Astro

astro encodes, decodes, inspects, and validates CCSDS data from a terminal. It reads stdin and writes stdout, so commands pipe into each other and into jq.

If you have not used it yet, start with the CLI quickstart.

Commands

Command	Protocol
`astro spp`	Space Packets	encode, decode, inspect, validate, stream, gen
`astro epp`	Encapsulation Packets	encode, decode, inspect, validate, stream, gen
`astro tm`	TM transfer frames	encode, decode, inspect, gaps, demux, gen
`astro tc`	TC transfer frames	encode, decode, inspect, gen
`astro aos`	AOS transfer frames	encode, decode, inspect, gaps, demux, gen
`astro usdl`	USLP transfer frames	encode, decode, inspect, gen
`astro cadu`	Channel Access Data Units	wrap, unwrap, inspect, sync, gen
`astro cltu`	Command Link Transmission Units	wrap, unwrap, inspect, gen
`astro time`	Time codes	encode, decode, inspect, now
`astro xtce`	XTCE mission databases	validate, list, layout, decode, match
`astro pus`	PUS services	encode, decode, services
`astro ldc`	Lossless data compression	compress, decompress, inspect
`astro rhc`	Robust housekeeping compression	compress, decompress
`astro cfdp`	CCSDS File Delivery Protocol	decode
`astro ltp`	Licklider Transmission Protocol	decode
`astro bp`	Bundle Protocol v6	decode, admin
`astro sle`	Space Link Extension	decode
`astro cop`	COP-1 control words	clcw-encode, clcw-decode
`astro pxdl`	Proximity-1 data link	encode, decode, spdu
`astro pxsc`	Proximity-1 coding	wrap, unwrap, sync, encode, decode
`astro ocsc`	Optical coding	condition, randomize
`astro sdls`	Space Data Link Security	inspect

Shared flags

Every command that reads input takes:

Flag	Default	Meaning
`--input`	`hex`	`hex` for hex-encoded text, `bin` for raw binary

Every command that writes output takes:

Flag	Default	Meaning
`--format`	varies	`text`, `json`, or `hex`

Input comes from a file argument or from stdin. Hex input tolerates a 0x prefix, spaces, and newlines, so you can paste from a log without cleaning it up.

The verbs

They mean the same thing everywhere.

encode builds a unit from flags. decode takes one apart into fields. inspect does the same but prints an annotated hex dump alongside. This is the one for staring at a capture. validate checks a unit is well formed and reports what is wrong. stream reads a concatenated run of units from a file or pipe. gen produces synthetic test data. wrap and unwrap add and remove a coding layer.

Piping

Layers compose the way the protocol stack does:

# Packet -> frame -> CADU
PKT=$(astro spp encode --apid 100 --type tm --data 68656c6c6f)
FRAME=$(astro tm encode --scid 42 --vcid 0 --data "$PKT")
echo "$FRAME" | astro cadu wrap --input hex

# Encode, then look at what you built
astro spp encode --apid 100 --type tm --data 68656c6c6f \
  | astro spp inspect --input hex

# Anything decodable can go to jq
astro spp gen --apid 100 --count 100 --format hex \
  | astro spp stream --input hex --format json \
  | jq 'select(.apid == 100) | .sequence_count'

Binary files

Use --format bin on the way out and --input bin on the way in:

astro spp gen --apid 100 --count 1000 --format bin > capture.bin
astro spp stream --input bin capture.bin

CRC handling

Where a protocol makes error control optional, both ends must agree. Pass --crc when encoding and when decoding:

astro spp encode --apid 100 --type tm --data a1b2c3d4 --crc \
  | astro spp validate --input hex --crc

Leave it off the decode side and the CRC bytes come back as payload. That mismatch is the most common first bug.

Built-in manual

Every command's full reference is embedded in the binary:

astro manual        # list the topics
astro manual spp    # the full spp reference

These are the same pages as this section of the site.