(CNN) – SpaceX's Polaris Dawn mission launched early Tuesday morning, sending a crew of four civilian astronauts into orbit. Hours later, they have already made history: reaching the highest orbit around the Earth and breaking a record set during NASA's early days.
The company confirmed that the SpaceX Crew Dragon spacecraft carrying the crew reached its maximum altitude of 1,400.7 kilometers (872.7 miles) at 9:19 p.m. ET on Tuesday.
That distance surpassed the record set by NASA's Gemini 11 mission in 1966, which reached 1,373 kilometers during its trip around the Earth.
NASA's Apollo missions traveled farther but did not enter a traditional orbit around Earth. Their destination was the Moon, which is approximately 402,336 kilometers from our planet. The Polaris Dawn mission is also the farthest a human has traveled since the last Apollo mission in 1972, and the farthest a woman has traveled into space.
SpaceX and the Polaris Dawn crew may be celebrating their milestone, but the riskiest endeavors are yet to come on the five-day mission, which is designed to push the boundaries of commercial space travel and help test technologies SpaceX could use on deeper excursions into the cosmos.
As early as Thursday morning, the Polaris Dawn team — which includes mission funder Shift4 Payments CEO Jared Isaacman; his close friend and former U.S. Air Force pilot Scott “Kidd” Poteet; and SpaceX engineers Anna Menon and Sarah Gillis — will attempt the first commercial spacewalk.
This groundbreaking event, which will begin early in the crew's third day in space, is expected to take place while the crew is orbiting about 700 kilometers above Earth.
Isaacman, Menon, Poteet and Gillis will be exposed to the vacuum of space when their Crew Dragon capsule is depressurized and a circular hatch opens. And two crew members — Gillis and Isaacman — will exit the spacecraft during the roughly two hours the vehicle will remain with the hatch open in the vast expanse.
The crew will be protected from the relentless vacuum only by SpaceX’s new extravehicular activity (EVA) suits. The spacesuits were designed and developed in two and a half years, an incredibly fast time by aerospace standards.
By comparison, NASA has been trying to replace the International Space Station's aging spacesuits for more than a decade. Those suits were designed 40 years ago.
The Crew Dragon capsule is already putting the crew through a lengthy “pre-inspiration” process, which prepares astronauts’ bodies for the spacewalk. It works by slowly purging nitrogen from the crew members’ blood so that the gas doesn’t bubble up into their bloodstream as the pressure inside the vehicle changes.
The pre-breathing process is intended to prevent decompression sickness, the same dangerous and potentially fatal illness that divers can face if they try to surface too quickly.
The pre-inspiration protocol that the Polaris Dawn crew undergoes is completely different from that carried out on the International Space Station. The space station has special airlocks where astronauts can undergo a quick pre-inspiration process before beginning their spacewalks. It only lasts a couple of hours.
The Polaris Dawn crew's pre-breathing routine, however, will last about 45 hours, Gillis explained to CNN, as the oxygen content in the cabin slowly increases as the pressure decreases.
“What’s really cool about this (preinspiration) profile is that in many ways it’s much less risky than what’s typical on the space station,” Gillis told CNN. “It’s like opening a can of soda — and you want to open the can (and) have none of the bubbles come out because the pressure outside the can is the same as the pressure inside.”
By reducing the pressure inside Crew Dragon, Gillis explained, and putting on their spacesuits just when the ambient pressure is equal to the suit pressure, crew members can better mitigate any risk of unwanted bubbles.
The biggest challenge comes once the spacewalk is over: closing the hatch aboard the Crew Dragon capsule, getting pressurization back to normal and returning safely to Earth.
“They should be nervous about (this mission),” former NASA astronaut and SpaceX adviser Garrett Reisman told CNN in August. “Anytime you try something for the first time there are significant risks. I’ll feel a lot better when they’re back inside with the hatch closed and locked.”
