We present the concept of using an orbiting laser as a coherent optical reference to phase a several kilometer diameter array of ground-based lasers designed to accelerate interstellar nano-spacecraft to 20% light-speed using laser propulsion. We investigate the geometrical and temporal constraints for the initial case of the target star Proxima b in the Alpha Centauri system using a laser ground site in the southern hemisphere. Based on these constraints, we detail requirements for the mission architecture for an orbiting laser to be used as an optical reference. We then present two orbits that can meet all given requirements and represent a range of engagement times and days between engagements. We also present a range of orbits with periods from 3 to 4 days and engagement times from 660 to 800 s. If desired, the orbit can be matched to the sidereal day, so each orbit period, the beacon can align with the ground station and the same target star without maneuvers. A discussion of the tradeoff between the Earth-based site latitude, time on engagement, and days between engagements is presented.
Ground-based observatories’ capabilities can be greatly enhanced by working with satellites in astrostationary orbits. Satellites inertially aligned with ground-based observatories can help mitigate atmospheric effects in astronomical, solar, and planetary observations. We present a method for developing and modeling the trajectory of potential astrostationary orbits as seen from the ground to understand whether they meet defined astrostationary conditions such as the location in the field of interest and the observation time. It discovers an L2 orbit family and shows that it can meet astrostationary conditions. It then presents an example mission, Orbiting Configurable Artificial Star (ORCAS), in which a satellite aligns with a ground-based observatory to provide near-diffraction limited observations in the visible wavelength. A highly elliptical orbit family which can meet the ORCAS requirements is studied, and we go on to show how multiple observations can be made during a single-orbit period and how specific configurations that increase the observation time can be found. Finally, other potential astrostationary families are presented, as well as additional applications that could benefit from spacecraft and ground-based observatories working together, and future work which can be done to move forward in the field is discussed.
We establish a viable laser payload design for the Orbiting Configurable Artificial Star (ORCAS) mission. We share observational considerations and derive the engineering requirements for the laser payload. Developed by general Atomics Electromagnetic Systems, the dual-wavelength laser will operate at 1064 nm and can be frequency-doubled to 532 nm, with two possible beam divergence modes and tunable power. The laser payload can be operated at pulse repetition rates greater than 10 kHz to enable compatibility with Adaptive Optics systems and to maintain pointing requirements. We show that such a laser payload can be constructed based upon a high-TRL amplified fiber laser Communication Terminal modified to meet the mission requirements.
In this paper, we establish the mission operation concept for the Orbiting Configurable Artificial Star mission, a hybrid space-ground observatory, which aims to enable ground observations of near-diffraction limited resolution and exquisite sensitivity. We present the mission requirements, introduce a potential orbit solution that can meet them, detail the concrete operational steps to be taken to enable such observations, and develop a mission planning tool which generates a mission schedule that meets all mission requirements and can be altered in real time in the case of disruptions to the mission. Finally, we show the the mission could enable 300 adaptive optics and 1500 flux calibration observations throughout its lifetime.
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