Abstract: An ascent vent cover (24) for covering and sealing vent holes (22) in a payload launch vehicle (21) is disclosed. The ascent vent cover (24) includes a magnetic sheet (32) for covering the vent hole (22) and attaching the ascent vent cover to the payload launch vehicle, a plurality of magnets (34a, 34b, 34c, . . . ) for augmenting the holding strength of the magnetic sheet, and a stiffening panel (38) for facilitating the peeling of the ascent vent cover away from the payload launch vehicle (21). The magnets (34a, 34b, 34c, . . . ) are secured to the magnetic sheet (32) so that some are positioned in a circular pattern so as to surround the underlying vent hole (22) and others are positioned along a leading edge of the magnetic sheet (32). The stiffening panel (38) includes a cover portion (39) and a tab portion (40) for securing to the magnetic sheet (32). The magnets (34a, 34b, 34c, . . . ) are embedded in the cover and tab portions.