An observation satellite is used for obtaining information about electromagnetic energy emitted from the earth. The observation satellite orbits the earth in an orbit having an inclination larger than 90° and smaller than 270°. Further, the observation satellite comprises at least one receiving antenna, the at least one receiving antenna having a receiving pattern directed towards the earth, and suitable for receiving electromagnetic energy in the radio frequency range as the observation satellite is orbiting relative to the surface of the earth. The observation satellite also comprises a transmitter configured for at least one of: (i) retransmitting, to a relay spacecraft, the received electromagnetic energy, (ii) transmitting, to the relay spacecraft, information representing the received electromagnetic energy, and (iii) transmitting, to the relay spacecraft, information derived from the received electromagnetic energy. The invention also relates to systems and methods therefor.