An asteroid is moving directly towards the centre of the earth. When at a distance of $10R$ ($R$ is the radius of the earth) from the centre of the earth, it has a speed of $12 \mathrm{km} {\mathrm{s}}^{-1}.$ Neglecting the effect of earth's atmosphere, what will be the speed of the asteroid when it hits the surface of the earth (escape velocity from the earth is $11.2 \mathrm{k}\mathrm{m} {\mathrm{s}}^{-1})$ ? Give your answer to the nearest integer in $\mathrm{km} {\mathrm{s}}^{-1}$__________.