First to produce an antimatter-catalysed fusion reaction
The finish line
A controlled laboratory fusion reaction shows a statistically significant ignition-rate increase caused by introduced antimatter or positrons and is independently reproduced.
Why it is still open
NASA classifies positron-catalysed fusion as a TRL 1–2 concept; no experimental thrust demonstration has been realised.
NASA · Radioisotope Positron Propulsion ↗