Comment by dehef

    Observable.of(rosetta)
         .map(rocket => gravityAssist(rocket,'Earth'))
         .map(rocket => gravityAssist(rocket,'Mars'))
         .map(rocket => gravityAssist(rocket,'Earth'))
         .map(rocket => gravityAssist(rocket,'Earth'))
         .do(rocket => land(rocket))
         .do(rocket => tweetVideo())
         .catch(error => kaput(error))