  Let E be the supersingular elliptic curve defined over k, the algebraic
closure of the finite field with two elements, which is unique up to
k-isomorphism. Denote by 0 its identity element and let C be the quotient of
E-{0} under the action of the group Isom(E) (which is non-abelian, of order
24). The main result of this paper asserts that the set C(k) naturally
parametrizes k-isomorphism classes of Lam\'e covers, which are tamely ramified
covers of the projective line unramified outside three points having a
particular ramification datum. This fact is surprising for two reasons: first
of all, it is the first non-trivial example of a family of covers of the
projective line unramified outside three points which is parametrized by the
geometric points of a curve. Moreover, when considered in arbitrary
characteristic, the explicit construction of Lam\'e covers is quite involved
and their arithmetic properties still remain misterious. The simplicity of the
problem in characteristic 2 has many deep consequences when combined with
lifting techniques from positive characteristic to characteristic 0. As an
illustration, we obtain some sharp statements concerning the (local) Galois
action, as, for example, a bound on the number of isomorphism classes of Lam\'e
covers defined over a fixed number field, only depending on the degree of the
residual extension at 2. Finally, in the appendix we give a partial
generalization of these results by showing that, for any positive integer g,
the k-rational points of a suitable quotient of a genus g hyperelliptic curve
parametrize k-isomorphism classes of tamely ramified covers of the projective
line unramified outside three points.
