A reference index of the standards that move data between Earth and spacecraft, grouped by protocol layer.
Every standard in this reference exists because something in space went wrong — a frame lost in noise, a command that arrived twice, a link that vanished mid-pass — until someone designed the failure away. Each entry explains a protocol from that starting point: the situation that demanded it, not the section numbering of its spec.
The goal is intuition. A specification tells you what the fields are; these pages try to tell you why the fields exist — what each protocol protects, what it costs, and what breaks without it. After reading an entry, the spec should feel less like a wall of rules and more like the only shape the solution could have taken.
Most flying missions speak a blend. CCSDS dominates the framing and packet layers; ECSS prescribes the engineering practice around them; IETF owns the delay-tolerant parts that look Internet-shaped. The protocol stack is OSI-shaped but not OSI — a working model, not a theory.
Each entry stands alone — read it when a spec lands on your desk, or browse the stack layer by layer below. The reference is being written serially, so many pages currently hold a place rather than a text; the index is the full map of where it is headed. And when you want the longer story around a standard, the entry links to the Primer chapter where it first appears.
Turning intent into a wave that survives 400 million kilometres.
When radio runs out of spectrum, point a laser.
Knowing where the spacecraft is by listening to its echo.
Mathematics that lets a bit survive being half-erased.
Finding frames in noise, and bits inside frames.
Framing and verifying every uplinked command before the spacecraft acts on it.
Many onboard systems competing for one downlink.
Frames, segments, and the discipline of uplink.
What happens if a critical command never arrives.
Maximising throughput through a window measured in minutes.
One link layer to replace TM, TC, and AOS.
Short-range links between cooperating spacecraft.
An envelope for meaning on a shared channel.
Carrying IP, bundles, and the not-yet-invented.
Reliable transport for links measured in light-minutes.
Networks that exist only sometimes.
Publish/subscribe across a network that may sleep for hours.
Synchronising memory across intermittent links.
The service catalogue every European spacecraft speaks.
PUS, rewritten as a modern service framework.
Teaching the ground how to read what the spacecraft says.
Operator intent, compiled into something a spacecraft can run.
How spacecraft and ground agree on what time it is.
Trusting commands across hostile infrastructure.
The unglamorous lifecycle of a key in orbit.
Authentication that survives custody transfer.
Mission software stops caring which antenna received the signal.
Cross-support service APIs that succeed the older SLE interfaces.
A common runtime for the screens that fly the spacecraft.
How agencies hand each other a spacecraft's state vector.
A standard envelope for range, Doppler, and angles.
A bus that lets one processor reach into another's memory.
SpaceWire at gigabits, with quality of service built in.
The deterministic command bus that refused to die.
Automotive heritage carrying CubeSats into orbit.
A standard shape for the wires inside the machine.