The Search for Extraterrestrial Intelligence (SETI) Institute, had to shut the $30m (£18.3m) Allen Telescope Array in April.
Donors, including actress Jodie Foster, raised more than $200,000 (£122,000).
The 42 radio telescopes, in northern California, search space for potential signals from alien life forms.
Ms Foster was one of more than 2,400 people who contributed to the fund to save the Allen Telescope Array. She played the lead role of an astronomer looking for evidence of aliens in the 1997 film Contact.
In a statement on the fund-raising website she explained her support: "The Allen Telescope Array could turn science fiction into science fact but only if it is actively searching the skies."
Another donor was the Apollo 8 astronaut, Bill Anders.
The SETI Institute says the fund should be enough to keep the telescopes operating until the end of the year, though the plan is still dependent on the institute receiving money from the US Air Force to track space debris that could damage satellites.
SETI Institute Astronomer Seth Shostak told BBC News, the deal with the Air Force is not yet done but he said he is fairly confident it will go through. Even then the money will need to be ratified by Congress and so there may be a delay.  He hopes the array will re-open in September or October.
Thomas Pierson, SETI chief executive, agreed that a deal with the Air Force, combined with the donations, should allow the array to start listening for space chatter once again.
He said: "For those who are interested in understanding whether intelligent life might be out there elsewhere in our galaxy, the Allen Telescope Array and our SETI team doing the research are the best bet."
The array began operating in 2007 and is named after its major benefactor, Paul Allen, co-founder of Microsoft. It consists of 42 dish-shaped antennas which work as a single radio telescope.
It is part of the Hat Creek Radio Observatory, run by the University of California, Berkeley. Originally the array was a joint project between SETI Institute and the UC Berkeley Astronomy Laboratory but Berkeley had to pull out because of the loss of National Science Foundation grants and state budget cuts.
SETI is hoping to raise more money to contribute to the $2.5m (£1.5m) annual operating and staffing costs of the telescopes and keep them going beyond the end of this year. Ultimately the plan is to use the array to observe planets outside our own Solar System.
Dr Shostak said: "People still think this very fundamental question - is there somebody out there as intelligent or more so than us - is important and worth doing."
The array also contributes to research into black holes, pulsars and magnetic fields in the Milky Way.
Telescopes looking for extra terrestrial intelligence should re-open within weeks after donors replaced income lost in public funding cuts.