Elon Musk took to Twitter to make an announcement about a new method that SpaceX will use to save the upper stage of its Falcon 9 rocket. Musk announced that the company is considering the use of a giant party balloon.
This isn't the first time that Musk has made an outrageous claim that later turned out to be true.
Giant Party Balloon
Musk tweeted about the use of a giant party balloon on April 15. This is the first time that Musk or SpaceX has acknowledged that they may try to save the second stage of a rocket. SpaceX is known for having pioneered the retrieving and reusing of the first stage of its rockets.
Reusing parts of rockets has reduced the cost of sending the rockets into space. SpaceX does this by having the first stage reignite its engines to stabilize its descent--this lets it slow down enough so that it can land upright. The second stage of the rocket has been more difficult to capture.
The second stage travels much faster than the first stage. Falcon 9's first stage travels up to 5,000 miles per hour before it returns to Earth. The second stage has to reach low Earth orbit so it travels at a speed of up to 17,000 miles per hour. This means that it will come back down to Earth much faster and at hotter temperatures than the first stage.
Falcon 9's second stage is 27 times hotter than the first stage when it makes its descent. This temperature causes portions of the rocket to melt and causes it to break apart. Musk wants to slow down the rocket so that it won't reach the blistering temperatures and break apart.
Reducing Heat
To prevent the second stage from melting, this would require the second stage to deploy a heat shield to prevent it from melting and breaking apart. It would be possible for SpaceX to deploy an inflatable balloon at the bottom of the second stage to reduce the concentration of the heat by expanding the surface area.
This balloon would also be able to slow down the second stage. Increasing its shape would allow greater air resistance when it's coming down back to Earth. It makes it easier for the object to be caught up in the air.
This isn't the first time that SpaceX has used an outlandish idea to be able to retreat part of the rocket. Previously, SpaceX was using a boat named Mr. Steven to retrieve the fairing from the rocket. The last time that it tried to estimate where the fairing would fall, the measurements were just only a few hundred yards off from being able to catch it.
