A spacecraft includes: an antenna unit 20 including a first layer film 11 and a second layer film 14, the first layer film 11 including a plurality of slit-like openings 13 in a film that does not allow transmission of an electromagnetic wave 16, and the second layer film 14 including a light receiving element 15 that detects a coherent electromagnetic wave transmitting through the plurality of openings; and a processing unit 21 configured to estimate an arrival direction of the electromagnetic wave from signal intensities of the electromagnetic waves detected by the light receiving element.

A satellite for operation in orbit around the earth comprises an ADCS configured for mechanically steering the satellite in the azimuth direction to prolong a dwell time, during which a selected target is visible from the satellite, as the satellite orbits over the target. A processor at the ground station may be configured to process raw SAR data from any of the satellites described here. The raw SAR data may be processed in a number of ways to provide image information including but not limited to forming multilook images, compiling video sequences and colour coding images.

A satellite system operates at altitudes between 180 km and 350 km relying on vehicles including an engine to counteract atmospheric drag to maintain near-constant orbit dynamics. The system operates at altitudes that are substantially lower than traditional satellites, reducing size, weight and cost of the vehicles and their constituent subsystems such as optical imagers, radars, and radio links. The system can include a large number of lower cost, mass, and altitude vehicles, enabling revisit times substantially shorter than previous satellite systems. The vehicles spend their orbit at low altitude, high atmospheric density conditions that have heretofore been virtually impossible to consider for stable orbits. Short revisit times at low altitudes enable near-real time imaging at high resolution and low cost. At such altitudes, the system has no impact on space junk issues of traditional LEO orbits, and is self-cleaning in that space junk or disabled craft will de-orbit.

The system is configured to generate a display of a tagging interface. The tagging interface may include a stitching selector. In response to a user selection of (1) a destination element that includes a first name identifier, (2) a source element that includes at least one of the plurality of pixels such that at least one of the plurality of pixels corresponding to longitude-time points comprising a second name identifier, and (3) the stitching selector, the system can be configured to indicate that the source element comprises the first name identifier.

An Earth monitoring system comprises a satellite constellation (310) and a schedule calculation module (302) located on Earth. The schedule calculation module (302) may be configured to implement a satellite management method receiving a request post-launch for a location to be imaged; recalculating an existing schedule of the satellites to provide an updated schedule that includes imaging the location; and providing the updated schedule for transmission to one or more of the satellites.