NASA’s two Voyager probes have been hurtling towards the farthest corners of the solar system since launching in 1977. In 2012, Voyager 1 became the first man-built object to reach interstellar space, and was followed by Voyager 2 in 2019. NASA expects both spacecraft have enough fuel to last them until 2025, after which their scientific missions will be likely be retired.
Now, after travelling more than 11.6 billion miles (18.8 billion km) into space, it is no easy feat for NASA’s scientists to stay in touch with the Voyagers.
And the only antenna that can communicate with Voyager 2 has been offline since March this year.
The 230ft-wide (70m) Deep Space Station 43 radio antenna in Canberra, Australia, was shut down earlier this year for upgrades which are on track to wrap up by February next year.
The dish-like antenna forms part of a global network of antennas designed to communicate with spacecraft operating beyond the Moon’s orbit.
Since the Station 43 dish went offline, Voyager’s mission operators have only been able to receive health and data updates from the spacecraft.
But on October 29 the scientists managed to successfully reach the spacecraft for the first time since mid-March, testing some of the newly installed hardware.
A series of commands was beamed to the spacecraft from the Station 43 dish, after which Voyager 2 confirmed it had received the transmission.
Among the new upgrades, Deep Space Station 43 is receiving two new radio transmitters.
One of these has not been upgraded in 47 years – longer than the Voyagers have been in space.
Engineers are also upgrading the antenna’s heating and cooling systems, power supply equipment and other electronic components.
The most recent test call to Voyager 2 suggests the work is making good headway to be completed by February 2021.
Brad Arnold, the DSN project manager at NASA’s Jet Propulsion Lab, said: “What makes this task unique is that we’re doing work at all levels of the antenna, from the pedestal at ground level all the way up to the feedcones at the centre of the dish that extend above the rim.
“This test communication with Voyager 2 definitely tells us that things are on track with the work we’re doing.”
The radio dish forms one chain in a link of antenna known as the Deep Space Network (DSN).
The DSN antennas are equally spaced out across the globe, located in Canberra in Australia, Goldstone in California, and Madrid in Spain.
Thanks to their positions, at least one radio antenna in the network can communicate with almost any satellite at any given time.
Voyager 2, however, is an exception to the rule, thanks to its flyby of Neptune’s moon Triton in 1989.
At the time, the spacecraft passed over Triton’s north pole and was deflected on an orbit south of the planetary plane.
As a result, the Deep Space Station 43 antenna is now the only radio dish in the Southern Hemisphere that can reach the spacecraft.
Philip Baldwin, operations manager for NASA’s Space Communications and Navigation (SCaN) Program, said: “The DSS43 antenna is a highly specialised system: there are only two other similar antennas in the world, so having the antenna down for one year is not an ideal situation for Voyager or for many other NASA missions.
“The agency made the decision to conduct these upgrades to ensure that the antenna can continue to be used for current and future missions. For an antenna that is almost 50 years old, it’s better to be proactive than reactive with critical maintenance.”
The radio dish has been in operation since 1972 and has since received a wide array of upgrades.
Its downtime since March, however, is the longest it has been offline in 30 years.