Editing Interplanetary spaceflight (section)

===Aerobraking===
[[File:Apollo cm.jpg|thumb|Artist's rendition of an [[Apollo Command Module]] aerobraking ]]
[[Aerobraking]] uses the [[Celestial body atmosphere|atmosphere]] of the target planet to slow down. It was first used on the [[Apollo program]] where the returning spacecraft did not enter Earth orbit but instead used a S-shaped vertical descent profile (starting with an initially steep descent, followed by a leveling out, followed by a slight climb, followed by a return to a positive rate of descent continuing to splash-down in the ocean) through Earth's atmosphere to reduce its speed until the parachute system could be deployed enabling a safe landing. Aerobraking does not require a thick atmosphere – for example most Mars landers use the technique, and [[Mars#Atmosphere|Mars' atmosphere]] is only about 1% as thick as Earth's.

Aerobraking converts the spacecraft's [[kinetic energy]] into heat, so it requires a [[heatshield]] to prevent the craft from burning up. As a result, aerobraking is only helpful in cases where the fuel needed to transport the heatshield to the planet is less than the fuel that would be required to brake an unshielded craft by firing its engines. This can be addressed by creating heatshields from material available near the target.<ref>{{Cite web |url=https://www.nasa.gov/pdf/744615main_2011-Hogue-Final-Report.pdf |title=NASA.gov |access-date=2016-05-13 |archive-date=2016-06-02 |archive-url=https://web.archive.org/web/20160602012046/https://www.nasa.gov/pdf/744615main_2011-Hogue-Final-Report.pdf |url-status=dead }}</ref>