If space is to become a truly circular domain, it won’t happen by chasing down debris with nets or lasers — it will happen upstream, in design choices. One of the most compelling — and most elusive — of those choices is modularity.
At its core, modularity means designing satellites not as sealed, single-purpose machines, but as systems of swappable, replaceable, and upgradable parts. If something breaks, you swap the part. If technology improves, you upgrade a module. If the core bus still works but the payload doesn’t — you don’t throw the whole thing away.
This sounds like common sense — especially from a circular economy perspective. So why isn’t it the norm?
Why Aren’t Satellites Already Modular?
The truth is that space systems haven’t been optimised for reuse — they’ve been optimised for reliability, cost-efficiency, and survivability in harsh environments.
In satellite design, every gram matters. Every interface or connection adds mass and risk. Redundancy is achieved not by making systems modular, but by doubling up or overengineering critical components. And historically, replacing hardware in orbit wasn’t an option — so there was no point designing for it.
As commercial smallsats and constellations emerged, the logic didn’t shift. In fact, it became more rigid. To launch thousands of satellites cheaply, companies opted for highly integrated, purpose-built designs. The priority was rapid manufacturing, standard form factors, and low unit costs — not repairability.
In this environment, modularity came to be seen as a nice idea with too many drawbacks:
- Extra connectors = more failure points
- Standardised modules = design constraints
- Interchangeability = added mass and complexity
As a result, today’s orbital infrastructure is mostly monolithic — with each satellite expected to perform for a set lifespan and then deorbit, fail, or drift.
What Could Change?
Despite these challenges, modularity is not a dead idea. In fact, it’s starting to resurface — for three reasons.
First, in-orbit servicing is becoming more viable. If a robotic arm can refuel a satellite, it could eventually swap out a component. But only if the satellite is designed to allow that.
Second, launch costs have fallen dramatically. With cheaper access to space, the historical obsession with mass efficiency is loosening. A bit of extra structure or redundancy for modularity might now be worth the trade-off.
Third, there’s growing awareness — both commercially and politically — that wasteful design cannot continue indefinitely. If circularity is to be achieved, satellites need to become more like infrastructure — reusable, maintainable, and upgradeable.
Some programmes are already pointing the way. Airbus’ Arrow platform, DARPA’s Blackjack programme, and Lockheed’s LM series all explore modular or reconfigurable designs. Standardised satellite buses, swappable payload pods, and serviceable ports are slowly becoming more common — particularly for larger systems.
But these are still early efforts. For modularity to scale, the underlying economics and expectations need to shift.
What Does Modularity Enable?
Modular design is not just about aesthetics — it unlocks real circular value. It enables:
- Selective replacement: swap a failed component without scrapping the satellite
- In-orbit upgrades: add new capabilities to an old platform
- Flexible manufacturing: standard modules produced at scale, then customised
- Simplified recycling: easier disassembly = better material recovery
- Component re-use: salvage working subsystems from decommissioned craft
In short, it changes the lifecycle from use–discard to use–upgrade–reuse–recover. It also aligns with the growing trend of servicing spacecraft, which depend on physical access and compatibility.
A satellite built for modularity is a satellite built for options — and in space, options are invaluable.
The Role of Standards
One of the barriers to modularity is the lack of common standards. If every manufacturer designs proprietary buses, interfaces, and enclosures, interoperability becomes impossible.
This is where shared industry standards can have real power. Just as the CubeSat standard unlocked an entire class of small spacecraft by standardising dimensions and deployment, modularity could benefit from a shared satellite backplane, power/data interfaces, or payload module formats.
Efforts like the Space Sustainability Rating in policy, suggest growing appetite for this kind of coordination. But for now, most modularity remains in-house — tailored to single operator fleets.
If a circular economy is to emerge, we’ll likely need cross-sector agreement — and regulatory nudges — to encourage standardised modular approaches.
Limits, Trade-Offs and Mindsets
Modularity isn’t a panacea. Some spacecraft — especially cubesats and very small platforms — may never benefit from it. For them, the added complexity outweighs any gains. Likewise, missions in high-risk or short-duration environments may not justify the extra cost or mass. There’s also the risk of overdesign — building for upgradeability that never happens. If no servicing is ever performed, modularity simply becomes dead weight.
But these are not arguments against modularity — they’re arguments for using it strategically, where the economics, infrastructure, and mission profile justify it.
Perhaps the biggest challenge is not technical at all, but cultural. Most satellites today are built with a linear mindset: launch, operate, deorbit (or not). Modularity disrupts that — it invites planning for intervention, design for recovery, and long-term responsibility for assets that may outlast their first use.
It requires shifting the way we think about spacecraft — from disposable tools to maintainable infrastructure.
Reusability Starts with Design
Circularity in space doesn’t begin with retrieval. It begins with design that anticipates reuse. Modularity won’t solve everything — but it opens the door. It creates the technical precondition for repair, recovery, and refurbishment. Without it, every satellite is a one-way ticket. With it, we get choices — and in a domain as hostile and expensive as space, that’s a foundation worth building on.
We’re seeing the first signs of modularity and standardisation being taken up by the space industry. It’s time to encourage this and support those working on these advances to make sure they don’t fall foul of the trough of disillusionment.
