Solar System Simulator · Mission · Voyager 1
Voyager 1's trajectory, from 1977 to today
Launch on 5 September 1977, swing past Jupiter and Saturn, and coast out past the heliopause — flown on real gravity rather than a drawn path, with the real mission's milestones shown alongside.
The route
Voyager 1 left Earth on 5 September 1977 on a Titan-Centaur, about 10 km/s faster than Earth itself moves (the simulator's launch solves to 10.1). It reached Jupiter in early 1979 and passed 349,000 km from the planet's centre on 5 March 1979 — under five Jupiter radii. That flyby did two things at once: it bent the path toward Saturn and, by stealing a little of Jupiter's orbital motion, threw the probe outward faster than any rocket had. On 12 November 1980 it passed Saturn at 184,000 km, took its Titan photographs, and left the plane of the planets — heading up and out, above the Sun's escape speed, never to return.
The simulator flies the same plan on its own physics. It places the four giant planets at their 1977 positions, solves a 1.5-year transfer to a point just behind Jupiter, and then integrates the spacecraft through both encounters with the planets' real masses and radii. In that flight the probe passes Jupiter about 6 radii out in February 1979, Saturn about 3 radii out in November 1980 — the same month as the real pass — and leaves Saturn at 20.5 km/s above escape.
Milestones, real mission
| When | Event | Distance |
|---|---|---|
| Feb 1990 | Pale Blue Dot — the camera turned home | 40 AU |
| Feb 1998 | Passes Pioneer 10 — most distant human-made object | 69 AU |
| Dec 2004 | Termination shock — the solar wind stalls | 94 AU |
| 25 Aug 2012 | Heliopause — interstellar space | 122 AU |
| September 2026 | Still transmitting; gaining about 3.6 AU a year | ~172 AU |
The simulator's inlay stamps each of these as the mission clock reaches the real date, next to the distance its probe has reached, so you can see where the two diverge. They do diverge: after 49 years the simulated probe is about 206 AU out, some 20% beyond the real 172. The sequence — escape after Jupiter, the Saturn month, the long coast — is right; the exact distance is not, because the simulator is flat (the real Saturn pass bent the path 35° out of the plane of the planets, which also cost speed) and because it starts from the giant planets' rounded 1977 positions on circular orbits.
Where is Voyager 1 now?
About 172 AU from the Sun as of September 2026 — 25.7 billion km, or 23.8 light-hours, so a command sent today arrives tomorrow. It is moving at roughly 17 km/s, while the Sun's escape speed at that distance is under 3 km/s: gravity can slow it, but never turn it around. The figure here is the simulator's own estimate — 121.6 AU at the heliopause crossing plus 3.57 AU for every year since — and the mission inlay computes it fresh from today's date whenever you open it.
Voyager 2 took the scenic route
Voyager 2 launched first, on 20 August 1977, on a slower path that let it visit all four giants: Jupiter on 9 July 1979 (641,000 km), Saturn on 25 August 1981 (161,000 km), Uranus on 24 January 1986 (107,000 km) and Neptune on 25 August 1989 (29,000 km from the planet's centre — about 5,000 km above the cloud tops). It crossed the heliopause on 5 November 2018 at 119 AU and is now about 145 AU out at 15.4 km/s.
The simulator flies Voyager 2 too — Jupiter, Saturn and Uranus, with the small course-correction burns the route needs (105 m/s in total, close to the real mission's budget), reaching about 143 AU at 15.0 km/s today, against the real 145 at 15.4. It cannot close on Neptune: a four-flyby chain is so sensitive that it needs the giants' true 1977 positions, not the rounded circular ones the sandbox starts from. The mission log says so rather than faking the fourth encounter.
What the simulator does
- Reset, then place Jupiter, Saturn, Uranus and Neptune at their 1977 longitudes, with Earth at the launch window.
- Solve the departure (a 1.5-year Lambert transfer at 10.1 km/s over Earth) aimed at a point just behind Jupiter.
- Integrate the spacecraft with adaptive sub-steps near each planet, so passes a few radii out are resolved properly — a crash counts as a crash.
- Measure each flyby as the change in the probe's orbital energy about the Sun, and stamp the real mission's milestones as the clock reaches them.
Questions people ask
Where is Voyager 1 right now?
About 172 AU from the Sun in September 2026 (25.7 billion km, 23.8 light-hours), gaining roughly 3.6 AU every year. The number above extrapolates from the 2012 heliopause crossing; the simulator's mission inlay recomputes it from today's date.
Has Voyager 1 left the solar system?
It crossed the heliopause on 25 August 2012, where the solar wind gives way to interstellar plasma, so by that definition yes. The Sun's gravity still reaches it, and the Oort cloud lies far beyond — but at 17 km/s it is well above escape speed and will never come back.
Why does the simulator end up at 206 AU instead of ~172?
Three approximations: a flat plane (the real Saturn pass bent the path 35° north and cost speed), circular orbits for the giant planets at rounded 1977 positions, and a slightly sharper Saturn encounter. The order of events and the escape are right; the final distance overshoots by about 20%.
How fast is Voyager 1 going?
About 17 km/s relative to the Sun today. The simulated probe reads a little over 20 km/s for the reasons above. Either is many times the local escape speed of under 3 km/s.
Keep going
Every number on this page comes from the simulator's own physics or the real mission record it is checked against. Where the simulation and reality differ, the page says so.