SpaceX launches first all-tourist crew into orbit

The crew has a 40-song Spotify playlist downloaded and queued up to play during their journey. It includes jams from a variety of artists, from Jain to KoЯn to Smashmouth.

Each passenger picked 10 songs for the list. There's a few space-related songs on it, including:

Here's what Sembroski said about the curated playlist:

SpaceX's five-hour launch window begins at 8:02 pm ET, and forecasters have give a 90% chance that the weather will be good enough for liftoff. If everything goes according to plan, this is what you should see.

When the countdown clock hits zero, the Falcon 9 rocket will fire up its engines and roar toward space.

About one minute later, the rocket will hit “Max Q,” an aerospace term that refers to the point during flight at which a vehicle experiences its maximum dynamic pressure.

Put simply: It’s when the rocket is moving at very high speed, at a time when the atmosphere is still pretty thick, putting a lot of pressure on the vehicle.  

Two and a half minutes after launch, the bottom part of the rocket, the largest section that gives the initial thrust at liftoff, will shut down its engines — at moment referred to as Main Engine Cutoff or MECO — and detach. That part of the rocket, with most of its fuel spent, will then head back down to Earth for a pinpoint landing on a seafaring platform so that SpaceX can refurbish and fly the rocket again (All part of the company's plan to save money and make spaceflight cheaper.)

Meanwhile, the second stage of the rocket, still attached to the crew capsule, will fire up its engine and continue accelerating faster and faster until it spends its fuel and reaches orbital velocities — or more than 17,000 miles per hour.

About 12 minutes post-liftoff, the second stage will detach from the crew capsule.

What's left of the rocket will be discarded in the ocean, while the Crew Dragon capsule and its four passengers will begin its three-day free-fly through orbit.

All the intense G-forces will be over, and the crew will be weightless. The tip of the capsule, called the nosecone, will open to reveal a large dome-shaped window. And the capsule will use its onboard thrusters to orient it into the correct orbit.

Any time a spacecraft leaves Earth there are risks, and there are no perfect measurements for predicting them.

But NASA estimates Crew Dragon has a 1-in-270 chance of catastrophic failure, based on one metric the space agency uses. For comparison, NASA's Space Shuttle missions in the 1980s to early 2000s ultimately logged a failure rate of about 1 in every 68 missions.

Because of the inherent risks of blasting a spacecraft more than 17,500 miles per hour — the speed that allows an object to enter Earth's orbit — Inspiration4 is theoretically more dangerous than the brief, up-and-down suborbital jaunts made by billionaires Jeff Bezos and Richard Branson.

Apart from the many perils of the launch itself — in which rockets essentially use controlled explosions more powerful than most wartime bombs to drum up enough speed to rip away from gravity — there's also the re-entry process. When returning from orbit, the Crew Dragon's external temperatures can reach up to 3,500 degrees Fahrenheit, and astronauts can experience 4.5 Gs of force pushing them into their seats, all while the ever-thickening atmosphere whips around the capsule.

During a Netflix documentary about the Inspiration4 mission, Musk described a capsule going through reentry as "like a blazing meteor coming in."

"And so it's hard not to get vaporized," he added.

After that, the Crew Dragon then has to deploy parachutes to slow its descent and make a safe splashdown in the ocean before rescue ships can whisk the four passengers back to dry land.

Despite the risks, a former NASA chief and career safety officials have said the Crew Dragon is likely the safest crewed space vehicle ever flown.

The hatch of the SpaceX Crew Dragon capsule has been closed in preparation for a launch as early as 8:02 p.m. ET. 

SpaceX is not seeing any problems with the spacecraft at this time and the weather continues to look good, according to a live stream provided by the company. 

The launch is the first to send tourists or otherwise non-astronauts into orbit.

The passengers will spend three days aboard their 13-foot-wide Crew Dragon capsule freeflying through orbit at a 350-mile altitude — 100 miles higher than where the International Space Station orbits. 

If all goes to plan, they’ll return to Earth by splashing down off the coast of Florida on Saturday. 

There are no official training requirements for a space tourism mission. Legally, if one chose to, they could just walk right up to the launch pad, strap in, and blast off without having any idea what to do at all once they got up there besides float around for a bit.

But the crew has spent the past six months taking on a training regimen with SpaceX, and they've also gone on a few bonding excursions to get comfortable with each other. (They will, after all, need to sleep, eat, use the bathroom and essentially become extremely close-quarter roommates during their three-day trip.)

So far, they've:

They've also studied the Crew Dragon manual forward and backward, used a special simulator to get their bearings in the capsule, and even done a 30-hour practice run.

"Throughout our training journey, it is front-loaded with a lot of academics. And then it moves into simulator work," Isaacman told CNN Business. "What you don't spend time training on is just the everyday normal stuff, like how are we going to take food out of the packaging without getting debris everywhere?"

For the record, the crew also practiced that too, for good measure.

The first all-civilian crew set to launch into orbit has arrived at Launch Pad 39A at Kennedy Space Center and is boarding their capsule. 

The launch window opens at 8:02 pm ET.  

This mission, dubbed Inspiration4, is the first orbital mission in the history of spaceflight to be staffed entirely by tourists or otherwise non-astronauts. 

The crew includes 38-year-old billionaire Jared Isaacman, who personally financed the trip, Hayley Arceneux, 29, a childhood cancer survivor and current St. Jude physician assistant, Sian Proctor, 51, a geologist and community college teacher with a PhD, and Chris Sembroski, a 42-year-old Lockheed Martin employee and lifelong space fan who claimed his seat through an online raffle.  

Inspiration4 — the first-ever orbital flight crewed entirely by tourists — is set to launch from NASA's Kennedy Space Center.

Here's who will be on board: