from Hacker News

SpaceX successfully launches and lands a used rocket for the second time

by tsaprailis on 6/23/17, 8:42 PM with 3 comments

• by blastofpast on 6/23/17, 8:48 PM

  Musk tweeted that the rocket booster used "almost all of the emergency crush core" which, according to the article, "helps soften the landing".

  Can someone explain what this means? What is an emergency crush core?