1. The archive that outlived its makers

Vernor Vinge’s A Fire Upon the Deep features archives that survive across civilizations and millennia. The desktop’s storage attachment is much more modest, but it shares the same basic job: keep data intact when no one is nearby to fix it.

Entry 222 closed the compute attachment arc. This entry looks at the attachment that lives next door.

2. Why storage is next

Compute without storage is a brain without memory. The compute attachment needs scratch space for processing, a buffer for data waiting to downlink, and a place to keep customer datasets between operations. A dedicated storage attachment separates those needs from the compute boards, so each can be scaled independently.

3. What the storage attachment does

Three jobs define the first storage attachment:

  • Compute scratch. Fast storage for intermediate files during Earth observation processing.
  • Downlink buffer. Storage for data waiting for a ground station pass or a relay window.
  • Customer archive. Long-term storage for datasets customers want kept on orbit, either for latency reasons or for jurisdictional preferences.

The relative importance of these jobs depends on the customer, so the attachment must be general.

4. Minimum viable definition

A first storage attachment could be defined as follows:

  • Form factor: one standard desktop cell slot, matching the compute attachment’s mechanical envelope.
  • Media: redundant solid-state drives built from commercial NAND, with error correction and periodic scrubbing.
  • Capacity: a few terabytes in the first generation, enough for meaningful Earth observation datasets without dominating mass.
  • Interface: standard network and power connectors, visible to the compute attachment as a distributed filesystem or block device.
  • Reliability: data replicated across multiple drives within the attachment and, ideally, across attachments.
  • Thermal: conduction-cooled through the cell wall, like the compute attachment.

5. Power estimate

Storage is generally lower power than compute per unit volume. A first storage attachment with a few terabytes of SSD capacity is likely in the 30–60 W range when active and below 10 W when idle. This is small compared to the compute attachment’s 100–150 W.

6. Robotic replacement

The same robotic replacement concept from the compute attachment applies. Storage drives live in guide rails with blind-mate connectors and retention latches. The robot swaps failed drives individually, preserving the data on replicas in other drives or attachments.

What this changes

  • Storage is the natural second attachment because compute needs memory and buffers.
  • A first storage attachment is a low-power, high-capacity cell with redundant commercial SSDs.
  • It shares mechanical and servicing conventions with the compute attachment, keeping the desktop’s attachment standard simple.
  • The next entry can explore whether storage should be a separate attachment or integrated into every compute attachment.