The Red Bull Stratos team and Felix Baumgartner are gearing up for another try at breaking the record for highest ever freefall and breaking the sonic barrier carried by nothing but gravity.
While "falling down" sound simple enough there's a lot of technology involved in the jump from the complex camera setup
created to film the jump, to the next-generation full-pressure suit, more advanced than the ones astronauts wear, to the balloon that will carry Felix Baumgartner to 23 miles, 36.5 km.
The balloon is the largest ever built to carry humans and is truly gigantic. It's made up of a very thin sheet of polyethylene, 0.0008 inches, 0.02 mm thick.
Even so, the balloon, without the capsule it's lifting, weights 3,708 lbs or 1,682 kg and that's because it's huge.
Stretched out, it would cover 40 acres, 161,874 square meters. It's 180 m or 592 feet long before being inflated and will stand 167 m or 550 feet tall at launch.
The balloon will be tall and thin at launch, but the drop in pressure as it rises means it will be almost completely spherical once it reaches its maximum height.
It will also double in height, to 335 feet or 102 m with a diameter of 424 feet or 129 meters.
It needs to be this large to accommodate the expanding helium as the balloon rises. At ground level, the balloon will be filled with 5,097 cubic meters or 180,000 cubic feet of helium.
36.5 km into the atmosphere though, it will expand to almost 850,000 cubic meters or 30 million cubic feet.
It will be 10 times larger than the balloon that carried Joe Kittinger, the current record holder for highest jump, back in 1960 and three times larger than the biggest helium balloon to carry humans.
The team had two of these balloons for the jump and they've wasted one already during this week's attempt