Very early this morning we watched as four private astronauts were exposed to the vacuum of space with two members actually exciting the Dragon capsule. Besides a handful of firsts, one of the main mission goals was to test these spacesuits in the actual environment and gather as much data as possible for teams at SpaceX.
This combined with the process of depressurizing the Dragon capsule among other milestones made for a successful and eventful EVA.
First Commercial Spacewalk
Normally when a Spacewalk happens on the ISS for example, crews use an airlock to isolate a small section of the station and depressurize it. This allows everyone else who isn’t participating to continue on per normal.
On the Dragon spacecraft, there is no airlock. Once the hatch is opened, the entireiety of the crew cabin is exposed to the vacuum of space. This means whoever is inside will need to be suited up and prepared. In order for the crew and SpaceX to be ready for hatch opening, they started preparing days in advance.
For example on the first day of the mission not long after lifting off, the crew began a two-day pre-breathe protocol. Here, Dragon’s pressure slowly lowers while oxygen levels inside the cabin increase, helping purge nitrogen from the crew’s bloodstreams. The point of this is to help lower the risk of decompression sickness during the spacewalk.
The next major steps began just hours before the spacewalk. Between the live stream and updates from SpaceX directly, they highlighted each of the necessary milestones leading up to the spacewalk. About an hour before opening the hatch, all four crew members were suited up inside their EVA spacesuits, which act almost like an individual spacecraft.
During this entire process, the crew had lines of communication between each other and teams at mission control helping direct and work through the process. Not long after suiting up, the secondary flow of oxygen was confirmed to be underway, which primarily provides cooling to the suits throughout the spacewalk.
With that complete, the suits were then switched to their primary flow path, which they use to fully pressurize ahead of suit leak checks. SpaceX then confirmed that the suit leak checks were complete and that the final pre-breathe was underway to help purge all remaining nitrogen from the crews’ bodies. At that point, Dragon’s cabin was at 8 psi as the pressure lowered ahead of the hatch opening.
At around 8 psi, they still needed to lower the pressure so they began venting from Dragon for around 10 minutes. 21 minutes into the EVA operation and the psi had gone down to 4. Eventually, Dragon’s cabin was below 1 psi and the spacecraft repositioned its trunk to face the sun ahead of the EVA.
Finally, the hatch was opened, marking the first time four humans were simultaneously exposed to the vacuum of space. Soon after Issacman was the first to exit the vehicle using what SpaceX calls skywalker, the additional bars for control and holding on to. Over the next 20 minutes, he conducted a few mobility tests before going back inside.
Next Sarah Gillis made her way outside the spacecraft. At 30 years old she now is the youngest human to complete a spacewalk. Similar to Issacman she also spent the time testing suit mobility and general operations.
SpaceX clarified that there were three main suit mobility tests meant to test overall hand-body control, vertical movement with Skywalker, and foot restraint. Specifically, they were quoted saying, “The first test focuses on using a single hand to control body movement. The spacewalkers will evaluate their ability to move in all directions, hold a single position for 10-15 seconds, and hold position while the other arm is simulating tool use.”
“The second test assesses the crew’s ability to move up and down using Skywalker. Issacman and Gillis will use both the horizontal and vertical bars and gauge their maximum reach.” And finally, “The third test evaluates using a foot restraint. Jared and Sarah will gauge difficulty in getting in and out of the restraint, how easily they can move their body, the ease with which they can maintain position while hands free or using tools, and recovery from a single foot disengaging” they said.
Eventually, after over an hour and a half of time spent on the EVA, the hatch was finally closed. From there, repressurization of Dragon was now underway. Teams raised the cabin pressure up to 8 psi, paused, let the atmosphere equalize, and then performed a cabin leak check prior to resuming repress all the way up to 14 psi. The entire process was estimated to take up to 50 minutes.
