Its density was found to be very low ( around 1.2 times the density of water ) , indicating that the asteroid has a lot of empty spaces ; From 25 % to as much as 60 % of it may be empty space , depending on the details of what it 's made of . Its density was found to be very low ( around 1.2 times the density of water ) , indicating that the asteroid is porous to very porous ; from 25 % to as much as 60 % of it may be empty space , depending on the details of its composition .