Juice

Trajectory record

Precise trajectory

Sun-centred J2000 states sampled offline from NASA/JPL NAIF SPICE kernels with geometric (NONE) aberration correction, using ESA/ESOC Flight Dynamics' reconstructed and predicted cruise orbit juice_orbc_000111_230414_310721_v01.bsp - the archive names that file type orbc, "S/C reconstructed and predicted cruise orbit from Flight Dynamics", and its own comment area records it as delivered by the Flight Dynamics team on 27 August 2026 - with DE440s furnished last so planetary positions match the committed body ephemerides. No satellite ephemeris is furnished because DE440s carries the Moon's own body centre, NAIF 301, directly; the Mars-shaped problem that made a companion kernel necessary for the Rosetta dataset does not arise here. Kernel precedence, which normally decides which navigation solution an encounter is measured against, cannot bite on this spec: the only spacecraft kernel declares coverage for body -28 alone and DE440s declares none for it, so no two furnished SPKs overlap - measured by computing the Moon closest-approach separation under the spec's furnish order and again with DE440s loaded before the cruise arc, which agree to 0.000000000 km. Sampling is weekly across the cruise and tightens to 60 s within six hours of each closest approach. Coverage runs from the kernel's first tracked state, about a minute after launch, to 2026-08-22T00:00:00Z. That endpoint is not the kernel's: the kernel runs to 21 July 2031 and the archive publishes no boundary inside it between the reconstructed part and the predicted part, so this record stops at the end of the committed body ephemerides in public/data/ephemerides, five days before the Flight Dynamics delivery this file came from, which is also where both Voyager datasets stop. Two encounters are committed, and both come from one list of "the finally reconstructed parameters of the swing-by" in a single ESA/ESOC paper: the Moon at 2 489.519 km and the Earth at 13 210.572 km. Each figure is centre-relative, and the paper settles that itself rather than leaving it to be inferred - it prints the surface distance in the same sentence as the closest-approach distance, and 2489.519 minus the Moon's 1737.4 km radius, read from the same pck00011.tpc this dataset furnishes, is 752.119 km, which is the paper's own 752 km. Under a surface reading the sentence would contradict itself. The computed centre distances are 2489.870 km and 13210.301 km, 0.351 km above and 0.271 km below the published values. The published epochs carry milliseconds - 21:14:54.681 UTC and 21:56:13.637 UTC - while this pipeline records whole-second UTC, so the spec stores the second each instant falls in rather than rounding into the next one, and the computed closest approaches at 21:14:54.647 and 21:56:13.587 sit 0.034 s and 0.050 s from the published instants. For both encounters the barycentre and the centre are the same point - NAIF 301 for the Moon, and NAIF 399 for Earth because the committed earth ephemeris targets Earth's centre rather than the Earth-Moon barycentre - so the barycentre offset the viewer draws against is exactly zero rather than merely small. The Moon has no committed body ephemeris, so the cross-asset check that compares one against the recorded body position does not run for that encounter and the Earth encounter is what exercises it; the self-consistency check against the committed spacecraft samples runs for both.

J2000 · Sun-centered · 2643 samples

Coverage: April 14, 2023 to August 22, 2026