The first time Raye Kass heard her brother cry was in 2003, when they spoke after the space shuttle Columbia disintegrated on its return to Earth, killing all seven crew members.

"He said: 'I can't believe they're gone," Raye Kass told, recalling a conversation with her brother James who was at NASA's Kennedy Space Center in Florida at the time, waiting for Columbia to land.

"When they were one minute late … he knew something had gone wrong," Raye said.

James had a personal connection to the shuttle crew, having worked closely with them in training for zero-gravity biology experiments.

"All seven of them I could say were friends of mine, which was unusual," James said. "So, I felt very, very discouraged."

Not so discouraged that he would abandon getting involved in such potentially perilous missions, however.

Now, the Kass siblings are acting as advisers to Mars One, a privately-funded mission that plans to dispatch four brave explorers on a one-way trip to establish a permanent colony on the Red Planet.

The pair will be heavily involved in the training and selection of the final 28 to 40 mission candidates. So far, the hopefuls have been narrowed down to 100 people, from an initial crush of more than 200,000 applicants.

Amid the clamor from critics who say the mission will never reach its destination, Mars One CEO Bas Lansdorp announced last month that the launch timeline will be pushed back two years, to 2026.

The setbacks don't faze Raye and James, however, as they already count themselves among those with doubts about the mission.

When invited to get involved with Mars One, Raye recalls, "I said to myself 'no way, it is a doomed enterprise with unfathomable obstacles to scale.'"

James added, "It seems a rather crazy venture to take people on a one-way mission."

After weighing the risks and rewards they eventually came around to the idea.

"I began to realize that the human condition, by its very nature, is to push through crisis, and we know that history was made when the impossible was made possible," said Raye.

While James says that there's "absolutely" no chance of a launch in the next 10 years, he believes it is better to contribute, than to stand on the sidelines.

"I had my very great doubts about the venture, but I thought if they want my advice, well I don't mind giving it … then I could at least help them," he said.

Between them they bring decades of experience to the table.

James, a nuclear physicist by trade, got his start working on Spacelab-1 in 1980, and has worked closely with astronauts on space shuttle, MIR, Skylab, Salyut and ISS missions.

Raye teaches group theory at the University of Concordia and has been involved in psychological training and experiments for the CAPSULS space simulation held in Canada, the SFINCCS experiment and several other NASA-related projects.

The siblings realised, in 1994, that their combined expertise could benefit astronaut training. That's when James told Raye to submit an application for the CAPSULS space simulation, which involved Canadian space pioneers such as Julie Payette and Dave Williams.

"He said: 'We'll work together, I know a lot about space missions … and you know a lot about psychology and teams … and I think we would make a great team,'" said Raye.

They are now looking forward to their roles in the selection and training of the final candidates for the Mars One mission, which will likely see trainees placed in a simulated Martian habitat for several months.

It is during this period that Raye says they will be able to pick up on the trainees' "soft skills," such as leadership and teamwork, that could prove critical to survival if something goes wrong on the journey.

The pair is also planning to provide "explicit" psychological and group dynamic training to the astronauts, something that James says has never been done before. He says that the Mars One crew will need to become "their own psychological experts" in order to deal with the intense feelings of isolation that come with being trapped in a tiny pod hundreds of millions of kilometres away from friends and family.

Not to mention the potential for technical calamity.

"The equipment has broken down, the backup equipment has broken down … and you know you have 30 days of oxygen before you're going to die ... do you go mad? do you kill you fellow man?" James said.

"This is where they will really have to some very good preparation, not only will the right people have to be selected obviously from the technical side, but from the psychological," he added.

Despite the risks and uncertainties, James and Raye want to be a part of the push to colonize the solar system.

"(We) feel we have a role, a mission, a search for excellence here -- that we can really contribute to what possibly will happen," Raye said.