Let's hope the spacesuits hold up for extravehicular activity
The Polaris Dawn mission to send humans to a 1,400 km orbit - higher than 1966's Gemini 11 - is set for launch in less than a week.
The private mission led by Shift4 CEO Jared Isaacman represents the furthest humans have ventured from Earth since the days of the Apollo program. The plan is to launch Isaacman and his three fellow astronauts in a Crew Dragon spacecraft to a 190 x 1,200 km orbit. The Dragon's Draco thrusters will then raise the orbit to 190 x 1,400 km, surpassing that of Gemini 11, before the orbit is lowered to 190 x 700 km for the first commercial spacewalk.
The mission is expected to last five days, and if all goes according to plan, it will take place as NASA finally decides what to do with Boeing's Starliner and whether its crew should also join the ranks of SpaceX astronauts.
The objectives for the mission are to grab that Earth-Orbit altitude record for humans, then perform a commercial spacewalk with SpaceX-designed Extravehicular Activity (EVA) spacesuits, perform a first test of laser-based Starlink communications on a human spaceflight, and finally undertake several experiments for partner institutions.
The trip carries risks. At 1,400 km up, the spacecraft and its occupants will be exposed to a higher radiation environment than the International Space Station (ISS).
While the orbit will be lowered to 190 x 700 km for the spacewalk, exiting the capsule is inherently dangerous, not least because this will be the first time the SpaceX EVA suit has been used in this environment, but also because since the Crew Dragon does not have an airlock, the cabin will need to be depressurized before the spacewalkers can venture outside.
SpaceX's EVA spacesuit is an evolution from the Intravehicular Activity (IVA) suit, with good mobility and new thermal management textiles and materials that have seen action on the Falcon interstage and Dragon's trunk.
The trunk of the Dragon spacecraft has proved surprisingly - and inconveniently for those on the ground - durable. A large chunk that survived reentry was found in Australia two years ago, and other bits and pieces have made it back to Earth intact in the months since. In a July briefing, SpaceX said it would be moving Dragon recovery back to the US West Coast and have Dragon jettison its trunk after the de-orbit burn takes place.
Isaacman said that Polaris Dawn would be the first of three Polaris missions. Polaris II will build upon the lessons of Polaris Dawn, and Polaris III will be the first human spaceflight using SpaceX's Starship.
Isaacman said Starship "could very well be the 737 for human spaceflight someday, but it'll certainly be the vehicle that will return humans to the Moon." ®