Mariner 10 Venus-Mercury gravity-assist tour (Mercury-I SPK-derived V_inf)

mariner-10-venus-mercury · source: literature · validation: V0

Signature

Bodies: E-V-Me-Me-Me
Primary: Sun (default — heliocentric)
Sequence (canonical): E-V-Me-Me-Me
Sense: n/a
Orbit class: Tour
MGA tour (one-shot terminal arrival)
Cycler class: multi-arc
Returns: 1 — finite for epoch-locked classes
Validity window: 1973-11-03 → 1975-03-16
Launch epoch: 1973-11-03T05:45:00Z
Trajectory regime: ballistic
Maintenance ΔV band: unclassified
Model assumption: analytic-ephemeris
Mid-fidelity: real eccentricity / inclination retained; not full N-body.
Period: not strictly periodic (no published period)
Source ephemeris: DE440 + NAIF reconstructed Mariner 10 spacecraft SPK (M10_archive_1.bsp; Mercury-I ONLY -- the public NAIF M10 archive covers only the 1974-03-21.04-04 Mercury-I window; Venus + Mercury-II/III trajectory kernels are not publicly archived in clean SPK form)
Ephemeris model the source states its numbers were computed against.
Priority date: 1973-11-03

V∞ at encounters

Me (encounter 1): 10.38 km/s
SPK-derived planetocentric V_inf at Mercury-I closest approach 1974-03-29T20:46 UTC (M10_archive_1.bsp, NAIF -76); vis-viva outer-window std 0.037 km/s; CA 1.289 R_Me / 704 km alt reproduces the published 704 km (NASA Mariner-10 mission page; Giberson-Cunningham 1975) to <0.1%. Venus (1974-02-05) and Mercury-II (1974-09-21) / Mercury-III (1975-03-16) flyby V_inf are NOT extractable: the public NAIF M10 archive contains only the Mercury-I segment.

Cycle-level identity (multi-arc invariants)

Aphelion ratio (AR): —
Turn ratio (TR): —
Transit times (days): —

Orbit view 2.5D ecliptic projection

spacecraft: analytic-ephemeris (real e/i retained) planets: J2000 osculating ellipse (Standish & Williams Table 1) orientation: coplanar-idealized (no Ω/ω published — in-plane ellipse)

3D view not available for multi-arc trajectories yet. The 3D system can now render a numerically-sampled polyline (n-body or multi-arc), but no sampled trajectory is published for this row — each leg is a separate ellipse with honest gaps where elements are unpublished (the 2D view above shows them). The button will appear here once a sampled path is exported for this trajectory; we never interpolate one from the catalogue's per-leg (a, e).

— — planet orbit (true J2000 ellipse)

Flyby altitudes (minimal-thrust)

Per-flyby periapsis altitude that delivers each encounter's required turn ballistically, capped at the body's safe flyby floor (200 km for Earth/Mars). A flyby sitting at the floor is bend-binding (it needs the deepest safe pass); higher altitudes are gentler flybys that need less turn. · source: derived

Node	Body	Altitude (km)
0	V	5,794
1	Me	713

Definition status

incomplete — core fields missing or known-unknowns tracked below

Primary citation

Giberson, W. E. & Cunningham, N. W. (1975). Mariner 10 mission to Venus and Mercury. Acta Astronautica 2(7-8):715-743.

DOI: 10.1016/0094-5765(75)90012-0

orbit source derived orbit fidelity real-de440 V∞ source derived V∞ fidelity real-de440

Corroborating sources

Acton, C. H. (1996). Ancillary data services of NASA's Navigation and Ancillary Information Facility (NAIF SPICE). Planetary and Space Science 44(1):65-70. DOI: 10.1016/0032-0633(95)00107-7
Provenance of the reconstructed Mariner 10 spacecraft SPK kernel (M10_archive_1.bsp) from the NAIF public archive that the vinf_at_flyby reads; the Mercury-I V_inf is DERIVED from this authoritative mission kernel.

Notes

Mariner 10's flown Venus-Mercury gravity-assist tour -- the FIRST dual-planet gravity-assist mission (Venus flyby retargeting to Mercury) and the FIRST to make repeated encounters with one planet (the 2:1 Mercury-resonant returns: Mercury-I 1974-03-29, Mercury-II 1974-09-21, Mercury-III 1975-03-16). The Mercury-I per-encounter V_inf is not published in clean form (Giberson- Cunningham 1975, digest, gives dates + flyby altitudes + TCM dV but no V_inf), so we derive it from the mission's archived NAIF reconstructed spacecraft SPK at the sourced flyby epoch. SPK-availability limitation (sourced negative): the public NAIF M10 archive contains ONLY M10_archive_1.bsp, which covers the 1974-03-21.04-04 Mercury-I window. The Venus gravity assist (1974-02-05) and the Mercury-II / Mercury-III re-encounters are NOT in the public NAIF archive, and the PDART SPICE-reconstruction effort that re-derived Mariner-6/7 trajectories has not (as of this writing) been extended to Mariner 10. So only Mercury-I yields a derived V_inf; the row records the full body sequence but assigns V_inf only where the SPK supports it (sourced-only discipline). Mercury-I 1974-03-29T20:46 UTC: V_inf 10.376 km/s, CA 1.289 R_Me / 704 km alt (published 704 km, NASA Mariner-10 mission page). The single SPK-derived encounter; the others remain V_inf-blocked on kernel availability. validation_level=V0 (orbit_source = vinf_source = derived -> 'unvalidated' provenance tier; V0 on validation_level), even though the Mercury-I CA altitude reproduces the published record to <0.1%. The 8th SPK-derived mga_tour row. See docs/notes/2026-06-19-390-spk-vinf-extractor.md.

Source quotes (per-field provenance)

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

launch_epoch: Mariner 10 launched 1973-11-03 (NASA Mariner-10 mission page; Giberson-Cunningham 1975 Acta Astronautica 2(7-8):715-743).
validity_window.end: Mercury-III encounter 1975-03-16, the mission's last planetary encounter (NASA; Giberson-Cunningham 1975).
vinf_kms_at_encounters.0.vinf_kms: DERIVED: planetocentric V_inf 10.376 km/s from NAIF SPK M10_archive_1.bsp (Mariner 10, body -76) at Mercury-I closest approach 1974-03-29T20:46 UTC; CA 1.289 R_Me / 704 km alt reproduces the published 704 km (NASA '45 Years Ago: Mariner 10 flies by Venus'; Giberson-Cunningham 1975) to <0.1%.
n_returns: Single Earth launch (1973-11-03); n_returns=1. Mariner 10's repeated-Mercury encounters are a 2:1 resonance about the Sun, not Earth returns; per the v4.7 mga_tour invariant (no continuing tour at Earth).