BHUTAN-1: hear a satellite, then test its relay

Bhutan-1, styled BHUTAN-1 by its project team, was Bhutan’s contribution to BIRDS-2 at Kyushu Institute of Technology. It traveled to the International Space Station in June 2018 and was released from Kibo on 10 August alongside Maya-1 from the Philippines and UiTMSAT-1 from Malaysia. The shared project supplied a setting in which engineers could learn a complete small-satellite development process.

The deployment photograph shows the three spacecraft together. It supports the event history without assigning an unverified national identity to each visible position. Bhutan’s 2020–2021 departmental report later described the end of BHUTAN-1’s orbital mission. Its proposed reentry timing is a historical estimate, not evidence of a precisely observed impact location. An educational mission can finish while the team continues to use its engineering experience.

The BIRDS-2 operations plan anticipated a practical problem: three similar spacecraft released together would send housekeeping beacons on the same frequency. If they transmitted together, a ground receiver could have difficulty decoding them. The initial plan staggered their starts and used a thirty-second transmission followed by eighty-five seconds of silence for each spacecraft.

For that planned 115-second cycle, a single beacon transmits about twenty-six percent of the time: thirty divided by 115. The quiet interval is useful coordination, not proof that the spacecraft has stopped working. Real receptions also depend on geometry, signal strength and timing drift. An operator needs the spacecraft’s identification and a decodable message, not just evidence that some radio energy reached the antenna.

Separate channel time from mission health

Housekeeping telemetry reports information about the spacecraft itself. An APRS digipeater — open definition instead receives an addressed packet and retransmits it so another station may receive it. The team’s 23 August 2018 update reported that the APRS transceiver had been activated and its beacon received, while inviting users to report their packet-relay results. Hearing its own beacon does not by itself demonstrate that an uploaded packet was accepted and repeated.

For a controlled test, give each transmitted packet a unique sequence number and record time, sender and receiver. If eight of ten unique packets return, the measured end-to-end fraction for that test is eighty percent. Repeated copies of one packet should not be counted as additional successful inputs. To locate a failure, distinguish the uplink, onboard handling and downlink; strong reception on the last leg does not establish that the first leg worked. These invented packet counts illustrate how to assess the relay.