# Mission trajectory provenance

Imported September 22, 2026 from [NASA/JPL Horizons](https://ssd.jpl.nasa.gov/horizons/), with UT geometric vectors in AU and AU/day, Sun-centered ecliptic J2000 / ICRF. The browser fetches only local static assets; it makes no Horizons requests. [Horizons documentation](https://ssd.jpl.nasa.gov/horizons/manual.html).

| Journey | Included UTC/UT coverage | Source character |
| --- | --- | --- |
| Voyager 1 | 1977-09-05 14:00 – 2026-09-21 00:00 | Mission-design path, then Jacobson's 2022 refit of 1981–1992 tracking and prediction |
| Voyager 2 | 1977-08-21 00:00 – 2026-09-21 00:00 | Mission-design path, then Jacobson's 2022 refit of 1989–1992 tracking and prediction |
| New Horizons | 2006-01-20 00:00 – 2026-09-21 00:00 | Concatenated New Horizons / KinetX navigation solutions, reconstructed and predicted; current header gives a July 20, 2026 tracking cutoff |
| Webb | 2021-12-25 14:00 – 2026-09-21 00:00 | Goddard Flight Dynamics Facility reconstructed solutions through September 20, 2026, with prediction afterward |

These are included sample limits, not claims of all available Horizons coverage. Launch ascent is omitted. The simulator does not independently integrate maneuvers, attitude, or station keeping. Every asset includes original query URLs, SHA-256 response checksums, source headers and withheld-midpoint interpolation checks. Display tolerances are 3,000 km position and 0.25 km/s velocity; these are not estimates of mission uncertainty. Planet/system vectors are sampled independently. Pluto uses the system barycenter; Arrokoth uses Horizons target 2486958, the New Horizons mission-target solution.

Voyager 1 holds its previous sample across 1980-12-31 23:59 – 1981-01-01 00:00. Voyager 2 holds across 1989-08-29 07:59–08:00; a diagnostic 30-second Horizons grid brackets its source discontinuity between 07:59:00 and 07:59:30 UT. These gaps are not drawn as traveled segments. Neither source seam is a physical jump or maneuver.

## Milestones

- [Voyager 1 mission history](https://science.nasa.gov/mission/voyager/voyager-1/).
- [Voyager 2 planet flyby dates](https://science.nasa.gov/mission/voyager/voyager-2/). UI anchors are midnight on those dates, not precise closest-approach instants.
- [Voyager interstellar mission](https://science.nasa.gov/mission/voyager/interstellar-mission/) supplies **November 5, 2018** for Voyager 2's heliopause crossing. Some dates in the general mission page and Horizons background text conflict; the dedicated account is used for this event, not the announcement date.
- [New Horizons mission history](https://science.nasa.gov/mission/new-horizons/). Encounter times also appear in its retained Horizons header: Jupiter 2007-02-28 05:43 UT, Pluto 2015-07-14 11:49:57 UT, Arrokoth 2019-01-01 05:33 UT.
- [Webb insertion burn](https://science.nasa.gov/blogs/webb/2022/01/24/orbital-insertion-burn-a-success-webb-arrives-at-l2/): the timeline anchors just after the approximately five-minute burn begun at 19:00 UT on January 24, 2022.

## Webb's reference frame

[NASA's orbit explainer](https://science.nasa.gov/mission/webb/orbit/) describes a looping orbit near L2, not a spacecraft parked at a point. The local view translates to Earth and rotates around the ecliptic pole by Earth's azimuth. The Sun's projected direction stays fixed; its small out-of-plane motion and changing distance remain. Each historical trail sample is transformed using Earth's position at that sample's time. This preserves distances and shows the imported path, not a synthetic ellipse. Sun-relative speed is always measured in the original inertial frame.

The L2 marker is an explicitly approximate point 1.5 million km beyond Earth along the Sun–Earth direction. It is not a computed equilibrium for an N-body system, a physical object, or a new gravity source. The camera and sky transform with the view. All markers remain enlarged for visibility. No NASA or partner endorsement is implied.