Will SpaceX carry out an in-orbit propellant transfer between two Starships before 31 March 2027?
deadline 2027-03-31
confidence low
tier 4 evidence
28%PolySignal estimate
⚠ Evidence cap applied: the model proposed 35%, brought back to 28% for lack of sources solid enough to justify the departure from the base rate.
Resolution criterion
Yes if SpaceX or NASA confirms that a ship-to-ship propellant transfer in orbit has been performed, even partially, in an official release or an HLS programme update.
Verified starting state
The propellant transfer demonstration (two launches three to four weeks apart, depot plus tanker) is planned for late 2026. Starship V3 debuted before May 2026. NASA is waiting on these milestones for Artemis III. The milestone has already slipped from 2025 to late 2026 and requires a cadence never yet sustained.
What pushes it up
- The hand‑verified tier‑1 plan schedules the transfer demo for late 2026, within the deadline [tier 1]
- Recent Starship V3 launches show hardware is reaching orbit, supporting schedule feasibility [tier 4]
What pushes it down
- No official confirmation that the transfer has been performed; only plans exist [tier 1]
- The cadence required (two launches 3‑4 weeks apart) has never been demonstrated, and the milestone has already slipped once [tier 1]
- All news articles are tier‑4 and provide no concrete evidence of a completed transfer [tier 4]
What would move this number most
An official release or NASA HLS update confirming that an in‑orbit propellant transfer has actually occurred
How this number is built
| Deadline | 2027-03-31 |
| Base rate | 20% |
| Best evidence | tier 4 · 2 article(s) used |
| Independent runs | 15 · 23 · 28 · 30 · 38 (spread 23 pts) |
| Confidence | low |
| Evidence cap | applied: 35% brought back to 28% |
| Last revised | 2026-10-02 09:14 |
| Model | openai/gpt-oss-120b (Groq) |
Sources consulted
Probability history
2026-10-02 09:14 28% 5 article(s) on file · openai/gpt-oss-120b (Groq)
- What pushes it up. The hand‑verified tier‑1 plan schedules the transfer demo for late 2026, within the deadline [tier 1]
- What pushes it up. Recent Starship V3 launches show hardware is reaching orbit, supporting schedule feasibility [tier 4]
- What pushes it down. No official confirmation that the transfer has been performed; only plans exist [tier 1]
- What pushes it down. The cadence required (two launches 3‑4 weeks apart) has never been demonstrated, and the milestone has already slipped once [tier 1]
- What pushes it down. All news articles are tier‑4 and provide no concrete evidence of a completed transfer [tier 4]
- What would move this number most. An official release or NASA HLS update confirming that an in‑orbit propellant transfer has actually occurred
2026-09-30 09:00 34% 5 article(s) on file · qwen/qwen3.8-27b (Groq)
- What pushes it up. The hand-verified starting state confirms the demonstration is explicitly planned for late 2026, which falls within the deadline [tier 1]
- What pushes it up. Starship V3 has already debuted (May 2026), removing the primary hardware dependency for the transfer test [tier 4]
- What pushes it down. The milestone requires a launch cadence (two launches 3-4 weeks apart) that SpaceX has never yet sustained, increasing the risk of further slippage [tier 1]
- What pushes it down. The milestone has already slipped once from 2025 to late 2026, indicating a history of schedule delays [tier 1]
- What pushes it down. All recent press articles are Tier 4 (pickup/aggregator) and do not provide independent confirmation of a successful test or a confirmed date beyond the general 'late 2026' window [tier 4]
- What would move this number most. Whether the 'late 2026' window extends past March 2027 or if the required launch cadence will be achieved before the deadline.
2026-09-22 00:40 13% 0 article(s) on file · openai/gpt-oss-20b (Groq)
Reasons not recorded for this revision (detailed history has only been kept since recently).