GOONHILLY Earth Station will become home to Cornwall's first permanent planetarium, according to bosses at the site.
Work due to start on the visitor attraction at its base near Helston last year was stalled when a £6.5 million grant from the Government's Regional Growth Fund failed to materialise.
In 2011 ministers approved GES Ltd's bid in principle, with the funds due in January last year.
But GES Ltd now says it had built up people's expectations on the "back of broken promises".
In July, Helston's MP, Andrew George, asked Prime Minister David Cameron to cut through the red tape and investigate what was causing the delay. He said there has been no response despite assurances the project had government support.
GES Ltd director Ian Jones told the West Briton the bid had not been rejected and was still on the table, but he felt "let down" by the Government.
He said the fund was crucial to its plans for the visitor centre and planetarium, to upgrade its antennas and become a co-location centre for other businesses. It would create 150 local jobs.
He said: "We were hoping to open the visitor centre last Easter. We have designs and are waiting to get it off the ground. Goonhilly has an amazing reputation within the science world. It's similar to Concorde and the Red Arrows."
The firm, which controls Sky's satellites, also plans to exercise its exclusive right to buy the lease from BT.
Mr Jones added: "We feel frustrated that we haven't been able to do what we planned.
"We have doubled our business in the past four years and our turnover is now £600,000.
"It's absolutely what we are passionate about and we will make it happen, but we don't want to make promises and let people down."
He said without the government fund it would be paid for from GES's profits, becoming a "slow, laborious project".
Russell Peters, chairman of St Keverne Parish Council, was also disappointed and said the planned science park had "huge spin-off potential" for the area.
He added: "It was fantastic news 12 months ago but since then we've been asking 'when, when, when'?"
Mick Harvey, newly-appointed honorary vice-president of Cornwall Astronomy Society – replacing the late Sir Patrick Moore – said the planetarium would "open people's eyes to the universe and our world", adding: "With Cornwall's recent bad weather, people would actually get to see what's happening in the skies."