WASHINGTON — A private astronaut mission that will feature the first spacewalk from a Crew Dragon spacecraft has suffered another delay, this time to at least the middle of this year.

The Polaris Program, a series of private astronaut missions backed by billionaire Jared Isaacman, announced Feb. 8 that its Polaris Dawn mission was now scheduled for no earlier than the summer. The program had previously announced an April launch date.

“The additional time continues to provide necessary developmental time to ensure both the completion of these mission goals and a safe launch and return of Dragon and the crew,” it posted on social media.

Those goals are highlighted by a spacewalk, the first from a Crew Dragon spacecraft. That requires both the development of an extravehicular activity (EVA) spacesuit that can be used outside the spacecraft as well as modifications to the Crew Dragon, which lacks an airlock, to allow its cabin to be depressurized before the spacewalk and then repressurized after the spacewalk.

Isaacman had previously stated that work was more difficult than expected, contributing to the delays. “Very solid @PolarisProgram training week. In addition to the sims, we spent a lot of time pressurized in the EVA suits working contingencies. Lots to get done, but it feels like momentum is building,” he posted Jan. 26.

According to industry sources, SpaceX significantly underestimated the work converting the pressure suit currently worn by astronauts inside Crew Dragon into an EVA suit. When SpaceX and the Polaris Program announced the Polaris Dawn mission two years ago, they projected a launch as early as the fourth quarter of 2022.

SpaceX Chief Executive Elon Musk, in a presentation to company employees posted online Jan. 12, hinted at the difficulties in spacesuit development. “We’ve got to redesign the suit so that you actually move around in it,” he said. “It’s quite hard to still be mobile in an inflated suit.”

The company is using the Polaris Dawn mission to test the suit that the company plans for future missions. “This is going to be a significant milestone,” he said. “Having a high-mobility spacesuit that isn’t crazy expensive, ideally, and that you can walk around in comfortably is a great deal. It’s actually an important thing that needs to be developed and ultimately made in large numbers.”

Neither SpaceX nor the Polaris Program have released images of the suits, although Isaacman described them as “heavier and bulkier” than the current Dragon pressure suits. All four members of the crew will wear the suits, including those who remain inside Dragon, with the suits taking the place of the pressure suits worn during launch and reentry.

Besides the spacewalk, the mission will test intersatellite communications using optical links between the Crew Dragon spacecraft and Starlink satellites. The mission, lasting up to five days, will also conduct health research, including studies of the radiation environment at altitudes as high as 1,400 kilometers, higher than any crewed mission since the Apollo 17 mission to the moon in 1972.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...