Given the needs discussed before, a solution capable of providing a broad picture of the different phenomena identified with adequate temporal and spatial scales is essential to tackle future challenges.

With the advent of the modern small satellites, in particular micro and nano satellites (i.e. less than 100 kg and less than 10 kg respectively), and the steep increase in launches in the last decade (close to 1000 nano satellites since 2013 and a staggering 390 to be launched the current year), there is a push to widely democratized access to space. However, in the case of a satellite with a radar altimeter, satisfying power and antenna size requirements will be the principal engineering and design challenges.

Still, there are concepts for performing radar altimetry using a small constellation (two to six 6U CubeSats) which conclude that a radar altimeter with 1 W available power would achieve a Sea Surface Height Anomaly (SSHA) Root-Mean-Square (RMS) errors of 12.5 cm at an 80% confidence level5. This accuracy improves with more nano satellites when compared to a single-spacecraft mission like Jason-3.

Therefore, repeated global measurements of sea surface height by a constellation of small satellites equipped with radar altimeters will provide significant gains in both the quantity and quality of spatial and temporal resolution needed to understand the influence of global climate trends on regional weather and climate related events (floods, drought, storms, etc.), as well as the cycles and trends in the global ocean-atmospheric system.

The envisioned integrated system, MAGAL, is a stepping-stone to further democratize access to space data, via the introduction of altimetry payloads in smaller than conventional satellites, and therefore speed up the exploration and valorization of the Space/Earth economic and scientific synergies. Furthermore, MAGAL will promote the diversification of platform and sensor types and characteristics, that the space sector should thrive for to be able to tackle global and sectorial challenges.

The advantages of such a system includes:

• Cost reduction by using small satellite platforms, when compared to conventional missions
• Potential to use economies of scale effects by designing and developing multiple similar spacecraft, instead of single platforms
• Exploration of synergies between different missions and assets, for example, through developing coordinated missions with in-situ assets
• Increased temporal and spatial coverage and decrease of single point failures, only possible by using a constellation

To achieve the ambitious goals stated above and maximize the timeframe and budget of the project, MAGAL is structured to design and develop a proof-of-concept satellite with altimeter, whereby the payload can be tested and demonstrated using an Unmanned Aerial Vehicle (UAV). This will lay the essential ground-work required to subsequently enter more confidently, post MAGAL, the full production and launch into space of this new design of satellite and operational constellation coupled with the information and analysis center.

The relevant constituent components of MAGAL that were selected to be design and developed during the current project, are:

1. Altimeter payload, including antennas
2. Information and Analysis Center
3. Constellation
4. Satellite platform

Key payload development aspects will be addressed in MAGAL, in particular the challenges of the miniaturization of the altimeter and complementary systems such as antenna designs. Important factors such as power requirements, power budget and heat dissipation which can impact on the platform design and the attainment of the MAGAL objectives will also be taken into account.

The payload developed in MAGAL, after extensive ground tests, will be assembled and integrated in an existing UAV with the intent to demonstrate the unique payload capabilities in a relevant environment that can validate the functioning of the payload but chiefly of the software and algorithm to process the data acquired in such an environment. Therefore, the payload demonstration on UAVs can be performed as an intermediary step before final qualification and deployment to space whilst also adding value to activities in the MAGAL project timeframe. To this end, the calibration and demonstration activities through the use of UAVs will be performed, preferably around the Azores islands, so that traditionally difficult areas to be monitored from space can be explored and later used in conjunction with the satellite data later obtained of the region under concern.

Another important aspect of MAGAL is the development and implementation of the Information and Analysis Center. This center will ensure the use of the MAGAL project outcomes and the possible combinations with other constellations of satellites for maximum leverage, making it effective and relevant to industry and society in today’s information and data driven age. Data collection, mining, interpretation through innovative visualization techniques, algorithms, super-positioning and the comparison of data sources will be key areas of concern. The software will be developed in terms of front-end and back-end to ensure consistency of techniques, whilst consideration will be given to scalability and hardware requirements for sound implementation of the defined architecture. The ability to make the best use of various multiple data sources with the application of other techniques such as Artificial Intelligence, among others, will ensure that this center will further maximize the outcomes of MAGAL and the constellation envisaged for many years to come.

Within the constellation design, such aspects as constellation parameters, including key spatial and temporal coverage, will be developed and defined in parallel with the satellite platform design characteristics, to enable the orderly future deployment of a constellation. All mission programmatic aspects that have an effect on satellite platform design as well as the Information and Analysis Center will be taken into account. The possible interactions and dependencies between satellites and the smart relay of information, redundancy and complementarity of sources will be addressed. The desired replenishment rates of the constellation, minimum quorum, influence of drag and orbit parameters using tailored algorithms and data analysis will also be considered.

