Solar Cycle 25 & The 5-Year Deorbit Rule: Why 500–550 km SSO PocketQubes Pass Without Propulsion Under Moderate-to-Active Solar Conditions
Because a 250 g 1P PocketQube (B ≈ 0.033–0.039 m²/kg) has roughly double the ballistic parameter of a 1.33 kg 1U CubeSat, natural atmospheric drag clears 1P missions from 525–550 km within 2.3–4.3 years under moderate solar flux (F10.7 = 140 sfu), whereas prolonged solar minimum (F10.7 = 70 sfu) lowers the 5-year ceiling to ~493–500 km.
Under the FCC 5-year post-mission disposal rule (IB Docket 18-313, effective September 2024) and ESA Space Debris Mitigation Requirements (ESSB-ST-U-007 Issue 1, 2023) alongside the Zero Debris Charter, low-Earth-orbit spacecraft must complete atmospheric re-entry within five years of mission completion.
For a 1.33 kg 1U CubeSat (ballistic parameter B = C_D·A/m ≈ 0.0165 m²/kg face-on to 0.0248 m²/kg tumbling), rideshare deployments above ~521–543 km under moderate solar activity (F10.7 = 140 sfu, Ap = 12)—or above ~463–481 km under solar minimum (F10.7 = 70 sfu, Ap = 6)—exceed the 5-year threshold without drag augmentation or propulsion.
By contrast, a 250 g 1P PocketQube (B ≈ 0.0330 m²/kg bare tumbling to 0.0387 m²/kg with deployed UHF dipole) decays from 550 km in ≈3.6–4.3 years (and from 525 km in ≈2.3–2.7 years) under moderate solar activity, remaining below the 5-year ceiling up to ~559–568 km (note: Kennewell/IPS 1999 polynomial density is extrapolated above its 500 km calibration limit; under deep solar minimum F10.7 = 70 sfu, the 5-year ceiling drops to ~493–500 km). These moderate-to-active Cycle 25 lifetimes are consistent with CelesTrak SATCAT re-entry epochs for 525 km Transporter-3 PocketQubes (Grizu-263A: 1.72 yr, Delfi-PQ: 1.98 yr).
Published Proceedings, Open-Access Papers & Primary Dossiers
CELESTRAK SATCAT & TELEMETRY RECORD
Verified Spacecraft Key Facts & Orbital Dossier
| Spacecraft | Class | Operator / Country | Launch & Vehicle | NORAD / COSPAR | Orbit & RF Downlink | Catalog Status |
|---|---|---|---|---|---|---|
Grizu-263A | 1P | Zonguldak Bülent Ecevit Univ. TR | Falcon 9 (Transporter-3) · AlbaPod | NORAD 51025 2022-002AT | ≈525 km Sun-synchronous, 97.4° 437.19 MHz, 435.675 MHz (UHF) | Decayed |
Delfi-PQ | 3P | TU Delft NL | Falcon 9 (Transporter-3) · AlbaPod | NORAD 51074 2022-002CU | 436.65 MHz (UHF) | Decayed |
Catalogued Mission Summaries & Flight Notes
- Grizu-263A (1P, 2022):
- Türkiye’s first PocketQube, built by the Grizu-263 Space Team: passive magnetic attitude control, a dual-rate UHF FSK downlink and a digipeater. Re-entered on 2 Oct 2023 (CelesTrak SATCAT) / 3 Oct 2023 00:00 UTC (SatNOGS DB) after 627–628 days (about 9,500 revolutions); the pre-launch expectation was about four years in orbit.
- Delfi-PQ (3P, 2022):
- TU Delft’s first PocketQube: PQ9 bus, three magnetorquers and two IMUs, about 1 W orbit-average power; operated for almost two years.