Plans for legislation to enable the development of the UK's first commercial spaceports have been delayed by Brexit, BBC Scotland understands.
The UK government announced in the Queen's Speech in May last year that it would bring forward a bill.
Two Scottish sites have announced plans to bid for the spaceport licences - Prestwick airport and Machrihanish.
However, the government said there was currently no timetable for the introduction of the bill.
There is a growing market for launching small or nano satellites which could be used for communications such as broadband.
The Scottish sites want to tap into this market and also lay down the infrastructure for future developments such as space tourism.
Legislation concerning space is reserved to Westminster.
The UK's government's Department for Transport (DfT) is responsible for the Modern Transport Bill, which would set regulations for driverless cars as well as allowing UK aerodromes to access space.
It told BBC Scotland that it had been working hard on the bill but parliamentary time had been limited by events such as Brexit and the discussions over triggering Article 50.
A spokeswoman for the DfT said: "The final date for the introduction of the Modern Transport Bill will be announced in due course.
"We are creating the legislative and regulatory framework to allow the development of spaceports in the UK. It will be for the market to decide where the first spaceport will be established."
Prestwick airport's director of spaceport development Richard Jenner said it had done a lot of work in preparation for applying for a spaceport licence.
He said the airport was now waiting for the regulations to "clarify" what was needed to become a spaceport.
He told BBC Scotland: "If the delay's only short I don't think it's a big problem at all.
"As I understand it, the UK government are still very committed to launching the first rocket by 2020 and they are very keen for us to progress so I don't think there's any change in their intent.
"I think it's just a delay due to the parliamentary process."
Prestwick commissioned a report in 2015 which said it would cost between £1m and £3.5m to get the airport to the standard to meet US spaceport regulations.
Mr Jenner said the airport would need to make some modifications but it was confident it already had most safety measures in place.
Also based at the South Ayrshire airport is a company called Orbital Access, which is developing a hybrid aeroplane and rocket system.
It plans to use a wide-body carrier aircraft, with special modifications to carry a rocket under its body.
The launcher rocket would be released at altitude and fired into space to deliver the payload.
This system could be used at any of the spaceports which get a licence.
Campbeltown airport at Machrihanish on the Kintyre peninsula has also announced a technical partnership which is looking at how to develop a spaceport.
The Machrihanish plan is being put together by DiscoverSpace UK, which has signed a memorandum of understanding will tech firms QinetiQ and TelespazoVEGA.
DiscoverSpace UK's managing director, Tom Millar, told BBC Scotland it would look to develop its plans over the next six months.
Machrihanish has a very long runway and is not close to large settlements, which meets the original government criteria.
Mr Millar also said that the airspace above the runway had very few commercial flights, taking away the concern over interference with passenger aircraft.