How can I contribute to Spark?
Yes, Spark is an open source project and anyone can contribute to it.
The Spark team is always looking for new contributors to join the team.  You can start by

How can I get involved with Spark?
How can I get a job at Spark?

<separator><separator><separator><separator><separator><separator> Scala, Scala, Scala, Scala, Scala, Scala, Scala,