How Do Spacecraft Slow Down

How do spacecraft slow down? Rigid heat shields and retro propulsion have been the favorites of engineers for years. Now NASA is testing a new inflatable heat shield technology that could allow us to carry even larger payloads to worlds with atmospheres:
https://www.nasa.gov/loftid

Launching on Nov. 1 aboard a United Launch Alliance Atlas V rocket along with NOAA’s JPSS-2 mission, the Low-Earth Orbit Flight Test of an Inflatable Decelerator, or LOFTID, will demonstrate the heat shield’s ability to slow down.