Managing Constellations: A Flight Dynamics Perspective

December 13, 2021

While the world shows signs of slowly emerging from a global pandemic, satellite operations in Low Earth Orbit (LEO) continue to change rapidly. In the first half of 2021,  over 1,000 primarily LEO satellites  have launched. Federal Communications Commission (FCC) filings and market research indicate that thousands of LEO satellites could be in orbit by 2030. This exponential growth is dominated by a few large constellations, with a handful of operators flying more than 1,000 satellite constellations. In addition, the global market is evolving as multiple companies work toward smaller constellations of five to 50 satellites, with different needs at that scale. It is in this context that a.i. solutions sat down with Andrew Werner, Director of Space Products at the company. 

What role does a.i. solutions play in the modernization of satellite operations? 

a.i. solutions is an engineering services company specializing in satellite flight dynamics (also known as orbital mechanics or astrodynamics) — determining where your satellite has been, knowing where it will be considering the various forces acting on it, and planning maneuvers to meet the satellite’s objectives — all while maintaining proper orientation, meeting communication and sensor coverage needs, and avoiding debris and other satellites. 

a.i. solutions 25th anniversary logo

In 2021, we celebrate 25 years of providing flight dynamics expertise and software to civil, military, commercial, international, and academic customers. Across mission planning, launch, early mission, on-orbit, and disposal [phases], a.i. solutions has enabled the success of hundreds of satellites, including the International Space Station (ISS), GPS, Landsat, and the Geostationary Operational Environmental Satellite (GOES). We also develop FreeFlyer®, the most powerful, flexible, and operationally verified and validated flight dynamics COTS [Commercial off-the-shelf] software on the market. FreeFlyer allows engineers to customize space mission design, analysis, and operations functions to meet their specific needs. In addition to our trusted and proven space software, customers can access our world-class FreeFlyer engineering support team, all with flexible licensing, resulting in the best value on the market. 

We’re seeing more and more LEO constellations. How can COTS providers meet the increasing demands of constellations? 

screen capture of FreeFlyer software demonstrating space situational awareness

FreeFlyer logo

When operating a satellite, flight dynamics tasks need to be performed at certain intervals, such as planning an upcoming maneuver or determining possible contact times with an antenna on the Earth. It is common for FreeFlyer-based operations to automate these tasks and make the resulting data products available. With multiple satellites, the processing time of these operations increases, in some cases exponentially, for tasks such as intra-constellation Collision Avoidance (CA). Ground systems need to be able to scale, and FreeFlyer is architected to accommodate that. FreeFlyer can distribute an entire constellation’s flight dynamics tasks across virtual machines or cloud instances, generating products in parallel to minimize overall run time. Our clients with current or planned constellation operations tell us FreeFlyer provides what they’re looking for — flexible interfacing and scalability to meet their flight dynamics needs today and in the future. 

Constellation providers often plan to start with a few prototype spacecraft and grow to 50 or more satellites. In these cases, automation and flexibility must go hand and hand. Many providers want a hands-on operator for the first few satellites to gain experience before transitioning routine processes to automation. We have also found that constellation providers need the flexibility to modify automation workflows over time, re-run specific tasks [if needed], and run across different hardware configurations — such as single machine, client/server architecture, or at scale across virtual machines or cloud instances. 

a.i. solutions developed our Meridian software, which is powered by FreeFlyer, with these needs in mind. It meets most standard LEO or GEO flight dynamics requirements with minimal configuration. Automated workflows generate routine productsmaneuver plans, contact times, ephemerides, etc. Operators can view automated tasking and manually intervene

Meridian Ground Systems dashboard

Meridian Ground Systems logo

if necessary, enabling them to manage multiple spacecraft from a single modern interface. regularly develops new versions of our Meridian and FreeFlyer products with increased functionality.

How does your software scale to support operations of large constellations with thousands or tens of thousands of satellites? 

FreeFlyer’s flexibility and power makes it uniquely suited to support analysis and operations for large constellations, in which automation and processing speed is of increased importance. It is not enough to automate routine operations, as even infrequent events at this scale can result in a significant workforce if they require operator intervention. For example, an a.i. solutions engineer uses FreeFlyer to analyze ascent and on-orbit operations of the Starlink constellation automatically. Orbit data is ingested for each satellite as it becomes available, running a series of analyses that reveal when a spacecraft deviates from its expected behavior, alerting the engineer. By only analyzing anomalous behavior, we minimize staffing, allowing us to focus on potential risks to other satellites. 

Large constellations have a dozen or more satellites spread out across a single orbit plane. These orbit planes are natural grouping mechanisms for performing analysis and operations at scale. A single cloud instance of FreeFlyer can quickly perform the necessary flight dynamics tasks, such as planning maneuvers to maintain proper satellite spacing within the plane. Conjunctions are possible where orbit planes overlap, and FreeFlyer can assess the risk at these crossings with realistic uncertainty in position and velocity. Different avoidance strategies can be rapidly devised and tested to minimize and effectively plan for this risk.  

Click here to watch the “Cloud Architecture for Constellation Operations” video where Stephan Novak, a FreeFlyer developer, demonstrates how FreeFlyer can be included in a cloud architecture (CA) flight dynamics workflow

FreeFlyer software demonstrating the alignment of constellations of satellites.

Another type of constellation on the rise is a cluster (or formation) — a small number of cooperative satellites in close proximity. What unique challenges are involved with clusters? 

The geometric relationship between cluster members — their spacing, interactions, and overall cluster shape — is extremely complex and must be continually evaluated and predicted in operations. Our efforts with NASA’s record-setting Magnetospheric Multiscale formation found traditional CA methods were not valid for close-flying, low-relative velocity missions. We developed new methodologies using Graphics Processing Unit technology to obtain trusted CA results on operational timelines. Building on this, we developed a cluster quality factor metric to statistically evaluate how mission performance will degrade or improve over time, maneuvering satellites within the cluster as needed. 

FreeFlyer software demonstrating space situational awareness between two individual satellites

There are concerns about how these large constellations will impact space safety. How does a.i. solutions envision the future of space traffic management? 

a.i. solutions is committed to making space safe. FreeFlyer is currently used for CA on dozens of missions, most notably the ISS. While FreeFlyer could perform CA for all Space Traffic Management as it moves from 18 SPCS to a civil agency, a.i. solutions supports the Open Architecture Data Repository (OADR) concept, an open marketplace with multiple competing solutions. FreeFlyer’s API enables cloud-based autonomous scripts to accomplish any portion of the CA analysis pipeline, depending on customer needs and choices. 

Additionally, a.i. solutions has developed a tool called ObsSIM that provides simulated physics-based space surveillance observations to support timely, efficient, and realistic testing, training, and real-time space exercises. ObsSIM uses FreeFlyer to provide simulated observations in the same formats as live data, allowing trainers to emulate an adverse condition, such as a breakup or collision, that may be infeasible to execute for an exercise or other training scenario. ObsSIM and tools like it can be the foundation for simulations that help operators train on the OADR environment.  


> View FreeFlyer Blog