Mission Programs

NGC Aerospace Ltd has provided the autonomous guidance, navigation and control software for four satellite missions currently successfully in operation and is preparing for other space missions that are in various phases of development.

Space Missions

A Leader in the Control of Space Vehicles

NGC Aerospace, as an international leader in the design of guidance, navigation and control software for space vehicles, has accumulated more than two decades of successful continuous flight operations on four different satellites: PROBA-1, PROBA-2, PROBA-V and Sentinel-3A.

NGC made a quantum leap in aerospace technology by creating a new generation of satellites that integrates for the first time on-board intelligence and autonomy in the operation of scientific and Earth-observation satellites, thereby increasing the reliability and the efficiency of the satellites while reducing their operating costs.

A Reputation for Practical Innovations

NGC Aerospace is at the origin of two major breakthroughs in the design and operation of satellites:

  • the migration of the navigation, guidance and control intelligence from the ground station to the on-board computer, thereby reducing the cost of operating the satellite;
  • the development of computer-aided, automated tools for the design and validation of the on-board software, thereby reducing the cost of software development.

A History of Successful Space Missions

NGC Aerospace has contributed its unique expertise in the following space programmes:

  • the PROBA satellites, demonstrating autonomy for space vehicles,
  • the Sentinel-3 satellite, an operational Earth-observation satellite,
  • the Lunar Lander mission, demonstrating safe and high-precision landing on the Moon.

The PROBA Satellites

The PRoject for On-Board Autonomy (PROBA) is an ESA technology-demonstration program aimed at the in-orbit validation of innovative space technologies, in particular aiming at the demonstration of on-board autonomy. The Guidance, Navigation and Control (GNC) software is at the heart of the intelligence of the PROBA spacecraft and is crucial to their high level of on-board autonomy.

NGC Aerospace has contributed its expertise to the realisation of three PROBA satellites currently in orbit. PROBA-1 was launched on 22 October 2001 on an Earth-observation mission aimed at the analysis of climatic changes. PROBA-2, a Sun-observation satellite, is studying the influence of the Sun activity on our environment since its launch on 2 November 2009. PROBA-V, for PROBA-Vegetation, was successfully launched in May 2013 to start its mission on the study of the natural evolution of the Earth’s vegetation. All three satellites are still successfully operating in space and provide valuable scientific data to scientists.


NGCAerospace has pioneered a new paradigm in both the design and the operation of spacecraft, starting with the PROBA-1 spacecraft launched in 2001 and still successfully operating today for an extended mission well beyond the design lifetime of 2 years. NGC was Verhaert Space’s (now QinetiQ Space) subcontractor for the development, implementation and validation of the autonomous attitude and orbit GNC software of the highly-autonomous and agile PROBA-1 spacecraft. PROBA-1 was the first European spacecraft with fully autonomous operations with little involvement from the ground control station. Also a first in the ESA context, the GNC flight software contributed by NGC was entirely designed, developed and validated using computer-aided software engineering (CASE) tools, including the automatic generation of the flight code.

The novel features contributed by NGC with the PROBA-1 spacecraft GNC software include but are not limited to:

  • gyro-less autonomous attitude determination with sensor delay recovery,
  • autonomous orbit determination with sensor delay recovery,
  • prediction of orbital events (e.g. eclipse entry/exit),
  • prediction of target and ground station flybys over the next 24 hours,
  • on-board generation of commanded attitude profiles including during imaging which requires taking 5 scans of the same target region at 1/5 of the nominal push-broom speed,
  • pointing to Earth and Sun without Earth and Sun sensors,
  • autonomous management of the total spacecraft angular momentum.

See PROBA-1 page on ESA website for additional details on the mission.


The PROBA-1 Satellite (© ESA, source)


NGC has again worked under Verhaert Space’s (now QinetiQ Space) leadership for the development, implementation and validation of the autonomous attitude and orbit GNC software for the PROBA-2 spacecraft. The PROBA-2 satellite began its space journey on 2 November 2009 to accomplish its dual mission of scientific discovery and technology demonstration. The 130 kg satellite was successfully placed on its sun-synchronous orbit at an altitude of 700 km. PROBA-2, which is the size of a large television and consumes the energy equivalent to a 60 Watt bulb, has four scientific experiments on board (two in the field of space weather and two for sun observation) as well as 17 technological innovations that will be validated in orbit.

In addition to re-using and improving the novel features included in the PROBA-1 GNC software and listed above, NGC contributed the following novel features in the PROBA-2 AOCS software:

  • 6 AOCS flight experiments including UKF based orbit and attitude determination, experimental 3-axis magnetic-only control law and autonomous on-board environmental perturbation torque estimation;
  • autonomous generation of the attitude profile for Sun observation including precise pointing to any user-commanded regions of the Sun and autonomous large-angle rotation about the payload line of sight four times per orbit in order to avoid star tracker blinding.

