The boundary of a lunar base is a square \(1 \mathrm{~km}\) wide and \(1 \mathrm{~km}\) long in the Moon reference frame. Spaceship A flies at high relative speed close to the Moon parallel to the edge that we shall call the length of the field. Crew A measures the length and width, and reports that the area of the field is \(0.5 \mathrm{~km}^{2}\) in reference frame A. Spaceship B flies with the same relative speed as spaceship A, but parallel to one diagonal of the field. Crew B measures both diagonals. What surface area does crew B calculate in reference frame \(B\) ?