Rocket Lab’s Neutron medium-lift launch vehicle faces steep remaining hurdles that explain the 94% market-implied odds against a first flight by December 31, 2026. The company’s August 2026 earnings update shifted emphasis to Q4 pad delivery at Wallops rather than liftoff, noting that the end-of-year launch window is narrowing while prioritizing post-debut cadence and full qualification of the nine Archimedes LOX/methane engines plus Stage 1 static fire. A January 2026 tank rupture already pushed the schedule from earlier 2026 targets, and integrated vehicle testing, wet dress rehearsals, and regulatory steps still lie ahead with only weeks remaining. Traders view these factors as creating a high barrier despite ongoing hardware progress, though an anomaly-free acceleration of final tests could theoretically compress the timeline.