A large aperture particle detector integrated with an electromagnetic antenna. By combining functions of spacecraft subsystems into a single integrated system, a larger particle collector is achieved to provide greater particle measuring sensitivity and costs are reduced through consolidation of functions. The integrated subsystems include a conventional high-gain spacecraft dish antenna and a large aperture particle collector. The conventional high-gain spacecraft dish antenna reflects and focuses impinging electromagnetic radiation at an electromagnetic detector and source, and may comprise one or more reflecting and focusing surfaces. The antenna is used to transmit and receive electromagnetic radiation. The large aperture particle collector is collocated with the electromagnetic antenna. The large aperture particle collector reflects and focuses impinging charged particles at a particle detector through the use of one or more electrostatic mirrors. The electrical potential applied to the electrostatic mirrors may be adjusted to select particles having a specific range of particle energies to be reflected and focused on the particle detector.