How to Drop an Egg From Space Without Breaking It

TL;DR

An egg's terminal velocity is about 75 miles per hour, so a mattress can safely catch one dropped from any height. To attempt the world's highest egg drop, the plan clamps an egg to a fin-guided rocket carried up by a weather balloon, letting gravity accelerate it past Mach One before it steers itself down and releases the egg 300 feet above a target mattress.

Transcript

• This is space, and this is an egg moments before I attempted the world's highest egg drop. Now in an egg drop competition, in case you never had the chance to do it yourself in school, the goal is to build a contraption that can protect a raw egg from breaking when dropped from the tallest height possible. So my original plan was to drop an egg i... Read More

Key Insights

• Terminal velocity is the maximum speed a falling object reaches once Earth's gravitational pull balances the increasing air resistance from hitting more air molecules; for humans it is about 120 miles per hour and for an egg roughly 75 miles per hour.
• The core plan attaches an egg to the front of a rocket carried by a weather balloon to space, where gravity alone accelerates it past Mach One before four movable tail fins autonomously steer it to release the egg 300 feet above a mattress.
• A mattress can protect an egg dropped even faster than its terminal velocity; an early test recorded 83 and the egg showed no cracks, proving the landing surface concept before spending money on the full space attempt.
• The payload system needed a small heated oven to keep the egg from freezing on the way up, a mechanism to break that oven away before the drop, and a separate mechanism to release the egg itself.
• A metallic tracking streamer added to the rocket's back interfered with the GPS signal, corrupting the rocket's speed calculations so it wrongly thought it was time to release the egg; swapping to a plastic streamer fixed it.
• Weather balloons steer their landing by exploiting known wind direction and speed at every altitude; launching from the right spot on a given day puts the balloon directly above a target when it reaches a chosen height like 10,000 feet.
• Global weather prediction relies on about 2000 weather balloons launched daily from over a thousand locations at noon and midnight London time, each carrying a radiosonde that transmits altitude, pressure, temperature, and wind data to supercomputers.
• A single rogue negative sign in the flight control code caused the rocket's fins to force it into an uncontrolled death spiral during one test, showing how one character can undo years of engineering analysis and testing.

Questions & Answers

Q: What is terminal velocity and how fast does an egg fall?

Terminal velocity is the maximum speed an object reaches while falling, occurring when Earth's gravitational pull toward the ground balances the pushback force from bumping into more and more air molecules as the object speeds up. For humans this maximum speed is about 120 miles per hour. After doing some simple math for an egg, it tops out at 75 miles per hour, meaning an egg cannot fall faster than that no matter the drop height.

Q: How was the egg supposed to survive the drop from space?

The plan clamps an egg to the front of a rocket, which is attached to a weather balloon and taken up to space. Once there, the balloon releases it and, using gravity only, the rocket accelerates past Mach One, breaking the speed of sound. It then autonomously adjusts four fins on the back to steer toward the target, and at 300 feet above the ground releases the egg to free fall onto a mattress placed on the ground.

Q: Why does a mattress protect an egg at high falling speed?

Because an egg's terminal velocity is only about 75 miles per hour, a mattress can absorb the impact and cushion it enough to prevent breaking. The team tested this directly, dropping an egg onto a mattress and recording a reading of 83, which is faster than the egg's terminal velocity, and the egg showed no cracks. This proved the landing surface could protect the egg even when traveling faster than it ever would in free fall.

Q: Who is Joe from BPS Space and what was his role?

Joe runs a channel called BPS Space and, notably, never went to school for any kind of engineering degree; he is entirely self-taught. He recently landed a launched rocket SpaceX style after seven years of trying. In this project, Joe was in charge of tracking and guiding the rocket to the mattress using the movable tail fins, handling the steering and control side while Mark focused on the egg payload.

Q: Why did the first launch attempt get scrubbed?

The team had a GPS failure right before launch, and the egg was released prematurely, being ejected from the rocket while they were walking back. Later testing confirmed that the last-minute addition of a metallic tracking streamer at the back of the rocket, near the GPS unit, was interfering with the GPS signal. That interference corrupted the rocket's math in calculating its speed, so it wrongly concluded it was time to release the egg. They fixed this by swapping the metallic streamer for a plastic one.

Q: How do weather balloons know where they will land?

Computers know the wind direction and speed at every height as a balloon rises. On a given day, using the predicted wind directions and speeds at each altitude, engineers can calculate the exact spot to launch so the balloon is directly above the target when it reaches a chosen height, such as 10,000 feet. By choosing the launch point based on these layered wind predictions, the balloon effectively steers itself to the intended landing zone.

Q: How are accurate wind and weather predictions actually made?

Every day it is someone's job to launch two balloons into the sky at noon and midnight London time, and this happens in over a thousand locations around the world at those same two exact moments. Each balloon carries a device called a radiosonde that measures altitude, pressure, temperature, and wind, then transmits the information back to ground stations that feed it into supercomputers. About 2000 of these massive weather balloons go up every day, which is why predictions can be so accurate.

Q: What went wrong during the low-altitude test flights?

The tests at 10,000 feet faced several problems. On one attempt the balloon rose slower than anticipated, throwing off the predicted trajectory and drifting too far south, forcing a manual rocket drop. The fins then forced the rocket into an uncontrolled death spiral, and it crashed from an altitude around 1400 while coming down fast, though the egg did release. Joe later reviewed the footage and firmware and found a single rogue negative sign in the code that was causing all the control issues.

Summary & Key Takeaways

• The goal is the world's highest egg drop, protecting a raw egg dropped from the tallest possible height. Rather than use the tallest building, the plan goes to space: an egg is clamped to a rocket carried up by a weather balloon, then falls back and steers itself to a mattress.

• The team calculates an egg's terminal velocity at about 75 miles per hour and confirms a mattress can catch it safely, recording 83 with no cracks. Work happens in Gridley, California, with self-taught BPS Space rocketeer Joe handling fin-guided steering while Mark manages the heated egg payload.

• Low-altitude 10,000-foot tests hit repeated problems: a metallic streamer disrupts the GPS forcing a scrub, a slow-rising balloon throws off trajectory, and a code error spins a rocket into a crash. After fixing a rogue negative sign, the final attempt lands much closer, near 98 meters altitude.