The radio telescopes at Parkes and Narrabri may shut within two years “without substantial, long-term external investment”, the chief of the CSIRO’s space research division has warned.

It was expected that funding for the telescopes would diminish as the next-generation square kilometre array (SKA) telescope comes online between 2020 and 2025.

But the head of the CSIRO astronomy and space science department, Lewis Ball, said the $114m cut to the agency’s funding in the May federal budget “ramps up the pressure and means that we have to make significant changes right now”.

“This is a budget cut for the current financial year, which we only became aware of when the federal budget was announced on 13 May,” he said. “So we’re dealing with a $3m cut, amounting to 15% of our budget, on six weeks’ notice.”

He told the Australian Astronomical Society this week that “without substantial, long-term external investment”, the agency would have to “cease funding of one or more of Parkes and the Australian telescope compact array [at Narrabri]”.

The future of the two centres, which astronomers inside CSIRO said were “at the peak of their ability”, was already uncertain, because federal government funding under the national collaborative research infrastructure strategy was due to run out in mid-2015.

The government pledged $150m in the federal budget to fund key research infrastructure until mid-2016, but accepted a recommendation from the Commission of Audit to review the funding after that date.

Ball said it was uncertain how much of this additional funding would be allocated to Parkes, which famously beamed the 1969 moon landings to the world, and Narrabri, or whether their funding would survive the review.

He said the confusion highlighted deeper problems with the “hand-to-mouth” way Australia funded its major research equipment, where money was renewed every one or two years, “just in time to stop everybody falling off the cliff”.

The CSIRO has already announced that it will “cease long-term upgrades” of the centres to help find the required $3.5m in savings. In March the agency announced that the 22-metre wide Mopra radio telescope at Coonabarabran, the third component of the Australia telescope national facility, will stop being funded around September 2015.

A national organiser with the CSIRO staff association, Paul Girdler, said it appears Parkes and Narrabri, both in NSW, were being “cannibalised to prop up the SKA, and government funding cuts have been a key element in causing this to happen”.

Comprising thousands of small antennas in South Africa, New Zealand and Australia, linked by fibre-optic network, the SKA will be the world's largest radio telescope, able to detect radio waves with 50 times the sensitivity of existing facilities. The Australian component alone will process data equivalent to the whole of the world wide web every hour.

The array will be powerful enough to see back 13bn years in time and detect energy emitted when the first black holes and stars were formed.

Funding the SKA was the agency’s priority, because it was part of a new generation of radio telescopes that would largely supersede the capabilities of existing facilities.

The CSIRO had hoped to eventually find and fund new scientific roles for the telescopes at Parkes and Narrabri, but Ball said the budget cuts “require changes to be much more accelerated”.

“It’s obviously better to make a staged and planned transition, and you can’t plan if you don’t know what your funding is until six weeks out from the financial year. You can’t plan on a timescale of six weeks, you can only react,” he said.