Pioneer 11 Jupiter-Saturn gravity-assist tour (first Saturn encounter), SPK-derived V_inf

pioneer-11-jupiter-saturn-flyby · source: literature · validation: V0

Signature

Bodies: E-J-S
Primary: Sun (default — heliocentric)
Sequence (canonical): E-J-S
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: 1973-04-06 → 1979-09-01
Launch epoch: 1973-04-06T02:11:00Z
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 Pioneer 11 spacecraft SPKs (p11-a.bsp Jupiter; p11_sat336.bsp Saturn-relative)
Ephemeris model the source states its numbers were computed against.
Priority date: 1973-04-06

V∞ at encounters

J (encounter 1): 8.93 km/s
SPK-derived planetocentric V_inf at Jupiter closest approach 1974-12-03T05:22 UTC (p11-a.bsp, NAIF -24); vis-viva outer-window std 0.0004 km/s; CA 1.590 R_J / 42,174 km alt reproduces the published 42,500 km (NASA Science Pioneer-11 page) to ~1%.
S (encounter 2): 8.36 km/s
SPK-derived planetocentric V_inf at Saturn closest approach 1979-09-01T16:31 UTC (p11_sat336.bsp, NAIF -24); vis-viva outer-window std 0.003 km/s; CA 1.344 R_S / 20,713 km alt reproduces the published 20,900 km (NASA Science Pioneer-11 page) to ~1%.

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no sampled trajectory is published for this row — each leg is a separate ellipse with honest gaps where elements are unpublished (the 2D view above shows them).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)

Definition status

incomplete — core fields missing or known-unknowns tracked below

Primary citation

NASA Science (2024). Pioneer 11 (mission overview / encounter parameters). NASA Science mission pages (science.nasa.gov/mission/pioneer-11).

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 Pioneer 11 spacecraft SPK kernels (p11-a.bsp, p11_sat336.bsp) from the NAIF public archive that the vinf_at_flyby reads; the V_inf is DERIVED from these authoritative mission kernels.

Notes

Pioneer 11's flown Jupiter-Saturn gravity-assist tour -- the first spacecraft to encounter Saturn (1979-09-01), reached via a Jupiter gravity assist (1974-12-03) that cranked the trajectory up and across the solar system to Saturn. Structurally the Voyager-1 archetype (E-J-S two-giant-planet tour), flown two years earlier as the Saturn pathfinder. As with the Voyager rows, the per-encounter V_inf is not in the acquired literature in clean form, so we derive it from the mission's archived NAIF reconstructed spacecraft SPK at the sourced flyby epochs (cyclerfinder.verify.mission_spk.vinf_at_flyby). Encounters: * Jupiter 1974-12-03T05:22 UTC: V_inf 8.934 km/s, CA 1.590 R_J / 42,174 km alt. Reproduces the published 42,500 km (26,400 mi from cloud tops; NASA Science Pioneer-11 page) to ~1%. * Saturn 1979-09-01T16:31 UTC: V_inf 8.359 km/s, CA 1.344 R_S / 20,713 km alt. Reproduces the published 20,900 km (13,000 mi; NASA Science Pioneer-11 page) to ~1%. Saturn-relative kernel p11_sat336.bsp covers only 1979-08-20.09-04, so the extraction window is bracketed inside it. Earth departure (1973-04-06) carries no V_inf entry (sourced-only discipline, as for Pioneer 10 / the Voyager rows): the launch is documented but not assigned a fabricated departure V_inf. validation_level=V0 for the same orthogonal-axis reason as the Voyager / Pioneer-10 rows (orbit_source = vinf_source = derived -> 'unvalidated' on the provenance-tier axis; V0 on validation_level even though CA geometry matches the published record to ~1%). The fifth 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: Pioneer 11 launched 1973-04-06 02:11 UTC (NASA Science 'Pioneer 11' mission page; consistent with p11-a.bsp SPK coverage start 1973-04-06 02:25).
validity_window.start: Same as launch_epoch (Pioneer 11 launch 1973-04-06).
validity_window.end: Saturn closest approach 1979-09-01T16:31 UTC, the last SPK-derived encounter (NASA Science Pioneer-11 page; p11_sat336.bsp periapsis refinement).
vinf_kms_at_encounters.0.vinf_kms: DERIVED: planetocentric V_inf 8.934 km/s from NAIF SPK p11-a.bsp (Pioneer 11, body -24) at Jupiter closest approach 1974-12-03T05:22 UTC (outer-window std 0.0004 km/s). CA 1.590 R_J / 42,174 km alt reproduces the published 42,500 km (NASA Science Pioneer-11 mission page) to ~1%.
vinf_kms_at_encounters.1.vinf_kms: DERIVED: planetocentric V_inf 8.359 km/s from NAIF SPK p11_sat336.bsp (Pioneer 11, body -24) at Saturn closest approach 1979-09-01T16:31 UTC (outer-window std 0.003 km/s). CA 1.344 R_S / 20,713 km alt reproduces the published 20,900 km (NASA Science Pioneer-11 mission page) to ~1%.
n_returns: Single Earth launch (1973-04-06) and single Saturn arrival (1979-09-01); n_returns=1 per the v4.7 mga_tour invariant (no continuing tour at Earth).