Launched by NASA on September 5, 1977, to study the outer solar system, the Voyager 1 is the furthest human-made object from Earth. As of January 28, 2021, the space probe is more than 14,155,490,863 miles (22,781,054,287 km) away from our home planet. It is also moving away at a speed of 38,026.77 mph (61,198.15 km/h) relative to the Sun.

Despite that huge distance (even the light covers that distance in more than 21 hours), thanks to NASA’s Deep Space Network (DSN, see notes 1), we can still communicate with it (also with its sister, Voyager 2). But how far can Voyager 1 go before we lose communication?

The video published by the Primal Space channel below looks at how we communicate with Voyager and when it will eventually stop receiving our signals.

The two Voyager probes are the longest operating spacecraft in the history of space exploration. How far can Voyager 1 go before we lose communication? This video looks at how we communicate with Voyager and when it will eventually stop receiving our signals.

How long we can communicate with the Voyager 1?

Using the Deep Space Network, NASA transmits a 20 kW radio signal from Earth. It takes more than 21 hours for the signal to reach Voyager 1 (so it is more than 21 light-hours away from the Earth). The space probe’s sensitive antenna picks up the signal and replies using a 20-watt signal. It takes another 21+ hours to reach the Earth and as the signal travels through space, it weakens. By the time it reaches Earth, it’s barely detectable – but the DSN is able to detect it.

Positions of the five space probes which leaving the solar system

Related: Five space probes leaving the solar system (for now)

Theoretically, there isn’t really a limit on how far we can communicate with objects in space – as long as they reply back to us. With our current technology, we could reliably communicate with the Voyager 1 for thousands of years, even if it’s many light years away from us.

Despite that, we can communicate with Voyager 1 only a few years more. The reason is: the probe’s nuclear-powered (see notes 2) electrical supply weakens each day.

Voyager 1 in Deep Space (Artist Conception)
Voyager 1 in Deep Space (Artist’s Conception). Since the Voyager spacecrafts are identical, it could be Voyager 2, as well. The Voyager spacecrafts were built by JPL, which continues to operate both. JPL is a division of Caltech in Pasadena. California. The Voyager missions are a part of the NASA Heliophysics System Observatory, sponsored by the Heliophysics Division of the Science Mission Directorate in Washington. Image: NASA.gov

Voyager 1 and the “Pale blue dot”

Back in 1990, in order to save power, engineers turned off the spacecraft’s camera. But, before that, it was commanded by NASA to turn its camera around and to take a photograph of Earth across a great expanse of space, at the request of Carl Sagan.

Taken from a record distance of about 6 billion kilometers (3.7 billion miles, 40 AU) from Earth, the photo known as the Pale Blue Dot. In the photograph, Earth is shown as a fraction of a pixel (0.12 pixel in size) against the vastness of space.

The “Pale Blue Dot” is still the farthest image of Earth we’ve ever taken (as of January 2019).

Voyager 1 Pale Blue Dot
This narrow-angle color image of the Earth, dubbed ‘Pale Blue Dot‘, is a part of the first-ever ‘portrait’ of the solar system taken by Voyager 1. “Consider again that dot [Earth]. That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor, and explorer, every teacher of morals, every corrupt politician, every ‘superstar,’ every ‘supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.”  –Carl Sagan, Pale Blue Dot: A Vision of the Human Future in Space

But the old probe still amazes us: on November 28, 2017, a set of thrusters aboard it successfully fired up for the first time since November 1980, after 37 years without use.

Today, only 4 out of 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.

On August 25, 2012, Voyager 1 became the first spacecraft to cross the heliopause (see notes 3) (the vast, bubble-like region of space that surrounds and is created by the Sun) and enter the interstellar medium.

Voyager 1’s extended mission is expected to continue until around 2025 when its radioisotope thermoelectric generators will no longer supply enough electric power to operate its scientific instruments. At that time, it will be more than 15.5 billion miles (25 billion km) away from the Earth.

Scientists will communicate with Voyager 1 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 again.

Notes

  1. The Deep Space Network (DSN) is a worldwide network of U.S. spacecraft communication facilities, located in the United States (California), Spain (Madrid), and Australia (Canberra), that supports NASA’s interplanetary spacecraft missions. Each complex has a huge 70-meter antenna along with multiple 34-meter antennae which can be combined to pick up signals that are thousands of times weaker than a standard FM signal.
  2. Voyager 1 does not use a nuclear reactor to power itself. It uses three RTG units – (Radioisotope Thermal Generator), which converts the heat from decaying plutonium into electricity using Peltier devices. It is not very fancy, has no moving parts, and is very reliable, but it produces a lot less power than a nuclear reactor.
  3. The heliosphere is the vast, bubble-like region of space which surrounds and is created by the Sun. In plasma physics terms, this is the cavity formed by the Sun in the surrounding interstellar medium. The “bubble” of the heliosphere is continuously “inflated” by plasma originating from the Sun, known as the solar wind. Outside the heliosphere, this solar plasma gives way to the interstellar plasma permeating our galaxy. Radiation levels inside and outside the heliosphere differ; in particular, the galactic cosmic rays are less abundant inside the heliosphere, so that the planets inside (including Earth) are partly shielded from their impact. The word “heliosphere” is said to have been coined by Alexander J. Dessler, who is credited with first use of the word in the scientific literature.

Sources

M. Özgür Nevres
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