Resumen: A purely algebraic formulation (i.e., polynomial equations only) of the minimum-cost multi-impulse orbit-transfer problem without time constraints is presented, while keeping all the variables with a precise physical meaning. General algebraic techniques are applied to solve these equations (resultants, Gröbner bases, etc.) in several situations of practical interest of different degrees of generality. For instance, a proof of the optimality of the Hohmann transfer for the minimum-fuel two-impulse circular-to-circular orbit-transfer problem is provided. Finally, a general formula is also provided for the optimal two-impulse in-plane transfer between two rotated elliptical orbits under a mild symmetry assumption on the two points where the impulses are applied (which, it is conjectured, can be removed). Idioma: Inglés DOI: 10.2514/1.G001598 Año: 2016 Publicado en: JOURNAL OF GUIDANCE CONTROL AND DYNAMICS 39, 8 (2016), 1734-1743 ISSN: 0731-5090 Factor impacto JCR: 1.856 (2016) Categ. JCR: ENGINEERING, AEROSPACE rank: 5 / 31 = 0.161 (2016) - Q1 - T1 Categ. JCR: INSTRUMENTS & INSTRUMENTATION rank: 22 / 58 = 0.379 (2016) - Q2 - T2 Factor impacto SCIMAGO: 1.181 - Aerospace Engineering (Q1) - Applied Mathematics (Q1) - Control and Systems Engineering (Q1) - Electrical and Electronic Engineering (Q1) - Space and Planetary Science (Q2)