In another quote, they said, “Dragon uses pure nitrogen during repress, which mixes with the pure oxygen being released into the cabin via the open loop system that keeps the EVA suits pressurized. This process is unique to Dragon which acts as its own airlock. They then finally confirmed that Dragon’s cabin pressure was now 14.6 psi and the nitrox washout was complete.
Still More Mission
While the spacewalk was definitely the highlight of the mission, there are still a few more days before the eventual reentry and splashdown. There also are a handful of experiments that need to be completed. In reality, these began even before the EVA.
Yesterday for example on flight day 2, the crew conducted a series of activities on-orbit, including time dedicated to science and research. The crew focused on monitoring initial changes to eyesight and ocular health, studying how fluid shifts and exposure to microgravity affect blood flow, and assessed how medications are processed by the body while on-orbit.
Tomorrow on the fourth day, they plan to complete a Starlink demonstration. Specifically, the Polaris Dawn crew has mentioned transmitting a message down to Earth using SpaceX’s constellation of internet satellites. They will be the first crew to test Starlink laser-based communications in space, which SpaceX believes will provide valuable data for future space communications systems.
On Day 5, the crew will be busy preparing for the journey back home and eventual landing. This leads to day 6 when they are set to return to Earth. That will include deorbit burns, Earth reentry, and eventually a splashdown off the coast of Florida. The mission did experience quite a few weather delays leading up to the launch but they eventually found a clearing for both the launch and landing timeframe. Over the next few days, we should expect more updates from the crew as they get closer to this final mission milestone.
With the EVA complete, SpaceX now has much more information on the performance of their new suits. While it seems they performed very well, the company will now likely talk to the crew and figure out what areas they like and what changes they could make. The company will definitely be upgrading this technology over time to make it even more comfortable and usable. EVA spacesuits are complex and the nature of their design limits mobility among other general motor functions. The more data and experience the company gets, the more fine-tuned the design will get as well.
At the end of the day, these suits were upgraded from the current intravehicular (IVA) suit. In a statement, the company said, “Evolved from the IVA suit, the EVA suit looks similar but provides greater mobility, a state-of-the-art helmet heads-up display (HUD) and camera, new thermal management textiles, and materials borrowed from Falcon’s interstage and Dragon’s trunk.” SpaceX points out that all of these enhancements to the EVA suit are part of a scalable design, allowing teams to produce and scale to different body types as SpaceX seeks to create greater accessibility to space for all of humanity.
Before the launch, the crew worked with the suits and SpaceX to get a better understanding of how the spacesuit performs in a vacuum, gather a collection of spacesuit and biometric data to assess the overall system’s performance in a flight-like environment, and even insight into the various thermal states expected throughout the spacewalk, among others.
SpaceX is quoted saying, “Building a base on the Moon and a city on Mars will require millions of spacesuits. The development of this suit and the execution of the spacewalk will be important steps toward a scalable design for spacesuits on future long-duration missions as life becomes multi-planetary.”
It’s clear they have some ambitious plans for the future. Only a few days ago Musk tweeted saying, “The first Starships to Mars will launch in 2 years when the next Earth-Mars transfer window opens. These will be uncrewed to test the reliability of landing intact on Mars. If those landings go well, then the first crewed flights to Mars will be in 4 years. Flight rate will grow exponentially from there, with the goal of building a self-sustaining city in about 20 years. Being multiplanetary will vastly increase the probable lifespan of consciousness, as we will no longer have all our eggs, literally and metabolically, on one planet.”
While Musk is known to have some ambitious timeline estimates that should be taken with a grain of salt, it’s clear what the company is aiming for. They believe these suits and the first commercial spacewalk are some of the first steps toward this future.
Conclusion
Early this morning on Flight Day 3, the four crew members of the Polaris Dawn mission were exposed to the vacuum of space after opening the hatch. Here Issacman and Gillis made their way outside the vehicle separately to conduct a handful of tests. In the future, we can likely expect more missions like these as SpaceX works to continue upgrading this technology.