaded From: https://www.spiedigitallibrary.org/conference-proceedings-of-spie on 26 Aug 2020
Terms of Use: https://www.spiedigitallibrary.org/terms-of-use
