Mars One has delayed its launch plans by two years — again. In a video released by the Dutch nonprofit March 19, CEO Bas Lansdorp said that delays in raising funding forced them to push back robotic missions scheduled for 2018 until 2020, with later missions, including one-way human expeditions there, also postponed. Last month, Lockheed Martin and SSTL said they had not done any work on those robotic missions after completing study contracts last year.

“Going to Mars is very difficult. For example, NASA has been talking about going to Mars in 20 years for more than 45 years now,” he said.

Lansdorp also used the video to push back against some of the recent criticism of the venture.

The video was posted to YouTube three days after Medium published an interview with a Mars One finalists who alleges Landsdorp’s venture is “ripping off” its supporters. Joseph Roche, a physics professor and one of 100 finalists for Mars One, said candidates received “points” during the selection process if they donated money to Mars One or purchased merchandise. An interview as part of the selection process was simply a ten-minute Skype call, he said.

“That means all the info they have collected on me is a crap video I made, an application form that I filled out with mostly one-word answers… and then a 10-minute Skype interview,” Roche said. “That is just not enough info to make a judgment on someone about anything.”