Getting Supplies There, and Not Throwing Things Away
SSA-02 Module 2 covered reusable launch vehicles. SSA-03 Module 7 covered the shift to agency-as-customer. Neither covered what that shift actually delivers day to day: how cargo physically reaches a station, and a genuinely new capability — keeping a satellite alive in orbit instead of simply replacing it.
Cargo Resupply
Progress
Russia — Government, Automated
The longest continuous cargo lineage flying — an uncrewed vehicle that docks fully automatically, government-operated since long before "commercial cargo" was a category at all.
Commercial Cargo
US — SpaceX Dragon, Cygnus
Flying under the COTS-descended contracts SSA-03 Module 7 covered — companies own and operate the vehicles, NASA buys the delivery as a service.
HTV / Kounotori
Japan — Now Retired
Already referenced in SSA-02 Module 5 for resupplying the ISS's life support consumables — notable for being captured and berthed by Canadarm2 rather than docking automatically like Progress.
In-Space Servicing
Most satellites don't fail because their hardware breaks — they run out of the propellant needed for station-keeping and get retired while otherwise still functional. That single fact opened an entire new mission category.
Life-Extension / Refueling
Keep It Going
A servicer spacecraft docks with an aging satellite — often one never designed to be serviced at all — and either takes over station-keeping directly or transfers fuel, extending a functioning satellite's operational life by years instead of retiring it early.
Robotic Repair & Assembly
Fix or Build in Place
A more ambitious concept: robotically repairing or reconfiguring hardware in orbit, or assembling structures too large to launch in one piece — still earlier-stage than life-extension servicing, but the same underlying shift away from "launch it once and replace it later."
Who This Changes
Historically, a fuel-depleted or damaged satellite meant total loss, followed by the full cost of a replacement launch. A real servicing industry changes that math — a satellite operator could extend a working asset's life instead of writing it off, lowering the effective lifetime cost of operating in orbit at all. Servicing itself is still early-stage and expensive today, so this is a developing shift, not a settled one — but it's the same underlying direction as the agency-as-customer move SSA-03 Module 7 covered: ownership and operation spreading out, rather than staying concentrated with whoever built the original hardware.
Key Terms
- Cargo Resupply Vehicle
- An uncrewed spacecraft delivering supplies, equipment, and consumables to a crewed station — Progress, Dragon, Cygnus, and the retired HTV are all examples.
- Station-Keeping
- The ongoing use of propellant to maintain a satellite's intended orbit — the resource most satellites actually run out of before their hardware fails.
- In-Space Servicing
- Extending, repairing, or reconfiguring a spacecraft already in orbit, rather than replacing it with a new launch.
- Life-Extension Mission
- A servicing mission that docks with an aging satellite to take over station-keeping or transfer fuel, extending its operational life.
For This Module
NASA and Roscosmos cargo resupply program materials, JAXA HTV program documentation, and public materials on commercial and government in-space servicing and life-extension missions.
Continue the Sequence
Module 8 closes SSA-05 with space-based astronomy and what's next — Hubble, JWST, and a closing survey across every destination this course has covered.