uRTU - Micro Remote Terminal Unit

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The product is part of the spacecraft platform and payload architecture. The combination of dedicated Fuse Boxes and µRTUs has helped reduce harness mass on the Electra Platform by 400 kg by distributing smaller connecting units to be close to the equipment they serve, hereby significantly reducing the length of dedicated cabling. The product can be scaled according to different satellite needs, as it is designed using a modular concept. For the satellite the prime will choose the uRTU module configuration best suited to the specific need.


As the primary objective with this project is to reduce overall spacecraft mass, the unit itself is restricted to a rather tight mass budget – especially the amount of functionality taken into consideration.

Also the power dissipation in the unit requires attention, due to its relatively small footprint on the satellite structure.


Mass reduction of spacecraft, and thereby reduced expenses of launching equipment into space. This is done with a product that does not undermine reliability or flexibility of the solutions required for the individual satellites in which the product is installed. 


The four different module types contains the following functionalities: 

  • Core Module with HPC matrix driver (CMH)

Contains Auxiliary Power Supply and µRTU controller to support any of the other modules. Performs Analog TM acquisitioning and contains a HPC 8x8 matrix driver. 

  • Telemetry Acquisition Module (TAM)

Contains a Command and Telemetry Interface for communication with CMH module. 132 TM acquisition inputs, 12 precision calibration sources and 5V switchable outputs 

  • Heater Distribution Module (HDM)

CM/TM Interface for communication with CMH module. High-side heater switches and low-side group switches. 

  • Attitude Control Module (ACM)

CM/TM Interface for communication with CMH module. Auxiliary Power Supply as additional power is needed for the 28V distribution outputs, Magnetorquer Drivers and the Reaction Wheel Interfaces on the modules. Also contains Magnetometer supplies. 

Theses module types can be combined in a configuration with a very high degree of flexibility.

System Architecture

A µRTU is a non-redundant unit with external cross strapping capability; redundancy can therefore easily be obtained by having two µRTUs side by side.

A µRTU may contain just a single Core module, or when additional functionality is needed, the µRTU can be extended by attaching Interface modules to the Core module. The Core Module manages all internal control of the µRTU and act as a master on internal command and telemetry busses, while the Interface modules act as slaves. The interconnection between the µRTU modules are routed via a simple Backplane connector by one-to-one connections.

The µRTU assembly has the backplane mounted flat on the spacecraft panel with the modules plugged in vertically on top of the backplane. To ensure a solid assembly each module is locked to its neighbouring modules. All modules are mechanically identical, which means all modules can be mounted next to any other module. 


Phase1 consists of:

  • Kick Off (Sep. 2016)
  • PQSR (Jun. 2017)
  • PDR (Nov 2017)
  • EM phase (Oct. 2017 – Feb. 2018)
  • EQM phase (Jan. 2018 – Sep 2020)

Phase 2 consists of:

  • CDR (Oct. 2018)

FM phase (May. 2020 – Nov. 2021) (Not within scope of this ARTES project)

Current status

The design phase has been completed. EQSR, PDR, CDR is completed.

EM and EQM units have been delivered. In the frame of other projects RTU FM units have been delivered - the design is quite mature.

Prime Contractor