Two more Canadian astronauts are headed into space, the government will announce on Tuesday as it commits about $350-million to the International Space Station to secure a continued presence in the orbiting research laboratory.

This pledge will ensure that both Lieutenant-Colonel Jeremy Hansen and David Saint-Jacques, the two Canadians training as astronauts, can make the trip to the station, which circles the Earth at an altitude of about 400 kilometres.

One visit will take place before 2019, and the second by 2024, sources said. Countries earn credit toward trips to the space station based on their contributions to building and maintaining it.

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The last Canadian in space was Chris Hadfield, the first Canadian to command the ISS. He left the space station in May, 2013.

Industry Minister James Moore will extend Canada's support for the space laboratory until 2024 in an announcement at the Canadian Aviation and Space Museum in Ottawa.

He is expected to pledge as much as $350-million over four years. The Canadian Space Agency's planned spending for the current fiscal year is more than $83-million, and this new pledge from Canada is expected to be a similar amount on a yearly basis.

Canada is the third of five ISS partners to announce a continuation of support until 2024. The Conservatives plan to underline this on Tuesday by framing the commitment as the fruits of a balanced federal budget that now frees up Ottawa to invest in other areas.

Under the international treaty that governs ISS participation, a country's funding commitments guarantee at least one space flight for an astronaut.

The countries partnering to run the orbiting laboratory invest the money in supplies and equipment and resources at home that the ISS uses.

The government is also providing $4-million to support four medical research projects in the space laboratory that are being conducted this fall. The experiments, led by Canadian universities, will test the effects of weightlessness on the human body.

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In related news, Ottawa will invest up to $1.9-million over two years in the Alpha Particle X-Ray Spectrometer, Canada's science instrument on board the Curiosity Mars Rover. The device measures the abundance of elements and chemicals in rocks and soil.

Lt.-Col Hansen, a CF-18 pilot, and Dr. Saint-Jacques, a physician, will be on hand Tuesday to answer questions about their training and visiting the International Space Station.

The orbiting laboratory is as wide as five National Hockey League rinks and as long as one NHL rink.

Last week, the Canadian government announced it is also exploring the possibility of partnering with Israel on space missions.

The Canadian Space Agency and the Israel Space Agency are conducting studies on the proposal. They both seek to develop advanced applications for satellite communications and position Canada and Israel as leaders in this field.

A private company such as Elon Musk's SpaceX may be ready to take astronauts to the International Space Station by the time Canada's turn arrives. Both Boeing and SpaceX have contracts to transport people to the laboratory, but must pass certification tests.

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NASA retired its space shuttles in 2011.

Nine Canadians have flown in space, including eight astronauts and Guy Laliberté, co-founder of the Cirque du Soleil.