"The lander is a strong,
lightweight structure, consisting of a base and three sides "petals"
in the shape of a tetrahedron (pyramid-shaped). The Lander structure
consists of beams and sheets that are made from a "composite"
material. Composites such as fiberglass are made of strong fibers or
fabrics that are stiffened with a glue, or "matrix". The lander
beams are made out of carbon-based layers of graphite fiber woven
into a fabric, creating a material that is lighter than aluminum and
more rigid than steel."