Data and sources

How the current value is calculated

The positions and velocities of both spacecraft come from JPL Horizons. We continuously interpolate values for the current time from those data.

This is not live spacecraft telemetry, but a calculation based on their known trajectories.

Four different quantities

• Distance from Earth: how far the spacecraft is from Earth.
• Distance from the Sun: how far the spacecraft is from the Sun.
• Speed relative to the Sun: how fast the spacecraft is moving relative to the Sun.
• Change in distance from Earth: how quickly the distance between spacecraft and Earth is increasing or decreasing.

Signal travel time

Signal time is based on the positions of Earth and the spacecraft at transmission and reception. We report both one-way and round-trip time.

Limitations

Trajectory data may be refined over time. The historical map is approximate, especially around planetary flybys, and we do not extrapolate beyond the available period.