Niehoff VISIT-2 Earth-Mars cycler

niehoff-visit2 · source: literature · validation: V0

Signature

Bodies: E-M
Primary: Sun (default — heliocentric)
Sequence (canonical): E-M
Sense: n/a
Orbit class: Cycler
strict cycler (infinite returns)
Cycler class: single-ellipse
Trajectory regime: ballistic
Maintenance ΔV band: unclassified
Model assumption: circular-coplanar
Idealised: planets on circles, coplanar ecliptic.
Period: 14.950 yr (7 × E-M synodic)
REVIEW FIX (2026-05-31): similar arithmetic-check to VISIT-1. The a = 1.31 AU element gives heliocentric orbital period P = 1.31^1.5 ≈ 1.50 yr → 2 orbits in 3 yr (matches Earth encounters) and 5 orbits in 7.5 yr (4 Mars years = 4 × 1.88 = 7.52, matches Mars encounters). The "7 synodic periods" / 14.95 yr framing from Rogers 2012 footnote 'a' is consistent with these elements; the apparent inconsistency in earlier-noted secondary sources resolves cleanly once the orbital period is computed from (a, e).
Fleet size: 14 vehicles
Priority date: 1985-07-01

V∞ at encounters

E (encounter 1): — (not published)
Same gap as VISIT-1 — V_inf for the cycler itself not directly tabulated in accessible sources.
M (encounter 2): — (not published)
Same gap.

Orbit elements (heliocentric)

Semi-major axis a: 1.310 AU
Eccentricity e: 0.275
Perihelion: 0.950 AU
Aphelion: 1.670 AU
Inclination: 0.00°

Rogers et al. 2012 Table 1. NB aphelion 1.67 AU is ~Mars's aphelion in the real ephemeris; this VISIT-2 orbit only intersects Mars's orbit when Mars is near aphelion.

Orbit view 2.5D ecliptic projection

spacecraft: idealized coplanar ellipse planets: J2000 osculating ellipse (Standish & Williams Table 1) clock: idealized phase clock (no epoch) orientation: coplanar-idealized (no Ω/ω published — in-plane ellipse) encounters: time-true on the idealized phase clock (real mean motions, phase chosen so the geometry's encounters occur)

Encounter proximity — spacecraft↔planet distance over one period; the dips are the encounters

Earth min 162279 km

Mars min 0.046 AU

Edge-on (X–Z) — i = 0° (coplanar-idealized — flat in this view)

— — planet orbit (true J2000 ellipse) ——— cycler ellipse ○ △ □ encounters (E, M)

Definition status

incomplete — core fields missing or known-unknowns tracked below

Primary citation

Niehoff, J. (1985). Manned Mars Mission Design. Joint AIAA/Planetary Society Conference 'Steps to Mars', National Academy of Sciences.

orbit source Rogers et al. 2012, Table 1 orbit fidelity circular-coplanar

Corroborating sources

Niehoff, J. (1986). Pathways to Mars: New Trajectory Opportunities. AAS Paper 86-172.
Friedlander, A. L. et al. (1986). Circulating Transportation Orbits Between Earth and Mars. AIAA 86-2009-CP. DOI: 10.2514/6.1986-2009
Niehoff, J. C. (1970). Touring the Galilean Satellites. AAS/AIAA Astrodynamics Conference, Santa Barbara, Aug 19-21, 1970; AIAA Paper 70-1070.
(2026-06-19): Niehoff's foundational Galilean multi-flyby tour paper (15 yr before VISIT). Same inertially-fixed-resonant-orbit paradigm transposed Jupiter (1970) -> Sun / Earth-Mars (1985 VISIT). See docs/notes/2026-06-17-digest-niehoff-1970.md.

Notes

Per spaceflighthistory.blogspot (summarising Niehoff 1985): "A VISIT-2 orbit would need 1.5 Earth years to complete, with a spacecraft encountering Earth twice in three Earth years and Mars five times in four Mars years." Rogers 2012's (a, e, peri, apo) numbers imply orbital period P = 2pi*sqrt(a^3/mu_sun) ≈ 1.50 yr, consistent. Same source-mismatch caveats as VISIT-1 apply.

Source quotes (per-field provenance)

Every numerical value in this entry traces to a verbatim or paraphrased quote from a cited source.

a_au: Rogers et al. 2012 Table 1: 'VISIT-2... Semi-Major Axis, AU: 1.31'.
e: Rogers et al. 2012 Table 1: 'VISIT-2... Eccentricity: 0.275'.
perihelion_au: Rogers et al. 2012 Table 1: 'VISIT-2... Perihelion Radius, AU: 0.95'.
aphelion_au: Rogers et al. 2012 Table 1: 'VISIT-2... Aphelion Radius, AU: 1.67'.
period.years: Rogers 2012 Table 1 footnote a: 7 synodic periods = 14.95 yr.