The Polaris Dawn spacecraft will be unlike any other Dragon spacecraft that has flown before.
The SpaceX Crew Dragon capsule for the Polaris Dawn mission has modifications for the first-ever private spacewalk, which will take place after the scheduled launch on August 27. The Polaris Dawn Dragon will also fly higher than any crewed spacecraft since the Apollo missions, soaring about 435 miles (700 kilometers) above Earth.
Read below about the changes to the Dragon Polaris Dawn spacecraft, which will carry four astronauts into orbit: billionaire financier and commander Jared Isaacman, who also flew, funded and commanded the Inspiration4 mission in September 2021; pilot Scott “Kid” Poteet, a retired U.S. Air Force lieutenant colonel; and mission specialists Sarah Gillis and Anna Menon, both SpaceX engineers.
Related to: SpaceX Polaris Dawn Crew Lands at Launch Site Ahead of First-Ever Private Spacewalk (Photos, Video)
Dragon hatching and life support
The Polaris Dawn spacewalk will involve opening the Dragon hatch, which contains a new engine to do the job — but the capsule will not have an airlock. That’s different from spacewalks on the International Space Station and NASA’s retired space shuttle, where the airlock allowed the rest of the spacecraft to be isolated from the vacuum of space.
The lack of an air chamber in the Dragon means that all four astronauts in Polaris Dawn will wear their spacesuits during the spacewalk. The astronauts also cannot purge nitrogen from their bodies and avoid decompression sickness using pre-breathing procedures as they do on the International Space Station. Instead, the spacecraft will gradually lower its overall internal pressure while the partial pressure of oxygen rises, which will remove the nitrogen. The four astronauts will then use pure oxygen in their suits during the spacewalk.
“We start at about 14.5 psi and go down to about 8.65 as the final stage of our pre-breathing, over a long period of time, to slowly pull nitrogen out of our bodies and reduce the risk of decompression sickness,” Gillis explained at a news conference on Monday (Aug. 19).
Equipped with Starlink
Polaris Dawn will also feature a new communications system using laser links provided by SpaceX’s Starlink broadband satellites, Isaacman explained at the press conference. “There’s a laser in the trunk of the vehicle that we’re going to fly that will communicate with other Starlink satellites through beams of light,” he said. “That’s pretty cool.”
Laser communications will be difficult, Isaacman said, because it will involve the Dragon spacecraft and the Starlink spacecraft moving independently of each other at 17,500 mph (about 28,200 km/h), sending information from one spacecraft to Earth and then to the other spacecraft.
“It’s an opportunity to open up a whole new communications path, not just for Dragon, but for Starship or other satellites or telescopes out there,” Isaacman said. (SpaceX’s Starship is a next-generation spacecraft for heavy missions, especially interplanetary missions.)
Isaacman suggested that Starlink could at some point take over some of the communications duties for missions that typically use the U.S. satellite tracking and data transmission system, which is used by astronauts on the International Space Station and the U.S. military.
spacewalk suits
The new suit developed by SpaceX for spacewalks or extravehicular activities includes several changes that make it suitable for the vacuum of space. SpaceX previously said the new thermal management system, to keep astronauts’ temperatures stable, includes materials used in the Dragon chest and SpaceX’s Falcon 9 rocket intermediate stage.
The visor has been coated with a layer of copper to protect against radiation, using a similar tin oxide to that used in the wraparound dome window that flew on Inspiration4. Additionally, displays and cameras inside the helmet allow information to be displayed before the astronauts’ eyes. Other changes include more flexible suit joints, an umbilical cord for life support and a new cooling knob to regulate internal temperature.
“There’s all sorts of redundancy throughout the suit, whether it’s in the oxygen supply to the suit, or all the valves and all the seals that go through the suit. It’s an amazing suit,” Gillis said at the press conference.
Mobility Aids
Since spacewalks involve moving in a frictionless environment, SpaceX has developed mobility aids to allow astronauts to move safely. Gillis said a “new structure” is available to grab onto outside the Dragon’s nose hatch.
In addition, there are hand and foot positions inside and outside the spacecraft for astronauts in spacesuits. “We won’t just be moving around the spacecraft,” Isaacman said.
He noted that the Gemini spacewalks of the 1960s allowed NASA astronauts to learn proper spacewalk procedures. After testing devices such as the Handheld Maneuvering Unit, NASA quickly realized that astronauts were vulnerable to overheating without spacecraft controls. In consultation with ground crews, astronaut Buzz Aldrin (who later landed on the moon with Apollo 11) demonstrated the effective use of these tools during his spacewalk aboard Gemini 12 in November 1966.
“Be very deliberate in your movements,” Isaacman said of what NASA learned. “You want to make good use of your mobility aids. In fact, a lot of that pioneering work by Buzz Aldrin paved the way for many future spaceflights to succeed.”
