Phan Dao, AFRL; Kristen Haynes, Applied Optimization Inc.; Victoria Frey, Applied Optimization; Cory Hufford, Applied Optimization; Kyle Schindler, Applied Optimization; Tamara Payne, Applied Optimization Inc.; Jeff Hollon, Applied Optimization
Keywords: cislunar, simulation, photometry, Space Domain Awareness (SDA), General Mission Analysis Tool (GMAT), Satellite Visualization and Signature Tool (SVST)
Abstract:
Lately, there has been an increased global interest in sending satellites to the Moon. As more objects enter the cislunar domain, cislunar Space Domain Awareness (SDA) is becoming a necessity. Since most SDA is currently concerned with objects from Low Earth Orbit (LEO) to Geosynchronous Earth Orbit (GEO), much work has already been done to study the photometry of objects in these orbits. Some of this knowledge can be applied to the study of cislunar objects.
Like objects in GEO, imagery of cislunar objects will be unresolved from ground-based sensors or space-based sensors due to the distances involved. Additionally, objects orbiting the Moon or the L1 or L2 Lagrange points will repeat a pattern of photometric behavior once per lunar cycle, which can be used to predict future behavior. However, unlike GEO objects, which repeat a pattern of photometric behavior over the diurnal cycle, there is a wider variety of cislunar orbital shapes causing a wider variety of photometric behavior. Also, cislunar space is a much larger volume of space so tracking and predicting the behavior of cislunar targets is a more complicated problem.
Simulating photometry for a variety of cislunar scenarios will be useful to help predict behavior of future objects flown in cislunar space. We have simulated various cislunar scenarios using NASAs General Mission Analysis Tool (GMAT). Photometry for these orbits were then simulated using the Satellite Visualization and Signature Tool (SVST) for targets of differing sizes. The sensor for these simulations was placed either on Earth or on the Moon to get a perspective of how the photometry and observability of the target changes with the sensor location.
With these simulations, we are able to analyze the photometry of an object in all stages of a cislunar orbit (i.e., Earth orbit, transfer, lunar/L1/L2 orbit). We are also able to specify expected signal strength for typical spacecraft and interference noise based on the geometry of the sensor, target, the Moon, and the Sun. This paper will describe the different orbits studied, present the simulation results with special attention to cislunar object brightness ranges, photometric signature patterns, and observability.
Date of Conference: September 15-18, 2020
Track: Cislunar SSA