SpaceX is getting ready to set out on its historic Polaris Dawn mission, which will send four astronauts into orbit aboard its Crew Dragon capsule. The five-day journey through the Van Allen radiation belts will include the first spacewalk done by private astronauts.

If you’re curious about the mission, here’s what you should know and how to watch it live.

What is the Polaris Dawn mission?

First announced in 2022, Polaris Dawn is a mission funded by billionaire and private astronaut Jared Isaacman. In addition to Isaacman, three other privately trained astronauts will embark on the mission, including retired US Air Force fighter pilot Scott Poteet, as well as SpaceX engineers Anna Menon and Sarah Gillis. Only Isaacman and Gillis will perform the spacewalk, which will take place around 430 miles above Earth.

Once launched into orbit, the four crew members will eventually reach a maximum altitude of around 870 miles, making it the furthest astronauts have traveled since the Apollo missions more than 50 years ago. They’ll also fly through the Van Allen belts, two bands of radiation NASA says consist of high-energy particles that come from the Sun and the atmosphere’s interaction with cosmic rays.

Why is Polaris Dawn so important?

The spacewalk isn’t the only objective of the Polaris Dawn mission. The astronauts will also test SpaceX’s extravehicular activity (EVA) spacesuits, which are made with new materials for improved mobility. These suits are paired with a 3D-printed helmet with a heads-up display and a visor designed to mitigate glare.

All four astronauts will wear the upgraded suits when the spacewalk takes place, as the Crew Dragon doesn’t have an airlock, leaving the crew members inside the capsule “exposed to the vacuum of space,” according to SpaceX. During the spacewalk, Isaacman and Gillis will perform tests with the new spacesuits.

Since the capsule will pass through the Van Allen radiation belts, the mission will also contribute to research about the effects of space radiation on the human body. Additionally, the Polaris Dawn crew will test Starlink’s satellite internet technology to communicate with Earth, as well as conduct research on decompression sickness and Spaceflight Associated Neuro-Ocular Syndrome.

When is Polaris Dawn?

Polaris Dawn was scheduled for a launch attempt on Tuesday, August 27th, but that was scrubbed as teams took “a closer look at a ground-side helium leak on the Quick Disconnect umbilical, according to @SpaceX. After another delay, a failure of a Falcon 9 rocket’s attempt to land caused the FAA to ground the rocket temporarily, putting the Polaris Dawn launch on hold for now.

The Crew Dragon capsule will launch aboard SpaceX’s Falcon 9 rocket from NASA’s Kennedy Space Center in Cape Canaveral, Florida.

How to watch the Polaris Dawn launch

You can watch a livestream of the mission from SpaceX’s website and its X page. Coverage will begin at around 12:05AM ET.

The spacewalk, which will take place on the third day of the mission, will also be livestreamed. It will likely be available from SpaceX’s website and on X.

Update, August 29th: Added details of the launch delay due to the Falcon 9 rocket grounding.