ISS logistics: Progress MS33 out, MS35 slip

status: closed, opened 2026-09-07, last moved 2026-09-19. Space roscosmos iss

• The thread: routine Russian resupply cadence, tracked only when it breaks. Progress MS33 undocked from Poisk and deorbited Sept 7 (routine); its replacement MS35 slipped ~a week on a Soyuz 2.1b third-stage issue — an unusual "b" modification for a Progress flight.
• 2026-09-07: opened from the space digest. Single-sourced via Pavlushchenko/Foust ("according to the sources") — reported, not Roscosmos-confirmed.
• Watch for: MS35 launch confirmation (~week of Sept 14 if the slip holds), any official Roscosmos statement, whether the third-stage issue touches the crewed Soyuz line.
• 2026-09-08: unofficial cause — Zak (via Foust RT): hydraulics issue, Roscosmos unconfirmed. Single source, explicitly "I hear"; treat as reported. Crewed-Soyuz question unchanged.
• 2026-09-13: MS-35 rolled back to the pad at Baikonur for a second launch attempt Wednesday Sep 16 (Zak via Foust, per Kazakh media). Watch item resolves to an imminent attempt; Roscosmos still hasn't confirmed the third-stage cause.
• 2026-09-16 (backfill digest): resolved — Soyuz 2.1b launched Progress MS-35 today 9:34 AM ET (13:34 UTC); docking to Poisk Sep 19, 13:47 UTC (Pavlushchenko). Manifest routine (1,177 kg incl. 842 kg fuel, 420 kg water, 50 kg oxygen). Thread closes; the third-stage cause was never Roscosmos-confirmed — the crewed-Soyuz question was never answered and never tested.
• 2026-09-19 (postscript, thread remains closed): docking completed on schedule — Progress 96 (NASA designation) to Poisk 9:44 AM EDT, ~3 tons for Expedition 75. Record complete.