gold. M-type asteroids are rare but contain up to 10 times more metal than S-types. A class of easily retrievable objects (EROs) was identified by a group of researchers in 2013. Twelve asteroids made up the initially identified group, all of which could be potentially mined with present-day rocket technology. Of 9,000 asteroids searched in the NEO database, these twelve could all be brought into an Earth-accessible orbit by changing their velocity by less than . The dozen asteroids range in size from . Asteroid cataloging The B612 Foundation is a private nonprofit foundation with headquarters in the United States, dedicated to protecting Earth from asteroid strikes. As a non-governmental organization it has conducted two lines of related research to help detect asteroids that could one day strike Earth, and find the technological means to divert their path to avoid such collisions. The foundation's 2013 goal was to design and build a privately financed asteroid-finding space telescope, Sentinel, hoping in 2013 to launch it in 2017–2018. The Sentinel's infrared telescope, once parked in an orbit similar to that of Venus, is designed to help identify threatening asteroids by cataloging 90% of those with diameters larger than , as well as surveying smaller Solar System objects. After NASA terminated their $30 million funding agreement with the B612 Foundation in October 2015 and the private fundraising did not achieve its goals, the Foundation eventually opted for an alternative approach using a constellation of much smaller spacecraft which is under study . NASA/JPL's NEOCam has been proposed instead. Mining considerations There are four options for mining: In-space manufacturing (ISM), which may be enabled by biomining. Bring raw asteroidal material to Earth for use. Process it on-site to bring back only processed materials, and perhaps produce propellant for the return trip. Transport the asteroid to a safe orbit around the Moon or Earth or to the ISS. This can hypothetically allow for most materials to be used and not wasted. Processing in situ for the purpose of extracting high-value minerals will reduce the energy requirements for transporting the materials, although the processing facilities must first be transported to the mining site. In situ mining will involve drilling boreholes and injecting hot fluid/gas and allow the useful material to react or melt with the solvent and extract the solute. Due to the weak gravitational fields of asteroids, any activities, like drilling, will cause large disturbances