The transient emission of astrophysical sources can shed some light onto the most extreme conditions matter can be exposed to in the universe, which are not reproducible on Earth. Current established technologies, such as small-field-of-view grazing-incidence optics and Charged Coupled Devices, are inadequate in this context, as they do not ensure the required grasp, sensitivity and throughput necessary to observe bright transients, and to discover and monitor known or new sources. In this paper, I will be reviewing some new technologies and proposed mission concepts for the study of astrophysical X-ray transients from space, both on board satellites and from the surface of the Moon. All presented instruments are based on the sensor technology of Silicon Drift Detectors coupled with new-generation optical systems, with the goal of solving current technological limitations.