When SpaceX presented its intervehicular suit for the Crew Dragon spacecraft in September 2017, it made an impression due to the futuristic design. Although on the inside it was not substantially different from other intravehicular suits (IVA) intended to protect the crew against possible depressurization of the vehicle or the presence of smoke and toxic gases, the external appearance of the suit was a turning point in “fashion.” space”. Now, after more than two years of development, SpaceX has presented the extravehicular version (EVA) of the suit, intended to be used for the first time on the Polaris Dawn mission, funded by billionaire Jared Isaacman, in which the first commercial spacewalk in history. And the result? Well, the most surprising thing is that there are few surprises. In other words, it is very similar to the IVA suit.
And why is this surprising? Well, because although both types of suits are designed with a vacuum in mind, the EVA suit must offer greater mobility and a more complex temperature control system, in addition to guaranteeing a continuous oxygen supply in case of emergency. Of course, an EVA diving suit can also function as an IVA suit (but not the other way around). This is what happened in the Gemini, Apollo and Skylab missions, which used a pure oxygen atmosphere. For example, the A7L and A7LB suits of the Apollo were used for IVA and EVA, although with differences: to use it in the extravehicular version, the IVA gloves were replaced with more resistant ones and a protective cover and a visor for the helmet were added, lunar boots (only for walks on the lunar surface) and of course a PLSS backpack with life support (plus emergency oxygen supply on the backpack). In addition, the astronauts had to wear a jumpsuit with water tubes for cooling during extravehicular walks, an unnecessary piece in the IVA version.
So why is it striking that SpaceX’s EVA suit looks like the IVA? Well, on the one hand, because the SpaceX diving suit seems not too bulky to be able to incorporate all the layers of insulating material necessary to protect an astronaut outside his ship and, at the same time, flexible enough to allow him to move effectively (a spacesuit in a vacuum it is basically a pressurized balloon with a human being inside who must exert significant force to move the limbs; for example, it is not uncommon for astronauts to end up with purple fingertips and wounds under their nails after hours of fighting against the gloves of your diving suit while trying to manipulate objects). As we mentioned, the Apollo suits were EVA and IVA, but in their IVA version they were still relatively bulky. On the other hand, the similarity of the new EVA suit to the IVA is striking because the atmosphere of the Crew Dragon is nitrogen and oxygen, as on Earth and in the rest of current spacecraft. Indeed, the Gemini and Apollo could use the same IVA suit for space walks thanks to the fact that the atmosphere they used in space was pure oxygen, but if you need a decompression procedure, using the same type of suit is neither so trivial nor so So comfortable.
In the Polaris Dawn mission, Jared Isaacman, Scott Poteet, Sarah Gillis and Anna Menon will fly aboard the Crew Dragon Resilience in the second solo mission of the SpaceX manned spacecraft and will be placed in an elliptical orbit with an apogee of 1,400 kilometers , the highest for a manned mission in history (leaving aside the Apollo missions). They will then descend to an orbit of 700 kilometers, where they will carry out the spacewalk. The extravehicular activity will last approximately an hour and a half—two hours including depressurization—and during it Jared Isaacman and Sarah Gillis will open the front hatch of the ship and take turns exiting outside without, apparently, removing their bodies completely from the capsule. . During the walk, the astronauts will lean on a metal structure called Skywalker, designed taking into account that it must support the exhaust from the front Draco engines. The astronauts will be connected to the ship by an umbilical similar to the one currently used in the IVA suits, which connects to the right thigh, although in the EVA version it will have controls to regulate the conditions of the suit, including a temperature control. Surprisingly, they will not carry an emergency oxygen supply system (this is possible because they will not go far, but for later versions of the suit this essential system will have to be added; in any case it is expected that an emergency connection will be available for another umbilical in case things go wrong).
When SpaceX showed last January a render simulating the Polaris Dawn spacewalk, the similarity of the EVA suit to the IVA suit was striking. Although many thought it was artistic license, in the end the external differences are minimal. Obviously the EVA suit appears reinforced in certain areas and now includes a gold visor to protect the crew from solar radiation (the gold tint is mainly due to a layer of copper, not gold, as well as indium tin oxide) . The visor, apart from its golden color, includes a HUD that will project information to the astronaut about the status of the suit (amount of oxygen, humidity, temperature, etc.). The helmets will also have a built-in camera. The EVA suits feature new “spiral zippers” to make putting them on and taking them off easier. The boots are made from the same material used in the interstage section of the Falcon 9 and the trunk of the Crew Dragon. Logically, the gloves of the EVA suit have been reinforced compared to the IVA version (their exterior is white, while those of the IVA suit are black). The use of clothing with cooling tubes or the precise internal pressure (the higher the pressure, the stiffer the suit) has not been discussed.
During the press conference given by the Polaris Dawn crew on May 4 in which the design of the EVA suit was revealed, the procedure for the spacewalk was also announced and is critical to understanding the similarity between the two suits. Since there is no airlock on the Polaris Dawn mission, the method of purging nitrogen from the blood is different from what we know on the International Space Station or the Chinese Space Station, where the crew breathes pure oxygen for hours, at rest or exercising. , before putting on the suits, which have an atmosphere of pure oxygen. In the case of Polaris Dawn, the Crew Dragon will first reduce its total internal pressure progressively over days while increasing the percentage of oxygen in the atmosphere, but without reaching a 100% oxygen atmosphere as in the Gemini or Apollo. By starting from a relatively low percentage of nitrogen (which has not been specified), astronauts will be able to purge the remaining nitrogen from their blood during the capsule depressurization period by breathing pure oxygen in their suits.
Taking advantage of the presentation of the suit, Elon Musk published a couple of messages on X indicating that SpaceX’s future suit will be even better and that the company’s next EVA suit will include a powered backpack to facilitate mobility. Musk’s comments are striking because, remember, at the moment there is no need for these suits: the EMU and Orlán suits continue to be used on the ISS and the Axiom company suits will be used in the Artemis program. The only missions that could take advantage of them are commercial solo flights by Crew Dragon, commercial space stations, or future Starship missions other than those related to the Artemis program. Naturally, it could also be that Musk was taking the opportunity to suggest that NASA opt for his suits for the Artemis HLS and forget about the Axiom ones. Be that as it may, soon the SpaceX EVA suit will be the fourth extravehicular spacesuit in service along with the EMU, Orlán and Feitian. And, of all of them, it will be the least voluminous. However, we will have to wait to see a fully autonomous version with a life support backpack to appreciate the differences with other current diving suits.
