Complex sentence: Peter Langkjær Madsen (born 12 January 1971) is a Danish engineer and entrepreneur, co-founder of the non-profit organization Copenhagen Suborbitals (which he left in 2014), and founder and CEO of RML Spacelab ApS.
Split into simpler sentences: Peter Langkjær Madsen (born 12 January 1971) is a Danish engineer and entrepreneur. He co-founded the non-profit organization Copenhagen Suborbitals but left it in 2014, becoming the founder and CEO of RML Spacelab ApS.