by Historically most space mission systems have used a single spacecraft designed to independently complete an entire mission. Be it a weather satellite or a manned module like Apollo, almost every spacecraft has been deployed and carried out its one-time mission completely alone.
But today, space industry organizations are exploring missions with many satellites working together. For example, SpaceX’s Starlink constellation includes thousands of satellites. And new spacecraft may have the ability to link up or rendezvous with other satellites in orbit for repairs or refueling.
Some of these spacecraft are already operational and serving customers, such as Northrop Grumman’s mission extension vehicle. This orbital craft gave birth to multiple communication satellites.
These new design options and on-orbit capabilities make space missions look more like large logistics operations on Earth.
We are researchers who have studied the space industry for years. We studied how the space sector could learn lessons from companies like Amazon or FedEx in managing complex fleets and coordinating operations.
Lessons from the land transport network
Space mission designers plan their routes to deliver their payloads to the Moon or Mars, or orbit efficiently within a set of cost, timeline and resource constraints. But when they need to coordinate multiple space vehicles working together, route planning can get complicated.
Ground logistics companies solve similar problems every day and transport goods and commodities around the globe. Therefore, researchers can study how these companies manage their logistics to help space companies and agencies learn how to successfully plan their mission operations.
One study funded by NASA in the early 2000s had an idea to simulate space logistics operations. These researchers viewed orbits or planets as cities and the corridors connecting them as avenues. They also looked at the payload, consumables, fuel and other items to be carried as commodities.
This approach helped them reframe the space mission problem as a commodity flow problem – a type of problem that ground logistics companies work on all the time.
Lessons from land logistics infrastructure
New capabilities to refuel and repair spacecraft in orbit create new opportunities as well as challenges.
That is, space operators don’t usually know which other satellite will fail or when that will happen. For these new technologies to be useful, space mission designers would have to come up with an infrastructure system. That could be like a fleet of service vehicles and depots in space that respond quickly to any unpredictable events.
Fortunately, space mission designers can learn from operations on the ground. City planners and emergency response organizations consider these types of challenges when deciding where to locate hospitals or fire departments. They also consider the ability of these facilities to respond to unpredictable calls.
We can draw an analogy between the design of a ground logistics system and the design of an in-space servicing system. In this way, researchers can leverage theories developed for ground logistics to improve space mission design practice.
One study published in November 2020 developed a framework for servicing spacecraft in orbit using what logistics experts call space queuing theory. Researchers often use this modeling theory to analyze the performance of ground logistics systems.
Lessons from land warehouse management
In the past, individual spacecraft carried out their missions independently, so if a satellite failed, its mission engineers had to develop and launch a replacement.
Now, for missions with multiple satellites, such as the Iridium satellite constellation, operators often keep one or more spares in orbit.
This becomes complicated for constellations consisting of hundreds or thousands of spacecraft. Mission designers want to make sure they have enough spare satellites in orbit so they don’t have to disrupt the mission if one breaks. But sending too many additional satellites is expensive.
When dealing with these types of large constellations, mission designers can learn from the methods used by Amazon and other terrestrial companies to manage their warehouses. Amazon places these warehouses in specific locations and stocks them with certain items to ensure that deliveries are handled efficiently.
On-the-ground inventory management theories can inform how space companies approach these challenges.
A study published in November 2019 developed an approach that space companies could use to manage their spares strategies. This approach can help them decide where in orbit to allocate their additional satellites to meet their needs and minimize any service disruptions.
International dimensions
Spacecraft operate in a complex and rapidly changing environment. Operators need to know where other missions are operating and what rules they should follow when refueling or repairing in space. In space, however, no one has yet defined these rules.
There are clear rules of the road for ships, aircraft and land vehicles to follow when interacting with other vehicles. For example, civilian ships and aircraft must share their location with other vehicles and officials to help manage traffic.
Some researchers are examining what similar rules might look like for space. One study examined how developing rules based on spacecraft size, age or other characteristics could help future space operations run more smoothly. For example, one rule might be that the most recently launched spacecraft should be responsible for maneuvering when another craft is in its path.
With more satellites and spacecraft being launched now than ever before, companies and government agencies will need new technologies and policies to coordinate them. As space activity becomes more complex, researchers can continue to apply what they’ve learned on the ground to new missions in space.
This article is republished from The Conversation, a non-profit, independent news organization that brings you reliable facts and analysis to help you make sense of our complex world. Written by: Koki Ho, Georgia Institute of Technology and Mariel Borowitz, Georgia Institute of Technology
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Koki Ho receives funding from NASA, AFRL, NSF, and industry. It is affiliated with the American Institute of Aeronautics and Astronautics (AIAA) and the Consortium for Space Mobility and In-Space Services, Assembly, and Manufacturing Capabilities (COSMIC).
Mariel Borowitz has received funding from the National Aeronautics and Space Administration, the National Science Foundation, and the US Department of Defense. In addition to her work at Georgia Tech, she is currently affiliated with the US Commercial Space Office. However, the opinions presented here are her own and do not reflect any organization.
