System design of a miniaturized distributed occulter/telescope for direct imaging of star vicinity

The Space Rendezvous Laboratory (SLAB) at Stanford is investigating the feasibility of a miniaturized distributed occulter/telescope system (mDOT) to directly image exozodiacal dust and Jovian exoplanets. The mDOT mission relies on formation flying in Earth orbit and promises a drastic decrease of the expected mission cost compared to large scale missions, such as NWO and Exo-S (NASA). The preliminary system design of mDOT, described in this paper, is complemented by concurrent novel studies of optimal formation dynamics and diffractive optics design. mDOT consists of a microsatellite carrying a 1 meter radius petal shaped occulter at a distance of 500 km from a 6U CubeSat carrying a 10 cm diameter aperture telescope designed to image at short visible and ultraviolet wavelengths. Following a systems analysis, based on the definition of mission requirements and a survey of CubeSat capabilities, the telescope spacecraft provides 80 days of operation with 50 W solar cells, 31 m/s of delta-v capability using cold gas thrusters. Together with ad-hoc relative metrology instruments, these are used for lateral alignment with the occulter spacecraft at 15 cm position control accuracy. The goal of the mDOT mission is to prove that a space telescope with an external star occulter can be miniaturized, greatly reducing the mission cost and complexity. As shown in this paper, the proposed mission has the capability to directly image the vicinity of nearby stars and, at the same time, prove that miniaturized space systems are capable of executing complex missions. mDOT can serve as a first-of-a-kind precursor, paving the way for larger missions with higher scientific return.