After a tense 34 hours and 48 minutes, the signal finally hit the big antenna at Tidbinbilla, and scientists breathed "a great sigh of data" that one of the furthest-travelled pieces of human artifact in existence was still "awake" and functioning.

"As the clock ticked down, it was kind of an anxious moment waiting for the response," the deep space network's centre manager Glen Nagle said.

"Voyager 2 is now 18.6 billion kilometres away from us travelling at 17 kilometres a second so the lightspeed signal takes 17 hours and 24 minutes each way.

"While we have received one-way data from Voyager, this is the longest period we've gone in which we haven't had a two-way communication with the spacecraft.

"So it's been travelling out there in deep space, cold and alone, for a very long time."

The reason for the hiatus in communication was that Canberra's big DSS-43 communications dish, the only one which can communicate with Voyager 2 because of its distance and location, has been undergoing a much-needed, NASA-funded $4 million refurbishment.

The renovations will be finalised in February but enough of the upgrades have been installed to date for scientists to run tests.

"For a first communication in such a long time we didn't want to send anything too complex so it was a pretty simple command: 'reset onboard clock'," Mr Nagle said.

"And almost a day and a half later we got back: 'clock reset'.

"That was a real 'phew' moment for us and for the mission team back in Pasadena, California.

"Basically for us, it's like Voyager saying 'hello, I'm still here'."

Launched in 1977 to study the outer planets, Voyager 2 has been travelling for 43 years and has ventured now into a part of interstellar space which is three times further out than the orbit of Pluto. The plucky old spacecraft is still travelling 1.4 million kilometres a day away from us.

But here's the mind-boggling part: given the direction it is travelling, Voyager 2 won't reach the closest star to it - Wolf 359, in the Leo constellation - for another 40,000 years.

Meanwhile, the team at the Tidbinbilla complex are pushing ahead with the big dish's return to full function in readiness for its participation in two upcoming Mars programs.

The first is the NASA Perseverance rover mission which will drop a six-wheeled vehicle on the surface of the red planet's Jezero Crater in around 100 days' time.

The second is a United Arab Emirates-funded mission, the Hope orbiter, which will study storms, weather events and various cycles in the Mars atmosphere.

After that, there's NASA's plan to put astronauts back on the Moon by 2024 as part of Mission Artemis.

While its education and visitor programs had to be curtailed due to COVID-19, the Tidbinbilla deep space complex hopes to re-open to the public again in December.