The 1-m STARS telescope was one of the five candidates for the coming ESA medium size (M3) mission. Based on the very compact Triply Reflecting Telescope concept, the STARS telescope provides diffraction limited image performance over a large field of view (+/- 0.75 degree(s)). Two different focal plane instruments, the Astero Seismology Detector and the Activity Line Monitor observe simultaneously in different wavelength bands in the range from 110 to 750 nm. Within the frame of an ESTEC conducted phase A study, the optical, mechanical, and thermal design of the complete telescope assembly including the accommodation on the service module has been investigated. A stiff and lightweight hexapod trusswork structure with struts from carbon fiber reinforced composites has been worked out as the most advantageous concept with respect to mass, opto- mechanical, and thermal properties. The major issues were the maintenance of an axial distance stability of +/- 10 micrometers between primary and secondary mirror as well as the fulfillment of certain thermal requirements for the two scientific instruments (Activity Line Monitor and Asteroseismology Detector). The finally chosen concept has a fully reflective optical design with higher order aspheric optical surfaces, a passive thermal design, is extremely lightweight (< 190 kg), and has a high stiffness (all eigenfrequencies are above 60 Hz). For the optics, a simpler approach with only conical reflective surfaces and an additional refractive correction element has been investigated.