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Issue 146

04 Analysis · China · LEO

Further Analysis of Shiyan-33

27 Mar 2026: As we reported in the 6 Apr 2026 - Integrity Flash , Shiyan-33 (SY‑33) is a Chinese experimental satellite launched on 27 March 2026 aboard a Long March‑2C with a Yuanzheng‑1S upper stage from Jiuquan, successfully inserting into a sun-synchronous orbit (SSO) of approximately 485 × 505 km at 97.5° inclination.

Author Greg Gillinger Published June 1, 2026

27 Mar 2026: As we reported in the 6 Apr 2026 – Integrity Flash, Shiyan-33 (SY‑33) is a Chinese experimental satellite launched on 27 March 2026 aboard a Long March‑2C with a Yuanzheng‑1S upper stage from Jiuquan, successfully inserting into a sun-synchronous orbit (SSO) of approximately 485 × 505 km at 97.5° inclination. The use of the LM‑2C/YZ‑1S configuration—capable of delivering roughly 2,600 kg to a 500 km SSO—suggested SY‑33 may be a relatively large satellite within the Shiyan program. I asked Darren McKnight of LEOLabs for more specific details. Dr McKnight noted, “From preliminary object characterization measurements from our global radar network, it is clear SY-33 is a moderate-sized (i.e., characteristic length of 1.5 to 2.5 m) spacecraft with an above average effective spacecraft density. This leads us to assess with moderate confidence the mass is likely well less than 1,000 kg; closer to 500 to 600 kg. LeoLabs continues to persistently monitor this satellite and is providing regular updates to USG partners.” So…my hypothesis that SY-33 is a relatively large satellite looks to be incorrect. For comparison, the Russian/Iranian Khayyam imagery satellite (53370) is in this size-range (see image from Gunther’s Space Page).

Dr. McKnight’s assessment places SY‑33 at less than a quarter of the LM‑2C/YZ‑1S’s lift capacity, raising the question of why China selected such an oversized platform. I suspect China’s rationale is based on the LM‑2C’s reliability and the YZ-1S’s precision. The LM-2C has been in service for over 40 years and has had 85 successful missions in 87 flights. By comparison the Long March‑11, while carrying a clean 18-for-18 record, is a solid‑fueled vehicle limited to roughly 350 kg to a 700 km SSO—insufficient margin for SY‑33, particularly given the mass growth common in experimental programs. Commercial options such as Galactic Energy’s Ceres‑1 (~300 kg to SSO) and Landspace’s Zhuque‑2, in addition to being undersized, have both suffered recent launch failures, underscoring their relative immaturity. The YZ‑1S restartable upper stage may be the most critical element as it provides precise, multi-burn orbital insertion that solid‑fueled kick stages cannot replicate—a critical capability if SY‑33’s mission demands a tightly controlled sun‑synchronous orbit. The decision to pair a moderate‑sized experimental satellite with China’s most dependable SSO launch platform—accepting significant excess capacity in exchange for mass flexibility, orbital precision, and near‑certain mission success—strongly suggests China views SY‑33 as a high‑value asset that warrants continued monitoring.

SY-33 has settled into its desired orbit. Chinese space operators last adjusted the satellite’s SMA on ~30 Mar 2026 (three days after launch) to 496.3km. The satellite’s altitude has naturally decreased to 494.6km in the past 2 months. I don’t see any adjustments to the other orbital elements. (see Celestrak.org graph).

Russian-built/Iranian-operated Khayyam Satellite has similar mass estimate (500-600kg) as SY-33 (https://space.skyrocket.de/)

LM-2C/YZ1S Lift Off with SY-33 (nasaspaceflight.com)

SY-33 Orbit History(celestrak.org)

SY-33 Orbit Visualization(saberastro.com)

Mass to Orbit Capacity of LM-2C with YZ-1S Upper Stage(@TAbusnardo via X)