[3] Terran 1's first and only launch took place March 23, 2023 from Cape Canaveral, but did not achieve orbit due to a failure of the second stage.

The first stage is powered by nine Aeon 1 engines burning methane and oxygen propellants (methalox) in a gas-generator cycle, each producing 100 kN (23,000 lbf) of thrust.

The second stage is powered by a single vacuum-optimized version of Aeon 1,[5] known as AeonVac, producing 126 kN (28,300 lbf) of thrust in vacuum.

[8][6][9] In any case, the vehicle never carried payloads, its sole launch featured an inert nosecone in place of a functional clamshell fairing.

[8] 90% of Terran 1 by mass consisted of printed components;[8] Relativity claimed that they could reduce the part count in the vehicle by 100 times compared to traditionally-manufactured rockets and manufacture an entire flight article from raw materials in 60 days.

[7] Terran 1's initial flight scheduled for 8 March 2023 was scrubbed due to "exceeding launch commit criteria limits for propellant thermal conditions on stage two".

After holding twice from a boat in the launch safety range, and high upper-level winds, the rocket lifted off at 03:25 UTC (23:25 EDT).

Preliminary investigations blamed the failure on a slower-than-expected valve opening as well as vapor ingestion into the liquid oxygen turbopump causing reduced performance.