Is this flight software?

No. SIDUS models are educational reimplementations. Cross-check before any flight decision.

GEO drift rate

Longitude drift from a vs a_GEO.

SIDUS educational calculator. Category orbital. Tags: geo, operations, orbital. Pure SI. Not flight software.

λ̇ ∝ −(a − a_GEO)/a_GEO

GEO longitude drift rate

Fundamentals of Astrodynamics and Applications (David A. Vallado): Standard reference for two-body, Lambert, maneuvers, and J2. Equations implemented independently in SIDUS.
Orbital Mechanics for Engineering Students (Howard D. Curtis): Textbook derivations for Hohmann, vis-viva, rocket equation, elements.

Read /llms.txt or call https://sidus.tools/api/mcp. Open the interactive page for live SI inputs.