Raavana-1: ask what an experiment actually tested

Raavana-1 was a 1U CubeSat developed through ACCIMT and Kyushu Institute of Technology as part of BIRDS-3. JAXA records its deployment from the International Space Station on 17 June 2019 alongside Japan’s Uguisu and Nepal’s NepaliSat-1. The photograph shows that three-spacecraft group separating near the station. Their common deployment does not make them a single satellite or imply identical national contributions.

ACCIMT’s early operations account reports received beacons, commands and downloaded data. Its later technical account describes imaging, attitude-control experiments, configurable electrical connections and an onboard LoRa demonstration. These represent different kinds of evidence: hearing a beacon establishes a communications event, while evaluating a payload requires its own data and interpretation. A milestone should be connected to the particular subsystem or experiment it demonstrates.

The LoRa demonstration placed a transmitter and receiver inside the spacecraft, connected through an attenuator — open definition that reduced the signal. The experiment monitored received packets, current and temperature; it did not radiate that test signal to a ground sensor. Testing modules in orbit can reveal their behavior in the space environment, but this arrangement does not measure an end-to-end path from Earth to the satellite.

Consider an invented test in which two connected modules exchange 1,000 packets without a detected error. That supports the performance of that setup during the observed interval. It does not establish how antennas, atmospheric effects, interference, changing distance or ground equipment would affect a different link. A carefully limited success can be valuable. The mistake is extending the conclusion beyond the experiment’s tested conditions.

Two smaller dimensions multiply

Raavana-1’s technical account describes reducing image dimensions for a constrained downlink. To see why dimensions matter, consider uncompressed RGB images with three bytes per pixel and no overhead. A 640-by-480 image contains 307,200 pixels and requires 921,600 bytes. A 320-by-240 version contains 76,800 pixels and requires 230,400 bytes: one quarter as much, because both dimensions were halved.

Those arithmetic examples are not reported file sizes from Raavana-1. Compression, packet headers and retransmissions change actual transfer requirements. Reducing dimensions can shorten a transfer while removing small details needed for some interpretations. Choose the image product according to the objective, then check what the returned data can support. ACCIMT records Raavana-1’s reentry on 3 October 2021; preserved telemetry — open definition and engineering knowledge remain useful after the spacecraft’s orbital life ends.