Rosetta

Trajectory record

Precise trajectory

Sun-centred J2000 states sampled offline from NASA/JPL NAIF SPICE kernels with geometric (NONE) aberration correction, using the Rosetta orbiter's reconstructed cruise ephemeris ORHR_______________00122.BSP - the ESA/ESOC solution the archive describes as spanning the cruise phase from launch to the comet rendezvous manoeuvre, and as superseding all earlier versions - with the Martian system ephemeris MAR097_030101_170101_V0001.BSP furnished for Mars's own body centre, which DE440s does not carry (it holds the Mars system barycentre alone), and DE440s furnished last so planetary positions match the committed body ephemerides. Sampling is weekly across the cruise and tightens to 60 s within six hours of the Mars closest approach. The record covers only the cruise phase, from the kernel's first tracked state about two hours after launch to 2014-08-04, some seventy-five minutes before that kernel's coverage ends and two days before the arrival at Comet 67P/Churyumov-Gerasimenko this record's events describe. The comet phase is deliberately not included: it lives in separate orbit-determination files whose own archive documentation warns that they and their companion comet ephemerides carry one-second discontinuities within which the relative orbit between spacecraft and comet is significantly wrong, and a rendezvous has no closest approach for this pipeline's encounter model to find. The single committed encounter is the 25 February 2007 Mars gravity assist, the mission's only planetary swing-by that was not of Earth. Its published figure is a pericentre radius rather than an altitude, and the source distinguishes the two itself: Budnik and Morley's ESA/ESOC navigation paper gives the nominal pericentre altitude as 250 km above the surface of Mars in its introduction, and its table of swing-by parameters as determined after the swing-by gives a Pericentre Radius of 3648.084 km. The two readings are 3,396 km apart - Mars's own equatorial radius, read from the same pck00011.tpc this dataset furnishes - so which one is meant is not a rounding question: the computed centre distance of 3,649.087 km sits 1.003 km from the radius reading and 3,395 km from the altitude reading. The paper's own printed osculating elements agree, since its semi-major axis of -551.986 km and eccentricity of 7.609013 give a conic pericentre of 3648.083 km about the focus, which is Mars's centre of mass. The epoch comes from a second source rather than that one, because the paper prints the pericentre passage in TDB (01:59:04.46) and this catalogue records UTC; ESA's own Rosetta status report for May 2007 gives 1:57:59 UTC, and converting the paper's TDB instant through the furnished leapseconds kernel lands on 01:57:59.275 UTC, so two independently published epochs agree to 0.3 s. The computed closest approach falls at 01:57:59.305 UTC. The remaining 1.003 km of distance difference is accounted for rather than unexplained. The same archive also ships ORMR_______________00052.BSP, the dedicated Mars-flyby solution ESOC delivered four days after the swing-by, and that file reproduces the published 3648.084 km to 0.0004 km, which most likely makes it the orbit determination the published table was computed from - an inference from the kernel's own creation date and that agreement, since the paper names no kernel, so it is not recorded as a published fact. The archive states that it is superseded by the cruise kernel used here, so this dataset follows the archive's own latest solution and records the difference between the 2007 short-arc and the 2011 long-arc reconstruction, rather than selecting the kernel that flatters the published number. Mars's system barycentre and its body centre are the same point to 0.00004 km at this encounter, Phobos and Deimos being negligible against Mars, so the barycentre offset the viewer draws against is zero to the precision recorded.

J2000 · Sun-centered · 1778 samples

Coverage: March 2, 2004 to August 4, 2014