After several delays, the privately-operated Polaris Dawn mission has launched aboard a SpaceX rocket — putting four astronauts in the path of history.

Polaris Dawn is poised to be the first non-government mission to perform a spacewalk. But not only that — it'll do that about 700 kilometers (435 miles) above Earth. The highest ever.

To compare: the International Space Station (ISS) orbits Earth at about 400 kilometers, where the radiation is less intense.

It will also orbit Earth through regions of a highly-charged belt of radiation. There are two of these "Van Allen Belts", an inner and an outer one.

Astronauts tend to avoid the hazardous Van Allen Belts, but they have to travel through them toreach the moon and Mars.

The four astronauts on the Polaris Dawn mission will test new spacesuits, designed by Elon Musk's company, SpaceX, to see how well they protect them against the Van Allen Belt radiation.

SpaceX is also providing the spacecraft — a Falcon 9 rocket and Dragon capsule for the crew — to reach an altitude beyond the current record of 1,373 kilometers, set by NASA's Gemini 11 mission in 1966.

Who is the Polaris Dawn crew?

• Jared Isaacman, Mission Commander
• Scott Poteet, Mission Pilot
• Sarah Gillis, Mission Specialist
• Anna Menon, Mission Specialist and Medical Officer

Polaris Dawn, the first of a three-part program, is Isaacman's idea.

Isaacman is a billionaire entrepreneur, who made his money in digital payments and military defense. He previously financed and flew on SpaceX's Inspiration4 mission, the first civilian mission to orbit Earth.

Why are the Van Allen Belts dangerous for humans?

The Van Allen Belts consist of charged particles locked in place by Earth's magnetosphere, which includes its magnetic field.

Earth's magnetosphere traps high-energy radiation particles and protects our planet from solar storms and other threats to daily life from space.

While the outer belt holds high-energy particles from the sun, the inner belt is formed by cosmic rays that interact with Earth's atmosphere.

They were discovered by American physicist James Van Allen in 1958.

The Van Allen Belts range from about 680 kilometers above Earth's surface to what some estimates suggest is about 40,000 kilometers from the surface of the planet. And there's a gap between the first and second belt.

The inner "proton" zone is centered at about 3,000 kilometers from Earth's surface and the outer "electron" zone is centered about 15-20,000 kilometers from Earth's surface.

The Polaris Dawn spacewalk will expose the crew to higher levels of radiation than on the ISS. They hope to collect data on the effects of that radiation as a key scientific experiment.

In 2025, NASA plans to send astronauts beyond the Van Allen Belts to land on the south pole of the moon, and eventually on to Mars. Any data provided by Polaris Dawn will feed into those future missions.

Planned health research on Polaris Dawn

Polaris intends to use data from the mission to create research Biobanks to study the effects of space travel on human biology.

It will investigate the effects of space travel on eyesight and brain structure — a major health risk in space, known as Spaceflight Associated Neuro-ocular Syndrome (SANS).

The team also hopes to contribute to studies into decompression sickness (DCS), another health risk during spaceflight. DCS occurs when nitrogen gas bubbles (or gas emboli) damage human tissue.

First test of laser communications in space

The crew will test laser communications provided by SpaceX's Starlink satellite network. Starlink is large satellite constellation, eventually consisting of about 12,000 satellites for communication on Earth and in space. It was used early in the Russia-Ukraine war.

Polaris hopes its communications tests will provide "valuable data for future space communications systems necessary for missions to the Moon, Mars and beyond."

What's planned for future Polaris missions?

Isaacman has committed to three missions in collaboration with SpaceX. This first mission is scheduled to last five days.

The second mission will, they say, "expand the boundaries of future human spaceflight missions, in-space communications, and scientific research."

And the third mission will be the first crewed test of SpaceX's reusable Starship spacecraft.

As with any space mission, the Polaris Dawn launch on August 26, 2024, may be delayed due to extreme weather conditions or technical issues.

Edited by: Zulfikar Abbany

This article was originally published August 23, 2024, and updated with developments August 26, 27 and 28, and September 11, 2024.

Sources:

Polaris Dawn: About the mission https://polarisprogram.com/dawn/

What are the Van Allen Belts and why do they matter? (NASA) https://science.nasa.gov/biological-physical/stories/van-allen-belts/