See PROBA-2 page on ESA website for additional details on the mission.


The PROBA-2 Satellite (© ESA – P. Carril 2009, source)


As subcontractor to QinetiQ Space, NGC developed, implemented and validated the autonomous attitude and orbit GNC software for the PROBA-V spacecraft. PROBA-V, for PROBA-Vegetation, extends the data collection from the Vegetation Instruments onboard the Spot-4 and Spot-5 satellites. Every second day, its three multi-spectral imaging telescopes cover the complete landmass of the Earth, gathering detailed information on the health of our planet, on its climate and on its vegetation. The vast amount of data to be gathered over the satellite’s 2.5-year orbital lifetime will serve in the monitoring of surface water, agricultural land, desertification and deforestation with the objective of securing the supply of food for future generations.

The 140-kg satellite, not larger than a cubic meter, is operated from a 820 km high, Sun-synchronous orbit which maintains a constant orientation with respect to the Sun, thus ensuring high-quality images. The multi-spectral cameras operate at a 100 m resolution with a 2250 km push-broom swath.

The novel features included in the PROBA-V AOCS software compared to PROBA-1 and PROBA-2 include:

  • high-efficiency prediction of sea and land flybys for autonomous on-board activation/deactivation of the payload over land/sea,
  • autonomous optimal Sun pointing manoeuvre,
  • autonomous geodetic pointing with optional yaw steering,
  • avoidance of reaction-wheel speed crossing zero during imaging using only 3 reaction wheels,
  • autonomous avoidance of forbidden attitude during large angle manoeuvres,
  • three-axis pointing magnetic safe mode.

See PROBA-V page on ESA website for additional details on the mission.

PROBA-V animation showing the autonomous activation/deactivation of the payload over land/sea (© ESA)


The PROBA-V Satellite (© ESA – P. Carril 2012, source)


NGC is also contributing its expertise in the fourth project of the PROBA series, PROBA-3. The satellite is currently in its development phase for a launch in 2017. Two PROBA-3 satellites are being designed: an Occulter satellite whose mission is to block the very intense light emission from the main solar disk and the Coronagraph, whose scientific mission is to align itself accurately with the Occulter and the sun in order to observe the sun corona. In addition to this scientific objective, PROBA-3 will also have the technological mission of demonstrating in orbit the formation flight of satellites. NGC is responsible for the spacecraft GNC (SC-GNC) software.

See PROBA-3 page on ESA website for additional details on the mission.

PROBA-3 Formation Flying Mission

PROBA-3 Formation Flying Mission (© ESA – P. Carril 2013, source)


NGC has been selected by the Prime contractor of the Sentinel-3 spacecraft to provide its expertise in the design and validation of the Attitude and Orbit Control System (AOCS) of the spacecraft. ESA Sentinels (Sentinel-1, Sentinel-2 and Sentinel-3) will be the first series of operational satellites to meet the Earth observation needs of the European Union-ESA Global Monitoring for Environment and Security (GMES) programme. The pair of Sentinel-3 satellites will provide global, frequent and near-real-time ocean, ice and land monitoring.  Sentinel-3A satellite was launched in February 2016.

At AOCS level, the main innovation consists in implementing in this operational mission a PROBA-like autonomy. In order to allow the PROBA technology transfer to Sentinel-3, NGC engineers have been responsible for the orbit navigation and attitude guidance functions as well as for the design and validation of the Normal Operation Mode (NOM) which is the mission mode. This project exemplifies the skills and competence of NGC in developing autonomous flight software. The Sentinel-3 AOCS software is designed and coded in MATLAB/Simulink. The AOCS functions are also automatically translated into C code for implementation within the on-board software.

See SENTINEL-3 page on ESA website for additional details on the mission.

Lunar Lander Mission

NGC’s involvement in ESA Lunar Lander mission Phase B has been threefold:

  • NGC was responsible, under a subcontract from the Prime contractor Astrium (now Airbus Space), for the Phase B development of the AOCS software of a Lunar Lander spacecraft. NGC has developed and validated a prototype AOCS software in MATLAB/Simulink responsible for controlling the lander attitude and delta-V manoeuvres starting from launcher separation in Earth orbit until initiation of the lunar descent orbit.
  • NGC was also a subcontractor responsible for the Phase B development of the Guidance, Control and Hazard Detection and Avoidance (HDA) systems for the autonomous descent & landing segment. NGC designed the reference descent & landing scenario, designed the software and validated it in end-to-end simulation environment. A noticeable innovation of this design is the fusion of camera and motion-compensated Lidar data in the assessment of surface hazards.
  • Finally, NGC supported the definition of system-level Lidar sensor requirements. Under a subcontract from Neptec Design Group, NGC supported trade-off studies to estimate overall sensor performance and the impact on system budgets of various sensor design parameters.

See Lunar Lander page on ESA website for additional details on the mission.