This study attempts to answer the question of what space is made of and explores in this objective the analogy between the Einstein’s gravitational geometrical theory in one- and two-dimensional linear deformations and a possible space material based on strain measures done on the Ligo or Virgo interferometers. It draws an analogy between the Einstein’s gravitational constant $\kappa$ and the Young’s modulus and Poisson’s ratio of an elastic material that can constitute the space fabric, in the context of propagation of weak gravitational waves. In this paper, the space is proposed to have an elastic microstructure of $1.566\times10^{-35}$ m grain size as proposed in string theory, with an associated characteristic frequency $f$. The gravitational constant $G$ is the macroscopic manifestation of the said frequency via the formula $G = \pi f^ 2/\rho$, where $\rho$ is the density of the space material.