Space startup Rocket Lab is taking on Elon Musk's SpaceX with a huge new reusable rocket called Neutron that could be used to transport humans to space. The California and New Zealand based firm has merged with a special-purpose acquisition company to go public, valuing the joint venture at $4.1 billion. Rocket Lab will use its new position and a $740 million cash balance to develop the new 8-Ton Neutron rocket that can launch mega-constellations of satellites. The Neutron rocket will be 40 metres tall, have a reusable first stage and capable of taking up to 8,000 kg of material to orbit on each flight.