• how do they slow down for re-entry

Reusable rockets employ several key techniques to slow down and land safely after launch:

1. Flip maneuver: After stage separation, the rocket flips around using cold gas thrusters near its nose to orient itself for descent.
2. Boostback burn: The rocket reignites some of its engines to slow its horizontal velocity and begin moving back towards the landing site.
3. Reentry burn: As the rocket reenters the atmosphere, it fires its engines again to slow down from hypersonic speeds and protect itself from intense heating.
4. Grid fins: Heat-resistant fins deploy to help steer and stabilize the rocket during descent.
5. Landing burn: Just before touchdown, the engines fire one final time to slow the rocket to landing speed.
6. Throttleable engines: The ability to precisely control engine thrust is crucial for controlled descent and landing.
7. Onboard computer: Advanced software constantly calculates and adjusts the rocket's trajectory using sensor data.
8. Landing legs: Deployable legs absorb the impact of landing.

These systems work together to slow the rocket from speeds of around 4,700 km/h to just 20 km/h for landing

. The process requires precise timing and control to manage fuel consumption and successfully touch down on a relatively small landing pad or ship.

The rocket doesn't use traditional mechanical brakes like those found on aircraft. Instead, it relies on precisely controlling its engine thrust to manage its descent and landing speed. This approach allows for a controlled, soft landing that protects the rocket's engines and structure from damage, making rapid reuse possible

.The use of propulsive landing also avoids the need for additional heavy mechanical systems, which would reduce the rocket's payload capacity. By using the existing engines for landing, SpaceX maximizes efficiency and reusability.

• would be a hard implementation considering there aren’t moving parts involved in propulsion like trains

• see how aeroflux was thinking about the integration into planes and why brake +propellant works for planes but less so for spacecrafts

  • The key to my design is a patent pending electromagnetic array that creates a very specific magnetic field distribution across the discs. The magnetic field is distributed in just the right way so as to concentrate magnetic flux in areas of the disc that result in the greatest constructive interference between circulating eddy currents. This results in a much higher eddy current density in the disc and therefore a larger braking torque. This technology means that my design uses almost no power, weighs only slightly more, and fits within the exact same envelope as a conventional aircraft brake.
  • multi-directional electromagnetic array creates a very specific magnetic field distribution across the disc

  Existing types of em arrays