Finally, the complete satellite platform design will use sound systems engineering practices to ensure a coherent design that can comply with both payload and constellation mission requirements. A complete integrated platform design, that corresponds to the specifications and requirements, will be taken up to Critical Design Review (CDR) stage. The disciplines of structures, propulsion and avionics design will be furthered to achieve the correct balance between the use of specialized and off-the-shelf components, whilst ensuring the recourse of advanced materials and manufacturing techniques, such as ALM, in the design for future production. Reasonable and foreseeable margins required for eventual manufacture and deployment will be taken into account.

MAGAL is an innovative concept of Altimetry Radar and its current settled baseline architecture and requirements were defined having as primary goal the following “Use Cases”:

• MAGAL “Use Cases” and Applications:
  • Sea Surface Topography
  • Eddy Detection and Tracking
  • Marine Debris Monitoring
  • Inland Water Levels

From these “Use Cases” and market analysis, our primary focus on services and products will focus on the following

• Business Cases:
  • Fisheries
  • Marine protected areas fulfilling European requirements directives
  • Natural disasters

MAGAL Constellation will improve the current temporal sampling from 10 days to 5 days, keeping the current spatial temporal resolution, measurements accuracies and resolutions. For that, MAGAL satellites will ensure a precise location and orbit maintenance. Beyond that, MAGAL tracks will be interleaved with those of operational satellite altimetry missions to allow data aggregation.

The MAGAL Constellation is a future constellation of small satellites carrying radar altimeters that aims to improve the understanding of ocean circulation variability in local, regional, and global scales through improving the spatiotemporal resolution of sea surface topography measurements. The measurements provided by MAGAL are expected to augment those from the operational Radio Altimetry missions to improve the collective data products with an enhanced data set over the open ocean, while also targeting the coastal processes.

To achieve these goals, MAGAL Constellation is being designed based in six CubeSat, no larger than 24U, flying into a single sun-synchronous Exact Repeat Mission orbit with 97.4º inclination and at a ~500 km altitude, providing full coverage with a 5-day repetition cycle and distance between adjacent tracks of ~88 km at the Equator.

A Data Analysis Center (DAC) is also being developed for data storage and processing, which will also include data from multiple sources (e.g., meteorology) to produce scientific and commercial information. The DAC front-end layer will also allow the display of the data in various graphical interfaces.

MAGAL is a proof of concept, can an innovative technological concept such as a constellation of small satellites with radar altimeters, not yet implemented to date, contribute to the future of Satellite Altimetry?

From our studies and analysis, we are convinced YES.

MAGAL project was, in first place, a proof of concept of an innovative technological concept.

MAGAL project established its mission requirements from the science objectives and builds its architecture and design on top of them. The required payloads to be included in the MAGAL satellite were primarily searched on market-available COTS, and only whenever we could not identify one fulfilling our needs did, we go for custom development. In this field, MAGAL developed the following custom innovate solutions:

• A small and compact Radar Altimeter, using FMCW technology at 13GHz, with budgets compatible with CubeSat & small satellites.
  • Full functional operational prototype developed, manufactured and tested at ground level. Tests in altitude will be performed by the consortium.
• A Data Analysis Centre (DAC) for data storage and processing. This centre shall also include data from multiple sources (e.g., meteorology) to produce scientific and commercial information. The DAC front-end layer will also allow the display of the data in various graphical interfaces.
  • DAC developed and implemented using Copernicus, Sentinel, data.
  • Simulation tools created to emulate radar altimeter performance and data, as well as MAGAL orbit mechanics. They can be now used to continue develop DAC and implement / validate the processes and algorithms of its services and products.

As main open point of the project MAGAL is its radar altimeter deployable antenna. It was identified that there are no deployable antennas for operating the radar altimeter, at Ku band. Due to budgets and time limitations this payload is not frozen. However, several contacts were performed, and some companies were identified as interested in developing this equipment within fulfilling our requirements.

These custom developments were also identified has having large value in the market as spinoff’s assets of the project.

MAGAL project ends at CDR level for its critical payloads and developments. All its other payloads are between PDR and CDR. All COTS to manufacturer MAGAL are identified and selected, except deployable antenna, which as to be a new development.

It’s time to now market requires a demonstration with a deployment of at least one MAGAL satellite. We are looking for funding to proof the concept. Its consolidation, manufacturing and deployment shall take around 2.5 years.

MAGAL key improvement to radar altimetry is its time resolution of 5 days repetition cycle, with all the other parameters identical. Also, being in “New Space” domain, all costs are much lower.

Concluding, MAGAL project is and end-to-end solution that redefines Radar Altimetry for global oceans monitoring using a new approach based on a constellation of six small satellites and an innovative radar altimeter, that will improve the understanding of ocean circulation variability on local, regional, and global scales by improving the spatiotemporal resolution of sea surface topography measurements, all aligned with the European “New Space” agenda and UN Sustainable Development Goals. MAGAL project is the first proof of concept of such an approach. MAGAL can be the cornerstone for ocean monitoring, bringing it to a more cost-effective Earth Observation due to its reduced production, launch and operational costs, making more frequent and spread ocean data available.