In 1977, the Voyager 1 space probe was launched to study the outer solar system.
The two Voyager space probes have become the longest operating spacecrafts in spaceflight history.
41 years later, Voyager 1 is now 19 Billion kilometres from Earth and travelling at 61,000km/h.
Despite Voyager 1 being the furthest man made object from Earth, we are still able to communicate
with the space probe on a regular basis.
But how far can it go before we can no longer communicate with it?
To answer this, we need to know how Voyager 1 receives and transmits data from 21 Billion Kilometres away.
A 20 KiloWatt signal is transmitted from Earth to Voyager 1 using radio waves.
It takes almost 20 hours for the signal to reach the space probe where it’s sensitive
antenna picks up the signal.
For comparison, it takes the rovers on Mars an average of just 15 minutes to send messages back to Earth.
Voyager starts sending data back to Earth using a 20 Watt signal.
As it travels through space, the signal strength weakens.
And by the time it reaches Earth, the signal is barely detectable.
In order to communicate with objects that are this far away, it doesn’t really matter
how strong the signal is, as long as you have a receiver that is sensitive enough to pick it up.
NASA uses the Deep Space Network which consists of three Antenna complexes equally spaced
around the Earth.
Each complex has a huge 70 metre antenna along with multiple 34 metre antennae which can
be combined to pick up signals that are thousands of times weaker than your standard FM radio signal.
The Deep Space network spends several hours each day listening for faint signals from
Voyager 1, and so far, it continues to talk back to us.
Since our methods for detecting signals has improved drastically over the past 50 years,
there isn’t really a limit on how far we can communicate with objects in Space.
With our current technology, we could reliably communicate with objects that are many light years
away from us, as long as our receivers are sensitive and accurate enough to pick
up the extremely weak signals.
As Voyager travels further and further away from Earth it takes longer to send and receive signals.
The signal strength also gets weaker and data rates become slower making it harder and harder
to communicate with the spacecraft.
Voyager 1 will continue on it’s journey indefinitely, and although there is technically
no limit to how far we can communicate, our communication with Voyager 1 only has a few years left.
Since Voyager 1 is Nuclear powered, it’s electrical power weakens each day.
In 1990, in order to save power, engineers turned off the spacecraft’s camera after
Voyager took the famous “Pale Blue Dot” image, which showed Earth as a tiny blue pixel
against the darkness of space.
Today, only 4 out of the 11 scientific instruments on Voyager 1 are still active.
These instruments are being used to collect data on magnetic fields, solar winds and cosmic rays
outside of our solar system.
In around 8 years, Voyager 1 will completely run out of power and will no longer be able
to keep it’s instruments going.
Scientists will continue to communicate with the space probe and receive the important
information it gathers until it eventually sends its last bit of data and disappears
silently into space, never to be heard from ever again.
So although the end is near for the Voyager space probes, we can appreciate the incredible
journey they have been on and the valuable science they have taught us.
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