Reference-frame duration
--days
Departure to orbital insertion
Earth–Proxima b Transit Trajectory
Explore the transit from Earth-Moon L1 to a circular orbit 200 km above Proxima b, with continuous 1 g acceleration.
DEPARTUREEarth-Moon L1PROPER ACCELERATION9.80665 m/s2ARRIVAL ALTITUDE200 km
DEPARTURE DATES / 2028-2040
Departure-date overview
Illustrative daily estimates at continuous 1 g. Calculate a departure below for a refined trajectory and a comparison of both arrival directions.
Loading departure-date overview...
Select a date on the graph to inspect its estimated timings.
| Lowest cost / departure UTC | Arrival UTC | Reference days | Onboard days | Cost / m/s |
|---|---|---|---|---|
| Loading daily estimates... | ||||
The five lowest-cost daily estimates are listed above. Gaps mark unavailable estimates. This overview assumes counter-clockwise arrival; detailed calculations can compare both directions. Select a date and calculate it below to update the displayed trajectory.
01 / SINGLE TRANSFER
Define departure
Choose a departure time to calculate arrival, or an arrival time to calculate departure. The search minimizes onboard duration and may take several minutes.
The search always minimizes onboard duration. “Select best direction” compares both arrival directions and chooses the lower propulsive cost: integrated proper thrust acceleration (m/s) = 9.80665 × onboard seconds. At continuous 1 g, these two criteria are equivalent.
Ready to calculateSelect a departure date to calculate a transfer candidate.
02 / TRANSFER SOLUTION
Flight parameters
Spacecraft duration
--days
Elapsed onboard proper time
Arrival date / UTC
--
Circular equatorial orbit at 200 km
Maximum speed
--% c
Relative to the calculation reference frame
Propulsive cost
--m/s
Integrated proper thrust acceleration
Numerical sensitivity
--
Numerical solution assessment
Velocity profile
REFERENCE-FRAME ELAPSED TIMECalculate a transfer to inspect its velocity profile.
Trajectory events
UTC| Event | Date and time |
|---|---|
| No transfer calculated. | |
Key events along the calculated flight, shown in UTC.
TRAJECTORY / SPATIAL VIEW
Explore the transfer in 3D
Calculate a transfer to explore its path through space.
TransferBody transitExtended guideSelected state
Drag to rotate; Shift-drag to pan; scroll to zoom.
--
Reference elapsed--
Onboard elapsed--
Earth altitude--
Earth-relative speed--
The trajectory is shown at separate physical scales so its departure and arrival geometry remain visible.
Geometric simultaneous positions in ICRF axes; no light-time or apparent-sky effects. Distances are to scale within each view. Small body and spacecraft markers are enlarged for visibility; Proxima b has its physical radius in the Proxima b view. Dashed tracks show body motion during the displayed transit. Faint dotted extensions add up to ten times the dashed track length; the combined track stops at one circuit.
03 / DEPARTURE WINDOWS
Compare departure dates
Rank departure dates by shortest onboard duration, using the arrival-direction setting selected above.
Preparing comparisonLoading the selected departure interval.
No departure windows calculated.
SHORTEST ONBOARD TIME FIRST| Departure / UTC | Arrival / UTC | Reference days | Onboard days | Cost / m/s | Above best / s | Solution |
|---|---|---|---|---|---|---|
| Select an interval and calculate departure windows. | ||||||
Results compare the sampled departure dates. Select a result to calculate its detailed trajectory. A search cannot guarantee the best departure over every possible date.
Calculation basis and interpretation
Flight assumptions
The spacecraft departs Earth-Moon L1 with its existing position and velocity. It maintains 1 g proper acceleration (9.80665 m/s2), with a thrust direction that can change throughout the flight. Arrival is a circular equatorial orbit 200 km above Proxima b; the approach must remain above that altitude. The lower-cost arrival direction is selected by default.
Propulsive cost is the accumulated thrust acceleration over onboard time. At continuous 1 g, the lowest cost also gives the shortest onboard duration. This measure is not a fuel mass or a conventional velocity change. Reference-frame duration uses an external clock; onboard duration includes special-relativistic time dilation.
Distances and body positions
The assumed Sun-Proxima distance is 4.246460140 light-years. Solar System departure positions use NASA/JPL ephemerides. Supported UTC departures run from 2 January 1962 to 30 November 2150, subject to data availability. Proxima b's 7,010 km radius, equatorial orientation, orbital phase and the system's circular planetary orbits are model assumptions, not a measured arrival ephemeris.
Solar System position data: NASA/JPL.
Scope and accuracy
This is an illustrative trajectory calculation. It combines special-relativistic motion with approximate Newtonian gravity near departure and arrival. Gravity during the intervening transfer, gravitational clock corrections, stellar reflex motion, Alpha Centauri A/B and unmodelled moons are omitted. Stellar centers are fixed in the adopted model.
Results depend on the assumed stellar distance and planetary motions; numerical precision does not represent physical arrival accuracy. Calendar dates use a UTC-based reference clock. The numerical search finds a feasible candidate and does not guarantee the globally shortest or lowest-cost trajectory.