Engineering a Safer and a More Sustainable Space Environment with Ansys STK

Artistic impression of the ClearSpace-1 servicer | © ClearSpace

The space environment is facing unprecedented congestion (as of April 2026: ESA - Space debris by the numbers):

• About 25920 satellites launched throughout 7,210 rocket launches since the start of the Space exploration in 1957
• About 17,610 satellites currently in orbit among which 15200 are still functioning
• About 44,870 regularly tracked objects and maintained in catalogues.

This accumulation of debris and the exponential rise of satellite mega constellations increase collision risks and contribute to the potential onset of the Kessler Syndrome. Mission simulations are key to reducing the costs associated with failures caused by poor risk assessment.

ClearSpace: Contributing to a More Sustainable  Space Environment 

ClearSpace is a Swiss space technology company founded in 2018 as a spin-off from the École Polytechnique Fédérale de Lausanne (EPFL). It was established to further develop and commercialize technologies originating from the pioneering “CleanSpace One” initiative.

The company focuses on in-orbit servicing and space debris mitigation, addressing a growing challenge for the long-term sustainability of space activities. In 2019, the European Space Agency (ESA) selected ClearSpace to contribute to the ClearSpace 1 mission, an early effort to demonstrate the removal of space debris as a commercial service. The programme marked an important evolution in how such missions can be procured and delivered within the European space ecosystem.

Over time, the programme structure has evolved, and today ClearSpace contributes key technologies to the mission, including the robotic capture system, in close collaboration with the industrial prime contractor, OHB. The mission is also supported by a range of institutional and commercial partners, including mission elite partner OMEGA, whose contribution reflects growing cross-sector engagement in advancing space sustainability.

ClearSpace has also expanded beyond its original base in Renens, Switzerland, establishing an international presence with offices in the United Kingdom, Germany, and Luxembourg. Through its activities, the company supports institutional and commercial efforts aimed at enabling more sustainable and responsible operations in space.

Space congestion | © ClearSpace

The Need for High-Level Simulations of Space Missions

The complexity of in orbit servicing drives the need for accurate, physics based simulation tools. ClearSpace’s engineering teams must model:

• Long term orbit propagation under varying solar cycle conditions
• High risk proximity operations with strict attitude constraints
• Power generation limitations due to shadowing

• Orbital perturbations affecting both servicer and client spacecraft

Without reliable simulations, missions risk of incorrect approach trajectories, unexpected power losses, or operational failures. The absence of servicing infrastructure in orbit further increases engineering and operational uncertainty. Hence, Ansys STK helps engineers to model complex systems inside a realistic and time-dynamic three-dimensional simulation to analyze the influence of various parameters on the orbital propagation.

Modeling Complex Systems with Ansys STK, CADFEM, and tukom

Consequently, ClearSpace has adopted Ansys STK as its central digital platform for mission engineering to address the challenges outlined above. Joining the effort are tukom GmbH, a specialist in technologies for telemetry, aerospace, and defense, and CADFEM, with its experienced experts in simulating a wide range of physical phenomena using Ansys. 

PRELUDE | © ClearSpace

Mission Completed: Technical Improvements, Reduction of Risks and Costs

Although no quantified key performance indicators were provided, ClearSpace reports several substantial technical and economic improvements thanks to the integration of Ansys STK, which significantly reduces risks and uncertainties.

Technical Improvements

• STK enables more accurate long term propagation of Orbits:
  Orbit propagation involves predicting the future position and velocity of a satellite based on its current state. Accurate propagation requires complex Earth gravity models, including the influences of the Moon and Sun, as well as advanced atmospheric models, which are essential below 700 km altitude. STK integrates all these elements, offering ClearSpace engineers a much higher level of confidence than simple in-house tools.

• Better prediction of orbital decay during varying solar activity:
  Ansys STK atmospheric models can be easily adjusted according to solar activity. Using predicted minimum and maximum values provides a more accurate range of future trajectories than less comprehensive models. Moreover, ClearSpace could import higher-fidelity atmospheric model from external sources it in STK and use it in their simulation.

• Enhanced modeling of attitude constraints and proximity operations:
  STK allows different possibilities of modelling vehicle attitude and the constraints associated with it. It can be an attitude file, simple VB script describing the attitude or external attitude models such as models described in tools like MATLAB, Python, etc. which, provided with an open API, can be imported in STK. There are over 40 Rendezvous and Proximity (RPO) sequences available with STK Astrogator which helps users with their proximity operations’ design that could ease ClearSpace’s mission design.

• Improved understanding of shadowing effects on power Generation:
  With a high-fidelity orbit propagation and strong attitude simulation, the amount of solar power hitting the panel surfaces can be estimated with certainty. Connecting STK with other Ansys tools such as Ansys Discovery, the shadow cast on solar panels during close maneuvers due to the geometry of objects could be predicted, improving the overall mission planning.

Risk Reduction and Better Economic Prediction

• Lower operational uncertainty:
  Using Ansys STK is essential for gaining valuable insights into what could happen in orbit. Early risk identification decreases and mitigates uncertainties and their consequences, instead of discovering them in orbit when it might be too late.

• Avoidance of costly mission failures:
  Uncovering the many uncertainties through the simulations of so many aspects of the mission genuinely reduces the remaining risks for the mission and, consequently, the costs related to unexpected failures.

ClearSpace Phoenix Breathing New Life into Space  | © ClearSpace

Future Perspectives

ClearSpace aims to solidify its role as the “roadside assistant to all space assets,” expanding its portfolio toward multi mission servicing platforms for:

• Autonomous capture of uncooperative objects
• Life extension capabilities for commercial satellites
• Orbital transport and repositioning
• Modular in orbit repair and refueling

ClearSpace-1: Removal of an ESA-owned object Commissioned by the European Space Agency (ESA) Supported by mission elite partner Omega. | © ClearSpace