The UK Space Agency is seeking funding and proposals for science and technology experiments for what would be the first British space mission next year.
Four UK astronauts will fly to the International Space Station in late 2025 as part of the planned commercially funded mission in collaboration with US space travel specialist Axiom Space.
The agency today put out calls for up to £15 million of grant funding for experiments to be carried out on the flight.
Proposals are sought from scientists, inventors and businesses about how to "maximise the benefits of a mission in the near term", the agency said.
In October the UK Space Agency signed an agreement with Axiom to pursue a commercially-sponsored UK astronaut mission.
Axiom specialises in training and dispatching private and governmental astronauts for missions to the ISS in collaboration with SpaceX, with its third mission completed in January.
"We want to keep the UK space sector at the forefront of scientific discovery and technological innovation, so this has been front and centre of our work with Axiom Space since October," said Annelies Look, the agency's deputy CEO.
"To deliver the maximum potential benefits to the UK, we are opening funding calls for science experiments and technology demonstrators today, ahead of the potential UK astronaut mission."
A final green light for the mission still requires an agreement between the UK Space Agency, Axiom and the European Space Agency (ESA).
UK minister for space Andrew Griffith said the funding calls "mark a significant stride in our collaborative mission with Axiom Space" and that UK businesses have "huge potential" to play an important role in space exploration and the development of new technologies.
Talks with potential financial backers of the mission have already begun, according to previous comments from Axiom, which has itself won US$2 billion worth of contracts since it was founded in 2016.
The announcement comes a day after the space agency said it plans to move to new headquarters this summer at the Harwell Science Campus space cluster in Oxfordshire to better "embed" itself with the commercial space industry.
Around 100 organisations are located at the Harwell Campus, which is trying to position itself as an international space hub.