October 9, 2024
1 Solar System Way, Planet Earth, USA
Discovery

Polaris Dawn crew prepares for Thursday spacewalk – Spaceflight Now

Artist's impression of a Polaris Dawn astronaut floating outside the Crew Dragon capsule on the first commercial spacewalk. Graphic: SpaceX

Billionaire Jared Isaacman and SpaceX crew trainer Sarah Gillis prepared to open the forward hatch of their Polaris Dawn spacecraft early Thursday to take turns floating outside on the first non-governmental spacewalk in the history of space exploration.

With crewmates Anna Menon and Scott Poteet monitoring safety cables and umbilical cords inside the SpaceX Crew Dragon capsule, Isaacman and then Gillis plan to float out into open space after depressurizing the spacecraft around 2:23 a.m. EDT, using a scaffolding-like “Skywalker” assembly that extends just above the hatch for stability.

Even though their feet will be just outside the capsule, they won’t be able to “free float” away from the Crew Dragon. Their Space-X-designed pressure suits aren’t equipped with their own oxygen supply or other life-support equipment and rely on 12-foot-long umbilicals to supply air, power and communications.

As Isaacman and then Gillis float just outside the hatch, they will test the comfort and mobility of their pressured extravehicular activity, or EVA, suits by moving their arms, hands and legs through a series of positions to find out how much effort is required to perform basic tasks.

“We’re going to be using a number of mobility aids that the SpaceX team has designed, and it will feel like we’re dancing a little bit,” Isaacman said before launch. “The idea is to learn as much as we can about this suit and communicate that back to the engineers to inform future evolutions in the suit design.”

Cameras mounted inside and outside the Crew Dragon, along with others attached to the spacewalkers' suits, are expected to provide spectacular views of space and Earth below as the craft cruises through an elliptical orbit with a low point of 121 miles and a high point of 458 miles — 200 miles higher than the International Space Station.

The goal of the exercise is to perfect low-cost, easy-to-manufacture spacesuits for use by future civilian astronauts flying to the Moon or Mars aboard SpaceX's Super Heavy-Starship rockets.

“I think this journey of creating affordable EVA suits that can be scaled up to mass production is very valuable,” Isaacman said. “At some point in the future, there will be an armada of spacecraft coming to Mars, and those people will need to be able to get out of them and walk around and do important things.”

A SpaceX Falcon 9 rocket lifts off from Launch Complex 39A to begin the Polaris Dawn astronaut mission. Image: Adam Bernstein/Spaceflight Now

Isaacman, Poteet, Menon and Gillis blasted off Tuesday from Kennedy Space Center aboard a SpaceX Falcon 9 rocket. The crew accomplished the flight’s first major objective right away, ascending to an altitude of 870 miles — higher than any crewed spacecraft since the Apollo lunar program 60 years ago.

The highest point, or apogee, of the orbit was lowered to 458 miles for the spacewalk and the remainder of the five-day mission.

To prevent decompression sickness, or “bends,” as the crew transitioned from sea-level pressure to the reduced 5 psi pressure in their spacesuits and back again, flight controllers began a 45-hour process shortly after launch to increase cabin oxygen levels while slowly decreasing air pressure to help remove nitrogen from the crew's bloodstream.

“We don’t anticipate experiencing it (the curves), because a lot of preparation has gone into developing this pre-breathing protocol, which significantly reduces that risk,” said Menon, a former NASA biomedical flight controller. “But we are prepared if we need to.”

The Crew Dragon has no airlock and its life support system was not designed to support spacewalks. Necessary modifications included “adding a lot more oxygen to the spacecraft so we can supply oxygen to four suits via umbilicals throughout the spacewalk,” Gillis said.

“There have been improvements and expansions to the spacecraft’s environmental sensor suite to ensure that we have really good vision, both before, during and after exposure to vacuum. And… a completely new system, a nitrogen repression system” to increase cabin pressure back to normal after the spacewalk.

The Polaris Dawn crew looks up through the hatch of a Crew Dragon simulator, framed by a scaffolding known as the “Skywalker” that will provide hand and footholds during brief spacewalks by mission commander Jared Isaacman and Sarah Gillis. Gillis is visible at the bottom left of this photo and Isaacman at the top right. Their crewmates are Anna Menon, top left, and pilot Scott Poteet, bottom right. Image: SpaceX

Along with the Skywalker scaffolding, which extends just beyond the forward hatch, a motor drive system was added to assist with opening and closing the hatch and improved seals were fitted to ensure a watertight fit.

NASA astronaut Ed White conducted the first American spacewalk on June 3, 1965, floating free of his Gemini 4 capsule at the end of a long tether. Since then, NASA astronauts, Russian cosmonauts, Chinese taikonauts and astronauts from space station partner nations have conducted more than 470 government-sponsored spacewalks.

Isaacman said the iconic photos of White floating outside his Gemini capsule with Earth and space as a backdrop were inspiring, but he and Gillis ruled out the possibility of floating outside the Crew Dragon. And that's intentional.

“We’re not going to do the Ed White flight,” Isaacman told CBS News before the launch. “It may look cool, but it doesn’t help SpaceX learn a lot about (spacesuit) performance. It’s not very useful or helpful in understanding how you can work with a suit.”

To do so, he and Gillis will work through a “matrix” of planned movements to get a sense of how the suit's multiple joints move while pressurized, to test the performance of an innovative helmet-mounted heads-up display, to better understand how air-cooled suits deal with the extreme temperatures of space, and a variety of other factors.

The suit “includes all sorts of technology, including a heads-up display, a helmet-mounted camera, and a completely new architecture for joint mobility,” Gillis said. “There’s thermal insulation throughout the suit, including a copper indium tin oxide visor that provides thermal and solar protection.”

Plus, he said, “There are all kinds of redundancies, both in the oxygen supply to the suit and in all the valves and all the seals in the suit. It’s an incredible suit.”

Polaris Dawn crew (left to right): Anna Menon, pilot Scott “Kidd” Poteet, commander Jared Isaacman, and Sarah Gillis. Image: SpaceX

The heads-up display, which will project critical data onto the lower left side of the helmet's visor, is a feature that NASA's decades-old space station suits do not have.

“During the EVA, we will have information about our suit, the pressure, the temperature, the relative humidity, and also about the amount of oxygen we have used during the EVA. So there we have some key telemetry data. And it’s really cool that, in any lighting, you can still see it.”

The Polaris Dawn mission is the first of three planned by Isaacman, who owns and flies his own MiG-29 fighter jet, in cooperation with Musk. The second flight will be another Crew Dragon mission, while the third will be the first crewed flight of SpaceX's massive Super Heavy-Starship rocket, which is under development in Texas.

It's not known how much Isaacman is paying for the flights or how much SpaceX has funded on its own. Asked if he could share more details, Isaacman said “there's no chance.”

The mission, SpaceX's fifth commercial Crew Dragon flight into orbit and its 14th including NASA flights, is expected to last five days and end with a splashdown off the coast of Florida.

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