In the early morning hours on Tuesday, four commercial astronauts soared into the sky from Cape Canaveral, Fla., on a SpaceX Falcon 9 rocket, embarking on a historic mission.
The four astronauts — Jared Isaacman, Kidd Poteet, Sarah Gillis and Anna Menon — will spend five days in a SpaceX Crew Dragon capsule orbiting Earth. But they aren’t up there for a pleasure cruise: they’ll be hard at work doing various tests and experiments.
One of the most ambitious of these tests is the first commercial spacewalk — or extravehicular activity (EVA) — using SpaceX’s newly designed spacesuits, scheduled for 2:23 a.m. ET Thursday. There is a second opportunity Friday at the same time, should the spacewalk be delayed for some reason.
Spacewalks are dangerous endeavours for professional astronauts, let alone civilians.
“EVA is a risky adventure, but again, we’ve done all the preparation: we did the capsule testing, we did the suit testing, we did the hyperbaric chambers, we did all the work to really get ready for this,” said Bill Gerstenmaier, an engineer at SpaceX who was head of NASA’s human spaceflight until 2020. “We kind of built off of what NASA’s heritage was.”
But the spacewalk won’t be one we’re used to seeing.
A history of spacewalks
On March 18, 1965, Soviet astronaut Alexei Leonov ventured out of his Voskhod-2 capsule and conducted the first spacewalk. But it didn’t exactly go as planned.
After floating in space for about 10 minutes, Leonov made his way back to the capsule, which had an inflatable air lock. However, he soon realized that his spacesuit had become stiff and puffy; he couldn’t fit through the door. The only thing he could do to reduce the air in his spacesuit was to let some bleed out, a little at a time, though that presented the danger of potential oxygen starvation.
He didn’t let the officials back on the ground know what he was doing, but managed to pull it off and return to the safety of his capsule.
WATCH | Aleksei Leonov’s first spacewalk:
The first American spacewalk, on June 3, 1965, was a little different. Ed White would be the astronaut making the attempt. Instead of an airlock, however, the entire Gemini IV capsule had to be depressurized, exposing White and fellow astronaut James McDivitt to the vacuum of space.
Today, astronauts on the International Space Station (ISS) wear a bulky spacesuit that has a self-contained life support unit, which allows them to move around the exterior of the 109-metre-long laboratory. To avoid floating off into space, they are tethered to the various rails around the station.
The Polaris Dawn crew will be taking a page out of White’s Gemini IV spacewalk. The entire capsule will be depressurized and all four astronauts will be exposed to the vacuum of space. Isaacman and Gillis will then conduct the anticipated 15- to 20-minute spacewalk while attached to a short tether.
Under pressure
Of course, space is dangerous. It’s not so much that it’s trying to kill us, but more that our bodies were built for Earth and Earth alone, which is why venturing out into the vacuum of space is so challenging.
For example, the normal air we breathe is 78 per cent nitrogen and 21 per cent oxygen (with one per cent other gases). Astronauts in spacesuits can’t breathe this way for a couple of reasons: one is a risk of low oxygen and two being that it would be difficult to move around due to the pressure differences between their suit and the vacuum of space.
Instead, they breathe pure oxygen, which also helps them avoid depressurization sickness.
“When we do our spacewalks on the International Space Station, we do a pre-breathe to reduce the amount of nitrogen in our body,” said retired Canadian astronaut Dave Williams, who not only is a doctor himself but holds the record for most Canadian spacewalks, with a total of 17 hours and 43 minutes.
“In some cases, that can take place overnight. In other cases, it can take place over the course of a couple of hours. But the crew of Polaris Dawn, all four crew members are going to have to go through the same pre-breathe preparation, because the entire spacecraft will be taken to vacuum.”
The Polaris Dawn pre-breathe begins on the day they reach space and continues until the hatch is open on the third day of flight for the spacewalk.
While this is a test, it’s not as though the spacesuits haven’t undergone rigorous testing down here on Earth.
“[They] have been doing a lot of testing over several years … minimizing the risk of bubbles forming in the bloodstream, which is what happens to folks who go diving pretty deep and then decide to go up pretty fast — what the divers call the bends,” said Emmanuel Urquieta, vice-chair of aerospace medicine and associate professor of medicine at the University of Central Florida.
Decompression sickness, or venous gas emboli (VGE), refers to bubbles that can form in the bloodstream in astronauts conducting a spacewalk for the same reason that divers are at risk. The spacecraft is pressurized to sea level, or roughly 14.7 pounds per square inch absolute (psia), which is absolute zero pressure that occurs in a perfect vacuum. During a spacewalk, their spacesuits are pressurized far lower than that, with NASA astronauts pressurized at 4.3 psia.
But what happens if the Polaris Dawn astronauts do get decompression sickness?
Urquieta said if someone diving experienced a mild case of decompression sickness — say, pains in the joints — the diver would be taken to a hyperbaric chamber, which would gradually increase the pressure and then gradually decrease it back to sea level. Theoretically, this could also be done on the SpaceX Crew Dragon, where they close the hatch and perform the same task.
“So even if that was the worst-case scenario, there is a possibility to treat that case in space,” he said. “Again, all these things have been thought [about] over the years and historically, with other vehicles.”
Both Urquieta and Williams are confident the spacesuit testing will be successful, and that this suit is just the first iteration of different suits to come, eventually likely leading to the NASA spacesuit with its own life support system.
For Williams, once an astronaut, always an astronaut: he’s offering his help.
“If anybody wants to give me a call,” he said. “I’m more than happy to go and evaluate all sorts of suits.”
