“Not simply radio. Not simply networking.” This course is about moving mission information through a complete system.
The Communications Problem
- At its simplest: a sender pushes a message toward a receiver, and the receiver has to pick it out of everything else it hears (the slide sketch: a figure with a megaphone, an arrow, and a listener surrounded by noise rings)
- Spacecraft communications moves commands, telemetry, science, navigation measurements, and other information across imperfect connections
- The users span a huge range of situations, e.g.:
- An Earth-orbiting spacecraft
- A person on the ground with a handheld device
- A deep-space spacecraft at an asteroid
- Astronauts and rovers on the lunar surface
Two Perspectives, One Complete System
- Mission view: what information must arrive — and when?
- Provider view: what services can shared assets deliver?
- Those meet in radio links + networks and operations
- Result: mission information reaches its user
- The same split shows up inside a single link as the spacecraft team vs. network provider viewpoints
A Working Vocabulary
- Link: one transmitter-to-receiver connection
- Service: a capability delivered to a user
- Provider: shared assets and operations serving multiple missions
- Network: connected assets and rules that move data end to end
- Architecture: the chosen arrangement of functions, interfaces, and resources
Constraints Are Part of the Design
- Size, weight, and power
- Spectrum and interference
- Cost, schedule, complexity, and risk
- Shared provider capacity and scheduling
Everything Is a Trade
- “Everything is a trade. The equations help us make the trade honestly.”
- Syllabus version: equations support engineering judgment; they do not replace it
Spectrum and Security Shape Design
- Spectrum: allocation, bandwidth, and interference
- Commands: authorization and integrity
- Telemetry and science: confidentiality needs may differ
- Networks: every provider interface creates a trust boundary
- Resilience and security are related — but they are not the same thing
A Design Must Work End to End
- Link budget — can a representative link work? (see Link Budget)
- Coverage — is the service available when needed? (see Antenna Coverage)
- Data delivery — can information arrive in time? (see Data Volume, Rate, and Latency)
- Mission use — does the result support operations?
- Assumptions — what could change the answer?
WARNING
- A link that closes is necessary, but it is not sufficient if coverage, data flow, latency, operations, or interoperability fail
Six Questions Test the Complete System
- Does the link close?
- Is service available when needed?
- Can the network carry the offered load?
- Does the data reach the final user on time?
- Can the provider serve this mission along with the others?
- Can we defend the complete architecture?
Before you leave (Class 1 exit question)
- Name one mission communications need for a mission you know — and one fact still missing before you could design the system