Insert the white end of one SCIENCE INSTRUMENT BOOM through hole A the SOLAR PANEL. Push it in until it just enters hole A in the SPACECRAFT BUS. The white part will end up about at the end of the rectangle marked A. Apply glue sparingly at all points of contact, and arrange so that the boom sticks straight out (perpendicular to the tangent of the solar panels). If necessary, bend rectangle A up slightly to support the boom straight out. Prop it until the glue dries thoroughly.
Repeat the above step with the two remaining SCIENCE INSTRUMENT BOOMS. Make sure they are straight as the glue dries.