Voyager for schools: worksheet
Open the homepage tracker and record its values at the time of your visit. The numbers change, so solutions to live questions explain the method rather than giving one fixed result.
Use your browser's Print command for the worksheet. The answer key is excluded from printing.
Voyager for schools: worksheet
Which spacecraft is farther?
Record the Earth distance of Voyager 1 and Voyager 2 in astronomical units (AU). Which is farther away?
From AU to kilometres
One AU is exactly 149,597,870.7 km. How many kilometres are 10 AU? Then convert Voyager 1's current AU distance and round to the nearest million kilometres.
Waiting for a reply
Write down Voyager 1's one-way signal time. Estimate a round trip by doubling it. Why might the tracker's precise round trip differ slightly?
Launch order
Voyager 2 launched on 20 August 1977, and Voyager 1 on 5 September. Why is Voyager 1 farther away today?
Answer key and methods
- Which spacecraft is farther?
Compare both values at the same moment. Voyager 1 is farther at present; your numbers depend on the observation time.
- From AU to kilometres
10 AU = 1,495,978,707 km. For the live value, multiply the AU number by 149,597,870.7 and round.
- Waiting for a reply
Doubling is a quick estimate. The precise calculation accounts for Earth and spacecraft motion during transmission; it excludes command-processing time.
- Launch order
Voyager 1 followed a faster, shorter route to Jupiter and Saturn. Gravity assists sent the spacecraft along different paths; launch order did not determine their present order.
Answer first, then verify
For these tasks, it depends on the procedure and the correct meaning of the quantities. Read the variable numbers directly from the tracker and always write down the reading time in UTC. You can then use the entry the next time you visit the website.
1. What exactly are we comparing?
For both spacecraft, record the distance from Earth and the distance from the Sun. In each pair, identify the farther spacecraft. Explain the reference point of each distance and why the two quantities must not be confused.
2. Place Voyager in the school model
Use the scale 1 au = 1 m. Read the distance of the selected probe from the Sun in au from the tracker and convert it to model meters. Then determine how many meters one hundredth of au represents. Compare the result with the scaled distances page.
3. Which waiting time can we calculate?
On the communication page, choose a spacecraft and recalculate the timeline. Record the outward signal travel time, the return travel time and their total. Explain why the total does not determine when a real NASA command will be confirmed.
Solutions and explanations of new tasks
- Distances have different origin.
At the distance from the Earth is the origin of the Earth, at the heliocentric distance is the Sun. Verification of the first result requires the reading of both probes for the same moment and the same kind of distance. We do not prescribe a fixed numerical result here.
- The number in au is converted to meters in this scale.
If the written distance is D au, the model has D m. One hundredth of au corresponds to 0.01 m, i.e. 1 cm. The result describes the distance from the Sun; planet sizes are not shown by this model.
- We add two flight times.
The timeline calculates the transmission from Earth to the probe and the instantaneous transmission back. The actual execution of the command, waiting for the connection and sending the telemetry have additional durations that are not included in this calculation. Rounded sub-times may differ by a second from the displayed total during manual summation.
Materials: current tracker, distance model, signal timeline a calculation methodology.
Verified on 2 October 2026: JPL — Horizons System Manual · NASA — Deep Space Network.