science
Voyager 1 is nearly a light-day from Earth. A round trip takes about two days
NASA’s 18 November projection puts one leg of the radio journey at about 24 hours. Here’s how to work out the round-trip signal time and follow the public briefing.
Media credits, sources and reuse details ↓
Voyager 1 lifts off from Kennedy Space Center in Florida on 5 September 1977. This archival photograph shows the launch. NASA/JPL-Caltech/KSC. NASA Photojournal · Media terms.
NASA expects Voyager 1 to reach one light-day from Earth on 18 November. The mission tracker puts the crossing at about 10:16 GMT, when the spacecraft will be about 25.9 billion kilometres away. NASA published its event notice on 10 November. At this check, the crossing was still ahead. NASA announcement · Mission tracker.
The useful way to read the milestone is to follow two clocks. The first starts when a ground station transmits. The second starts only when Voyager sends something back. At this distance, each signal spends about a day travelling.
One day out, one day back
A light-day is the distance light travels in 24 hours. Radio travels at that speed through space. If a spacecraft exactly one light-day away replied the moment a command arrived, the reply would reach Earth around two days after the original transmission. That is a simple travel-time example. It excludes scheduling the transmission, processing the command and waiting for a suitable receiving session.
The 18 November estimate uses distance from Earth. Treat that reference point as part of the measurement when comparing trackers or graphics. A chart of distance from the Sun answers a different question. The milestone describes how far a signal travels and gives no new measure of the connection’s data rate.
What the ground stations do
NASA’s Deep Space Network uses antenna complexes at Goldstone in California, near Madrid and near Canberra. Their locations help stations follow spacecraft as Earth rotates. When you open NASA’s network guide, look for DSN Now to see activity reported by the ground stations. An active link tells you which antenna is working. It still takes time for a radio signal to travel.
Follow the milestone from wherever you are
NASA has listed a public discussion for 19 November at 17:00 in London, 18:00 in Lagos and 19:00 in Johannesburg. Check the NASA live page for the stream or a schedule update. NASA’s 17 November light event is symbolic and follows local sunset. A phone flash marks the occasion for people on Earth. Event details.
The cover comes from the mission’s original launch, almost five decades before this projection. NASA’s label gives the date and the vehicle. For a practical way to read other mission records, see PING!’s guide to the Artemis II lunar archive.
Sources and disclosures
- Disclosure
- Documentation-based reporting with AI-assisted drafting. PING reviewed NASA’s mission tracker, notices and Photojournal record. The milestone and events are future as of 12 November. The two-day example is signal travel time only.
- Declared media rights
- Supplied for permitted editorial use; creator retains rights
- Sources and method
- NASA’s dates are forecasts or programme listings checked 12 November. The distance is Earth-referenced. The round trip is two approximate one-way intervals and excludes operations delay. Cover: Voyager 1 lifts off from Kennedy Space Center in Florida on 5 September 1977. This archival photograph shows the launch. NASA/JPL-Caltech/KSC. Exact unchanged NASA PIA21747 JPEG. https://science.nasa.gov/photojournal/voyager-1-launch-2/ · https://www.nasa.gov/nasa-brand-center/images-and-media/ Cover: Voyager 1 lifts off from Kennedy Space Center in Florida on 5 September 1977. This archival photograph shows the launch.
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