Blue Origin's maiden crewed flight on Tuesday involves four people who will cross the Karman line, which separates Earth's atmosphere from space, for the very first time.

Here is a brief look at the quartet of soon-to-be astronauts.

The tycoon, Jeff Bezos

Jeff Bezos, 57, will leave behind the planet where he made his vast fortune for a few minutes on a spaceship built by the company he founded in 2000, when he was still merely a single-digit billionaire.

Thrill-seekers might soon be able to get their adrenaline kicks—and envy-inducing Instagram snaps—from the final frontier, as space tourism finally lifts off.

All you'll need is a bit of patience. And a lot of money.

Here's a rundown of where things stand.

Who's offering spaceflights?

Two companies are offering short "suborbital" hops of a few minutes: Jeff Bezos' Blue Origin and Virgin Galactic, founded by Richard Branson.

Blue Origin's New Shepard rocket takes off vertically and the crew capsule detaches and crosses the Karman line (62 miles, or 100 kilometers, in altitude), before falling back to Earth with three parachutes.

Virgin Galactic uses a massive carrier plane, which takes off from a horizontal runway then drops a rocket-powered spaceplane. This in turn soars to over 50 miles altitude before gliding back.

In both cases, up to six passengers are able to unbuckle from their seats to experience a few minutes of weightlessness and take in the view of Earth from space.

Jeff Bezos, the richest person in the world, is set to join the astronaut club Tuesday on the first crewed launch by Blue Origin, another key moment in a big month for the fledgling space tourism industry.

The mission comes days after Virgin Galactic founder Richard Branson crossed the final frontier, narrowly besting the Amazon magnate in their battle of the billionaires.

Blue Origin's sights are, however, set higher: both literally in terms of the altitude to which its reusable New Shepard craft will ascend compared to Virgin's spaceplane, but also in its future ambitions.