NASA's Advanced Communications Technology Satellite ceased experimental operations at midnight on May 31, 2000. An experiment on the performance of a "paced" TCP was taking place up until the time the satellite was "turned off". The experiment was being conducted by NASA GRC and BBN Technologies. The experiments were conducted between the Pittsburgh Supercomputer Center and NASA GRC. The following is the tcptrace rendering of the last IP packet sent over ACTS:
Packet 4631 Packet Length: 66 Collected: Wed May 31 23:58:52.643950 2000 ETH Srce: 00:a0:c9:dc:15:e3 ETH Dest: 00:00:0c:4d:f0:a0 Type: 0x800 (IP) IP VERS: 4 IP Srce: 126.96.36.199 (uhoh.psc.edu) IP Dest: 188.8.131.52 (gmc.lerc.nasa.gov) Type: 0x6 (TCP) HLEN: 20 TTL: 64 LEN: 52 ID: 39542 CKSUM: 0xde7d OFFSET: 0x4000 Don't Fragment TCP SPRT: 2070 DPRT: 3192 FLG: -A---- (0x10) SEQ: 0xe22d4335 ACK: 0x1396be26 WIN: 62500 HLEN: 32 CKSUM: 0x03c5 DLEN: 0 OPTS: 12 bytes TS(1414930100,3882512)
Fittingly, this packet is the acknowledgment that finishes this particular TCP connection. The full packet-level dumps from the connection are available in tcpdump format:
Also among the last users of ACTS were a team of researchers from Ohio University and NASA GRC, who were exploring the performance of a large number of simultaneous TCP transfers over ACTS.
Finally, we understand that the last phone call over ACTS was in progress at midnight when the satellite was "turned off".