The one-way plan to send people to Mars has been slammed by Australia’s first NASA astronaut. He also cast doubts over the entrepreneurial project’s cost and raised the question whether sending people to Mars is “morally defensible.”

Astronaut Andy Thomas was addressing the World Science Festival in Brisbane when he made his statements. Thomas said he was “unimpressed with Mars One,” which is a corporate-funded mission to the Red Planet. The mission aims to make a start in 2024 at a cost of less than $9 billion, reports Brisbane Times.

“It (the cost estimate) is so low as to be laughable. We don’t know how to build a habitat that can sustain a crew for an outbound mission and on Mars indefinitely. I don’t think it’s morally defensible to send crews one way to Mars,” Thomas said.

He said bringing back the crew is important because nobody knows the long-term health impacts of living on Mars. However, Thomas said an expedition to Mars is essential for the human race and called it the Holy Grail of human exploration.

“I think in the next century people will look back on this century the way we look back on the time of Magellan and Columbus.”

The baseline mission statement of the project says it is aimed at setting up a permanent human settlement on the Red Planet.

The project plans to send crew every two years from 2024 onwards. It started the global search for potential crew members in 2013 and drew a huge response. Thousands of people applied online from all over the world.

From a large pool of applicants, the number was cut down to 100 after a series of interviews. Very soon, 24 people will be sent for full-time training, reports The Australian.

“The large cut in candidates is an important step towards finding out who has the right stuff to go,” noted Bas Lansdorp, Co-founder & CEO of Mars One.

For the Mars One mission, seven Australians have been shortlisted.  They include a 19-year-old girl, named Teah. She has been described as a “country girl … fascinated by space and stars.”

Richards Josh, a 29-year-old engineer turned stand-up comedian is another Australian named for the mission.

“I see myself as a communicator, I have a background in physics, engineering, diverse in sciences generally – a jack of all trades. They want people who can do a little bit of everything,” said Richards in Brisbane.