"It's a crazy endeavour," Professor Bong Wie, founding director of the Asteroid Deflection Research Centre at Iowa State University, told me over the phone. "This kind of initiative should have been done by government agencies, not the people. [Governments], however, aren't taking this threat seriously."
Wie is one of the people behind the "Help Defend Earth Against Asteroid Threats" Indiegogo campaign, which was launched by international NGO Emergency Asteroid Defence Project (EADP) yesterday and is looking to raise $200,000. It aims to protect Earth from rogue asteroids by building a "hypervelocity asteroid intercept vehicle" (HAIV). This is a small spacecraft that promises to "deflect or disperse asteroids and comets" at short notice.
The project page explains that "no definitive solution" to the asteroid threat has been found by scientists or government agencies to date. It cites the US Congress asking NASA to come up with an anti-asteroid strategy in 2005, a program that was deemed lacking in 2014 due to a shortage of funding and resources.