Glossary

Product names

Parsimoni Platform

Parsimoni Platform is the product that includes Space CLI, Space Store, Space CCSDS, and SpaceOS. The overview defines the role of each component.

Space CLI

Space CLI is the space command-line client. The CLI reference lists its commands.

Space Store

Space Store is the Platform application catalog. run.space is the hosted service.

Space CCSDS

Space CCSDS is the Platform’s OCaml implementation of CCSDS protocols.

SpaceOS

SpaceOS is the on-board runtime for payload workloads. The architecture manual defines its boundary.

Platform terms, for space engineers

Composition

A composition is a signed system release. It records partitions and services. It also records shared storage and service interfaces.

Partition

A partition is the unit of isolation and supervision for a workload. It can contain a unikernel or a Linux container.

Supervision page

A supervision page is shared memory between the host and a partition. It carries liveness state and mission time. It also carries health state and the safe-mode command word.

Blue/green rollout

A blue/green rollout starts a new workload generation beside the active generation. A health check controls the switch.

Content store and root flip

The content store holds bootable images by digest. A root flip changes the pointer that selects the next image.

OCI image

An OCI image is a manifest and a set of content-addressed layers in the Open Container Initiative image format. SpaceOS uses this format to package Linux applications and unikernels. The architecture manual explains this packaging model.

Registry

A registry stores and serves OCI images by name or digest.

Container

A Linux container isolates processes with kernel namespaces and resource limits. It shares the host kernel. runc is one container runtime. This definition does not state that the installed Space release provides a runc backend.

Unikernel

A unikernel links one application with the operating-system libraries it needs. The result is a single-purpose machine image. The architecture manual explains library operating systems.

Solo5 and tenders

Solo5 defines a host interface for unikernels. A tender is the host executable that creates a sandbox and loads the unikernel. This definition does not state which tenders the installed Space release provides.

dom0

dom0 is the control domain in a conventional Xen system. It runs the management toolstack and can provide device backends. A dom0less Xen system starts guests without a control domain. The installed Space release does not publish a Xen target contract.

Content-addressed

Content-addressed data is named by a cryptographic digest of its bytes. The same bytes produce the same digest. A mutable tag such as :latest is not a content address.

IOMMU

An input-output memory management unit (IOMMU) restricts the physical memory that a device may access.

TPM

A Trusted Platform Module (TPM) stores cryptographic keys and monotonic counters outside the main processor.

dm-verity

dm-verity is the Linux block-integrity mechanism. It verifies filesystem blocks against a hash tree whose root is trusted by the boot configuration.

TUF

The Update Framework (TUF) is a model for signed update metadata. It uses a pinned root key, delegated roles, signature thresholds, and version checks.

CBOR

Concise Binary Object Representation (CBOR) is the binary data format defined by RFC 8949. It supports maps, arrays, strings, numbers, and byte strings.

COSE

CBOR Object Signing and Encryption (COSE) defines security envelopes for CBOR data. RFC 9052 defines the message structures.

Capability envelope

A capability envelope is the signed list of resources a partition may access.

Measured launch

A measured launch records the software selected for a boot before it starts.

SBOM

A software bill of materials (SBOM) is a machine-readable inventory of software components. SPDX and CycloneDX are common SBOM formats. See the Platform SBOM overview.

Context

A context is a named set of service endpoints used by Space CLI.

Healthcheck

A healthcheck is a probe that reports whether an application can serve work.

Spacecraft terms, for software engineers

CCSDS

The Consultative Committee for Space Data Systems (CCSDS) publishes standards for spacecraft communications and data handling.

Telemetry and telecommand (TM/TC)

Telemetry (TM) carries measurements and state from a spacecraft. Telecommand (TC) carries instructions to a spacecraft.

APID

An Application Process Identifier (APID) is an 11-bit CCSDS packet label. It identifies the application data stream carried by a packet.

Frame bus

The frame bus is the on-board path for CCSDS packets between partitions and the flight domain. It also connects to the ground link.

SCID / VCID

The Spacecraft Identifier (SCID) selects a spacecraft at the CCSDS link layer. The Virtual Channel Identifier (VCID) selects a logical channel within that spacecraft link.

SDLS

Space Data Link Security (SDLS), CCSDS 355.0-B, authenticates data-link frames. It can also encrypt them. SDLS protection terminates at each link hop.

OTAR and ML-KEM

Over-the-air rekeying (OTAR) replaces a link session key through the link. ML-KEM is the post-quantum key-encapsulation algorithm defined by NIST FIPS 203.

DTN

Delay- and disruption-tolerant networking (DTN) assumes that an end-to-end path may be unavailable. Nodes store data until a forwarding link is available.

BPv7 / BPSec

Bundle Protocol version 7 (BPv7) is the DTN protocol defined by RFC 9171. Bundle Protocol Security (BPSec) adds the security blocks defined by RFC 9172.

Endpoint ID and convergence layer

An endpoint ID names a BPv7 node or service. For example, ipn:7.1 names service 1 on node 7. A convergence layer carries bundles over a transport. Its convergence-layer adapter address identifies the transport endpoint.

CFDP

The CCSDS File Delivery Protocol (CFDP), CCSDS 727.0-B, transfers files over space links. It supports checkpoints and selective retransmission. A transfer can resume in a later contact window.

Contact window

A contact window is the period when a spacecraft can communicate with a specific ground station.

Downlink

Downlink is the spacecraft-to-ground direction of a communications link. The term also describes the act of sending data in that direction.

Acquisition

An acquisition is one observation recorded by an instrument. An Earth observation acquisition includes its capture time and ground footprint. It also records the map projection used for its pixels.

TLE

A two-line element set (TLE) describes an orbit at a stated epoch. Orbit propagation combines it with a ground station location to calculate contact times.

OBC

An on-board computer (OBC) is a computer installed on a spacecraft.

BSP

A board support package (BSP) contains the software needed to boot an operating system on one board. It normally includes the bootloader and kernel. It also includes the device tree and drivers.

RTOS

A real-time operating system (RTOS) provides bounded timing guarantees for specified operations.

Separation kernel

A separation kernel isolates partitions in memory and time. It can keep flight and payload trust domains separate on one physical computer.

Flight software / bus software

Flight software is the safety-critical software that controls the spacecraft. Bus software is the flight software that manages the spacecraft platform and its shared devices.

FDIR

Fault detection, isolation, and recovery (FDIR) covers fault detection, containment, and service recovery.

SEU

A single-event upset (SEU) is a state change caused by ionizing radiation. A bit flip in memory is a common example.

Ground segment

The ground segment contains the systems on Earth that operate a spacecraft and process its data. It includes ground stations and mission operations systems.