A top official with France’s space agency has dismissed Elon Musk’s Mars exploration plans, questioning whether SpaceX will be able to find the money for the venture. Francis Rocard, head of the Solar System exploration program at CNES, said that the company is unlikely to find funding from NASA and it will be unable to finance the project itself.

In an interview with Courrier Sciences earlier this month, translated here, Rocard dismissed the BFR and its Raptor engines as “science fiction.” Rocard commended SpaceX for its Falcon 9 launch system offering cheap flights to NASA, but drew into question whether the space agency would fund a third party’s rocket while it’s also developing the Space Launch System. Teslarati noted on Thursday that CNES is providing a quarter of the $3.8 billion budget the ESA is spending on the Ariane 6 rocket, aimed at reducing costs to make spaceflight more affordable, a similar goal to SpaceX which aims for the BFR to be fully reusable to cut costs.

The BFR. Elon Musk/Twitter

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The BFR is a key part of the company’s plans for the future. Designed with full reusability in mind, SpaceX aims to conduct a number of ambitious trips with the BFR and enable a new era of multi-planetary civilization. Japanese billionaire Yusaku Maezawa is set to bring six to eight artists on a four to five day trip around the moon on the BFR in 2023, while SpaceX also plans to send six BFRs on a mission to Mars with the first humans setting foot on the red planet.

This doesn’t come cheap. Musk suggested at the Maezawa announcement earlier this month that the development cost is totaling around $5 billion. That’s far more than the $62 million in construction costs of a Falcon 9 rocket. Musk explained at the rocket’s unveiling at the International Astronautical Congress in Adelaide, Australia last September that the company is funding its development by planning to offer low-Earth orbit launches, including all new classes of satellite.

SpaceX is expected to start short hop tests at the firm’s Boca Chica facility in Texas starting next year. The plan is to complete a series of small jumps of a few hundred kilometers, before possibly completing high altitude flights the following year.

Perhaps science fiction is about to become reality after all.