the asteroid ’ s mass and delta V . Other factors , like the asteroid ’ s spin and whether or not it is travelling in an asteroid pair , also factor into the difficulty of re-directing the asteroid to a location for harvesting .
Thus , any given asteroid ’ s trajectory , mass , spin and more must be taken into account when planning a retrieval operation . Additionally , any missions must also be timed to take advantage of periods when the asteroid is already moving closer to the Earth .
How close are we ?
In order to understand how much additional research and effort may be required to make harvesting asteroids a reality , we should take a look at the history of human efforts to retrieve materials from space for scientific study .
By far the largest amounts of samples ever recovered from outer space were achieved during the race to the moon between the USA and USSR during the 60s and 70s . NASA retrieved a total of 382 kg of material from the Apollo missions between 1969 and 1972 .
Automated ‘ Luna ’ spacecraft sent by the USSR also brought back about 300 g worth of samples . It took another 30 years before any other serious efforts to retrieve material from space were attempted .
NASA ’ s Stardust spacecraft passed near comet Wild-2 in 2004 and used an aerogel-based sample collector to capture dust from the comet . Due to its extremely high porosity , the aerogel made ideal material for slowing down and trapping the very high-velocity dust particles without destroying them .
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